IRTG-StRATEGy - Tectonics

163-G 2.2

henry.wichura — Thu, 16 Jun 2016 15:57:50 +0000

Multiple basin filling and excavation cycles and fault reactivation

Working Package:

Temporal Process:

Prof. Manfred Strecker, Ph.D.Potsdam University Prof. Dr. Ricardo AlonsoSalta University (ARG)Prof. Dr. Fernando HongnSalta University (ARG)

163-G 1.5/G 1.6

henry.wichura — Thu, 31 Mar 2016 09:10:46 +0000

01|2016 – 03|2021

Investigating geologic archives of changes in erosion rates and hillslope processes in response to climate forcing

The principal aim of these two Postdoc projects is to determine how climate shifts and variability influence the dynamics of surface processes and affect landscape evolution over various timescales. Given the demonstrated sensitivity of landscape denudation rates to precipitation along the steep slopes of the eastern margin of the Andean Plateau¹, we hypothesize that the generation of thick late Pleistocene sedimentary fill terraces is linked to wetter climate conditions, and possibly also to changes in the variability of rainfall. Modern station observations of weather and sediment transport provide a detailed perspective on how climate variability can affect surface processes, but modern records often span insufficient time periods to characterize aspects of the system that change slowly, yet fundamentally influence the rate at which sediment can be created and mobilized from the Earth’s surface. These aspects include shifts and successional changes in vegetation, the rates at which soil forms and evolves, local sediment storage capacity, and tectonic forcing. By combining data from (1) weather and stream stations, (2) sedimentary archives (lake sediment cores, fluvial fill terraces), and (3) paleoclimate and paleovegetation proxies, we will achieve a multi-temporal perspective on how landscapes respond to climate shifts and changes in climate variability. Parallel efforts to map active structures and their influence on modern river profiles will allow us to identify regions in which recent changes in tectonic forcing is unlikely. These observations will embody a holistic set of empirical observations with which numerical landscape evolution models can be tested and refined. Special attention will be paid to the roles of climate-dependent biological (vegetation) and chemical processes, which are often neglected in considerations of climate-driven landscape dynamics. The first Postdoc project [G 1.5] will focus on comparing modern and paleo-erosion rates derived from cosmogenic nuclides with modern and paleo-climate signals derived from stable isotopes in biomarkers, in each case sampling both modern sediment and sediment from dated fill terraces. The second Postdoc project [G 1.6] will focus on integrating the field data into numerical landscape evolution models, to better understand the effects of different timescales of forcing (e.g., ENSO versus glacial-interglacial forcing) and any changes in surface processes that may explain variations in sediment mobilization and transport (e.g., landslides/debris flows versus soil creep). This work will complement ongoing efforts to understand modern sedimentary dynamics in the intermontane basins of the Argentine Andes, where aggradation of modern rivers has been tentatively been linked to a shift in the amount and variability of rainfall recorded at stream gauge and weather stations in the same areas where the extensive late Pleistocene fill terraces occur. Furthermore, comparisons between the fill terraces and what appears to be a modern analog in the form of an active, 20 km² alluvial fan provides opportunities to relate processes occurring in the contributing area of the fan (e.g., frequent landslides and debris flows) to those that likely occurred during the late Pleistocene aggradational periods.

Working Package:

WP1 - Climate

Temporal Process:

Intermediate

Dr. Fabiana CastinoUniversity of Potsdam Dr. Heiko PingelUniversity of Potsdam Mitchell D'Arcy, Ph.D.GFZ Potsdam Dr. Stefanie TofeldePotsdam University Prof. Manfred Strecker, Ph.D.Potsdam University Prof. Dr. Ricardo AlonsoSalta University (ARG)Prof. Taylor Schildgen, PhD.GFZ Potsdam Prof. Dr. Fernando HongnSalta University (ARG)Dr. Elizabeth OrrUniversity of Potsdam

Bibliography:

