Michael M Tice

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Recent re-evaluations of the geological record of the earliest life on Earth have led to the suggestion that some of the oldest putative microfossils and carbonaceous matter were formed through abiotic hydrothermal processes. Similarly, many early Archaean (more than 3,400-Myr-old) cherts have been reinterpreted as hydrothermal deposits rather than products(More)
Stable oxygen isotope ratios (delta(18)O) of Precambrian cherts have been used to establish much of our understanding of the early climate history of Earth and suggest that ocean temperatures during the Archaean era ( approximately 3.5 billion years ago) were between 55 degrees C and 85 degrees C (ref. 2). But, because of uncertainty in the delta(18)O of(More)
Figure 1 | Mat finish. Noffke et al. find features in 2.9-billion-year-old rocks from the Pongola Supergroup in South Africa that are similar to those caused by microbial mats in intertidal zones today (left, fossil Pongola feature; right, contemporary feature for comparison): a, uprooted and redeposited mat chips; b, overfolded rock chips; c, oscillation(More)
Iron-bearing early diagenetic carbonate cements are common in sedimentary rocks, where they are thought to be associated with microbial iron reduction. However, little is yet known about how local environments around actively iron-reducing cells affect carbonate mineral precipitation rates and compositions. Precipitation experiments with the iron-reducing(More)
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