The eastern boundary of the Eastern California shear zone (ECSZ) is defined by the Stateline-Amar... more The eastern boundary of the Eastern California shear zone (ECSZ) is defined by the Stateline-Amargosa Valley fault zone (SAVFZ), a NW striking zone of dextral faulting that extends 150 km along the CA-NV border in Clark and Nye counties. This fault system has accumulated ~ 30 km of slip since 12.5 Ma, yielding a long-term slip rate of ~ 2
A short-baseline network that we have established at Yucca Mountain, southern Nevada, is enabling... more A short-baseline network that we have established at Yucca Mountain, southern Nevada, is enabling us to put new constraints on the level at which individual site motion can be detected by continuous GPS stations. We use this network to investigate and quantify aspects of the GPS error budget at a level of precision that would have been hard to imagine
Understanding the paleoelevation history of orogens is fundamental to answering a number of signi... more Understanding the paleoelevation history of orogens is fundamental to answering a number of significant questions about continental deformation. Most paleoaltimeters rely on proxies for measuring paleoelevation that may be affected by factors other than elevation, such as climate. The basalt vesicle paleoaltimeter avoids problems associated with such proxies by directly measuring the paleo-atmospheric pressure recorded by vesicle size-distributions in basalt
A fundamental issue in continental dynamics is whether deformation within the broad Pacific-North... more A fundamental issue in continental dynamics is whether deformation within the broad Pacific-North America plate boundary in the southwestern United States is better described by the relative motions of rigid microplates or by diffuse crustal flow. Whereas the Colorado Plateau and Sierra Nevada-Great Valley regions appear to be fairly undeformed over geological time scales, crustal extension between these regions in the Basin and Range province based on prevalent Quaternary faulting appears to have been relatively homogeneous. However, historic seismicity, which is largely confined within the relatively narrow Central Nevada Seismic Belt (CNSB) and the Intermountain Seismic Belt (ISB), may suggest that modern deformation of the Basin and Range province is also confined to these province bounding belts and that the central part of the Basin and Range province, the Central Great Basin region, is presently relatively rigid. We use site velocities from several campaign and continuous GPS...
The ongoing Arabian-Eurasian collision provides an opportunity to understand strain localization ... more The ongoing Arabian-Eurasian collision provides an opportunity to understand strain localization within a nascent orogen. The central third of this collision lies between the Black and Caspian Seas, with late Cenozic deformation extending over 700 km across strike, from the Zagros in the south to the Greater Caucasus (GC) in the north. The GC range is flanked to the south
New field observations from the Gonga Shan (7756m) region in eastern Tibet show a spatial associa... more New field observations from the Gonga Shan (7756m) region in eastern Tibet show a spatial association between high topography, intense erosion and exhumation and extensional faulting. The Gonga Shan massif is a region anomalously high topography, approximately 1 - 3 km in excess of the surrounding plateau elevations, and incised by rapid fluvial and glacial erosion. The massif is bounded
The successful quantification of long-term erosion rates underpins out understanding of landscape... more The successful quantification of long-term erosion rates underpins out understanding of landscape formation, the topographic evolution of mountain ranges, and the mass balance within active orogens. The measurement of in situ-produced cosmogenic radionuclides (CRNs) in fluvial and alluvial sediments is perhaps the method with the greatest ability to provide long-term erosion rates over a wide variety of landscapes and erosional
The Stateline fault zone is the easternmost active dextral structure in the Eastern California Sh... more The Stateline fault zone is the easternmost active dextral structure in the Eastern California Shear Zone and its northern segment lies only ~20 km southwest of the proposed Yucca Mountain nuclear waste repository. This ~150 km long fault zone follows the California-Nevada state line from Amargosa Valley to Ivanpah Valley. The geometry, kinematics, and displacement history of this structure are
ABSTRACT Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climat... more ABSTRACT Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climatic conditions and active tectonic processes. Spatial and temporal variations in erosion rates along strike are presumably controlled by differences in local climate, seismicity, deformation rates, and lithology. Quantifying the contribution of each of these parameters to the erosional budget of the Himalaya, however, is a nontrivial problem. The easternmost portion of the Himalayan arc offers a natural laboratory to explore the role of climatic influence on erosion rates. Deformation and uplift of the Shillong Plateau since ~8 Ma has created an orographic barrier ~400 km long that shields the eastern Himalaya, in Arunachal Pradesh, India, from a significant proportion of the precipitation carried by the South Asian Monsoon. Long-term exhumation rates derived from the Himalaya west and east of this orographic barrier have been shown to differ by a factor of ~2, a difference ascribed to reduced climatic forcing of erosion in the lee of the Shillong Plateau. Here we present apatite (U-Th)/He thermochronology data from modern detrital samples collected from northeast India. Between 18-20 single grain ages from each catchment were analyzed in order to calculate erosion rates on a 106 yr timescale. Recently developed Bayesian techniques for the inverse modeling of detrital data were used to derive time-temperature histories for each sample. Recent erosion rates modeled for a single south-facing catchment on the Shillong Plateau are modest, ~0.25 km Myr-1, and show a clear increase in exhumation rates at ~8 Ma from rates of
