Glacial Processes Research Articles

A long-term, high-latitude record of Eocene hydrological change in the Greenland region

A range of proxy approaches have been used to reconstruct short-term changes to Earth's hydrological cycle during the early Eocene hyperthermals. However, little is known about the response of Earth's hydrological and biogeochemical systems to long-term Cenozoic cooling, which began following the Early Eocene Climatic Optimum (53.3 – 49.4 million years ago; Ma). Here, we use the molecular distribution and isotopic composition of terrestrial biomarkers preserved in marine sediments of ODP Site 913, East Greenland, to develop a long-term record of high-latitude hydrological change between 50 and 34 Ma. There is a marked decline in the concentration of conifer-derived diterpenoids and angiosperm-derived triterpenoids during the Eocene. As the input of wind-blown conifer pollen remains stable during this interval, this implies that decreasing di- and triterpenoid concentrations reflect declining influence of fluvial inputs – and perhaps terrestrial runoff – throughout the Eocene. Branched GDGTs and bacterial-derived hopanes indicate an increased input of soil- and kerogen-derived organic matter, respectively, after 38 Ma. This coincides with evidence for ice rafted debris and suggests input of organic matter via glacial processes. This also implies some continental glaciation occurred on East Greenland in the middle-to-late Eocene. Leaf wax hydrogen isotopes extending throughout this section – the first such long-term record from the Paleogene - indicate that precipitation δ2H was persistently higher than that of modern coastal Greenland, consistent with warmer ocean source waters and enhanced poleward moisture transport. Non-intuitively, however, this effect appears to have been smallest during the warmest part of the record, and higher δ2H values occur in the middle Eocene. Although interpretation of these hydrogen isotope trends is unclear, they clearly indicate – alongside the changes in biomarker abundances – a perturbed hydrological cycle through the Eocene in coastal Greenland. More long-term records are required to ascertain if this represents regional or global hydrological reorganisation.

Sea-level rise in Denmark: Bridging local reconstructions and global projections

Between 1850 and 2006 global mean sea level rose by 24 ± 18 cm. It is projected to rise a further 52 ± 21 cm under the Representative Concentration Pathway (RCP) 4.5 scenario, which approximates the carbon emissions reductions of the ‘Paris Agreement’ climate pathway. It is projected to rise 74 ± 28 cm under the RCP8.5 scenario, which represents a ‘business-as-usual’ climate pathway (Box & Colgan 2017). These rates of recent and future sea-level rise are faster than those reconstructed for previous warm intervals, such as the Medieval Climatic Optimum (c. 1000 to 1400 CE) and the Holocene Thermal Maximum (c. 7000 to 3000 BCE) (Gehrels & Shennan 2015). Moreover, palaeo reconstructions indicate a global sea-level sensitivity of two metres per degree of warming (Levermann et al. 2013).
 The forces driving global sea-level change are complex. The global sea-level budget includes the transfer of land ice into the ocean, thermal expansion of seawater, changes in land water storage, and changes in ocean basin volume (Church et al. 2013). At the local scale, the evolving planetary gravity due to shifting water and ice masses, shifting oceanic and atmospheric currents and persistent tectonic and glacial isostatic adjustment processes can also be important. Sea-level changes around the globe are therefore far from uniform (Jevrejeva et al. 2016).
 Here, we highlight the value of combining palaeo reconstructions of sea level, the measured tide gauge record, and projections of future sea level. This allows us to understand local sea-level changes from the recent past in the context of global projections for the near future (0 to 2100 CE). We explore the strong differences in local sea-level histories and future projections at three Danish cities: Skagen and Esbjerg, as they have contrasting glacio-isostatic adjustment histories, and Copenhagen, where we also compare local and global drivers of present-day sea-level rise based on previously published research.

