sinking cities in indonesia alos palsar detects rapid subsidence due to groundwater and gas extraction abstract we use interferometric synthetic aperture radar insar time series analysis of alos l band sar data to resolve land subsidence in western indonesia with high spatial and temporal resolution the data reveal significant subsidence in nine areas including six major cities at rates up to 22 cm year land subsidence is detected near lhokseumawe in medan jakarta bandung blanakan pekalongan bungbulang semarang and in the sidoarjo regency the fastest subsidence occurs in highly populated coastal areas particularly vulnerable to flooding we correlate the observed subsidence with surface geology and land use despite the fact that subsidence is taking place in compressible deposits there is no clear correlation between subsidence and surface geology in urban areas we find a correlation between rapid patchy subsidence and industrial land use and elsewhere with agricultural land use this suggests that the subsidence is primarily caused by ground water extraction for industrial and agricultural use respectively we also observe subsidence associated with exploitation of gas fields near lhokseumawe and in the sidoarjo regency a continuation of these high rates of subsidence is likely to put much of the densely populated coastal areas below relative sea level within a few decades

formation of diamond with mineral inclusions of mixed eclogite and peridotite paragenesis two unusual diamonds were studied from kimberlites from china which contain both ultramafic and eclogitic mineral inclusions in the same diamond hosts diamond l32 contains seven fe rich garnets four omphacites and one olivine inclusion four olivine one sanidine and one coesite were recovered from diamond s32 both garnet and omphacite inclusions have similar compositions as those from other localities of the world and show basaltic bulk composition all the garnet and omphacite inclusions in diamond l32 have positive eu anomalies eu eu 1 64 1 79 these observations support the proposal that mantle eclogite is the metamorphic product of subducted ancient oceanic crust the mg mg fe ratio of the olivine inclusions from the two diamonds 91 92 are evidently lower than the normal olivine inclusions in diamonds from the same kimberlite pipe 92 95 the following model is proposed for the formation of diamonds with mixed mineral inclusions ascending diamond bearing eclogite recycled oceanic crust entrained in mantle plumes may experience extensive partial melting whereas the ambient peridotite matrix remains subsolidus in the diamond stable field this provides a mechanism for the transport of diamond from its original eclogitic host to an ultramafic one subsequent re growth of diamond in the new environment makes it possible to capture mineral inclusions of different lithological suites partial melts of basaltic sources may interact with the surrounding peridotite resulting in the relatively lower mg mg fe ratios of the coexisting olivine inclusions from the studied diamonds diamonds with mixed mineral inclusions demonstrate that plume activity also occurred in the archean cratons

processes of selective grain transport and the formation of placers on beaches placers are found on many beaches of the oregon coast in the beach that is the focus of this study the principal placer minerals are ilmenite 22 0 epidote 20 0 garnet 18 7 augite 15 5 hypersthene 8 1 hornblende 5 8 and zircon 2 0 the ilmenite fraction actually being partly chromite a series of beach face sand samples was obtained along a profile when sand was being eroded from the upper beach and transported to offshore bars since the processes of grain selective sorting leading to placer formation were probably most active at such a time the landward most sample contained 96 heavy minerals being part of the placer this concentration systematically decreased offshore to a 6 heavy mineral content in the seaward most sample 54 m offshore determinations of individual heavy mineral concentrations revealed that although they all tended to become concentrated within the placer with light quartz and feldspar dominating the offshore transport the sorting processes were m

the black sand placer deposits of kerala beach southwest india abstract heavy mineral concentrates known as black sands occur in layers and patches along the kerala beaches situated on the southwest coast of india detailed microscopic studies of 28 beach samples and 32 river bed samples from 16 west flowing rivers of kerala were examined the heavy mineral suite consists of opaques hornblende tremolite actinolite hypersthene clinopyroxene zircon monazite garnet sillimanite epidote staurolite apatite etc distribution maps of these minerals on the beaches and in river sediments have been prepared opaques as high as 96 were noted in some samples on the beach the minerals are derived mainly from the charnockites khondalites granite gneisses pegmatites or retrograde charnockites from the drainage basins of the different rivers a combination of two or more characteristic minerals was also identified for the major rivers of kerala five heavy mineral provinces on the beach were recognised from north to south they are 1 mixed mineral province with opaques zircon hornblende garnet sillimanite epidote 2 garnet hypersthene province 3 opaque zircon province 4 hornblende hypersthene province and 5 opaque zircon monazite province vigorous wave activity during the southwest monsoon the longshore current and onshore offshore movements played an important role in sorting the heavy mineral placer sands a three stage depositional model of the heavy mineral placer sands corresponding to the initial transgressive and regressive stages influenced by wave and current activity is suggested

a numerical study of the interaction between the mantle wedge subducting slab and overriding plate abstract we have formulated a numerical model with strongly temperature dependent viscosity to calculate thermal structure and flow field in subduction zones one important particularity of the model is that the overriding plate is not fixed over its whole thickness in order to allow material exchange between the wedge and the upper lithosphere numerical problems due to very high viscosity contrasts are avoided by coupling a finite difference method and a finite element method for solving the energy conservation equation and the stockes equation respectively in this model a temperature decrease from 1400 to 1300 c increases the viscosity by an order of magnitude we study the temperature structure and the velocity field of the subducting slab and mantle wedge surface heat flow velocity anomalies and geometry of the partial melting zone are also calculated to study the effect that boundary conditions play on the interaction between the mantle wedge overriding plate and subducting plate we examine models with both fixed and free slip conditions applied to the overriding plate when the overriding plate is allowed to move laterally free slip the subducting slab is thick and both the temperature field and the convective motions in the mantle wedge are similar to those observed when using constant viscosity numerical models or analytical corner flow models if the surface of the overriding plate is fixed the subducting slab is thin and the mantle wedge impinges upon the overriding plate forming a high temperature nose between the overriding plate and subducting lithosphere furthermore viscous decoupling occurs implicitly at shallow depth between the slab and the wedge because hot material from the wedge is entrained close to the trench in that case the subducting slab tectonically erodes the lower lithosphere of the overriding plate leading to high temperatures low seismic velocities high attenuation and high heat flow beneath volcanic arc in agreement with geophysical observations

the eclogite garnetite transformation at high pressure and some geophysical implications mineral assemblages displayed by morb and alkali poor olivine tholeiites have been investigated over the pressure interval 4 6 18 gpa at 1200 c both compositions crystallize to form normal eclogites between 4 6 and 10 gpa and there is little change in the relative proportions of garnet and pyroxene over this range however the proportion of garnet increases rapidly above 10 gpa as pyroxene dissolves in the garnet structure and pyroxene free garnetites stishovite are produced by 14 15 gpa dependent upon composition the garnetite facies for both compositions possess zero pressure densities of 3 75 g cm3 implying that subducted oceanic crust remains appreciably denser than surrounding mantle to depths exceeding 600 km it is demonstrated that the seismic velocity distributions in the mantle between 400 and 650 km are inconsistent with anderson s hypothesis that this region is of eclogitic composition

