Douglas Burbank
University of California, Santa Barbara, Earth Science, Faculty Member
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Research Interests: Geology, Geomorphology, Tectonics, Geochronology, Geodynamics, and 15 moreMountain Building, Numerical Modelling, Multidisciplinary, Geomorphology and Active tectonics, Himalayas, Erosion, First-Order Logic, Glaciers, Erosion and climate, Finite Element Model, Geophysical, Late Quaternary, Friction Coefficient, Main Central Thrust, and Slip partitioning
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Research Interests: Geology, Geochemistry, Geophysics, Hydrology, Environment and natural resources conservation, and 14 moreEnvironmental Monitoring, Natural Resource Economics, Magnetostratigraphy, Basin analysis, Environmental Sciences, Hydraulic Engineering, Himalaya, Water resource management, Citation, Civil and Environmental Engineering, Foreland Basin, Siwaliks, Sustainability, and Fold and thrust belt
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As shown by previous studies of normal faults, the relationship of fault length to fault displacement provides insights into fault-growth history and processes. We focus on the fault length-displacement relationships of a thrust fault... more
As shown by previous studies of normal faults, the relationship of fault length to fault displacement provides insights into fault-growth history and processes. We focus on the fault length-displacement relationships of a thrust fault system. Although thrust faults are a fundamental part of deformation in compressional regimes, few studies of displacement scaling in active thrust systems have been undertaken. We have measured fault length and scarp height on over 30 segments of the Ostler fault zone on the eastern flank of the Southern Alps, New Zealand. The fault segments cut broad glacial outwash surfaces and fluvial terraces that provide a reference surface against which scarp height can be measured. Ground-penetrating radar investigations have been conducted to image the fault zone in the shallow subsurface (~10 m) and constrain the fault dip, allowing scarp height to be used as a proxy fault displacement. Fault length vs. displacement plots have been made for each segment and show a wide variety of shapes ranging from long, low-displacement scarps probably indicative of single earthquake ruptures on young surfaces, to well-developed bell-shaped profiles on older surfaces. To explain these patterns, we employ a simple conceptual model of fault propagation and displacement accumulation by successive seismic ruptures. We have also generated average displacement vs. fault length statistics for all segments for investigating fault-scaling relationships. Preliminary analysis shows a roughly linear average displacement vs. length scaling with displacement being 1-5% of fault length. In addition to fault length-displacement relationships, detailed geomorphic surveying has been conducted on the thrust deformation front. From these data we show that displacement magnitude and style change abruptly along-strike of the fault. These changing deformation modes may correlate with differing material properties in the faulted medium.
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10Be exposure ages of moraine boulders and glacially-carved bedrock walls in the Annapurna region of central Nepal show that small glaciers (<8 km2) were at their maximum extent during the Younger Dryas cold... more
10Be exposure ages of moraine boulders and glacially-carved bedrock walls in the Annapurna region of central Nepal show that small glaciers (<8 km2) were at their maximum extent during the Younger Dryas cold period. Preliminary dates from several large glaciers also show advances during the Younger Dryas. Analyses of past and present small glacier ELAs (equilibrium line altitudes) and modern
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Page 1. Evolution of latest CretaceousEocene nonmarine deposystems in the Axhandle piggyback basin of central Utah PJ Talling* University of Southern California, Los Angeles, California 90089-0740 TF Lawton New Mexico ...