¹Strecker and Bookhagen, 2012

163-G 3.3

Anonymous — Fri, 25 Sep 2015 10:14:50 +0000

10|2018 – 09|2021

Lithospheric-scale 3D configuration of the Central Andes and adjacent forelands: constraints on along- and across-strike variations of density, temperature and strength

Lic. Constanza Rodriguez PicedaGFZ Potsdam Dr. Judith Bott (née Sippel)GFZ Potsdam Prof. Dr. Magdalena Scheck-WenderothGFZ Potsdam Prof. Dr. Claudia PrezziBuenos Aires University

There is a great variability in observed crustal deformation style and intensity from the subduction trench across the highest Andes to the foreland lows as well as from the Northern to the Southern Central Andes. Beside the subducting plate that exerts important controls on deformation through its (spatially and temporally) varying dynamics, it is the intrinsic physical properties of the overriding plate that govern the formation of zones of crustal strength and weakness. With this project we want to explore the present-day compositional, thermal and rheological configuration of the Central Andes and adjacent forelands on a lithospheric scale by means of data-driven 3D numerical models. While in the first project phase of StRATEGy this work package focused on the Northern Central Andes, this follow-up project will investigate lithological and related physical heterogeneities of the sediments, the crystalline crust, and the mantle of the Southern Central Andes. For this purpose, geological and geophysical observations such as seismic, seismological, gravity and thermal data will be integrated into consistent 3D models. These static models will be useful to constrain numerical thermo-mechanical experiments (such as planned in project G 3.2) that explore the stress-and-strain relationships across the entire subduction system.

10|2015 – 09|2018

3D lithosphere-scale density and thermal structure of the Central Andean foreland basins

Since the late Oligocene, the intracontinental Chaco-Paraná basin system evolved contemporaneously with the adjacent Andean fold-and-thrust belt. Consequently, four characteristic foreland depozones with different sediment thickness have developed, including (from west to east) wedge-top, foredeep, forebulge, and backbulge depositional environments. In places, very young sedimentary sequences directly overlie basement rocks in the E, while toward the orogen, they cover several kilometres of Paleozoic and Mesozoic sediments. Geophysical data provides local information on the depth to the Moho and the lithosphere-asthenosphere-boundary (LAB); accordingly, the crust and lithosphere thin from ~43 km and ~120 km in the north-eastern parts of the Chaco-Paraná basin to ~35 km and ~80 km, respectively, in the central parts. Towards the Andean orogen in the west, crustal thicknesses increase to more than 60 km and the LAB deepens to more than 150 km. Despite the abundance of geological and geophysical data, there is currently no regionally consistent 3-dimensional representation of the entire lithosphere in the region. Such a model depicting the main compositional heterogeneities of the sediments, the crystalline basement, and the lithospheric mantle has recently been developed for the Central Andes and will be critical for unraveling the long-term evolution of the foreland basin. Based on geological maps, well-logs, and seismic data made available to StRATEGy from industry and our Argentine partner E. Rossello, regional thickness variations of main tectonostratigraphic units will be integrated in a 3D structural model in the framework of PhD project. Subsidence rates and spatiotemporal shifts of depocentres will be cast in terms of phases of increased Andean tectonic loading. The models developed in this project will provide boundary conditions for petroleum-potential assessment in project [G 3.1] and a regional tectonic framework for project [G 3.4]. Furthermore, these models will allow rheological heterogeneities to be distinguished, particularly crustal zones of mechanical weakness, representing important constraints for large-scale numerical thermo-mechanical models developed in projects [G 3.2].

