--> Changes in Eocene-Miocene Shallow Marine Carbonate Factories Along the Tropical Southeast Circum-Caribbean Responded to Major Regional and Global Environmental and Tectonic Events

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Changes in Eocene-Miocene Shallow Marine Carbonate Factories Along the Tropical Southeast Circum-Caribbean Responded to Major Regional and Global Environmental and Tectonic Events

Abstract

Changes in the factory of Cenozoic tropical marine carbonates have been for long attributed to major variations on climatic and environmental conditions. Although important changes on the factories of Cenozoic Caribbean carbonates seem to have followed global climatic and environmental changes, the influence of tectonics on the occurrence, distribution and stratigraphy of shallow marine carbonate factories along this area is far from being well understood. Here we use sedimentologic characterization and multiple geochemical proxies to assess the influence of changing environmental conditions, tectonics and sea level change on the development of the shallow marine carbonate factories. During the Paleocene-early Oligocene interval, a period of predominant high atmospheric pCO2, coralline algae were the principal carbonate builders of shallow marine carbonate successions. The predominance of coralline red algae over corals on the shallow marine carbonate factories was likely related to high sea surface temperatures and high turbidity. Deposition of these factories was also controlled by diachronic opening of different sedimentary basins along the SE Circum Caribbean resulting from transpressional tectonics. Calcareous algae persisted until the middle Oligocene; a period when the drop of atmospheric pCO2 allowed the appearance of corals as the main constituents of the shallow marine carbonate factories by late Oligocene times. The late Oligocene interval is characterized by the occurrence of low diversity patchy coralline reefs, often mixed with siliciclastics. The occurrence of these patchy coralline successions occurred along rimmed mixed silicilastic/carbonate platforms and seems to have been related to low sea level. The lower Miocene interval is characterized by the development of rimmed carbonate platforms along which high diversity fringing coral reefs developed. The occurrence of these high diversity coralline carbonate factories was favored by a decrease in the siliciclastic input from the continents and further decrease in sea surface temperatures. Coral reef dominated the shallow marine carbonate factories until the middle Miocene, when a new period of calcareous algae reefs occurred along the Caribbean. This new change was the result of major changes in the Caribbean environmental conditions, which were driven by increased continental sediment runoff resulting from the exhumation of the northern Andes.