We present a mechanical analysis of the problem of slip partitioning between the major thrust systems in a collisional range. We focus on two structures in the Himalayas of central Nepal: the Main Himalayan Thrust (MHT) and the Main... more
We present a mechanical analysis of the problem of slip partitioning between the major thrust systems in a collisional range. We focus on two structures in the Himalayas of central Nepal: the Main Himalayan Thrust (MHT) and the Main Central Thrust (MCT). We use finite element modeling to test the influence of various parameters, such as friction coefficients and surface processes, and we investigate how they affect the distribution of deformation between these two faults. We observe that reproduction of the late Quaternary kinematic pattern across the range with our model requires strict conditions on the friction coefficients, such that the MHT is very weak, whereas the MCT is significantly stronger. The most important parameter that controls slip partitioning appears to be the dip angle of the MCT, with a gentler or steeper MCT promoting or inhibiting slip, respectively. We also show that transient loading and unloading through focused glacial erosion in the higher part of the range can unclamp the MCT and allow a significant increase in slip rates. The results of this mechanical sensitivity investigation have important implications for the dynamics of the Himalayan wedge and point toward along-strike structural variations as a first-order control on slip partitioning.
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ABSTRACT deformation in three dimensions involves shortening, uplift, and lateral growth. Fluvial terraces represent strain markers that have been widely applied to constrain a fold's shortening and uplift. For the lateral growth,... more
ABSTRACT deformation in three dimensions involves shortening, uplift, and lateral growth. Fluvial terraces represent strain markers that have been widely applied to constrain a fold's shortening and uplift. For the lateral growth, however, the utility of fluvial terraces has been commonly ignored. Situated along northern margin of Chinese Pamir, the Mushi anticline preserves, along its northern flank, flights of passively deformed fluvial terraces that can be used to constrain three-dimensional folding history, especially lateral growth. The Mushi anticline is a geometrically simple fault-tip fold with a total shortening of 740 ± 110 m and rock uplift of ~1300 m. Geologic and geomorphic mapping and dGPS surveys reveal that terrace surfaces perpendicular to the fold's strike display increased rotation with age, implying the fold grows by progressive limb rotation. We use a pure-shear fault-tip fold model to estimate a uniform shortening rate of 1.5 + 1.3/-0.5 mm/a and a rock-uplift rate of 2.3 + 2.1/-0.8 mm/a. Parallel to the fold's strike, longitudinal profiles of terrace surfaces also display age-dependent increases in slopes. We present a new model to distinguish lateral growth mechanisms (lateral lengthening and/or rotation above a fixed tip). This model indicates that eastward lengthening of the Mushi anticline ceased by at least ~134 ka and its lateral growth has been dominated by rotation. Our study confirms that terrace deformation along a fold's strike not only can constrain the lateral lengthening rate but can serve to quantify the magnitude and rate of lateral rotation: attributes that are commonly difficult to define when relying on other geomorphic criteria.
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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... 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
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The lateral expansion and upward growth of the Tibetan Plateau remains enigmatic, despite its relevance for exploring both the geodynamics responsible for the world's largest topographic perturbation and its climatic consequences.... more
The lateral expansion and upward growth of the Tibetan Plateau remains enigmatic, despite its relevance for exploring both the geodynamics responsible for the world's largest topographic perturbation and its climatic consequences. Here we apply (U-Th)/He thermochronology, detrital zircon provenance, and magnetostratigraphy to constrain the timing and nature of uplift, erosion, and deposition along a transect that crosses the plateau's NE
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The dynamics of bedrock channel systems largely dictate the pattern and tempo of landscape evolution in tectonically active mountain belts. Recent theoretical models suggest that the topographic characteristics of bedrock channels (i.e.,... more
The dynamics of bedrock channel systems largely dictate the pattern and tempo of landscape evolution in tectonically active mountain belts. Recent theoretical models suggest that the topographic characteristics of bedrock channels (i.e., gradient and concavity) should reflect the interactions of rock-uplift rate, substrate resistance, and the erosive ability of the river. At present, however, these interactions are poorly calibrated. Here we investigate the topographic characteristics of bedrock channels developed across the southern flank of the Santa Ynez Mountains in California. This study area provides unique insights into the controls on channel profiles because: 1) numerous short, steep bedrock streams drain the southern flank of the range, 2) flights of marine terraces of known age define the rates and patterns of rock uplift, 3) rock-uplift rates exhibit pronounced variability along strike of the range (from 6 mm/yr), and 4) dramatic contrasts in substrate lithology exist orthogonal to the range but are nearly constant along strike. A comparison between streams experiencing higher rates in excess of 6 mm/yr was made through both digital elevation model analysis and field surveys. Regression analysis of river slope against drainage area taken from longitudinal stream profiles yields both the channel concavity as well as a channel steepness index (a relative measure of channel gradient similar to Hack's stream-gradient index) for each stream. We find that streams running through regions of constant lithology (or at least rocks exhibiting comparable rock strength) have "typical" concavities within the range of 0.4 - 0.6. These values are consistent with those predicted by a simple stream power model. However, where streams cross from areas of harder sandstones into regions of weaker sands and shales, concavity values are much higher, typically exceeding 1. These data imply that variablility in rock strength exhibits a strong influence on channel profiles in this field site. Additionally, we compared streams that are confined to regions of similar rock type, but that are experiencing different rock-uplift rates. Preliminary results show that a six-fold increase in rock-uplift rate induces a three-fold steepening in comparison to the low-uplift part of the mountain range, suggesting a non-linear dependence of channel gradient on uplift rate and/or the presence of thresholds in channel incision.