Working Package:

WP3 - Basin Modeling

Temporal Process:

Long Term

Intermediate

Dr. Christian MeeßenGFZ Potsdam Dr. Judith Bott (née Sippel)GFZ Potsdam Prof. Dr. Magdalena Scheck-WenderothGFZ Potsdam Prof. Dr. Claudia PrezziBuenos Aires University

163-G 3.1

Anonymous — Fri, 25 Sep 2015 10:13:20 +0000

10|2018 – 09|2021

Quantification of Central Andes growth and erosion in relation to sedimentation in the Neuquén and Colorado basins - a source-to-sink approach

Lic. Román FealGFZ Potsdam Dr. Robert OndrakGFZ Potsdam Prof. Dr. Matias GhiglioneBuenos Aires University (ARG)Prof. Dr. Laura GiambiagiCuyo National University (ARG)Prof. Manfred Strecker, Ph.D.Potsdam University

This project follows a source to sink approach relating Central Andes growth with sedimentation in Neuquén and Colorado basins. The working hypothesis is that tectonic mountain growth produces large volumes of eroded rocks and subsidence in the foreland basins that catches those sediments. While contractional tectonics accelerates subsidence rates of foreland basins, periods of neutral tectonics produce low to no accommodation space in the retroarc. On those cases, large portion of sediments will bypass the continent toward the offshore basins, therefore controlling overburden and petroleum generation. The idea is to compare the Central Andes (34°-42°SL) changing tectonics and exhumation rates - source region - with sedimentation rates and volumes of sediments in the Neuquén foreland basin to determine if there is an inverse correlation to the Colorado offshore basin - sink basins - for periods to be defined during data acquisition. In particular, we will test the hypothesis by calculating sedimentation rates in the Colorado offshore basin from available basin models. Sedimentation rates in the Neuquén basin and tectonic and exhumation in the Central Andes can be summarized from a plethora of publicly available data. We will study paradigmatic localities in the Neuquén basin to recognize the appearance of highly condensed stratigraphic sections representing periods of neutral tectonics. Lab analysis will be conducted in order to better constrain and characterize those periods of potential sediment bypass towards the offshore which is of significance for the evolution of the petroleum potential of the region. The project will also contribute to the partner projects [G 3.2] and [G 3.3] by providing data from the sedimentary cover of the region.

10|2015 – 09|2018

Tectono-stratigraphic evolution of the intermontane Salta basin and Chaco-Paraná foreland basin: characterization and evolution of petroleum potential

The evolution of the inter-mountain Salta basin is related to the evolution of the Central Andes. An intracontinental rift was formed by extensional processes and subsequently filled by up to 5500 m sediments from the Neocomian to the Paleogene intercalated by minor volumes of magmatic rocks. This complex constitutes the Salta group. Paleoenvironmental analysis reveals depositional history controlled by tectonic and climatic changes. Deformation of the basin began at the end of the Eocene and resulted in a rapid transition from a rift basin to a foreland basin filled by synorogenic continental deposits. The Chaco-Paraná Basin comprises the undeformed Chaco-Parana plain to the east, and the Subandes, Sierras Pampeanas, and the ranges of the Santa Barbara System to the west. The basin comprises >10 km of sediments spanning the Silurian to the Present. It is asymmetric, with a total stratigraphic thickness of Cenozoic rocks >7.5 km deposited at the western margin that thin eastward. Deformation of the Subandes and the Salta Basin developed since the Eo-Oligocene; and is characterized mainly by in-sequence, thin-skinned thrusting that includes ramp anticlines and passive roof duplexes separated by thrust faults and synclines, although Plio-Pleistocene out-offsequence thrusting has also been reported. The Subandes are home to several major gas discoveries during the last 20 years. The Chaco-Paraná foreland basin, as a frontier exploration area, has a high resource potential (some assessments attribute almost one third of Argentina’s total unconventional hydrocarbon potential to this basin), although exploration concepts are largely unproven. By combining 3D petroleum system modeling techniques with detailed source rock and petroleum-accumulation information, volumetric assessments of petroleum potential can be produced at different scales for basin wide assessments of the possible resource potential. We plan to investigate the evolution of the inter-mountain Salta basin and the Chaco-Parana Basin to deconvoluting its burial and thermal histories as well as source rock maturation, petroleum generation, migration, accumulation and leakage. A detailed basin modeling study is planned which integrates the tectono-stratigraphic evolution, timing of major unconformities, spatiotemporal migration of depocenters, source-rock occurrence and type to elucidate the hydrocarbon generation and migration history of this basin. Special focus will be put on the climatic and tectonic processes operating in the sediment source areas to determine the main variables and forcing conditions controlling the stratigraphic architecture and the distribution of source rocks. Within this context including all information available on the crustal evolution of the NW of Argentina is a pre-requisite. Especially the buildup of the Andes, and fault reactivation and thrusting along the basin margins are important factors in controlling both the burial as well as the maturation and petroleum migration histories. This project will provide an integrated and concise description of the evolution of Salta and Chaco-Parana basin petroleum systems. The project will cooperate closely with projects [G 3.3] and [G 3.4] to define boundary conditions for basin modeling and detailed description of the tectono-stratigraphic and sedimentary evolution of the basin.

