scholarly journals Evaluating the Shinumo-Sespe drainage connection: Arguments against the “old” (70–17 Ma) Grand Canyon models for Colorado Plateau drainage evolution

Geosphere ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1425-1456
Author(s):  
Karl E. Karlstrom ◽  
Carl E. Jacobson ◽  
Kurt E. Sundell ◽  
Athena Eyster ◽  
Ron Blakey ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Gulf Of California ◽  
Colorado Plateau ◽  
Grand Canyon ◽  
River System ◽  
Death Valley ◽  
Transverse Ranges ◽  
Drainage Connection ◽  
The Pacific ◽  
History Of

Abstract The provocative hypothesis that the Shinumo Sandstone in the depths of Grand Canyon was the source for clasts of orthoquartzite in conglomerate of the Sespe Formation of coastal California, if verified, would indicate that a major river system flowed southwest from the Colorado Plateau to the Pacific Ocean prior to opening of the Gulf of California, and would imply that Grand Canyon had been carved to within a few hundred meters of its modern depth at the time of this drainage connection. The proposed Eocene Shinumo-Sespe connection, however, is not supported by detrital zircon nor paleomagnetic-inclination data and is refuted by thermochronology that shows that the Shinumo Sandstone of eastern Grand Canyon was >60 °C (∼1.8 km deep) and hence not incised at this time. A proposed 20 Ma (Miocene) Shinumo-Sespe drainage connection based on clasts in the Sespe Formation is also refuted. We point out numerous caveats and non-unique interpretations of paleomagnetic data from clasts. Further, our detrital zircon analysis requires diverse sources for Sespe clasts, with better statistical matches for the four “most-Shinumo-like” Sespe clasts with quartzites of the Big Bear Group and Ontario Ridge metasedimentary succession of the Transverse Ranges, Horse Thief Springs Formation from Death Valley, and Troy Quartzite of central Arizona. Diverse thermochronologic and geologic data also refute a Miocene river pathway through western Grand Canyon and Grand Wash trough. Thus, Sespe clasts do not require a drainage connection from Grand Canyon or the Colorado Plateau and provide no constraints for the history of carving of Grand Canyon. Instead, abundant evidence refutes the “old” (70–17 Ma) Grand Canyon models and supports a <6 Ma Grand Canyon.

scholarly journals Supplemental Material: Evaluating the Shinumo-Sespe drainage connection: Arguments against the “old” (70–17 Ma) Grand Canyon models for Colorado Plateau drainage evolution

2020 ◽  
Author(s):  
K.E. Karlstrom ◽  
et al.
Keyword(s):  
Detrital Zircon ◽  
Colorado Plateau ◽  
Grand Canyon ◽  
Quantitative Comparison ◽  
Cross Bedding ◽  
Drainage Connection ◽  
Comparison Results

Table S1: Rotations of measured paleomagnetic paleopoles to test the error introduced by measuring inclinations relative to cross bedding of different orientations instead of horizontal bedding. Table S2: Detrital zircon data used in this study. Table S3: Quantitative comparison results from DZstats.

scholarly journals Supplemental Material: Evaluating the Shinumo-Sespe drainage connection: Arguments against the “old” (70–17 Ma) Grand Canyon models for Colorado Plateau drainage evolution

2020 ◽  
Author(s):  
K.E. Karlstrom ◽  
et al.
Keyword(s):  
Detrital Zircon ◽  
Colorado Plateau ◽  
Grand Canyon ◽  
Quantitative Comparison ◽  
Cross Bedding ◽  
Drainage Connection ◽  
Comparison Results

Table S1: Rotations of measured paleomagnetic paleopoles to test the error introduced by measuring inclinations relative to cross bedding of different orientations instead of horizontal bedding. Table S2: Detrital zircon data used in this study. Table S3: Quantitative comparison results from DZstats.

scholarly journals A constraint on post–6 Ma timing of western Grand Canyon (Arizona, USA) incision removed: Local derivation indicated by ca. 5.4 Ma fluvial deposits below Shivwits Plateau basalts north of Grand Canyon

Geosphere ◽  
2021 ◽  
Author(s):  
A.T. Steelquist ◽  
G.E. Hilley ◽  
I. Lucchitta ◽  
R.A. Young
Keyword(s):  
United States ◽  
Detrital Zircon ◽  
Colorado River ◽  
Landscape Evolution ◽  
Colorado Plateau ◽  
Grand Canyon ◽  
River System ◽  
Fluvial Deposits ◽  
Western Colorado ◽  
Rule Out

The timing of integration of the Colorado River system is central to understanding the landscape evolution of much of the southwestern United States. However, the time at which the Colorado River started incising the westernmost Grand Canyon (Arizona) is still an unsettled question, with conflicting interpretations of both geologic and thermochronologic data from western Grand Canyon. Fluvial gravels on the Shivwits Plateau, north of the canyon, have been reported to contain clasts derived from south of the modern canyon, suggesting the absence of western Grand Canyon at the time of their deposition. In this study, we reassess these deposits using modern geochronologic measurements to determine the age of the deposits and the presence or absence of clasts from south of the Grand Canyon. We could not identify southerly derived clasts, so cannot rule out the existence of a major topographic barrier such as Grand Canyon prior to the age of deposition of the gravels. 40Ar/39Ar analysis of a basalt clast entrained in the upper deposit (in combination with prior data) supports a maximum age of deposition of ca. 5.4 Ma, limiting deposition to post-Miocene, a period from which very few diagnostic and dated fluvial deposits remain in the western Colorado Plateau. Analysis of detrital zircon composition of the sand matrix supports interpretation of the deposit as being locally derived and not part of a major throughgoing river. We suggest that the published constraint of <6 Ma timing of Grand Canyon incision may be removed, given that no clasts that must be sourced from south of Grand Canyon were found in the only known outcrop of gravels under the Shivwits Plateau basalts at Grassy Mountain north of Grand Canyon.

