Unformatted text preview: platform margin. Deep subtidal microbial lithofacies contain a minimum of 20% calcite cement on average. One 40 m section contains 65% herringbone, bladed, blocky, and microcrystalline cements that precipitated on and in microbial mats. The remaining 35% is recrystallized, but probably also consisted of in situ precipitated calcite. Thus, precipitation of calcite and aragonite on the sea floor was very important in accumulation of the platform. Other Late Archean carbonates, including those in the Belingwe and Bulawayo greenstone belts, Zimbabwe, and the Steeprock greenstone belt, Canada, also contain abundant sea floor-encrusting calcite and aragonite in a variety of depositional environments. The large volume of marine cement demonstrates that in situ calcite and aragonite precipitation was a more important platform-building process for Late Archean carbonates than it was for younger platforms....
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- Spring '08
- Plate Tectonics, Calcium carbonate, carbonate minerals, Calcite, Aragonite, aragonite precipitation