topography relief and trmm derived rainfall variations along the himalaya 1 along the southern himalayan topographic front the indian summer monsoon modulates erosive processes and rates to investigate the influence of topography and relief on rainfall generation and resultant erosion we processed satellite rainfall amounts for the last 8 years 1998 2005 from the tropical rainfall measurement mission trmm based upon a spatial resolution of 5 5 km for the himalaya we identify 1 the spatial distribution of rainfall and 2 the large scale relationships between topography relief and rainfall locations our results show two distinct rainfall maxima along strike in the himalaya the first outer rainfall peak occurs along the southern margin of the lesser himalaya within a narrow band of mean elevation 0 9 0 4 km and mean relief 1 2 0 2 km the second discontinuous inner band typically occurs along the southern flank of the greater himalaya elevation and relief both 2 1 0 3 km

boron in chert and precambrian siliceous iron formations abstract in order to assess the importance of siliceous sediments as a sink for oceanic b and to determine the effect of diagenesis on the mobilization of b samples were analysed from chert nodules bedded cherts and siliceous banded iron formations from a variety of sedimentary environments and geologic ages boron analyses on bulk samples were made by prompt gamma neutron activation analysis the distribution of b in rocks was mapped using track methods nodular phanerozoic cherts typically contain 50 150 ppm b and bedded cherts somewhat less the b is initially concentrated in tests of silica secreting organisms but some is lost in early diagenesis as silica progressively recrystallises to quartz banded iron formation silica of archean and proterozoic age usually contains

contrasting behaviour of boron during crustal anatexis the study of volatile elements in crustal anatectic terranes may provide information about the role of fluid flow and fluid pathways during high temperature metamorphism we have studied the distribution of li and b in two migmatitic areas the pena negra anatectic complex central spain and the migmatites and leucogranites associated with the ronda peridotites southern spain they represent two contrasting cases in the behaviour of volatiles particularly b during anatexis the pena negra migmatites are dominated by diatexites where it is possible to distinguish granitic leucosomes melanosomes metric to decimetric leucogranitic segregates and decimetric to metric sillimanite rich restitic enclaves all lithologies are characterized by low b concentrations mean values 30 ppm and b is enriched in melanosomesrrestites with respect to leucosomesrleucogranites this may be due to the fact that a notable proportion of b can reside in restitic sillimanite b concentrations in leucosomes and leucogranites can be explained by closed system anatexis at ronda metatexitic and diatexitic migmatites underlie the ronda peridotites and diatexite and leucogranite dikes intrude the peridotites diatexites underlying the peridotites are characterized by cordierite q biotite garnet as ferromagne sian phases with rare or absent tourmaline low b contents 10 ppm and cordierite garnet leucosomes leucogranite dikes have high b concentrations mean valuef 400 ppm with tourmaline being a common and sometimes the most abundant ferromagnesian phase a genetic relationship between diatexites and leucogranites is strongly suggested by the presence of dikes of diatexites intruding the bottom of the peridotites we conclude that b in the leucogranites may stem from the dissolution of tourmaline originally present in the metasediments or infiltration of b rich aqueous fluids into the anatectic zone according to recent experimental work textures in some tourmaline rich ronda leucogranites suggest initial b o 23 contents in the melt higher than the present measured concentrations preliminary experimental results presented in this paper propose that this difference is not due to water activities in the melt rapid crystallization of the melts following undercooling may explain the existence of abundant euhedral tourmaline in leucogranites with low aluminium saturation index asis molar al o r caoq na oq k o and relatively low b contents q 2001 elsevier science b v all rights 23 2 2 reserved

holocene aridification of india 1 spanning a latitudinal range typical for deserts the indian peninsula is fertile instead and sustains over a billion people through monsoonal rains despite the strong link between climate and society our knowledge of the long term monsoon variability is incomplete over the indian subcontinent here we reconstruct the holocene paleoclimate in the core monsoon zone cmz of the indian peninsula using a sediment core recovered offshore from the mouth of godavari river carbon isotopes of sedimentary leaf waxes provide an integrated and regionally extensive record of the flora in the cmz and document a gradual increase in aridity adapted vegetation from 4 000 until 1 700 years ago followed by the persistence of aridity adapted plants after that the oxygen isotopic composition of planktonic foraminiferglobigerinoides ruberdetects unprecedented high salinity events in the bay of bengal over the last 3 000 years and especially after 1 700 years ago which suggest that the cmz aridification intensified in the late holocene through a series of sub millennial dry episodes cultural changes occurred across the indian subcontinent as the climate became more arid after 4 000 years sedentary agriculture took hold in the drying central and south india while the urban harappan civilization collapsed in the already arid indus basin the establishment of a more variable hydroclimate over the last ca 1 700 years may have led to the rapid proliferation of water conservation technology in south india

