The Late Palaeozoic Ice Age unconformity in southern Namibia viewed as a patchwork mosaic

Heron, Daniel Paul Le; Kettler, Christoph; Griffis, Neil; Dietrich, Pierre; Montañez, Isabel P.; Osleger, David A.; Hofmann, Axel; Douillet, Guilhem Amin; Mundil, Roland

doi:10.1002/dep2.163

Cited by 8 publications

(6 citation statements)

References 45 publications

(82 reference statements)

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“…Namibia hosts one of the highest fidelity records of the late Paleozoic glaciation, preserving ancient fjord networks, a complex basal unconformity that extends for 100's of kms in outcrop and large linear erosional features including drumlins, which attest to the subglacial history of this region (Figs 2 and 3B;Martin 1981;Dietrich et al, 2019;Andrews et al, 2019;le Heron et al, 2021). During the acme of the LPIA a large, at least 1.7 km thick, ice sheet covered northern Namibia (Dietrich et al, 2021).…”

Section: Kalahari Basinmentioning

confidence: 99%

“…Ultimately, these valleys were filled with marine rocks and given the scale and well-preserved nature of the deposits are regarded as one of the world's best-preserved examples of a pre-Cenozoic fjord network (Dietrich et al, 2021;Le Heron et al, 2022). In southern Namibia, equally impressive outcrops within the Aranos and Karasburg subbasins of the greater Kalahari, record a complex system of fluvial incision, subglacial erosion, and ice proximal deposits, which overlie unconformably Precambrian-Cambrian basement attesting to the growth and progradation of ice across this region (Stollhofen et al, 2008;Le Heron et al, 2021). Boulder beds striated and polished surfaces, and subglacial shearing of unconsolidated sediments are documented across these regions and confirm subglacial and proglacial conditions (Figs.…”

Section: Kalahari Basinmentioning

confidence: 99%

“…In particular, the mid-to high-latitude Paraná and Kalahari basins of Brazil and Namibia, respectively, hosts arguably the world's highest fidelity record of this transition given the abundance of core and outcrop data across these passive intracratonic basins, the well-preserved nature of glacial record, and the large area over which glaciogenic deposits can be traced. Sedimentologic studies and detrital zircon geochronology have documented one of the richest Phanerozoic archives of the dynamic nature of late Paleozoic glaciation in this region, documenting a glaciogenic record characterized by multiple advance-retreat cycles before transitioning into post glacial marine or littoral depositional systems (Vesely et al, 2015;Mottin et al, 2018;Vesely et al, 2018;Fedorchuk et al, 2019a;Griffis et al, 2019b;Zieger et al, 2019Le Heron et al, 2021Dietrich et al, 2021). Furthermore, high-resolution U-Pb zircon chemical abrasion -thermal ionizing mass spectrometry (CA-TIMS) calibrated ages for these successions allows for the establishment of a multi-basin stratigraphic framework across this…”

Section: Introductionmentioning

confidence: 99%

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A Carboniferous apex for the late Paleozoic icehouse

Griffis

Mundil

Montañez

et al. 2023

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Icehouse climate systems occur across an abbreviated portion of Earth history, comprising ∼25% of the Phanerozoic record. The Late Paleozoic Ice Age (LPIA) was the most extreme and longest lasting glaciation of the Phanerozoic and is characterized by periods of acute continental scale glaciation, separated by periods of ice minima or ice-free conditions on the order of <10 6 years. The late Paleozoic glaciogenic record of the Paraná and Kalahari basins of southern Gondwana form one of the largest, best preserved, and well calibrated records of this glaciation. In the Carboniferous, the eastern and southern margins of the Paraná Basin and the Kalahari Basin were characterized by subglacial conditions, with evidence for continental and upland glaciers. In the latest Carboniferous, these basins transitioned from subglacial reservoirs to ice-free conditions evidenced by the widespread deposition of marine deposits juxtaposed on subglacial bedforms. High-precision U-Pb zircon CA-TIMS geochronologic constraints from volcanic ash deposits in the deglacial marine black shales of the Kalahari Basin and from fluvial and coal successions, which overlie marine deposits in the Paraná, indicate subglacial evidence in these regions is constrained to the Carboniferous. The loss of ice in these regions is congruent with a late Carboniferous peak in p CO 2 and widespread marine anoxia in the late Carboniferous. The permeant retreat of glaciers in basinal settings, despite an early Permian p CO 2 nadir, highlight the influence of short-term perturbations on the longer-term CO 2 record and suggests an ice-threshold had been crossed in the latest Carboniferous. A definitive driver for greenhouse gases in the LPIA, such as abundant and sustained volcanic activity or an increased biologic pump driven by ocean fertilization, is unresolved for this period. Lastly, the proposed Carboniferous apex for the high-latitude LPIA record is incongruent with observations from the low-latitude tropics where an early Permian peak is proposed.

