Facies and evolution of the carbonate factory during the Permian–Triassic crisis in South Tibet, China

Abstract

The nature of Phanerozoic carbonate factories is strongly controlled by the composition of carbonate-producing faunas. During the Permian-Triassic mass extinction interval there was a major change in tropical shallow platform facies: Upper Permian bioclastic limestones are characterized by benthic communities with significant richness, for example, calcareous algae, fusulinids, brachiopods, corals, molluscs and sponges, while lowermost Triassic carbonates shift to dolomicrite-dominated and bacteria-dominated microbialites in the immediate aftermath of the Permian-Triassic mass extinction. However, the spatial-temporal pattern of carbonates distribution in high latitude regions in response to the Permian-Triassic mass extinction has received little attention. Facies and evolutionary patterns of a carbonate factory from the northern margin of peri-Gondwana (palaeolatitude ca 40°S) are presented here based on four Permian-Triassic boundary sections that span proximal, inner to distal, and outer ramp settings from South Tibet. The results show that a cool-water bryozoan-dominated and echinodermdominated carbonate ramp developed in the Late Permian in South Tibet. This was replaced abruptly, immediately after the Permian-Triassic mass extinction, by a benthic automicrite factory with minor amounts of calcifying metazoans developed in an inner/middle ramp setting, accompanied by transient subaerial exposure. Subsequently, an extensive homoclinal carbonate ramp developed in South Tibet in the Early Triassic, which mainly consists of homogenous dolomitic lime mudstone/wackestone that lacks evidence of metazoan frame-builders. The sudden transition from a cool-water, heterozoan dominated carbonate ramp to a warm-water, metazoan-free, homoclinal carbonate ramp following the Permian-Triassic mass extinction was the result of the combination of the loss of metazoan reef/mound builders, rapid sea-level changes across Permian-Triassic mass extinction and profound global warming during the Early Triassic.

Insight to the geological character of the Early Triassic strata in the Western Salt Range, Pakistan: A comparative study

“…The bioclastic limestone bears a simple fauna of bivalves and gastropods indicating a simple ecosystem consisting of microbes and primary consumers (Duan et al, 2018). The prevailing shallowing‐upward conditions and calcified microbial communities present in the Early Triassic rocks of South Tibet (Brühwiler et al, 2010; Li et al, 2019) are analogous with the facies and shallowing‐upward trend of the current study. But the carbonates of South China are thick, persisting into the middle Triassic and contain some of the Permian fauna.…”

“…These shales are analogous to the laminated, dark shales with high organic content reported from South China and India by Galfetti et al (2008). The rocks of the Triassic period in China are represented by relatively pure carbonates containing small biostromes and potentially reef builder calcified microbial communities (Duan et al, 2018; Li, Song, Woods, Dai, & Wignall, 2019; Tian et al, 2015). Because of the demise of a large proportion of frame builders in the aftermath of P–T mass extinction, it is highly unlikely for a characteristic rimmed shelf.…”

“…The Early Triassic Luolou Formation of Nanpanjiang Basin, South China, essentially has communities of low‐diversity bivalves, gastropods, ostracods, and rare foraminifera (Galfetti et al, 2008). The colonization of microbial limestones and development of a mixed siliciclastic‐carbonate environment in the Triassic Luolou Formation, South China (Baresel et al, 2017), dolomicritic‐microbialites‐dominated carbonate platform of Li et al (2019) in South Tibet, and microbialite‐dominated carbonate platform (Feixianguan Formation) of Duan et al (2018) in southwest China is in coincidence with the Early Triassic algal‐bearing mixed siliciclastic‐carbonates of Pakistan. This system had the presence of bryozoans, brachiopods, and plicate bivalves.…”

The Middle Permian (Capitanian) carbonate platform evolution and stratigraphic architecture of aNeo‐Tethysrim basin, Central Pakistan

“…Such rifting has caused the opening of Neo‐Tethys (Figure 1) and the development of a carbonate platform on the northwestern margin of Pakistan (Mertmann, 2003). Similar carbonate platforms are reported from various parts of the globe, for example, Tibet, Turkey, Europe, and Japan (Ezaki & Yao, 2000; Glennie, 1995; Lehrmann et al, 2003; Li, Song, Woods, Dai, & Wignall, 2019; Payne et al, 2007).…”

Ecological impact of fast industrialization inferred from a sediment core in Seocheon, West Coast of Korean Peninsula

“…As the Cyperaceae and Poaceae Fig. 6 Major heavy metal concentrations in the Yonghwasil-mot sediment core species favor the moist conditions (Hilbig 1995;Fowell et al 2003), the higher abundances of Cyperaceae and Poaceae (Gramineae) in this stage further support the predominant wetland environment (Zhu et al 2009;Miehe et al 2014;Li et al 2019), before construction of the Yonghwasil-mot as an agricultural reservoir. The elevated percentage of the Gramineae pollen is generally reflecting rice cultivation (e.g., Shen et al 2005;Park and Shin 2012); however, the low pollen density during this stage could be the result of low pollen inflow due to long dispersal distance or low pollen production (e.g., Van Campo et al 1996;Brewer et al 2017).…”