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Ancient iron formations - iron and silica-rich chemical sedimentary rocks that formed throughout the Precambrian eons - provide a significant part of the evidence for the modern …
Over million-year timescales, the geologic cycling of carbon controls long-term climate and the oxidation of Earth's surface. Inferences about the carbon cycle can be made from …
Magnesium is a major constituent in silicate and carbonate minerals, the hydrosphere and the biosphere. Magnesium is constantly cycled between these reservoirs. Since each of the …
Studies of Sr isotopic composition of thousands of samples of marine sediments and fossils have yielded a curve of 87Sr/86Sr versus age for seawater Sr that extends back to 1 …