Van Horn Sandstone, Trans-Pecos Texas: Evidence for Late Cambrian rifting along southern North America

Conference · Mon Feb 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6002694

Hongshuan, Ye; Soegaard, K ^[1]

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1. Univ. of Texas, Dallas, TX (United States). Programs in Geosciences

The Van Horn Sandstone in the Trans-Pecos region of west Texas is interpreted as a rift sequence which developed in response to Cambrian breakup along the southern margin of the North American continent. The Van Horn Sandstone consists exclusively of braided alluvial sediments and occupies relatively small isolated basins in the vicinity of the town of Van Horn. The sandstone is in structural unconformable contact above intensely deformed Precambrian sediments which are < 1,123 Ma old. The Van Horn Sandstone is overlain by more than 650 meters of earliest Ordovician to Mississippian shallow-marine shelf sediments. Geohistory analysis of the overlying Paleozoic shelf sediments indicates that subsidence was driven by thermal contraction of the crust and that the shallow-marine sediments represent a drift sequence. Subsidence history curves correspond with theoretical thermal decay curves where [beta] = 1.2 and suggest that thermal subsidence commenced in Late Cambrian time about 510 Ma ago. Increased crustal attenuation, resulting in development of an ocean basin, occurred between Van Horn and the original location of deep water sediments presently exposed in the Marathon uplift to the south. Proposed Late Cambrian breakup south of Van Horn is coeval with rifting in the southern Oklahoma aulachogen and Rome trough in the Appalachian Mountains, but post-dates the main Late Proterozoic rifting event between 625 and 555 Ma along the eastern and western freeboard of North American. The significance of diachronous rifting in Eocambrian-Cambrian time is unclear at present but has consequences for fragmentation of the late Precambrian supercontinent Rodinia'.

• OSTI ID: 6002694
• Report Number(s): CONF-9303212--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:1
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CAMBRIAN PERIOD
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
NORTH AMERICA
PALEOZOIC ERA
PLATE TECTONICS
RIFT ZONES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STRATIGRAPHY
TECTONICS
TEXAS
USA