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1
Halverson, Galen P., Susannah M. Porter, and Timothy M. Gibson. "Dating the late Proterozoic stratigraphic record." Emerging Topics in Life Sciences 2, no. 2 (July 2018): 137–47. http://dx.doi.org/10.1042/etls20170167.
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The Tonian and Cryogenian periods (ca. 1000–635.5 Ma) witnessed important biological and climatic events, including diversification of eukaryotes, the rise of algae as primary producers, the origin of Metazoa, and a pair of Snowball Earth glaciations. The Tonian and Cryogenian will also be the next periods in the geological time scale to be formally defined. Time-calibrating this interval is essential for properly ordering and interpreting these events and establishing and testing hypotheses for paleoenvironmental change. Here, we briefly review the methods by which the Proterozoic time scale is dated and provide an up-to-date compilation of age constraints on key fossil first and last appearances, geological events, and horizons during the Tonian and Cryogenian periods. We also develop a new age model for a ca. 819–740 Ma composite section in Svalbard, which is unusually complete and contains a rich Tonian fossil archive. This model provides useful preliminary age estimates for the Tonian succession in Svalbard and distinct carbon isotope anomalies that can be globally correlated and used as an indirect dating tool.
2
Wu, He Yuan, and Bin Hao. "Third-Order Sequence Division of Yunmengshan and Baicaoping Formation of Proterozoic in Yuxi District of China: an Example from Xiatang Profile in Lushan." Advanced Materials Research 998-999 (July 2014): 1492–97. http://dx.doi.org/10.4028/www.scientific.net/amr.998-999.1492.
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There are controversies on the Proterozoic stratigraphic genesis, division, correlation and palaeogeographical evolution of western Henan in China. Based on the basic description of sedimentary facies, Yunmengshan and Baicaoping formation of Proterozoic typical section in western Henan is divided into 4 third-order sequences. Sequence stratigraphy framework which reflects sedimentary and overlap is established with basis of two kinds of facies-change surface and two kinds of diachrononism in stratigraphical records. Although chronostratigraphic belonging of Precambrian strata is controversial and Precambrian sequential stratigraphic study is tremendously challenging, the establishment of sequence stratigraphy framework of proterozoic Yunmengshan and Baicaoping formation in western Henan provides actual data to reshape palaeogeographic pattern of Palaeoproterozoic North China craton. What is more, it becomes a typical example of characteristics and exploration of stratigraphic accumulation under the background of tidal action.
3
Martins-Neto, Marcelo A. "Sequence stratigraphic framework of Proterozoic successions in eastern Brazil." Marine and Petroleum Geology 26, no. 2 (February 2009): 163–76. http://dx.doi.org/10.1016/j.marpetgeo.2007.10.001.
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4
Ming, Yan, Liu Yingjun, and Ma Dongsheng. "Stratigraphic geochemistry of Upper-Middle Proterozoic Suberathem in northern Guangxi, China." Chinese Journal of Geochemistry 14, no. 3 (July 1995): 231–42. http://dx.doi.org/10.1007/bf02842046.
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5
Roscoe, S. M., and K. D. Card. "The reappearance of the Huronian in Wyoming: rifting and drifting of ancient continents." Canadian Journal of Earth Sciences 30, no. 12 (December 1993): 2475–80. http://dx.doi.org/10.1139/e93-214.
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Striking stratigraphic and sedimentological similarities between the Early Proterozoic Huronian Supergroup of the Canadian Shield and the Snowy Pass Supergroup of Wyoming suggest that they were deposited in a single, broad, epicratonic basin developed atop a large Archean continent that included the Superior and Wyoming geological provinces. Breakup of the continent after the 2.2 Ga intrusion of widespread gabbro sheets and dykes resulted in the separation of the Archean Superior and Wyoming cratons and their Early Proterozoic covers. These crustal fragments were subsequently reassembled during Early Proterozoic (~1.85 Ga) orogenesis, the end result being the present 2000 km separation of the Huronian and Snowy Pass supergroups and their Archean basements.
6
Ansdell, Kevin M., T. Kurtis Kyser, Mel R. Stauffer, and Garth Edwards. "Age and source of detrital zircons from the Missi Formation: a Proterozoic molasse deposit, Trans-Hudson Orogen, Canada." Canadian Journal of Earth Sciences 29, no. 12 (December 1992): 2583–94. http://dx.doi.org/10.1139/e92-205.
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The Missi Formation in the Flin Flon Basin forms part of a discontinuous series of molasse-type sediments found throughout the Early Proterozoic Trans-Hudson Orogen in northern Saskatchewan and Manitoba. The Flin Flon Basin contains a sequence of proximal-fan to braided-stream fluvial conglomerates and sandstones, which unconformably overlie subaerially weathered Amisk Group volcanic rocks. Stratigraphic way-up indicators have been preserved, even though these rocks have undergone greenschist-facies metamorphism and polyphase deformation. The sedimentary rocks are crosscut by intrusive rocks, which provide a minimum age of sedimentation of 1840 ± 7 Ma.Detrital zircons from each of the six stratigraphic subdivisions of the Flin Flon Basin were analyzed using the single-zircon Pb-evaporation technique. Euhedral to slightly rounded zircons dominate each sample, and these zircons give ages of between about 1854 and 1950 Ma. The Missi sediments were thus deposited between 1840 and 1854 Ma. Possible sources for the detrital zircons are Amisk Group felsic volcanic rocks and post-Amisk granitoid rocks and orthogneisses in adjacent domains within the Trans-Hudson Orogen. However, the immature character of the sedimentary rocks, the composition of clasts, the euhedral character of many of the zircons, and the range in ages suggest that most were likely derived from Amisk Group and granitoid rocks in the western Flin Flon Domain. Rounded zircons are uncommon but provide evidence for the reworking of older Proterozoic sedimentary rocks, or a distant Archean or Early Proterozoic granitoid terrane.
7
Mitchelmore, Marlene Dredge, and Frederick A. Cook. "Inversion of the Proterozoic Wernecke basin during tectonic development of the Racklan Orogen, northwest Canada." Canadian Journal of Earth Sciences 31, no. 3 (March 1994): 447–57. http://dx.doi.org/10.1139/e94-041.
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New deep seismic reflection data coupled with regional stratigraphic correlations, drill-hole information, and potential field data are interpreted to provide images of Middle Proterozoic Wernecke Supergroup (meta-)sedimentary layers that were uplifted during tectonic development of the ca. 0.9–1.3 Ga Racklan Orogen in Canada's western Northwest Territories. The reflection data are located at the eastern front of the Mackenzie Mountains portion of the Canadian Cordillera and on the western flank of the Fort Simpson structural trend that is a prominent Proterozoic structure in the subsurface throughout the region. Along three parallel profiles, layers that are correlated with thick Wernecke Supergroup sedimentary rocks produce prominent reflections between about 3.0 and 9.0 s (about 7.5 and 23 km) that were arched prior to deposition of younger Proterozoic (probably Mackenzie Mountains Supergroup) and Phanerozoic sedimentary rocks. The strata are considered to be Wernecke basin sedimentary rocks that were uplifted during deformation associated with the development of the Racklan Orogen.
8
Sevigny, James H., Frederick A. Cook, and Elizabeth A. Clark. "Geochemical signature and seismic stratigraphic setting of Coppermine basalts drilled beneath the Anderson Plains in northwest Canada." Canadian Journal of Earth Sciences 28, no. 2 (February 1991): 184–94. http://dx.doi.org/10.1139/e91-018.
