Abstract

The paleoclimatic variability of northern Mexico since the Late Wisconsinan is determined from sedimentological, geochemical, and stratigraphic studies of the lacustrine sequence of Laguna Babícora (29.4°N, 107.7°W; elevation 2100 m asl). Chronological control is based on 13 radiocarbon dates (6 from this study and 7 previously reported) from four stratigraphic profiles that cover a range from 16 342 to 2800 BP. Two major periods of increased humidity are recognized by lake-level variation during the Late Wisconsinan and early Holocene. The Late Wisconsinan humid period may be related to jet stream migration to southerly latitudes and the influence of the mobile polar high. This period has been identified in the sedimentary record of El Diablo profile with a radiocarbon date of 16 342 ± 201 BP. The early Holocene humid period is recorded in El Diablo (10 976 ± 115 BP) and Cano profiles (9614 ± 130 BP). It is interpreted as a result of the Younger Dryas climatic anomaly characterized by a temperature decrease and cold paleoclimatic conditions similar to those for the Late Wisconsinan. The early Holocene was followed by an overall gradual drying that reached a maximum around 6000 BP, during the middle Holocene. For the late Holocene evidence of widespread erosion, sedimentation changes, flooded surfaces, and paleosoils indicates that Laguna Babícora was subjected to short-term climatic changes.

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