QUATERNARY GEOMORPHIC SYSTEMS AND PALEOENVIRONMENTAL RECONSTRUCTION IN THE GUADALUPE MOUNTAINS REGION, WEST TEXAS AND SOUTH-CENTRAL NEW MEXICO, USA

The purpose of this poster is to introduce preliminary results from our examination of the Quaternary geomorphic systems of the Guadalupe Mountains Region (GMR) of west Texas and south-central New Mexico. This research has two streams: (1) investigation of quartz and gypsum sand dunes in the region, and (2) an analysis of soils, paleosols, and stratigraphy on alluvial fans. The ultimate purpose of this research is to integrate dated events occurring within both systems in order to reconstruct paleoenvironmental conditions, and to compare the responses of these systems to existing climate-geomorphologic response models.

Stratigraphy and dating of the aeolian deposits in the Salt Basin section of the GMR indicates several periods of aeolian activity probably beginning in the late Pleistocene. The quartz sand dunes in the region can be subdivided into older (mid-Holocene) stabilized dunes and sand sheets, and younger nebkha dunes. Current aeolian activity in the region is limited to gypsum dunes and is controlled primarily by surface production of gypsum through evaporative pumping and the deflation of existing gypsum dunes due to anthropogenic activities. One aspect of this research will be determining if aeolian activity is a function of climate change or other factors such as sediment supply and availability.

The western escarpment of the Guadalupe Mountains is mantled by a large bajada that is thought to have formed in the late Pleistocene. Fan dissection, vegetation growth in apical channels, and development of soils on fan surfaces seem to indicate that fan-forming processes have diminished in recent time. Carbonate and possibly gypsum cemented soil horizons and sediment layers have been identified on fan surfaces and in the subsurface throughout the region, and determination of carbonate stage of surface soils and paleosols and radiocarbon and uranium-series dating is under way. These data along with carbon and oxygen isotopes analysis of carbonate cemented soil will be used to establish a geochronology for the region and can then be correlated with data from the dune system.