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Few modern sediment dispersal pathways predate the breakup of Pangea. This suggests that river lifespan can be controlled by continental assembly and dispersal cycles, with the longest-lived river systems present during supercontinent regimes. Based on the strikingly similar age spectra and Hf isotopic array extracted from Paleozoic to early Mesozoic sedimentary sequences from the Paleo-Tethyan margin basins, we argue that a long-lived supercontinental- scale system, with headwaters originating in Antarctica, flowed northward to finally debouch on the margin with the Paleo-Tethys Ocean. Channel-belt thickness scaling relationships, which provide an estimate of drainage area, support the notion that this was a supercontinental-scale system. Sediments were eroded from Proterozoic orogenic belts and flanked resistant kernels of Archean cratons. Remnants of this system, which can still be traced today as topographic lows, controlled post-breakup drainage patterns in Gondwanan fragments in Western Australia. We conclude that supercontinental regimes allow sediment dispersal systems to be long-lived, as they provide both an abundant sediment supply, due to erosion of large-scale, collision-related internal mountain systems, and a stable, large-scale configuration that lasts until breakup. [ABSTRACT FROM AUTHOR]

A change in tectonics affects erosion rates across a mountain belt, leading to a period of non-steady sediment flux delivery downstream. The nonlinear relationship between tectonics and transient sediment delivery from an erosional catchment makes extraction of paleo-tectonic signals from stratigraphy challenging. We use a numerical landscape evolution model to explore how sediment flux from an erosional watershed responds to non-steady rock uplift. We focus on the time lag between the onset of a rock uplift change and the onset of a corresponding change in the sediment flux and the magnitude of the sediment flux relative to the steady rate. We observe that (1) sediment flux does not always record changes in the rock uplift rate when the duration of a rock uplift interval is less than 25% of landscape response time, or time for a landscape to transition from one steady state to another after a perturbation; (2) sediment flux response to variable rock uplift is positively correlated with the duration of rock uplift intervals; and (3) a nonlinear response between erosion rates and tectonic perturbations can result in increasing sediment flux through time even after rock uplift rate decreases. How quickly the sediment flux signal responds to a perturbation depends on how close the landscape was to steady state before the perturbation. These results illustrate conditions under which tectonic signals have the potential to be stored in the stratigraphic record or lost in an erosional system, and the importance of network dynamics for understanding signal propagation. [ABSTRACT FROM AUTHOR]

We provide model evidence for a previously unexplored positive feedback between tectonic strain and fluvial erosion by considering rock erodibility as a function of shear damage. Plastic shear strain permanently damages the upper crust within planar shear zones, providing a greater ease for detachment and transport by fluvial processes. The subsequent rapid erosion of exposed shear zones reforms the topographic stress field in a way that encourages continued accommodation of strain, a positive feedback response that becomes more prominent with greater shear damage. Based on model results and natural examples, rock strength heterogeneity plays a major role in the evolution of drainage network patterns and the capability for valley-scale strain localization in active orogens. [ABSTRACT FROM AUTHOR]

Identifying topographic and erosion rate response to tectonic and climatic forcing remains challenging. This is in part because of the difficulty in isolating the respective roles of climate and tectonics. Here we exploit 2500 thermochronometric data points collected over several decades of research, using a new inverse technique, to image the space-time evolution of erosion rate across the European Alps over the past 35 m.y. The most striking feature of our results is a two- to three-fold increase in erosion rate over the past 2 m.y. exclusively within the Western and Central Alps. This increase appears to be controlled by the inferred high rock uplift rate due to the progressive detachment of the European slab under the Western Alps. The similarity in mean elevation between the Western and Eastern Alps indicates a surprisingly low topographic response to this differential tectonic forcing, and points to the role of enhanced glacial erosion in response to surface uplift. [ABSTRACT FROM AUTHOR]