Working Package:

WP3 - Basin Modeling

Temporal Process:

Long Term

Intermediate

Dr. Ricardo Ruiz MonroyGFZ Potsdam Dr. Robert OndrakGFZ Potsdam Prof. Dr. Magdalena Scheck-WenderothGFZ Potsdam Prof. Dr. Eduardo RosselloBuenos Aires University (ARG)Prof. Dr. Brian HorsfieldGFZ Potsdam

163-G 2.3

Anonymous — Fri, 25 Sep 2015 10:12:05 +0000

10|2018 – 09|2021

Depositional and exhumation history of the Cretaceous Lomas de Olmedo rift basin

M.Sc. Willemijn van KootenPotsdam University apl. Prof. Edward Sobel, Ph.D.Potsdam University Dr. Cecilia Del PapaCórdoba University (ARG)Dr. Alejandro BandeTectpetrol S.A. Buenos Aires (ARG)Dr. Daniel StarckTecpetrol A.S. Buenos Aires (ARG)Prof. Dr. Patricio PayrolaSalta University (ARG)

The Salta Rift in NW Argentina is an intracontinental rift with thick syn- and post-rift deposits that have been extensively explored for petroleum. The Lomas de Olmedo and the Tres Cruces sub-basins are E-W and N-S trending portions of the rift, respectively. The majority of the former sub-basin lies in the subsurface, to the east. The transition zone between these rift segments outcrops ~20 km east of Humahuaca, where the thick Cianzo syncline provides stunning exposures of the entire syn- and post-rift section. The Hornocal fault bounds the syncline and formed the northern margin of the rift. Published structural mapping and unpublished apatite fission track data show that the Cretaceous Hornocal normal fault has been inverted in the Miocene. There are prominent angular unconformities in the syncline that separate syn- and post-rift strata; these appear to delineate growth strata associated with the fault. Therefore, this locality provides an excellent opportunity to study proximal rift-margin sedimentary deposits as well as to study the exhumation history of the adjacent rift shoulder. We plan to conduct zircon (U-Th)/He thermochronology to constrain the Cretaceous exhumation of the rift shoulder. We will also examine post-rift, Cenozoic reactivation of structures using apatite fission track thermochronology. In the basin, the syn-rift sequence reportedly contains carbonate nodule-bearing paleosols. We will analyze these using both stable isotopes for paleoclimate analysis and U/Pb dating for age control. Stratigraphic, sedimentologic, provenance, and structural studies will characterize the basin fill. We plan to examine along-strike variations of rift shoulder exhumation with the aid of subsurface data from the Lomas del Olmedo sub-basin to the east.

