monsoon fluctuations in two 20 000 yr b p oxygen isotope pollen records off southwest india abstract two marine pollen diagrams for sediments off the southwest coast of india provide a 20 000 yr history of the nearby continental vegetation determined by the monsoon climate within the framework of the isotopic stratigraphy two important phases of the evolution of the monsoon climate are a very arid period about 22 000 18 000 yr b p and a very humid period culminating at 11 000 yr b p the very arid period corresponds to the lowest pollen representation of mangrove vegetation which is used here as an indirect indicator of monsoonal runoff this aridity is due to a very weak southwest airflow a great reduction of summer monsoonal rainfall and reduced runoff of the western ghats rivers the extension of the monsoon over india after the last glacial maximum has been a gradual process following the northward progression of the intertropical convergene zone the very humid period corresponding to the highest pollen representation of mangrove vegetation and the heaviest summer rainfall is a climatic response to the maximum summer insolation of the northern hemisphere at 11 000 yr b p

variability of arctic sea ice topography and its impact on the atmospheric surface drag over the polar oceans near surface atmospheric transport of momentum is strongly influenced by sea ice surface topography the latter is analyzed on the basis of laser altimeter data obtained during airborne campaigns between 1995 and 2011 over more than 10 000 km of flight distance in different regions of the arctic ocean spectra of height and spacing between topographic features averaged over 10 km flight sections show that typical values are 0 45 m for the mean height and about 20 m for the mean spacing nevertheless the variability is high and the spatial variability is stronger than the temporal one the total topography spectrum is divided into a range with small obstacles between 0 2 m and 0 8 m height and large obstacles 0 8 m results show that large pressure ridges represent the dominant topographic feature only along the coast of greenland in the central arctic the concentration of large ridges decreased over the years accompanied by an increase of small obstacles concentration and this might be related to decreasing multiyear ice the application of a topography dependent parameterization of neutral atmospheric drag coefficients reflects the large variability in the sea ice topography and reveals characteristic differences between the regions based on the analysis of the two spectral ranges we find that the consideration of only large pressure ridges is not enough to characterize the roughness degree of an ice field and the values of drag coefficients are in most regions strongly influenced by small obstacles

tectono climatic signatures during late quaternary in the yunam basin baralacha pass upper lahaul valley india derived from multi proxy records abstract this study provides evidence of the monsoon record over the past 25 ka from the kilang sarai palaeolake which is located in nw himalaya in the rain shadow zone of the indian summer monsoon ism the multi proxy study by using geomorphology carbon isotopes mineral magnetism clay mineralogy and elemental chemistry of a 8 m thick laminated lacustrine sediments indicates that the area experienced fluctuating precipitation conditions during the last 25 ka the time period between 12 and 5 ka bp can be regarded as a very wet interval of the last glacial to mid holocene due to a combined effect of ism and westerlies followed by aridity after 5 ka bp tectonic triggers may have caused the development of terraces and closure of lake at the millennial time scale a correlation of precipitation and vegetational changes between our data and other records from similar geographical settings suggests that kilang sarai basin responded to periods of strengthening in precipitation during the last glacial to early holocene

tectonic forcing of longitudinal valleys in the himalaya morphological analysis of the ladakh batholith north india abstract longitudinal valleys form first order topographic features in many mountain belts they are commonly located along faults that separate tectonic zones with varying uplift histories the indus valley of ladakh northern india runs northwestwards following the boundary between the relatively undeformed ladakh batholith to the north east and the folded and thrusted zanskar mountains to the south west in this region the shyok valley on the northern side of the batholith approximately parallels the course of the indus this study investigates geomorphic variations in transverse catchments that drain the ladakh batholith into the indus and shyok rivers the batholith has been divided into three zones based on varying structural characteristics of its northeastern and southwestern boundaries morphometric analysis of 62 catchments that drain into the indus and shyok valleys was carried out using three digital datasets and supported by field observations morphometric asymmetry is evident in the central zone where the shyok valley is considered tectonically inactive but the indus valley is bound by the northeastwardly thrusting indus molasse and the batholith in this zone the catchments that drain into the indus valley are more numerous shorter thinner and have lower hypsometric integrals than those that drain into the shyok by linking these observations with the regional geology and thermochronological data it is proposed that high sediment discharge from the deformed indus molasse indus valley has progressively raised base levels in the indus valley and resulted in sediment blanketing of the opposing tectonically quiescent catchments that drain southwestwards off the batholith the indus molasse thrust front has propagated at least 36 km towards the ladakh batholith over the last 20 ma hence it is proposed that this long term asymmetric structural deformation and exhumation has forced the indus longitudinal valley laterally into the ladakh batholith resulting in the morphometric asymmetry of its transverse catchments

unconfined flow deposits in distal sectors of fluvial distributary systems examples from the miocene luna and huesca systems northern spain abstract thin sheet sandstone beds in a continental succession may be the products of unconfined overbank flow or deposition in lacustrine environments in the distal parts of fluvial distributary systems these two settings may be intercalated recording fluctuations in lake level in response to climatic changes field studies of the luna and huesca fluvial distributary systems in the miocene of the ebro basin spain are here used to characterise sheet sandstone deposited in distal fluvial and lake margin environments in this study we document the facies and relationships between 322 individual sandbodies deposited in both alluvial settings as sheetfloods and in lacustrine settings as deltaic lobes the alluvial sandstone sheets were deposited from lateral and frontal sheetflood events when unconfined flow replaced channelised flow as the main transport mechanism the term sheetflood is used here to refer to sub aerial unconfined turbulent flow events that undergo expansion thinning and deceleration with increasing radial distance from source the depositional process is similar to modern floodouts and terminal splays of the channel country and lake eyre central australia such a process was thought to be the dominant depositional mechanism during lake lowstands the sheets formed in the lacustrine setting are interpreted as deltaic sediments deposited in a shallow gradient lake similar to the modern day volga delta caspian sea shallow water friction dominated deltaic processes are thought to have been the primary depositional mechanism in the distal sectors of the fluvial systems during lake highstands