Analog and numerical models predict a coupling between climate and tectonics whereby erosion influences the deformation of orogens. A testable prediction from modeling studies is the decrease in width of mountain ranges as a result of increased precipitation. Here we evaluate the effect of climate on a critically tapered orogen, the central Andes, using sequentially restored, balanced cross sections through wet (15°-16°S) and dry (21°S) regions of the orogen. In these regions, tectonics, basin geometry, and style of deformation are similar, allowing us to use variations in propagation (or changes in percent shortening) to evaluate whether alongstrike changes in width and morphology are climate driven in the north. Results indicate similar total percent shortening along the northern (40%) and southern (37%) sections, suggesting that a wetter climate has not limited the width (propagation) in the north. However, comparison of early (45-25 Ma) and recent (ca. 20-0 Ma) shortening indicates that early deformation produced 45% ± 2% shortening of both sections, while recent deformation produced 41% ± 2% (north) versus 32% ± 2% (south) in the actively deforming Subandes. The latter suggests a coupling between climate and tectonics that began between ca. 19 and 8 Ma, and continues to 0 Ma, potentially limiting the width of the northern Subandes by ∼40 km. [ABSTRACT FROM AUTHOR]

Ongoing oblique collision and flat-slab subduction of the Yakutat terrane has produced Earth's highest coastal mountain range, the Chugach-St. Elias orogen in Southeast Alaska. Massive glaciers and ice fi elds cause extensive erosion, but also limit access to rocks that allow detailed study of the orogen. Fission track and U/Pb dating of detrital zircon from glacial rivers reveal the exhumation history of the Chugach-St. Elias orogen. Orogenic development started ca. 30 Ma and pulses of exhumation occurred 20 ± 2 Ma and 11 ± 2 Ma. Differential exhumation occurred across major fault zones and the locus of exhumation shifted southward. The ca. 5 Ma cooling ages of detrital zircon in the Pliocene-Pleistocene Yakataga Formation reveal that source rock exhumation was likely associated with faulting along the ice-covered Fairweather fault-Contact fault system. [ABSTRACT FROM AUTHOR]

In Gobi Altay and Altay, Mongolia, several flat surfaces, worn through basement rocks and uplifted during the ongoing tectonic episode to a similar altitude of 4000 m, suggests disruption of a single large-scale surface. New thermochronology and field data show that the plateau surfaces represent uplifted parts of an ancient peneplain that formed during Jurassic time. The Gobi Altay and Altay flat-topped massifs are tectonically and geomorphologically unique. Their preservation for ∼150 m.y. implies that no further tectonic movements occurred before the onset of the last deformation episode, 5 ± 3 m.y. ago. It also suggests that very low erosion rates were maintained by a dry climate over millions of years. [ABSTRACT FROM AUTHOR]

The plateau edge of southern Oman is used as a natural laboratory to independently test apatite fission-track analysis, (U-Th)/He dating, and stratigraphy as methods for quantifying post-rift erosion depths and lithospheric response at passive margins. A mappable unconformity between the Proterozoic basement and the low-conductivity, pre-rift sediment cover links residual buttes preserved at the coast to the escarpment, and therefore imposes tight limitations on parameter choices for modeling the Cenozoic topographic evolution. A mean geothermal gradient of ∼33 °C km-1 ensures the best fi t between the thermochronologic data and the stratigraphically defined coast-to-scarp maximum denudation depth of ∼1.75 km. With a lithospheric elastic thickness of 7 km, the resulting flexural response generates a retreat and uplift of the escarpment associated with a seaward downwarp of the unconformity, made possible because denudation minima are inboard of the escarpment and sediment loading occurs offshore. This closed experiment confirms the value of low-temperature thermochronology as a tool for quantifying long-term erosion, but also highlights the benefits of including independent stratigraphic information in terms of obtaining more plausible solutions. This study suggests that post-rift downwarping of eroded rift shoulders can occur, and may have not been commonly detected because low-temperature thermochronology data sets lack both suitable geologic data and intrinsic sensitivity. [ABSTRACT FROM AUTHOR]

