Tertiary and Quaternary tectonics of the Hueco bolson, Trans-Pecos Texas and Chihuahua, Mexico

Abstract

The Hueco bolson of Trans-Pecos Texas formed in response to Cenozoic extensional tectonism and lies within the southern Rio Grande rift near the poorly defined boundary between the rift and the southern Basin and Range province. The bolson is composed of a northwest subbasin that contains north-striking normal faults and a southeast subbasin that contains northwest-striking normal faults. Cenozoic basin fill is thin (less than 150 to 200 m) on the east and northeast bolson margins and is thick (as much as 2,850 m) in the central bolson and on the west and southwest bolson margins where major normal faults bound a graben that is 15 to 25 km wide. Major faults bounding the graben on the west and southwest have been more active and exhibit greater offset than do boundary faults on the east. This disparity in displacement between the graben margins has resulted in an asymmetric graben. Isopach maps of lower and upper basin fill sequences, differentiated from seismic data, indicate that much of the southeast Hueco bolson subsided more than the northwest Hueco bolson during deposition of the lower basin fill. Thicker upper basin fill within the northwest basin indicates that the basin subsided more in the northwest than in the southeast during deposition of the upper basin fill.The two major faults that bound the Hueco graben on the west and southwest, the East Franklin Mountains fault and Amargosa fault, respectively, have had the most recent (late Pleistocene-Holocene) surface ruptures. Scarp-slope angles of these faults are commonly steeper than 20°, and middle Pleistocene surficial deposits that contain indurated calcic soils having stage IV to V morphology are offset between 24 and 32 m. Maximum throw on these faults during single surface-rupture events has been between 1.6 and 3 m. Major faults bounding the southeast Hueco graben on the northeast (Campo Grande, Caballo, and an unnamed fault) had their most recent surface ruptures during the late Pleistocene. Scarp-slope angles of these faults are rarely as much as 15° and more commonly between 4 and 7°. Middle Pleistocene surficial deposits that contain indurated calcic soils having a stage IV to V morphology are offset between 1.6 and 24 m. Maximum throw on these faults during single surface-rupture events has been between 0.6 and 2 m.

The historical biogeography of the southern group of the sucker genusMoxostoma(Teleostei: Catostomidae) and the colonization of central Mexico

“…A), which was active during the Late Eocene–Oligocene (Flotté et al ., ), and supports the existence of a former miocenic Bravo River that is likely to have been inhabited by the MRCA of the species complex. Additionally, the earliest known river deposits of an ancestral Upper Bravo River in the southern part of the ‘Río Grande Rift’ (Flotté et al ., ) and the ‘Hueco Bolson’ (Collins & Raney, ) were dated to 2.3 and 2.1 Myr, respectively, indicating a more recent event; therefore, the connection between the Bravo River and the western Gulf slope of North America was probably limited through the Lower Bravo, at least before these dates.…”

Geochronology of the Bolson sand sheet, New Mexico and Texas, and its archaeological significance

“…The Bolson sand sheet is located in a downfaulted valley or bolson in the eastward extension of the Basin and Range Province (Collins and Raney, 1994). It covers an area of ~4440 km 2 (1714 square miles) in the Tularosa Valley of New Mexico and the Hueco Bolson of Texas (Fig.…”

Three-dimensional hydrogeologic framework model of the Rio Grande transboundary region of New Mexico and Texas, USA, and northern Chihuahua, Mexico

“…The lineament is believed to have been most active during the Precambrian but may have had repeated periods of offset (Muehlberger, 1980). Northweststriking, graben-bounding normal faults in the Hueco Bolson of the border region of Texas may be controlled by the Texas lineament (Muehlberger, 1980;Collins and Raney, 1994). Muehlberger (1980) inferred the lineament to be a broad distributed zone of shear tens of kilometers wide.…”