Radiocarbon chronology andδ13C analysis of mid-to late-Holocene aeolian environments, Guadalupe Mountains National Park, Texas, USA
1999
The Red Dunes of Guadalupe Mountains National Park are quartzose sand sheets and dunes stabilized by sparse plant cover. Stratigraphy, radiocarbon dating, and δ¹³C analysis were examined in two of the larger arroyos for correlating evidence of aeolian deposition, which in this basin is taken as an indication of arid conditions. Four quartz-sand lithostratigraphic units, representing intervals of aeolian activity, are identified. Radiocarbon dates provide constraint on the timing of the three youngest quartz-sand units. A mid-Holocene aeolian interval, represented by a single radiocarbon date of 6350± 70 BP, is interpreted as transitional to an altithermal regime. A neopluvial period, dated at 3370± 70 BP, separates mid-and late-Holocene aeolian activity. Late-Holocene time is characterized by generally drier conditions than present and almost continuous aeolian activity from 1690± 80 BP to 350± 0 BP. Stable carbon isotope analysis suggests an abrupt shift to generally cooler summer temperatures during this late-Holocene arid interval. While climate changes identified in the stratigraphic record broadly agree with changes reported elsewhere in the southwestern United States, differences in the timing of climate onset between this and adjacent regions suggest that climate change was time transgressive, and supports the recognition of the spatial and temporal variability of climates in response to local and regional controls.
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