Bibliografías temáticas / Geology, Stratigraphic – South Africa – Karoo

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Literatura académica sobre el tema "Geology, Stratigraphic – South Africa – Karoo"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 17 de febrero de 2022

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Artículos de revistas sobre el tema "Geology, Stratigraphic – South Africa – Karoo"

Bordy, E. M., S. Spelman, D. I. Cole, and P. Mthembi. "Lithostratigraphy of the Pietermaritzburg Formation (Ecca Group, Karoo Supergroup), South Africa." South African Journal of Geology 120, no. 2 (2017): 293–302. http://dx.doi.org/10.25131/gssajg.120.2.293.

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Abstract The Lower Permian Pietermaritzburg Formation is a mudrock-dominated, upward-coarsening stratigraphic unit in the lower Ecca Group (Karoo Supergroup) in the northeastern part of the main Karoo Basin of South Africa. The formation extends over most of the KwaZulu-Natal Province, and due to its lithology and the local climate, it is usually poorly exposed; hence the description is mainly based on borehole records. From a measured thickness of about 430 m south of the type area around Pietermaritzburg, the formation thins progressively northwards and pinches out against the Dwyka Group and pre-Karoo basement north of latitude 26° 30' S. This Lower Permian formation is considered a stratigraphic equivalent of the Prince Albert Formation in the southern part of the main Karoo Basin. The Pietermaritzburg Formation only preserves scattered, fragmentary plant fossil and invertebrate trace fossils, which are diagnostic of marine conditions (e.g. Helminthopsis). Based on its sedimentary facies characteristics and ichnofossil assemblages, the unit was probably deposited under low energy conditions on a northerly shallowing marine shelf that initially experienced deepening (during a major Artinskian transgression) and then shallowing in the early Kungurian.

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Griffis, Neil Patrick, Isabel Patricia Montañez, Roland Mundil, et al. "Coupled stratigraphic and U-Pb zircon age constraints on the late Paleozoic icehouse-to-greenhouse turnover in south-central Gondwana." Geology 47, no. 12 (2019): 1146–50. http://dx.doi.org/10.1130/g46740.1.

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Abstract The demise of the Late Paleozoic Ice Age has been hypothesized as diachronous, occurring first in western South America and progressing eastward across Africa and culminating in Australia over an ∼60 m.y. period, suggesting tectonic forcing mechanisms that operate on time scales of 106 yr or longer. We test this diachronous deglaciation hypothesis for southwestern and south-central Gondwana with new single crystal U-Pb zircon chemical abrasion thermal ionizing mass spectrometry (CA-TIMS) ages from volcaniclastic deposits in the Paraná (Brazil) and Karoo (South Africa) Basins that span the terminal deglaciation through the early postglacial period. Intrabasinal stratigraphic correlations permitted by the new high-resolution radioisotope ages indicate that deglaciation across the S to SE Paraná Basin was synchronous, with glaciation constrained to the Carboniferous. Cross-basin correlation reveals two additional glacial-deglacial cycles in the Karoo Basin after the terminal deglaciation in the Paraná Basin. South African glaciations were penecontemporaneous (within U-Pb age uncertainties) with third-order sequence boundaries (i.e., inferred base-level falls) in the Paraná Basin. Synchroneity between early Permian glacial-deglacial events in southwestern to south-central Gondwana and pCO2 fluctuations suggest a primary CO2 control on ice thresholds. The occurrence of renewed glaciation in the Karoo Basin, after terminal deglaciation in the Paraná Basin, reflects the secondary influences of regional paleogeography, topography, and moisture sources.

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de V. Wickens, H., and D. I. Cole. "Lithostratigraphy of the Kookfontein Formation (Ecca Group, Karoo Supergroup), South Africa." South African Journal of Geology 120, no. 3 (2017): 447–58. http://dx.doi.org/10.25131/gssajg.120.3.447.

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Abstract The Permian Kookfontein Formation forms part of the upper Ecca Group in the southwestern part of the main Karoo Basin of South Africa. It occupies a stratigraphic position between the underlying Skoorsteenberg Formation and the overlying Waterford Formation, with its regional extent limited to the cut-off boundaries of the Skoorsteenberg Formation. The Kookfontein Formation has an average thickness of 200 m, coarsens upwards, and predominantly comprises dark grey shale, siltstone and thin- to thick-bedded, fine- to very fine-grained, feldspathic litharenite. Characteristic upward-coarsening and thickening successions and syn-sedimentary deformation features reflect rapid deposition and progradation of a predominantly fluvially-dominated prodelta and delta front slope environment. The upward increase in the abundance of wave–ripple marks further indicates a gradual shallowing of the depositional environment through time. The upper contact with the Waterford Formation is gradational, which indicates a transition from deposition in an unstable upper slope/shelf margin environment to a more stable shelf setting.

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Viglietti, P. A. "Biostratigraphy of the Daptocephalus Assemblage Zone (Beaufort Group, Karoo Supergroup), South Africa." South African Journal of Geology 123, no. 2 (2020): 191–206. http://dx.doi.org/10.25131/sajg.123.0014.

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Abstract The name Daptocephalus Assemblage Zone (DaAZ) is re-instated for vertebrate assemblages of the uppermost Permian strata (Balfour, upper Teekloof, and Normandien formations) of South Africa’s main Karoo Basin (MKB). This involved taxonomic revision of the dicynodontoid “Dicynodon” sensu lato, reviving Daptocephalus leoniceps, and revising the stratigraphic ranges of co-occurring index taxa (Theriognathus microps, Procynosuchus delaharpeae) of the Dicynodon Assemblage Zone (DiAZ) as it was known. This work has demonstrated the appearance of index taxa below the stratigraphically defined DiAZ. Moreover, the first appearance of Lystrosaurus maccaigi and Moschorhinus kitchingi in the upper reaches of the biozone calls for the establishment of a two-fold subdivision of the current DaAZ into lower (Dicynodon-Theriognathus) and upper (Lystrosaurus maccaigi-Moschorhinus) subzones. The biostratigraphic utility of Daptocephalus and other South African dicynodontoids outside of the MKB is limited due to basinal endemism at the species level and varying temporal ranges of dicynodontoids globally. Accordingly, their use is recommended only for correlation within the Karoo Basin at this stage.