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The late Miocene Shadow Valley basin formed above the Kingston Range/Halloran Hills detachment system due to regional extension. The fault's original geometry is corrugated (curviplanar), and cuts earlier structures of the southern... more
The late Miocene Shadow Valley basin formed above the Kingston Range/Halloran Hills detachment system due to regional extension. The fault's original geometry is corrugated (curviplanar), and cuts earlier structures of the southern Cordillera thrust belt. Synformal corrugations cut the entire belt and locally into the craton. Small, proximally sourced basins, which are involved in the deformation at the breakaway fault, form in these synformal corrugations. The footwall thrusts are not affected by Tertiary transverse folding and their traces continue unwarped across areas where they are cut out by the detachment. This indicates that the curviplanar nature of the detachment surface is primary. Paleodrainage data in the form of paleocurrents, clast counts, and three-dimensional mapping of facies indicate long-lived westward transport derived from the footwall. In particular, clasts are sourced from the footwall east of the forward-most Mesozoic thrust. Source lithologies include c...
The Nepalese Himalaya, which is perhaps the quintessential collisional orogenic belt, presents a unique opportunity to examine changes in denudation rates over the last few million years. We document the low-temperature cooling history... more
The Nepalese Himalaya, which is perhaps the quintessential collisional orogenic belt, presents a unique opportunity to examine changes in denudation rates over the last few million years. We document the low-temperature cooling history along the Marsyandi river catchment in central Nepal with apatite fission track (AFT) and (U-Th)/He analyses, which are commonly used to estimate denudation rates and are especially powerful if combined on samples collected at different elevations along a vertical transect. The Marsyandi catchment has its headwaters at the edge of the Tibetan Plateau and traverses the High Himalaya to the east of Annapurna. In order to document the most recent denudation rates possible, we collected samples along the Marsyandi catchment (near river bed level), where ages should be the youngest, as well as on 3 nearly vertical transects on the western side of the Marsyandi catchment. The southernmost vertical transect (south of the High Himalaya) consisted of 7 samples...
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The Nepalese Himalaya, one of the world's major active collisional orogenic belts, presents a unique opportunity to examine changes in cooling and by extrapolation, denudation rates over the last 2 million years. Our study is focused... more
The Nepalese Himalaya, one of the world's major active collisional orogenic belts, presents a unique opportunity to examine changes in cooling and by extrapolation, denudation rates over the last 2 million years. Our study is focused on the Marsyandi drainage in central Nepal, from which we have collected a large suite of samples from along the river bed level as well as from multiple vertical transects spanning >3 km of elevation. We are using apatite fission track (AFT) and (U-Th)/He analyses to document the low-temperature cooling histories of these samples, and to get a detailed understanding of the cooling and denudation history of the Marsyandi drainage in order to evaluate the various controls (tectonic and climatic) on landscape evolution. The southernmost sample, collected 15 km south of the Main Central Thrust system, yielded the oldest AFT age of 3.8 Ma. In contrast, the river-level samples from north of the Main Central Thrust system yielded ages 2 km of elevation...