10|2015 – 09|2018

The influence of inherited extensional structures on the growth of basement-cored ranges and their foreland basins

The reactivation of pre-existing normal faults during subsequent contractile deformation can exert a profound influence on both exhumation of ranges and sedimentary basin formation. This topic has been addressed in the well-exposed, arid intermontane basins and ranges of NW Argentina as well as more humid sectors of the broken foreland farther east. However, the more humid eastern flank of the Sierras Pampeanas has been less well-studied, despite its simpler structural history. In the Tucumán and Choromoro basins, structures that deform the foreland basins as well as their sedimentary thicknesses have been well analyzed using industry seismic reflection data. However, to date, a quantitative source-to-sink approach has not been applied in this area. Therefore, we will integrate thermochronology, structural data, and provenance and basin analysis to test whether Cretaceous normal faults exert a first-order control on the pattern and magnitude of Cenozoic contractile deformation in basement-cored ranges as well as subsidence patterns in the adjacent foreland basins. The ages of the largely continental foreland-basin fill remain imprecisely constrained, with the exception of the strata corresponding to the Middle Miocene Paraná marine transgression, reflecting both the difficulty of dating non-marine sequences and the poor outcrop quality. To address this problem, we will constrain depositional ages by dating interbedded volcanic ashes using either zircon U/Pb or 40Ar/39Ar dating. Furthermore, we will collect sandstone samples for detrital zircon geochronology using LA-ICP-MS to provide maximum depositional ages. Together, this approach will enable us to derive realistic models of flexural basin subsidence, especially in the vicinity of spatially disparate basement uplifts. Reconstructions of range exhumation and sediment deposition will be accomplished by using apatite fission-track dating on detrital sandstones to determine changes in lag time. Where possible, we will conduct double dating (fission track and U/Pb) to better constrain a local versus distal source for these sediments. We will also extend the database of basement thermochronologic data in Sierra Aconquija and the Cumbres Calchaquies to evaluate the timing and magnitude of exhumation of both Cretaceous and Cenozoic structures. These two ranges are along strike from each other and bound the Tucumán and Choromoro basins, respectively used thermochronology to delineate the extent of Cretaceous rift structures within these ranges. As the Sierra Aconquija was strongly exhumed in the Neogene while the Cumbres Calchaquíes were primarily exhumed during the Cretaceous, this region provides an ideal setting to examine the influence of pre-existing normal faults on Cenozoic evolution.

Working Package:

WP2 - Tectonics

Temporal Process:

Long Term

Dr. Sebastian Zapata HenaoPotsdam University apl. Prof. Edward Sobel, Ph.D.Potsdam University Dr. Cecilia Del PapaCórdoba University (ARG)

163-G 2.1

Anonymous — Fri, 25 Sep 2015 10:11:09 +0000

10|2018 – 09|2021

Quaternary landscape evolution Paleoseismology and active tectonics of the NW-Argentineian broken foreland under the influence of tectonic processes.

M.Sc. Gregor Lauer-DünkelbergPotsdam University Prof. Manfred Strecker, Ph.D.Potsdam University Prof. Dr. Fernando HongnSalta University (ARG)Dr. Carolina Montero LopezIBIGEO Conicet

Fault systems in the broken foreland of NW Argentina are associated with isolated seismicity, deformation, and uplift, and they pose a major problem in understanding the spatiotemporal characteristics of individual earthquakes and long-term deformation patterns. Range uplift in these environments is highly disparate in time and space, without a clear deformation front as in the foreland fold-and-thrust belt to the north. Some ranges constitute large anticlines that have formed over blind thrusts, such as the growing anticlines west of the town of Salta.

On geological time scales, the erratic tectonic behavior of fault-bounded intermontane basins has caused a disturbance of the fluvial systems and resulted in multiple episodes of basin filling and sediment removal to the foreland. Importantly, there appears to be a relationship between sediment removal and ensuing changes in crustal stresses in these environments. For example, fault reactivation within and along basin margins is observed to follow the removal of the sedimentary load on time scales of several 105 years.