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Basalts drilled in the Petro-Canada – Canterra Tweed Lake M-47 well in the Anderson Plains of northwestern Canada have geochemical characteristics, including of major, trace, and rare earth elements, that are similar to those of the most enriched Coppermine lavas but significantly different from those of the younger Proterozoic volcanics, such as the Natkusiak basalts. This result provides a geological tie and timing constraint for structures observed on seismic reflection data in this area. Correlation of stratigraphic data from the well to seismic data shows that the lavas are within a sequence of layered reflections that onlap, and are thus younger than, easterly verging structures, and that were themselves probably uplifted prior to deposition of the Mackenzie Mountains Supergroup. These relationships thus show that at least two stages of Proterozoic compressional deformation, one that predated and one that postdated the basalts, produced structures beneath the Anderson Plains.
9
Jinbiao, Chen. "An explanatory note on proterozoic stratigraphic nomenclature used in the People's Republic of China." Precambrian Research 29, no. 1-3 (June 1985): 3–4. http://dx.doi.org/10.1016/0301-9268(85)90054-3.
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10
Nagovitsin, K. E., A. M. Stanevich, and T. A. Kornilova. "Stratigraphic setting and age of the complex Tappania-bearing Proterozoic fossil biota of Siberia." Russian Geology and Geophysics 51, no. 11 (November 2010): 1192–98. http://dx.doi.org/10.1016/j.rgg.2010.10.004.
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11
Patranabis Deb, Sarbani, and Asru K. Chaudhuri. "Stratigraphic architecture of the Proterozoic succession in the eastern Chattisgarth Basin, India: tectonic implications." Sedimentary Geology 147, no. 1-2 (March 2002): 105–25. http://dx.doi.org/10.1016/s0037-0738(01)00192-0.
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12
Sims, P. K., W. R. Van Schmus, K. J. Schulz, and Z. E. Peterman. "Tectono-stratigraphic evolution of the Early Proterozoic Wisconsin magmatic terranes of the Penokean Orogen." Canadian Journal of Earth Sciences 26, no. 10 (October 1989): 2145–58. http://dx.doi.org/10.1139/e89-180.
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The Early Proterozoic Penokean Orogen developed along the southern margin of the Archean Superior craton. The orogen consists of a northern deformed continental margin prism overlying an Archean basement and a southern assemblage of oceanic arcs, the Wisconsin magmatic terranes. The south-dipping Niagara fault (suture) zone separates the south-facing continental margin from the accreted arc terranes. The suture zone contains a dismembered ophiolite.The Wisconsin magmatic terranes consist of two terranes that are distinguished on the basis of lithology and structure. The northern Pembine–Wausau terrane contains a major succession of tholeiitic and calc-alkaline volcanic rocks deposited in the interval 1860–1889 Ma and a more restricted succession of calc-alkaline volcanic rocks deposited about 1835 – 1845 Ma. Granitoid rocks ranging in age from about 1870 to 1760 Ma intrude the volcanic rocks. The older succession was generated as island arcs and (or) closed back-arc basins above the south-dipping subduction zone (Niagara fault zone), whereas the younger one developed as island arcs above a north-dipping subduction zone, the Eau Pleine shear zone. The northward subduction followed deformation related to arc–continent collision at the Niagara suture at about 1860 Ma. The southern Marshfield terrane contains remnants of mafic to felsic volcanic rocks about 1860 Ma that were deposited on Archean gneiss basement, foliated tonalite to granite bodies ranging in age from about 1890 to 1870 Ma, and younger undated granite plutons. Following amalgamation of the two arc terranes along the Eau Pleine suture at about 1840 Ma, intraplate magmatism (1835 Ma) produced rhyolite and anorogenic alkali-feldspar granite that straddled the internal suture.
13
Syme, E. C., and A. H. Bailes. "Stratigraphic and tectonic setting of early Proterozoic volcanogenic massive sulfide deposits, Flin Flon, Manitoba." Economic Geology 88, no. 3 (May 1993): 566–89. http://dx.doi.org/10.2113/gsecongeo.88.3.566.
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14
Marian, Melinda L., and Robert H. Osborne. "Petrology, petrochemistry, and stromatolites of the Middle to Late Proterozoic Beck Spring Dolomite, eastern Mojave Desert, California." Canadian Journal of Earth Sciences 29, no. 12 (December 1992): 2595–609. http://dx.doi.org/10.1139/e92-206.
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The Beck Spring Dolomite is the medial unit of the Middle to Late Proterozoic Pahrump Group, the oldest sequence of sedimentary rocks in eastern California. Stratigraphic sections of the Beck Spring Dolomite examined in the eastern Mojave Desert and Death Valley regions consist of four members. These are, in ascending order, a lower cherty member, a lower laminated member, an oolitic–pisolitic member, and an upper cherty member. More than 80% of the Beck Spring Dolomite is algal-laminated dolomite with a possible Middle to Late Riphean stromatolite assemblage characterized by cf. Conophyton, eroded, irregular columnar forms similar to Kussiella or Baicalia, and several types of stratiform Stratifera. Petrographic, X-ray diffraction, and atomic absorption spectroscopic analyses indicate that the formation is composed of well-ordered replacement dolomite with less than 25% acid-insoluble residue. Concentrations of Fe and Mn are two to six times higher in the algal-laminated members than in the oolitic–pisolitic member, whereas the concentrations of Ca, Mg, Ba, Sr, Na, and K show no systematic variations. Stratigraphic relationships, primary and secondary sedimentary structures, petrology, and stromatolite assemblages suggest deposition during Middle to Late Proterozoic time on a platform that most likely included offshore shoals, restricted lagoons, and broad tidal flats with ponds, channels, and levees.
15
GEHLING, JAMES G., SÖREN JENSEN, MARY L. DROSER, PAUL M. MYROW, and GUY M. NARBONNE. "Burrowing below the basal Cambrian GSSP, Fortune Head, Newfoundland." Geological Magazine 138, no. 2 (March 2001): 213–18. http://dx.doi.org/10.1017/s001675680100509x.
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The range of Treptichnus pedum, the index trace fossil for the Treptichnus pedum Zone, extends some 4 m below the Global Standard Stratotype-section and Point for the base of the Cambrian Period at Fortune Head on the Burin Peninsula in southeastern Newfoundland. The identification of zigzag traces of Treptichnus isp., even further below the GSSP than T. pedum in the Fortune Head section, and in other terminal Proterozoic successions around the globe, supports the concept of a gradational onset of three-dimensional burrowing across the Proterozoic–Cambrian boundary. Although T. pedum remains a reasonable indicator for the base of the Cambrian Period, greater precision in the stratotype section can be achieved by a detailed re-evaluation of the stratigraphic ranges and the morphological variation of ichnotaxa included in the T. pedum Zone.
16
Myrow, P. M., N. C. Hughes, and N. R. McKenzie. "Reconstructing the Himalayan margin prior to collision with Asia: Proterozoic and lower Paleozoic geology and its implications for Cenozoic tectonics." Geological Society, London, Special Publications 483, no. 1 (November 2018): 39–64. http://dx.doi.org/10.1144/sp483.10.
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AbstractReconstructing the stratigraphic architecture of deposits prior to Cenozoic Himalayan uplift is critical for unravelling the structural, metamorphic, depositional and erosional history of the orogen. The nature and distribution of Proterozoic and lower Paleozoic strata have helped elucidate the relationship between lithotectonic zones, as well as the geometries of major bounding faults. Stratigraphic and geochronological work has revealed a uniform and widespread pattern of Paleoproterozoic strata >1.6 Ga that are unconformably overlain by <1.1 Ga rocks. The overlying Neoproterozoic strata record marine sedimentation, including a Cryogenian diamictite, a well-developed carbonate platform succession and condensed fossiliferous Precambrian–Cambrian boundary strata. Palaeontological study of Cambrian units permits correlation from the Indian craton through three Himalayan lithotectonic zones to a precision of within a few million years. Detailed sedimentological and stratigraphic analysis shows the differentiation of a proximal realm of relatively condensed, nearshore, evaporite-rich units to the south and a distal realm of thick, deltaic deposits to the north. Thus, Neoproterozoic and Cambrian strata blanketed the northern Indian craton with an extensive, northward-deepening, succession. Today, these rocks are absent from parts of the inner Lesser Himalaya, and the uplift and erosion of these proximal facies explains a marked change in global seawater isotopic chemistry at 16 Ma.
