Quaternary geology of the Basin and Range Province in California

Dohrenwend, J.C.; Bull, William B.; McFadden, Leslie D.; Smith, George I.; Smith, Russell C.; Wells, Stephen

doi:10.1130/dnag-gna-k2.321

Cited by 7 publications

(7 citation statements)

References 128 publications

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“…The 754 ± 4 ka isochron age from the first basalt flow yielded an unacceptable mean square of weighted deviates value (MSWD = 15), and thus the average of 770 ± 40 ka from the last three heating steps, accounting for 92.8% of the 39 Ar K released gas, best represents its age. These ages are slightly older than a K-Ar age of $600 ka cited by Dohrenwend et al [1991]. The age difference cannot be evaluated because which flow was dated via the K-Ar method and the error in this age are not available (B.…”

Section: Age Of the Pipkin Basaltmentioning

confidence: 89%

“…(1) Maximum total offset on a single fault strand, including a component of distributed strain, is well documented here [ Dokka , 1983; Garfunkel , 1974]. (2) The Pipkin basalt flow of Quaternary age [ Dohrenwend et al , 1991] lies adjacent to and is truncated by the fault, providing a distinctive clast source and, potentially, a readily datable offset marker. (3) Steep channels draining the Rodman Mountains on the southeast side of the fault provide abundant coarse‐grained sediment to alluvial fans deposited across the fault.…”

Section: Neotectonic Mappingmentioning

confidence: 99%

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Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone

et al. 2007

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[1] Long-term (10 5 years) fault slip rates test the scale of discrepancy between infrequent paleoseismicity and relatively rapid geodetic rates of dextral shear in the Eastern California Shear Zone (ECSZ). The Calico fault is one of a family of dextral faults that traverse the Mojave Desert portion of the ECSZ. Its slip rate is determined from matching and dating incised Pleistocene alluvial fan deposits and surfaces displaced by fault slip. A high-resolution topographic base acquired via airborne laser swath mapping aids in identification and mapping of deformed geomorphic features. The oldest geomorphically preserved alluvial fan, unit B, is displaced 900 ± 200 m from its source at Sheep Springs Wash in the northern Rodman Mountains. This fan deposit contains the first preserved occurrence of basalt clasts derived from the Pipkin lava field and overlies Quaternary conglomerate deposits lacking these clasts. The 40 Ar/ 39 Ar dating of two flows from this field yields consistent ages of 770 ± 40 ka and 735 ± 9 ka. An age of 650 ± 100 ka is assigned to this fan deposit based on these ages and on the oldest cosmogenic 3 He exposure date of 653 ± 20 ka on a basalt boulder from the surface of unit B. This assigned age and offset together yield a mid-Pleistocene to present average slip rate of 1.4 ± 0.4 mm/yr. A younger fan surface, unit K, records 100 ± 10 m of dextral displacement and preserves original depositional morphology of its surface. Granitic boulders and pavement samples from this surface yield an average age of 56.4 ± 7.7 ka after taking into account minimal cosmogenic inheritance of granitic clasts. The displaced and dated K fans yield a slip rate of 1.8 ± 0.3 mm/yr. Distributed deformation of the region surrounding the fault trace, if active, could increase the overall displacement rate to 2.1 ± 0.5 mm/yr. Acceleration of slip rate from an average of 1.4 mm/yr prior to $50 ka to 1.8 mm/yr since $50 ka is possible, though a single time-averaged slip rate of 1.6 ± 0.2 mm/yr satisfies the data. These rates are faster than any other paleoseismic or long-term slip rate yet determined for other dextral faults in the Mojave Desert and imply that fault slip rates and earthquake productivity are heterogeneous across this portion of the ECSZ. Total displacement across the Calico fault diminishes northward as shear is distributed into folding and sinistral faults in the Calico Mountains. This pattern is consistent with an approximately threefold drop in geologic slip rate as the Calico fault steps over onto the Blackwater fault and demonstrates the significance of fault interaction for understanding the pattern of present-day strain accumulation in the ECSZ.

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Section: Age Of the Pipkin Basaltmentioning

confidence: 89%

Section: Neotectonic Mappingmentioning

confidence: 99%

Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone

et al. 2007

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“…Well-developed desert pavements and darkly varnished pebbles and cobbles cover parts of the fans, indicating that some surfaces are stable over time periods in excess of several thousand years. Fan deposits in Yuma Wash are believed to correlate with middle to late Pleistocene surfaces found elsewhere in the region (Dohrenwend et al, 1991), although no numerical chronology has been established, and no 14 C datable material was found during this study. Some of the fan deposits appear to have been tilted and beveled, suggesting that they might be much older.…”

Section: Geomorphic Settingmentioning

confidence: 89%

Using 10Be and 26Al to determine sediment generation rates and identify sediment source areas in an arid region drainage basin

2002

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We measured 10 Be and 26 Al in 64 sediment and bedrock samples collected throughout the arid, 187 km 2 Yuma Wash drainage basin, southwestern Arizona. From the measurements, we determine long-term, time-integrated rates of upland sediment generation (81 F 5 g m À 2 year) and bedrock equivalent lowering (30 F 2 m Ma À 1 ) consistent with other estimates for regions of similar climate, lithology, and topography. In a small ( f 8 km 2 ), upland sub-basin, differences in nuclide concentrations between bedrock outcrops and hillslope colluvium suggest weathering of bedrock beneath a colluvial cover is a more significant source of sediment (40 Â 10 4 kg year) than weathering of exposed bedrock surfaces (10 Â 10 4 kg year). Mixing models constructed from nuclide concentrations of sediment reservoirs identify important sediment source areas. Hillslope colluvium is the dominant sediment source to the upper reaches of the sub-basin channel; channel cutting of alluvial terraces is the dominant source in the lower reaches. Similarities in nuclide concentrations of various sediment reservoirs indicate short sediment storage times ( < 10 3 years). Nuclide concentrations, measured in channel sediment from tributaries of Yuma Wash and in samples collected along the length of the Wash, were used to construct mixing models and determine sediment sources to the main stem channel. We find an exponential decrease in the channel nuclide concentrations with distance downstream, suggesting that as much as 40% of sediment discharged from Yuma Wash has been recycled from storage within basin fill alluvium. Sediment generation and denudation rates determined from the main stem are greater (25%) than rates determined from upland sub-basins suggesting that, currently, sediment may be exported from the basin more quickly than it is being generated in the uplands. Independence of nuclide concentration and sediment grain size indicates that channels transport sediment in discrete pulses before rapidly depositing poorly sorted material, suggesting that differences in transport times for different size materials are minimal. D

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“…The Manix Basin in the Mojave Desert of south-eastern California is the site of ancient Lake Manix (Buwalda, 1914;Meek, 1989Meek, , 1990Dohrenwend et al, 1991). Far from being a unique geological setting, the fine-grained lacustrine sediments in the Basin are part of the Pleistocene legacy shared by depressions throughout the entire Basin and Range and Mojave provinces (Smith & Street-Perrott, 1983).…”

Section: Introductionmentioning

confidence: 96%

Degradation of sandy arid shrubland environments: observations, process modelling, and management implications

Okin

Murray

Schlesinger

2001

Journal of Arid Environments

169

108

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Quaternary geology of the Basin and Range Province in California

Cited by 7 publications

References 128 publications

Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone

Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone

Using 10Be and 26Al to determine sediment generation rates and identify sediment source areas in an arid region drainage basin

Degradation of sandy arid shrubland environments: observations, process modelling, and management implications

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