survival of pyropic garnet in subducting plates abstract an experimental study has been conducted to clarify the conditions and kinetic aspects of the pyroxene garnet transformation by using synthetic polycrystals two pyroxenes garnet in the cao mgo al 2 o 3 sio 2 system the run products recovered from the in situ x ray diffraction experiments in a double stage multi anvil system at 15 5 20 4 gpa and 800 1600 c were carefully analyzed by scanning electron microscopy our results show that the pyroxene garnet transformation proceeds by overgrowth of garnet absorbing the surrounding pyroxene components above 1550 c at 18 4 gpa and 1320 c pyroxenes enstatite diopside directly decomposed to the assemblages wadsleyite stishovite ca perovskite without dissolving in garnet the pyroxene garnet transformation requires much higher temperatures than those needed for transformation of olivine to wadsleyite 1000 c and of pyroxenes to their high pressure phases 1300 c in laboratory time 10 3 s and grain 10 5 m scales therefore the pyroxene garnet transformation is likely to be kinetically inhibited at low temperatures in the subducting plate and the pyropic garnet could survive in the transition zone instead of equilibrium majoritic garnet

a comparison of global rare earth element ree resources and their mineralogy with ree prospects in sri lanka abstract rare earth elements rees a group of 17 elements comprises 15 lanthanides scandium and yttrium are largely attracting the world s attention due to their importance in a wide variety of advanced technological applications global rees production is mainly sourced from resources such as carbonatites alkaline igneous rocks placers laterites and ion adsorption clays recently ree demand has been escalating especially due to the ree applications in renewable energy and defense sectors expecting a worldwide shortage of ree supply in the future therefore rees have been widely accepted as strategic elements in the world which compels to prospect for new and alternative ree resources in this context sri lanka has a favorable geological setting which implies the presence of ree mineralization previous geochemical studies in sri lanka have reported significant concentrations of rees in different geological formations and mineral resources accordingly pulmoddai and other beach placer deposits eppawala carbonatite alluvial placer deposits and pegmatites have been identified as potential ree resources in sri lanka monazite apatite allanite and zircon are the primary rare earth re minerals found in the preceding resources the pulmoddai mineral sand deposit is considered as the most potential ree resource in the island which is enriched in monazite containing more than 61 of light rare earth elements lrees similarly eppawala carbonatite contains high concentrations of lrees however despite their significant ree enrichments to date no attempt has been made to recover these ree prospects which essentially conceals their potential of catering for both local and global ree supply chains

processes controlling arsenic enrichment along the eastern arabian sea surficial sediments the processes enriching redox sensitive arsenic as was investigated in 111 surficial sediments 27 3679 m water depth overlain by varying levels of dissolved oxygen along the eastern arabian sea under oxygenated conditions diagenetic enrichment of as was noticed at deeper water depths 1200 m while lattice held as dominant at few station from shallow depths 150 m in sediments impinged by oxygen minimum zone omz 150 1200 m as is released from organic matter during sub oxic diagenesis as seems to precipitate as as iron sulfide mineral under intense omz based on a positive correlation between as and s and cd in northeastern part of the study area while as may diffuse to water column under less intense omz evidenced by lack of correlation between as and s and cd in southeastern part several processes can enrich as a careful approach is recommended for its usage in understanding anthropogenic sources transport and paleodepositional environment along eastern arabian sea

the crystal structure of diopside at pressure to 10 gpa the crystal structure of diopside has been determined at various pressures to 10 16 gpa the results to 5 gpa are consistent with levien and prewitt 1981 the crystal structures have been analyzed using the geometric pyroxene model of thompson and downs 2004 the anion packing algorithm of thompson and downs 2001 and a new algorithm that quantifies the distortion of observed pyroxenes from their geometric model equivalents diopside is shown to compress via three main mechanisms isotropic scaling kinking of the tetrahedral chains and collapse of the m1 chain toward its axis the kinking of the chains accounts for most of the anisotropy of compression observed in the a c plane and the collapse of the m1 chain explains the anisotropy seen in the b c plane model behavior is shown to reproduce many of the observations of previous workers anion anion interactions are shown to be important in the distortion of observed diopside from its geometric model equivalent

distribution geometry and origin of heavy mineral placer deposits on oregon beaches abstract beach segments 0 5 3 km in length enriched in heavy minerals 20 100 by weight abundance are located south of six prominent headlands that interrupt the 175 km coastline between cape lookout and cape perpetua oregon beach face retreat in the winter of 1982 83 exposed underlying placers containing the economic minerals garnet zircon ilmenite and chromite in each case the highest concentration of placer minerals occurs in an area of maximum shoreline curvature at a distance south of the north bounding headland that is proportional to seaward extent of the headland cross sections and magnetic surveys of one 8 km coastal section otter rock to yaquina head define a small placer body heavy minerals 50 some 0 75 km in length and 80 103 m3 in volume that comprises 10 of the total beach sand between the bounding headlands mineral grain size analyses of winter beach samples along this coastal section confirm earlier models of mineral segregation by entrainment processes the light minerals are more susceptible to fluid shear stress than the heavy minerals maximum segregation and heavy mineral enrichment occur in the backshore and at shoreline inflection points where decreasing flow velocities produce gradients of fl id shear stress allowing light minerals to be winnowed from more stable heavy minerals development of placer deposits is controlled by shoreline configuration as the first order factor and seasonal variations of wave climate and longshore currents as second order factors that delineate shape and concentration of heavy minerals in placer bodies

coastal zone management programme in kerala india the physiographic setting of kerala state india is unique a narrow strip of the state contains a chain of lagoons and estuaries with a very high population density the strip is subjected to severe coastal erosion during the monsoon season a number of other problems are also associated with the coastal zone of kerala such as irregular dredging of black sands from the beaches coastal flooding hazards due to developmental activities etc a coastal zone management programme was developed and administered by the centre for earth science studies trivandrum to provide efficient coastal management and solve some of these problems various programmes included under the coastal zone management are the following 1 sedimentological bathymetric and geochemical studies of lagoons and estuaries 2 monitoring of planimetric changes of beaches by profiling beaches during different seasons all along the coast 3 studies of the nature distribution and provenance of black sand deposits from beaches 4 studies of the peculiar occurrence of patchy calm turbid areas of water in the offshore containing high suspended sediment concentrate known as mud banks 5 wave studies involving continuous monitoring of wave data all along the coast in order to understand wave climate and erosion 6 sediment movement studies using fluorescent tracer to aid in the development of ports and harbors 7 studies on various aspects of offshore the outlines of the various programmes discussed in this article will help other states and countries to develop a coastal zone management programme according to the needs of the state or country and the nature of the problem occurring in the coastal zone

