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1
Harland, R., Anne P. Bonny, M. J. Hughes, and A. N. Morigi. "The Lower Pleistocene stratigraphy of the Ormesby Borehole, Norfolk, England." Geological Magazine 128, no. 6 (1991): 647–60. http://dx.doi.org/10.1017/s0016756800019749.
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AbstractThe sedimentology, micropalaepntology and palynology of Lower Pleistocene sediments recovered from a borehole at Ormesby St Margaret, near Great Yarmouth, Norfolk, have been investigated. The sediments, consisting of a lower clay facies overlain by an upper predominantly sandy facies, were deposited in inner neritic environments. Micropalaeontological and palynologicalevidence allows comparisons with the nearby Ludham sequence but an unequivocal correlation cannot be made. The Ormesby Borehole sequence includes representatives of the Pre-Ludhamian to Early Pastonian stage interval and the presence of a late Pre-Ludhamian to late Baventian/Pre-Pastonian a hiatus. Foraminiferal faunas matched to grain size analysis are indicative of transportation and considerable post-mortem sorting.
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Weston, Janice F., R. Andrew MacRae, Piero Ascoli, et al. "A revised biostratigraphic and well-log sequence-stratigraphic framework for the Scotian Margin, offshore eastern Canada 1This article is one of a series of papers published in this CJES Special Issue on the theme of Mesozoic–Cenozoic geology of the Scotian Basin. 2Earth Sciences Sector Contribution 20120137." Canadian Journal of Earth Sciences 49, no. 12 (2012): 1417–62. http://dx.doi.org/10.1139/e2012-070.
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In this study, we build on a foundation of previous biostratigraphic studies for the Scotian Basin, offshore eastern Canada, by conducting new quantitative multidisciplinary biostratigraphic studies of the Mesozoic sections in eight wells: Bonnet P-23, Chebucto K-90, Cohasset L-97, Glenelg J-48, Glooscap C-63, Mohican I-100, South Desbarres O-76, and South Griffin J-13. These wells were chosen to provide good spatial coverage, stratigraphic penetration, and correlation with the seismic grid. We have also evaluated pre-existing biostratigraphic data and undertaken the well-log sequence-stratigraphic interpretation of Upper Triassic to Cenozoic sediments in 16 additional wells using a consistent multidisciplinary event scheme derived from the new wells. Key to the dating of some horizons has been integration of the palynology and micropaleontology (disciplines mostly used previously on the Scotian Margin) with new nannofossil data. Simultaneously we have closely integrated the biostratigraphic results with lithofacies, well-log, and seismic interpretations. Using this integrated approach, we have identified nine regionally mappable sequence-stratigraphic events (unconformities and maximum flooding surfaces, or MFSs): the Intra-Oligocene Unconformity; the Ypresian Unconformity; the Turonian/Cenomanian Unconformity; the Late Albian Unconformity; the Aptian/Barremian Unconformity; the Intra-Hauterivian MFS; the Near-Base Cretaceous Unconformity; the Tithonian MFS; and the Top-Callovian MFS. Additional events of local extent were also recognized in some wells. Our study has led to significant revision of some previous lithostratigraphic picks. The Early Jurassic on the Scotian Margin remains poorly resolved and may be represented by an unconformity on much of the basin periphery.
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Dechesne, Marieke, Ellen D. Currano, Regan E. Dunn, et al. "A new stratigraphic framework and constraints for the position of the Paleocene–Eocene boundary in the rapidly subsiding Hanna Basin, Wyoming." Geosphere 16, no. 2 (2020): 594–618. http://dx.doi.org/10.1130/ges02118.1.
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Abstract The Paleocene–Eocene strata of the rapidly subsiding Hanna Basin give insights in sedimentation patterns and regional paleogeography during the Laramide orogeny and across the climatic event at the Paleocene–Eocene Thermal Maximum (PETM). Abundant coalbeds and carbonaceous shales of the fluvial, paludal, and lacustrine strata of the Hanna Formation offer a different depositional setting than PETM sections described in the nearby Piceance and Bighorn Basins, and the uniquely high sediment accumulation rates give an expanded and near-complete record across this interval. Stratigraphic sections were measured for an ∼1250 m interval spanning the Paleocene–Eocene boundary across the northeastern syncline of the basin, documenting depositional changes between axial fluvial sandstones, basin margin, paludal, floodplain, and lacustrine deposits. Leaf macrofossils, palynology, mollusks, δ13C isotopes of bulk organic matter, and zircon sample locations were integrated within the stratigraphic framework and refined the position of the PETM. As observed in other basins of the same age, an interval of coarse, amalgamated sandstones occurs as a response to the PETM. Although this pulse of relatively coarser sediment appears related to climate change at the PETM, it must be noted that several very similar sandstone bodies occur with the Hanna Formation. These sandstones occur in regular intervals and have an apparent cyclic pattern; however, age control is not sufficient yet to address the origin of the cyclicity. Signs of increased ponding and lake expansion upward in the section appear to be a response to basin isolation by emerging Laramide uplifts.
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Osorio-Granada, E., A. Pardo-Trujillo, S. A. Restrepo-Moreno, et al. "Provenance of Eocene–Oligocene sediments in the San Jacinto Fold Belt: Paleogeographic and geodynamic implications for the northern Andes and the southern Caribbean." Geosphere 16, no. 1 (2019): 210–28. http://dx.doi.org/10.1130/ges02059.1.
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Abstract Mesozoic and Cenozoic strata of the San Jacinto Fold Belt (Colombian Caribbean) provide insights about sedimentary environments and paleogeographic evolution in the transition between the northern Andes and the South Caribbean deformed belt. We report new provenance (conventional sandstone petrography, heavy mineral analysis, and detrital zircon U-Pb geochronology and typology) and micropaleontologic data (palynology, calcareous nannofossils, and foraminifera) in samples collected from the lower Eocene (San Cayetano Formation) and upper Eocene–Oligocene (Toluviejo and Ciénaga de Oro Formations) rocks in boreholes drilled by the Colombian Agencia Nacional de Hidrocarburos as well as from recently exposed Oligocene outcrops from the Ciénaga de Oro Formation. Sandstone petrography shows modal variations, with high feldspar content in the lower Eocene rocks and high quartz content in the Oligocene deposits. This shift in compositional maturity may be due to climatic variations, tectonic activity, and/or changes in source areas. Heavy mineral analyses indicate variations that suggest sources primarily related to felsic igneous and/or low-grade metamorphic and mafic and ultramafic rocks. Zircon U-Pb geochronology displays age populations mainly in the Late Cretaceous, Late Jurassic, Permian–Triassic, and Precambrian (ca. 900–1500 Ma). In addition, zircon typology analyses indicate that the igneous zircons came primarily from monzogranites and granodiorites. Finally, the micropaleontologic and sedimentary data sets indicate that the sediments were deposited in tropical coastal and shallow marine environments. The sediments were transported by short rivers from the crystalline massifs of the Lower Magdalena Valley and the northern Central Cordillera basements, while distal transport of sediments may have occurred along longer rivers, which brought sediments from southern regions located between the Central and Western Cordilleras.
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Casson, Max, Jason Jeremiah, Gérôme Calvès, et al. "Evaluating the segmented post-rift stratigraphic architecture of the Guyanas continental margin." Petroleum Geoscience 27, no. 3 (2021): petgeo2020–099. http://dx.doi.org/10.1144/petgeo2020-099.
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Segmentation of the Guyanas continental margin of South America is inherited from the dual-phase Mesozoic rifting history controlling the first-order post-rift sedimentary architecture. The margin is divided into two segments by a transform marginal plateau (TMP), the Demerara Rise, into the Central and Equatorial Atlantic domains. This paper investigates the heterogeneities in the post-rift sedimentary systems at a mega-regional scale (>1000 km). Re-sampling seven key exploration wells and scientific boreholes provides new data (189 analysed samples) that have been used to build a high-resolution stratigraphic framework using multiple biostratigraphic techniques integrated with organic geochemistry to refine the timing of 10 key stratigraphic surfaces and three megasequences. The results have been used to calibrate the interpretation of a margin-scale two-dimensional seismic reflection dataset, and to build megasequence isochore maps, structural restorations and gross depositional environment maps at key time intervals of the margin evolution.Our findings revise the dating of the basal succession drilled by the A2-1 well, indicating that the oldest post-rift sequence penetrated along the margin is late Tithonian age (previously Callovian). Early Central Atlantic carbonate platform sediments passively infilled subcircular-shaped basement topography controlled by the underlying basement structure of thinned continental crust. Barremian–Aptian rifting in the Equatorial Atlantic, caused folding and thrusting of the Demerara Rise, resulting in major uplift, gravitational margin collapse, transpressional structures and peneplanation of up to 1 km of sediment capped by the regional angular Base Albian Unconformity. Equatorial Atlantic rifting led to margin segmentation and the formation of the TMP, where two major unconformities developed during the intra Late Albian and base Cenomanian. These two unconformities are time synchronous with oceanic crust accretion offshore French Guiana and in the Demerara–Guinea transform, respectively. A marine connection between the Central and Equatorial Atlantic is demonstrated by middle Late Albian times, coinciding with deposition of the organic-rich source rock of the Canje Formation (average total organic carbon 4.21%). The succession is variably truncated by the Middle Campanian Unconformity. Refining the stratigraphic framework within the context of the structural evolution and segmentation of the Guyanas margin impacts the understanding of key petroleum system elements.Supplementary material: Photographs of sandstone petrography thin sections (Fig. S1); calcareous nannofossil plates (Fig. S2); palynology reports for A2-1 and FG2-1 (Fig. S3); taxonomy description of new species; sample table and organic geochemistry results (Table S1); and nannofossil distribution charts (Table S2) are available at https://doi.org/10.6084/m9.figshare.c.5280490
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Steemans, Philippe, and Egberto Pereira. "Llandovery miospore biostratigraphy and stratigraphic evolution of the Paraná Basin, Paraguay – Palaeogeographic implications." Bulletin de la Société Géologique de France 173, no. 5 (2002): 407–14. http://dx.doi.org/10.2113/173.5.407.