climatic variations and geomorphology of the indus river valley between nimo and batalik ladakh nw trans himalayas during late quaternary abstract the indus river valley is tectonically unstable exhibiting complex topography landscape relief and varied sedimentation the major geomorphic landforms are alluvial fans debris cones fluvio lacustrine deposits scree and talus cones in the present work a transect between nimo and batalik along the river was studied to consider the geomorphological landform evolution during the quaternary based on the distribution of the sediments along the valley mass movements catastrophic land sliding and tectonic activity transported material from steep slopes to valley bottoms which were responsible for forming lakes preserved as thick piles of fine sediment while the outburst floods redistributed sediment down valley three phases of lake formation are recorded in the 136 km stretch 35 000 26 000 bp lamayuru palaeolake 17 000 13 000 bp rizong palaeolake occupying 35 km of the valley length and 14 000 5000 bp khalsi saspol palaeolake 55 km in length and having the highest lake levels the lake formation is attributed to deglaciation after the last glacial maximum lgm and holocene warming tectonic activity seismites are concentrated only at 10 and 6 ka

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

airborne observations of summer thinning of multiyear sea ice originating from the lincoln sea to better understand recent changes of arctic sea ice thickness and extent it is important to distinguish between the contributions of winter growth and summer melt to the sea ice mass balance in this study we present a lagrangian approach to quantify summer sea ice melt in which multiyear ice myi floes that were surveyed by airborne electromagnetic thickness sounding within nares strait during summer were backtracked using satellite imagery to a region in close proximity 3 20 km to spring ice thickness surveys carried out in the lincoln sea typical modal total myi thicknesses including 0 4 m snow ranged between 3 9 and 4 7 m in the lincoln sea during april ice only modal thicknesses were between 2 2 and 3 0 m in nares strait during august total thinning including snow and ice was 1 3 0 1 m including 0 4 0 09 m of snow melt and 0 9 0 2 m of ice melt this translates to a seasonal net heat input of 305 69 mj m2 262 60 mj m2 for ice only and seasonal net heat flux of 57 13 w m2 45 10 w m2 for ice only which is unlikely to be explained by solar radiation fluxes alone furthermore our approach provides an improvement on traditional ice mass balance buoy estimates because it integrates melt over larger spatial scales where melt can be highly variable due to differential melt experienced between melt ponds bare ice hummocks and ridges

soil carbon isotope evidence for holocene habitat change in the kenya rift valley in eastern africa the altitude of the boundary between montane forest and lowland savanna grassland changed substantially in response to climate change during the later holocene but this is not clearly reflected in regional pollen records the carbon 13 to carbon 12 ratios of tropical grasses are higher than those of most other plants and this difference is preserved in soil organic carbon stable isotope ratios soil organic matter 13 c 12 c ratios in profiles along an altitude transect in the central rift valley of kenya suggest that the forest savanna boundary advanced more than 300 meters in altitude this could have implications for understanding the effects of climate change on the configuration of floral zones prehistoric hunter gatherer land use patterns and the timing of the advent of neolithic food production

palaeoclimatic significance of magnetic properties from late quaternary lacustrine sediments at pithoragarh kumaun lesser himalaya india abstract mineral magnetic studies were carried out on lacustrine deposits from pithoragarh palaeolake kumaun lesser himalaya india these deposits have already provided valuable information for the reconstruction of palaeoclimatic changes and tectonic uplift in the himalayan region according to radiocarbon chronology the lake existed from 35 to 10 kyr bp using magnetic data radiocarbon ages and lithology the top of the well studied 13 m thick wadda section can be correlated to the basal part of the 4 7 m thick riyasi section fuzzy c means cluster analysis using only magnetic parameters enables a subdivision of the riyasi section into five magnetic zones based on three clusters these clusters are related to the relative contribution of the various magnetic constituents i e coarse hem c and ultrafine hem f grained hematite both showing relatively soft magnetic behaviour for the lowermost three zones existing pollen data from the wadda section helps to establish the climatic implications of the magnetic clusters and zones the model is as follows during humid periods magnetic mineralogy is mainly controlled by hem f formed in situ whereas during colder and more arid conditions detrital input of hem c and also hem f from the catchment area predominates climatic interpretation for the upper part of the section is attempted on the basis of the magnetic data but has to be confirmed by further pollen studies

surface roughness of baltic sea ice small medium and large scale measurements of sea ice surface roughness were carried out in the baltic sea over a 3 year period a clear relationship was found between the rms height and correlation length of baltic sea ice in most cases the surface correlation function was close to exponential the logarithm of rms height showed a linear dependence on that of measured distance similarly the correlation length was in many cases linearly dependent on the measured distance this dependence on length suggests that ice surface roughness could be characterized as a fractal

vegetation and climate during the last 30 000 years in ladakh abstract pollen analysis was carried out from a 23 m core dating from about 30 000 to 9000 yr b p from the alpine tsokar lake about 4572 m above sea level in ladakh trans himalayan region this study reveals the continuation of the alpine steppe with four periods of expansion of juniperus communities during 28 000 30 000 yr b p 21 000 18 375 yr b p slightly before 15 800 yr b p and at 10 000 yr b p these phases of juniperus expansion were interpreted as events of amelioration of climate within the alpine steppe during the later part of the last weichselian glaciation in the alpine trans himalayan region

the roughness of natural terrain a planetary and remote sensing perspective we examine the various methods and parameters in common use for quantifying and reporting surface topographic roughness it is shown that scale dependent roughness parameters are almost always required though not widely used we suggest a method of standardizing the parameters that are computed and reported so that topographic data gathered by different workers using different field techniques can be directly and easily intercompared we illustrate the proposed method by analyzing topographic data from 60 different surfaces gathered by five different groups and examine the information for common features we briefly discuss the implications of our analysis for studies of planetary surface roughness lander safety and radar remote sensing modeling and analysis

