Hydro-climate of Subtropical North America since Last Glacial Maximum and Variations in the Dynamics of Atlantic and Pacific Moistures

English Abstract:

Modern day hydro-climate of subtropical North America (i.e. southern USA and northern Mexico) is controlled by the moisture sourced from both Atlantic and Pacific Oceans in the forms of summer as well as winter precipitations. Over the late last glacial and deglaciation, the dynamics of moisture from Pacific are better studied and geographical coverages of summer and winter precipitations are reconstructed by using several proxy records of continental deposits from southwestern USA and northwestern Mexico (Barron et al., 2012; Lyle et al., 2012; Kirby et al., 2013; Roy et al., 2013). The lack of records from northeastern Mexico and southeastern USA was a major hindrance for the reconstruction of dynamics of the moisture flow sourced from Atlantic. However, there is more paleoclimatic information from the eastern part of subtropical North America in the last decade (Grimm et al., 2003; Tripsanas et al., 2013; Feng et al., 2014). We present two different millennial-scale paleohydrological records from the northeastern and northwestern Mexico in order to reconstruct the dynamics of moisture sourced from both Atlantic and Pacific since the Last Glacial Maximum (LGM). Santiaguillo Basin located near the Pacific received more runoff during LGM and the amount of runoff decreased during deglaciation. The runoff record of El Potosi Basin located near the Atlantic is opposite of the Santiaguillo record and indicates more runoff during the deglaciation. The runoff into Santiaguillo over the Holocene was comparable with the proxy values of deglaciation, whereas El Potosi received less runoff during Holocene compared to the deglaciation. However both the sites registered reduced amount of runoff during the cooler Younger Dryas and Heinrich Stadial 1. Information about the variations in salinity, aeolian activity, productivity and source of productivity are reconstructed using multi-element concentrations, total organic carbon and C/N relation. A spatio-temporal reconstruction of the Atlantic moisture will be presented by comparing the paleohydrological information from northeastern Mexico with proxy records from Texas, Gulf of Mexico and Florida.