Geologic map of the Castle Rock 7.5' quadrangle, Arizona and California

House, P. Kyle; John, Barbara E.; Malmon, Daniel V.; Block, Debra L.; Beard, Les P.; Felger, Tracey J.; Crow, Ryan S.; Schwing, Jonathan E.; Cassidy, Colleen E.

doi:10.3133/sim3411

Cited by 2 publications

(3 citation statements)

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“…Multiple post-Bullhead deposits (e.g., House, 2016;Crow et al, 2018a;House et al, 2018) have been identified in the lower Colorado River corridor ( Fig. 3).…”

Section: ■ Background Lower Colorado River Evolution and Depositsmentioning

confidence: 99%

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

et al. 2019

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The spatial and temporal distribution of Pliocene to Holocene Colorado River deposits (southwestern USA and northwestern Mexico) form a primary data set that records the evolution of a continental-scale river system and helps to delineate and quantify the magnitude of regional deformation. We focus in particular on the age and distribution of ancestral Colorado River deposits from field observations, geologic mapping, and subsurface studies in the area downstream from Grand Canyon (Arizona, USA). A new 4.73 ± 0.17 Ma age is reported for a basalt that flowed down Grand Wash to near its confluence with the Colorado River at the eastern end of what is now Lake Mead (Arizona and Nevada). That basalt flow, which caps tributary gravels, another previously dated 4.49 ± 0.46 Ma basalt flow that caps Colorado River gravel nearby, and previously dated speleothems (2.17 ± 0.34 and 3.87 ± 0.1 Ma) in western Grand Canyon allow for the calculation of long-term incision rates. Those rates are ∼90 m/Ma in western Grand Canyon and ∼18–64 m/Ma in the eastern Lake Mead area. In western Lake Mead and downstream, the base of 4.5–3.5 Ma ancestral Colorado River deposits, called the Bullhead Alluvium, is generally preserved below river level, suggesting little if any bedrock incision since deposition. Paleoprofiles reconstructed using ancestral river deposits indicate that the lower Colorado River established a smooth profile that has been graded to near sea level since ca. 4.5 Ma. Steady incision rates in western Grand Canyon over the past 0.6–4 Ma also suggest that the lower Colorado River has remained in a quasi–steady state for millions of years with respect to bedrock incision. Differential incision between the lower Colorado River corridor and western Grand Canyon is best explained by differential uplift across the Lake Mead region, as the overall 4.5 Ma profile of the Colorado River remains graded to Pliocene sea level, suggesting little regional subsidence or uplift. Cumulative estimates of ca. 4 Ma offsets across faults in the Lake Mead region are similar in magnitude to the differential incision across the area during the same approximate time frame. This suggests that in the past ∼4 Ma, vertical deformation in the Lake Mead area has been localized along faults, which may be a surficial response to more deep-seated processes. Together these data sets suggest ∼140–370 m of uplift in the past 2–4 Ma across the Lake Mead region.

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“…Multiple post-Bullhead deposits (e.g., House, 2016;Crow et al, 2018a;House et al, 2018) have been identified in the lower Colorado River corridor ( Fig. 3).…”

Section: ■ Background Lower Colorado River Evolution and Depositsmentioning

confidence: 99%

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

et al. 2019

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“…The largest of these water bodies, which occupied the Blythe basin and adjacent areas, covered over 10 000 km 2 (Spencer et al, 2013), almost twice the size Figure 1. Simplified stratigraphic and geomorphic relationships of Neogene formations exposed in the lower Colorado River basin (after Buising, 1990;Howard et al, 2015;Crow et al, 2019a). Ages for the Palo Verde alluvium (Late Pleistocene; Lundstrom et al, 2008) and the Riverside alluvium (Early(?)…”

Section: Introductionmentioning

confidence: 99%

“…In addition to this enigmatic history, the Bouse Formation, as well as the alluvial deposits that overlie it (e.g., Bullhead Alluvium, Howard et al, 2015;Chemehuevi Formation, Malmon et al, 2011;and Blythe Alluvium, Block et al, 2019; Fig. 1), house an outstanding and largely still untapped record of the history of both the CR since the Pliocene and climatic conditions during the early Pliocene.…”

Section: Introductionmentioning

confidence: 99%

The Bouse Formation, a controversial Neogene archive of the evolving Colorado River: a scientific drilling workshop report (28 February–3 March 2019 – BlueWater Resort & Casino, Parker, AZ, USA)

et al. 2019

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Neogene deposits of the lower Colorado River valley, especially the Miocene(?) and early Pliocene Bouse Formation, have been the focus of intense debate regarding the early paleoenvironmental history of this important continental-scale river system in southwestern North America and its integration with the proto-Gulf of California. Fine-grained units within these Neogene deposits also hold a promising archive of Pliocene paleoclimate history for this part of the world. Because the depocenter deposits of the Bouse Formation and the deposits that overlie and underlie it are poorly exposed and highly weathered, the formation is ripe for study through collection of drill cores. A workshop was held 28 February-3 March 2019 in Parker, AZ, USA, to discuss how scientific drilling might be employed to help resolve the Bouse controversies and improve our understanding of paleoclimate history in the region.Published by Copernicus Publications on behalf of the IODP and the ICDP.

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Geologic map of the Castle Rock 7.5' quadrangle, Arizona and California

Cited by 2 publications

References 5 publications

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

The Bouse Formation, a controversial Neogene archive of the evolving Colorado River: a scientific drilling workshop report (28 February–3 March 2019 – BlueWater Resort & Casino, Parker, AZ, USA)

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Geologic map of the Castle Rock 7.5' quadrangle, Arizona and California

Cited by 2 publications

References 5 publications

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River

The Bouse Formation, a controversial Neogene archive of the evolving Colorado River: a scientific drilling workshop report (28 February–3 March 2019 – BlueWater Resort &amp; Casino, Parker, AZ, USA)

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The Bouse Formation, a controversial Neogene archive of the evolving Colorado River: a scientific drilling workshop report (28 February–3 March 2019 – BlueWater Resort & Casino, Parker, AZ, USA)