Laser-ablation 40Ar/39Ar step-heating analyses of 20 pseudotachylyte veins from a single location along the exhumed central portion of the active Alpine fault of New Zealand yield total gas age values between 1 and 19 Ma. Evidence shows that they are genetically related and were formed during coeval episodes of seismogenic melting at shallow crustal depth, contrasting with a spread in formation ages. The total gas ages show an exponential decrease with increasing proportion of melt matrix and K content, reflecting incomplete degassing and mixtures of radiogenic Ar sources. Calculation of intercepts for all-melted matrix and all-clast end-member components indicate ca. 570 ka (Quaternary) friction-melting ages of ca. 332 Ma (Lower Carboniferous) source rock. Assuming an average exhumation rate of 6–9 mm/yr for uplift and erosion, these results imply that friction melts were generated during major slip episodes at ∼3.5–5 km crustal depth. We conclude that reliable dating of young pseudotachylyte can be accomplished by combining chronologic study with clast-matrix quantification of genetically related vein assemblages. [ABSTRACT FROM AUTHOR]

The high elevation and deep incision of the Alps have traditionally been used as an argument for recent tectonic activity that has elevated the belt and increased erosion rates. Normal faulting and horizontal extension, however, dominate current tectonic activity, and isostatic compensation of thinning crust should lead not to increased but to decreased mean elevations. Here we test the idea that enhanced Quaternary erosion of the Alps and isostatic compensation of the mass removed can account for the distribution of present-day geodetically measured rates of vertical movement in the western Alps. Using geophysical relief and Kuhlemann's estimated average erosion rate for the Alps, we quantify the spatial distribution of erosion and the volume of eroded rock, respectively. From these, we obtain a map of rock eroded within a given time span. The calculated isostatic response of the Alpine lithosphere to erosional unloading for a variety of values of the flexural rigidity of the Alpine lithosphere reaches a maximum of ~500 m since 1 Ma in the inner Swiss Alps, and vertical movement extends across the entire belt, including peri-Alpine basins. Assuming a steady erosion rate since 1 Ma, this rebound accounts for half of the measured vertical motion of 1.1 mm/yr in the southern Valais. Thus, a significant fraction (~50%) of the present-day vertical movement results from the isostatic response to enhanced erosion during Plio-Quaternary time. [ABSTRACT FROM AUTHOR]

The geometry of foreland basins is controlled by a dynamic balance between thrust-belt migration, flexural subsidence, and fluvial deposition. To improve our ability to quantify the relationships between tectonics, climate, and foreland basin geometry, I developed analytic solutions for basin topography and stratigraphy using a classic two-dimensional mathematical model of foreland basin evolution. Model predictions for basin topography are successfully tested against observed profiles along a humid-to-arid climatic gradient in the central Andes. Using published estimates for the thrust-belt migration rate, flexural parameter, and thrust-front basin depth in this region, I show that basin topographic profiles can be used to estimate the upstream erosion rate at any point along a foreland basin. Basin-averaged erosion rates estimated in this way vary from 0.025 to 0.045 mm/yr in the central Andes, increasing from semiarid to humid climates. [ABSTRACT FROM AUTHOR]

A fundamental objective in studies of climate-erosion-tectonics coupling is to document convincing correlation between observable indicators of these processes on the scale of a mountain range. The eastern Himalayas are a unique range to quantify the contribution of tectonics and climate to long-term erosion rates, because uniform and steady tectonics have persisted for several million years, while monsoonal precipitation patterns have varied in space and time. Specifically, the rise of the Shillong plateau, the only orographic barrier in the Himalayan foreland, has reduced the mean annual precipitation downwind in the eastern Bhutan Himalaya at the Miocene-Pliocene transition. Apatite fission-track (AFT) analyses of 45 bedrock samples from an E-W transect along Bhutan indicate faster long-term erosion rates outside of the rain shadow in the west (1.0–1.8 mm/yr) than inside of it in the east (0.55–0.85 mm/yr). Furthermore, an AFT vertical profile in the latter segment reveals a deceleration in erosion rates sometime after 5.9 Ma. In this drier segment of Bhutan, there are remnants of a relict landscape formed under a wetter climate that has not yet equilibrated to the present climatic conditions. Uplift and preservation of the paleolandscape are a result of a climate-induced decrease in erosion rates, rather than of an increase in rock uplift rate. This study documents not only a compelling spatial correlation between long-term erosion and precipitation rates, but also a climatically driven erosion-rate change on the scale of the eastern Himalayas, a change that, in turn, likely influences that region's recent tectonic evolution. [ABSTRACT FROM AUTHOR]