influence of provenance weathering and sedimentary processes on the elemental ratios of the fine grained fraction of the bedload sediments from the vembanad lake and the adjoining continental shelf southwest coast of india abstract geochemical studies comprising twelve major elements and twenty four trace elements including the rare earth elements ree have been carried out on the concentrations normalized to the average upper continental crust ucc show that the sediments studied are depleted in rb k ba ta hf na and ca and enriched in cs u th rees sc fe co and cr ucc normalized patterns are strikingly similar for all the three sediment types probably because of efficient mixing of sedimentary material during weathering transport and deposition the depletion of na k ca and ba in sediments relative to ucc could be attributed to their mobility during weathering the depletion of ta and hf and enrichment of th ree and sc are probably related to provenance characteristics and enrichment of u is attributed to oxidation reduction processes shale normalized ree values reveal steep hree patterns tbsample tbshale ybsample ybshale lasample lashale smsample smshale and flat lree patterns the shale normalized patterns for all the three types of sediments are remarkably similar with variations in the magnitude of lree enrichment lan ybn varies between 1 72 to 2 57 times that of paas lree enrichment and steep hree patterns are attributed to felsic source rock characteristics other geochemical characteristics such as high la th and low la sc and th sc ratios compared to ucc also support a felsic provenance eu eu values for all the three types are little more than 1 which is also a characteristic feature of archean crust furthermore data plotted on discrimination diagrams of la th vs hf and la th sc cluster closer to granite and away from basalt and komatiite and are consistent with source rock geology geochemical data have also helped in ascertaining the weathering trends the chemical index of alteration cia has been used to quantify the degree of weathering cia values range between 81 and 94 on a scale of 40 100 indicating a high degree of alteration fluvial sediments seem to be more altered on an a cn k diagram the data fall closer to the compositional fields of highly weathered minerals kaolinite gibbsite and chlorite a high degree of weathering is also indicated by other plots such as k2o fe2o3 al2o3 and log k vs log rb the geochemical data are consistent with the studies on clay mineralogy higher kaolinite carried out by other authors on the sediments of the same area secondary processes seem to affect other geochemical discriminants such as co cr ni and u as revealed by plots of 1 la sc vs co th and 2 th hf co and co th cr th ratios and makes them unsuitable for determining provenance and tectonic setting

sound velocities of fe3al2si3o12 almandine up to 19 gpa and 1700 k abstract elastic wave velocities of synthetic fe 3 al 2 si 3 o 12 almandine have been determined at simultaneous high pressure and temperature up to 19 gpa and 1700 k by the ultrasonic technique in conjunction with in situ synchrotron x ray diffraction in a multi anvil apparatus velocities of almandine are found substantially lower than those of other major end member garnets such as pyrope grossular and mgsio 3 majorite while their pressure and temperature derivatives are comparable to those of the latter garnets the observed density and compressional v p and shear v s velocities were combined and fitted to functions of the eulerian strain eos yielding a adiabatic bulk modulus k s 0 174 2 12 gpa and a shear modulus g 0 94 9 7 gpa and their pressure and temperature derivatives k s p 4 61 14 g p 1 06 6 k s t 2 67 7 10 2 gpa k 1 and g t 1 31 8 10 2 gpa k 1 the pressure derivative of the bulk modulus of almandine is similar to those of other garnet end members which is in contrast to the substantially higher value k s p 6 2 5 reported for pure almandine in an earlier study based on experiments up to 3 gpa the present new results combined with those of pyrope grossular and mgsio 3 majorite are successfully used to reproduce the sound velocities of majoritic garnet in the pyrolite composition

thermodynamic and elastic properties of pyrope at high pressure and high temperature by first principles calculations pyrope is an mg end member garnet which constitutes up to 15 of the upper mantle thermodynamic and thermoelastic properties of garnet at high pressure and high temperature are important for understanding the composition and structure of the earth here we report the first principles calculations of vibrational properties thermodynamic properties and elasticity of pyrope over a wide pressure and temperature range the calculated results exhibit good consistency with the available experimental results and provide values up to the pressure and temperature range that are challenging for experiments to achieve and measure pyrope is almost isotropic at high pressure the elastic moduli especially the shear modulus of pyrope exhibit nonlinear pressure and temperature dependences density and seismic velocities of pyrope along with piclogite pyrolite and eclogite are compared with seismic models along the normal upper mantle and the cold subducting lithospheric plate geotherms pyrope has the highest density and seismic velocities among the major minerals of the upper mantle along these geotherms eclogite with 30 pyrope and 70 clinopyroxene is denser than the surrounding mantle even along the normal upper mantle geotherm and becomes still denser along the cold slab geotherm seismic velocities of eclogite with 30 pyrope along the normal upper mantle geotherm are slower than the surrounding mantle but along the cold slab geotherm are faster than the surrounding mantle

thermoelastic properties of eclogitic garnets and omphacites implications for deep subduction of oceanic crust and density anomalies in the upper mantle

cretaceous mantle of the congo craton evidence from mineral and fluid inclusions in kasai alluvial diamonds abstract alluvial diamonds from the kasai river democratic republic of the congo drc are sourced from cretaceous kimberlites of the lucapa graben in angola analysis of 40 inclusion bearing diamonds provides new insights into the characteristics and evolution of ancient lithospheric mantle of the congo craton silicate inclusions permitted us to classify diamonds as peridotitic containing fo 91 95 and en 92 94 23 diamonds 70 of the suite and eclogitic containing cr poor pyrope and omphacite with 11 27 jadeite 6 diamonds 18 of the suite fluid inclusion compositions of fibrous diamonds are moderately to highly silicic matching compositions of diamond forming fluids from other drc diamonds regional homogeneity of congo fibrous diamond fluid inclusion compositions suggests spatially extensive homogenization of cretaceous diamond forming fluids within the congo lithospheric mantle in situ cathodoluminescence secondary ion mass spectrometry and fourier transform infrared spectroscopy reveal large heterogeneities in n n aggregation into b centers n b and 13 c indicating that diamonds grew episodically from fluids of distinct sources peridotitic diamonds contain up to 2962 ppm n show 0 88 n b and have 13 c isotopic compositions from 12 5 to 1 9 with a mode near mantle like values eclogitic diamonds contain 14 1432 ppm n n b spanning 29 68 and wider and lighter 13 c isotopic compositions of 17 8 to 3 4 fibrous diamonds on average contain more n up to 2976 ppm and are restricted in 13 c from 4 1 to 9 4 clinopyroxene garnet thermobarometry suggests diamond formation at 1350 1375 c at 5 8 to 6 3 gpa whereas n aggregation thermometry yields diamond residence temperatures between 1000 and 1280 c if the assumed mantle residence time is 0 9 3 3 ga integrated geothermobaromtery indicates heat fluxes of 41 44 mw m 2 during diamond formation and a lithosphere asthenosphere boundary lab at 190 210 km the hotter than average cratonic mantle may be attributable to contemporaneous rifting of the southern atlantic multiple post archean reactivations of the craton and or proximal cretaceous plumes

