Marine flooding surfaces recorded in Permian black shales and coal deposits of the Main Karoo Basin (South Africa): Implications for basin dynamics and cross-basin correlation

Götz, Annette E.; Ruckwied, Katrin; Wheeler, Alexander

doi:10.1016/j.coal.2017.10.014

Cited by 22 publications

(7 citation statements)

References 77 publications

(131 reference statements)

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“…These formations were previously interpreted as deposited in a relatively sediment‐starved, basin‐floor environment (Visser, , ; Viljoen, ), although water palaeodepth has not been defined due to the absence of diagnostic microfossils. Some authors have suggested a northern source for the Prince Albert, Whitehill and Collingham formations, based on facies distribution and sparse palaeocurrent indicators (Chukwuma & Bordy, ) and palynology (Götz et al ., ). Ash beds potentially derived from the Choiyoi volcanic province (Northern Patagonia) are interbedded in these formations, with a higher density in the Collingham Formation (McLachlan & Jonker, ; Veevers et al ., ; Viljoen, ; McKay et al ., ).…”

Section: Geological Settingmentioning

confidence: 97%

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Transport and deposition of mud in deep‐water environments: Processes and stratigraphic implications

et al. 2019

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Deep-water mudstones are often considered as background sediments, deposited by vertical suspension fallout, and the range of transport and depositional processes are poorly understood compared with their shallowmarine counterparts. This study presents a dataset from a 538Á50 m thick cored succession through the Permian muddy lower Ecca Group of the Tanqua depocentre (south-west Karoo Basin, South Africa). This study aims to characterize the range of mudstone facies, transport and depositional processes, and stacking patterns recorded in deep-water environments prior to deposition of the Tanqua Karoo sandy basin-floor fans. A combination of macroscopic and microscopic description techniques and ichnological analysis has defined nine sedimentary facies that stack in a repeated pattern to produce 2 to 26 m thick depositional units. The lower part of each unit is characterized by bedded mudstone deposited by dilute, low-density turbidity currents with evidence for hyperpycnal-flow processes and sediment remobilization. The upper part of each unit is dominated by more organic-rich bedded mudstone with common mudstone intraclasts, deposited by debris flows and transitional flows, with scarce indicators of suspension fallout. The intensity of bioturbation and burrow size increases upward through each depositional unit, consistent with a decrease in physicochemically stressed conditions, linked to a lower sediment accumulation rate. This vertical facies transition in the single well dataset can be interpreted to represent relative sea-level variations; the hyperpycnal stressed conditions in the lower part of the units were driven by relative sea-level fall, and the more bioturbated upper part of the units represent backstepping, related to relative sea-level rise. Alternatively, this facies transition may represent autogenic compensational stacking. The prevalence of sediment density flow deposits, even in positions distal or lateral to the sediment entry point, challenges the idea that deep-water mudstones are primarily the deposits of passive rainout along continental margins.

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Section: Geological Settingmentioning

confidence: 97%

“…Some authors have proposed that the Ecca Group was deposited in an open marine basin with normal salinity, based on the presence of marine fossils (McLachlan & Anderson, ; Visser, ; Götz et al ., ). Fully marine conditions are also suggested by a Rb/K palaeosalinity proxy (Scheffler et al ., ; Geel et al ., ).…”

Section: Geological Settingmentioning

confidence: 97%

Transport and deposition of mud in deep‐water environments: Processes and stratigraphic implications

et al. 2019

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“…Ongoing studies thus aim to establish an integrated stratigraphic framework of the Karoo sequence of the Moatize sub-basin, including climatic signatures to further develop intra-Gondwanan correlation schemes. Province this study), and the northern and southern Main Karoo Basin Götz, 2015;Götz et al, 2018). Radiometric dates from…”

Section: Discussionmentioning

confidence: 74%

Southwestern Gondwana’s Permian climate amelioration recorded in coal-bearing deposits of the Moatize sub-basin (Mozambique)

2020

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The postglacial climate history of Gondwana represents the most prominent climate amelioration in the Phanerozoic, ranging from severe icehouse conditions in the Late Carboniferous (Pennsylvanian) to extreme hothouse conditions in the Early Triassic.Here we report new sedimentological and palynological data from a 350 m thick coalbearing succession intersected by borehole 945L_0022, drilled in the eastern Tete Province of Mozambique, which documents southwestern Gondwana's Permian postglacial climate amelioration. Palynofacies data further support the environmental reconstructions interpreted from the sedimentary succession. Changes in the palynomorph assemblage document a shift from cold, to cool-temperate, to warmtemperate climatic conditions. This climate signature corresponds with observations from other depositional environments elsewhere in southern Africa, and thus enables correlation on a regional to interregional scale. Thick lacustrine deposits are described within the lower coal-bearing succession, reflecting the final glacial retreat, with melt waters supplying fresh water to the incipient lacustrine system. Lakes as characteristic postglacial sedimentary sinks are excellent palaeoclimate archives and the high Total Organic Carbon content of these fine-grained clastic sediments also makes them potential source rock targets for oil and gas.