17
Carevic, Ivana, Miroljub Milincic, and Velimir Jovanovic. "Contribution to the study of geological setting of lower Aleksandrovac Zupa." Glasnik Srpskog geografskog drustva 89, no. 3 (2009): 135–46. http://dx.doi.org/10.2298/gsgd0903135c.
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Aleksandrovac Zupa represents the example of territorial area with composite geological structure and furthermore compound geotectonic framework. Due to the character of some formations, framework and time relation of deformation, these areas belong among the most compound on the Balkan Peninsula. On its territory, the big and composite structural-facies zones are being confronted and became imbued. In a stratigraphic point of view, the largest extend have the Miocene deposits that overlain the crystalline schists of Proterozoic. .
18
Birkenmajer, Krzysztof. "Polish Geological Research in Svalbard." Earth Sciences History 11, no. 2 (January 1992): 81–87. http://dx.doi.org/10.17704/eshi.11.2.n2747185001nv261.
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The Polish geological investigations started in the Svalbard archipelago in 1934. The most diversified stratigraphic, tectonic, sedimentological and palacontological work, along with detailed geological mapping, was carried out in the Hornsund area, south Spitsbergen, between 1957 and 1960, in connection with the Illrd International Geophysical Year and its prolongation (International Geophysical Co-operation). Between 1962 and 1970, some Polish geologists worked in Spitsbergen for the Norwegian Polar Institute. From 1974 onwards, the Polish geological investigations extended from southern to central and eastern Spitsbergen. In south Spitsbergen, at Hornsund, they are based at the Polish Scientific Station built already in 1957, and renovated in 1978. The paper presents a review of mainly pre-Quaternary (Proterozoic through Tertiary) geological, structuraltectonic, petrological, stratigraphic, palaeontologiesl and sedimentologtcal problems of Svalbard elaborated by the Polish geologists.
19
Clarke, G. L., J. P. Burg, and C. J. L. Wilson. "Stratigraphic and structural constraints on the proterozoic tectonic history of the Olary Block, South Australia." Precambrian Research 34, no. 2 (December 1986): 107–37. http://dx.doi.org/10.1016/0301-9268(86)90053-7.
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20
Bhattacharya, Purbasha, and Sarbani Patranabis-Deb. "Stratigraphic evolution of the Proterozoic succession in the western part of the Chattisgarh basin, India." Journal of the Geological Society of India 87, no. 3 (March 2016): 287–307. http://dx.doi.org/10.1007/s12594-016-0396-7.
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21
SAYLOR, BEVERLY Z., JANICE M. POLING, and WARREN D. HUFF. "Stratigraphic and chemical correlation of volcanic ash beds in the terminal Proterozoic Nama Group, Namibia." Geological Magazine 142, no. 5 (September 2005): 519–38. http://dx.doi.org/10.1017/s0016756805000932.
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At least twenty silicified volcanic ash beds have been identified in the Kuibis and Schwarzrand subgroups of the terminal Proterozoic Nama Group of Namibia. Nineteen of the Nama ash beds are in the Schwarzrand Subgroup in the Witputs subbasin. Two of these are in the siliciclastic-dominated lower part of the subgroup, which consists of the Nudaus Formation and Nasep Member of the Urusis Formation and comprises two depositional sequences. Identification and correlation of these ash beds are very well known based on stratigraphic position. Sixteen ash beds are contained within the carbonate-dominated strata of the Huns, Feldschuhhorn and Spitskop members of the Urusis Formation. These strata comprise four large-scale sequences and eighteen medium-scale sequences. Ash beds have been found in three of the large-scale sequences and seven of the medium-scale sequences. Correlations are proposed for these ash beds that extend over large changes in facies and stratal thickness and across transitions between the seaward margin, depocentre and landward margin of the Huns-Spitskop carbonate shelf. A study of whole rock and in situ phenocryst compositions was conducted to evaluate the feasibility of independently testing sequence stratigraphic correlations by geochemically identifying individual ash beds. Whole rock abundances of Al, Fe, Mg, K and Ti vary inversely with Si, reflecting variations in phenocryst concentration due to air fall and hydrodynamic sorting. These sorting processes did not substantially fractionate whole rock rare earth element abundances (REE), which vary more widely with Si. REE abundances are higher in samples of the Nudaus ash bed than in samples of the Nasep ash bed, independent of position in bed, phenocryst abundance, or grainsize, providing a geochemical means for discriminating between the two beds. Variations in the position of chondrite-normalized whole rock REE plots similarly support suspected correlations of ash beds between widely separated sections of the Spitskop Member. Abundances of Fe, Mg and Mn in apatite plot in distinct clusters for Spitskop ash beds that are known to be different and in clusters that overlap for ash beds suspected of correlating between sections. Abundances of REE in monazites differ for the Nudaus, Nasep and Spitskop ash beds in which these phenocrysts were identified. Multivariate statistical analysis provided a quantitative analysis of the discriminating power of different elements and found that whole rock abundances of Ge, Nb, Cs, Ba and La discriminate among the whole rock compositions of the Nudaus and Nasep ash beds and the Spitskop ash beds that are thought to correlate between sections. Each of the above geochemical signatures, by itself, is not definitive because the differences between beds are comparable to the variability within beds and because some signatures are shared by beds known to be different. Taken together, however, weight-of-evidence arguments based on multiple components and phases can successfully discriminate among Nama ash beds. Results from this study support sequence stratigraphic correlations of Spitskop ash beds that document stratal truncations and gaps in the record related to onlap and erosion.
22
Jackson, J., I. P. Sweet, and T. G. Powell. "STUDIES ON PETROLEUM GEOLOGY AND GEOCHEMISTRY, MIDDLE PROTEROZOIC, McARTHUR BASIN NORTHERN AUSTRALIA I: PETROLEUM POTENTIAL." APPEA Journal 28, no. 1 (1988): 283. http://dx.doi.org/10.1071/aj87022.
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Mature, rich, potential source beds and adjacent potential reservoir beds exist in the Middle Proterozoic sequence (1400-1800 Ma) of the McArthur Basin. The McArthur and Nathan Groups consist mainly of evaporitic and stromatolitic cherty dolostones interbedded with dolomitic siltstone and shale. They were deposited in interfingering marginal marine, lacustrine and fluvial environments. Lacustrine dolomitic siltstones form potential source beds, while potential reservoirs include vuggy brecciated carbonates associated with penecontemporaneous faulting and rare coarse-grained clastics. In contrast, the younger Roper Group consists of quartz arenite, siltstone and shale that occur in more uniform facies deposited in a stable marine setting. Both source and reservoir units are laterally extensive (over 200 km).Five potential source rocks at various stages of maturity have been discovered. Two of these source rocks, the lacustrine Barney Creek Formation in the McArthur Group and the marine Velkerri Formation in the Roper Group, compare favourably in thickness and potential with rich demonstrated source rocks in major oil-producing provinces. There is abundant evidence of migration of hydrocarbons at many stratigraphic levels. The geology and reservoir characteristics of the sediments in combination with the distribution of potential source beds, timing of hydrocarbon generation, evidence for migration and chances of preservation have been used to rank the prospectivity of the various stratigraphic units in different parts of the basin.
23
Gibson, Gail G. "Trace fossils from Late Precambrian Carolina slate belt, south-central North Carolina." Journal of Paleontology 63, no. 1 (January 1989): 1–10. http://dx.doi.org/10.1017/s0022336000040889.