Reconstructing the groundwater recharge history for the Plymouth-Carver Aquifer Massachusetts, USA

Groundwater systems can respond to climate forcing and millennial climate shifts more slowly than other components of the hydrologic cycle, making it difficult to reconstruct the influences and responses of groundwater to changing climate. Here, we test the linkage between climate change and groundwater responses by using water level changes situated in areas with permeable, unconfined aquifers systems. For hydroclimate histories, we compare moisture models from terrestrial water level reconstructions with predictions of available water from a transient earth system climate model. We focus our analysis on several small waterbodies with Holocene-era proxy measurements that are connected to the Plymouth-Carver glacial aquifer in southeastern Massachusetts, USA. Using these pond- and marsh-based records, we reconstruct groundwater recharge histories along individual groundwater flow paths using water level and sea level reconstructions with an analytical solution to the groundwater flow equation. We find that the water level reconstructions could contain both hydroclimate and sea level signals, with the early Holocene water levels primarily due to hydroclimate with predominantly a sea level signal after ∼7.5 ka cal BP. Our results indicate that sea level influenced coastal pond water levels, and sea level may play a more significant role than effective moisture over certain periods in the Holocene for terrestrial water bodies hydraulically connected to the evolving position of the coast. Future climate reconstructions developed from water level histories from low-elevation inland water bodies may benefit from examining the potential influence of sea level in addition to hydroclimate, but additional model validation and consideration of other cryosphere and glacial processes are needed to fully resolve sea level as a driver of terrestrial water level change.

Aquifer systems extending far offshore on the U.S. Atlantic margin

Low-salinity submarine groundwater contained within continental shelves is a global phenomenon. Mechanisms for emplacing offshore groundwater include glacial processes that drove water into exposed continental shelves during sea-level low stands and active connections to onshore hydrologic systems. While low-salinity groundwater is thought to be abundant, its distribution and volume worldwide is poorly understood due to the limited number of observations. Here we image laterally continuous aquifers extending 90 km offshore New Jersey and Martha’s Vineyard, Massachusetts, on the U.S. Atlantic margin using new shallow water electromagnetic geophysical methods. Our data provide more continuous constraints on offshore groundwater than previous models and present evidence for a connection between the modern onshore hydrologic system and offshore aquifers. We identify clinoforms as a previously unknown structural control on the lateral extent of low-salinity groundwater and potentially a control on where low-salinity water rises into the seafloor. Our data suggest a continuous submarine aquifer system spans at least 350 km of the U.S. Atlantic coast and contains about 2800 km3 of low-salinity groundwater. Our findings can be used to improve models of past glacial, eustatic, tectonic, and geomorphic processes on continental shelves and provide insight into shelf geochemistry, biogeochemical cycles, and the deep biosphere.

Deformation ‘boundary front’ movements in subglacial tills—A microsedimentological perspective from till sequences near Pine Point, NWT, Canada

AbstractInvestigations of glacial sediment exposures in a former open pit in the Pine Point Mining District, Northwest Territories, reveal evidence of changes in stress magnitude as exhibited by the movement of deformation ‘fronts’ within subglacial tills, as evident through micromorphological analysis. Indications of deformation, driven by stress fluctuations, were observed throughout a set of vertical subglacial till samples associated with the Laurentide Ice Sheet. These tills exhibit multiple sub‐lithofacies variations in concert with marked changes in microshear orientation, which can be directly related to changing stress levels within a subglacial deforming bed. The evidence of changes in till stress conditions is typical of subglacial tills occurring beneath an active temperate ice mass within a soft deforming bed. As differing ‘layers’ of till that form a mosaic‐like pattern become immobilized and ‘detached’ subjacent to the deforming bed sediments, a signature of this action is recorded within the tills as sequences of specific microstructures. These microstructures are part of a spectrum of micro‐forms that develop as consequence of changes in stress, porewater content and clay content within the ‘fault‐gouge’—like environment formed beneath an active temperate ice sheet. A model is developed that uses data from Pit O‐28 demonstrating where deformation ‘boundary front’ evidence in the form of deformation bands has developed as basal driven stress levels have penetrated active deforming sediments. The evidence from Pine Point indicates that till acts as an excellent palaeo‐strain record of past active glacial processes, subglacial basal thermal conditions and sediment mobility.