This study examines the response of a forearc to the increase in sediment flux to the trench caused by the onset of glacial denudation in the Patagonian Andes. We investigated shelf-coastal basins in south-central Chile, which generally comprise Eocene-early Miocene nearshore facies overlain by late Miocene-early Pliocene deep-water siltstones and by late Pliocene-Quaternary nearshore deposits. Seismic profiles and coastal exposures reveal Eocene-early Pliocene extension followed by ongoing late Pliocene compression evidenced from growth strata adjacent to seismically active reverse faults. The onset of major global cooling ca. 6 Ma triggered glacial denudation in the uplifted high Andes. Exhumed material transported along the steep and humid Andean western slope increased trench sedimentation rates and caused continuous accretion and subduction of terrigenous material. We interpret forearc basin inversion as a response to a decrease in slope and basal friction of the wedge caused by frontal accretion and subduction of water-rich material, respectively, in order to reach a critical taper. This process lifted the shelf ∼1.5 km during the middle Pliocene. The Juan Fernández Ridge and Chile Rise confined >2 km trench fill between 45 and 34°S, limiting accretion and basin inversion. Glacial age trench fill and the steady decrease in plate convergence rate shifted this segment of the margin from erosive to accretionary during the Pliocene. [ABSTRACT FROM AUTHOR]

Seamount subduction along subduction-zone plate boundary thrusts has long been implicated as a mechanism for abrasion and tectonic erosion of the base of the overriding plate. However, tectonic erosion processes have not been examined in detail with high-quality three-dimensional (3-D) seismic reflection imaging. In 1999 we acquired 3-D seismic reflection data from the Nankai Trough subduction zone to image the plate boundary fault and the overlying accretionary wedge structure. Fortuitously, these data reveal a small (to 1 km high) basement ridge that has subducted to 7 km subseafloor. Updip from the basement ridge, a 1-km-thick sequence of sediment from the base of the accretionary wedge appears to be missing. We interpret these data as evidence for tectonic erosion of the base of the accretionary wedge following the basement ridge subduction. Tectonic erosion has removed more than 25 km³ from the updip edge of the seismogenic zone and carried it down into the seismogenic zone. The tectonically eroded sediments are presumed to enhance fault-zone fluid content, potentially reducing fault-zone effective stress, and may temporarily inhibit earthquake rupture potential. After the passage of the ridge the boundary fault returns to its former position in a period of enhanced underplating. [ABSTRACT FROM AUTHOR]

At the end of the Miocene, the European Alps ceased outward expansion, and tectonic uplift and exhumation shifted into the orogen interior. This shift is consistent with a change from orogenic construction to orogenic destruction, reflecting an increase in the ratio of erosional flux to accretionary flux. The coincidence of this change with an increase in sediment yield from the Alps suggests a climate-driven increase in erosional flux. The timing of deformation and sediment release from the southern Alps indicates that the tectonic change occurred synchronous with the last phase of the Messinian salinity crisis. We attribute the increase in erosional flux to a climatic shift to wetter conditions throughout Europe, likely augmented by the base-level fall that occurred during the Mediterranean dessication. This climate change is represented in the stratigraphic record by the Lago Mare deposits of the Mediterranean salinity crisis. [ABSTRACT FROM AUTHOR]

We present a thermal model of a simple thrust system that can be used to determine thrust rates and erosion rates from low-temperature thermochronology. Unlike previous models, this model incorporates the effects of erosion both during and after thrusting. In particular, we examine the modeled evolving thermal structure and pressure-temperature- time evolution of hanging-wall rocks that undergo fault-bend folding due to transport over a blind footwall ramp. In all cases, rocks cool as they move over the footwall ramp, potentially providing a common pinpoint for determining thrust rates. In the simplest case, low-temperature thermochronology of minerals that pass through their closure temperature over the ramp will yield details on thrust kinematics (thrust rate, timing of initiation, and duration of thrusting). Additional cooling ages of a more comprehensive sample suite can capture cooling due to erosion. In these latter cases, model results can place limitations on erosion rates. [ABSTRACT FROM AUTHOR]