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The volcanosedimentary sequence of the Carolina slate belt in south-central North Carolina was long thought to be unfossiliferous; however, the 5,484–7,315 meters of dominantly evenly bedded siltstones and mudstones have recently yielded body fossils of the late Precambrian Ediacarian fauna and a Middle Cambrian trilobite assemblage. Ongoing stratigraphic studies in the Carolina slate belt of southern North Carolina have now revealed trace fossils representing the ichnotaxa Gordia arcuata?, ?Helminthopsis sp., Monocraterion sp., Neonerites biserialis, N. uniserialis, ?Neonerites sp., Planolites beverlyensis, P. montanus, ?Planolites sp., Syringomorpha nilssoni?,? Tomaculum sp., Torrowangea sp., and three additional indeterminate ichnogenera. These trace fossils, lacking ornamentation and complex patterns, compare favorably with ichnofossil assemblages from Late Proterozoic stratigraphic sequences (Ichnofossil Zone I) elsewhere and support the late Precambrian age interpretation for the Carolina slate belt in south-central North Carolina.
24
Croon, Marcel, Joshua Bluett, Luke Titus, and Raymond Johnson. "Formation evaluation case study: Glyde unconventional Middle Proterozoic play in the McArthur Basin, northern Australia." APPEA Journal 55, no. 2 (2015): 429. http://dx.doi.org/10.1071/aj14064.
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The Glyde–1 and Glyde Sidetrack–1 wells were drilled by Armour Energy in the Glyde Sub-basin of the McArthur Basin, NT, Australia in August 2012. This program was to evaluate the unconventional hydrocarbon potential of the Barney Creek Shale source rock and the conventional potential of the Coxco Dolomite of the McArthur Group. The Glyde wells discovered gas in both formations. Transtensional faults in this region allowed to form a series of fault-bounded depocentres. The target gas source of the Glyde discovery is located in 1640 Ma organic-rich black shales of the Barney Creek Formation. Weatherford was contracted to acquire both vertical and lateral advanced log suites and perform subsequent log interpretation to constrain the in situ minimum and maximum horizontal stress regimes to assist with maximising gas production from future lateral placement pilot programs in the Coxco Hydrothermal Dolomite (HTD) Play. Two stratigraphic and structural domains were defined by the observed features in the image log data; a dolostone dominated, fractured strata below an erosional surface. Above this stratigraphic timeline is a monotonous package of laminated, lower-energy Barney Creek Formation sediments. Observed changes in azimuths and dips of the measured beddings suggest a phase of compression after deposition of the Barney Creek Formation, resulting in gentle folding of the formations. The porous gas-charged HTD play is drilled in top of the anticline, which is further characterised by a significant number of conductive fractures, likely indicative of open fractures.
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McDonough, Michael R., and Randall R. Parrish. "Proterozoic gneisses of the Malton Complex, near Valemount, British Columbia: U–Pb ages and Nd isotopic signatures." Canadian Journal of Earth Sciences 28, no. 8 (August 1991): 1202–16. http://dx.doi.org/10.1139/e91-108.
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Proterozoic gneisses of the Malton Complex in the vicinity of Valemount, British Columbia, occur in a series of lithologically and structurally complex, fault-bounded slices of crystalline basement and interleaved cover. Gneisses of the Malton Complex span the Southern Rocky Mountain Trench and underlie the western part of the Rocky Mountain fold and thrust belt and the eastern part of the Omineca Belt of the Canadian Cordillera. Structural and stratigraphic relationships indicate that they formed the basement upon which an enigmatic quartzite unit and the Late Proterozoic Windermere Supergroup were deposited.The Yellowjacket and Bulldog gneisses, on the east side of the Rocky Mountain Trench, have yielded four U–Pb zircon crystallization ages of ca. 1870 Ma, with εNd(T) values of −2.6 to −3.4. The Hugh Allan gneiss, also on the east side of the trench but separated from the Yellowjacket gneiss by a major thrust fault, includes leucocratic granite gneiss having a zircon U–Pb age of [Formula: see text], which has intruded an older (undated) lithologically heterogeneous assemblage of gneiss. The basal Windermere succession of the Valemount region is inferred to be younger than ca. 740 Ma, since these intrusions are not found within the Late Proterozoic stratified rocks.Augen granitoid orthogneiss of the Malton Range on the west side of the Rocky Mountain Trench has been dated as [Formula: see text] using zircons. A second sample yields data suggesting an age between 2050 and 2100 Ma, but its interpretation is uncertain because of scatter in analyses and possible zircon inheritance. The latter sample has an εNd(T) at 1990 Ma of −2.6. Nd model ages for the Malton, Yellowjacket, and Bulldog samples range from 2.45 to 2.56 Ga, indicating that the igneous protoliths were derived from a source that probably had some component of Archean crustal material involved.The U–Pb ages and Nd model ages are quite similar to those of rocks underlying portions of Alberta and the western Canadian Shield, specifically the Fort Simpson terrane, the Great Bear magmatic zone, and parts of the Thelon–Taltson arc. This evidence, as well as structural and stratigraphic arguments, links the Malton Complex gneisses with those of the Canadian Shield, precluding their derivation by large-magnitude displacements from the southwestern United States. Structural analysis indicates that they restore to locations 100–200 km southwest of their present exposure.Structural, stratigraphic, and isotopic data indicate that the Southern Rocky Mountain Trench is not a suture.
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Jansa, L. F., G. Pe-Piper, and B. D. Loncarevic. "Appalachian basement and its intrusion by Cretaceous dykes, offshore southeast Nova Scotia, Canada." Canadian Journal of Earth Sciences 30, no. 12 (December 1993): 2495–509. http://dx.doi.org/10.1139/e93-216.
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Aeromagnetic data collected between eastern Nova Scotia and southern Newfoundland provide new information about the offshore extension of the Avalon and Meguma terranes. A zone of short-wavelength anomalies that delineates Scatarie Ridge extends westward to the Late Proterozoic Fourchu Group in southeastern Cape Breton Island and eastward towards the Burin Peninsula of Newfoundland, suggesting that both regions belong to the same tectono-stratigraphic province of the Avalon composite terrane. A different zone of short-wavelength, discontinuously lineated anomalies at the northern edge of the Canso Ridge correlates with amphibolite-facies metamorphic rocks of the Meguma terrane on the Canso Peninsula, interpreted as an exhumed deeper metamorphic level of the Meguma terrane at its boundary with the Avalon terrane. The S-shaped pattern of long linear magnetic trends, characteristic of lower grade Meguma rocks on the southern flank of the Canso Ridge, indicates plastic deformation of the Meguma terrane during the Acadian orogeny when emplaced against the rigid Cape Breton Island block indentor. Analogous patterns occur off western Nova Scotia, suggesting little strike-slip motion occurred between the Meguma and Avalon terranes since the Acadian orogeny.Late Proterozoic rocks on Scatarie Ridge are intruded by Cretaceous diabase dykes. The diabase is alkaline with a within-plate geochemical signature, similar in composition to basalt flows in the Orpheus half-graben. A depleted-mantle model age TDM (Nd) of 731 Ma, εNd = +6.5, suggests that the magma was sourced from a lithospheric mantle reservoir involved in Late Proterozoic magmatic activity. Aeromagnetic data interpretation confirms the distribution of Cretaceous basalt flows and sills within Mesozoic sedimentary strata of the Orpheus half-graben previously outlined by seismic methods but was unable to differentiate between Proterozoic and Mesozoic intrusive rocks where the Proterozoic rocks lay near to the ocean floor.
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Cook, Frederick A., and Samantha M. Siegel. "From Proterozoic strata to a synthesized seismic reflection trace: implications for regional seismic reflection patterns in northwestern Canada." Canadian Journal of Earth Sciences 43, no. 11 (November 2006): 1639–51. http://dx.doi.org/10.1139/e06-040.
