Cretaceous( )-Paleocene uplift, drainage, and depositional basins along the southwestern margin of the Colorado Plateau, NW Arizona

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

OSTI ID:5095846

Young, R A ^[1]

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1. State Univ. of New York, Geneseo, NY (United States). Dept. of Geological Sciences

The SW margin of the Colorado Plateau has over 1,200 m of paleorelief partially buried by arkosic sediments with intercalated fossiliferous limestones of middle Eocene or greater age, indicating a Laramide origin for nearly 1.5 km of uplift by late Cretaceous or Paleocene time. The arkosic sediments contain 30-cm clasts currently 100 to 150 km from potential source areas bordering the plateau margin. Clast studies of stratigraphic sequences 150+ m thick and at elevations from 975 to 2,010 m (3,200 to 6,600 ft) demonstrate an initial unroofing of upper Paleozoic rocks from source terranes to the south and west, followed by an increase in the percentages of Precambrian quartzites and older crystalline basement clasts. These basal gravels give way to an influx of exotic volcanic debris (exceeding 50% of total clasts) with measured ages in the 63 to 80 Ma range. The upward change to predominantly exotic volcanic clasts in some sections is interpreted to record Laramide tectonism, erosion, and syntectonic sedimentation along the Plateau margin, accompanying late Cretaceous volcanism. Erosional unroofing of plausible Laramide source terranes beginning after volcanism could not have produced the observed vertical distribution of clasts. Clast lithologies also demonstrate a convergence of several distinct drainages toward the Hurricane fault structural zone, paralleling the northward trends of other Laramide monoclines. Stratigraphic and paleogeographic field relations at three sites suggest some monoclinal deformation accompanied sedimentation and paleocanyon incision. Thus a strong case exists for syntectonic Laramide sedimentation following Cretaceous uplift.

• OSTI ID: 5095846
• Report Number(s): CONF-9305259-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
COLORADO PLATEAU
SEDIMENTARY BASINS
GEOLOGIC DEPOSITS
PETROLOGY
SANDSTONES
STRATIGRAPHY
ARIZONA
CRETACEOUS PERIOD
DEPOSITION
GEOLOGIC HISTORY
LITHOLOGY
TERTIARY PERIOD
CENOZOIC ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
MESOZOIC ERA
MOUNTAINS
NORTH AMERICA
ROCKS
SEDIMENTARY ROCKS
USA
580000* - Geosciences