Atmospheric re-organization during Marine Isotope Stage 3 over the North American continent: sedimentological and mineralogical evidence from the Gulf of Mexico

• Drastic modifications of clay composition are evidenced in the GOM during MIS3.
• Changes of detrital provenance are linked to LIS extension or rainfall patterns.
• Different geographical areas of the LIS are active during major meltwater events.
• Two distinct atmospheric patterns controlled rainfall distribution over the US.
• Transitions between these configurations are likely driven by summer insolation.

Mineralogical and sedimentological records from the Gulf of Mexico (GOM) reveal major changes in the terrigenous particles provenance during the Marine Isotopic Stage 3 (MIS3) that likely resulted from modifications of the environmental conditions – including glacial activity and precipitation distribution – over the North American continent. The southeastern margin of the Laurentide Ice Sheet (LIS) was active throughout the entire MIS3, whereas the southwestern margin contributed to short-term meltwater events only during late MIS3. Some of the major mineralogical changes cannot be attributed to glacial activity but rather result from the changes in precipitation distribution. Combining sedimentological records from the GOM with previously published climate-related archives from the North American continent allows the reconstruction of two main schematic patterns of moisture inflow and precipitation distribution that may have prevailed during MIS3. Meltwater discharges contribute to modifying the LIS configuration and the GOM hydrological properties, ultimately affecting large-scale oceanic circulation and may have influenced atmospheric re-organizations although the insolation variation rate appears to be the main driver of the system.