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Abstract The Paraná Basin covers 1,600,000 km2 including parts of southern Brazil, Paraguay, Uruguay and Argentina. It contains rocks ranging from the Ordovician to Tertiary in age. The present study is focused on the Itacurubí Group, of Llandovery age, from Paraguay. The sedimentology and palynology have been studied in three boreholes from the central part of Paraguay. The Itacurubí Group consists of the Euzébio Ayala, Vargas Peña and Cariy Formations. It corresponds to a complete transgressive – regressive cycle with maximum flooding in the Vargas Peña Formation. The sediments of the group were deposited in a glaciomarine regime and are included in the second order sequence. The palynofacies are dominated by acritarchs and chitinozoans, with miospores rare. Among the latter, cryptospores are most abundant and trilete spores very rare. The miospore assemblages are typical of the Llandovery. The presence of Laevolancis divellomedia and the successive first occurrence of the trilete spore genus Ambitisporites, followed by Archaeozonotriletes, allow the recognition of three biozones: divellomedia I, divellomedia II and chulusnanus. Correlations between the three boreholes based on miospore biostratigraphy and sequence stratigraphy techniques are similar. The miospore assemblages have important palaeogeographic implications: Ordovician / Silurian miospore assemblages, identified in South America are similar to those described in palaeogeographically distinct regions such as China, UK, Belgium, USA etc. This suggests that the phytogeographical differentiation proposed by Gray et al. [1992], with a Malvinokaffric Realm characterised by smooth tetrads and an extra-Malvinokaffric Realm characterised by ornamented tetrads, has to be reconsidered. Clearly, the same miospores are recovered from both regions, no matter if they are close to the palaeo-equator or the palaeo-pole, as is the case in Paraguay. These findings suggest that the same vegetation could survive under various climates. In theory, large oceans could be impassable geographic barriers for land plant miospores larger than 25 μm in diameter. As similar miospore assemblages occur, around the Ordovician – Silurian boundary, on the Gondwana, Avalonia and Laurentia plates, it seems likely that these palaeo-continental plates were in close proximity permitting the expansion of the vegetation through these continents. Therefore, palaeogeographic reconstructions with narrow oceans between the continents better explain early miospore biogeographies in early Silurian times. Maps produced by Dalziel et al. [1994] better explain the diachronism of trilete spore first appearances: Hirnantian in Turkey, Rhuddanian in Saudi Arabia, early Aeronian in Libya, late Aeronian in Paraguay, latest Aeronian in UK, and possibly Telychian in USA. The Baltica plate could possibly have been isolated by a geographic barrier during the Ashgill and the Llandovery, as only simple naked tetrads are known from that plate. The first appearance of the trilete spores in Götland during the early Wenlock could correspond to the end of this geographic isolation. This apparent isolation of the Baltica plate could be due to a lack of data.
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Tesakov, Alexey S., Vadim V. Titov, Alexandra N. Simakova, et al. "Late Miocene (Early Turolian) vertebrate faunas and associated biotic record of the Northern Caucasus: Geology, palaeoenvironment, biochronology." Fossil Imprint 73, no. 3-4 (2017): 383–444. http://dx.doi.org/10.2478/if-2017-0021.
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Abstract Late Miocene continental deposits overlying the Khersonian marine sediments near the city of Maikop bordering the Belaya River (North Caucasus) yielded a diverse biotic record including palynology, ostracods, fresh-water and terrestrial molluscs, fishes, amphibians and reptiles, birds, and mammals. The obtained data indicate predominantly wooded landscapes along the banks of a large fresh-water estuarine or lagoonal basin with occasional connection with the sea. The basin existed in a warm temperate to subtropical climate with a high humidity and an estimated mean annual precipitation above 800 mm. The mammalian assemblage with Hipparion spp., Alilepus sp., Paraglirulus schultzi, Eozapus intermedius, Parapodemus lugdunensis, Collimys caucasicus sp. nov., Neocricetodon cf. progressus, etc. is referable to the early Turolian, MN 11. The data regarding composition and stage of evolution of the small mammal content combined with mostly normal polarity of the fossiliferous deposits, and the age estimates of the upper Khersonian boundary as between 8.6 and 7.9 Ma indicate a plausible correlation with Chron C4n and an age range between 8.1–7.6 Ma.
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Dieni, Iginio, Francesco Massari, and Jacques Médus. "Age, depositional environment and stratigraphic value of the Cuccuru ’e Flores Conglomerate: insight into the Palaeogene to Early Miocene geodynamic evolution of Sardinia." Bulletin de la Société Géologique de France 179, no. 1 (2008): 51–72. http://dx.doi.org/10.2113/gssgfbull.179.1.51.
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Abstract The Cuccuru ’e Flores Conglomerate of eastern Sardinia, a syntectonic unit lining major Cenozoic faults, has been dated by means of palynology at the early middle Lutetian. The deposits were mainly laid down by sediment gravity flows in a subaqueous setting and formed aprons of laterally interfingering debris cones at the toe of active tectonic scarps. Most clasts of rudites are of local provenance. Interestingly, the rudites include minor amounts of clasts of formations which no longer crop out in the area, providing important information on the reconstruction of the original stratigraphic succession and palaeogeography, especially during late Cretaceous and early Palaeogene times. During the Eocene, i.e. in a pre-rotation stage, Sardinia was subjected to the influence of both Alpine and Pyrenean orogenic belts. In eastern Sardinia, the compressional stress field was consistent with that existing in the foreland of the Alpine chain in Corsica, and was expressed by significant wrench tectonics affecting the Variscan basement and the pre-Oligocene sedimentary cover. Deformations associated with major strike-slip faults, such as enéchelon folds and positive flower structures occurring in fault-restraining bends, suggest a shortening direction around N105° (in present-day coordinates). A subsequent wrenching phase of Late Oligocene-Early Miocene age involved reactivation of former “Alpine” faults in a sharply different stress field. This tectonics reflects the intermediate position of the eastern Sardinia belt between the area affected by back-arc stretching (the Sardinian rift and the Liguro-Provençal basin) and the arcuate Apenninic subduction front active in a framework of left-lateral oblique plate convergence.
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Czarnecki, Joanna M., Shahin E. Dashtgard, Vera Pospelova, Rolf W. Mathewes, and James A. MacEachern. "Palynology and geochemistry of channel-margin sediments across the tidal–fluvial transition, lower Fraser River, Canada: Implications for the rock record." Marine and Petroleum Geology 51 (March 2014): 152–66. http://dx.doi.org/10.1016/j.marpetgeo.2013.12.008.
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Rohais, Sébastien, Sébastien Joannin, Jean-Paul Colin, Jean-Pierre Suc, François Guillocheau, and Rémi Eschard. "Age and environmental evolution of the syn-rift fill of the southern coast of the gulf of Corinth (Akrata-Derveni region, Greece)." Bulletin de la Société Géologique de France 178, no. 3 (2007): 231–43. http://dx.doi.org/10.2113/gssgfbull.178.3.231.
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Abstract The southern coast of the gulf of Corinth exhibits syn-rift deposits, giving insights into the first stages of continental extension as well as the geodynamic evolution of the surrounding Aegean region. The stratigraphy (relative position, 3D geometry, dating) of these deposits is still subject to controversies. The syn-rift evolution of the central part of the southern coast of the Corinth rift is revisited, based on new sedimentological and paleontological data. While ostracods analysis provides precise information about the paleoenvironments, recent advances in palynology supply a more accurate chronology. For the first time, we document marine evidences and Pleistocene evidences below the well-known giant Gilbert-type fan deltas of the Corinth rift. The syn-rift fill records a three-phase history: (1) the Lower Group corresponds to continental to lacustrine environments passing up progressively to brackish environments with occasionally marine incursions from before 1.8 Ma to some time after 1.5 Ma, (2) the Middle Group corresponds to giant alluvial fans and to Gilbert-type fan deltas prograding in an alternating marine and lacustrine environment from around 1.5 Ma to some time after 0.7 Ma, and (3) the Upper Group corresponds to slope deposits, Gilbert-type fan deltas and marine terraces indicating the emergence of syn-rift sediments along the southern coast from at least 0.4 Ma to the present day, with alternating marine and lacustrine deposition controlled by the position of the Mediterranean sea level relative to the Rion Strait sill.
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Fitzsimons, Sean J., and Eric A. Colhoun. "Pleistocene glaciation of the King Valley, Western Tasmania, Australia." Quaternary Research 36, no. 2 (1991): 135–56. http://dx.doi.org/10.1016/0033-5894(91)90022-w.
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AbstractAnalysis of the geomorphology, geology, and palynology of deposits in the King Valley permits the identification of four glaciations and two interglaciations and has led to a revision of the Pleistocene stratigraphy of the West Coast Range. The oldest late-Cenozoic deposits in the valley appear to predate glaciation, contain extinct pollen types, and are probably of late-Tertiary age. Overlying deposits of the Linda Glaciation show intense chemical weathering and have a reversed detrital remanent magnetization indicating deposition before 730,000 yr B.P. The highly weathered tills are conformably overlain by organic deposits of the Regency Interglaciation which show a transition from montane scrub rainforest to lowland temperate rainforest. Deposits formed during the later Moore Glaciation record advances of the King Glacier and glaciers from the West Coast Range. A pollen-bearing fluvial deposit records an interstade during this glaciation. On the basis of weathering rinds, amino acid dating, and palaeomagnetism the deposits are estimated to have formed between 730,000 and 390,000 yr B.P. The Moore Glaciation deposits are overlain by sediments of the Henty Glaciation which are believed to predate 130,000 yr B.P. These deposits record multiple advances of the King Glacier and the development of a large lake during an interstade. Deposits of the subsequent Pieman Interglaciation consist of organic fine sands and silts that record a lowland scrub rainforest. Deposits of the last (Margaret) glaciation are restricted to small areas in the northern part of the valley. Although the most recent ice advance culminated after 19,000 yr B.P., evidence of older deposits of the Margaret Glaciation suggests that an early last-glaciation ice advance may have occurred. When combined with earlier studies, the recent work in the King Valley has provided one of the more complete records of Pleistocene glaciation in the Southern Hemisphere. Comparison of the deposits with the record of glaciation in southern South America and Westland, New Zealand, suggests some similarities exist between pre-last-glaciation events and indicates that glacial events in Southern Hemisphere middle latitude areas were synchronous during the last glaciation.
