Current Topography Research Articles

Comment on “Modeling and prediction of natural gas fracking pad landscapes in the Marcellus Shale region, USA” by Qingming Meng

In modeling and prediction of natural gas fracking pad landscapes in the Marcellus Shale region, USA, the author asserts that landscape and environmental characteristics are the driving factors behind the siting of natural gas pads in the southwestern area of the Marcellus Shale, Pennsylvania, USA. In the article, the author largely dismisses the importance of geology for site prediction. Although the study is useful for understanding landscape characteristics in a small area of the Marcellus Shale, his premise that “the key variables for natural gas fracking can be landscape and environmental variables rather than geological variables” is flawed and thus could lead to erroneous assumptions when creating land use plans. A more reasonable assumption is that the surface siting of natural gas wells is secondary to geologic considerations, as the current topography bears little influence on the geology.

Biogeographic distribution patterns and their correlates in the diverse frog fauna of the Atlantic Forest hotspot.

Anurans are a highly diverse group in the Atlantic Forest hotspot (AF), yet distribution patterns and species richness gradients are not randomly distributed throughout the biome. Thus, we explore how anuran species are distributed in this complex and biodiverse hotspot, and hypothesize that this group can be distinguished by different cohesive regions. We used range maps of 497 species to obtain a presence/absence data grid, resolved to 50×50 km grain size, which was submitted to k-means clustering with v-fold cross-validation to determine the biogeographic regions. We also explored the extent to which current environmental variables, topography, and floristic structure of the AF are expected to identify the cluster patterns recognized by the k-means clustering. The biogeographic patterns found for amphibians are broadly congruent with ecoregions identified in the AF, but their edges, and sometimes the whole extent of some clusters, present much less resolved pattern compared to previous classification. We also identified that climate, topography, and vegetation structure of the AF explained a high percentage of variance of the cluster patterns identified, but the magnitude of the regression coefficients shifted regarding their importance in explaining the variance for each cluster. Specifically, we propose that the anuran fauna of the AF can be split into four biogeographic regions: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests; b) northern small-ranged species that presumably evolved within the Pleistocene forest refugia; c) highly diverse and small-ranged species from the southeastern Brazilian mountain chain and its adjacent semideciduous forest; and d) southern species from the Araucaria forest. Finally, the high congruence among the cluster patterns and previous eco-regions identified for the AF suggests that preserving the underlying habitat structure helps to preserve the historical and ecological signals that underlie the geographic distribution of AF anurans.

Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography

Abstract Simultaneous full-depth microstructure measurements of turbulence and finestructure measurements of velocity and density are analyzed to investigate the relationship between turbulence and the internal wave field in the Antarctic Circumpolar Current. These data reveal a systematic near-bottom overprediction of the turbulent kinetic energy dissipation rate by finescale parameterization methods in select locations. Sites of near-bottom overprediction are typically characterized by large near-bottom flow speeds and elevated topographic roughness. Further, lower-than-average shear-to-strain ratios indicative of a less near-inertial wave field, rotary spectra suggesting a predominance of upward internal wave energy propagation, and enhanced narrowband variance at vertical wavelengths on the order of 100 m are found at these locations. Finally, finescale overprediction is typically associated with elevated Froude numbers based on the near-bottom shear of the background flow, and a background flow with a systematic backing tendency. Agreement of microstructure- and finestructure-based estimates within the expected uncertainty of the parameterization away from these special sites, the reproducibility of the overprediction signal across various parameterization implementations, and an absence of indications of atypical instrument noise at sites of parameterization overprediction, all suggest that physics not encapsulated by the parameterization play a role in the fate of bottom-generated waves at these locations. Several plausible underpinning mechanisms based on the limited available evidence are discussed that offer guidance for future studies.