Thermal-mechanical numerical experiments are used to consider if the influence of surface erosion during continental plate collision and orogenesis extends beneath the crust into the mantle lithosphere. The models demonstrate that the modification of crustal mass flux by surface denudation can change the evolution of the deforming crust and consequently alter the behavior of the crust-mantle interface. The mantle lithosphere responds to these variable dynamics: with active surface erosion, stable subduction-like plate consumption is maintained; in the absence of erosion, subduction is inhibited by accumulating crust, causing the convergent plates to steepen dip, detach, and reverse consumption polarity. With strong subducting plates, the removal of surface processes can trigger a transition from stable subduction to delamination and/or retreat of the convergent plate. The influence of surface erosion is less important for mantle lithosphere undergoing Rayleigh-Taylor-type dripping and is not significant at ocean plate collision, where there is relatively little buoyant crust to clog the subduction zone. The results of the experiments demonstrate that in certain tectonic regimes the influence of climate-controlled surface processes may reach much deeper into the lithosphere than has previously been appreciated. [ABSTRACT FROM AUTHOR]

We report a magnetostratigraphic and rock magnetic study of the Yaha section, located on the southern flank of the central Tian Shan mountains, Asia. Our results show a two-fold increase in sedimentation rate as well as marked changes in rock magnetic characteristics ca. 11 Ma. After 11 Ma, sedimentation rate remained remarkably constant until at least 5.2 Ma. These findings are consistent with sedimentary records from other sections surrounding the Tian Shan. We conclude that uplift and erosion of the Tian Shan accelerated ca. 11 Ma, long after the onset of the collision between India and Asia, and that the range rapidly evolved toward a steady-state geometry via a balance between tectonic and erosion processes. [ABSTRACT FROM AUTHOR]

Thermal histories derived from apatite fission-track data are remarkably consistent irrespective of tectonic setting and overall rate of cooling. Rapid cooling through the partial annealing zone is typically followed by slower cooling, and such histories can only be explained by systematic errors in the experimentally derived annealing rates used to determine the thermal histories, or a consistent geotherm shape characterized by a relatively low geothermal gradient in the uppermost crust. Differences between the cooling paths characterizing individual tectonic settings indicate that geotherm shape influences the cooling histories. This suggests that crustal geotherms, especially those in orogenic belts, are characterized by a shallow zone of high permeability, allowing the rapid transfer of heat by fluid advection, perhaps together with a near-surface zone affected by enhanced heat loss due to topographic effects. The influence of such controls on cooling histories must be considered prior to using thermochronology data to constrain denudation histories. [ABSTRACT FROM AUTHOR]

Refolding structures in the Aliaga area (Iberian Chain, Spain) show how erosion can exert a control on the geometry of buckle fold interference. Early Miocene ENE-trending buckle folds are superposed on a large NNW-SSE anticline (Eocene-Oligocene). North of Aliaga, the earlier hinge zone in the competent limestone unit controlling buckling (Urgon facies, Lower Cretaceous) constitutes a mechanical obstacle to refolding, which induces development of essentially conical type 2 interference. To the south, erosional removal of the hinge zone at that competent unit allowed the near-vertical eastern limb to behave as independent layers, being refolded into cylindrical, near-vertical-axis folds showing a snake-like map pattern. Lower Miocene conglomerates containing pebbles of Jurassic origin, whose source area was the core of the earlier NNW-SSE-trending anticline, indicate that this Jurassic core had been effectively exhumed before refolding occurred. In this way, snake-like folds constitute a new case of erosion-controlled tectonic structure. [ABSTRACT FROM AUTHOR]