Working Out of Recommendations on Protection of the System of Artificial Snow Formation on the Slopes Elbrus Mount from Snow Avalanching

The Elbrus region is the most popular recreational complex of Kabardino-Balkar Republic and of the North Caucasus in general. In perspective in the Elbrus region it is supposed to create 32 aerial ropeways with total spread of 54 km and productivity of 67 thousand people per hour, and 62 ski slopes with total spread of 108 km and square of 506 hectares. It is supposed to realize complex exploration of north-eastern slope of Elbrus – Dzhili-Su region (mountain-recreational and therapeutic complex “Dzhili-Su”). A wide variety of orographic, geological, climatic and physical geographic conditions of the mountainous part of Kabardino-Balkaria predetermine an active development of natural disasters on its recreational territories. The regions of location of existing and newly-created different routes and mountain-recreational complexes on the slopes of Elbrus due to their specific geographical position and natural conditions, are under the influence of dangerous glacial processes, in particular, snow avalanching. The area of the object projection “Reconstruction of artificial snow formation system, Elbrus mount” is also avalanche-risk one.

Processes and patterns of glacier-influenced sedimentation and recent tidewater glacier dynamics in Darbel Bay, western Antarctic Peninsula

AbstractBathymetric data of unprecedented resolution are used to provide insights into former ice dynamics and glacial processes in a western Antarctic Peninsula embayment. An assemblage of submarine glacial landforms, which includes subglacially produced streamlined features and ice-marginal ridges, reveals the former pattern of ice flow and retreat. A group of more than 250 small (< 1–3 m high, 10–20 m wide) and relatively evenly spaced recessional moraines was identified beyond the margin of Philippa Glacier. The small recessional moraines are interpreted to have been produced during short-lived, possibly annual re-advances of a grounded ice margin during overall retreat. This is the first time that these features have been shown to be part of the assemblage of landforms produced by tidewater glaciers on the Antarctic Peninsula. Glacier-terminus changes during the last four decades, mapped from LANDSAT satellite images, were analysed to determine whether the moraines were produced during recent still-stands or re-advances of Philippa Glacier and to further investigate the short-term (annual to decadal) variability in ice-marginal position in tidewater glacier systems. The asynchronous response of individual tidewater glaciers in Darbel Bay is interpreted to be controlled mainly by local topography rather than by glacier catchment-area size.

Glacier dynamics during a phase of Late Quaternary warming in Patagonia reconstructed from sediment-landform associations

The geomorphological record in glaciated landscapes can provide important information for the study of the response of glaciers to rapid climate change. This study presents a new reconstruction of the glacial history of the northern Monte San Lorenzo ice cap, southern South America, during a period of accelerated warming and deglaciation following the Antarctic Cold Reversal (14.5–12.8 ka). We present a detailed geomorphological map of the valleys to the north of Monte San Lorenzo. Sediment-landform assemblages identified include lateral and terminal moraine ridges, flutes, deltas, ice-contact fans, palaeoshorelines, kame terraces and outwash plains. We map 14 primary ice-limits, 7 of which are newly identified, and 7 of which are from previous studies, mapped here in greater detail. We devise landsystem models to formalise and document spatial and temporal changes in glacial processes and environments. Our new geomorphological mapping and landsystem reconstructions provide an important insight into the response of temperate Patagonian glaciers to rapidly-warming climate.

A slippery slope for Cryogenian diamictites?

