Rare calcareous microfossils from Middle Miocene strata, Weddell Sea off Antarctic Peninsula

Abstract

Abstract:The calcareous microfossil assemblage from Middle Miocene strata of SHALDRIL Site NBP0602A−5D consists of benthic foraminifera, ostracods, bivalves, and gastropods, and is interpreted as shallow−water. It appears to be reworked but its age is probably similar to the age of the host sediment, which contains only rare, fragmented, agglutinated foraminifera. Most of the calcareous taxa are of uncertain taxonomic affiliation, due to the scarcity of Ceno− zoic microfossils of this age from West Antarctica, and also the very different paleohabitat of this now extinct assemblage.

Polish Polar Research

“…In addition, the carbonate compensation depth (CDD) could be very shallow at least in some parts of the Southern Ocean by at least the Miocene, as suggested by the contrast between the abundant and well-preserved foraminifera of extremely shallow paleoenvironments with the scarce and poorly preserved specimens of slightly deeper-water settings in Miocene sediments of the Fisher Bench Formation (East Antarctica) (Majewski et al 2017) and of the Weddell Sea (Majewski et al 2012). In fact, the shallow Antarctic CCD could have its roots in the Paleogene, what would help to explain the predominance of shallowwater assemblages over deeper ones in the Cenozoic foraminiferal record of Antarctica (see Majewski et al 2017 for further discussion).…”

A deep-sea foraminiferal assemblage scattered through the late Cenozoic of Antarctic Peninsula and its biostratigraphic and biogeographic implications

“…For West Antarctica, the reported assemblages represent mainly communities of shallow, inner-shelf settings that are Eocene to Pleistocene in age (e.g., Birkenmajer and Łuczkowska, 1987;Gaz ́dzicki and Webb, 1996;Gaz ́dzicki and Majewski, 2012;Caramés and Concheyro, 2013;Majewski and Gaz ́dzicki, 2014), whereas those from deeper paleoenvironments are represented by some Miocene assemblages (Birkenmajer and Łuczkowska, 1987) and a couple of Paleocene ones (Huber, 1988; see paleoenvironmental revisions by Olivero et al, 2007 andMarenssi et al, 2012). For East Antarctica, it is the opposite, for very few occurrences from shallow, marine settings are known (see Quilty et al, 2010;Majewski et al, 2012Majewski et al, , 2017 and some outer-shelf to abyssal assemblages have been recovered from offshore deposits (see Thomas, 1989;Majewski et al, 2018). Notwithstanding this uneven but paleoecologically diverse record, occurrences of flysch-type assemblages-the most common and well-studied assemblage type of deep-sea agglutinated foraminifers-has remained unknown for both West and East Antarctica, including nearby offshore areas.…”

Miocene and Plio-Pleistocene foraminiferal assemblages from Seymour Island, Antarctica

“…The notorious patchiness of the foraminiferal fossil record of West Antarctica prevents a comprehensive view of its Cenozoic faunas, but a few assemblages are known from the following deposits: Cretaceous–Palaeocene López de Bertodano Formation and Palaeocene Sobral Formation on James Ross Island, Seymour Island and Vega Island (Huber 1986, 1988); Eocene La Meseta Formation on Seymour Island (Gaździcki & Majewski 2012; see also Bitner 1996 for brachiopod-incrusting foraminifers and Badaró 2019 for rare agglutinated specimens); Oligocene Polonez Cove Formation on King George Island (Gaździcki 1989, Majewski & Gaździcki 2014); Early Miocene Cape Melville Formation, also on King George Island (Birkenmajer & Łuczkowska 1987), Middle Miocene deposits off Weddell Sea (Majewski et al 2012) and Miocene Hobbs Glacier Formation (HGF) on James Ross Island (Jonkers et al 2002, Concheyro et al 2007); Pliocene Cockburn Island Formation on the homonymous island (Hennig 1910, Holland 1910, Gaździcka & Gaździcki 1994, Gaździcki & Webb 1996); and Pleistocene deposits on Vega Island (Caramés & Concheyro 2013, Concheyro et al 2014).…”