Coupling Basin and Reservoir Simulators for an Improved CO2 Injection Flow Model

Abstract The goal of this work is to model the present basin-scale groundwater flow of the Paris basin with a basin modelling approach and to use it to initialise a reservoir model for CO 2 injection. It is part of the ULTimateCO2 FP7 European funded project which aims to significantly enhance our knowledge of specific processes that may affect the long-term fate of geologically stored CO 2 . Basin models simulate the history of sedimentary basins through time by coupling geological events such as deposition, erosion, compaction, structural deformation and subsurface flow simulation. In order to construct the basin model of the Paris Basin in IFPEN basin software TemisFlow®, several types of data were gathered. The current surface topography and 11 horizons representing the top of selected main geological layers (from basement to surface) were constructed from outcrop boundaries, wells and isobath maps. Seven erosion maps for the main unconformities recorded in the Paris Basin were also constructed to complete the burial history of the sedimentary basin. TemisFlow® computes pressure, temperature and salinity fields over the basin history up to the present-day. The final state of the basin simulation is then used as initial state of the reservoir numerical model (Coores TM ). The latter is used to simulate the injection of CO 2 and its effects on the pressure field for instance.

Impact of bedrock surface topography on spatial distribution of Quaternary sediments and on the flow pattern of late Weichselian glaciers on the East European Craton (Russian Plain)

This paper presents the first high quality maps of the bedrock surface topography and the Quaternary sediment distribution for the Late Weichselian glaciation area on the East European Craton (EEC) and the reasoning behind the estimated sediment distribution. Geographic information system (GIS)-based three-dimensional model of the bedrock surface topography, the current digital terrain model (DTM), and the ice flow pattern of the last glaciation provided the main source data for the analyses and interpretations. In the current continental area of the western EEC, which was covered by the last Scandinavian Ice Sheet (SIS), the bedrock lies overwhelmingly (85%) above the contemporary sea level, with an average altitude of ~54m above sea level. The topography of the bedrock surface is very well reflected in the current topography, and an 80-m difference in the ice bed surface altitudes results in the topographic focusing of the ice flow, and thus all late Weichselian ice streams were accommodated to the depressions in the subglacial surface. Such depressions are characterised by a thin (<10-m) layer of sediment with one till bed. Just 50m upslope from the bottom of the depressions, the thickness of the sediment increases two- to threefold and comprises five or more till layers, indicating relief enhancement through subsequent glaciations. The average calculated thickness of the Quaternary deposits in the study area was ~49m, and the total volume of sediments was ~20,280km3.

Editorial (Thematic Issue: Advances in Research on Pharmacological Targets for Pain Relief)

Several years ago, a former hot topic volume of Current Neuropharmacology assembled elegant reviews and perspectives that summarized and discussed state-of-the-art advances in research on the neurobiology of pain [1]. The current topography of the field is highlighting the need for new updates of scientific achievements and their pharmacological prospects. Viewpoints and technologies evaluating pain states have gradually evolved and novel pain target molecules are emerging. Newly discovered molecules shed light on future developments of promising pharmacological approaches. Accordingly, this issue collected highly insightful and informative reviews reflecting the many aspects of progress in the pain research. In the first review, Dr. Enrique J. Cobos and Dr. Enrique Portillo-Salido asked essential questions regarding the translational processes in the assessment of pharmacological potencies and efficacies. They sought to revise both our focus and view on the examination of therapeutic prospects during the preclinical period by intensively discussing the validity of pain assessment systems. Dr. Fumimasa Amaya, Dr. Yuta Izumi, Dr. Mika Sasaki, and Dr. Megumi Matsuda introduced a variety of pro-nociceptive mediators generated under injury conditions and discussed the associated mechanisms that drive pain hypersensitivity at the peripheral level and the validity of the molecular components as pharmacological targets. In the following review, Dr. Nicolas Cenac emphasized the crucial roles of protease-activated receptors and their signal transductions in visceral pain from the gut, pancreas and bladder as well as in functional bowel disorders. Dr. Seungkyu Lee described pain transmission and plasticity via the action of various neuronal voltage-gated calcium channels. Furthermore, for their inhibitors ranging from traditional to atypical ones, detailed molecular mechanisms and beneficial outcomes for chronic pain were summarized. The role of potassium channels is as important as that of excitatory ion channels in nociceptive firing. Dr. Nikita Gamper and Dr. Xiaona Du highlighted potassium channels as validated pain targets by extensive examination of evidence from molecular biology, physiology, and pharmacology. Very recently, the calcium-activated anion channel Anoctamin 1 made its debut as an important transducer for thermal pain and inflammatory mediator-induced pain. Dr. Hawon Cho and Dr. Uhtaek Oh, the researchers who first discovered this ion channel molecule, offered an in-depth analysis of its role in peripheral pain sensation. The importance of sensory TRP channels in the pain killing strategies has been established over the course of a decade. Dr. Hongzhen Hu, Dr. Jialie Luo, Dr. Edgar T. Walters, and Dr. Susan M. Carlton provided a review concerned with major issues regarding the TRP-mediated pain and their synthetic ligands. Resolvins and related omega-3-derived lipid substances are emerging as pro-resolving and anti-inflammatory mediators. Lastly, Dr. Sun Wook Hwang, Dr. Sungjae Yoo, and Dr. Ji Yeon Lim discussed their pain-killing aspects and druggability by reviewing recent results from analgesic assessments. The series of excellent reviews presented in this special issue will lead to a comprehensive understanding of the current trends in pain physiology and pharmacology research. Furthermore, hopefully this volume will help readers to generate future creative pain hypotheses, and to propose practical insights aimed at developing novel painkilling strategies.