AbstractThe Death Valley region has previously been claimed to preserve the sedimentary records of both the Sturtian and Marinoan snowball Earth events within the Kingston Peak Formation, which outcrops in a number of disconnected mountain ranges. In this context, new sedimentary logs are presented together with detailed clast textural analyses which allow diamictites of the Alexander Hills and the Saddle Peak Hills to be compared in detail for the first time, and to be contrasted with rocks of well‐established glaciogenic origin from the Kingston Range. Notably, in the Saddle Peak Hills, clasts identical in composition and facies to that of the Noonday Dolomite—a unit previously interpreted as the post‐Marinoan cap carbonate—are incorporated into diamictites at the top of the Kingston Peak Formation. Combined with the carbonate‐rich composition of rocks at the top of the formation, these observations suggest that the uppermost diamictites of the Saddle Peak Hills and Alexander Hills are genetically related to the Noonday Dolomite and are unrelated to glacial processes. We propose that they formed through local slope foundering and basinward collapse of the adjacent carbonate platform, substantiating recent interpretations of Noonday carbonate platform dynamics, and demonstrating that they are genetically unrelated to Cryogenian glaciation. Thus, clast textural analyses play a valuable role in establishing whether contested ‘snowball Earth’ outcrops are truly glaciogenic or simply the product of local slope collapse.

Correction to: Effects of temperature and salinity on the reproductive phases of Macrocystis pyrifera (L.) C. Agardh (Phaeophyceae) in the Magellan region

The region of Magallanes has the world’s largest sub-Antarctic environments, including the heterogeneous habitats of archipelagos, fjords, channels, and inlets formed by ice advancing and retreating during Quaternary glacial processes. In marine ecosystems, the temperature, salinity, and photoperiod are key parameters which delimit the survival, reproduction and development of the macroalgae and, therefore, the biogeography of numerous sub-Antarctic species. In this research, we compare the reproductive development patterns in spores of Macrocystis pyrifera coming from places with different salinities along longitudinal and latitudinal gradients in Skyring Sound, Otway Sound, the Strait of Magellan (Possession Bay and Puerto del Hambre), and the Beagle Channel (Paula Bay). Laboratory analyses included four salinities and two different temperatures, comparing the percentage of spore germination, sex ratio in females and male gametophytes, and the development of gametogenesis through the proportion of gametophytes and sporophytes, with a factorial experimental design. The best germination percentages were obtained in Puerto del Hambre; the best sex ratio, on the other hand, was in Skyring Sound; finaly, for gametogenesis development, the best results were obtained in Otway Sound and Possession Bay. We prove the temperature and salinity effect over the studied population; moreover, these results demonstrate that at the end of the cycle each population develops more effectively in their local conditions, evidence of a local adaptation in M. pyrifera populations living in contrasting sites in the same region. This is crucial to understand how these populations react to the effect of environmental stressors; furthermore, the selection of appropriate conditions is also an important factor for the future commercial cultivation management of these important macroalgae.

Morphometric evidence of 3.6 Ga glacial valleys and glacial cirques in martian highlands: South of Terra Sabaea

The climate of early Mars remains unclear and the debate is topical. Recently, climatic models have suggested a cold climate during the Noachian/Early Hesperian on Mars, which goes against the wet and warm climate often put forward. The purpose of this study is to seek geomorphologic evidence of this early cold climate. To achieve this, a step-by-step study of the geometry and morphology of several martian valleys has been done in the southern highlands. The analysis highlights the morphometric properties which enable the identification of martian glacial landscapes. We identified 100 cirques and 83 glacial valleys in two craters and on one mountain in the southern part of Terra Sabaea. The studied morphologies have the same morphometric characteristics and trends as terrestrial and martian glacial valleys and glacial cirques. In contrary, these trends are very different from those observed in fluvial valleys on Earth and on Mars. (1) The martian glacial valleys are U-shaped with a large flat floor and a V-index >0.20. While martian and terrestrial fluvial valleys are V-shaped with a V-index <0.1. (2) The length to width ratio is >1 while for fluvial valleys this ratio is ≫1. (3) Finally, the cross-sectional area and the elevation are higher for the glacial valleys compared to the fluvial ones. These glacial valleys often originate with a topographic hollow which have the same properties than terrestrial glacial cirque. The glacial landscapes identified in southern Terra Sabaea are restricted to elevations >1000 m and are dated by crater counting to be 3.6 Ga. This study strongly supports glacial processes as the origin of these valleys and cirques, and is the first morphometric evidence of glacial valleys associated with glacial cirques in the southern highlands in agreement with the climatic models. We propose that the martian climate during the late Noachian/early Hesperian was characterized by glaciated highlands at elevations >1500 m and at lower elevations where fluvial valley network has been identified (<1500 m) the climate was more temperate allowing liquid water to be stable and creating fluvial valley networks.

