Contrasting rainfall patterns over North America during the Holocene and Last Interglacial as recorded by sediments of the northern Gulf of Mexico

Abstract : The comparison of geochemical and mineralogical characteristics of terrigenous sediments deposited in the northern Gulf of Mexico (GoM) during the Holocene and Last Interglacial (LIG) is used to document the impact of slight differences in insolation and ice-sheet retreat rates on moisture transfer and precipitation patterns over central North America. The records indicate distinct sedimentological signatures over the two time periods, which likely reflect a modification of the main detrital provenance during the LIG compared to the Holocene. Here we postulate that the observed differences in the terrigenous supply during the LIG relative to the Holocene reflect a northeast migration of the main precipitation belt over the Mississippi River watershed likely in response to deglaciation of the Laurentide Ice Sheet prior to the peak in boreal summer insolation and the overall greater increase in boreal summer insolation relative to the Holocene. These combined effects allowed more northward migration of the Jet Stream, Atlantic Warm Pool and Intertropical Convergence Zone than during the Holocene, which may have also forced the Bermuda High farther to the northeast of its present position, thereby pumping more moisture from the GoM and the Caribbean region into both the Upper Mississippi River and northeast Great Lakes area. Citation: Montero-Serrano, J.-C., et al. (2011), Contrasting rainfall patterns over North America during the Holocene and Last Interglacial as recorded by sediments of the northern Gulf of Mexico