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Calculation of a synthetic seismic reflection trace from detailed descriptions of exposed Proterozoic strata in northwestern Canada permits correlation of reflections on regional seismic profiles to surface outcrop. Approximately 5.4 km (composite thickness) of Paleo- and Mesoproterozoic strata are exposed in the Muskwa anticlinorium that is located within the foreland of the Cordillera in northeastern British Columbia. The Tuchodi anticline is the easternmost structure of the Muskwa anticlinorium and has the deepest levels of Proterozoic strata exposed. At this location, prominent seismic reflection layering rises toward the surface and is easily correlated to the deeper formations of the Muskwa assemblage stratigraphy. These layers are followed westward into the middle crust, where they are overlain by dramatically thickened (by about five times) strata, primarily of the Tuchodi Formation. Along the same line of section, the Muskwa assemblage reflections overlie additional subparallel layered reflections at depth whose lithology and origin are unknown. However, coupled with other observations, including regional refraction results that indicate the crustal layers have both low seismic p-wave velocities and low ratios of p- and s-velocities, regional gravity observations that indicate the layers are low density, and correlation to similar layers on other seismic profiles that exhibit characteristic seismic stratigraphic features, the subparallel layers that are present beneath the known Muskwa assemblage are most easily interpreted as layered Proterozoic (meta-) sedimentary rocks. These results provide the basis for interpreting the Muskwa anticlinorium as a crustal-scale structure that formed when a deep basin of Proterozoic strata was inverted and thrust over an ~20 km high footwall ramp during Cordilleran orogenesis.
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Knoll, Andrew H. "The advent of the Phanerozoic world: Vendian stratigraphy, environmental change, and evolution." Paleontological Society Special Publications 6 (1992): 169. http://dx.doi.org/10.1017/s2475262200007292.
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The Vendian interval (ca. 610–540 Ma) links Proterozoic and Phanerozoic worlds of sharply contrasting character. Despite decades of study, the nature of this transition remains unclear, in part because of our limited ability to correlate Vendian successions or evaluate shifts in global environments. New data on secular variations in the C and Sr isotopic compositions of Vendian carbonates (and organic matter) provide an improved stratigraphic and biogeochemical framework for understanding latest Proterozoic biological and environmental evolution.Biologically, the Vendian interval is best known for the Ediacaran radiation of macroscopic animals, but this event is set within a broader Neoproterozoic diversification of higher eukaryotes. All three principal groups of multicellular algae radiated well before the beginning of the Vendian, as did a host of unicellular protists. In particular, successions deposited immediately after the Varanger Ice Age (ca. 610–590 Ma) are characterized by a high diversity of large and morphologically complex acritarchs; most of these forms disappeared after the first appearance of Ediacara-grade metazoans but before the eponymous fauna preserved in South Australia.Stratigraphic ordering of the earliest faunas is made possible by chemostratigraphy. Contrary to some published expectations, the morphologically complex petalonemids and skeletalized cloudinids of the lower Nama Group, Namibia, appear to predate, perhaps significantly, the classic faunas of South Australia, eastern Siberia, and elsewhere. Zircon ages for tuffs promise an absolute chronology for biological and biogeochemical events. The presence in pre-Cambrian rocks of Cloudina, calcareous algae and (?)siliceous discs comparable to chrysophyte scales demonstrates that eukaryotic calcite, aragonite, and silica biomineralization all predate the beginning of the Cambrian; however, sedimentological and petrographic features of carbonates and cherts suggest that skeletons first emerged as globally significant components of the carbon and silica cycles with the basal Cambrian radiation.Vendian evolution must also be evaluated within a broader context of environmental change. The Sr and C isotopic data that enhance stratigraphic correlation also record patterns of hydrothermal emission and organic carbon burial that must have affected pO2. Independent models by Derry and others and Knoll and Walker suggest that latest Proterozoic reductions in the hydrothermal flux of reduced materials into the oceans coupled with high burial rates of organic carbon resulted in a significant increase in global oxygen levels immediately prior to the great Ediacaran radiation.Many questions about Vendian evolution remain unresolved. Some will surely require fresh insights into the development and functional morphology of early metazoans, but it is becoming increasingly clear that a satisfactory accounting of Ediacaran animal diversification will not be achieved without a better understanding of the stratigraphic, environmental, and biological context in which it occurred.
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Devlin, William J. "Stratigraphy and sedimentology of the Hamill Group in the northern Selkirk Mountains, British Columbia: evidence for latest Proterozoic – Early Cambrian extensional tectonism." Canadian Journal of Earth Sciences 26, no. 3 (March 1989): 515–33. http://dx.doi.org/10.1139/e89-044.
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Three informal stratigraphic divisions are recognized in the uppermost Proterozoic – Lower Cambrian Hamill Group in the northern Selkirk Mountains of British Columbia. These informal divisions include a lower sandstone unit, a greenstone–graded-sandstone unit, and an upper sandstone unit. Both the lower and upper sandstone units display sedimentary characteristics that are uniform along strike and indicate a shallow-marine environment of deposition. As is typical of other exposures of the Hamil Group in southeastern British Columbia, the lower sandstone unit is coarser grained and more poorly sorted than the mature quartz arenites of the upper sandstone unit.The greenstone–graded-sandstone unit is a complex assemblage of mafic metavolcanic rocks and associated sandstone facies. This unit is highly variable along strike but essentially consists of a thick succession of subaqueous extrusive rocks overlain by a variety of sediment gravity-flow deposits. These latter deposits include resedimented conglomerates, debris-flow deposits, and trubidites (deposited from both high- and low-density turbidity currents). Stratigraphic sections of this unit are described in detail from three different localities and are examined in terms of their transport and depositional mechanisms.The stratigraphic succession of the Hamill Group indicates that deposition of the shallow-marine sands of the lower sandstone unit was abruptly interrupted by a period of volcanism, the creation of a paleoslope, and the deposition of a large volume of sediment gravity-flow deposits of the greenstone–graded-sandstone unit. These relations are attributed to an episode of syndepositional normal faulting. The inferred fault(s) could have served as the conduit for the extrusion of the volcanics. Offset along the fault(s), the tilting of fault blocks, and the consequent formation of an unstable slope adjacent to a fault scarp created an environment favorable for deposition of the sediment gravity flows. In general, deposition of proximal, base-of-slope deposits was followed by an aggradational basin-fill phase of sedimentation. With the waning of tectonic activity and the filling of the fault-bounded basin, depositon of shallow-marine sands resumed (the upper sandstone unit). The stratigraphic relations of the Hamill Group in the northern Selkirk Mountains are considered direct evidence for an episode of latest Proterozoic – Early Cambrian extensional tectonism. The evidence for an episode of rift-related tectonism in the northern Selkirk Mountains supports inferences concerning the timing of this event as derived from tectonic subsidence analyses of post-rift strata of the Cordilleran miogeocline.
30
Hofmann, H. J., and G. D. Jackson. "Shelf-facies microfossils from the Uluksan Group (Proterozoic Bylot Supergroup), Baffin Island, Canada." Journal of Paleontology 65, no. 03 (May 1991): 361–82. http://dx.doi.org/10.1017/s0022336000030353.