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“…East of the city of Johannesburg, the Witbank coal field also constitutes a pre-Karoo glacial irregular topography. In this region, coal seams of the postglacial Vryheid Formation (Ecca Group) either rest conformably on glaciogenic deposits of the Dwyka Group and fill local hollows and depressions, 10-60 m deep, of the paleotopography inherited from glacial erosion, or directly lies on the bedrock on paleohighs (Le Blanc Smith and Eriksson, 1979;Le Blanc Smith, 1980;Cairncross and Cadle, 1988;Holland et al, 1989;Götz et al, 2018). The mining of coal seams rejuvenates the pre-Karoo topography.…”

Section: The Cargonian Highlandmentioning

confidence: 99%

The Glacial Paleolandscapes of Southern Africa: the Legacy of the Late Paleozoic Ice Age

Dietrich,

Guillocheau,

Douillet

et al. 2024

Preprint

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Abstract. The modern relief of Southern Africa is characterised by stepped plateaus bordered by escarpments. This morphology is thought to result from stepwise uplift and ensuing continental-scale erosion of the region as it rode over Africa’s mantle ‘superplume’ following the break-up of Gondwana, i.e. since the mid-Mesozoic. We demonstrate in this contribution that this modern morphology of Southern Africa is in fact largely inherited from glacial erosion associated to the Late Paleozoic Ice Age (LPIA) that occurred between 370 and 260 Myr ago, during which Gondwana – which included Southern Africa – was covered in thick ice masses. Southern Africa hosts vast (up to 106 km²) and thick (up to 5 km) sedimentary basins ranging from the Carboniferous, represented by glaciogenic sediments tied to the LPIA, to the Jurassic-Cretaceous. These basins are separated by intervening regions largely underlain by Archean to Paleoproterozoic cratonic areas that correspond to paleohighlands that preserve much of the morphology that existed when sedimentary basins formed, and particularly glacial landforms. In this contribution, we review published field and remote data and provide new large-scale interpretation of the geomorphology of these paleohighlands of Southern Africa. Our foremost finding is that over Southern Africa, vast surfaces, tens to hundreds of thousands km² (71.000–360.000 km²) are exhumed glacial landscapes tied to the LPIA. These glacial landscapes manifest in the form of cm-scale striated pavements, m-scale fields of roches moutonnées, whalebacks and crag-and-tails, narrow gorges cut into high-standing mountain ranges, and km-scale planation surfaces and large U-shaped valleys, overdeepenings, fjords and troughs up to 200 km in length. Many modern savannahs and desertic landscapes of Southern Africa are therefore relict glacial landscapes and relief ca. 300 Myr old. These exhumed glacial relief moreover exerts a strong control on the modern-day aspect of the geomorphology of Southern Africa as (1) some escarpments that delineate high-standing plateaux from valleys and coastal plains are inherited glacial relief in which glacial valleys are carved, (2) some hill or mountain ranges already existed by LPIA times and were likely modelled by glacial erosion, and (3) the drainage network of many of the main rivers of Southern Africa is funnelled through ancient glacial valleys. This remarkable preservation allowed us to reconstruct the paleogeography of Southern Africa in the aftermath of the LPIA, consisting of highlands over which ice masses nucleated and from which they flowed through the escarpments and toward lowlands that now correspond to sedimentary basins. Our findings therefore indicate that glacial landforms and relief of continental-scale can survive over tens to hundreds of million years. This preservation and modern exposure of the glacial paleolandscapes were achieved through burial under piles of Karoo sediments and lavas over ca. 120 to 170 million years and a subsequent exhumation since the middle Mesozoic owing to the uplift of Southern Africa. Owing to strong erodibility contrasts between resistant Precambrian bedrock and softer sedimentary infill, the glacial landscapes have been exhumed and rejuvenated. We therefore emphasise the need of considering the legacy of glacial erosion processes and the resulting presence of glacial landscapes when assessing the post-Gondwana-breakup evolution of Southern African topography and its resulting modern-day aspect, as well as inferences about climate changes and tectonic processes. Finally, we explore the potential pre-LPIA origin for some of the landscapes. In the Kaoko region of northern Namibia, the escarpments into which glacial valleys are carved may correspond to a reminiscence of the Kaoko Pan-African Belt, whose crustal structures were either reactivated or where relief persisted since then. In South Africa, the escarpment bordering the paleohighland corresponds to crustal-scale faults that might have been reactivated during LPIA by subsidence processes. These inherited morphological or crustal features may have been re-exploited and enhanced by glacial erosion during the LPIA, as it is the case for some Quaternary glacial morphology.

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Marine flooding surfaces recorded in Permian black shales and coal deposits of the Main Karoo Basin (South Africa): Implications for basin dynamics and cross-basin correlation

Cited by 22 publications

References 77 publications

Transport and deposition of mud in deep‐water environments: Processes and stratigraphic implications

Transport and deposition of mud in deep‐water environments: Processes and stratigraphic implications

Southwestern Gondwana’s Permian climate amelioration recorded in coal-bearing deposits of the Moatize sub-basin (Mozambique)

The Glacial Paleolandscapes of Southern Africa: the Legacy of the Late Paleozoic Ice Age

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