Stromatolite reef from the Early Archaean era of Australia

Abstract

The 3,430-million-year-old Strelley Pool Chert (SPC) (Pilbara Craton, Australia) is a sedimentary rock formation containing laminated structures of probable biological origin (stromatolites). Determining the biogenicity of such ancient fossils is the subject of ongoing debate. However, many obstacles to interpretation of the fossils are overcome in the SPC because of the broad extent, excellent preservation and morphological variety of its stromatolitic outcrops--which provide comprehensive palaeontological information on a scale exceeding other rocks of such age. Here we present a multi-kilometre-scale palaeontological and palaeoenvironmental study of the SPC, in which we identify seven stromatolite morphotypes--many previously undiscovered--in different parts of a peritidal carbonate platform. We undertake the first morphotype-specific analysis of the structures within their palaeoenvironment and refute contemporary abiogenic hypotheses for their formation. Finally, we argue that the diversity, complexity and environmental associations of the stromatolites describe patterns that--in similar settings throughout Earth's history--reflect the presence of organisms.

Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa

“…Thus, cyanobacterial calcification is plausible at that time and was probably the most important rockforming process of biomineralization (Altermann, 2002. As life probably existed on Earth already at 3.8 Ga (Mojzsis et al, 1996;Rosing, 1999;McKeegan et al, 2007;Schopf et al, 2007), it would not be surprising to find evidence for cyanobacteria even in the 3.5 Ga Streely Pool stromatolitic reefs of Western Australia (Allwood et al, 2006). Thus, cyanobacteria may not only have shaped the face of the Earth by their influence on the composition of the atmosphere, but primarily by introducing a new rock type to the sedimentary inventory of our planet Earth.…”

“…Schopf et al, 2007;Glikson et al, 2008) and were formed by microbial ecosystems (microbial mats) (e.g. Hofmann et al, 1999;Tice and Lowe, 2004;Allwood et al, 2006), understanding of the genesis of such ancient rocks (3.5 Ga) and their possible relationships to modern living microbial mats and sites of carbonate rock formation, is inadequate (Grotzinger, 1989;Arp et al, 2001;Sumner and Grotzinger, 2004). The process of mineralization in microbial ecosystems in natural environments remains in general, but particularly in the Archean, one of the outstanding enigmas of carbonate rock formation, despite decades of intensive research and debate.…”

A deep subaqueous fan depositional model for the Palaeoarchaean (3.46 Ga) Marble Bar Cherts, Warrawoona Group, Western Australia

“…Sedimentary deposits of the Palaeoarchaean greenstones of the East Pilbara Craton, Western Australia, are of particular geological significance for hosting the oldest putative microfossils (Schopf, 1993;Schopf et al 2002), the oldest stromatolites (Allwood et al 2006;Van Kranendonk, 2006) and preserving evidence of the environmental conditions of the Early Earth (Robert & Chaussidon, 2006;Hoashi et al 2009;van den Boorn et al 2010). Among these rocks, the c. 3460 Ma Marble Bar Chert Member of the Duffer Formation (Warrawoona Group) is a typical Archaean red-white-grey banded chert remarkably exposed at the Marble Bar Pool and Chinaman Pool localities ( Fig.…”

A Review on Microbialites: a Korean Perspective

“…최근의 연구는 이들이 생물학적으로 생성되었으리라는 의견에 무게를 싣고 있다 (Hofmann et al, 1999;Allwood et al, 2006Allwood et al, , 2009. 스트로 마톨라이트 외에도 약 34억 6천만 년 전 퇴적된 오 스트레일리아의 아펙스 처트(Apex chert)에서 미생물 의 화석으로 생각되는 구조가 발견되었으나 (Schopf, 1994;Schopf et al, 2007), 이 구조가 생물 기원이 아니라는 견해도 존재한다 (Pinti et al, 2009;Brasier et al, 2015).…”