Provenance of sediments deposited at paleolake San Felipe,western Sonora Desert: Implications to regimes of summer and winter precipitation during last 50 cal kyr BP |
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| Institution: | 1. Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, USA;2. School of Geography Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK;1. Marine Palynology and Paleoceanography, Laboratory of Paleobotany and Palynology, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, P.O. box 80.115, 3508TC Utrecht, The Netherlands;2. NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands |
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| Abstract: | Rare earth element, major and trace element and mineralogy in the sediments representing last 50 cal kyr BP from the summer precipitation fed paleolake San Felipe identify the different association of minerals and selective transportation of different grain size fractions and relate them to the variation in pluvial discharge into the basin as well as aeolian activities in the western Sonora Desert. Period of lower pluvial discharge during 14–48 cal kyr BP is contemporary to the regime of dominant winter storms in the region. Transportation of coarser quartz and plagioclase during 40–48 cal kyr BP and dominant finer fractions during 14–40 cal kyr BP possibly mirror the variation in the frequency of winter storms. During 3–14 cal kyr BP, higher catchment erosion (sedimentation increased 4–12 times) and transportation of REE bearing heavy minerals into the basin indicate higher pluvial discharge. We relate this period to a regime of dominant summer precipitation associated with the North American Monsoon and tropical cyclones. Geochemical and mineralogical signatures of the sediments deposited during ca. 8, 12–13 and >48 cal kyr BP suggest selective mobilization of quartz and plagioclase from the surrounding sand dunes by the aeolian processes. |
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