scholarly journals CRUSTACEOS DECAPODOS DEL PACIFICO COLOMBIANO: LISTA DE ESPECIES Y CONSIDERACIONES ZOOGEOGRAFICAS

2016 ◽  
Vol 21 ◽  
Author(s):  
Rafael Lemaitre ◽  
Ricardo Alvarez León
Keyword(s):  
Gulf Of California ◽  
Pacific Coast ◽  
Marine Species ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Review Of The Literature ◽  
Tropical Eastern Pacific ◽  
The Pacific ◽  
History Of ◽  
The Caribbean

The Pacific coast of Colombia has been poorly explored, and its fauna is one of the least known in the tropical eastern Pacific. Although knowledge of the decapod fauna from this coast has recently increased, the information is scattered in numerous sources. A review of the literature showed that 378 decapods have been reported from this coast, including the islands of Gorgona and Malpelo. The numbers of species are distributed as follows; Dendrobranchiata, 18; Caridea,79; Thalassinidea, 13; Palinura, 6; Anomura, 61; and Brachyura, 201 .Twenty-seven species are known exclusively from the Colombian coast, three of which are endemic to the islands of Malpelo or Gorgona. A list of nominal species is presented, including information on distribution, important references, and synonyms under which the taxa have been reported for this coast. A summary of the history of explorations of the Pacific coast of Colombia as it relates to decapods, is presented. Zoogeographic affinities are briefly discussed for the marine species based on published distributions. Affinities are greatest with the Gulf of California (51.8%), followed by the Galápagos (28.6%), the Indo-Pacific (8.8%), and the Caribbean- Atlantic (7.7%).

scholarly journals 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)

2019 ◽  
Vol 26 ◽  
pp. 59-67
Author(s):  
Andrew Cohen ◽  
Colleen Cassidy ◽  
Ryan Crow ◽  
Jordon Bright ◽  
Laura Crossey ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Colorado River ◽  
River System ◽  
Workshop Report ◽  
Scientific Drilling ◽  
Fine Grained ◽  
Continental Scale ◽  
The World ◽  
History Of ◽  
Intense Debate

Abstract. 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.

scholarly journals Cenozoic incision history of the Little Colorado River: Its role in carving Grand Canyon and onset of rapid incision in the past ca. 2 Ma in the Colorado River System

Geosphere ◽  
2016 ◽  
Vol 13 (1) ◽  
pp. 49-81 ◽  
Author(s):  
K.E. Karlstrom ◽  
L.J. Crossey ◽  
E. Embid ◽  
R. Crow ◽  
M. Heizler ◽  
...  
Keyword(s):  
Colorado River ◽  
Grand Canyon ◽  
River System ◽  
The Past ◽  
History Of

The Mammals

2002 ◽  
Author(s):  
Timothy E. Lawlor ◽  
David J. Hajher
Keyword(s):  
Gulf Of California ◽  
Human Impacts ◽  
Oceanic Islands ◽  
Mammalian Fauna ◽  
San Jose ◽  
Ecological Processes ◽  
The Pacific ◽  
History Of ◽  
Sea Of Cortes ◽  
Sea Of Cortez

In The Log of the Sea of Cortez, that memorable treatise of science, adventure, and philosophy, John Steinbeck (1951) made bare mention of mammals. Of course, the main purpose of that effort was to chronicle a trip to the Gulf of California to collect invertebrates in the company of Steinbeck’s friend and scientist, Ed Ricketts. The party visited four islands—Tiburón, Coronados, San José, and Espíritu Santo. At anchor off Isla Tiburόn, Steinbeck reported a swarm of bats that approached their boat. One bat was collected but, to the best of our knowledge, it was never identified or preserved. Aside from some descriptions of taxa (e.g., Butt 1932), relatively little was known at the time about mammals from islands in the Sea of Cortés. There is now a reasonably rich history of systematic and biogeographic studies of mammals in and adjacent to the Sea of Cortés (for general reviews, see Orr 1960; Huey 1964; Lawlor 1983; and Hafner and Riddle 1997). Here we summarize much of that information and explore biogeographic patterns that emerge from it, add important recent records of bats, and evaluate new evidence about the origins of insular faunas and the ecological processes and human impacts that affect colonization and persistence of mammals on gulf islands. The terrestrial mammalian fauna of islands in the Sea of Cortés (including islands off the Pacific coast of Baja California) comprises 45 species, of which 18 currently are recognized as endemics (but see below), representing 5 orders, 9 families, and 14 genera (app. 12.1). Collectively they share relationships with mainland representatives on both sides of the gulf and are divisible into 28 clades of species or species groups (app. 12.2). Rodents are disproportionately represented, constituting a total of 35 species and 76 of 97 total insular occurrences, and they are the only nonvolant mammals to become established on distant oceanic islands. In addition, except for the few species of lagomorphs, which occur only on landbridge islands, a greater proportion of mainland species of rodents occurs on islands than is the case for other groups of mammals.

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