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Section: Kalahari Basinmentioning

confidence: 99%

Section: Kalahari Basinmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Carboniferous apex for the late Paleozoic icehouse

Griffis

Mundil

Montañez

et al. 2023

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“…In areas with Dwyka Group sediments in Namibia, interpreted to be subglacial, the basal unconformity below diamictites may be highly irregular and heterogenous, with areas of sediment injections into the underlying basement, and 'elongated boul-ders' of sediment displaying fractures (Le Heron et al, 2021), i.e., an appearance partly similar to jigsaw-puzzle textures which are common in sediment gravity flow deposits (Dufresne et al, 2021;Molén 2021). Furthermore, in Namibia, Martin (1981) described 'pre-glacial valleys' that were glaciated and also crossed obliquely by glaciers.…”

Section: Geology Of the Dwyka Groupmentioning

confidence: 99%

Reconsidering the glaciogenic origin of Gondwana diamictites of the Dwyka Group, South Africa

Molén

Smit²

2022

Geologos

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The Gondwana Late Palaeozoic Ice Age is probably best represented by the Dwyka Group in South Africa. Striated and grooved surfaces or pavements are commonly considered to have formed subglacially, as are diamictites which have been interpreted as in-situ or reworked tillites. These interpretations were tested by investigation of outcrops in formerly well-studied areas, throughout South Africa. Detailed analyses have focused on striated surfaces/pavements and surface microtextures on quartz sand grains in diamictites. The sedimentological context of four pavements, interpreted to be glaciogenic, display features commonly associated with sediment gravity flows, rather than glaciation. A total of 4,271 quartz sand grains were subsampled from outcrops that are considered mainly to be tillites formed by continental glaciation. These grains, analysed by SEM, do not demonstrate the characteristic surface microtexture combinations of fracturing and irregular abrasion associated with Quaternary glacial deposits, but mainly a mix of surface microtextures associated with multicyclical grains. The Dwyka Group diamictites warrant reinterpretation as non-glacial sediment gravity flow deposits.

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“…In Western Gondwana, glacial stages or advances and retreats were frequent in the Carboniferous (Ezpeleta et al 2020, Le Heron et al 2021, López Gamundí et al 2021.…”

Section: A C C E P T E D Mmentioning

confidence: 99%

All post-Cambrian ichnospecies of Psammichnites Torell, 1870 belong to Olivellites Fenton and Fenton, 1937 b

Pazos

Gutiérrez

2022

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The ichnogenus Psammichnites herein restricted to Psammichnites gigas is based on comparison of morphology, feeding behaviour, contrast between the burrows and the host rock and possible producers. The record of siphonal activity as a “snorkel device” is discussed. The diagnosis of the ichnogenus Olivellites now is amended and includes all the records of Psammichnites in the post-Cambrian. Olivellites is now documented in successions other than the classical tidal flat deposits facies of the Carboniferous of the USA. We propose that the producer of Olivellites was an animal with capacity for displacement to different shallow infaunal levels for different feeding strategies. An interpretation of detritus feeding behavior with sediment displacement (pasichnia) is favoured here. The producer of Olivellites was likely to have been a bivalved mollusc that evolved after the Late Ordovician mass extinction. It was euryhaline and lived in a broad bathymetric range, and is recorded in temperate to glacially related successions. The material of Olivellites implexus from western Argentina is the youngest record of the ichnogegenus from Western Gondwana.

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The Late Palaeozoic Ice Age unconformity in southern Namibia viewed as a patchwork mosaic

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 8 publications

References 45 publications

A Carboniferous apex for the late Paleozoic icehouse

A Carboniferous apex for the late Paleozoic icehouse

Reconsidering the glaciogenic origin of Gondwana diamictites of the Dwyka Group, South Africa

All post-Cambrian ichnospecies of Psammichnites Torell, 1870 belong to Olivellites Fenton and Fenton, 1937 b

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