elasticity of diopside to 8 gpa and 1073 k and implications for the upper mantle abstract simultaneous measurements of elastic wave velocities and density have been conducted on diopside by a combined ultrasonic interferometry and x ray diffraction methods at pressure and temperature conditions relevant to the earth s upper mantle the current study not only yielded the first direct measurement of the shear modulus at high pressures but also enabled a simultaneous determination of the bulk and shear properties and their pressure and temperature derivatives from the measured density and velocities finite strain analysis of the experimental data results in ks0 116 4 7 gpa k s 0 4 9 1 ks t p 0 012 1 gpa gpa g 0 1 6 1 and g t p 0 011 1 gpa k with these results and the same finite strain equations the p and s wave velocities of diopsidic mantle clinopyroxene were calculated along a 1600 k adiabatic geotherm in comparison with other mantle minerals the seismic velocities of diopsidic clinopyroxene at upper mantle depths are 1 3 higher than those of orthopyroxene 1 2 and 6 8 lower than those of olivine and majoritic garnet respectively

density of morb eclogite in the upper mantle in order to study the role of eclogite subducted oceanic crust in geodynamics we carried out high pressure experiments on natural mid oceanic ridge basalt morb using a multi anvil apparatus we determined phase relations of morb as a function of pressure and temperature in the temperature range of 1200 1700 c and pressures from 5 to 14 gpa the present results differ from a previous high pressure study of morb earth planet sci lett 77 1986 245 conducted at 1200 c as follows 1 coesite coe or stishovite st appears throughout the studied pressure range and 2 the clinopyroxene garnet cpx gar ratio is smaller particularly in the low pressure range 12 gpa our results show that the calculated bulk density of subducted oceanic crust increases discontinuously at around 9 gpa due to the coesite stishovite phase transition the density is considerably higher than estimates based on the previous experiments at pressures less than 12 gpa thus the role of eclogite in driving subduction should be more important than previously thought on the other hand the density difference between peridotite and eclogite in ascending mantle plumes becomes smaller as temperature increases a result of the increase in clinopyroxene garnet sio2 ratio in eclogite with increasing temperature as eclogite is still denser than peridotite even under subsolidus conditions recycled oceanic crust entrained in ascending plumes must be sustained by the upward flow of ambient peridotite in mantle plumes

evolution of late holocene coastal dunes in the cauvery delta region of tamil nadu india widespread occurrences of coastal dunes are observed in the cauvery delta region of tamil nadu in vedaranniyam in the south east coast of india these dunes were studied to establish the chronology of their formation and to understand their evolution using optically stimulated luminescence osl dating in combination with sedimentological studies quartz grain surface morphology using scanning electron microscope grain size and heavy mineral analysis the study shows that on the south east coast of india widespread periodic dune formation reactivation has taken place during the late holocene to very recent times due to a variety of reasons such as climatic variation and land use changes the sand mobility index shows that the dunes in the area have been largely active during the past century in the southern part in nagapattinam region and many of the crests were active in the northern cauvery delta in cuddalore region the angularity and fresh appearance of sand in the inland dunes suggest a short distance of sand transport and a source proximal sand deposition was proposed for the dune formation the study demonstrates the sensitivity of sand dunes on the south east coast of india to varying climatic conditions and changes in regional land use

topography correlated atmospheric delay correction in radar interferometry using wavelet transforms 1 atmospheric delay is one of the major sources of error in repeat pass interferometry we propose a new approach for correcting the topography correlated components of this artifact to this aim we use multiresolution wavelet analysis to identify the components of the unwrapped interferogram that correlate with topography by using a forward wavelet transform we break down the digital elevation model and the unwrapped interferogram into their building blocks based on their frequency properties we apply a cross correlation analysis to identify correlated coefficients that represent the effect of the atmospheric delay thus the correction to the unwrapped interferogram is obtained by down weighting the correlated coefficients during inverse wavelet transform we test this approach on real and synthetic data sets that are generated over the san francisco bay area we find that even in the presence of tectonic signals this method is able to reduce the correlated component of the atmospheric delay by up to 75 and improves the signal in areas of high relief the remaining part is most likely due to 3d heterogeneities of the atmosphere and can be reduced by integrating temporal information or using complementary observations or models of atmospheric delay

single crystal elasticity of diopside to 14 gpa by brillouin scattering the single crystal elastic moduli cij of diopside have been measured up to 14 gpa using brillouin spectroscopy from which the aggregate compressional and shear velocities adiabatic bulk modulus shear modulus and their pressure derivatives were obtained a least squares fit of the velocity pressure data to third order finite strain equation yields k

influence of nearshore sediment dynamics on the distribution of heavy mineral placer deposits in sri lanka beach sediments in sri lanka contain industrial grade heavy mineral occurrences samples of both offshore and onshore sediments were collected to examine the provenance mineralogy and geochemical compositions of the heavy mineral occurrences coastal morphodynamic changes along the coastline of sri lanka were analyzed using the time series satellite images these coastal morphodynamic changes were used to identify the prominent directions of monsoon influenced longshore currents coastal sediment accretion and depositional trends and their relationships to the provenance of the heavy minerals results show the concentrations of detrital ilmenite zircon garnet monazite and rutile vary in the onshore and offshore sediments the heavy mineral potential of the northeastern coast is high average contents of about 45 50 in the verugal deposit 70 85 in the pulmoddai deposit and 3 5 5 0 in offshore samples stretching from nilaveli to kokkilai compared to sediments in southwest average content about 10 in onshore sediments and 2 in offshore sediments from the mouth of the gin river therefore no economic grade heavy mineral placers were identified in the offshore environments the high concentrations of heavy minerals in beach sediments and low concentrations in offshore sediments suggest operation of a panning system in the surf zone to form enriched placer deposits major and trace element compositions of beach sediments show marked enrichments of tio2 fe2o3 la ce zr cr nb th and v compared to average upper continental crust ucc values analysis of prominent coastal longshore transport patterns identifies bidirectional sediment transport in the northeast coast of sri lanka in the southwestern coast two transport directions occur with anti clockwise transport from galle to hambantota and clockwise transport from hikkaduwa to wadduwa the heavy minerals in the placers were mainly derived from precambrian metamorphic rocks and transported to the coast through the river systems of sri lanka