Paraglacial adjustment of alluvial fans to the last deglaciation in the Snežnik Mountain, Dinaric karst (Slovenia)

Glaciokarst depressions are major glacigenic depocenters in the Dinaric mountain karst areas and often store important information about the timing and nature of glacial processes and paraglacial sediment reworking. This study focuses on Praprotna draga, which is one of the largest glaciokarst depressions in the Snežnik Mountain (Dinaric karst), with an area of ~3.4 km2 and a maximum depth of 140 m. The western slopes of the depression are characterized by undulated moraine morphology and alluvial fans are filling its entire floor. We present the results on the thickness, origin and age of the sediment infill using a complementary geomorphological, sedimentological, geophysical and dating approach. Distribution of moraines point to two glacial advances that were associated with two main alluvial fan aggradation phases recognized using the electrical resistivity tomography measurements. The youngest alluvial deposits were sampled for cosmogenic 36Cl analysis using amalgamated carbonate pebbles. The depth profile of 36Cl concentrations suggests an age of 12.3 ± 1.7 ka when assuming a likely denudation rate of 20 mm ka−1. Since the existence of the Younger Dryas glaciers in the study area is climatically difficult to explain, we tentatively propose that the youngest alluvial deposition in Praprotna draga took place after the glacier retreat during the paraglacial period. Our findings suggest that the time window of paraglacial adjustment in the Snežnik Mountain was brief and likely conditioned by quick recolonization with vegetation and inefficient surface runoff on deglaciated karst terrain.

An introduction to glaciated margins: the sedimentary and geophysical archive

Abstract A glaciated margin is a continental margin that has been occupied by a large ice mass, such that glacial processes and slope processes conspire to produce a thick sedimentary record. Ice masses take an active role in sculpting, redistributing and reorganizing the sediment that they erode on the continental shelf, and act as a supply route to large fan systems (e.g. trough mouth fans, submarine fans) on the continental slope and continental rise. To many researchers, the term ‘glaciated margin’ is synonymous with modern day areas fringing Antarctica and the Arctic shelf systems, yet the geological record contains ancient examples ranging in age from Precambrian to Cenozoic. In the pre-Pleistocene record, there is a tendency for the configuration of the tectonic plates to become increasingly obscure with age. For instance, in the Neoproterozoic record, not everyone agrees on the location of rift margins and some fundamental continental boundaries remain unclear. Given these issues, this introductory paper has two simple aims: (1) to provide a brief commentary of relevant Geological Society publications on glaciated margins, with the landmark papers highlighted and (2) to explain the contents of this volume.

Little Ice Age glacial systems and related natural instability processes in the Orco Valley (North-Western Italy)

ABSTRACT Glaciated and recently (post-Little Ice Age) deglaciated areas are very dynamic environments, undergoing continuous changes, in particular as a consequence of climatic fluctuations and cryosphere changes. The intense geomorphic activity that takes place here conditions natural hazard, sediment transport and tourist fruition. A geo-morphological mapping with applicative purposes has to take into account the peculiarities and the dynamism of these specific areas. We here propose a methodological approach based on the interpretation of a multitemporal set of aerial photos (from 1983 to 2012), in a GIS environment, with application to the sectors modeled by Little Ice Age glaciers in the upper Orco Valley (NW Italy). The result is a geo-morphological map focused on the elements that are most relevant for application purposes, complemented by a map of the spatio-temporal distribution of the natural instability processes identified in the study area for the reference period, aimed to highlight the recent dynamism of the geomorphological elements in the map.