The Martian hemispheric dichotomy shows compressional features a few hundred kilometers south of the dichotomy boundary, and contemporaneous extensional features along the boundary. Two processes that may have contributed to the observed deformation are lateral lower-crustal flow and erosion. Crustal flow causes a decrease in crustal thickness in the south, and an increase in the north. The result is compressional surface stresses in the highlands and extensional stresses around the dichotomy boundary. The magnitude, location, and timing of the predicted stresses are consistent with the observed tectonic features and strongly suggest that moderate lateral flow occurred. For the nominal heat flux and rheology, sufficient lateral flow is generated for a mean crustal thickness of 70 km. Erosion generates extension in the south and compression in the north, opposite to what is observed. Either erosion only resulted in local, as opposed to regional, distribution of highland material, or the rigidity of the lithosphere was sufficiently high at the time of erosion that significant stresses did not develop. [ABSTRACT FROM AUTHOR]

We use multichannel seismic reflection (MCS) and gravity data from the southern IzuBonin convergent plate margin to test for tectonic erosion. The Hahajima Seamount is a serpentinite seamount on the Izu-Bonin forearc. This serpentinite body likely originated from the mantle wedge beneath the Izu-Bonin arc, but it subsequently detached. MCS data and gravity modeling demonstrate that the Ogasawara Plateau on the incoming Pacific plate has been partly subducted beneath the Hahajima Seamount. Our analysis indicates that the Hahajima Seamount is a "rootless" serpentinite seamount, and the "root" of the serpentinite body was eroded during subduction of the western edge of the Ogasawara Plateau. Structural features of the Hahajima Seamount, the Ogasawara Plateau, and the Philippine Sea plate suggest that tectonic erosion, particularly basal erosion, has been occurring throughout this area. [ABSTRACT FROM AUTHOR]

Cratonic uplift or subsidence, as recorded geologically by erosion or deposition, indicates the net change in lithospheric buoyancy. Density change is primarily controlled by temperature change, such that the geologic record reveals the net lithospheric heating or cooling. Our modeling shows that thermal stabilization of lithosphere can occur in <100 m.y., largely determined by the time for crustal radioactivity to warm the entire lithosphere. Longer-term thermal evolution (350-400 m.y.) is controlled by the feedback between isostatic and thermal responses. Crustal heat production is the dominant factor for evolution of crustal geotherms, whereas the detailed initial thermal structure is less important. The fact that many cratons are eroded to only modest depths indicates that they have a history of warming slightly since their formation, implying a rather cool 700-1000 °C for initial lithospheric mantle. This is consistent with the growth of cratonic lithosphere by progressive thickening during continental assembly and/or subduction stacking of oceanic lithosphere. Relatively warm early lithosphere due to elevated crustal heat production or higher initial lithospheric mantle temperatures may have had a lower preservation potential due to preferential deformation and destruction. Study of the Proterozoic orogen of the southwestern United States indicates that the distinct thermal and isostatic records of adjacent crustal blocks are compatible with observed differences in crustal heat production, but also with similar initial lithospheric mantle temperatures. [ABSTRACT FROM AUTHOR]

Following a change in the rate of convergence in a collision zone, the rate of rock uplift also changes. This results in a change in relief, and hence in erosion rate. Thus, over time, the erosion rate tends to adjust to equal the rock-uplift rate. A perturbation analysis of a mountain mass at critical taper suggests that the time constant for this adjustment varies from 10[sup 5] to >10[sup 8] yr, depending on initial relief, lithology, and erosion law. Under most conditions, time constants for the adjustment are long enough to preclude attainment of a steady state during a typical orogeny lasting on the order of 10[sup 7] yr. However, if erosion increases exponentially with relief, a close approach to a steady state is possible in the relatively few mountain belts on Earth with exceptional relief and/or weak lithologies. [ABSTRACT FROM AUTHOR]

Examines the impact of continental erosions on the climate and tectonic influences in South America. Ratios of terrigenous oxide minerals; Distribution of increased sediment accumulation; Role of tectonics and climate change in long-term erosions of the Amazon Basin.

Discusses the mechanisms of dynamic system of tectonics and erosion. Nature of steady state; Characterization of orogenic system; Dependence of erosion rate on relief and elevation.

The article focuses on the issues of tectonic and climatic influences on vertical displacement in the Western European Alps. It highlights the significances of applying the modern spatial correlation methods in determining the tectonic and climate variables. It discusses the positive outcomes of the entire study. In addition, modern methods and observations of strain, erosion, and climate can essentially contribute further understanding of the coupled climate and tectonic systems.