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

early holocene monsoonal fluctuations in the garhwal higher himalaya as inferred from multi proxy data from the malari paleolake abstract a 4 9 m thick lake sequence formed due to the landslide damming of a stream in the semiarid garhwal himalaya was studied to understand past monsoonal variations in the region the optically stimulated luminescence osl chronology indicates that the lake existed between 12 and 7 ka ago chronologically constrained trends of sand percent organic phosphorus op apatite inorganic phosphorus aip and parameters of environmental magnetism were measured in the paleolake profile measured proxies indicate that the indian summer monsoon ameliorated in the early holocene after 12 ka cooling and it appears that all the proxies from the lake have captured this globally recognized early holocene warming four phases of wet conditions intensified monsoon are recognized at 11 5 ka 11 10 5 ka 10 9 ka and 8 7 ka with maximum uncertainties of 1000 years the wet phases are characterized by high magnetic susceptibility increased op and reduced aip in an attempt to understand the primary forcing of the sharp fluctuations in monsoonal activity in the region we show that changes in magnetic susceptibility match variations of residual atmospheric 14c suggesting a role for solar variability as an explanation of climatic variability

palaeoclimatic conditions in the upper pleistocene and holocene bhimtal naukuchiatal lake basin in south central kumaun north india abstract a 52 m thick upper pleistocene and holocene terrestrial succession in the bhimtal naukuchiatal basin south central kumaun himalaya india was studied using chronological palaeontological palynological and 13c measurements the section recorded evidence for climatic changes at least two phases of arid climate and one phase of humid climate were recognised preliminary palaeomagnetic studies revealed a reversal of polarity presumably correlatable with the mono lake excursion prior to this no reversal event in the upper pleistocene holocene terrestrial sediments of indian subcontinent is known a fossiliferous horizon discovered in the lower part of the section consisted of sorex and mus this is the only report of a late pleistocene micromammalian assemblage in the kumaun himalaya

a genetic model of thrust bounded intermontane basin using scaled sandbox analogue models an example from the karewa basin kashmir himalayas india the himalayan mountain system has many depressions of regional dimensions which are found oriented mostly e w to ne sw mainly to the north of the main boundary fault mbf the karewa basin in the kashmir himalaya has sediments belonging to late neogene to quaternary formations which represent an almost 1 300 m thick succession of sand mud and gravels exposed in the river valleys and the plateau margins of the entire kashmir valley sandbox analogue experiments show a great variety of wedge shapes showing significant changes in the taper angles due to the change in basal friction between two pop ups or depressions pop down of significant dimensions develop along the strike of the growing wedge in order to maintain the critical angle these depressions initially receive material from the hinterland and later on from the foreland end of the wedge the depressions have developed due to the change in the surface slope of the wedge and receive the eroded material only from the adjacent upheaved portions of the wedge on continuation of the experiments in cases where the wedge is highly unstable these depressions are coupled with the wedge along with their sand fills the depositional history of the karewa sediments indicates a sequential evolutionary pattern of the basin and thus represents a natural analogue of the sandbox experiments

combined observations of arctic sea ice with near coincident colocated x band c band and l band sar satellite remote sensing and helicopter borne measurements in this study we compare colocated near coincident x c and l band fully polarimetry sar satellite images with helicopter borne ice thickness measurements acquired during the norwegian young sea ice 2015 n ice2015 expedition in the region of the arctic ocean north of svalbard in april 2015 the air borne surveys provide near coincident snow plus ice thickness surface roughness data and photographs this unique data set allows us to investigate how the different frequencies can complement one another for sea ice studies but also to raise awareness of limitations x band and l band satellite scenes were shown to be a useful complement to the standard sar frequency for sea ice monitoring c band for lead ice and newly formed sea ice identification this may be in part be due to the frequency but also the high spatial resolution of these sensors we found a relatively low correlation between snow plus ice thickness and surface roughness therefore in our dataset ice thickness cannot directly be observed by sar which has important implications for operational ice charting based on automatic segmentation

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

hydrological evolution during the last 15 kyr in the tso kar lake basin ladakh india derived from geomorphological sedimentological and palynological records abstract the tso kar lake basin in ladakh northwestern himalayas 33 18 n 78 e 4527 m a s l is located close to the modern boundary of effective moisture transport from the indian summer monsoon in order to reconstruct the possible monsoonal impact on the hydrology of the lake basin during the last 15 kyr we studied the geomorphology of the basin and combined the results with multi proxy records from tso kar lake sediments major analyses comprise geochemical data high resolution x ray fluorescence xrf mineral composition xrd aquatic pollen and non pollen palynomorphs npp although the chronological framework based on 41 14c ams dates remains speculative for the lateglacial and late holocene periods our results indicate major hydrological phases linked to regional climate variations and tectonic activity the maximum glacier advance falls within the period between the global lgm and ca 15 kyr bp while the basin remained open and may have drained along the paleo tso kar river tectonic pulses may have triggered terrace development and the closure of the lake the estimated mean vertical displacement rate accounts for 7 9 mm yr considerable summer monsoon moisture supply occurred for the periods around 12 5 kyr bp and between ca 11 5 and 8 6 kyr bp indicated by deposition of more profundal lake facies and the development of aquatic fauna and flora the lake level rise about 11 8 kyr bp was due to intensified glacier melt and summer monsoon effective moisture supply the lake reached its maximum level and extent between 8 5 and 7 kyr bp under warm moist climate conditions permafrost was absent from the basin summer monsoon influence weakened after 8 kyr bp with a short reverse trend at ca 5 6 kyr bp the lake shrank gradually after 7 kyr bp towards its lowest stand at about 4 2 kyr bp with return of permafrost activity subsequent terrace formation was probably amplified by tectonic movement the lake remained at a low level with minor fluctuations the results indicate that the orbitally driven regional climate variability is well reflected in the tso kar basin by hydrological variations considerable summer monsoon moisture seems to have influenced the area only during the early holocene the late quaternary evolution of the tso kar was controlled by the interplay of climate forces local morphodynamics and tectonic impact