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Jacobson, Stephen R., and Rosemary A. Askin. "Organic stratigraphy and its applications with examples from the North American Western Interior and Antarctica." Paleontological Society Special Publications 6 (1992): 147. http://dx.doi.org/10.1017/s2475262200007073.
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Both insoluble (particulate) and soluble (molecular) sedimentary organic matter carry signatures of physical, chemical, and biological processes. These signatures may reflect (a) primary age-diagnostic, organism-specific, and environmentally-sensitive processes; (b) secondary factors related to mode of transportation, deposition, and preservation; and (c) tertiary agents that indicate post-burial alteration of the organic matter. Application of any or all organic matter data recorded in rocks can be used to solve geologic problems.Organic stratigraphy may be applied to hydrocarbon exploration. Our example uses both particulate and molecular data to reconstruct the age relations of Cretaceous-Lower Tertiary sediments in Wyoming, to determine the age of thrust fault motion, and to demonstrate constraints on the timing of upward petroleum migration to available trapped reservoirs.Another perspective helps establish chronostratigraphic frameworks for correlations of global sea-level change. Our example from Antarctic sediments that span the Cretaceous-Tertiary boundary reflects perturbations in relative sea-level and the consequential changes in the distribution of organic particulates from marine and terrestrial regimes. These data can be compared to age-equivalent data from other parts of the world, and test global sea-level change.Both of these applications demonstrate the versatility of organic matter in solving geologic problems. Data from contemporaneous land plants, freshwater and marine organic-walled micro-organisms provide clues on their lifestyle and subsequent afterlife alteration. Organic stratigraphy represents a long anticipated integration of several paleontological disciplines. It combines aspects of palynology, organic geochemistry, paleobotany, and coal petrography into a coherent science, with an enhanced capability to provide significant applications in the future.
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Tipping, Richard, Deborah Long, Stephen Carter, Donald Davidson, Andrew Tyler, and Brian Boag. "Testing the potential of soil-stratigraphic palynology in podsols." Geological Society, London, Special Publications 165, no. 1 (1999): 79–90. http://dx.doi.org/10.1144/gsl.sp.1999.165.01.06.
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Van Campo, Elise, and Martin Darius Bengo. "Mangrove palynology in recent marine sediments off Cameroon." Marine Geology 208, no. 2-4 (2004): 315–30. http://dx.doi.org/10.1016/j.margeo.2004.04.014.
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Wellman, Charles H. "Palynology of the ‘Lower Old Red Sandstone’ at Glen Coe, Scotland." Geological Magazine 131, no. 4 (1994): 563–66. http://dx.doi.org/10.1017/s0016756800012176.
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Abstract‘Lower Old Red Sandstone’ deposits preserved by cauldron subsidence at Glen Coe, Scotland have hitherto lacked secure biostratigraphical age constraint. A sporomorph assemblage recovered from basal sediments of these deposits permits age determination, despite being highly carbonized. The sporomorph assemblage is correlated with the micrornatus-newportensis Sporomorph Assemblage Biozone, indicating a late early-early late Lochkovian age (early Devonian). Sporomorph assemblages from basal sediments of the ‘Lower Old Red Sandstone’ sequence at nearby Lorne, a suggested correlative of the Glen Coe deposits, are older (latest Pridoli-earliest Lochkovian age). However, the new biostratigraphical data do not preclude the possibility that the Glen Coe and Lorne deposits are lithological correlatives and the basal sediments are diachronous.
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Burgess, Roger, David Jolley, and Adrian Hartley. "Stratigraphic palynology of the Middle–Late Triassic successions of the Central North Sea." Petroleum Geoscience 27, no. 1 (2020): petgeo2019–128. http://dx.doi.org/10.1144/petgeo2019-128.
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Historically, the continental Triassic successions of the Central North Sea have proven difficult to correlate, in part due to the poor palynomorph recovery associated with these sedimentary rocks. The existing framework for correlation is lithostratigraphic and, whilst this has proven effective in United Kingdom Continental Shelf (UKCS) Quad 30 where the mudstone members are well defined, elsewhere in the basin it is more problematic with confident identification of stratigraphic units becoming more difficult. Samples from 32 wells within UKCS Quads 22, 29 and 30, and Norwegian Quads 7, 15 and 16 underwent palynological analysis in which a processing method was utilized that was designed to concentrate palynomorph recovery from Triassic strata.The results of this analysis allowed the proposal of a new zonal scheme consisting of eight biozones. These biozones can then be used to correlate the Triassic successions of the Central North Sea (CNS), helping to provide both clarity and age constraint on previously disputed stratigraphic units, particularly the J-members of the Skagerrak Formation. Within the correlation framework outlined here, the Julius Mudstone Member is shown to be a productive horizon for palynomorph recovery, representing a widespread swamp environment. Here, its lateral extent is defined which is an important consideration when correlating the Triassic stratigraphy of the CNS given that this member can compartmentalize potential reservoirs contained within these successions. The stratigraphic palynology outlined here also allows clarity on the J-member equivalence of some of the informal units previously described within Triassic successions of the CNS, including the Marnock Shale and Heron Shale.
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Ajdanlijsky, George, Annette E. Götz, and André Strasser. "The Early to Middle Triassic continental–marine transition of NW Bulgaria: sedimentology, palynology and sequence stratigraphy." Geologica Carpathica 69, no. 2 (2018): 129–48. http://dx.doi.org/10.1515/geoca-2018-0008.
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AbstractSedimentary facies and cycles of the Triassic continental–marine transition of NW Bulgaria are documented in detail from reference sections along the Iskar river gorge between the villages of Tserovo and Opletnya. The depositional environments evolved from anastomosing and meandering river systems in the Petrohan Terrigenous Group to mixed fluvial and tidal settings in the Svidol Formation, and to peritidal and shallow-marine conditions in the Opletnya Member of the Mogila Formation. For the first time, the palynostratigraphic data presented here allow for dating the transitional interval and for the precise identification of a major sequence boundary between the Petrohan Terrigenous Group and the Svidol Formation (Iskar Carbonate Group). This boundary most probably corresponds to the major sequence boundary Ol4 occurring in the upper Olenekian of the Tethyan realm and thus enables interregional correlation. The identification of regionally traceable sequence boundaries based on biostratigraphic age control is a first step towards a more accurate stratigraphic correlation and palaeogeographic interpretation of the Early to early Middle Triassic in NW Bulgaria.
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Robin, Cecile, Francois Guillocheau, Pascal Allemand, et al. "Echelles de temps et d'espace du controle tectonique d'un bassin flexural intracratonique; le bassin de Paris." Bulletin de la Société Géologique de France 171, no. 2 (2000): 181–96. http://dx.doi.org/10.2113/171.2.181.
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Abstract The Meso-Cenozoic intracratonic flexural Paris Basin is a good tool to determinate the time/space-scales of the tectonic control on the sedimentary record. This study is based on basin-scale 2D sedimentary geometries of the different orders of stratigraphic cycles and on 1D/3D accommodation space measurements (space available for sediments created by subsidence and/or eustatism). Tectonic controls occur at least at three different time-scales: 230 m.y. (basin evolution), 10-40 m.y. (major stratigraphic cycles) and 1-5 m.y. (minor stratigraphic cycles). The evolution of the flexural intracratonic Paris basin can be described as the result of a long term thermal subsidence component with superimpositions of short-term tectonic components, due to intraplate deformations of 10-40 Ma and 1-5 Ma frequencies.
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Kholeif, Suzan E. A. "Palynology and palaeovegetation reconstruction in late Quaternary sediments of the southern Suez Isthmus, Egypt." Journal of African Earth Sciences 40, no. 1-2 (2004): 31–47. http://dx.doi.org/10.1016/j.jafrearsci.2004.07.003.
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Mahesh, S., K. Pauline Sabina, and L. Mahesh Bilwa. "Palynology and depositional facet of lower Permian (Artinskian) sediments from New Majri opencast mine, Wardha basin, India." Journal of the Geological Society of India 83, no. 6 (2014): 697–708. http://dx.doi.org/10.1007/s12594-014-0102-6.
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Radionova, Eleonora, and Larissa Golovina. "Upper Maeotian-Lower Pontian "Transitional Strata" in the Taman Peninsula: stratigraphic position and paleogeographic interpretation." Geologica Carpathica 62, no. 1 (2011): 77–90. http://dx.doi.org/10.2478/v10096-011-0007-x.