Sediment budget quantification of a sub-Alpine river catchment since the end of the last glaciation

Changes in sediment budget and quantification of sediment fluxes of a small (5.3km2) Mediterranean sub-Alpine river catchment (Charanc catchment, Southern French Alps, 44°30′44N/5°51′55E) are estimated for the last 20,000years using a GIS-based approach and 3D palaeotopographic reconstructions. Following field surveys, a high-resolution morphometric map was established. Ten 14C ages of sub-fossil trees and charcoal beds were compiled. All datasets were integrated into a Geographic Information System. We computed three palaeosurfaces by masking the Digital Elevation Model of the current topography, and calculated the sediment budget of the catchment. Estimations of specific hillslope erosion, sedimentation and export rates highlight the evolution of the catchment and its sensitivity to variations in the ratio of sediment load to stream discharge. Between 20,000 and 14,500cal.BP, sediment that was eroded (37millionm3) within the Charanc catchment was entirely exported. A change to a sedimentation regime commenced at around 14,500cal.BP. Between 9000cal.BP and 7000cal.BP, footslopes were buried by fan-shaped deposits at a rate of 6700m3/yr. Since 7000cal.BP, the overall morphogenetic regime has been one of vertical incision. 73% of the material eroded over the last 14,500years (14millionm3) was stored in fan-shaped deposits. At the present time, 46% of this volume (6millionm3) is still stored in the catchment. 8millionm3 of sediments have thus been exported out of the Charanc catchment since 14,500cal.BP. Annual specific erosion rates on marly slopes are estimated at: (1) 98 to 111t/ha/yr for the period 20,000–14,500cal.BP, which is comparable to present rates measured on denudated marls in the Southern French Alps, under a probably climate-driven erosion regime, and (2) 17 to 20t/ha/yr since 14,500cal.BP, a reduction in erosion rate that may have been favoured by a more extensively wooded landscape.

Updating known distribution models for forecasting climate change impact on endangered species.

To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their distributional response to climate change, especially under the current situation of rapid change. However, these predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of known species distribution models, but proceeding to update them with the variables yielded by climatic models before projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered Bonelli's Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that the main threat for this endangered species would not be climate change, since all forecasting models show that its distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of linking conservation biology with distribution modelling by updating existing models, frequently available for endangered species, considering all the known factors conditioning the species' distribution, instead of building new models that are based on climate change variables only.

Modelling North American palaeo-subglacial lakes and their meltwater drainage pathways

