منابع مشابه
Sulfate was a trace constituent of Archean seawater.
In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column of Lake Matano, Indonesia, a low-sulfate analog for the Archean ocean, we find large (>20 per mil)...
متن کاملPrecambrian geology: geological evolution of the Earth during the precambrian.
Give us 5 minutes and we will show you the best book to read today. This is it, the geological evolution of the earth during the precambrian that will be your best choice for better reading book. Your five times will not spend wasted by reading this website. You can take the book as a source to make better concept. Referring the books that can be situated with your needs is sometime difficult. ...
متن کاملEpisodic Precambrian subduction
The Precambrian geological record shows peak of activity at 1.1, 1.9–2.1, 2.7 and 3.5 Ga, often associated with massive crustal production, orogenesis and supercontinent cycles. It has been suggested that these bursts of tectonic activity are due to mantle avalanche events, where accumulating subducted slabs periodically penetrate the 670 km discontinuity, and subsequent upwelling counterflow a...
متن کاملSeawater Mg/Ca controls polymorph mineralogy of microbial CaCO3: a potential proxy for calcite-aragonite seas in Precambrian time.
A previously published hydrothermal brine-river water mixing model driven by ocean crust production suggests that the molar Mg/Ca ratio of seawater (mMg/Ca(sw)) has varied significantly (approximately 1.0-5.2) over Precambrian time, resulting in six intervals of aragonite-favouring seas (mMg/Ca(sw) > 2) and five intervals of calcite-favouring seas (mMg/Ca(sw) < 2) since the Late Archaean. To ev...
متن کاملPrecambrian Lunar Volcanic Protolife
Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and volcanic shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over ge...
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ژورنال
عنوان ژورنال: Nature
سال: 1982
ISSN: 0028-0836,1476-4687
DOI: 10.1038/296309a0