recent subsidence of the venice lagoon from continuous gps and interferometric synthetic aperture radar 1 coastal regions are increasingly affected by larger storms and rising sea level predicted by global warming models aggravating the situation in the city of venice where tidal induced seasonal flooding coupled with natural and anthropogenic subsidence have been perennial problems in light of accelerated efforts to protect venice from the rise in sea level we assess land subsidence in the venice lagoon over the last decade through a combined analysis of gps position time series from 2001 55 to 2011 00 for four stations installed by the magistrato alle acque di venezia and thousands of observations of insar permanent scatterers using radarsat 1 images from 2003 3 to 2007 85 we determine that the northern lagoon subsides at a rate of 2 3 mm yr whereas the southern lagoon subsides at 3 4 mm yr the city of venice continues to subside at a rate of 1 2 mm yr in contrast to geodetic studies in the last decade of the 20th century suggesting that subsidence has been stabilized the gps results indicate a general eastward tilt in subsidence and that the natural subsidence rate related to the retreat of the adriatic plate subducting beneath the apennines is at least 0 4 0 6 mm yr our combined gps and insar analysis demonstrates high spatial resolution in the vertical direction with a precision of 0 1 0 2 mm yr with respect to a global reference frame continued efforts to secure the city of venice from flooding must also take into account the significant local and regional subsidence rates as well as the expected rise in sea level

micromorphology of some placer minerals from kerala beach india abstract scanning electron microscopic studies of placer minerals such as ilmenite rutile sillimanite zircon monazite and garnet from beach sediments of kerala indicate a number of microfeatures these features are mainly produced by mechanical impact or solution activity of chemicals an attempt has been made to identify the common grain micro textures of the placer minerals and the processes responsible for their formation impact features result in blocks fracture plates steps pits and v shaped marks solution activity results in irregular marks etch v s oriented and unoriented etch pits grooves etc the environmental significance of these features is discussed

sources of stream sediments in the granulite terrain of the walawe ganga basin sri lanka indicated by rare earth element geochemistry abstract thirty eight samples of stream sediments draining high grade metamorphic rocks in the walawe ganga river basin sri lanka were analysed for their ree contents together with samples of metamorphic suites from the source region the metamorphic rocks are enriched in light ree lree compared to heavy ree hree and are characterised by high la lu ratios and negative eu anomalies the chondrite normalised patterns for these granulite grade rocks are similar to that of the average post archaean upper crust but they are slightly enriched with la and ce the ree contents of the n sm n and lower la n lu n ratios relative to other fractions the lower la n lu n ratio is related to the depletion of heavy minerals in the

adiabatic temperature profile in the mantle abstract the temperature at the 410 km discontinuity is re evaluated by comparing the depth of the discontinuity with the olivine wadsleyite transition pressure obtained using in situ x ray diffraction experiments by katsura et al 2004a and equation of state eos of mgo by tange et al 2009 tange scale and matsui et al 2000 the newly estimated temperature is 1830 48 k 70 k higher than that by our previous estimation the eoses of the major mantle minerals olivine wadsleyite ringwoodite and perovskite are also recalculated using the tange scale the adiabatic temperature gradient is calculated using the thermal expansion coefficient obtained from these eoses the adiabatic temperature gradient gradually decreases with increasing depth without a phase transition and abruptly increases in association with phase transitions the adiabatic temperature gradients are found to be 04 0 5 and 0 3 k km in the upper and lower parts of the mantle respectively the temperatures at a depth of 200 km the bottom of the mantle transition zone the top of the lower mantle and a depth of 2700 km are found to be 1720 40 2010 40 1980 40 and 2730 50 k the mantle potential temperature is found to be 1610 35 k

elasticity of pyrope and majorite pyrope solid solutions to high temperatures abstract majorite garnet solid solutions are major mineral phases in the earth s upper mantle and transition zone here we present the first brillouin scattering measurements of the elasticity of majorite mj mg 4 si 4 o 12 pyrope py mg 3 al 2 si 3 o 12 solid solutions mj 50 py 50 and mj 80 py 20 and single crystal elasticity of pure synthetic pyrope at temperatures up to 800 c the temperature derivatives of the adiabatic bulk k s and shear moduli for all compositions along the mj py join are the same within the experimental uncertainties k s t 14 0 14 5 20 mpa k t 8 3 9 2 10 mpa k the temperature dependence of the acoustic velocities for mj py solid solutions is about half that of other major transition zone minerals this implies that temperature variations in the transition zone inferred from lateral velocity heterogeneity can be significantly underestimated if the properties of majoritic garnet are not taken into account

diamond garnet geobarometry the role of garnet compressibility and expansivity abstract we report p v and t v equations of state eos for synthetic single crystal pyrope py mg3al2si3o12 and the p v eos for synthetic single crystals of almandine alm fe3al2si3o12 as well as an intermediate composition py60alm40 as measured by in situ high pressure and high temperature x ray diffraction experiments the unit cell volumes of the three samples were measured at room temperature and different pressures and up to about 8 gpa in a diamond anvil cell the high temperature experiment was carried out using a micro furnace the pressure volume data were fitted to a third order birch murnaghan eos giving the following coefficients v0 1506 15 16 a3 kt0 163 7 1 7 gpa and k 6 4 4 for pyrope v0 1533 52 10 a3 kt0 172 6 1 5 gpa and k 5 8 5 for almandine and v0 1516 32 13 a3 kt0 167 2 1 7 gpa and k 5 6 5 for the intermediate py60alm40 composition the unit cell volume along the pyrope almandine join changes linearly within the error of measurement indicating ideality in the volume of mixing behaviour for the solid solution the first pressure derivative k for all three garnets is similar within experimental uncertainty with an average value of k 6 0 4 the thermal expansion parameters for end member pyrope as described using to the kroll type eos with the einstein temperature e fixed to 320 k are 303 k 1 bar 2 543 5 10 5 k 1 and v0 1504 64 4 a3 the determined thermoelastic parameters were combined in a thermal pressure type eos thermal p type eos to calculate the entrapment pressures pe for natural garnet inclusions in diamonds at mantle temperatures a calculated pressure of 5 8 gpa at t 1500 k using our newly determined thermoelastic parameters appears to be more consistent with diamond forming conditions compared to the higher pressures that range up to 6 8 gpa at t 1500 k which are obtained using thermoelastic data in the literature