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Coccoid and filamentous microfossils in the Borden Rift Basin on northwestern Baffin Island and western Bylot Island are reported from 14 localities at six general stratigraphic levels in the Society Cliffs Formation, and one in the Victor Bay Formation. At least seven of 12 fossiliferous Society Cliffs samples, and one of two Victor Bay samples, are from cherty dolostones formed in shallow restricted, peritidal evaporitic environments. The remaining six fossiliferous samples accumulated in somewhat deeper, less restricted waters. The assemblage is preserved in black chert nodules and layers and comprises 30 taxa, including the filamentous formsArchaeotrichion? sp.,Tenuofilum septatum, Eomycetopsis robusta, Siphonophycus inornatum, S. kestron, Rhicnonema antiquum, Brachypleganonsp.,Eomicrocoleussp.,Uluksanella baffinensisn. gen. and sp.,Talakania? sp., the coccoid taxaEosynechococcus medius, E. grandis, Archaeoellipsoides obesus, Sphaerophycus parvum, S. medium, Myxococcoides minor, M. grandis, Melasmatosphaeraspp.,Phanerosphaerops capitaneus, Palaeoanacystissp.,Tetraphycus hebeiensis, Eogloeocapsa bella, Gloeodiniopsis magna, G.sp. 1,G. mikros, Polybessurus bipartitus, Cymatiosphaera? sp., the fusiformEupoikilofusa? sp., and rare specimens of two unidentified and problematic taxa.
31
Zhang, Yun, Leiming Yin, Shuhai Xiao, and Andrew H. Knoll. "Permineralized Fossils from the Terminal Proterozoic Doushantuo Formation, South China." Journal of Paleontology 72, S50 (July 1998): 1–52. http://dx.doi.org/10.1017/s0022336000059977.
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Permineralized fossils of the terminal Proterozoic (600–550 Ma) Doushantuo Formation, China, provide an unusually clear window on biological diversity just before the Ediacaran radiation. In the eastern Yangtze Gorges region, cherts in lower and upper Doushantuo carbonates preserve prokaryotes and protists from subtidal marine environments below and above fair weather wave base, respectively. Phosphorites in the Weng'an district to the south contain diverse acanthomorphic acritarchs as well as cellularly preserved thalloid algae. Twelve taxa of probable cyanobacteria are recognized. None is endemic to the Doushantuo Formation, and most have long stratigraphic ranges. The apparent restriction of two species to late Neoproterozoic and Cambrian rocks may reflect secular variation in taphonomic circumstance rather than evolution. Thirty-one species of spheromorphic and acanthomorphic acritarchs are recognized, about half of which occur elsewhere in rocks of the same approximate age. At least some of the eight formally described species of multicellular algae can be assigned with confidence to the Rhodophyta; these fossils provide a glimpse of structural and reproductive diversity in Neoproterozoic algae that is, to date, unique. Several reports of Doushantuo animal fossils have been published; most compelling are triact spicules identified in chert nodules. Along with more than two dozen taxa of compressed macrofossils preserved in carbonaceous shales from the top of the formation, Doushantuo permineralizations indicate that large animals radiated into a world rich in prokaryotic, protistan, and, even, multicellular diversity.
32
Mortimer, J. "Lithostratigraphy of the early Proterozoic Toumodi Volcanic Group in central côte d'ivoire: implications for Birrimian stratigraphic models." Journal of African Earth Sciences (and the Middle East) 14, no. 1 (January 1992): 81–91. http://dx.doi.org/10.1016/0899-5362(92)90057-j.
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33
Delpomdor, Franck R. A., Xavier Devleeschouwer, Simo Spassov, and Alain R. Préat. "Stratigraphic correlations in mid- to late-Proterozoic carbonates of the Democratic Republic of Congo using magnetic susceptibility." Sedimentary Geology 351 (April 2017): 80–101. http://dx.doi.org/10.1016/j.sedgeo.2017.02.007.
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34
Adams, E. W., S. Schroder, J. P. Grotzinger, and D. S. McCormick. "Digital Reconstruction and Stratigraphic Evolution of a Microbial-Dominated, Isolated Carbonate Platform (Terminal Proterozoic, Nama Group, Namibia)." Journal of Sedimentary Research 74, no. 4 (July 2004): 479–97. http://dx.doi.org/10.1306/122903740479.
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35
Abell, P. I., J. McClory, H. E. Hendry, and K. L. Wheatley. "Stratigraphic variations in carbon and oxygen isotopes in the dolostone of the Carswell Formation (Proterozoic) of northern Saskatchewan." Canadian Journal of Earth Sciences 26, no. 11 (November 1989): 2318–26. http://dx.doi.org/10.1139/e89-197.
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Petrographic and stable isotopic analyses of stromatolitic sediments deposited in nearshore environments provides us with some of the best information available on ancient environments. Diamond drill hole CAR 58 penetrated 110 m of sediments in the lowermost part of the Proterozoic (probably Helikian age) Carswell Formation of northern Saskatchewan and gave us such an opportunity. The rocks are mainly dolostone and include, in descending order of abundance, cyanobacterial laminites, stromatolites, dolomicrites, dolorudites, breccias, and oolites. Stromatolites and Cyanobacterial laminites increase in abundance up-section, and deposition is interpreted as having taken place in conditions of increasingly restricted water circulation through time. The carbon isotope ratios vary from about −0.5 to −1.5‰ (Pee Dee Belemnite (PDB)) in the section except near the base where they assume values near −2.5‰. The oxygen isotope ratios (vs. PDB) increase from about −9.3‰ at the base to −7‰ at the top, with anomolously high values, more positive than −7‰, at two positions in the sequence. Original depositional structures and textures are still visible in most of the rocks, but gypsum has been replaced by dolomite, there has been some silicification, and original features have been obliterated by dolomite rhombs in a few samples. The upward trend to less-negative values of the oxygen isotope ratios is interpreted in terms of changing depositional environment involving a deepening but more protected basin, with increased evaporational concentration of the heavier isotope. Scatter diagrams of carbon and oxygen isotope ratios place the Carswell Formation dolomites close to the mainstream of other Proterozoic stromatolites but indicating some evaporative alterations during deposition.
36
Green, J. W., A. H. Knoll, and K. Swett. "Microfossils from silicified stromatolitic carbonates of the Upper Proterozoic Limestone-Dolomite 'Series', central East Greenland." Geological Magazine 126, no. 5 (September 1989): 567–85. http://dx.doi.org/10.1017/s0016756800022858.
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AbstractSilicified flake conglomerates andin situstratiform stromatolites of the Upper Proterozoic (c.700–800 Ma) Limestone-Dolomite ‘Series’, central East Greenland, contain well preserved microfossils. Five stratigraphic horizons within the 1200 m succession contain microbial mat assemblages, providing a broad palaeontological representation of late Proterozoic peritidal mat communities. Comparison of assemblages demonstrates that the taxonomy and diversity of mat builder, dweller, and allochthonous populations all vary considerably within and among horizons. The primary mat builder in most assemblages isSiphonophycus inornatum, a sheath-forming prokaryote of probable but not unequivocally established cyanobacterial affinities. An unusual low diversity unit in Bed 17 is dominated by a different builder,Tenuofilum septatum, while a thin cryptalgal horizon in Bed 18 is built almost exclusively bySiphonophycus kestron.Although variable taphonomic histories contribute to observed assemblage variation, most differences within and among horizons appear to reflect the differential success or failure of individual microbial populations in colonizing different tidal flat microenvironments. Twenty-two taxa are recognized, of which two are described as new:Myxococcoides stragulescensn.sp. andScissilisphaera gradatan. sp.
37
Phillips, Bruce J., Alan W. James, and Graeme M. Philip. "THE GEOLOGY AND HYDROCARBON POTENTIAL OF THE NORTH-WESTERN OFFICER BASIN." APPEA Journal 25, no. 1 (1985): 52. http://dx.doi.org/10.1071/aj84004.