This paper presents predictions of palaeo-subglacial lakes and their drainage pathways beneath the North American Ice Sheet during the last glaciation. We utilise data on the current topography and seafloor bathymetry, and elevation models of the ice- and ground-surface topography from data-calibrated glaciological modelling to calculate the hydraulic potential surface at the ice-sheets bed. Given that specific ice-surface elevations are only known from modelled outputs, and thus contain significant uncertainty, we utilise many such outputs to examine where on the bed that subglacial lakes are likely to have occurred. Our analysis demonstrates the potential for subglacial lake genesis, particularly beneath the former Cordilleran Ice Sheet; along the suture zone between the Laurentide and Cordilleran ice sheets; in Hudson Bay; in the Great Lake basins and deep trenches of the Canadian Archipelago. During the Last Glacial Maximum we suggest that at least 1000km3 of meltwater could have been stored subglacially. As the ice-sheet and the bed evolved subglacial lakes repeatedly formed and emptied, particularly in Hudson Bay and the suture zone between the Laurentide and Cordilleran ice sheets where lakes were characteristically broad and shallow (<10m deep). In contrast, the Cordilleran Ice Sheet was characterised by deep (up to ∼90m) and persistent lake genesis. Significantly, similar distributions and modes of predicted subglacial lakes are obtained irrespective of the model or model run, which suggests the results are robust. Subglacial meltwater drainage varied between stable networks, typically associated with strong topographic controls, and convoluted networks that underwent considerable dynamism, including repeated meltwater network capture. These lake likelihood predictions could usefully form targets for detailed field and remote investigations and we hypothesise and explore the potential that numerous deposits and spillways previously interpreted as arising from ice-marginal lakes may have emanated from their subglacial cousins.

LaAlO3/Si capacitors: Comparison of different molecular beam deposition conditions and their impact on electrical properties

A study of the structural and electrical properties of amorphous LaAlO3 (LAO)/Si thin films fabricated by molecular beam deposition (MBD) is presented. Two substrate preparation procedures have been explored namely a high temperature substrate preparation technique—leading to a step and terraces surface morphology—and a chemical HF-based surface cleaning. The LAO deposition conditions were improved by introducing atomic plasma-prepared oxygen instead of classical molecular O2 in the chamber. An Au/Ni stack was used as the top electrode for its electrical characteristics. The physico-chemical properties (surface topography, thickness homogeneity, LAO/Si interface quality) and electrical performance (capacitance and current versus voltage and TunA current topography) of the samples were systematically evaluated. Deposition conditions (substrate temperature of 550 °C, oxygen partial pressure settled at 10−6 Torr, and 550 W of power applied to the O2 plasma) and post-depositions treatments were investigated to optimize the dielectric constant (κ) and leakage currents density (JGate at |VGate| = |VFB − 1|). In the best reproducible conditions, we obtained a LAO/Si layer with a dielectric constant of 16, an equivalent oxide thickness of 8.7 Å, and JGate ≈ 10−2A/cm2. This confirms the importance of LaAlO3 as an alternative high-κ for ITRS sub-22 nm technology node.

Post-Miocene faults in Auckland: insights from borehole and topographic analysis

Although experiencing some seismicity, the Auckland region is generally considered to be one of New Zealand's most tectonically stable areas. There is a distinct lack of mapped faults in the central Auckland area, yet regional trends indicated by several mapped faults surrounding it suggest that these faults should continue through Auckland. The overprint of Auckland Volcanic Field (AVF) deposits may mask any potential fault traces in the area. We carried out a detailed study of the topography of Auckland concealed beneath the AVF deposits, using borehole and geophysical data, and combined this with structural information gleaned from current topography and exposed geology to identify significant concealed fault offsets. The reliability of each potential fault displacement was determined using pre-defined attributes. The resulting block faulting model for Auckland supports the proposed connection between the position of the Junction Magnetic Anomaly and Auckland volcanism. The identification of several possible faults in the area covered by the AVF might indicate more structural control on volcanism than previously thought.

Study on Gourband Fault Activity on the basis of Neotectonic Evidences (Northeast of Torbat-e-Jam)

Gourband is the largest fault in the Alluvial Sediments of Torbt-e-Jam Plain. This fault is extended from northwest to southeast. Regarding its adjacency to the town and various villages, it is important to study Geotectonic activity. It is found that there are various geomorphologic abnormities along Gourband Fault. In this research, the effect of current movements of this fault on the structural Geomorphology of this zone has been studied. Fault scarps redirecting rivers and channels, folds of quaternary deposits and discoloration of sediments in the fault fields are important geomorphologic indicators that found in the desert site and in association with movement on Gourband Fault. The dip of fault is 50-60 degrees. The reverse component causes uplifting that forms maintains and it controls the current topography of the areas. Also, direct of waterways indicates direct of moving strike- slip of fault. Regarding dextral displacement of these waterways, it is found dextral strike-slip movement in the fault. Elevation of Neogene's Sediments of the fault surface indicates uplifting and reverse component in the fault.