eclogitic inclusions in diamonds evidence of complex mantle processes over time the first ion probe trace element analyses of clinopyroxene garnet pairs both included within diamonds and from the eclogite host xenoliths are reported these diamondiferous eclogites are from the udachnaya and mir kimberlite pipes yakutia russia the major and trace element analyses of these diamond inclusion and host rock pairs are compared in order to determine the relative ages of the diamonds confirm or deny genetic relationships between the diamonds and the eclogites evaluate models of eclogite petrogenesis and model igneous processes in the mantle before during and after diamond formation the most striking aspect of the chemical compositions of the diamond inclusions is the diversity of relationships with their eclogite hosts no single distinct pattern of variation from diamond inclusion minerals to host minerals is found for all four samples garnet and clinopyroxene inclusions in the diamonds from two samples u 65 3 and u 66 3 have lower mg s lower mg and higher fe contents and lower lree than those in the host eclogite we interpret such variations as due to metasomatism of the host eclogite after diamond formation one sample u 41 3 shows enrichment in diamond inclusion mree enrichment relative to the eclogite host and may indicate a metasomatic event prior to or during diamond formation bulanova 2 found striking differences between inclusions taken from within different portions of the very same diamond clinopyroxene inclusions taken from the central early portions of yakutian diamonds were lower in mg and mg contents by up to 25 than those later inclusions at the rims of diamonds these trends are parallel to those between diamond inclusions and host eclogites determined for four of the five samples from the present study and may merely represent changing magmatic and or p t conditions in the mantle garnet trace element compositions are similar in relative proportions but variable in abundances between diamond inclusions and host eclogites this is probably due to the rapid diffusion of trace elements in garnet under mantle temperatures and consequent alteration of the garnet and not due to juvenile diamonds locking in source heterogeneities c f 3 trace element compositions of clinopyroxenes included in diamonds are generally similar to those in the host eclogite however one host clinopyroxene does show enrichment in the lree compared to that in the inclusion and may be attributed to mantle metasomatism not related to kimberlite transport in another eclogite m 46 the host clinopyroxene is depleted in the lree and fe and enriched in the hree and mg relative to the inclusion and is consistent with partial melting of the eclogite subsequent to diamond formation smnd ratios in clinopyroxenes appear to be little affected by these processes for most samples allowing sm nd isotopic studies to yield important information about ancient protoliths eclogitic mineral inclusions in yakutian diamonds appear consanguineous with the diamonds a contention supported by the observations of bulanova 2 therefore re os whole rock and smnd clinopyroxene age determinations of the udachnaya eclogites also yield the time of diamond formation approximately 2 9 ga 32 33

evidence of regional subsidence and associated interior wetland loss induced by hydrocarbon production gulf coast region usa analysis of remote images elevation surveys stratigraphic cross sections and hydrocarbon production data demonstrates that extensive areas of wetland loss in the northern gulf coast region of the united states were associated with large volume fluid production from mature petroleum fields interior wetland losses at many sites in coastal louisiana and texas are attributed largely to accelerated land subsidence and fault reactivation induced by decreased reservoir pressures as a result of rapid or prolonged extraction of gas oil and associated brines evidence that moderately deep hydrocarbon production has induced land surface subsidence and reactivated faults that intersect the surface include 1 close temporal and spatial correlation of fluid production with surficial changes including rapid subsidence of wetland sediments near producing fields 2 measurable offsets of shallow strata across the zones of wetland loss 3 large reductions in subsurface pressures where subsidence rates are high 4 coincidence of orientation and direction of displacement between surface fault traces and faults that bound the reservoirs and 5 accelerated subsidence rates near producing fields compared to subsidence rates in surrounding areas or compared to geological rates of subsidence based on historical trends subsidence rates in the gulf coast region near producing fields most likely will decrease in the future because most petroleum fields are nearly depleted alternatively continued extraction of conventional energy resources as well as potential production of alternative energy resources geopressured geothermal fluids in the gulf coast region could increase subsidence and land losses and also contribute to inundation of areas of higher elevation

the effect of metastable pyroxene on the slab dynamics seismic studies show that some subducting slabs penetrate straight into the lower mantle whereas others seem to flatten near the base of the mantle transition zone slab stagnation is often attributed to an increase in viscosity and phase transformations in the olivine system however recent mineral physics studies showed that due to extremely low transformational diffusion rates low density metastable pyroxene may persist into the transition zone in cool slabs here we use a dynamically fully self consistent subduction model to investigate the influence of metastable pyroxene on the dynamics of subducting oceanic lithosphere our results show that metastable pyroxene affects slab buoyancy at least as much as olivine metastability however unlike metastable olivine which can inhibit slab penetration in the lower mantle only for cold old and fast slabs metastable pyroxene is likely to also affect sinking of relatively young and slow slabs

time dependent model of creep on the hayward fault from joint inversion of 18 years of insar and surface creep data 1 spatial and temporal variations of aseismic fault creep influence the size and timing of large earthquakes along partially coupled faults to solve for a time dependent model of creep on the hayward fault we invert 18 years of surface deformation data 1992 2010 obtained by interferometric processing of 52 and 50 sar images acquired by the ers1 2 and envisat satellites respectively and surface creep data obtained at 19 alinement and 4 creepmeter stations for multi temporal analysis of the sar data we developed a method for identifying stable pixels using wavelet multi resolution analysis we also implement a variety of wavelet based filters for reducing the effects of environmental artifacts using a reweighted least squares approach we inverted the interferometric data to generate a time series of surface deformation over the san francisco bay area with a precision of better than a few millimeters to jointly invert the insar displacement time series and the surface creep data for a time dependent model of fault creep we use a robust inversion approach combined with a kalman filter the time dependent model constrains a zone of high slip deficit that may represent the locked rupture asperity of past and future m 7 earthquakes we identify several additional temporal variations in creep rate along the hayward fault the most important one being a zone of accelerating slip just northwest of the major locked zone we estimate that a slip rate deficit equivalent to mw 6 3 6 8 has accumulated on the fault since the last event in 1868