quaternary fluvio lacustrine deposits of the lamayuru basin ladakh himalaya preliminary multidisciplinary investigations preliminary multidisciplinary investigations were carried out in a 105 m thick late pleistocene terrestrial sequence in the lamayuru basin ladakh himalaya palaeomagnetic studies reveal a reversal of polarity at about 35 ka bp this is the only report of this reversal event in the late pleistocene terrestrial sequences of the indian subcontinent the valley fill sequence is the product of an interplay of lacustrine with fluvio deltaic to colluvial processes four fossiliferous horizons have yielded ostracods and gastropods indicating shallow freshwater conditions the lamayuru lake was created by tectonically induced instabil ity about 35 40 ka bp an event that may be represented widely throughout the himalaya

quantitative roughness characterization of geological surfaces and implications for radar signature analysis stochastic surface models are useful for analyzing in situ roughness profiles and synthetic aperture radar sar images of geological terrain in this paper two different surface models are discussed surfaces with a stationary random roughness conventional model and surfaces with a power law roughness spectrum fractal model in the former case it must be considered that for short profiles l 200l sub 0 the measured values of rms height s and correlation length l may be significantly smaller than the intrinsic values s sub 0 and l sub 0 in the latter case rms height and correlation length depend on the profile length l and the surface is better characterized by slope and offset of the roughness spectrum which are independent of l the sensitivity of the sar signature to variations in surface roughness parameters is evaluated by means of theoretical scattering models for smoother geological surfaces such as most arid terrain types single scattering is dominant which means that the roughness parameters can be determined from sar data using comparatively simple algorithms multiple scattering processes on rough surfaces such as a a lava and variations of the local incidence angle due to large scale terrain undulations make the retrieval of roughness parameters by means of inverse modeling much more complex field data of surface roughness indicate that rougher geological surfaces may be in the diffractal regime at higher radar frequencies in which the scattering characteristics deviate significantly from the patterns observed for stationary surfaces on the basis of surface and scattering models recently published observations of roughness data and radar signatures from volcanic alluvial and arid surfaces are examined

soft sediment deformation structures in the late quaternary sediments of ladakh evidence for multiple phases of seismic tremors in the north western himalayan region abstract the exposed quaternary sections of ladakh show evidence of seismicity during the late quaternary multiple levels of soft sediment deformation structures seismites are recorded from the quaternary sediments of the spituk leh along indus suture zone isz and the khalsar palaeolakes along shyok suture zone ssz and karakoraum fault kf the studied sections are a part of two major tectonically formed palaeolakes at 35 000 yr bp nine levels of seismites from spituk leh and eight levels from khalsar sections are recorded the deformed sediments comprise of clay silts and sand and are restricted to a single stratigraphic layers bounded by undeformed beds suggesting synsedimentary deformation the various deformational structures identified are simple and complex convolutes pinch and swell bedding microfolds and microfaults flame like structures pseudonodules clay diapirs ball and pillow structures pillar structures sedimentary dykes and mud lenses the release of stress along the isz ssz and kf may have been responsible for inducing seismicity in the area during the late quaternary times which may have caused liquefaction as a direct consequence of permanent deformation of ground surface due to earthquakes of large magnitudes 5 intensity the chronological data suggests release of stresses along isz ssz and kf in the form of earthquakes between 35 000 yr bp to approximately the last glacial maxima lgm as evident form the available chronology

sedimentation model for the quaternary intramontane bhimtal naukuchiatal lake deposits nainital india abstract the bhimtal naukuchiatal lake was created due to blocking of the valley by a huge debris flow along a narrow outlet at about 40 ka bp the lake basin was filled intermittently due to fluvio lacustrine and colluvial processes that deposited a thick sequence of interbedded mud and gravel in the basin fill sequence five major lithofacies most of them divisible into subfacies have been identified and assigned to specific depositional environments the coarsening upward cu mud silt cycles represent sedimentation in a lake setting the clasts and mud supported gravels consists of fining upward fu and cu sequences respectively indicating deposition by channel processes and debris flows having basin wide extent the pedogenic mottled clayey silt unit represents an important tectonic event when the lake was temporarily drained and sediments were sub aerially exposed fluctuating arid semiarid to humid climatic conditions and repeated tectonic activity may have governed the mode of sedimentation and ultimately the basin fill history

late quaternary climatic changes in the eastern kumaun himalaya india as deduced from multi proxy studies abstract an event of neotectonic activity on an ne sw trending subsidiary fault in the zone of e w running intracrustal boundary thrust south almora thrust in the champawat district of eastern kumaun himalaya resulted in creation of a lake at ca 21 5 bp the lake drained in the late holocene leaving behind a 5 0 m thick sedimentary sequence of mostly black and carbonaceous mud with a minor magnetic reversal between 20 5 and 19 7 ka bp at the base the profile studied by using multi proxies e g carbon isotopes pollen analysis palaeo and mineral magnetism and clay minerals has recorded globally well established abrupt climatic events in the last 20 000 years such as the lgm older dryas od younger dryas yd holocene warming 8 2 ka and 4 2 ka events most events estimated assuming a constant rate of sediment accumulation for similar lithologies may be related to the rapid changes in the local climate and albedo structure the itcz may have played a key role in controlling the behavior of the southwest monsoon from the lgm

