Basin-Fill Stratigraphy, Quaternary History, and Paleomagnetics of the Eagle Flat Study Area, Southern Hudspeth County, Texas


Data and analyses of basin-fill stratigraphy, paleomagnetics, Quaternary history, and pseudo-fissures/fissures were acquired and interpreted by the Bureau of Economic Geology (BEG) in the Eagle Flat study area in southern Hudspeth County, Texas. These investigations were funded by the Texas Low-Level Radioactive Waste Disposal Authority (the Authority) as part of the evaluation of a proposed site for the Texas low-level radioactive waste repository. Data and information developed as a result of these investigations will be used to evaluate the proposed waste repository site and surrounding region and to provide data for performance assessment, design, and licensing activities. Basin-fill sediments are composed predominantly of sandy mud and mud; sands are abundant at the surface in the vicinity of the proposed repository site, and gravels are abundant at the base of the basin fill adjacent to the bedrock. Basin-fill thickness ranges from 163 ft (50 m) on the southeast side of the proposed site to 715 ft (218 m) on the northeast side of the proposed site. Basin-fill thickness is approximately 200 ft (61 m) on the west side of the proposed site. Coarser basin-fill deposits are interpreted as proximal alluvial fans and colluvium, and finer sands and muds are interpreted as ephemeral stream, distal alluvial fan, alluvial flat, and eolian deposits. At the proposed site, near-surface fine gravel and coarse to fine sand deposits exhibit characteristics consistent with fluvial deposition. Some well-sorted fine-grained sands have textures consistent with eolian sediments. Fine-grained sands and muds are interpreted as distal alluvial fan and ephemeral stream deposits.


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