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Recent petroleum exploration in EP 186 and EP 187 in the north-western Officer Basin has greatly increased knowledge of the regional stratigraphy, structure and petroleum prospectivity of the region. This exploration programme has involved the drilling of two deep stratigraphic wells (Dragoon 1 and Hussar 1) and the acquisition of 1438 km of seismic data. Integration of regional gravity and aeromagnetic data with regional seismic and well data reveals that the Gibson Sub-basin primarily contains a Proterozoic evaporitic sequence. In contrast, the Herbert Sub-basin contains a Late Proterozoic to Cambrian clastic and carbonate sequence above the evaporites. This sequence, which was intersected in Hussar 1, is identified as the primary exploration target in the Western Officer Basin. The sequence contains excellent reservoir and seal rocks in association with mature source rocks. Major structuring of the basin has also been caused by compressive movements associated with the Alice Springs Orogeny. The northwestern Officer Basin thus has all of the ingredients for the discovery of commercial hydrocarbons.
38
Meyers, Stephen R., and Alberto Malinverno. "Proterozoic Milankovitch cycles and the history of the solar system." Proceedings of the National Academy of Sciences 115, no. 25 (June 2018): 6363–68. http://dx.doi.org/10.1073/pnas.1717689115.
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The geologic record of Milankovitch climate cycles provides a rich conceptual and temporal framework for evaluating Earth system evolution, bestowing a sharp lens through which to view our planet’s history. However, the utility of these cycles for constraining the early Earth system is hindered by seemingly insurmountable uncertainties in our knowledge of solar system behavior (including Earth–Moon history), and poor temporal control for validation of cycle periods (e.g., from radioisotopic dates). Here we address these problems using a Bayesian inversion approach to quantitatively link astronomical theory with geologic observation, allowing a reconstruction of Proterozoic astronomical cycles, fundamental frequencies of the solar system, the precession constant, and the underlying geologic timescale, directly from stratigraphic data. Application of the approach to 1.4-billion-year-old rhythmites indicates a precession constant of 85.79 ± 2.72 arcsec/year (2σ), an Earth–Moon distance of 340,900 ± 2,600 km (2σ), and length of day of 18.68 ± 0.25 hours (2σ), with dominant climatic precession cycles of ∼14 ky and eccentricity cycles of ∼131 ky. The results confirm reduced tidal dissipation in the Proterozoic. A complementary analysis of Eocene rhythmites (∼55 Ma) illustrates how the approach offers a means to map out ancient solar system behavior and Earth–Moon history using the geologic archive. The method also provides robust quantitative uncertainties on the eccentricity and climatic precession periods, and derived astronomical timescales. As a consequence, the temporal resolution of ancient Earth system processes is enhanced, and our knowledge of early solar system dynamics is greatly improved.
39
Sisodia, M. S. "Impact during the proterozoic era possibly inundated the earth with phosphorus." International Journal of Astrobiology 8, no. 3 (May 2009): 187–91. http://dx.doi.org/10.1017/s1473550409004480.
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AbstractThe stromatolites of the Precambrian Aravalli Supergroup outcropping around Udaipur, Rajasthan, India are classified into two distinct lithofacies: the older carbonate stromatolites facies and the younger phosphate-bearing stromatolite facies. Phosphate-bearing stromatolites of the same age have been reported from China, Russia and Australia. The phosphate-bearing stromatolites of Udaipur show fossil cyanobacteria. These cyanobacteria grew luxuriantly in the absence of any competitors and accumulated abnormal amounts of phosphorus from the novo phosphorus-rich environment, eventually forming a workable phosphate deposit owing to their post-mortem alteration. There is a sharp and abrupt contact between the two facies. This sharp contact or diastem underlying the phosphate-bearing stromatolites is of extreme importance as it denotes a stratigraphic hiatus characterizing a period of overall change in the environment. This change could be due to some catastrophic episode. The Earth during its geologic history has been subjected to several such episodes caused by certain high-energy events, such as impacts by extraterrestrial bodies. These impacts caused mass extinctions as occurred at the Permian–Triassic or Cretaceous–Tertiary boundary or the emergence of new flora and fauna as occurred at the Precambrian–Cambrian boundary. It is therefore argued that the diastem noted between carbonate and phosphate-bearing stromatolites is possibly due to an impact that inundated the Earth with phosphorus. Phosphorus is a key constituent of proteins, which are the major repository of chemical energy for metabolism. Its abundance after this event triggered the emergence of new advanced species.
40
Young, G. M., and V. A. Gostin. "Depositional environment and regional stratigraphic significance of the Serle Conglomerate: A Late Proterozoic submarine fan complex, South Australia." Palaeogeography, Palaeoclimatology, Palaeoecology 71, no. 3-4 (June 1989): 237–52. http://dx.doi.org/10.1016/0031-0182(89)90052-7.
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41
Young, Grant M. "Stratigraphic and tectonic settings of Proterozoic glaciogenic rocks and banded iron-formations: relevance to the snowball Earth debate." Journal of African Earth Sciences 35, no. 4 (November 2002): 451–66. http://dx.doi.org/10.1016/s0899-5362(02)00158-6.
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42
Kuznetsov, A. B., M. A. Semikhatov, and I. M. Gorokhov. "The Sr isotope chemostratigraphy as a tool for solving stratigraphic problems of the Upper Proterozoic (Riphean and Vendian)." Stratigraphy and Geological Correlation 22, no. 6 (November 2014): 553–75. http://dx.doi.org/10.1134/s0869593814060033.
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43
Kemnitz, Helga, Bodo-Carlo Ehling, Olaf Elicki, Hans-Joachim Franzke, Gerd Geyer, Ulf Linnemann, Dietmar Leonhardt, et al. "Proterozoikum–Silur in der Stratigraphischen Tabelle von Deutschland 2016 The Stratigraphic Table of Germany 2016: Proterozoic to Silurian." Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 168, no. 4 (March 2018): 423–46. http://dx.doi.org/10.1127/zdgg/2017/0134.
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44
Usenko, O. V. "Evolution of melts and fluids during the crust and mantle formation in Neo-Archean—Paleo-Proterozoic. Stratigraphic effects." Geofizicheskiy Zhurnal 38, no. 6 (February 2017): 40–63. http://dx.doi.org/10.24028/gzh.0203-3100.v38i6.2016.91961.
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45
GEYER, G. "The Fish River Subgroup in Namibia: stratigraphy, depositional environments and the Proterozoic–Cambrian boundary problem revisited." Geological Magazine 142, no. 5 (September 2005): 465–98. http://dx.doi.org/10.1017/s0016756805000956.
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The Fish River Subgroup of the Nama Group, southern Namibia, is restudied in terms of lithostratigraphy and depositional environment. The study is based on partly fine-scaled sections, particularly of the Nababis and Gross Aub Formation. The results are generally in accordance with earlier studies. However, braided river deposits appear to be less widely distributed in the studied area, and a considerable part of the formations of the middle and upper subgroup apparently were deposited under shallowest marine conditions including upper shore-face. Evidence comes partly from sedimentary features and facies distribution, and partly from trace fossils, particularly Skolithos and the characteristic Trichophycus pedum. Environmental conditions represented by layers with T. pedum suggest that the producer favoured shallow marine habitats and transgressive regimes. The successions represent two deepening-upward sequences, both starting as fluvial (braided river) systems and ending as shallow marine tidally dominated environments. The first sequence includes the traditional Stockdale, Breckhorn and lower Nababis formations (Zamnarib Member). The second sequence includes the upper Nababis (Haribes Member) and Gross Aub formations. As a result, the Nababis and Gross Aub formations require emendation: a new formation including the Haribes and Rosenhof and possibly also the Deurstamp members. In addition, four distinct sequence stratigraphic units are deter-minable for the Fish River Subgroup in the southern part of the basin. The Proterozoic–Cambrian transition in southern Namibia is most probably located as low as the middle Schwarzrand Subgroup. The environmentally controlled occurrence of Trichophycus pedum undermines the local stratigraphic significance of this trace fossil which is eponymous with the lowest Cambrian and Phanerozoic trace fossil assemblage on a global scale. However, occurrences of such trace fossils have to be regarded as positive evidence for Phanerozoic age regardless of co-occurring body fossils. Other suggestions strongly dispute the concept of the formal Proterozoic–Cambrian and Precambrian–Phanerozoic boundary. Carbon isotope excursions and radiometric datings for the Nama Group do not help to calibrate precisely the temporal extent of the Fish River Subgroup. Fossil content, sequence stratigraphy and inferred depositional developments suggest that this subgroup represents only a short period of late orogenic molasse sedimentation during the early sub-trilobitic Early Cambrian.