Study on Gourband Fault Activity on the basis of Neotectonic Evidences (Northeast of Torbat-e-Jam)

Gourband is the largest fault in the Alluvial Sediments of Torbt-e-Jam Plain. This fault is extended from northwest to southeast. Regarding its adjacency to the town and various villages, it is important to study Geotectonic activity. It is found that there are various geomorphologic abnormities along Gourband Fault. In this research, the effect of current movements of this fault on the structural Geomorphology of this zone has been studied. Fault scarps redirecting rivers and channels, folds of quaternary deposits and discoloration of sediments in the fault fields are important geomorphologic indicators that found in the desert site and in association with movement on Gourband Fault. The dip of fault is 50-60 degrees. The reverse component causes uplifting that forms maintains and it controls the current topography of the areas. Also, direct of waterways indicates direct of moving strike- slip of fault. Regarding dextral displacement of these waterways, it is found dextral strike-slip movement in the fault. Elevation of Neogene’s Sediments of the fault surface indicates uplifting and reverse component in the fault. Keywords: Fault Scarps Torbat-e-Jam, Geomorphology, Iran

Response timescales for martian ice masses and implications for ice flow on Mars

On Earth and on Mars, ice masses experience changes in precipitation, temperature, and radiation. In a new climate state, flowing ice masses will adjust in length and in thickness, and this response toward a new steady state has a characteristic timescale. However, a flowing ice mass has a predictable shape, which is a function of ice temperature, ice rheology, and surface mass-exchange rate. In addition, the time for surface-shape adjustment is shorter than the characteristic time for significant deformation or displacement of internal layers within a flowing ice mass; as a result, surface topography is more diagnostic of flow than are internal-layer shapes. Because the shape of Gemina Lingula, North Polar Layered Deposits indicates that it flowed at some time in the past, we use its current topography to infer characteristics of those past ice conditions, or past climate conditions, in which ice-flow rates were more significant than today. A plausible range of near-basal ice temperatures and ice-flow enhancement factors can generate the characteristic geometry of an ice mass that has been shaped by flow over reasonable volume-response timescales. All plausible ice-flow scenarios require conditions that are different from present-day Mars, if the basal layers are pure ice.

Stress free configuration of the human eye

Numerical simulations of eye globes often rely on topographies that have been measured in vivo using devices such as the Pentacam or OCT. The topographies, which represent the form of the already stressed eye under the existing intraocular pressure, introduce approximations in the analysis. The accuracy of the simulations could be improved if either the stress state of the eye under the effect of intraocular pressure is determined, or the stress-free form of the eye estimated prior to conducting the analysis. This study reviews earlier attempts to address this problem and assesses the performance of an iterative technique proposed by Pandolfi and Holzapfel [1], which is both simple to implement and promises high accuracy in estimating the eye's stress-free form. A parametric study has been conducted and demonstrated reliance of the error level on the level of flexibility of the eye model, especially in the cornea region. However, in all cases considered 3–4 analysis iterations were sufficient to produce a stress-free form with average errors in node location <10−6mm and a maximal error <10−4mm. This error level, which is similar to what has been achieved with other methods and orders of magnitude lower than the accuracy of current clinical topography systems, justifies the use of the technique as a pre-processing step in ocular numerical simulations.

