气候变化领域集成服务门户(CCPortal): Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada

CCPortal

DOI	10.1130/B35229.1
	Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada
	Wignall P.B.; Bond D.P.G.; Grasby S.E.; Pruss S.B.; Peakall J.
发表日期	2020
ISSN	167606
起始页码	918
结束页码	930
卷号	132 期号:2021-05-06
英文摘要	Microbially induced sedimentary structures (MISS) are reportedly widespread in the Early Triassic and their occurrence is attributed to either the extinction of marine grazers (allowing mat preservation) during the Permo-Triassic mass extinction or the suppression of grazing due to harsh, oxygenpoor conditions in its aftermath. Here we report on the abundant occurrence of MISS in the Lower Triassic Blind Fiord Formation of the Sverdrup Basin, Arctic Canada. Sedimentological analysis shows that mid-shelf settings were dominated by deposition from cohesive sand-mud flows that produced heterolithic, rippled sandstone facies that pass down dip into laminated siltstones and ultimately basinal mudrocks. The absence of storm beds and any other "event beds" points to an unusual climatic regime of humid, quiet conditions characterized by near continuous run off. Geochemical proxies for oxygenation (Mo/Al, Th/U, and pyrite framboid analysis) indicate that lower dysoxic conditions prevailed in the basin for much of the Early Triassic. The resultant lack of bioturbation allowed the development and preservation of MISS, including wrinkle structures and bubble textures. The microbial mats responsible for these structures are envisaged to have thrived, on sandy substrates, within the photic zone, in oxygen-poor conditions. The dysoxic history was punctuated by betteroxygenated phases, which coincide with the loss of MISS. Thus, Permo-Triassic boundary and Griesbachian mudrocks from the deepest-water settings have common benthos and a well-developed, tiered burrow profile dominated by Phycosiphon. The presence of the intense burrowing in the earliest Triassic contradicts the notion that bioturbation was severely suppressed at this time due to extinction losses at the end of the Permian. The notion that Early Triassic MISS preservation was caused by the extinction of mat grazers is not tenable. © 2019 The Authors.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184783
作者单位	School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom; Department of Geography, Geology and Environment, University of Hull, Hull, HU6 7RX, United Kingdom; Geological Survey of Canada, 3303 33rd Street N.W., Calgary, AB T2L 2A7, Canada; Department of Geoscience, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada; Department of Geosciences, Smith College, Northampton, MA 01063, United States
推荐引用方式 GB/T 7714	Wignall P.B.,Bond D.P.G.,Grasby S.E.,et al. Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada[J],2020,132(2021-05-06).
APA	Wignall P.B.,Bond D.P.G.,Grasby S.E.,Pruss S.B.,&Peakall J..(2020).Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada.Bulletin of the Geological Society of America,132(2021-05-06).
MLA	Wignall P.B.,et al."Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada".Bulletin of the Geological Society of America 132.2021-05-06(2020).