Eocene–Recent drainage evolution of the Colorado River and its precursor: an integrated provenance perspective from SW California
Published:December 02, 2019
Uisdean Nicholson, Andrew Carter, Paula Robinson, David I. M. Macdonald, 2019. "Eocene–Recent drainage evolution of the Colorado River and its precursor: an integrated provenance perspective from SW California", River to Reservoir: Geoscience to Engineering, P. W. M. Corbett, A. Owen, A. J. Hartley, S. Pla-Pueyo, D. Barreto, C. Hackney, S. J. Kape
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The Colorado River in the SW of the USA is one of Earth's few continental-scale rivers with an active margin delta. Deformation along this transform margin, as well as associated intra-plate strain, has resulted in significant changes in sediment routing from the continental interior and post-depositional translation of older deltaic units. The oldest candidate deposits, fluvial sandstones of the Eocene Sespe Group, are now exposed in the Santa Monica Mountains, 300 km to the north of the Colorado River. Heavy mineral data from this basin indicate that sediment was sourced by a large river system, with some affinity to the early Pliocene Colorado River, but was unlikely to have been integrated across the Colorado Plateau. Sedimentological and mineralogical evidence from the earliest (c. 5.3 Ma) unequivocal Colorado River-derived sediments in the Salton Trough provide evidence for a rapid transition from locally derived sedimentation. Lack of evidence for a precursor phase of suspended-load sediment suggests that drainage capture took place in a proximal position, favouring a ‘top-down’ process of lake spillover. Following drainage integration, significant changes in heavy mineral assemblages of fluvio-deltaic sediments, particularly evident from apatite–tourmaline and garnet–zircon indices, as well as U–Pb ages of detrital zircons, document the integration of the fluvial system to its present form and progressive incision of the Colorado Plateau from the Miocene to the present.
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River to Reservoir: Geoscience to Engineering
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This volume brings together a number of papers from two workshops with the theme, ‘Rain, Rivers, Reservoirs’, which considered the dynamic changes to river systems as part of natural processes, particularly changing climatic conditions. Bringing researchers from two different locations to Brazil and the UK allowed scientists to contribute to and promote, ‘debate on current research…on how the planet works and how we can live sustainably on it’. This volume features a series of papers on the geoscience of modern and ancient rivers from across the world (Brazil, United States, Spain, Argentina, Canada, India and the UK), their evolution through time, their management, their deposits and their engineering, with both subsurface aquifers/hydrocarbon reservoirs (of Carboniferous, Triassic and Cretaceous age) and surface reservoirs considered.