Geomorphology and Late Holocene morphogenesis of Tchinguiz Tepe hill (Old Termez, Uzbekistan, Central Asia)

Tchinguiz Tepe Hill is the southernmost outcrop, interrupted at the shores of the Amu Darya, of the Cenozoic sediments that form the Baysuntau–Kugitangtau alignment. The initiation points of the recent morphogenesis are the slopes and a pediment controlled structurally by the unequally weathered substrate. The hill is covered by sediments of varying thickness on the south side, which is exposed to dominant winds from the SE and was occupied by humans, at least during Kushan times (1st and 2nd centuries AD). Its form is derived from two systems of natural processes (slope and aeolian) and an anthropic one, which have operated under arid-to-semiarid conditions. These processes have mobilized sands from the weathered substrate and from the Afghan dunes, and pebbles and gravels from early Kushan-time constructions, such as the fortress of the Tchingiz Tepe Hill. Slope-wash processes have contributed materials, which have evolved as slope-aeolian sediment in the mantled pediment. Part of the aeolian sand has been re-exported, together with primary (autochthonous) sand outside the hill towards the north. Thus, in Tchinguiz Tepe the current morphogenesis has slowed down considerably and is currently in dynamic equilibrium, with a slow increase in sediments. The carbonate crusts, which are not very well developed, have formed a complex host sediment. Anthropic morphogenetic action has modified the natural shape of the hill from the earliest times of occupation to the present day, and has generated materials that are now incorporated in the slope wash and govern the current topography and the distribution of sediments from the wall of the fortress and other buildings.

Measuring large topographic change with InSAR: Lava thicknesses, extrusion rate and subsidence rate at Santiaguito volcano, Guatemala

Lava flows can produce changes in topography of the order of 10s–100s of metres. A knowledge of the resulting volume change provides evidence about the dynamics of an eruption. Using differential InSAR phase delays, it is possible to estimate height differences between the current topography and a digital elevation model (DEM). This does not require a pre-event SAR image, so it does not rely on interferometric phase remaining coherent during eruption and emplacement. Synthetic tests predict that we can estimate lava thicknesses of as little as ∼9m, given a minimum of five interferograms with suitably large orbital baseline separations. In the case of continuous motion, such as lava flow subsidence, we invert interferometric phase simultaneously for topographic change and displacement. We apply this to Santiaguito volcano, Guatemala, and measure increases in lava thickness of up to 140m between 2000 and 2009, largely associated with activity between 2000 and 2005. We find a mean extrusion rate of 0.43±0.06m3/s, which lies within the error bounds of the longer term extrusion rate between 1922 and 2000. The thickest and youngest parts of the flow deposit were shown to be subsiding at an average rate of ∼−6cm/yr. This is the first time that flow thickness and subsidence have been measured simultaneously. We expect this approach to be suitable for measurement of landslides and other mass flow deposits as well as lava flows.

Assessment of flood hazard, vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km2) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.

MRI-based Preplanning Using CT And MRI Data Fusion In Patients With Cervical Cancer Treated With 3D-based Brachytherapy: Feasibility And Accuracy Study

MRI-based Preplanning Using CT And MRI Data Fusion In Patients With Cervical Cancer Treated With 3D-based Brachytherapy: Feasibility And Accuracy Study

Vertical tectonics at a continental crust‐oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia

The topographically prominent Sierra Nevada de Santa Marta forms part of a faulted block of continental crust located along the northern boundary of the South American Plate, hosts the highest elevation in the world (∼5.75 km) whose local base is at sea level, and juxtaposes oceanic plateau rocks of the Caribbean Plate. Quantification of the amount and timing of exhumation constrains interpretations of the history of the plate boundary, and the driving forces of rock uplift along the active margin. The Sierra Nevada Province of the southernmost Sierra Nevada de Santa Marta exhumed at elevated rates (≥0.2 Km/My) during 65–58 Ma in response to the collision of the Caribbean Plateau with northwestern South America. A second pulse of exhumation (≥0.32 Km/My) during 50–40 Ma was driven by underthrusting of the Caribbean Plate beneath northern South America. Subsequent exhumation at 40–25 Ma (≥0.15 Km/My) is recorded proximal to the Santa Marta‐Bucaramanga Fault. More northerly regions of the Sierra Nevada Province exhumed rapidly during 26–29 Ma (∼0.7 Km/My). Further northward, the Santa Marta Province exhumed at elevated rates during 30–25 Ma and 25–16 Ma. The highest exhumation rates within the Sierra Nevada de Santa Marta progressed toward the northwest via the propagation of NW verging thrusts. Exhumation is not recorded after ∼16 Ma, which is unexpected given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was very recent (i.e., ≤1 Ma?), and there has been insufficient time to expose the fossil apatite partial annealing zone.