The eastern boundary of the Eastern California shear zone (ECSZ) is defined by the Stateline-Amar... more The eastern boundary of the Eastern California shear zone (ECSZ) is defined by the Stateline-Amargosa Valley fault zone (SAVFZ), a NW striking zone of dextral faulting that extends 150 km along the CA-NV border in Clark and Nye counties. This fault system has accumulated ~ 30 km of slip since 12.5 Ma, yielding a long-term slip rate of ~ 2
A short-baseline network that we have established at Yucca Mountain, southern Nevada, is enabling... more A short-baseline network that we have established at Yucca Mountain, southern Nevada, is enabling us to put new constraints on the level at which individual site motion can be detected by continuous GPS stations. We use this network to investigate and quantify aspects of the GPS error budget at a level of precision that would have been hard to imagine
Understanding the paleoelevation history of orogens is fundamental to answering a number of signi... more Understanding the paleoelevation history of orogens is fundamental to answering a number of significant questions about continental deformation. Most paleoaltimeters rely on proxies for measuring paleoelevation that may be affected by factors other than elevation, such as climate. The basalt vesicle paleoaltimeter avoids problems associated with such proxies by directly measuring the paleo-atmospheric pressure recorded by vesicle size-distributions in basalt
A fundamental issue in continental dynamics is whether deformation within the broad Pacific-North... more A fundamental issue in continental dynamics is whether deformation within the broad Pacific-North America plate boundary in the southwestern United States is better described by the relative motions of rigid microplates or by diffuse crustal flow. Whereas the Colorado Plateau and Sierra Nevada-Great Valley regions appear to be fairly undeformed over geological time scales, crustal extension between these regions in the Basin and Range province based on prevalent Quaternary faulting appears to have been relatively homogeneous. However, historic seismicity, which is largely confined within the relatively narrow Central Nevada Seismic Belt (CNSB) and the Intermountain Seismic Belt (ISB), may suggest that modern deformation of the Basin and Range province is also confined to these province bounding belts and that the central part of the Basin and Range province, the Central Great Basin region, is presently relatively rigid. We use site velocities from several campaign and continuous GPS...
The ongoing Arabian-Eurasian collision provides an opportunity to understand strain localization ... more The ongoing Arabian-Eurasian collision provides an opportunity to understand strain localization within a nascent orogen. The central third of this collision lies between the Black and Caspian Seas, with late Cenozic deformation extending over 700 km across strike, from the Zagros in the south to the Greater Caucasus (GC) in the north. The GC range is flanked to the south
New field observations from the Gonga Shan (7756m) region in eastern Tibet show a spatial associa... more New field observations from the Gonga Shan (7756m) region in eastern Tibet show a spatial association between high topography, intense erosion and exhumation and extensional faulting. The Gonga Shan massif is a region anomalously high topography, approximately 1 - 3 km in excess of the surrounding plateau elevations, and incised by rapid fluvial and glacial erosion. The massif is bounded
The successful quantification of long-term erosion rates underpins out understanding of landscape... more The successful quantification of long-term erosion rates underpins out understanding of landscape formation, the topographic evolution of mountain ranges, and the mass balance within active orogens. The measurement of in situ-produced cosmogenic radionuclides (CRNs) in fluvial and alluvial sediments is perhaps the method with the greatest ability to provide long-term erosion rates over a wide variety of landscapes and erosional
The Stateline fault zone is the easternmost active dextral structure in the Eastern California Sh... more The Stateline fault zone is the easternmost active dextral structure in the Eastern California Shear Zone and its northern segment lies only ~20 km southwest of the proposed Yucca Mountain nuclear waste repository. This ~150 km long fault zone follows the California-Nevada state line from Amargosa Valley to Ivanpah Valley. The geometry, kinematics, and displacement history of this structure are
ABSTRACT Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climat... more ABSTRACT Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climatic conditions and active tectonic processes. Spatial and temporal variations in erosion rates along strike are presumably controlled by differences in local climate, seismicity, deformation rates, and lithology. Quantifying the contribution of each of these parameters to the erosional budget of the Himalaya, however, is a nontrivial problem. The easternmost portion of the Himalayan arc offers a natural laboratory to explore the role of climatic influence on erosion rates. Deformation and uplift of the Shillong Plateau since ~8 Ma has created an orographic barrier ~400 km long that shields the eastern Himalaya, in Arunachal Pradesh, India, from a significant proportion of the precipitation carried by the South Asian Monsoon. Long-term exhumation rates derived from the Himalaya west and east of this orographic barrier have been shown to differ by a factor of ~2, a difference ascribed to reduced climatic forcing of erosion in the lee of the Shillong Plateau. Here we present apatite (U-Th)/He thermochronology data from modern detrital samples collected from northeast India. Between 18-20 single grain ages from each catchment were analyzed in order to calculate erosion rates on a 106 yr timescale. Recently developed Bayesian techniques for the inverse modeling of detrital data were used to derive time-temperature histories for each sample. Recent erosion rates modeled for a single south-facing catchment on the Shillong Plateau are modest, ~0.25 km Myr-1, and show a clear increase in exhumation rates at ~8 Ma from rates of
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