composition of the upper mantle geophysical tests of two petrological models the elastic properties of candidate mantle phases are used to test the viability of olivine rich pyrolitic and cao al 2o 3 rich eclogitic assemblages for the mantle high temperature adiabats for each phase of interest are constructed and compared to mantle seismic properties both pyrolitic and eclogitic assemblages satisfy the seismic properties between 200 and 400 km between 400 and 670 km depth an eclogitic assemblage yields a superior match to velocities and velocity gradients the 400 km seismic discontinuity may represent a chemical boundary between pyrolite and picritic eclogite piclogite or phase transformations in the olivine orthopyroxene components of a piclogitic assemblage containing about 16 olivine high velocity gradients in the transition zone may be explained by the transformation of ca rich cpx to majorite garnet seismic properties at the top of the lower mantle are consistent with pyrolite piclogite or perovskite implying that the 670 km discontinuity may be a chemical boundary

aseismic deformation across the hilina fault system hawaii revealed by wavelet analysis of insar and gps time series abstract the hilina fault system hfs is located on the south flank of kilauea volcano and is thought to represent the surface expression of an unstable edifice sector that is active during seismic events such as the 1975 kalapana earthquake despite its potential for hazardous landsliding and associated tsunamis no fault activity has yet been detected by means of modern geodetic methods since the 1975 earthquake we present evidence from individual sar interferograms as well as cluster analysis and wavelet analysis of gps and insar time series which suggest an inferred differential motion at hfs to investigate the effect of atmospheric delay on the observed differential motion we implement a statistical approach using wavelet transforms we jointly analyze insar and continuous gps deformation data from 2003 to 2010 to estimate the likelihood that the subtle time dependent deformation signal about the hfs scarps is not associated with the atmospheric delay this integrated analysis reveals localized deformation components in the insar deformation time series that are superimposed on the coherent motion of kilauea s south flank the statistical test suggests that at 95 confidence level the identified differential deformation at hfs is not due to atmospheric artifacts since no significant shallow seismicity is observed over the study period we suggest that this deformation occurred aseismically

space geodesy subsidence and flooding in new orleans a subsidence map of the city offers insight into the failure of the levees during hurricane katrina

preliminary studies on the offshore occurrences of monazite bearing heavy mineral placers southwestern sri lanka abstract this preliminary study deals with the grain size parameters and the mineralogy of bottom sediments off southwestern sri lanka the sediments are predominantly terrigenous and are stream derived in general the surface sediments are fine to very fine sand and coarse silt moderately and poorly sorted and negatively skewed heavy minerals make up 4 13 of the samples and are mainly composed of ilmenite monazite zircon rutile and garnet the heavy minerals contain from 0 3 to 2 8 monazite and the high concentrations are associated with the sandy silt sediments the heavy mineral assemblages found in the bottom sediments correspond with those expected from the precambrian metamorphic and intrusive rocks exposed in the adjacent hinterland the fine grain size and rounded shape of monazite from offshore sediments indicate a distant source for monazite compared to the predominantly localized source of monazite for beach placers

land subsidence in houston texas measured by radar interferometry and constrained by extensometers 1 we present results from a radar interferometry study over the houston galveston texas gulf coast region from the nearly 60 potential interferograms considered an atmospheric artifact assessment is performed and a tractable set of interferograms selected for detailed processing and error analysis the subsequent interferogram time series spanning 1996 1998 is constrained by coincident extensometer data with root mean square error less than 2 5 mm the interferogram time series confirms that historic subsidence in east houston has stopped consistent with current groundwater use patterns broad scale subsidence bowls are observed in west and northwest houston where maximum subsidence rates are in excess of 2 and 4 cm yr 1 respectively linear interferogram phase signatures associated with approximately 1 cm of differential subsidence across faults including the long point fault in northwest houston are observed near the seabrook extensometer a hereto unidentified subsidence bowl with a maximum subsidence rate in excess of 3 cm yr 1 is revealed this study demonstrates that when used in conjunction with a set of traditional geodetic measurements radar interferometry can measure the spatial and temporal evolution of urban land subsidence within even the most challenging of environments

reconstruction of the variability of the southwest monsoon during the past 3 ka from the continental margin of the southeastern arabian sea from temporal variation in 18o in globigerinoidesruber and g sacculifer and geochemical indices of weathering erosion chemical index of alteration al and ti we infer rapid southwest monsoon swm deterioration with dwindling fluvial and detrital fluxes at ca 450 650 1000 and 1800 2200 cal a bp during the late holocene we have evaluated the role of solar influx reconstructed and high latitude climate variability archived in grip and gisp 2 cores on swm precipitation broadly our 18o climate reconstruction is concordant with grip and gisp 2 and supports a teleconnection through atmospheric connection between the swm and the north atlantic climate albeit temporal extents of the little ice age and medieval warm period from high latitude are not entirely coeval moreover there is a humid climate and enhanced precipitation during the terminal stages of the little ice age the medieval warming ca ad 800 1300 is not synchronous either and is punctuated by an arid event centred at 1000 a bp although the delineation of the specific influence of solar influx on swm precipitation is elusive we surmise that swm precipitation is a complex phenomenon and local orography along southwestern india may have a role on the entrapment of moisture from the southwest trade winds when these hit land copyright 2009 john wiley sons ltd

stagnation of subducting slabs in the transition zone due to slow diffusion in majoritic garnet subducting slabs of oceanic lithosphere often stagnate before reaching the lower mantle laboratory experiments under high pressures and temperatures show that pyroxene a common mineral in such slabs is transformed to its dense high pressure counterpart majorite garnet at a very slow rate temporarily keeping the slabs buoyant compared to the surrounding mantle

land subsidence in houston correlated with flooding from hurricane harvey abstract hurricane harvey caused unprecedented flooding and socioeconomic devastation in eastern texas with high winds elevated storm tide and record rainfall the flooded area is mapped using the radar backscattering difference between sentinel 1a b satellite acquisitions spanning the event which provides a snapshot of standing water at the time of image acquisition we find vast areas outside of designated flood hazard zones are overwhelmed furthermore we map pre cyclone land subsidence using multitemporal interferometric processing of large sar datasets acquired by advanced land observation satellite alos and sentinel 1a b satellites we find that subsidence of up to 49 mm yr and 34 mm yr during the alos jul 2007 jan 2011 and sentinel 1a b dec 2015 to aug 2017 acquisition periods affect various parts of houston galveston area we conclude that 85 of the flooded area subsided at a rate 5 mm yr we suggest that subsidence affected flood severity by modifying base flood elevations and topographic gradients supported by the chi square test of independence this work highlights the importance of incorporating insar measurements of land subsidence in flood resilience strategies