To elucidate the mechanisms by which such fault arrays in broken forelands organize, activate, and deactivate over time, we will compare geomorphic and geologic records that integrate the activity of faults over multithousand-year timescales (i.e., by dating deformed geomorphic features such as fans and terraces using U/Pb dating) to million-year timescales (i.e., by applying geochronologic and thermochronologic methods). These types of observations will enable the determination of the spatiotemporal faulting history and help to assess how deformation may be transferred between fault fault systems over long timescales (PhD1). We will furthermore use the Gale geodynamic model 87 to study how topographic construction and changing constitutive properties of fault zones may moderate the transfer of deformation between such arrays (PhD2).

As deformation accrues and mountain ranges are built, body forces in the crust may cause one set of structures to become less susceptible to failure relative to surrounding structures. Deformation may then systematically migrate from areas of higher to lower elevations. However, coeval erosional processes export mass from the basins and ranges, and so may buffer the accumulation of body forces in the crust. Gale allows application of surface-processes rules, enabling us to couple erosion at the surface to changes in the deformation field within the upper crust. Combining field observations, geochronology and modeling is expected to help us ascertain plausible causal mechanisms of spatiotemporal patterns of deformation.

10|2015 – 09|2018

Spatiotemporal characteristics of paleo-, historic and recent earthquakes in the broken foreland of the south-central Andes

In this project we will investigate large and medium-magnitude earthquakes using waveform analysis of historical and modern seismograms for event location, magnitude, and depth as well as focal mechanisms and source-time function. Historical earthquakes recorded at analog stations worldwide (primarily recorded on paper or film) since the beginning of the last century can be digitized and analyzed with advanced methods to better constrain their characteristics. For example, using waveform inversion, we are able to derive depth, lateral extent, and the true fault plane as well as zones of increased slip along rupture planes. With such a data set, we aim to identify and quantify the related earthquake surface-rupture trace or remnants of earlier surface ruptures in the epicentral regions. High-resolution satellite imagery, aerial photography, cosmogenic nuclide exposure dating of offset geomorphic markers, fault scarp measurements, and fault trenching will complement this analysis and provide an unprecedented data set to assess earthquake characteristics. We will focus on the large magnitude, shallow crustal seismic events in the region in the Andean foreland, e.g., the 1894 (M8), 1908 (M6.8), 1929 (M6.5), 1944 (M7.8), 1952 (M7.0) and 1977 (M7.4) events. Depending on the quality of historic records and local conditions, we will select two sites (preferably the 1894 and 1952/1977 San Juan events). For these sites, we will relocate medium-size earthquakes, determine their seismic moment tensors (focal mechanisms) and depth from waveform inversion and thereby test possible relationships between recent seismic activity and surficial deformation characteristics. Deployment of temporary seismic stations in addition to existing permanent stations at one or two selected sites will help identify active structures from small magnitude events. We will reevaluate seismic-moment tensors for the foreland region for recent events, where the magnitude threshold depends on data availability. Taken together, the results will provide better insight into the relationships between aseismic and seismic deformation, the identification of active structures, and possible changes in the spatiotemporal deformation characteristics of important structures. Such knowledge will ultimately shed light on the dynamics of Quaternary tectonic activity compared to the overall tectonic and topographic evolution of ranges in the broken foreland and help elucidate the background sedimentation rates and patterns in light of tectonic forcing mechanisms.

Working Package:

WP2 - Tectonics

Temporal Process:

Short Term

Dr. Martin ZeckraPotsdam University apl. Prof. Dr. Frank KrügerPotsdam University Prof. Dr. Fernando HongnSalta University (ARG)Dr. Patricia AlvaradoSan Juan University (ARG)

163-G 1.2

Anonymous — Fri, 25 Sep 2015 10:08:52 +0000

10|2018 – 09|2021

The role of mass wasting in glacial forelands of the Andes

M.Sc. Elisabeth SchönfeldtPotsdam University Prof. Oliver Korup, PhD.Potsdam University Dr. Diego WinocurBuenos Aires University (ARG)

Large segments of the Andean foreland have been repeatedly shaped by Quaternary glaciations. The many diagnostic landforms include large glacial lakes, staircases of moraine ridges, and extensive outwash plains, and have inspired generations of Quaternary geologists to reconstruct the processes, magnitude, and timing of ice build-up and decay along the mountain front, adding to a reference chronology of Southern hemisphere glaciations. What only a few of these studies have noticed are several hundreds of very large (>>10⁶m³) mass-wasting deposits that fringe the Andean foreland. Many of these debris mounds intersect with many well-dated moraine ridges or former meltwater-lake shorelines and offer exciting opportunities of exploring the hitherto largely unknown role of mass wasting in the glacial forelands of the Andes.