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Upper Maeotian-Lower Pontian "Transitional Strata" in the Taman Peninsula: stratigraphic position and paleogeographic interpretationThree sections (Taman, Popov Kamen, and Zheleznyi Rog) of the Upper Maeotian-Lower Pontian sediments of the Taman Peninsula (Eastern Paratethys) have been studied. The sequences represent continuous successions of the Maeotian and Pontian sediments. The transitional Upper Maeotian-Lower Pontian relatively deep-water sediments were formed at the time when Eastern Paratethys was connected with other marine basins. The facies are represented by thin clay layers interbedded with laminated diatomites and contain unusual diatom and nannofossil associations. The small size of coccoliths and the absence of zonal markers indicate that the influx of marine waters took place in the stressed conditions of a restricted basin. Diatom assemblages are more diverse and include the open-marine speciesAzpeitiaaff.komuraeandThalassiosira maruyamicaand marine endemicsActinocyclusaff.paradoxus, Rhizosolenia bezrukovii, Hemiaulussp.,Nitzschia miocenicaof the tropicalNitzschia miocenicaZone and — the index species of nextThalassiosira convexaZone appear in these part of the sections. Three stages of the Mediterranean marine invasion are distinguished; during the first one the connection between basins was rather permanent, for the two others its character became pulsing and not stable. The possible duration of the invasion is estimated from 6.4 to 6.1 Ma and belongs to the Early Messinian — to pre-evaporate deposits and lower part of lower evaporate deposits.
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Diez, José B., Sylvie Bourquin, Jean Broutin, and Javier Ferrer. "The Iberian Permian Triassic ‘Buntsandstein’ of the Aragonian branch of the Iberian range (Spain) in the West-European sequence stratigraphical framework: a combined palynological and sedimentological approach." Bulletin de la Société Géologique de France 178, no. 3 (2007): 179–95. http://dx.doi.org/10.2113/gssgfbull.178.3.179.
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Abstract The Permo-Triassic ‘Buntsandstein’ facies was studied from outcrops in the Aragonian branch of the Iberian range (Zaragoza, Spain). Using an integrated analysis of sedimentological and palynological data, we propose a sequence stratigraphic analysis for the Permo-Triassic deposits in this area. A comparison with the stratigraphical cycles of other parts of the Iberian domain and other peri-Tethyan basins enables us to specify the stratigraphic context of the Lower Triassic in the western European domain and characterize the importance of the Lower Triassic hiatus. The ‘Buntsandstein’ deposits studied here from the Aragonian branch occur in three outcrop areas: Tabuenca-Rodanas, Morata de Jalón and Fombuena. The Permo-Triassic deposits lie unconformably on the Hercynian (Variscan) basement. The ‘Buntsandstein’ facies were attributed to the ‘Detrital Group’ by Arribas [1984], who recognized four informal formations: the Araviana, Tierga, Calcena and Trasobares formations, in ascending stratigraphic order. Based on sedimentological criteria indicating fluvio-lacustrine environments for the Araviana cycle, the basal ‘Buntsandstein’ facies of this area can be attributed to the Permian. The discontinuity observed between the Araviana and Tierga formations, and the palaeobotanical evidence indicating an Anisian age (i.e. Middle Triassic) for the Tierga, suggests a hiatus during the Lower Triassic in this area. The Lower Triassic in Spain and many other parts of western Europe is characterized by fluvial sediments preserved in arid palaeoenvironments, associated with occasional aeolian deposits, and lacking any palaeoflora. At the scale of the western European domain, the onset of Triassic sedimentation would appear mainly in the Olenekian. Stratigraphic continuity between Permian and Triassic non-marine deposits, with sediments attributable to the Induan (lower part of the Lower Triassic), is only observed in the central Germanic Basin. In the Aragonian branch, the first Triassic sediments are dated as Anisian and characterize the retrogradational trend of a major cycle (Tierga – Calcareous Group major cycle) showing the vertical evolution from braided rivers to marine Muschelkalk deposits. At the scale of the west-European domain, the Anisian is always characterized by fluvial and fluvio-lacustrine deposits, with palaeosols, passing upward into marine deposits. Thus, the connection with the open sea was established during the Anisian. In this western Peritethyan domain, the diachronous nature of the Muschelkalk transgression is evident: the onset of Muschelkalk facies occurs during the lower Anisian in the Germanic Basin, the middle Anisian in the eastern part of the Paris Basin and the late Anisian in the Iberian Peninsula.
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López-Merino, Lourdes, Suzanne A. G. Leroy, Amram Eshel, Valentina Epshtein, Reuven Belmaker, and Revital Bookman. "Using palynology to re-assess the Dead Sea laminated sediments – Indeed varves?" Quaternary Science Reviews 140 (May 2016): 49–66. http://dx.doi.org/10.1016/j.quascirev.2016.03.024.
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Craigie, Neil W. "Definition of the Hercynian Unconformity in eastern Saudi Arabia using chemostratigraphy in conjunction with biostratigraphy, sedimentology and lithostratigraphy." Petroleum Geoscience 26, no. 4 (2019): 568–88. http://dx.doi.org/10.1144/petgeo2019-116.
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The following chemostratigraphy study was conducted on Paleozoic sediments encountered in 14 wells in eastern Saudi Arabia. A total of 1500 samples were analysed by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS), with data acquired for 48 elements, ranging from Na to U in the periodic table. The aim was to utilize chemostratigraphy, in conjunction with existing biostratigraphic, lithostratigraphic and sedimentological data, to define the Hercynian Unconformity in each well and to recognize stratigraphic boundaries occurring above and below it. This was necessary as the unconformity eroded to different stratigraphic levels in each well, with Devonian, Silurian and Ordovician sediments found immediately below it in adjacent locations. In the absence of chemostratigraphic, biostratigraphic and sedimentological data, it is often very difficult to define this boundary and others using lithostratigraphy alone as many stratigraphic intervals yield similar gamma-ray (GR) log trends. For example, a low ‘blocky’ GR response is typical of both the Carboniferous Ghazal Member and the Ordovician Sarah Formation. Similarly, both the Silurian Sharawra Member and the Silurian–Devonian Tawil Formation produce a ‘ratty’ GR trend. Each stratigraphic member and formation was found to have distinctive chemostratigraphic, biostratigraphic, sedimentological and/or wireline log signatures.
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Mathews, Runcie P., Suryakant M. Tripathi, Santanu Banerjee, and Suryendu Dutta. "Palynology, palaeoecology and palaeodepositional environment of Eocene lignites and associated sediments from Matanomadh mine, Kutch Basin, western India." Journal of the Geological Society of India 82, no. 3 (2013): 236–48. http://dx.doi.org/10.1007/s12594-013-0146-z.
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Durnikin, D. A., A. V. Matsyura та K. Jankowski. "ОСНОВНЫЕ ЭТАПЫ РАЗВИТИЯ ПРЕДСТАВИТЕЛЕЙ РОДА POTAMOGETON L. (POTAMOGETONACEAE) ВО ФЛОРАХ ВОДОЕМОВ ЗАПАДНОЙ СИБИРИ В КАЙНОЗОЕ ПО ПАЛЕОКАРПОЛОГИЧЕСКИМ И ПАЛИНОЛОГИЧЕСКИМ ДАННЫМ". Biological Bulletin of Bogdan Chmelnitskiy Melitopol State Pedagogical University 6, № 2 (2016): 45–60. http://dx.doi.org/10.15421/201634.
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<p>Palaeobotanical, geomorphological, and paleogeographical data on flora of reservoirs are presented. The structured materials on geomorphology and paleogeography from Paleogene, Neogene and Quaternary deposits of Western Siberia are reported. The stratigraphic complexes linked to tectonic zoning Kulunda and southern Baraba Lowlands are analyzed. The data on the structure-formational zones, distinguished by time of inception, the composition and thickness of the sediments, and nature of the neotectonics are presented. The analysis of paleocarpology and palynology data from the <em>Potamogeton</em> genus as the largest among the aquatic plants of Western Siberia is done. The composition and structure of this genus as an integral part of Tertiary and Quaternary flora of studied reservoirs are characterized, the current composition of this genus is presented. It is proved that the most ancient complexes of the West Siberian Tertiary belong to the upper Eocene, whereas the early Siberian Paleogene is still unknown.<em></em></p>
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Strogen, Dominic P., Karen E. Higgs, Angela G. Griffin, and Hugh E. G. Morgans. "Late Eocene – Early Miocene facies and stratigraphic development, Taranaki Basin, New Zealand: the transition to plate boundary tectonics during regional transgression." Geological Magazine 156, no. 10 (2019): 1751–70. http://dx.doi.org/10.1017/s0016756818000997.
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AbstractEight latest Eocene to earliest Miocene stratigraphic surfaces have been identified in petroleum well data from the Taranaki Basin, New Zealand. These surfaces define seven regional sedimentary packages, of variable thickness and lithofacies, forming a mixed siliciclastic–carbonate system. The evolving tectonic setting, particularly the initial development of the Australian–Pacific convergent margin, controlled geographic, stratigraphic and facies variability. This tectonic signal overprinted a regional transgressive trend that culminated in latest Oligocene times. The earliest influence of active compressional tectonics is reflected in the preservation of latest Eocene – Early Oligocene deepwater sediments in the northern Taranaki Basin. Thickness patterns for all mid Oligocene units onwards show a shift in sedimentation to the eastern Taranaki Basin, controlled by reverse movement on the Taranaki Fault System. This resulted in the deposition of a thick sedimentary wedge, initially of coarse clastic sediments, later carbonate dominated, in the foredeep close to the fault. In contrast, Oligocene active normal faulting in a small sub-basin in the south may represent the most northerly evidence for rifting in southern Zealandia, related to Emerald Basin formation. The Early Miocene period saw a return to clastic-dominated deposition, the onset of regional regression and the southward propagation of compressional tectonics.
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Banks, C. J., and J. A. Winchester. "Sedimentology and stratigraphic affinities of Neoproterozoic coarse clastic successions, Glenshirra Group, Inverness-shire, Scotland." Scottish Journal of Geology 40, no. 2 (2004): 159–74. http://dx.doi.org/10.1144/sjg40020159.