Latitudinal trends in modern fluvial erosional efficiency along the Andes

Latitude is a dominant control on climate, influencing both temperature and precipitation, leading to potential gradients in erosional efficiency. Previous work focused on the latitudinal control of glacial erosion on topography; however, the expected latitudinal trend in erosional efficiency in the absence of glacial processes is unknown. We parameterize a suite of numerical models using uniform rock-uplift and climate from the Andes to explore how latitudinal patterns of rainfall could influence the efficiency of fluvial bedrock erosion. We use the CHILD landscape evolution model parameterized with storm duration, intensity and frequency statistics from NCEP/NCAR Reanalysis data along the Andes over 31 years to predict latitudinal trends in topography subject only to fluvial and hillslope erosion. Modeled elevations, as a metric for erosional efficiency, vary 2–30 fold depending on the erosional and hydrological model parameterization. Modeled elevation trends generated using stochastic storm generation vary significantly from those generated using mean annual precipitation (MAP). The variation suggests MAP may not capture the true erosional efficiency of the modern climate in some locations, but may in others, explaining the discrepancy of conclusions in previous studies. Erosional efficiency is greatest in the tropics (5–15°S) where high intensity and frequent storms occur and mid-latitudes (30–35°S) where less frequent but intense storms occur. Erosional efficiency is lowest in the subtropics (20 to 25°S) where low intensity and infrequent storms occur and upper-mid-latitudes (45–50°S) where low intensity and somewhat frequent storms occur. Erosional efficiency varies across the width of the orogen because of across-orogen effects. The results provide further evidence supporting climate's control on erosion processes and topography, highlighting the importance of stochastic storm distributions and suggesting that latitudinal controls on rainfall can explain some observed trends in topography. The modern latitudinal trend in topography is frequently used as an argument for a glacial buzzsaw; however, our results suggest more information on the pre-glacial distribution of topography is needed to justify such an argument since latitude dependent rainfall regimes may generate similar topographic trends.

Geomorphic processes influence human settlement on two islands in the Islands of Four Mountains, Alaska

AbstractThe Islands of Four Mountains island group of the Aleutian island arc is remote and difficult to access. Consequently, little fieldwork has focused on geomorphic processes and their relationship to island morphology, climatic change, and human settlement. We investigated glacial, fluvial, and slope processes on the morphologically different Carlisle, Cleveland, and Tana volcanoes. The islands were extensively glaciated at the last glacial maximum (LGM), and there is evidence for a Neoglacial advance. On the highly dissected Tana volcano, a large basin is likely the result of a pre-LGM sector collapse and subsequent glacial erosion into weak hydrothermally altered rock. Valley and moraine morphology is also influenced by hydrothermal alteration. On both Tana and Carlisle, there are sediment fans composed dominantly of thick debris flow deposits mantled by ~3 m of layered tephras, fine-grained alluvium, and anthropogenic deposits. Debris flow deposition was favored during the unstable paraglacial landscape of the early Holocene–latest Pleistocene. The earliest direct archaeological evidence for settlement is 3.8 cal ka BP, but soil geochemical evidence suggests that the islands were inhabited by 7.3 cal ka BP. This discrepancy in the archaeological record may be explained by geomorphic processes including coastal erosion and unstable geomorphic surfaces.

