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Detrital zircon U-Pb provenance of the Colorado River; a 5 m.y. record of incision into cover strata overlying the Colorado Plateau and adjacent regions

David L. Kimbrough, Marty Grove, George E. Gehrels, Rebecca J. Dorsey, Keith A. Howard, Oscar Lovera, Andres Aslan, P. Kyle House and Philip A. Pearthree
Detrital zircon U-Pb provenance of the Colorado River; a 5 m.y. record of incision into cover strata overlying the Colorado Plateau and adjacent regions
Geosphere (Boulder, CO) (October 2015) 11 (6): 1719-1748

Abstract

New detrital zircon U-Pb age distributions from 49 late Cenozoic sandstones and Holocene sands (49 samples, n = 3922) record the arrival of extra-regional early Pliocene Colorado River sediment at Grand Wash (western USA) and downstream locations ca. 5.3 Ma and the subsequent evolution of the river's provenance signature. We define reference age distributions for the early Pliocene Colorado River (n = 559) and Holocene Colorado River (n = 601). The early Pliocene river is distinguished from the Holocene river by (1) a higher proportion of Yavapai-Mazatzal zircon derived from Rocky Mountain basement uplifts relative to Grenville zircon from Mesozoic supracrustal rocks, and (2) distinctive ( approximately 6%) late Eocene-Oligocene (40-23 Ma) zircon reworked from Cenozoic basins and volcanic fields in the southern Rocky Mountains and/or the eastern Green River catchment. Geologic relationships and interpretation of 135 published detrital zircon age distributions throughout the Colorado River catchment provide the interpretative basis for modeling evolution of the provenance signature. Mixture modeling based upon a modified formulation of the Kolmogorov-Smirnov statistic indicate a subtle yet robust change in Colorado River provenance signature over the past 5 m.y. During this interval the contribution from Cenozoic strata decreased from approximately 75% to 50% while pre-Cretaceous strata increased from approximately 25% to 50%. We interpret this change to reflect progressive erosional incision into plateau cover strata. Our finding is consistent with geologic and thermochronologic studies that indicate that maximum post-10 Ma erosion of the Colorado River catchment was concentrated across the eastern Utah-western Colorado region.


EISSN: 1553-040X
Serial Title: Geosphere (Boulder, CO)
Serial Volume: 11
Serial Issue: 6
Title: Detrital zircon U-Pb provenance of the Colorado River; a 5 m.y. record of incision into cover strata overlying the Colorado Plateau and adjacent regions
Affiliation: San Diego State University, Department of Geological Sciences, San Diego, CA, United States
Pages: 1719-1748
Published: 20151002
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 122
Accession Number: 2015-104838
Categories: StratigraphyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, geol. sketch map
N30°00'00" - N45°00'00", W115°00'00" - W105°00'00"
Secondary Affiliation: Stanford University, USA, United StatesUniversity of Arizona, USA, United StatesUniversity of Oregon, USA, United StatesU. S. Geological Survey, USA, United StatesUniversity of California, Los Angeles, USA, United StatesColorado Mesa University, USA, United StatesArizona Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201545
Program Name: USGSOPNon-USGS publications with USGS authors
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