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SynopsisRecords of ancient environments and past basin histories can be preserved in metasedimentary successions, despite their subsequent deformation and metamorphism. In the Central Scottish Highlands SE of Loch Ness, the Garva Bridge Psammite and the Glen Buck Pebbly Psammite Formations (hitherto included within the Glenshirra Subgroup at the base of the Neoproterozoic Grampian Group) represent a continuum of alluvial fan to shallow water sediments, deposited in a SE thinning fan-delta clastic wedge. These sediments, derived from an uplifted granitoid hinterland to the west, contrast with the overlying marine sedimentary rocks of the Corrieyairack Subgroup, which were deposited by sediment gravity flows within a submarine slope setting. The Glen Buck Pebbly Psammite/Garva Bridge Psammite Formations and the Corrieyairack Subgroup represent two genetic stratigraphic sequences divided by a sharp sequence boundary that records a major reorganization in basin architecture. Hence, we propose that the Garva Bridge Psammite and Glen Buck Pebbly Psammite Formations be included within a separate Glenshirra Group, genetically unrelated to either the marine deposits of the immediately overlying Grampian Group or the earlier, locally migmatized (Moinian?) basement to the Central Highlands. The Glenshirra Group thus represents the earliest phase of post-Knoydartian extension, predating the main Dalradian basin development.
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Mildenhall, D. C. "Palynology of predominantly Last Glaciation sediments from the Mangaroa Drillhole, Hutt Valley, New Zealand." New Zealand Journal of Geology and Geophysics 37, no. 1 (1994): 1–9. http://dx.doi.org/10.1080/00288306.1994.9514596.
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Dam, Mai Hoang, Vu Thi Tuyen, Nguyen Tan Trieu, and Nguyen Thi Tham. "Biostratigraphic and petrological characteristics of Cretaceous–Paleogene sediments in the eastern Cuu Long delta." Journal of Petroleum Exploration and Production Technology 11, no. 5 (2021): 2055–73. http://dx.doi.org/10.1007/s13202-021-01156-8.
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AbstractThe basic structure of reservoir models is strongly affected by the stratigraphic interpretation and the properties of reservoir rock. The estimation of the volume of hydrocarbon accumulation will depend on the accuracy of predicting and distributing reservoir quality. Biostratigraphic and sedimentary petrologic results provide geological information to clarify the stratigraphy and properties of sedimentary rocks on the eastern margin of the Cuu Long delta plain trough. On the basis of stratigraphic correlation of the wells and studying the structures of the area, the deposition, thickness of sediments and the ability to correlate with prospect rocks on the southeastern Vietnam continental shelf were determined. The results have identified the basement rock of wells TC-1 and TC-2, which are Cretaceous metasandstones and were deposited in freshwater fluvial environments with high-energy conditions. The upper Paleogene sediments were overlaid directly on the Cretaceous basement rock in the TC-2 well but were completely absent in the TC-1 well. The lithologic composition is mainly feldspathic litharenite sandstone, which is formed in freshwater fluvial and freshwater lacustrine environments. This study provides new data on stratigraphic column of the eastern Cuu Long delta plain. The data show that the age of the sedimentary basement rock is Cretaceous which has not been determined in previous studies. The findings of this study can help for better understanding of the geological development history and the completely stratigraphic column of the Cuu Long delta to correlate with objects that are hydrocarbon accumulation in Cuu Long sedimentary basin in order to improve efficiency in petroleum exploration activities.
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Sincavage, Ryan, Paul M. Betka, Stuart N. Thomson, Leonardo Seeber, Michael Steckler, and C. Zoramthara. "Neogene shallow-marine and fluvial sediment dispersal, burial, and exhumation in the ancestral Brahmaputra delta: Indo-Burman Ranges, India." Journal of Sedimentary Research 90, no. 9 (2020): 1244–63. http://dx.doi.org/10.2110/jsr.2020.60.
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ABSTRACT The stratigraphic record of Cenozoic uplift and denudation of the Himalayas is distributed across its peripheral foreland basins, as well as in the sediments of the Ganges–Brahmaputra Delta (GBD) and the Bengal–Nicobar Fan (BNF). Recent interrogation of Miocene–Quaternary sediments of the GBD and BNF advance our knowledge of Himalayan sediment dispersal and its relationship to regional tectonics and climate, but these studies are limited to IODP boreholes from the BNF (IODP 354 and 362, 2015-16) and Quaternary sediment cores from the GBD (NSF-PIRE: Life on a tectonically active delta, 2010-18). We examine a complementary yet understudied stratigraphic record of the Miocene–Pliocene ancestral Brahmaputra Delta in outcrops of the Indo-Burman Ranges fold–thrust belt (IBR) of eastern India. We present detailed lithofacies assemblages of Neogene delta plain (Tipam Group) and intertidal to upper-shelf (Surma Group) deposits of the IBR based on two ∼ 500 m stratigraphic sections. New detrital-apatite fission-track (dAFT) and (U-Th)/He (dAHe) dates from the Surma Group in the IBR help to constrain maximum depositional ages (MDA), thermal histories, and sediment accumulation rates. Three fluvial facies (F1–F3) and four shallow marine to intertidal facies (M1–M4) are delineated based on analog depositional environments of the Holocene–modern GBD. Unreset dAFT and dAHe ages constrain MDA to ∼ 9–11 Ma for the Surma Group, which is bracketed by intensification of turbidite deposition on the eastern BNF (∼ 13.5–6.8 Ma). Two dAHe samples yielded younger (∼ 3 Ma) reset ages that we interpret to record cooling from denudation following burial resetting due to a thicker (∼ 2.2–3.2 km) accumulation of sediments near the depocenter. Thermal modeling of the dAFT and dAHe results using QTQt and HeFTy suggest that late Miocene marginal marine sediment accumulation rates may have ranged from ∼ 0.9 to 1.1 mm/yr near the center of the paleodelta. Thermal modeling results imply postdepositional cooling beginning at ∼ 8–6.5 Ma, interpreted to record onset of exhumation associated with the advancing IBR fold belt. The timing of post-burial exhumation of the IBR strata is consistent with previously published constraints for the avulsion of the paleo-Brahmaputra to the west and a westward shift of turbidite deposition on the BNF that started at ∼ 6.8 Ma. Our results contextualize tectonic controls on basin history, creating a pathway for future investigations into autogenic and climatic drivers of behavior of fluvial systems that can be extracted from the stratigraphic record.
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Nielsen, M. Houmark. "A lithostratigraphy of Weichselian glacial and interstadial deposits in Denmark." Bulletin of the Geological Society of Denmark 46 (December 20, 1999): 101–14. http://dx.doi.org/10.37570/bgsd-1999-46-09.
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A lithostratigraphic model of Weichselian tills and inter-till deposits in Denmark is erected. Deposits comprise 1) Till, other diamicts and meltwater sediments deposited during glaciated stadials and 2) Interstadial and stadial fluvial, lacustrine and marine sediments deposited under climatic ameliorations and ice free conditions. Stratigraphic successions are correlated using lithological and palaeoecological evidence and they are linked to the marine sequences in northern Denmark named the Skærumhede series. Three stadials with one or more glaciation events succeeding Eemian interglacial conditions have been recognized. The oldest, Ristinge stadial, is most likely from the early Middle Weichselian situated between the Odderade and Moershoofd interstadials. It comprises The Ristinge, Ringshøj and Lovns tills of Baltic origin is found in the eastern and central parts of Denmark. The post-Hengelo, Klintholm stadial from the late Middle Weichselian, is represented by the Baltic Klintholm till found in the easternmost part of the country and possibly the Esrum diamicton in the buried Esrum valley belong to this stadial. The post-Sandnes interstadial, Late Weichselian Jylland stadial comprise the Kattegat Till of Norwegian provenance is found in northern Denmark. It is followed by the Mid Danish, Grenå, Fårup, Store Klinthøj, Himmerland tills of middle Swedish origin, and deposited by the ice-stream which reached the Main Stationary Line from northeasterly directions. The East Jylland and North Sjælland tills of respectively Baltic and Swedish provenance overlie the former tills in eastern Denmark. These are succeeded by the Bælthav Till of Baltic origin which is confined to the Danish islands. Late glacial deposits from the Bølling-Allerød oscillation comprises the upper boundary for Weichselian deposits. The compilation of the stratigraphic model serves the purpose of combining and bringing forward regional and local stratigraphic studies from the past decades and to set up a frame-work for dating the age and duration individual glaciation events and interstadials.
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Gaetani, Maurizio, Eduardo Garzanti, Riccardo Polino, et al. "Stratigraphic evidence for Cimmerian events in NW Caucasus (Russia)." Bulletin de la Société Géologique de France 176, no. 3 (2005): 283–99. http://dx.doi.org/10.2113/176.3.283.
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Abstract The Upper Permian and Triassic sequences of the NW Caucasus present a good record of the Cimmerian events, rather undisturbed by the subsequent Alpine deformations. Original field work with new fossil identifications, microfacies analysis, and sandstone petrography were carried out. During the late Permian, active strike-slip basins were filled by continental clastics successions. Marine ingressions during the latest Permian, led to the formation of sponge reefs and skeletal carbonate ramps. During the Triassic, several siliciclastic wedges were intercalated within the marine carbonate succession. Most important is a conglomerate body made up of serpentinite pebbles of Spathian age (early Triassic), recording the exhumation and erosion of schistose antigorite serpentinites. By the late Anisian a severe deformation affected the Peredovoy (= Fore) Range of the NW Caucasus. Lower Triassic to Anisian sediments deformed also in chevron folds were overlaid with angular unconformity by a siliciclastic, and also volcaniclastic, conglomeratic and arenitic body, up to several hundred meters thick. By the late Ladinian-earliest Carnian, marine sedimentation resumed locally, forming a carbonate ramp during part of the Norian. Towards the end of the Norian, the entire area emerged and was again mildly tilted. The subsequent post-Cimmerian transgression occurred largely during the Middle Jurassic. Consequently, the most important Cimmerian deformations appear to be of early and middle Triassic age.