Studying the timing of these large landslides provides a stringent test for models of paraglacial landscape evolution. Preliminary work on large landslides glacial moraines indicates that moraines can fail catastrophically several thousand years after they formed. Several landslide bodies entered former glacial lakes shown by distinct horizontal breaks in landslide deposit morphology, thus raising the possibility of past and future landslide tsunamis.

The project aims to understand what we can learn from and what can we generalize about the mass-wasting activity of low-gradient glacial forelands. The Andean foreland may well host the largest cluster of (relatively) dated large, low-gradient landslides on Earth, which so far has been elusive in studies of the Andean sediment cascade. How does this estimate compare to sediment transport data, and what do we learn about sediment transfer from glaciated mountain belts to their proximal forelands?

10|2015 – 09|2018

Rock slides vs. rock glaciers: feeding the central Andean sediment cascade

This project explores the role of both large (>10⁶ m³) catastrophic rock slides and rock glaciers as prime movers of the central Andean sediment cascade. Recent hypotheses concerning the triggers of large non-volcanic bedrock landslides in the central Andes favor earthquakes, judging from the distribution of tell-tale landslide deposits with respect to active faults and shallow seismicity. Rock glaciers share a very similar topographic niche, but are traditionally viewed as diagnostic of sporadic alpine permafrost, though they may have also originated from earthquake-triggered supraglacial rock slides. Rock slides and rock glaciers are not only voluminous point sources of coarse debris, but also decisive barriers to incoming sediment flux. The aim of this project is to quantify to first order the regional net balance between such sediment release and sequestration by large rock slides and rock glaciers in central Andean headwaters using a multi-scale methodology: First, we will expand an existing regional inventory of large landslides and rock glaciers in the region to quantify the spatial pattern, topographic characteristics, and volumetric distribution of large Andean debris deposits from digital topography and remote sensing data. We will compare classic operator-based mapping with state-of-the-art automated object-oriented mapping techniques. Second, fieldwork will involve local ground truthing of landslide and rock-glacier geometries and provide vital input data for gauging regional volumetric budgets of denudation rates and intermittent sediment storage. We will estimate the fraction of valley fills causally linked to catastrophic slope failure and rock-glacier dynamics to gauge the overall relevance of catastrophic hillslope input to the central Andean sediment cascade. Samples collected in the field will further provide age constraints of strategically selected rockslide and rock-glacier surfaces or correlate backwater sediments with ¹⁴C, ¹⁰Be, lichenometry or dendrochronology, depending on available samples. Third, we will quantify metrics of geomorphic impact of these deposits on the fluvial network (changes in fluvial transport capacity, formation of knickpoints, epigenetic bedrock meanders, etc.), and the sediment cascade (barrier lakes, floodplain aggradation, etc.). We will expand existing numerical models of channel adjustment to landslide and rock glacier impacts to estimate fluvial response and recovery times. Similar work that we conducted in other regions revealed decisive controls of large landslide deposits on bedrock channel geometry, and the size and age distribution of valley fills that are potential sinks of alluvial georesources. Moreover, large river-blocking rock slides and rock glaciers may form important temporary buffers to incoming, and potentially adverse, sediment pulses from local disturbances.

Working Package:

WP1 - Climate

Temporal Process:

Short Term

M.Sc. M.Sc. Julia DrewesPotsdam University Prof. Oliver Korup, PhD.Potsdam University Prof. Dr. Stella MoreirasCuyo National University (ARG)