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Considerable effort over the last decade has focused on describing and quantifying transport laws and landscapes processes through the use of digital elevation models (DEM). Although an invaluable tool in many studies, DEM resolution must... more
Considerable effort over the last decade has focused on describing and quantifying transport laws and landscapes processes through the use of digital elevation models (DEM). Although an invaluable tool in many studies, DEM resolution must be applied appropriately in order to adequately characterize the landscape process or response of interest. In the case of channel initiation, several studies have documented a deviation from fluvial slope-area scaling relationships at drainage areas of approximately 0.1 km2, representing a threshold at which hillslope/mass wasting processes begin to dominate. In this study, we revisit the concept of channel initiation thresholds by analyzing slope-area relationships for a set of channels in southern California using DEMs of varying spatial resolutions: 30 m (SRTM), 2.5 m (stereo-pair SPOT), 1 m (stereo-pair airphotos, NAPP), and 10 cm (terrestrial LiDAR) resolution DEMs. We analyzed the following aspects: 1) the variability in slope-area scaling b...
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Orographic precipitation gradients across the Himalaya affect the altitudinal distribution of glaciers and indicate that these gradients underwent significant changes during the last local glacial maximum. Although many Himalayan glaciers... more
Orographic precipitation gradients across the Himalaya affect the altitudinal distribution of glaciers and indicate that these gradients underwent significant changes during the last local glacial maximum. Although many Himalayan glaciers are nurtured by avalanches from large headwalls, small glaciers permit reconstruction of both modern and past glacial snowlines. We focus on the Marsyandi River catchment in central Nepal, where we have established a meteorological network. In operation since 1999, these stations provide a direct measure of modern precipitation and temperature. The change in equilibrium line altitudes (ELA's) of this region's small glaciers is primarily influenced by summer precipitation. Weather stations above 3000 m record a pronounced, orographically controlled gradient in summer precipitation, ranging from >4300 mm on the southern, monsoon-side to <400 mm in the northern rainshadow, over a distance of 40 km. In response to the decreasing input of ...
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Recent studies indicate that variations in surface loads associated with the evolution of ice caps or lakes can modulate the stress pattern inside the crust [e.g. Hampel et al., 2007; Luttrell et al., 2007; Turpeinen et al., 2008]. In... more
Recent studies indicate that variations in surface loads associated with the evolution of ice caps or lakes can modulate the stress pattern inside the crust [e.g. Hampel et al., 2007; Luttrell et al., 2007; Turpeinen et al., 2008]. In particular these studies point out that such variations may be large enough to change the stress acting on faults and modify the timing of the seismic cycle and long-term slip rates. Glacial loads can impact the stress regime of mountain ranges in different ways, by simultaneously (1) loading with ice masses and (2) unloading it by bedrock erosion promoted by glacial processes. Furthermore, as a response to climate changes, major glacier retreats and advances occur with durations of a few kyrs, inducing fast rates of variation for the crustal stress field. An ongoing debate in Himalayan geodynamics concerns the deformation distribution inside the range and how the ~20 mm/yr of convergence that is accommodated by the orogen is partitioned between the di...