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Long, Joshua H., Till J. J. Hanebuth, and Thomas Lüdmann. "The Quaternary stratigraphic architecture of a low-accommodation, passive-margin continental shelf (Santee Delta region, South Carolina, U.S.A.)." Journal of Sedimentary Research 90, no. 11 (2020): 1549–71. http://dx.doi.org/10.2110/jsr.2020.006.
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ABSTRACT The Quaternary stratigraphy of the continental shelf offshore of South Carolina consists of stratigraphic units deposited in coastal-plain, shallow marine, and shelfal environments bounded by composite erosional surfaces that developed in response to numerous glacioeustatic cycles and were overprinted by regional uplift. These units are commonly distributed laterally, rather than stacked vertically, a function of the long-term low shelf gradient and the resulting lack of accommodation. Additionally, marine processes such as waves and geostrophic currents can rework both relict and modern sediments across the continental shelf. This study integrates high-resolution geological and geophysical datasets acquired offshore and onshore with existing data onshore into a comprehensive conceptual model describing the Quaternary geologic evolution of the coastal plain and continental shelf within a study area of approximately 8,000 km2. We use seismic facies and core analysis to define stratigraphic units associated with transgressive, regressive, and lowstand systems offshore. Regressive systems include progradational wave- and river-dominated deltaic and shoreface deposits. Lowstand systems consist of a complex network of paleo-incisions produced by regional, Piedmont-draining fluvial systems and smaller coastal plain rivers. Transgressive systems include paleochannel-fill successions dominated by mud-rich, tidally influenced backbarrier deposits, cuspate and linear shelf sand ridges, and transgressive sand sheets and shoals. The low-accommodation setting of the continental shelf influences the stratigraphic record in several ways: 1) the geometry of progradational coastal lithosomes, 2) the development of composite allogenic erosional surfaces, 3) the deposition of widespread, thin transgressive sand sheets, and 4) the restriction of thicker transgressive deposits to paleo-incisions. In this setting, the use of a bounding surface scheme that is hierarchical is preferable to the more common sequence stratigraphic or allostratigraphic convention for several reasons: 1) major erosional bounding surfaces are commonly amalgamated; 2) lower-order surfaces capture internal variability, which is key to the genetic interpretation of stratigraphic units, and 3) stratal stacking patterns typically used to define a sequence stratigraphic framework are rare.
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Goričan, Špela, Josip Halamić, Tonći Grgasović, and Tea Kolar-Jurkovšek. "Stratigraphic evolution of Triassic arc-backarc system in northwestern Croatia." Bulletin de la Société Géologique de France 176, no. 1 (2005): 3–22. http://dx.doi.org/10.2113/176.1.3.
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Abstract Middle Triassic arc-related extensional tectonics in the western Tethys generated a complex pattern of intra-and backarc basins. We studied volcano-sedimentary successions of subsided continental-margin blocks (Mts. Žumberak and Ivanščica) and of dismembered incomplete ophiolite sequences interpreted as remnants of a backarc basin (Mts. Medvednica and Kalnik) in northwestern Croatia. We dated the successions with radiolarians, conodonts, foraminifers, algae, and sponges. The continental margin experienced a phase of accelerated subsidence in the late Anisian that was approximately coincident with the onset of intermediate and acidic volcanism; pelagic sediments with volcaniclastics accumulated atop subsided carbonate platforms. These relatively shallow basins were later infilled completely by prograding platforms in the late Ladinian-Carnian. In the backarc basin, sea-floor spreading initiated near the Anisian-Ladinian boundary and continued into the late Carnian. Pillow basalts were erupted and interlayered with radiolarian cherts and shales. The studied area was a part of a larger Triassic arc-backarc system preserved in the southern Alps, Alpine-Carpathian Belt, Dinarides, and Hellenides. Volcano-sedimentary successions of Mts. Medvednica and Kalnik are relics of the Meliata-Maliak backarc basin. In comparison to other previously dated oceanic remnants of this system, the longest continuous sea-floor spreading is now documented in one restricted tectonic unit.
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Alvan, Aldo A., Yacory F. Bustamante, Elvis A. Sánchez, and Mirian I. Mamani. "Arquitectura estratigráfica, paleogeografía y proveniencia sedimentaria de las rocas cenozoicas del sur de Perú (Tacna, 18° S)." Andean Geology 47, no. 2 (2020): 351. http://dx.doi.org/10.5027/andgeov47n2-3168.
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The Cenozoic rocks lying in the Province of Tacna (18° S), southern Perú, represent approximately 600 m of stratigraphic thickness. This stacking groups the Sotillo (Paleocene), Moquegua Inferior (Eocene), Moquegua Superior (Oligocene), Huaylillas (Miocene) and Millo formations (Pliocene), and these are the sedimentary fill of the Moquegua Basin. The sediments of the three latter formations are organized into nine sedimentary facies and five architectural elements. Their facies associations suggest the existence of an ancient highly channelized multi-lateral fluvial braided system, with upward increase of pyroclastic and conglomeratic depositions. The heavy mineral spectra make each lithostratigraphic unit unique and distinguishable, being the sediments of the Moquegua Superior Formation rich in garnets, titanites and zircons; while the sediments of the Huaylillas and Millo formations in clinopyroxenes. This mineral arrangement becomes an excellent tool for stratigraphic correlations between outcrops and subsurface stratigraphy (by means of well cores studies) and allow to sketch out a new stratigraphic framework and a complex of rocky blocks bounded by normal faults, often tilted. The sediment mineralogy also suggests that the rocks conforming the Western Cordillera were the main source of sediments for the Moquegua Basin in Tacna. In this context, the detritus of the Moquegua Superior Formation derives mainly from the erosion of the rocks forming the Coastal Basal Complex (Proterozoic), the Ambo Group (Carboniferous) and the Junerata/Chocolate Formation (Early Jurassic). The Huaylillas Formation is a pyroclastic and sedimentary unit which components derived mainly from the Huaylillas volcanism (Miocene) and partly from the denudation of the Toquepala Group (Late Cretaceous). The Huaylillas Formation widely contrasts to the underlying Moquegua Superior Formation due its mineralogy and facies. Finally, the detritus of the Millo Formation derived mostly from the rocks forming the Barroso Formation (Pliocene), and their facies represent a higher contrast in relation to the underlying units due its notorious conglomerate facies.
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Gnibidenko, Z. N., V. S. Volkova, O. B. Kuz’mina, Zh A. Dolya, I. V. Khazina, and A. V. Levicheva. "Stratigraphic, paleomagnetic, and palynological data on the Paleogene–Neogene continental sediments of southwestern West Siberia." Russian Geology and Geophysics 52, no. 4 (2011): 466–73. http://dx.doi.org/10.1016/j.rgg.2011.03.009.
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Rundić, Ljupko, Meri Ganić, Slobodan Knežević, and Ali Soliman. "Upper Miocene Pannonian sediments from Belgrade (Serbia): new evidence and paleoenvironmental considerations." Geologica Carpathica 62, no. 3 (2011): 267–78. http://dx.doi.org/10.2478/v10096-011-0021-z.
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Upper Miocene Pannonian sediments from Belgrade (Serbia): new evidence and paleoenvironmental considerationsThe Late Miocene sublittoral marls of the Pannonian Stage (the long-lived Lake Pannon) were studied. From neotectonic point of view, the investigated area represents a natural border between two different morphostructural domains: the Pannonian Basin to the north and the Peri-Pannonian Realm to the south. More than 20 mollusc and 34 ostracod species were identified which indicate the upper part of the Lower Pannonian and the lower part of the Middle Pannonian ("Serbian") predominantly. The identified dinoflagellate cyst assemblage (21 taxa) hinders assignment of the studied samples to a Pannonian substage but supports the high endemism of the Pannonian flora. The lithostratigraphical, paleontological, and paleoecological analyses indicate a mesohaline (8-16 ‰), sublittoral (<90 m deep) environment of the early Lake Pannon. The estimated stratigraphic range for the investigated deposits is 9.8-11.4 Ma.
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Josenhans, H. W., J. Zevenhuizen, and R. A. Klassen. "The Quaternary geology of the Labrador Shelf." Canadian Journal of Earth Sciences 23, no. 8 (1986): 1190–213. http://dx.doi.org/10.1139/e86-116.
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The regional distribution of glacial and postglacial sediments on the Labrador Shelf was mapped by medium- and high-resolution seismics and shows a succession of tills that extend to the continental shelf edge at approximately 600 m. The uppermost of these tills is less laterally extensive and does not occur on the Labrador Shelf bank tops in water depths less than 160 m. We infer that the last glacial episode was less extensive than the preceding ones. Glaciomarine stratified silts and postglacial muds are found overlying the upper till in the deep basins that separate the banks. The upper till, glaciomarine silts, and postglacial muds are interpreted to constitute one complete deglacial cycle. Radiocarbon age determination suggests this deglacial sequence began at approximately 20 000 years BP. On the northernmost Labrador Shelf and Hudson Strait, seismic evidence indicates a late glacial readvance locally deposited a till that overlies the glaciomarine sediments associated with the last glacial advance on the Labrador Shelf. The stratigraphic position of this Hudson Strait till suggests the local readvance occurred at approximately 8000 years BP. The acoustic stratigraphic framework (data) is ground truthed by a regionally extensive piston core and grab sample network. Multidisciplinary analysis of these sediment samples included X-ray, textural, geotechnical, paleontological, lithological, trace-element, and 14C analyses. The results confirm the acoustic interpretations and show that each of the stratigraphic units defined have unique and regionally consistent properties. Geotechnical analyses from the upper till indicate low shear strengths (± 25 kPa) and low to normal consolidation ratios (0.8–2.8), which we interpret to indicate deposition under low basal loading as a result of hydrostatic support on an ice shelf in a marine setting. Provenance studies on the sands and gravels from each of the stratigraphic units of the last deglacial sequence (i.e., till, glaciomarine silts, postglacial muds) indicate that the till is mostly derived from mainland Labrador and transported by an easterly ice flow. Since limestone outcrops are rare to absent on the Labrador mainland and continental shelf, high limestone concentrations (up to 80%) within the glaciomarine sediments that overlie the upper till indicate a northern and distal source for that unit. We interpret an active ice margin overlying the Paleozoic limestone outcrops in Hudson Strait and Ungava Bay as being the dominant source for the glaciomarine silts. The absence of limestone within the postglacial muds that overlie the glaciomarine silts indicates a significant change in provenance, which we attribute to the disappearance of the active ice margin over the limestone terranes. The depositional style and sedimentary structures within the glaciomarine silts indicate low bottom currents and a uniform rain out of ice-rafted (limestone) debris that extends to the southernmost part of the Labrador Shelf. The depositional style of the postglacial muds indicates a significant increase in bottom currents, with deposition restricted to the deep basins. We suggest these increased currents resulted from the disappearance of the Hudson Strait ice barrier, which allowed the Canadian current to develop and combine with the west Greenland current. This combination of currents occurred at approximately 8000 years BP and marks the inception of the Labrador current, which presently traverses the Labrador Shelf.
