Barremian-Aptian Facies Diversity around the Tethys Realm: Global Oceanic Factors vs. Local Physiographic Conditions

Camilo Ponton 
Department of Earth Sciences, Florida International University
Miami, FL
cpont001@fiu.edu

Mid-Cretaceous oceans are known for their apparent widespread oxygen-poor conditions as attests the common occurrence of organic-rich (C-org) pelagic and hemipelagic sediments in the stratigraphic record of that time. However, comparison of Barremian-Aptian facies succession in southeastern France, northeastern Mexico, as reflected in their micro and macro-faunal assemblages, and carbon-carbonate content, produces contrasting results showing that fundamentally diverse sediments were synchronically deposited throughout sub-Tethyan basins under the same global oceanic conditions. In fact, Tethyan domains such as the northeastern Mexican basins show continuous deposits of C-org facies in the upper Barremian-Aptian while in southeastern France the Barremian-Aptian Urgonian facies exhibits thick packages of white to light-yellow rudistid limestones that are diachronous in the area.

Overall variation showing increasing occurrence of oceanic red-to-brown sediments from subordinate in the Mid-Cretaceous to dominant in the late Late Cretaceous and Paleocene, questions the exact controlling mechanisms of these facies. While this sedimentological change may indicate influences associated with paleoclimatic forcing mechanisms on the oxygen level of the water column, the occurrence of red sediments related to oxic conditions may also indicate arid climatic conditions that increased the input of terrigenous material into the oceans. The variety of these coeval facies implies that local physiography of the basin and related conditions of adjacent landmasses led to factors that could overprint the effects of global oceanic conditions.