Sedimentology of Muddy Creek Formation, southern Nevada: fluvial-lacustrine basin-fill deposition in Basin and Range province

Conference · Wed Mar 01 00:00:00 EST 1989 · AAPG Bull.; (United States)

OSTI ID:5880802

Keefer, S; Walker, J D

The Muddy Creek Formation provides a unique three-dimensional exposure of a post-tectonic basin-fill deposit in the Basin and Range province. This Miocene-Pliocene sequence is exposed in Meadow Valley Wash north of the Lake Mead region in southern Nevada. Exposure of basin deposits is excellent because of effects of downcutting in the Colorado/Virgin River drainage systems. Muddy Creek grades laterally from coarse-grained facies at the basin margin to medium to fine-grained fluvial facies and ultimately to fine-grained marginal-transitional lacustrine facies in the basin axis. Basin margin facies consist of conglomerate and eolian sandstone. Lacustrine facies represent vertically aggrading sequences whereas transitional basin margin facies aggrade laterally, with fine-grained sediments onlapping the basin-bounding ranges. Paleocurrent and petrologic evidence, such as the presence of abundant quartz, frosted grains, volcanic fragments, and petrified wood, indicate the principal source for the Muddy Creek sediments was the Triassic Moenkopi and Chinle Formations and Cretaceous/Tertiary volcanics located at the north end of Meadow Valley Wash. The Muddy Creek Formation is an unfaulted, undeformed sequence indicating deposition occurred after cessation of Basin and Range faulting. Further evidence for a post-tectonic origin is that basin facies do not show lateral shifts that would be expected in a tectonically active extensional basin. Drainage patterns, therefore, appear to be essentially unchanged over the last 8 m.y. This study indicates that facies shifts rather than vertical successions alone may be the best gauge of syn-tectonic vs. post-tectonic origin for basin deposits.

• Research Organization: Univ. of Kansas, Lawrence (USA)
• OSTI ID: 5880802
• Report Number(s): CONF-890404-
• Journal Information: AAPG Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23-26 Apr 1989
• Country of Publication: United States
• Language: English

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