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Dolding, Philip J. D. "Palynology of the Marambio Group (Upper Cretaceous) of northern Humps Island." Antarctic Science 4, no. 3 (1992): 311–26. http://dx.doi.org/10.1017/s0954102092000476.
Full textAbstract:
Palynological analyses of the Marambio Group sediments of Humps Island (Santa Marta and López de Bertodano formations) indicates that there is minor displacement across a prominent NW–SE trending normal fault which passes beneath the southern bluff. No major compositional differences were perceived between the palynomorph assemblages either side of the fault. A late Campanian age is suggested for both sequences, based on comparison with Australasian dinoflagellate cyst zonations. A new species of the dinoflagellate cyst Bourkidinium has been recorded from strata on either side of the fault. A significant number of recycled Permian and Early Cretaceous palynomorphs were recorded. Most are miospores and exhibit significant variation in preservational states, implying derivation from several sources. More thermally mature Permian gymnosperm pollen is most likely derived from the nearby Trinity Peninsula Group, exposed on the Antarctic Peninsula. The source of the relatively well preserved Permian pollen is problematic.
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Jansen, H. S. M. "Reply to ‘Comment on The geometry and stratigraphic position of the Maassluis Formation (western Netherlands and south-eastern North Sea)’." Netherlands Journal of Geosciences - Geologie en Mijnbouw 84, no. 1 (2005): 53. http://dx.doi.org/10.1017/s0016774600022915.
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In their comment, Wesselingh et al. say that pronounced glacioeustacy renders the detailed discussions about age intervals obsolete and that they fail to see the application of the Haq curves for age estimates in the Maassluis Formation can make much sense. We would argue the following: - Eustacy and sediment supply are the driving forces behind sequence formation and configuration. As our model shows, the overall picture of the Pliocene/Pleistocene along our transect is one of an outbuilding system, going from open marine to terrestrial deposits, which is a classic sequence stratigraphic configuration.- The lower part of the Maassluis Formation in the Noordwijk borehole lies below an unconformity and consists of open marine sediments as opposed to the coastal sediments of the upper part. Since it is the normal transition over a sequence boundary, there is reason to speculate about which sequences we are looking at here and what their age is. There is a large sedimentary wedge to the west of Noordwijk that is missing in the Noordwijk borehole.- The glacial-interglacial cycles Meijer et al. (in press) refer to are likely to be better expressed in the coastal part of the formation, i.e. from ca. 2.55 Ma. This is also the part of the formation where micro-vertebrates will be found, not the (older) marine part. These cycles do not alter the overall sequence stratigraphic model, they add a climatic overprint of smaller sedimentary cycles.
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Knipping, M. "Early and Middle Pleistocene pollen assemblages of deep core drillings in the northern Upper Rhine Graben, Germany." Netherlands Journal of Geosciences - Geologie en Mijnbouw 87, no. 1 (2008): 51–65. http://dx.doi.org/10.1017/s0016774600024045.
Full textAbstract:
AbstractRecent core drillings, carried out during water-economic exploration in the area of Mannheim/Ludwigshafen/Schifferstadt (Rhine-Neckar region, Germany), have produced a more differentiated stratigraphic division of the Pleistocene sediments of the northern Upper Rhine Graben. Pollen analytical investigations as well as malacological, heavy mineral, palaeomagnetic and lithological research have led to a stratigraphic reinterpretation of the gravel layers and intermediate horizons. Based on the results of the pollen analyses, the Mannheim interglacial period in the upper intermediate horizon (Oberer Zwischenhorizont, OZH) cannot be assigned to the Eemian as stated earlier. The occurrence ofFagus, CeltisandAzolla,along with the results of malacological analyses, indicate a Cromerian age for the Mannheim Interglacial. In addition, a pollen sequence from a different interglacial in the core sediments from Schifferstadt could also be assigned to the Cromerian. The Schifferstadt Interglacial is divided into a lower optimum phase with high values ofUlmus, QuercusandCoryluswhileCarpinusis completely absent, and an upper optimum phase with low values ofCarpinus.Fagusis absent in the whole sequence. The OZH comprises not only the two interglacial pollen sequences described above but also parts of at least four Middle Pleistocene Interglacials. In the lower part of the drillings in Schifferstadt and Ludwigshafen, which are assigned to the Early Pleistocene, pollen assemblages withFagusare likely to correlate with parts of the Tiglian A substage. There is a clear change to a Tertiary type of pollen flora at 91 m at Schifferstadt and at 186 m in Ludwigshafen.
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Crombez, Vincent, Sébastien Rohais, François Baudin, Benoit Chauveau, Tristan Euzen, and Didier Granjeon. "Controlling factors on source rock development: implications from 3D stratigraphic modeling of Triassic deposits in the Western Canada Sedimentary Basin." Bulletin de la Société géologique de France 188, no. 5 (2017): 30. http://dx.doi.org/10.1051/bsgf/2017188.
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The recent development of unconventional resources has triggered a regain of interest for source-rocks. The presence of hydrocarbons in these unconventional systems is generally associated with organic-rich sediments. This study aims at better understanding the factors controlling the accumulation of marine organic matter at basin scale, using a process-based approach. This work focuses on the Montney, Doig and Halfway Formations (Lower and Middle Triassic, Alberta and British Columbia, Canada). Recent studies show that the Triassic strata of the Western Canada sedimentary basin can be considered as a transitional period between the Paleozoic passive margin and the Jurassic foreland basin. Based on a 3D regional stratigraphic architecture and on a description of the organic rich interval distribution, a process-based numerical model (DionisosFlow and DORS) has been used to simulate the stratigraphic evolution of the Montney, Doig and Halfway Formations and reproduce the organic distribution in these formations. This modeling approach allowed us to test different scenarios of primary productivity and basin restriction and discuss the regional controls on organic matter accumulation such as dynamic of anoxia or dilution of organic matter by detrital sediments. The reconstruction of the stratigraphic architecture emphasizes a major drop of the water discharge in the basin. In the absence of any evidence supporting a link with a climate change, the drop in water discharge suggests a major modification of the drainage area of the basin, potentially associated with the early stage of the cordilleran orogeny and foreland basin evolution. The numerical simulation also shows that the primary productivity rates in the Montney and Doig Formations are characteristic of a coastal area and that a basin restriction is required to account for the level of anoxia observed in the studied Formations. Lastly, this study investigates the regional controls on organic matter accumulation and emphasizes the impact of regional paleogeographic and geodynamic evolution on the dynamic of anoxia and on the dilution.
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Gozhyk, Petro, Vladimir Semenenko, Aida Andreeva-Grigorovich, and Ninel Maslun. "The correlation of the Neogene of Central and Eastern Paratethys segments of Ukraine with the International Stratigraphic Chart based on planktonic microfossils." Geologica Carpathica 66, no. 3 (2015): 235–44. http://dx.doi.org/10.1515/geoca-2015-0022.
Full textAbstract:
Abstract Detailed analysis of microplankton occurrence (planktonic foraminifera, nannoplankton, dinocysts) in Neogene sediments situated at the north-western and south-eastern margins of Ukraine enabled us to distinguish 10 associations of oceanic plankton which specified the relative age of lithostratigraphic units of various regions and were used as correlation levels within the Central and Eastern Paratethys strata. Moreover, an attempt to correlate regional stages and the International Stratigraphic Chart (ISC) is performed. The Oligocene/Miocene boundary (of ISC) represented by the correlation level I was placed within the Central Paratethys regional stage Egerian and in the middle part of the Eastern Paratethys regional stage Caucasian s.l. The latter regional stage is subdivided by the correlation level into two substages: Lower Caucasian (Chattian of ISC) and Upper Caucasian (Aquitanian of ISC). The correlation level II was placed within the upper part of the Eggenburgian and lower part of the Batisifonian (Sakaraulian) regional stages and is correlated approximately with the middle part of the Burdigalian (of ISC). The base of the Middle Miocene is marked by level IV and was recognized only in deposits of the Eastern Paratethys belonging to the Tarkhanian regional stage. This level corresponds to the lowermost Badenian and Langhian (of ISC) stages. Correlation level V is traced in the Konkian sediments of the Eastern Paratethys and is compared with the Upper Badenian and Lower Serravalian (of ISC) stages. Level VI at the Middle/Upper Miocene boundary is situated in the middle part of the Bessarabian regional substage of the Eastern Paratethys and enables its correlation with the Serravallian/Tortonian boundary (of ISC). Level VII is recognized in the Baherovo Member (Meotian stage), while level VIII is fixed at the top of the Meotian regional stage in the Azov and Black Seas, Crimea and adjacent region named Northern Prichornomorye. Both these levels are also identified in the Berezhnytsya Formation of the Eastern Carpathian Foredeep. Correlation of these sediments is similar to the correlation of sediments of Lake Pannon (Pannonian regional stage), hence with the Tortonian stage (of ISC). Level IX was recognized in sediments of the Azov Member belonging to the Kimmerian regional stage of the Eastern Paratethys and represents the top of the Miocene strata. Level X occurs within the Taman Member of the Black Sea shelf and is correlated with the upper part of Kuyalnikian regional stage; corresponding to the Pliocene/Pleistocene boundary.