46
Jefferson, C. W., and R. R. Parrish. "Late Proterozoic stratigraphy, U–Pb zircon ages, and rift tectonics, Mackenzie Mountains, northwestern Canada." Canadian Journal of Earth Sciences 26, no. 9 (September 1989): 1784–801. http://dx.doi.org/10.1139/e89-151.
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Stratigraphic evidence suggests sporadic rifting began during deposition of the mainly platformal Mackenzie Mountains Supergroup: minor magnetite iron-formation in shale basins, lead–zinc in karsted and brecciated carbonates, red-bed and evaporite wedges, and basalts at the top. In the unconformably overlying Coates Lake Group similar climates and definite rifting are recorded by thin orthoconglomerates with thick red-bed and evaporite wedges containing stratiform copper deposits in paleovalleys. Unconformably above this, basal Windermere Supergroup records major climatic change and more emphatic rifting, with thick orthoconglomerates next to fault scarps overlain by glaciomarine deposits with volcanics and hydrothermal iron-formation.A quartz diorite plug, here dated by the U–Pb zircon method at [Formula: see text], is bounded by faults but is contained in a thrust panel together with Mackenzie Mountains Supergroup and is chemically similar to diabase sills previously dated at 766–769 ± 27 Ma (Rb–Sr). A diatreme intruding Coates Lake Group contains clasts of granite and gneiss from inferred basement. U–Pb systematics from a granite clast indicate inherited zircons about 1.6 ± 0.25 Ga in age and crystallization between 1100 and 1175 Ma, a maximum age for Mackenzie Mountains Supergroup.
47
Soper, N. J., and A. K. Higgins. "Basement–cover relationships in the East Greenland Caledonides: evidence from the Eleonore Bay Supergroup at Ardencaple Fjord." Transactions of the Royal Society of Edinburgh: Earth Sciences 84, no. 2 (1993): 103–15. http://dx.doi.org/10.1017/s0263593300003436.
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AbstractThe Eleonore Bay Supergroup (EBG) is a 16 km-thick shallow-water sequence of Neoproterozoic age that is preserved within the East Greenland Caledonides in several tracts, surrounded by crystalline gneisses and schistose supracrustal rocks. The apparent downward transition from non-metamorphic EBG into gneiss gave rise to the classic ‘stockwerke’ hypothesis, in which all the metamorphism was regarded as Caledonian, and differences in grade were ascribed to the ascent of a migmatite front to different levels within the orogen. Field and isotopic studies in the 1970s however revealed that the underlying gneisses and schists had undergone orogenic reworking in mid-Proterozoic time; the EBG–basement contact was then interpreted as an approximately bedding-parallel décollement with apparent lag geometry, that is with EBG cover rocks in its hangingwall.Recent work in the northernmost EBG tract, at Ardencaple Fjord, has shed light on the problems posed by the basal relationships of the EBG, and together with regional structural and stratigraphic data leads to the following interpretation. There are two regionally important basement-cover interfaces within the East Greenland Caledonides. The earlier one is between Archaean/early Proterozoic gneisses and early Proterozoic supracrustal rocks, which were pervasively deformed in mid-Proterozoic time and form the basement to the Neoproterozoic Eleonore Bay cover sequence. This was deposited on a vast, continually subsiding shelf that is now preserved in East and NE Greenland and Svalbard, and contains Grenville detritus. EBG deposition was terminated by major extensional faulting of Vendian age; the succeeding Tillite Group is interpreted as a syn-rift sequence, presumably associated with the opening of Iapetus.The EBG–basement contacts that are not late faults are inferred to be extensional shear zones of Vendian age. These were reactivated in compression during the Caledonian orogeny in the Silurian, with metamorphic and fabric convergence, which accounts for the apparent downward transition from sedimentary rocks through schists into gneisses. Caledonian shortening was not large; inversion of the Vendian grabens was incomplete, so that the marginal shear zones retained their lag geometry and large tracts of low grade Eleonore Bay sediments are preserved at the present erosion level, surrounded by Proterozoic basement rocks, within the Caledonian belt of East Greenland.
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Seilacher, Adolf, and Friedrich Pflüger. "Trace fossils from the Late Proterozoic of North Carolina: early conquest of deep-sea bottoms." Paleontological Society Special Publications 6 (1992): 265. http://dx.doi.org/10.1017/s247526220000825x.
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The trace fossil Oldhamia reflects systematic strip mining of an infaunal, worm-like sediment feeder. It is known from many parts of the world in Cambrian complexes, whose flysch-like and accreted character suggests deposition on a deep continental slope. In similar rocks of the North Carolina Slate Belt. Oldhamia is associated with rare specimens of the Ediacara-type body fossil Pteridinium, as well as tool marks of a problematic stiff organism reminiscent of graptolite stipes (Vendospica).This occurrence (1) extends the stratigraphic range of Oldhamia into the Late Proterozoic. It also reminds us that, by that time, worm-like, endobenthic bilaterians (2) had become behaviorally specialized and (3) had colonized shelf and deep-sea bottoms well before the Cambrian evolutionary explosion. (4) Since bioturbators were small and did burrow strictly along bedding planes, their mixing effect was as yet negligible. (5) The new tool-mark fossils tell us that complex, organic-walled and perhaps colonial organisms were around in addition to sand-corals (Psammocorallia), possibly sponges and the probably plasmodial Vendobionta.
49
Sevigny, James H., and Philip S. Simony. "Geometric relationship between the Scrip Nappe and metamorphic isograds in the northern Adams River area, Monashee Mountains, British Columbia." Canadian Journal of Earth Sciences 26, no. 3 (March 1989): 606–10. http://dx.doi.org/10.1139/e89-051.
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In the northern Adams River area of the Monashee Mountains, British Columbia, the axial trace of the Scrip Nappe, a megascopic southwest-verging recumbent F1 anticline, can be traced upward through all stratigraphic units of the Late Proterozoic Horsethief Creek Group westward to where it is truncated by the Eocene North Thompson Fault. The Scrip Nappe has been coaxially folded by a northeast-verging, isoclinal F2 synform with a southwest-dipping axial surface and an amplitude of about 6 km. A metamorphic culmination, defined by the surface trace of the muscovite-out isograd and consisting of a series of northwest–southeast-striking isogradic antiforms and synforms, postdates Early Cretaceous F2 folding and predates Eocene normal faulting at 51–45 Ma.
50
Suchy, Daniel R., and Colin W. Stearn. "Evidence of a continent-wide fault system on the Attawapiskat River, Hudson Bay Platform, northern Ontario." Canadian Journal of Earth Sciences 30, no. 8 (August 1993): 1668–73. http://dx.doi.org/10.1139/e93-145.
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The grouping of areas of outcrop of Lower Silurian reefs along a stretch of the Attawapiskat River west of James Bay (northern Ontario, Canada) is controlled by a conjugate set of faults striking approximately 60 and 280°. The faults are evident in disturbed outcrops along the river and in subtle lineaments revealed in aerial photographs and Landsat imagery in the surrounding marshland topography. Slumping of large blocks from a reef crest in Silurian time and stratigraphic relationships within the Hudson Basin indicate a major episode of movement in late Llandovery time. Movements on the fault set have been traced back to Proterozoic time and, to affect the present subdued topography recently emerged from marine inundation, must have been renewed in rapid recent postglacial uplift of this area.

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