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Distribución de foraminíferos en el santoniense y su relación con el evento anóxico eao3: formación la luna, río San Miguel, estado Mérida

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Publisher
Revista de la Facultad de Ingeniería Universidad Central de Venezuela
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Keywords
  • La Luna Formation
  • Maracaibo Basin
  • Santonian
  • Planktic And Benthic Foraminifera
  • Ocean Anoxic Event
  • Climate Change

Abstract

The La Luna Formation, in the San Miguel river section, is characterized by black marlstones interbedded with black limestones deposited under anoxic/dysoxic conditions in the upper neritic to upper bathyal environment. Changes in foraminifera assemblages provide insights into factors that influenced the accumulation of organic-rich deposits during Santonian time. The benthic foraminifera data suggests that the general trend in the accumulation of carbon-rich deposits in this region was mainly controlled by variations in dissolved oxygen at the sediment-water interface in the early Santonian.During the late Santonian a cooling-trend in global climate increased wind strength and upwelling, this change probably reduced runoff causing a weakening of the pycnocline and destabilized the stratification in the water column, decreasing the total organic carbon preservation in a shallower basin. Global climate change and the establishment of full mid- and deep-water exchange in response to the deepening and widening of the Equatorial Atlantic Gateway could have been important mechanisms for ending the region-wide anoxia that was common in northern South America during the Late Cretaceous.

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