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van der Werff, W., and S. Johnson. "High resolution stratigraphic analysis of a turbidite system, Tanqua Karoo Basin, South Africa." Marine and Petroleum Geology 20, no. 1 (2003): 45–69. http://dx.doi.org/10.1016/s0264-8172(03)00025-4.

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Viglietti, P. A., B. W. McPhee, E. M. Bordy, et al. "Biostratigraphy of the Massospondylus Assemblage Zone (Stormberg Group, Karoo Supergroup), South Africa." South African Journal of Geology 123, no. 2 (2020): 249–62. http://dx.doi.org/10.25131/sajg.123.0018.

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Abstract The Massospondylus Assemblage Zone is the youngest tetrapod biozone in the Karoo Basin (upper Stormberg Group, Karoo Supergroup) and records one of the oldest dinosaur dominated ecosystems in southern Gondwana. Recent qualitative and quantitative investigations into the biostratigraphy of the lower and upper Elliot formations (lEF, uEF) and Clarens Formation in the main Karoo Basin resulted in the ﬁrst biostratigraphic review of this stratigraphic interval in nearly four decades, allowing us to introduce a new biostratigraphic scheme, the Massospondylus Assemblage Zone (MAZ). The MAZ expands upon the Massospondylus Range Zone by including the crocodylomorph Protosuchus haughtoni and the ornithischian Lesothosaurus diagnosticus as two co-occurring index taxa alongside the main index taxon, the sauropodomorph Massospondylus carinatus. With a maximum thickness of ~320 m in the southeastern portion of the basin, our new biozone is contained within the uEF and Clarens formations (upper Stormberg Group), however, based on vertebrate ichnofossils evidence, it may potentially extend into the sedimentary units of the lowermost Drakensberg Group. We do not propose any further subdivisions, and do not consider the Tritylodon Acme Zone (TAZ) as a temporal biostratigraphic marker within the MAZ. The MAZ is currently accepted to range in age between the Hettangian and Pliensbachian, however a faunal turnover, which observes an increase in the diversity of dinosaur clades, crocodylomorph, and mammaliaform taxa in the lower uEF, could reﬂect effects of the end-Triassic extinction event (ETE).

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Wild, R., S. S. Flint, and D. M. Hodgson. "Stratigraphic evolution of the upper slope and shelf edge in the Karoo Basin, South Africa." Basin Research 21, no. 5 (2009): 502–27. http://dx.doi.org/10.1111/j.1365-2117.2009.00409.x.

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Gastaldo, Robert A., Kaci Kus, Neil Tabor, and Johann Neveling. "Calcic Vertisols in the upper Daptocephalus Assemblage Zone, Balfour Formation, Karoo Basin, South Africa: Implications for Late Permian Climate." Journal of Sedimentary Research 90, no. 6 (2020): 609–28. http://dx.doi.org/10.2110/jsr.2020.32.

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ABSTRACT The fully continental succession of the Beaufort Group, Karoo Basin, South Africa, has been used in the development of environmental models proposed for the interval that spans the contact between the Daptocephalus to Lystrosaurus Assemblage Zones, associated by some workers with the end-Permian extinction event. An aridification trend is widely accepted, yet geochemical data indicate that the majority of in situ paleosols encountered in this interval developed in waterlogged environments. To date, the presence of calcic paleosols in the latest Permian can be inferred only from the presence of calcite-cemented pedogenic nodules concentrated in fluvial channel-lag deposits. Here, we report on the first empirical evidence of in situ calcic Vertisols found in the upper Daptocephalus Assemblage Zone near Old Wapadsberg Pass, one of eight classic localities in which the vertebrate turnover is reported in the Karoo Basin. Seven discrete intervals of calcic Vertisols, exposed over a very limited lateral extent, occur in an ∼ 25 m stratigraphic interval. Estimates of mean annual temperature and mean annual precipitation are calculated from geochemical measurements of one paleosol, and these estimates indicate that the prevailing climate at the time of pedogenesis was seasonally cold and humid. Correlation with adjacent stratigraphic sections indicates that the late Permian landscape experienced poorly drained and better-drained phases, interpreted to reflect a climate that varied between episodically dry and episodically wet. In contrast to a paleoenvironmental reconstruction of unidirectional aridification from strata in the Wapadsberg Pass region, this study provides new evidence for a wetting trend towards the Daptocephalus–Lystrosaurus Assemblage-Zone boundary.

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Sixsmith, P. J., S. S. Flint, H. DeV Wickens, and S. D. Johnson. "Anatomy and Stratigraphic Development of a Basin Floor Turbidite System in the Laingsburg Formation, Main Karoo Basin, South Africa." Journal of Sedimentary Research 74, no. 2 (2004): 239–54. http://dx.doi.org/10.1306/082903740239.

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Tankard, Anthony, Herman Welsink, Peter Aukes, Robert Newton, and Edgar Stettler. "Tectonic evolution of the Cape and Karoo basins of South Africa." Marine and Petroleum Geology 26, no. 8 (2009): 1379–412. http://dx.doi.org/10.1016/j.marpetgeo.2009.01.022.

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