气候变化领域集成服务门户(CCPortal): Paleoproterozoic (ca. 1.9 Ga) megascopic life on land in Western Australia

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DOI	10.1016/j.palaeo.2019.109266
	Paleoproterozoic (ca. 1.9 Ga) megascopic life on land in Western Australia
	Retallack G.J.; Mao X.
发表日期	2019
ISSN	0031-0182
卷号	532
英文摘要	Controversial hairpin-shaped trace fossils (Myxomitodes stirlingensis) and discoid fossils (Cyclomedusa davidi) are here reinterpreted in a reassessment of sedimentology and paleosols of the 1.9 ± 0.1 Ga Stirling Range Formation of Western Australia. Paleosols in the Stirling Range Formation were recognized from complex cracking patterns (peds and cutans), chemical and mineralogical zonation (soil horizons), and poikiloblastic crystals (desert roses). Redox profiles of the paleosols are evidence of well-drained profiles of a coastal plain under a low oxygen (433 ± 116 ppmv) and carbon dioxide (564 ± 64 ppmv) atmosphere. Gypsum pseudomorphs in paleosols that are deeply weathered chemically, represent a persistence of acid sulfate weathering, better known in Archean paleosols before the Great Oxidation event at 2.45 Ga. Chemical composition of the paleosols is evidence of a humid (1478 ± 182 mm mean annual precipitation) temperate (11.3 ± 0.5 °C mean annual temperature) paleoclimate. Their paleoenvironmental setting was a coastal plain on a passive tectonic margin. Megafossils were found on paleosols of western red sandstones of the Stirling Range Formation, not in gray shales and sandstones of marine facies to the east. Trace fossils (Myxomitodes stirlingensis) and discoid fossils are both found at the surface of well drained paleosols, and so were not metazoan trails, nor sea jellies. Myxomitodes was more likely a grex (“slug”) trail of soil slime molds, and the Cyclomedusa discoids, were probably microbial colonies. Pervasive microfilamentous structures in the paleosol surface are additional evidence of Paleoproterozoic microbial earth ecosystems. © 2019 Elsevier B.V.
英文关键词	Microbial earth; Mycetozoa; Paleoclimate; Paleosol; Stirling Range Formation
语种	英语
scopus关键词	Archean; assessment method; chemical composition; chemical method; coastal plain; Earth; metazoan; microbial activity; mineralogy; paleoclimate; paleoenvironment; paleosol; Proterozoic; redox conditions; sedimentology; shale; trace fossil; Australia; Stirling Range; Western Australia; Discoidae; Metazoa; Mycetozoa; Myxogastria; Rosa
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150848
作者单位	Department of Earth Science, University of Oregon, Eugene, OR 97403-1272, United States; Institute of Geography, Fujian Normal University, Fuzhou, 350007, China
推荐引用方式 GB/T 7714	Retallack G.J.,Mao X.. Paleoproterozoic (ca. 1.9 Ga) megascopic life on land in Western Australia[J],2019,532.
APA	Retallack G.J.,&Mao X..(2019).Paleoproterozoic (ca. 1.9 Ga) megascopic life on land in Western Australia.Palaeogeography, Palaeoclimatology, Palaeoecology,532.
MLA	Retallack G.J.,et al."Paleoproterozoic (ca. 1.9 Ga) megascopic life on land in Western Australia".Palaeogeography, Palaeoclimatology, Palaeoecology 532(2019).