Reference Work Entry

Encyclopedia of Astrobiology

pp 48-54

Apex Chert, Microfossils

  • Daniele L. PintiAffiliated withGEOTOP & Department of Earth and Atmospheric sciences, Université du Québec à Montréal
  • , Wladyslaw AltermannAffiliated withDepartment of Geology, University of Pretoria Email author 

Keywords

Apex chert, apex basalt, biomarkers, cyanobacteria, microfossils

Definition

The Apex Chert is a bedded, microcrystalline silica (SiO2) deposit interlayered with pillow lavas and massive flows of the Apex Basalt Formation, Pilbara Craton, Western Australia. The basalts were dated at 3,465–3,458 Ma. The origin of the chert is disputed and interpretations of primary silica deposition on the ocean floor or alternatively secondary, hydrothermal silicification (chertification) of clastic or carbonate sedimentary and volcano-sedimentary rocks rival one another. The putative microfossils of Apex Chert are carbonaceous filaments found in ca. 3,465 Ma old chert lenses at the so-called “Schopf locality,” Chinaman Creek near Marble Bar.

Overview

The name of the locality derives from that of the American paleontologist and paleobiologist, J. William (Bill) Schopf, who, at this site, reported 11 morphological taxa of prokaryotic, filamentous, and coccoidal microfossils ...

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