Effects of temperature and salinity on the reproductive phases of Macrocystis pyrifera (L.) C. Agardh (Phaeophyceae) in the Magellan region

The region of Magallanes has the world’s largest sub-Antarctic environments, including the heterogeneous habitats of archipelagos, fjords, channels, and inlets formed by ice advancing and retreating during Quaternary glacial processes. In marine ecosystems, the temperature, salinity, and photoperiod are key parameters which delimit the survival, reproduction and development of the macroalgae and, therefore, the biogeography of numerous sub-Antarctic species. In this research, we compare the reproductive development patterns in spores of Macrocystis pyrifera coming from places with different salinities along longitudinal and latitudinal gradients in Skyring Sound, Otway Sound, the Strait of Magellan (Possession Bay and Puerto del Hambre), and the Beagle Channel (Paula Bay). Laboratory analyses included four salinities and two different temperatures, comparing the percentage of spore germination, sex ratio in females and male gametophytes, and the development of gametogenesis through the proportion of gametophytes and sporophytes, with a factorial experimental design. The best germination percentages were obtained in Puerto del Hambre; the best sex ratio, on the other hand, was in Skyring Sound; finaly, for gametogenesis development, the best results were obtained in Otway Sound and Possession Bay. We prove the temperature and salinity effect over the studied population; moreover, these results demonstrate that at the end of the cycle each population develops more effectively in their local conditions, evidence of a local adaptation in M. pyrifera populations living in contrasting sites in the same region. This is crucial to understand how these populations react to the effect of environmental stressors; furthermore, the selection of appropriate conditions is also an important factor for the future commercial cultivation management of these important macroalgae.

The engineering properties of glacial tills

Glacial tills are a product of the glacial processes of erosion, transportation and deposition and could have been subjected to several glacial cycles and periglacial processes to the extent that they are complex, hazardous soils that are spatially variable in composition, structure, fabric and properties, making them very difficult to sample, test and classify. An overview of the formation of glacial tills and their properties shows that they are composite soils which should be classified according to their lithology, their mode of deposition to link the glacial processes with the facies characteristics and their engineering behaviour. This enables representative design properties to be assigned using frameworks developed for composite soils.

Quaternary structural and paleo-environmental evolution of the Alpine Fault near Haast, New Zealand, from 2D seismic reflection and gravity data

ABSTRACTThe geometry of the upper-crustal portion of the Alpine Fault plate boundary on New Zealand’s South Island, is poorly constrained where it cuts through the sedimentary units of the Westland coastal plain. Two seismic reflection and gravity lines are presented here to better image the upper km of the fault beneath the most recent fault rupture scarps south of the Haast River. Analysis of the seismic lines suggests that multiple fault strands have cut across post-glacial sedimentary strata that overlie the glacially eroded basement. Total combined fault offsets of 39 m at the Haast River and 33 m at the Turnbull River over <17 ka is consistent with previously determined uplift rates. Dip on the fault strands is interpreted to be between ∼53 and ∼76° SE. 2D gravity profiles constrain the interpretation of the interface between sedimentary units and basement, which has considerable 3D variability resulting from glacial erosion processes.

Late Quaternary Palaeoclimate and Contemporary Moisture Source to Extreme NW India: A Review on Present Understanding and Future Perspectives

The trans-Himalayan region of NW India along with western part of Tibet, Karakoram,and Hindukush range is hosting thousands of glaciers ensuring perennial freshwater supply to the Indian subcontinent and supporting a large fraction of the global population. The peculiar physiography not only limits the entry of water enriched Indian Summer Monsoon winds to this region but also give passage to dry winds of barren desert of Taklamakan, the Aksai Chin,and western Tibet, making it a cold desert. The Quaternary glacial and interglacial phases govern the present geomorphological setup of the region, wherein the glacial process designed the basic framework, which subsequently modified by the fluvial-lacustrine-aeolian processes.Over the years, our understanding in drawing climatic inferences from the sedimentary archives has improved significantly. However, the discrepancy in chronological results among and within different dating techniques is posing a serious challenge. Since the region is experiencing cold desertic climate and being in the rain shadow zone of the Indian Summer Monsoon (ISM), earlier studies show that the major source of moisture received by the Mediterranean Sea.However, the recent isotopic study of the Indus river water along with other major tributaries and minor streams, it is concluded that ISM source is equally important supplier of the moisture in the Ladakh region of NW India.