Modeling hydrography and marine sedimentation in the Cariaco Basin since the Last Glacial Maximum

Abstract

The Cariaco Basin has shallow connections with the Caribbean Sea, and these are further reduced at times of lower sea level, such as at the Last Glacial Maximum (LGM). A numerical model was developed to describe the oceanography and biogenic sedimentation in the Cariaco Basin and nearby Caribbean. The model is run with different sea levels in order to simulate the changing oceanography and the development of deep water anoxia in the Cariaco Basin since the LGM. In the main sequence of numerical experiments, the surface forcing is kept fixed at present-day values while the sea level is changed in order to separate the effects of sea level from the effects of climate. As the sea level rises, the main sedimentation zone moves first to the shallow broad northern sill and NE part of the Cariaco Basin and then, once sea level reaches approximately 60 m below present, moves south to the northern coast of mainland Venezuela. The model shows that there would be an overall increase in sedimentation in the basin as the sea level rises, even if there was no change in the surface forcing. However, the model also shows that sedimentation at particular points in the basin exhibits more complicated behavior, which needs to be taken into account when interpreting individual records. Preliminary numerical experiments examine the effects of changing surface forcing while keeping the sea level at LGM values, and the applicability of a mathematical hydraulic control model in this case is also considered. Copyright 2009 by the American Geophysical Union.