Triassic Foraminifera from the Great Bank of Guizhou, Nanpanjiang Basin, south China: taxonomic account, biostratigraphy, and implications for recovery from end-Permian mass extinction

Abstract

Foraminifera are important components of tropical marine benthic ecosystems and their recovery pattern from the end-Permian mass extinction can yield insights into the Mesozoic history of this group. Here we report the calcareous and agglutinated foraminifera recovered from five measured stratigraphic sections on the Great Bank of Guizhou, an uppermost Permian to Upper Triassic isolated carbonate platform in the Nanpanjiang Basin, south China. The material contains >100 Triassic species, including three that are newly described (Arenovidalina weii n. sp., Meandrospira? enosi n. sp., and Spinoendotebanella lehrmanni n. gen., n. sp.), ranging from Griesbachian (Induan) to Cordevolian (Carnian) age. The species belong to the classes Miliolata, Textulariata, Fusulinata, Nodosariata, and to an unknown class housing all aragonitic forms of the orders Involutinida and Robertinida. Based on previously established conodont zones and carbon isotope chemostratigraphy, the Griesbachian (early Induan) through Illyrian (late Anisian) interval has been subdivided into 12 foraminiferal zones and two unnamed intervals devoid of foraminifera. Following the extinction at the Permian-Triassic boundary, habitable ecological niches of Griesbachian age were invaded by disaster taxa that subsequently became extinct during the Dienerian (late Induan) and left no younger descendants. The disaster taxa were replaced by Lazarus taxa with Permian origins, which were then decimated by the Smithian-Spathian (mid-Olenekian) boundary crisis. The tempo of recovery appears to have been modulated by environmental changes during the Griesbachian through Smithian that involved both climate change and expansion of anoxic ocean bottom waters. Uninterrupted and lasting recovery of benthic foraminifera did not begin until the Spathian. UUID: http://zoobank.org/2a6e9061-b163-402a-9098-8765a80576b3

Fossilized eukaryotes from 2.7 billion year old shales in Tanzania

“…The overall shape of the organism super cially resembles the testate amoeba Di ugia bacillariarum 41 , which test sports one to two slightly off centre projections on the end opposite the aperture. The organisation of semi-enclosed, conjoined spheroids making up the test is reminiscent of some multiocular foraminifera 42 . Bayesian molecular dating suggests that Foraminifera rst evolved in the Cryogenian, around 770 Ma, with the rst undisputed foraminiferal test dating to ~545 Ma 43 .…”

The role of carbonate factories and sea water chemistry on basin‐wide ramp to high‐relief carbonate platform evolution: Triassic, Nanpanjiang Basin, South China

“…This study focuses on the Yangtze Platform margin cross-section exposed on the limb of a north-west trending syncline at Guanling (Figure 1B,C) and the northern margin of the GBG exposed on the eastern limb of the north-trending syncline at Bianyang (Figure 1B,D). Previous work has constrained the stratigraphic architecture and sequence stratigraphy, and developed a mature chronostratigraphy using conodont and foraminifera biostratigraphy integrated with palaeomagnetic reversal stratigraphy, chemostratigraphy and geochronology (Altiner et al, 2021;Enos et al, 2006;Kelley, 2014;Kelley et al, 2020;Lehrmann et al, 1998Lehrmann et al, , 2015Minzoni, 2007;Minzoni et al, 2013Minzoni et al, , 2015Payne et al, 2004).…”