sedimentation pattern in a trans himalayan quaternary lake at lamayuru ladakh india abstract located on the indo tsangpo suture zone lamayuru lake in western ladakh was created by neotectonic instability around 35 40 ka the valley fill sequence about 110 m thick reveals an interplay of lacustrine to fluvio deltaic to colluvial processes operating in response to changing climate and tectonic conditions based on integrated approach of sedimentology and palaeontological analysis we propose a sedimentation model for lamayuru lake with reference to changing climatic conditions and neotectonics the coarsening upward succession was divided into five lithofacies associations associations a e each association comprising one or more lithofacies represents a specific depositional environment and marks an independent episode of sedimentation a dominantly muddy sequence of facies association a a product of a lacustrine environment is followed by coarsening upward cycles association b composed of silt to sand that implies laterally shifting deltas thereafter thick sand and gravel deposits constituting fining upward fu unit cycles associations c and d represent deposition in a fluvial domain the upper part of association d composed of matrix supported gravel horizons was deposited as debris flows and marks the termination of sedimentation in the valley the clastic lithofacies facies associations a to d with plant fragments and charcoal presumably indicate warm humid climatic conditions in contrast association e comprising marl lithofacies occurring at four different levels is biogenic and indicates arid to semi arid climatic phases five main types of trace fossils including rhizoliths seem to be representatives of scoyenia ichnofacies and animal burrows indicating a thin population of soft bodied annelid and arthropod communities living under low energy condition nine fossiliferous horizons have yielded characteristic ostracods charophytes and gastropods indicating shallow low energy and cold water ecological conditions coarsening up lake succession extensive synsedimentary deformation tilting of lake beds and the entrenchment of the lamayuru drainage indicate basin evolution under an effective role of neotectonics in the area

quantitative analysis of sea ice draft 1 methods for stochastic modeling this paper seeks to develop a robust set of tools for estimating the stochastic properties of sea ice drafts five parameters are estimated along with their formal uncertainties mean draft rms topographic variation characteristic length fractal dimension and normalized skewness these provide an objective basis for terrain classification a recent 10 km by 10 km upward looking submarine sonar survey serves as a test case data profiles are compared with synthetic profiles generated from the statistical parameters estimated from the data these provide a means of qualitatively assessing the success of the stochastic model at characterizing the principal morphological properties in general the comparisons are good providing confidence in the applicability and versatility of the stochastic model a few exceptions are notable but these also provide valuable insight into our understanding of the morphology of sea ice draft

spatial and temporal deformation characteristics of marine alluvial deposits due to land reclamation implications from insar observation and geotechnical estimate ground deformation of reclaimed land is a key issue for reclamation design construction and sustainable development in coastal areas as this consolidation process of the underlying compressible marine sediment sequences over very long time periods could lead to damage of both ground constructions and underground facilities in this case study we have investigated the spatial and temporal characteristics of residual reclamation settlement of chek lap kok airport hong kong one of the largest land reclamation projects worldwide a total of 25 time series envisat asar datasets acquired between december 2003 and october 2008 were used to retrieve settlement rates and deformation history at high resolution and accuracy by means of advanced synthetic aperture radar interferometry insar the insar derived results show a fairly homogenous and stable pattern in the sectors of the airport site corresponding to the two original islands of chek lap kok and lam chau in contrast a relatively high spatial settlement variability ranging from moderate 3 7 mm yr to strong 10 mm yr settlement rates was discovered within the majority of the reclaimed portion of the airport a joint analysis of insar observations and geological materials indicates that the variability of the recorded residual settlement was highly correlated with the variations of thickness and pre consolidation state of alluvial deposits below the reclamation a quantitative comparison analysis also has been carried out between time series insar observations and theoretical estimates of residual settlement modelled by geotechnical investigations the results imply that a primary consolidation process in alluvial deposits below the reclamation might be delayed with respect to the predicted results and may still have been occurring in most reclaimed areas during the investigation period 2003 2008 the time to complete it could stretch to decades depending on hydraulic conductivity and natural drainage conditions copyright 2010 john wiley sons ltd

seismically induced soft sediment deformation structures seismites around sumdo in the lower spiti valley tethys himalaya abstract soft sediment deformation structures were observed in 120 m thick fluvio lacustrine sediments exposed in the sumdo area in the lower spiti valley tethys himalaya himachal pradesh india these structures vary in their morphology and pattern and occur at eight stratigraphic levels s1 s8 spaced at irregular intervals the deformation structures include over steepened stratification diapiric flame like intrusions of clayey material or complex type recumbent folding of flame like nature pseudonodules large scale soft sediment folding faulting small scale associated with folding and sand dykes these structures are restricted to single stratigraphic layers separated by undeformed beds and can be correlated over a large distance the deformation of the soft sediments is attributed to the combined effects of fluidization liquefaction and shear stress and can be related to past seismic activity in the area recently on 19 january 1975 a major earthquake kinnaur earthquake of magnitude 6 8 caused extensive damage including ground rupturing in the sumdo kaurik area this earthquake has been related to the activation of the kaurik chango fault the deformed layers seismites reported here lie adjacent to this fault zone and can be related with episodic seismicity along this fault it is evident from this study that the kaurik chango fault has been re activated a number of times and that the area suffered at least nine major earthquakes with a magnitude of more than 6 during late pleistocene holocene time including the 1975 kinnaur earthquake

comparison of the sea ice thickness distribution in the lincoln sea and adjacent arctic ocean in 2004 and 2005 results of helicopter borne electromagnetic measurements of total ice plus snow sea ice thickness performed in may 2004 and 2005 in the lincoln sea and adjacent arctic ocean up to 868 n are presented thickness distributions south of 848 n are dominated by multi year ice with modal thicknesses of 3 9 m in 2004 and 4 2 m in 2005 mean thicknesses 4 67 and 5 18 m respectively modal and mean snow thickness on multi year ice amounted to 0 18 and 0 30 m in 2004 and 0 28 and 0 35 m in 2005 there are also considerable amounts of 0 9 2 2 m thick first year ice modal thickness mostly representing ice formed in the recurring refrozen lincoln polynya results are in good agreement with ground based electromagnetic thickness measurements and with ice types demarcated in satellite synthetic aperture radar imagery four drifting buoys deployed in 2004 between 868 n and 84 58 n show a similar pattern of a mean southward drift of the ice pack of 83 18 km between may 2004 and april 2005 towards the coast of ellesmere island and nares strait the resulting area decrease of 26 between the buoys and the coast is larger than the observed thickness increase south of 848 n this points to the importance of shear in a narrow band along the coast and of ice export through nares strait in removing ice from the study region