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ABSTRACT Intermontane basins are illuminating stratigraphic archives of uplift, denudation and environmental conditions within the heart of actively growing mountain ranges. Commonly, however, it is difficult to determine from the... more
ABSTRACT Intermontane basins are illuminating stratigraphic archives of uplift, denudation and environmental conditions within the heart of actively growing mountain ranges. Commonly, however, it is difficult to determine from the sedimentary record of an individual basin whether basin formation, aggradation and dissection were controlled primarily by climatic, tectonic or lithological changes and whether these drivers were local or regional in nature. By comparing the onset of deposition, sediment-accumulation rates, incision, deformation, changes in fluvial connectivity and sediment provenance in two interrelated intermontane basins, we can identify diverse controls on basin evolution. Here, we focus on the Casa Grande basin and the adjacent Humahuaca basin along the eastern margin of the Puna Plateau in northwest Argentina. Underpinning this analysis is the robust temporal framework provided by U-Pb geochronology of multiple volcanic ashes and our new magnetostratigraphical record in the Humahuaca basin. Between 3.8 and 0.8 Ma, ~120 m of fluvial and lacustrine sediments accumulated in the Casa Grande basin as the rate of uplift of the Sierra Alta, the bounding range to its east, outpaced fluvial incision by the Río Yacoraite, which presently flows eastward across the range into the Humahuaca basin. Detrital zircon provenance analysis indicates a progressive loss of fluvial connectivity from the Casa Grande basin to the downstream Humahuaca basin between 3 and 2.1 Ma, resulting in the isolation of the Casa Grande basin from 2.1 Ma to &lt;1.7 Ma. This episode of basin isolation is attributed to aridification due to the uplift of the ranges to the east. Enhanced aridity decreased sediment supply to the Casa Grande basin to the point that aggradation could no longer keep pace with the rate of the surface uplift at the outlet of the basin. Synchronous events in the Casa Grande and Humahuaca basins suggest that both the initial onset of deposition above unconformities at ~3.8 Ma and the re-establishment of fluvial connectivity at ~0.8 Ma were controlled by climatic and/or tectonic changes affecting both basins. Reintegration of the fluvial network allowed subsequent incision in the Humahuaca basin to propagate upstream into the Casa Grande basin.
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A new division of Middle and Late Pleistocene alluvial sequence in the north piedmont of the Chinese Tian Shan based on geomorphologic, stratigraphic, and chronologic criteria provides a framework for examining their relationship to... more
A new division of Middle and Late Pleistocene alluvial sequence in the north piedmont of the Chinese Tian Shan based on geomorphologic, stratigraphic, and chronologic criteria provides a framework for examining their relationship to climate change during glacial–interglacial transitions. Over the past 550kyr at least four major alluviation episodes occurred within the piedmont. Along the major river valleys in this region, each episode of alluvial fan deposition morphologically correlates with a major river terrace. These correlations create a regionally applicable framework for subdivision of the Quaternary alluvial sequence in the study area, where seven stepped river terraces are defined. Our new chronology of this fluvial sequence suggests that, following intervals of aggradation, three highest river terraces and equivalent alluvial fans were abandoned at ∼530ka, ∼300ka and ∼10ka, respectively. Paleosols at the base of the loess sequences that directly overlie the older terraces...
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Three successive zones of fault-related folds disrupt the proximal part of the northern Tian Shan foreland in NW China. A new magnetostratigraphy of the Taxi He section on the north limb of the Tugulu anticline in the middle deformed zone... more
Three successive zones of fault-related folds disrupt the proximal part of the northern Tian Shan foreland in NW China. A new magnetostratigraphy of the Taxi He section on the north limb of the Tugulu anticline in the middle deformed zone clarifies the chronology of both tectonic deformation and depositional evolution of this collisional mountain belt. Our ∼1200-m-thick section encompasses the upper Cenozoic terrigenous sequence within which ∼300 sampling horizons yield an age span of ∼8–2 Ma. Although the basal age in the Taxi He section of the Xiyu conglomerate (often cited as an indicator of initial deformation) is ∼2.1 Ma, much earlier growth of the Tugulu anticline is inferred from growth strata dated at ∼6.0 Ma. Folding of Neogene strata and angular unconformities in anticlines in the more proximal and distal deformed zones indicate deformation during Miocene and Early Pleistocene times, respectively. In the Taxi He area, sediment-accumulation rates significantly accelerate at...