mapping ground deformation over houston galveston texas using multi temporal insar abstract houston galveston hg region in texas has been subsiding due to the combined effects of groundwater withdrawal hydrocarbon extraction salt dome movement and faulting this human and partially nature induced ground deformation has gradually threatened the stability of urban infrastructure and caused the loss of wetland habitat along the gulf of mexico interferometric synthetic aperture radar insar techniques can measure ground motions in high spatial resolution over large coverage the purpose of this study is to map the spatial and temporal variations in surface deformation around the hg region using a multi temporal insar mti technique and to assess the role of fluid withdrawal groundwater withdrawal and hydrocarbon extraction salt tectonics and fault activity in land surface deformation mti derived land surface deformation measurements are then compared to gps and extensometer observations geologic and hydrologic data and information about hydrocarbon extraction to address the causes of the observed deformation the mti measurements based on ers 1 2 datasets have mapped regional subsidence up to 53 mm yr in the northwestern hg as well as a slight uplift at 20 mm yr in the southeastern hg from 1993 to 2000 insar measurements obtained from envisat and alos data reveal subsidence rate of up to 30 mm yr over the northwestern hg between 2004 and 2011 our results indicate that the pattern of ground deformation was nearly concentric around locations of intense groundwater withdrawal and the spatial extent of the subsiding area has been shrinking and migrating toward the northeast after 2000 we have resolved localized ground subsidence cones over hydrocarbon exploration fields which were likely caused by reservoir compaction we have differentiated ground surface deformation over salt domes which was due to ongoing differential movement of individual salt spines we have identified 5 40 mm yr differential subsidence across a number of faults in the region these faults functioned as water barriers disrupting the integrity of ground water flow and aggravating localized surface displacements

slow si al interdiffusion in garnet and stagnation of subducting slabs abstract si 4 m 2 2al 3 m mg fe ca interdiffusion rates in majoritic garnet have been determined at pressure of 17 gpa and temperatures of 1550 1700 c using a kawai type high pressure apparatus the diffusion profiles were measured across the interface between pyropic garnet and majoritic garnet samples by an analytical transmission electron microscope and the rate of the si 4 m 2 2al 3 interdiffusion was determined to be a d si al m 2 s 1 2 10 10 exp 364 kj mol 1 rt we found that the diffusion rate is low compared to the si diffusion rate in other silicate minerals relevant to the deep mantle slow kinetics of the pyroxene garnet transformation due to the low diffusion rate indicates that large low density metastable regions may exist in the slab greatly contributing to the slab stagnation around the transition region stagnant slabs possibly stay in this region over 10 8 yr because of the sluggish pyroxene garnet transformation but may eventually fall into the lower mantle after the completion of the transformation

applicability of sentinel 1 terrain observation by progressive scans multitemporal interferometry for monitoring slow ground motions in the san francisco bay area 2017 american geophysical union all rights reserved data from the sentinel 1 satellite have already proven useful for investigating seismic and volcanic events since its launch in april 2014 the requirement of ultrahigh coregistration accuracy and the current relatively short time of sentinel 1 acquisitions make its application challenging for studying slow deformation processes such as fault creep and land subsidence here we analyze a set of 14 sar images over the san francisco bay area spanning 1 year from early 2015 to 2016 we show that implementing an existing enhanced spectral diversity algorithm or using precise orbits together with a reference digital elevation model both yield the required coregistration accuracy for making use of the phase measurements in time series analysis of ground deformation following a thorough validation test we update our estimates of hayward fault creep rate and confirm uplift due to recharge of the santa clara valley aquifer system during the final summer of 4 year drought

aquifer mechanical properties and decelerated compaction in tucson arizona in recent decades high groundwater extraction rates often coincident with periods of severe drought result in the widespread decline of water levels overexploitation of aquifers also causes land subsidence which poses a severe threat to infrastructure tucson arizona experiences land subsidence coupled with the depletion of groundwater a critical water resource for the desert city to understand the spatiotemporal evolution of land subsidence and its implications for aquifer properties we examine long time series of surface deformation and head levels measurements at extensometer stations indicate rapid compaction of fine grained material up to 8 5 mm yr from 1990 to 2005 which results in permanent storage volume losses up to 4 1 the analysis of densely populated sets of interferograms generated from envisat and radarsat c band acquisitions yields multitemporal maps of surface deformation at unprecedented resolution these maps reveal that subsidence significantly slows by the late 2000s corresponding with the implementation of artificial recharge efforts subsequent to groundwater level recovery we observe a brief 6 6 year interval of residual compaction suggesting a high vertical hydraulic conductivity which is then shown to be up to 9 8x10 4 m day we also estimate the average elastic and inelastic skeletal storage coefficients for the aquifer system to be 3 78x10 3 and 6 01x10 3 respectively insar shows deformation nearly ceases by 2015 likely reducing hazards associated with earth fissuring and infrastructure damage this study highlights successful outcomes of water management and conservation plans that preserve existing groundwater reserves and increase artificial recharge

elasticity of single crystal iron bearing pyrope up to 20 gpa and 750 k abstract elastic properties of the major constituent minerals in the earth s upper mantle at relevant high pressure temperature p t conditions are crucial for understanding the composition and seismic velocity structures of this region in this study for the first time we have measured the single crystal elasticity of natural fe bearing pyrope mg 2 04 fe 0 74 ca 0 16 mn 0 05 al 2 si 3 o 12 using in situ brillouin spectroscopy and x ray diffraction at simultaneous high p t conditions up to 20 gpa and 750 k in an externally heated diamond anvil cell the derived aggregate adiabatic bulk and shear moduli k s 0 g 0 at ambient conditions are 168 2 1 8 gpa the value in parentheses represents propagated uncertainties 1 and 92 1 1 1 gpa respectively consistent with literature results using the third order eulerian finite strain equation to model the high p t data the derived pressure derivatives of the bulk and shear moduli at constant temperature are k s p t 4 4 0 1 and g p t 1 2 0 1 respectively whereas the temperature derivatives of these moduli at constant pressure are k s t p 16 8 1 3 mpa k and g t p 5 1 1 1 mpa k respectively compared to literature values our results show that addition of 25 mol fe in pyrope increases the pressure derivative of the bulk modulus by 7 but has a negligible effect on other elastic parameters extrapolation of our results shows that fe bearing pyrope remains almost elastically isotropic at relevant p t conditions of the upper mantle indicating that it may not have a significant contribution to seismic v p and v s anisotropy in the upper mantle together with the elasticity of olivine and pyroxene minerals in the upper mantle we have constructed new velocity profiles for two representative compositional models pyrolite and piclogite along a representative geotherm of the earth s upper mantle these velocity models show v s profiles consistent with seismic observations although v p profiles are slightly lower than global seismic observations our analyses also show that approximately 30 garnet in a mineralogical model is needed to best match both seismic v p and v s profiles of the region although such high garnet content needs to be reconciled with our current geochemical understanding our results here provide new insights into seismic profiles and mineralogical models of the upper mantle region