palaeoclimatic changes deduced from 13c 12c and c n ratios of karewa lake sediments india most long palaeoclimatic records based on isotope studies have come from deep sea cores however in order to obtain information on regional climatic variations it is essential to study continental deposits the chief limitation has been the lack of well preserved datable geological records with the exception of cave formations we report here values for the stable carbon isotope ratio 13c 12c and the elemental carbon to nitrogen c n ratio of the organic fraction of the palaeomagnetically and radiometrically dated pleistocene karewa lake sediments from kashmir india together the two ratios which are anticorrelated provide an excellent marker of the source of organic matter in the lake the karewa sediments indicate at least three major episodes of shallower than normal levels these episodes of shallow lake levels and hence a cold dry climatic regime are broadly correctable with deep sea records

a sixty thousand year paleomagnetic record from gulf of california sediments secular variation late quaternary excursions and geomagnetic implications a unique inclination record of geomagnetic secular variation for the past 60 000 years 60 ka has been obtained from continuously deposited sediments in the gulf of california recovered during deep sea drilling project dsdp leg 64 by hydraulic piston coring at site 480 the chronology of hole 480 was determined by 18o stratigraphy and varve counts indicating sedimentation rates approaching 1 m ka the paleomagnetic results of the upper 49 m show 1 the average inclination over this interval is identical to the geocentric axial dipole value at the sampling site 2 excursion directions occur between about 53 and 22 ka before present bp during this time the geomagnetic field was generally noisier than in the overlying and underlying sections with greater dispersion of the inclination 3 the laschamp excursion was apparently recorded at hole 480 between about 51 and 49 ka bp and the mono lake excursion between about 29 and 26 ka bp in addition a narrow 0 3 0 4 m zone near 23 ka bp has a very similar paleomagnetic signature as the excursion observed at summer lake oregon 1 and we suggest that the summer lake is distinct from and younger than the mono lake excursion by 3 5 ka and of considerably shorter duration lasting no more than a few hundred years 4 recurring inclination fluctuations were identified at site 480 characterized by end points with steep inclinations and shallow intermediate value s as compared with the geocentric axial dipole the inclination cycles are particularly apparent from 54 to 24 ka bp with a characteristic period of about 4 4 ka 5 the noisier inclination record between 54 and 24 ka bp might be related to the generally reduced dipole moment between about 20 and 50 ka and particularly low paleointensities for the laschamp and mono lake excursions

late quaternary valley infill and dissection in the indus river western tibetan plateau margin abstract the indus one of earth s major rivers drains large parts of the nw himalaya and the transhimalayan ranges that form part of the western tibetan plateau margin in the western himalayan syntaxis where local topographic relief exceeds 7 km the indus has incised a steep bedrock gorge at rates of several mm yr 1 upstream however the upper indus and its tributaries alternate between bedrock gorges and broad alluvial flats flanked by the ladakh and zanskar ranges we review the late quaternary valley history in this region with a focus on the confluence of the indus and zanskar rivers where vast alluvial terrace staircases and lake sediments record major episodes of aggradation and incision new absolute dating of high level fluvial terrace remnants using cosmogenic 10 be optically and infrared stimulated luminescence osl irsl indicates at least two phases of late quaternary valley infilling these phases commenced before 200 ka and 50 20 ka judging from terrace treads stranded 150 m and 30 40 m above modern river levels respectively numerous stacks of lacustrine sediments that straddle the indus river 200 km between the city of leh and the confluence with the shyok river share a distinct horizontal alignment constraints from irsl samples of lacustrine sequences from the leh spituk area reveal a protracted lake phase from 177 ka to 72 ka locally accumulating 50 m thick deposits in the absence of tectonic faulting major lithological differences and stream capture we attribute the formation of this and other large lakes in the region to natural damming by large landslides glaciers and alluvial fans the overall patchy landform age constraints from earlier studies can be reconciled by postulating a major deglacial control on sediment flux valley infilling and subsequent incision that has been modulated locally by backwater effects of natural damming while comparison with pleistocene monsoon proxies reveals no obvious correlation a late or post glacial sediment pulse seems a more likely source of this widespread sedimentation that has partly buried the dissected bedrock topography overall the long residence times of fluvial alluvial and lacustrine deposits in the region 500 ka support previous studies but remain striking given the dominantly steep slopes and deeply carved valleys that characterise this high altitude mountain desert recalculated late quaternary rates of fluvial bedrock incision in the indus and zanskar of 1 5 0 2 mm yr 1 are at odds with the longevity of juxtaposed valley fill deposits unless a lack of decisive lateral fluvial erosion helps to preserve these late pleistocene sedimentary archives we conclude that alternating 10 4 yr long phases of massive infilling and incision have dominated the late quaternary history of the indus valley below the western tibetan plateau margin

late quaternary geomorphic scenario due to changing depositional regimes in the tangtse valley trans himalaya nw india abstract records from the tangtse valley in the trans himalaya reveal depositional history since 48 ka with fluvial aggradation followed by incision lacustrine sediment fill and later incision varied sedimentary architecture with fluvial episodes intervened by lacustrine pulses flood events colluvial and glacial activity are preserved the valley is located west of the pangong tso bangong co one of the largest lakes in tibet which has served as a spillway flooding and damming the entire tangtse valley resulting in the formation of a lake today pangong tso consists of five basins separated by shallow sills and is fed by snow melt documentation based on 14 c and osl chronologies of the sediment sections throughout the valley reveals evidence of a sixth basin of pangong tso toward west occupying the present day tangtse valley between 9 6 5 1 ka this event coincides with periods of high lake levels in tibet china as well as intensified monsoon periods over the indian subcontinent a fluvial regime around 48 ka and 30 21 ka with comparatively arid conditions and dry phases interspersed by flooding is documented the valley has been incised to depths of 40 50 m in the upper part and to 130 m in the lower part the incision rate ranges from 0 3 to 1 2 mm yr 1 in the upper part and reaches as high as 10 8 mm yr 1 in the lower valley much of the incision took place between 22 and 9 6 ka although repeated sediment fill incision cycles in the valley from 30 22 ka 22 9 6 ka 9 6 5 1 ka 5 1 ka and even to present time were observed

