Landscape inheritance and the pediment problem in the Mojave Desert of southern California

Oberlander, Theodore M.

doi:10.2475/ajs.274.8.849

Cited by 48 publications

(32 citation statements)

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“…Furthermore, we propose that the accordant summits and deeply weathered bedrock plateaus within the ECSZ are all that remains of a Mojave-wide erosion surface. This surface may be correlative with the pre-late Miocene surfaces documented in the western MDB and eastern Mojave Desert by Oberlander [1974] and by Dohrenwend et al [1987] and Miller [1995], respectively. This surface was and continues to be significantly disrupted by faulting and strain associated within the Eastern California Shear Zone.…”

Section: Two Groups Of Transtensional Basinssupporting

confidence: 77%

“…We also speculate that fractal by definition [Mandelbrot, 1983]. In contrast, active this surface may been part of a single or series of Mojave-wide faulting tends to produce landform shapes that are not statisti-erosion surface(s) that included the areas of the western Mojave cally distributed, as are fractals, but are instead stochastic, Desert block documented by Oberlander [1974] 4. Although the ECSZ has had a major impact on the surface of the MDB, tectonism can only directly account for a portion of the topography.…”

Section: Two Groups Of Transtensional Basinsmentioning

confidence: 86%

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Topographic effects of the Eastern California Shear Zone in the Mojave Desert

Dokka¹,

Macaluso²

2001

J. Geophys. Res.

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Abstract. Digital elevation data were used to evaluate the topographic implications of the late Neogene Eastern California Shear Zone (ECSZ). Analysis shows that the ECSZ has directly affected >18% of the surface of the Mojave Desert block (MDB); uncertainties regarding the distribution of strain in basins suggest that the area of effect may be larger by perhaps a factor of 2. Remaining areas are likely due to Quaternary erosion or are inherited from pre-ECSZ times. Major drainages and basins of the MDB are developed along transtensional depressions within the ECSZ. These depressions established the regional and local base levels that have governed erosion by running water. Local topography is closely tied to the style of strain. Highlands of the MDB are spatially associated with (1) areas that have or are currently undergoing contractional strain associated with transpression within the ECSZ and (2) areas that lie adjacent to uplifted transpressional belts that bound the Mojave Desert (San Bernardino and San Gabriel Mountains). In contrast, lowland areas are spatially associated only with transtensional areas within the ECSZ. Examination of the topography in the transtensional areas also reveals two, distinct populations of elevation. Spatial analysis indicates that areas that have undergone the greatest local transtension associated with dextral shear are also the lowest topographically. These areas formed during the earliest phase of movement of the ECSZ (late Miocene to early Pleistocene). The second population is coextensive with recently formed transtensional basins that continue to be active.

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Section: Two Groups Of Transtensional Basinssupporting

confidence: 77%

Section: Two Groups Of Transtensional Basinsmentioning

confidence: 86%

Topographic effects of the Eastern California Shear Zone in the Mojave Desert

Dokka¹,

Macaluso²

2001

J. Geophys. Res.

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“…Xenoliths are found here in basaltic rocks ranging in age from 0.01 to 9.2 m.y. (Oberlander, 1974;Dohrenwend and others, 1984).…”

Section: Distribution and Settingmentioning

confidence: 99%

Mafic and ultramafic xenoliths from volcanic rocks of the western United States

Wilshire¹,

Meyer²,

Nakata³

et al. 1985

Open-File Report

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“…Granitic pediments typically are moderately weathered and a regime of chemical weathering seems required for active pediplanation on granitic or crystalline bedrock. Indeed, Oberlander (1974) argued that the granitic pediment landforms of the Mojave Desert in California are inherited features that formed through rapid chemical breakdown of granitic rock and backwearing under a more humid climate during the Tertiary.…”

Section: B Braidplain Depositionmentioning

confidence: 99%

“…The Lewisian palaeoplain shows no evidence for the former presence of a thick regolith like the deep (120+ m) weathering on granite in peneplaned regions (Ollier, 1965). However, analogues of the palaeoplain may occur in mountainous, now semi-arid regions, where uplands commonly are bordered by piedmont plains whose upper parts comprise an eroded bedrock surface of low relief, or pediment, that slopes gently away from the uplands (Tuan, 1959;Oberlander, 1974Oberlander, , 1997. The basinward part of a pediment that is buried by piedmont alluvium is termed a suballuvial bench.…”

Section: B Braidplain Depositionmentioning

confidence: 99%

Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance

Williams

2001

Geol. Mag.

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The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in north-west Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising > 2650 measurements on trough cross-bedding are of low variability and show overall eastward flow. The projection upcurrent of regionally divergent flow directions for the lower part of the member indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian) normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in two main stages. Uplift of a western source area by movement on basin-bounding normal faults occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring further to the west and south along the line of the Minch Fault. The bulk of the Applecross Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental margins of the North Atlantic. The tectonic events may mark an early phase in the crustal extension that led ultimately to the opening of the Iapetus ocean.

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Landscape inheritance and the pediment problem in the Mojave Desert of southern California

Cited by 48 publications

References 0 publications

Topographic effects of the Eastern California Shear Zone in the Mojave Desert

Topographic effects of the Eastern California Shear Zone in the Mojave Desert

Mafic and ultramafic xenoliths from volcanic rocks of the western United States

Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance

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