Abstract
Microbial carbonates commonly flourished following mass extinction events. The end-Devonian (Hangenberg) mass extinction event is a first-order mass extinction on the scale of the ‘Big Five’ extinctions. However, to date, it is still unclear whether global microbial carbonate proliferation occurred after the Hangenberg event. The earliest known Carboniferous stromatolites on tidal flats are described from intertidal environments of the lowermost Tournaisian (Qianheishan Formation) in northwestern China. With other early Tournaisian microbe-dominated bioconstructions extensively distributed on shelves, the Qianheishan stromatolites support microbial carbonate proliferation after the Hangenberg extinction. Additional support comes from quantitative analysis of the abundance of microbe-dominated bioconstructions through the Famennian and early Tournaisian, which shows that they were globally distributed (between 40° latitude on both sides of the palaeoequator) and that their abundance increased distinctly in the early Tournaisian compared to the latest Devonian (Strunian). Comparison of variations in the relative abundance of skeleton- versus microbe-dominated bioconstructions across the Hangenberg and ‘Big Five’ extinctions suggests that changes in abundance of skeletal bioconstructors may play a first-order control on microbial carbonate proliferation during extinction transitions but that microbial proliferation is not a general necessary feature after mass extinctions.
Highlights
The Devonian-Carboniferous (D-C) transition was an important interval of biotic and palaeoenvironmental changes, characterized by the end-Devonian Hangenberg mass extinction event[1,2]
Rare earliest Carboniferous bioconstructions were dominated by stromatolites and/ or thrombolites[11,12], to date, it is unclear whether microbial carbonates that formed after the Hangenberg event represent a global microbial post-extinction proliferation or not
Increased microbial carbonate abundance generally was consistent with low metazoan diversity and high SCSS during mass extinction transitions, anomalies were present in some time slices, such as the end-Cretaceous when metazoan diversity declined and SCSS increased, but microbial carbonates did not resurge[10], possibly as a result of the flourishing calcareous plankton during this time[13]
Summary
The Devonian-Carboniferous (D-C) transition was an important interval of biotic and palaeoenvironmental changes, characterized by the end-Devonian Hangenberg mass extinction event[1,2]. Rare earliest Carboniferous bioconstructions were dominated by stromatolites and/ or thrombolites[11,12], to date, it is unclear whether microbial carbonates that formed after the Hangenberg event represent a global microbial post-extinction proliferation or not. The systematic study of changes in the abundance of skeleton- and microbe-dominated (i.e., bioconstructions formed by microbes, those composed of calcimicrobes) bioconstructions across mass extinction transitions could provide new insights into the controlling factors on broader microbial carbonate proliferation. Using the Paleoreefs database of Kiessling et al.[18] and new, recently published data[6,7,8,19,20,21,22,23], the relative abundance of skeleton- and microbe-dominated bioconstructions during the ‘Big Five’ and Hangenberg mass extinction transitions, was systematically reviewed, in order to compare the relationship between skeletal and microbial bioconstructors across the different mass extinction events. This paper aims to unravel (1) changes in the marine biosphere across the end-Devonian mass extinction transition; and (2) the dominant controlling factor on microbial carbonate proliferation after mass extinctions more generally
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