palaeoclimatic conditions in the late pleistocene wadda lake eastern kumaun himalaya india abstract an episode of neotectonic activity on an east west trending fault in the zone of active intracrustal north almora thrust in the eastern kumaun himalaya resulted in the formation of a lake around 36 000 yr b p a 13 m continuous sequence made up largely of carbonaceous mud represents the lake that disappeared around 10 000 yr b p due to the revival of neotectonic activity on the basis of radiocarbon dating it appears that the rate of sedimentation varied from time to time during the existence of the lake palaeomagnetic studies show normal polarity except for a major deviation in the upper part of the section palynological investigations testify to the occurrence of three temperate humid and at least two well defined arid climatic phases which are correlated with previously documented late quaternary climatic changes as recorded in the himalaya as well as in tibet around 10 000 yr b p widespread deposition of a tectonically induced debris flow occurred in the lake basin at the terminal stage of the lake s life the two events ca 36 000 and 10 000 yr b p thus seem to represent two major neotectonic events in the kumaun lesser himalaya

sea ice surface roughness estimates from airborne laser scanner and laser altimeter observations in fram strait and north of svalbard we present sea ice surface roughness estimates i e the standard deviation of relative surface elevation in the arctic regions of fram strait and the nansen basin north of svalbard acquired by an airborne laser scanner and a single beam laser altimeter in 2010 we compare the scanner to the altimeter and compare the differences between the two survey regions we estimate and correct sensor roll from the scanner data using the hyperbolic response of the scanner over a flat surface measurement surveys had to be longer than 5 km north of svalbard and longer than 15 km in fram strait before the statistical distribution in surface roughness from the scanner and altimeter became similar the shape of the surface roughness probability distributions agrees with those of airborne electromagnetic induction measurements of ice thickness the ice in fram strait had a greater mean surface roughness 0 16m vs 0 09m and a wider distribution in roughness values than the ice in the nansen basin an increase in surface roughness with increasing ice thickness was observed over fast ice found in fram strait near the coast of greenland but not for the drift ice

mid to late holocene climate response from the triloknath palaeolake lahaul himalaya based on multiproxy data abstract a 2 13 m thick palaeolake sequence deposited between the right lateral moraine and the valley wall of triloknath glacier has been studied at high resolution to understand the past climatic changes in lahaul himalaya the osl and ams 14c chronology suggests that the lake building activity was initiated post cooling phase since 6484 cal ybp the combination of sedimentological geochemical and environmental magnetic parameters helped to infer five first order climatic zones the influx of magnetic minerals along with a notable increase in antiferromagnetic mineralogy appearance of hematite and higher chemical index of alteration cia values during 5925 cal ybp to 5676 cal ybp suggests warm and wet conditions owing to enhanced indian summer monsoon ism precipitation corresponding to the mid holocene warming further reduction in the magnetic mineral concentration with few peaks of antiferromagnetic mineralogy and higher cia values suggests warmer episodes within an overall cold climate and the finer ferrimagnetic grain size suggests intermittent low energy and ponding conditions during 3904 cal ybp to 2365 cal ybp this was followed by fluctuating cold arid conditions in response to reduced ism precipitation during 2365 cal ybp and 1758 cal ybp further between 1758 cal ybp to the present episodic warming pedogenic enhancement and increased monsoon precipitation have been recorded a major warm episode medieval warm period as depicted from enhanced antiferromagnetic mineralogy and higher cia values has been recorded between 742 cal yrs bp and 593 cal ybp the sudden drop in the magnetic mineral concentration as well as the cia value around 300 cal ybp 1650 ce is likely because of colder conditions prevailing during the little ice age lia the study illustrates high sensitivity of the lake sediment sequence to witness the climatic episodes experienced in the glaciated regime of the triloknath glacier

parameterization of arctic sea ice surface roughness for application in ice type classification statistics of arctic sea ice surface roughness have been investigated in order to improve classification of ice thickness regimes the data consist of surface roughness and thickness profiles acquired simultaneously by helicopter borne laser altimetry and electromagnetic induction sounding five thickness classes were identified using the modal thickness as a criterion for each class the statistical properties of the surface roughness profiles were analyzed a classification algorithm was designed which assigns profiles to the thickness classes on the basis of a set of selected statistical roughness parameters the algorithm was applied to profiles of different lengths best results were obtained for 2 km long profiles for which it was possible to discriminate well between thick first year and multi year ice and to distinguish these classes from thinner ice the classification rule was tested on data obtained under winter and summer conditions the results suggest that statistical surface roughness properties are different for thinner and thicker ice classes however individual thin ice classes cannot be discriminated on the basis of the selected roughness parameters the mass balance of sea ice is one of the key parameters in studies of the cryosphere accurate knowledge of this quantity is of fundamental importance for climate and ocean models as well as for quantifying past and future changes satellite remote sensing can be used to estimate the lateral dimension of the sea ice cover however ice thickness cannot be derived directly from satellite data so estimates of the mass balance are difficult as sea ice is found in remote regions field campaigns are difficult and costly in addition ground based thickness measurements can only be carried out on local and regional scales indirect methods to determine the mass balance of sea ice from remote sensing are therefore crucial this study presents an analysis of the surface roughness relative to level ice thickness the level ice thickness rather than the mean thickness is analyzed as it represents the prevailing thickness along a profile assuming that for sufficiently long profiles the length of the level ice sections in the profile is greater than the length of the deformed ice sections we take this value as representative of different ice types as defined by the world meteorological organiza tion s sea ice nomenclature wmo 1989 level ice thick ness is estimated from the observed modal thickness roughness in our context is determined by undulations of surface height over the entire profile comprising both smaller undulations on level ice and deformation features such as ridges and rubble the question is addressed whether different ice types can be discriminated in an analysis of the surface roughness properties goff 1995 derived a method for stochastic modelling of sea ice draft he generated synthetic draft profiles from a set of statistical parameters estimated from upward looking submarine sonar data and compared these profiles to observed data we take the positive results of his comparison as a motivation to investigate whether the roughness properties of surface profiles described by a set of statistical parameters are characteristic for different ice types the work focuses on the roughness of the top side only as this property affects measurements from air and space borne sensors such as radar and laser