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Makarova, A. L. "Middle–Upper Cambrian Trilobites of the Genus Nganasanella Rosova, 1963 and Their Stratigraphic Significance." Russian Geology and Geophysics 62, no. 07 (2021): 746–64. http://dx.doi.org/10.2113/rgg20194101.
Full textAbstract:
Abstract —This paper presents a revision for the genus Nganasanella Rosova, 1963, first described in the stratotype of the Kulyumbean Regional Stage of the Kulyumbe River section (northwest of the Siberian Platform). This section is typical of the upper Cambrian sediments of the Kotuy–Igarka facies region, formed in a shallow marine shelf. As shown by the study, the genus comprises seven species. The species N. nganasanensis Rosova, 1963 (type species), N. tavgaensis Rosova, 1963, N. glabella (Kobayashi), 1943, N. granulosa Rosova et Makarova, 2009, and N. vernacula Rosova et Makarova, 2009 are found in the Siberian Platform. The species N. australica sp. nov. occurs in northeastern Australia. The species N. trisulcatus (Ergaliev), 1980 is widespread in southern Kazakhstan. Some species (N. granulosa and N. vernacula) are found in open marine facies sediments along with the cosmopolitan agnostid species Glyptagnostus reticulatus (Angelin), 1851, serving as a marker of the lower boundary of upper Cambrian strata in the International Chronostratigraphic Chart and the General Stratigraphic Chart of Russia. The species N. trisulcatus and N. australica are found slightly above Glyptagnostus reticulatus. Representatives of the genus Nganasanella are a link between strata of different facies containing different trilobite associations. Their stratigraphic position can serve as an argument for the correlation of the Kulyumbean Regional Stage with units containing Glyptagnostus reticulatus, i.e., the Omnian and Idamean regional stages, the lower parts of the Kutugunian Horizon and the Sakian Regional Stage, and the Paibian Stage of the International Chronostratigraphic Chart.
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John-Joe, Traynor. "Arenig sedimentation and basin tectonics in the Harlech Dome area (Dolgellau Basin), North Wales." Geological Magazine 127, no. 1 (1990): 13–30. http://dx.doi.org/10.1017/s0016756800014138.
Full textAbstract:
AbstractArenig (Ordovician) clastic sediments crop out in the Harlech Dome region (North Wales), and are placed in a single stratigraphic unit: the Allt Lwyd Formation. This unit records a marine transgression onto an erosion surface produced during late Tremadoc arc volcanicity. Four discrete petrofacies are denned, and reflect differing proportions of detritus derived from Tremadoc-type basic-intermediate igneous rocks, and the local sedimentary basement. Initial shallow marine siliciclastic sandstones and conglomerates are overlain by extensive deep water mud-rich units. These generally shallow up into a complex arc-apron deposit, with sediments derived from the eroding Tremadoc arc, as well as from similar, synchronous volcanics. Predominantly epiclastic sandstones and conglomerates were deposited in deltaic and tidal environments in an arc-apron complex, and capped by condensed mudstones and an ironstone, deposited as sea level rose across these systems. Sediments were ponded in north–south orientated troughs and derived from uplifted blocks. Facies and petrofacies distribution were controlled by syn-sedimentary north-south and northeast–southwest faults. The Allt Lwyd Formation was ponded in a fault-controlled basin (the Dolgellau Basin), one of a series of interconnected sub-basins flooded by the Arenig transgression. The sediments preserved reflect deposition during the transgression of a volcanic arc, prior to the extrusion of marginal basin-type volcanics.
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Koppelhus, E. B., and D. R. Braman. "Upper Cretaceous palynostratigraphy of the Dry Island areaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus." Canadian Journal of Earth Sciences 47, no. 9 (2010): 1145–58. http://dx.doi.org/10.1139/e10-068.
Full textAbstract:
The overall palynology of the upper Horseshoe Canyon Formation to lower Scollard Formation within the Edmonton Group is reviewed providing new insights into biostratigraphic relationships for the interval, including the recognition of unconformities in the stratigraphic package. The palynomorph recovery from the Horseshoe Canyon Formation and overlying units documents a number of significant events that allow the subdivision of the section. The Albertosaurus bonebed occurs within the lower Maastrichtian portion of the Edmonton Group. The bonebed is situated just below the base of the Scollardia trapaformis Palynomorph Zone, an important marker assemblage that has been documented from areas of the Yukon, Northwest Territories, Alberta, and Saskatchewan. This indicates that the bonebed lies at the top of the Mancicorpus vancampoi Zone. The transition between the zones is marked by a colour change in the sediments, the appearance of coals and organic-rich sediments above the transition, a decrease in numbers of vertebrate fossils, and the appearance of new pollen species. It is inferred that the observed changes reflect a climatic switch from dry to wetter conditions. At a large scale, palynomorph assemblages across this transition do not clearly indicate marked differences that can be attributed to the climatic change, with the exception of the appearance of Scollardia trapaformis and Mancicorpus gibbus in the assemblages. On a microscale of a few metres, there are changes in relative abundance of plant groups.
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SAEIN, ALI FARZIPOUR, and ZAHRA TAJMIR RIAHI. "Controls on fracture distribution in Cretaceous sedimentary rocks from the Isfahan region, Iran." Geological Magazine 156, no. 06 (2017): 1092–104. http://dx.doi.org/10.1017/s0016756817000346.
Full textAbstract:
AbstractIn this study, relationships between fracture patterns, lithology, thickness, diagenetic processes and grain size are evaluated within Cretaceous sediments in two sections of Dizlu and Kolah Ghazi of Isfahan. This study area was selected based on its outcrops of different rock units and its well-developed tectonic fractures. The fracture patterns within stratigraphic units of these sections are studied using geometrical and statistical analyses. This study finds that variable fracture spacing and fracture spacing ratios can be affected by lithology, thickness, grain size of sediments and diagenetic processes. A study of fracture stratigraphy based on fracture pattern evaluation within different cropped-out sedimentary rocks can be used to improve understanding of the same types of sedimentary rock units below the surface or throughout other sedimentary basins. Consequently, this could improve information regarding storage and fluid flow pattern throughout sedimentary rocks in different regions, even for subsurface purposes.
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Rooksby, S. K. "The Miller Field, Blocks 16/7B, 16/8B, UK North Sea." Geological Society, London, Memoirs 14, no. 1 (1991): 159–64. http://dx.doi.org/10.1144/gsl.mem.1991.014.01.20.
Full textAbstract:
AbstractThe Miller Oil Field is located on the western margin of the South Viking Graben in UKCS Blocks 16/7b and 16/8b. The oil is trapped in Upper Jurassic turbidite sands shed from the Fladen Ground Spur via the Brae complex submarine fan systems. The reservoir sands are of good quality with an average porosity of 16% and permeabilities occasionally in excess of 1 Darcy. The trap is formed within a subtle structural-stratigraphic combination. Overlying slow velocity Lower Cretaceous sediments produce a time flat which, after depth conversion, produces a 3-way dip closed feature. The trap is completed by stratigraphic pinchout of the reservoir sands to the northwest. The most recent (1985) seismic data allow the top reservoir reflector to be picked directly, which was not the case during the exploration and appraisal phase, when only the Top Kimmeridge Clay seismic pick could be made. The estimate of recoverable hydrocarbons is currently 300 MMBBL of oil and 570 BCF of gas. Development drilling commenced early in 1989. No results are yet available.
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Palzer-Khomenko, Markus, Michael Wagreich, Wolfgang Knierzinger, et al. "A calcite crisis unravelling Early Miocene (Ottnangian) stratigraphy in the North Alpine–Carpathian Foreland Basin: a litho- and chemostratigraphic marker for the Rzehakia Lake System." Geologica Carpathica 69, no. 4 (2018): 315–34. http://dx.doi.org/10.1515/geoca-2018-0019.
Full textAbstract:
Abstract Within the Lower Austrian part of the North Alpine Foreland Basin (NAFB), up to 1000 m of sediments were deposited throughout the Ottnangian (Early Miocene, Burdigalian). According to homogeneous compositions and sparse biostratigraphic resolution, a consistent stratigraphic concept from the basin margins into the foreland depocenter was still lacking. New investigations on several deep drill cores throughout the basin provide comprehensive sedimentological, mineralogical, chemical and micropaleontological data. A calcite poor, fossil- and pyrite-free, smectite-rich, up to 800 m thick interval was identified and correlated to the time interval of the late Ottnangian brackish Rzehakia Lake System. For this section, we introduce the term Calcite Minimum Interval (CMI). We define the onset of the CMI by a sharp decrease of calcite contents and the disappearance of autochthonous (and reworked) calcareous nannofossils. We define the termination of the CMI by the permanent increase of pyrite contents and the reappearance of calcareous nannofossils. The CMI as a litho- and chemostratigraphical marker for the Rzehakia Lake System constitutes a stratigraphic key horizon. Within the NAFB in Lower Austria, its onset corresponds to the middle/upper Ottnangian transition while its termination correlates roughly to the Ottnangian / Karpatian boundary. This allows a precise definition, identification and correlation of (upper) Ottnangian stratigraphic units of the NAFB. For the central basinal parts of the Rzehakia Lake System, we introduce the new lithostratigraphic term Wildendürnbach Formation which correlates to the marginal Traisen Formation.