microfossil evidence for changing salinity patterns in the bay of bengal over the last 20 000 years the monsson climate characterizing the northern indian ocean produces salinity gradients that are large compared with those in other open ocean areas these gradients are substantially independent of thermal and other ecologically important gradients this situation makes it possible not only to isolate the effect of salinity on sea bed distribution patterns of planktonic foraminifera but also to investigate past salinity changes along a north south transect of piston cores in the bay of bengal analysis of 152 surface sediment samples reveals that at least three factors other than salinity are important in controlling foraminiferal distribution sea bed dissolution surface productivity and surface temperature of these dissolution is the most important therefore in order to reconstruct past salinity patterns in the bay of bengal faunal indices need to be developed that isolate the effect of salinity we have developed two independent approaches the first uses ternary diagrams of the three dominant dissolution resistant species globoquadrina dutertrei globorotalia menardii pulleniatina obliquiloculata high values of g dutertrei are associated with low surface salinities the second approach uses dissolution buffered salinity transfer functions based on the total foraminiferal fauna in the 152 surface samples from the northern indian ocean applied to downcore samples these methods show the same basic historical pattern of salinity variation which is in turn consistent with independent inferences based on preliminary oxygen isotope data duplessy 1980 historical changes in the bay of bengal salinity are reconstructed along a north south transect of seven cores at 90 e the stratigraphy of the transect is controlled by oxygen isotope profiles that are similar to the generalized patterns observed in other areas over the past 20 000 yr salinity gradients are reconstructed for three time intervals 1 the last glacial maximum lgm 2 the mid termination mt and 3 the holocene during the lgm interval salinity was highger in the bay of bengal particularly in the north thus reducing the north south salinity gradient during the mt the middle of the transition from glacial to interglacial global climatic regimes northern bay of bengal surface salinity was considerably reduced while salinity to the south was generally similar to today thus the salinity gradient between 10 n and 15 n was considerably steeper than today in contrast the holocene gradient was approximately the same as the modern gradient with absolute values along the transect being slightly but uniformly higher these changes in the pattern of salinity are explained in terms of changes in the local patterns of precipitation and river run off during the lgm the salinity pattern probably results from decreased precipitation and decreased run off by the ganges brahmaputra river system during the mt decreased salinity in the northern bay of bengal is caused by increased precipitation and run off rather than by the influx of glacial meltwater the steeper mt salinity gradient in the central bay of bengal suggests increased eastward advection of equatorial surface waters by a southwest monsoon current somewhat more vigorous than today these patterns can be correlated with faunal evidence from the western arabian sea that suggest decreased upwelling during the lgm and increased upwelling during the mt this coupling of events may be associated with changes in the pattern or intensity of circulation during the southwest monsoon decreased intensity at the lgm 18 000 b p and increased intensity at the mt 10 500 to 12 500 b p

measurements of soil compaction rate by using jers 1 sar and a prediction model the soil compaction rate in a reclaimed land has been estimated by using the japanese earth resources satellite 1 jers 1 synthetic aperture radar sar two pass differential interferometry dinsar and magnetic probe extensometer an accuracy of spl plusmn 1 mm from 42 ground stations twelve jers 1 sar interferometric pairs were acquired in the study area we applied a soil compaction prediction model based on a hyperbolic method using the ground truth data and the dinsar measurements the hyperbolic model fitted well to the ground measurements with an rms error of 1 65 cm the rms error of the model driven by dinsar measurements was 2 24 cm the two model results agreed well showing a difference of 8 1 12 9 cm in permanent settlement that is defined as the amount of vertical subsidence as time goes to infinity a two dimensional 2 d subsidence map was constructed from five qualified pairs the correlation coefficient r between the radar measurements and the ground truth data was 0 87 with an rms error of 1 44 cm the results demonstrate that the l band dinsar combined with a prediction model is useful for geotechnical applications

quaternary geology tectonics and distribution of palaeo and present fluvio glacio lacustrine deposits in ladakh nw indian himalaya a study based on field observations abstract the ladakh region of the northwestern indian himalaya is rich in quaternary deposits but it has not received much attention previous quaternary research in the region has focused on the glacial sequences and only some scattered data of the lacustrine deposits are available this article addresses the reconstruction of the palaeo lacustrine deposits and the present day lakes and their distribution in the ladakh region the region was under the influence of tectonic activity and cold climate during the late quaternary times tectonic activity at 50 000 years bp 35 000 years bp and 25 000 years bp has been recorded we report the presence of three major lakes in the region in the late quaternary these formed due to the damming of the indus river and its tributaries by debris avalanches initiated mainly by tectonic activity along the indus suture shyok suture and the karakoram fault these are the spituk leh palaeolake formed 50 000 years bp the lamayuru palaeolake dated to 35 000 years bp in the indus valley and the khalsar palaeolake 60 km in length in the shyok valley vast exposures of the palaeolake deposits ranging from 25 to 150 m in thickness are reported spituk section 25 m lamayuru section 110 m and khalsar 150 m and hundri 100 m and which have a wide lateral extent a glacial lake basin at bhaktpur city north of baralacha la is now completely filled the tsokar lake has been subdivided into smaller units now and the water level is lowering other lakes in the region e g pangong tso tso morari the twin kyun tso lakes are confined to the western side of the study area limited chemical weathering rapid erosion and cold climatic conditions in late quaternary times are suggested by the stable illite values in the lamayuru section four levels of palaeoseismic structures convolute structures sand dykes intraformational folds micro faulting are present in the khalsar section and at three levels in the tirit section at shyok nubra confluence palaeoseismic activity was also prevalent after 25 000 years bp as is evident from the three levels of palaeoseismic structures in the younger sediments