chemical and sr isotopic variations during diagenesis of miocene siliceous sediments of the monterey formation california the monterey formation of california preserves miocene siliceous sediments at progressive generally with depth diagenetic stages diatomite opal a ct chert opai ct quartz chert for initially clay poor sediments and diatomaceous shale ct porcelanite porous opal ct quartz porcelanite for sediments that were initially clay rich the chemistry of most diatomite is controlled by three primary phases biogenic silica carbonate and detrital clay and several subsidiary phases organic material apatite pyrite and detrital minerals including quartz and plagioclase the elemental abundances of the clay poor diagenetic sequence decrease sharply with advancing diagenetic state for those elements controlled by clay al ti k rb cs fe some group b metals carbonate ca mg sr ba apatite p ca sr ba v and organics v ni while silica shows a congruent increase these first order variations reflect the initial compositions of the siliceous sediments modified by the addition of silica the removal of carbonate and apatite and the migration of petroleum during silica diagenesis anomalous abundances of mn ni cr mo and some other group b metals are associated with trapped refractory organic material and suggest that petroleum catagenesis and migration occurred during silica diagenesis migration may have been facilitated by the release of bound water during silica dehydration reactions second order variations in k rb k cs rb sr 87 sr 86 sr with advancing diagenetic state suggest ion exchange and ion expulsion by reaction of detrital phases with pore fluids diagenetic processes partially equilibrated but did not homogenize depositional 87 rb 86 sr 87 sr 86 sr mixing lines generated by detrital clays and authigenic carbonate and silica in siliceous sediments from the santa maria region however similar mixing lines in diatomites from the santa lucia area are reset to nearly horizontal slopes in associated ct porcelanites the degree of equilibration may be a function of the rate of formation of relatively impermeable quartz chert which isolated the siliceous system from further interaction with pore fluids the rapid formation of quartz chert in the santa maria region is believed to have prevented isotopic homogenization processes from reaching completion initial chemistry of the siliceous systems controlled the rates and pathways of silica diagenesis silica diagenesis in turn altered the chemistry of the siliceous sediment

geochemistry of archean shales from the pilbara supergroup western australia archean clastic sedimentary rocks are well exposed in the pilbara block of western australia shales from turbidites in the gorge creek group ca 3 4 ae and shales from the whim creek group ca 2 7 ae have been examined the gorge creek group samples characterized by muscovite quartzchlorite mineralogy are enriched in incompatible elements k th u lree by factors of about two when compared to younger archean shales from the yilgarn block alkali and alkaline earth elements are depleted in a systematic fashion according to size when compared with an estimate of archean upper crust abundances this depletion is less notable in the whim creek group such a pattern indicates the source of these rocks underwent a rather severe episode of weathering the gorge creek group also has fairly high b content 85 29 ppm which may indicate normal marine conditions during deposition rare earth element ree patterns for the pilbara samples are characterized by light ree enrichment lanybn 7 5 and no or very slight eu depletion eueu 0 82 0 99 a source comprised of about 80 felsic igneous rocks without large negative eu anomalies felsic volcanics tonalites trondhjemites and 20 mafic ultramafic volcanics is indicated by the trace element data very high abundances of cr and ni cannot be explained by any reasonable provenance model and a secondary enrichment process is called for

the boron isotope systematics of the yellowstone national park wyoming hydrothermal system a reconnaissance abstract boron concentrations and isotope compositions have been measured in fourteen hot spring waters two drill hole waters an unaltered rhyolite flow and hydrothermally altered rhyolite from the geothermal system in yellowstone national park wyoming the samples are representative of the major thermal areas within the park and span the range of fluid types for the fluids the b concentrations range from 0 043 2 69 mm kg and the 11 b values range from 9 3 to 4 4 there is no relationship between the dissolved b concentrations or isotope compositions with the concentration of any major element other than cl or physical property each basin is characterized by a restricted range in b cl ratios and 11 b values hot spring waters from the morris basin upper geyser basin calcite springs and clearwater have 11 b values close to that of unaltered rhyolite 5 2 and are interpreted to have derived their b from this source waters from mammoth hot springs sheepeater and rainbow springs have lower 11 b values close to 8 these lower values may reflect leaching of b from sedimentary rocks outside the yellowstone caldera but they are similar to the 11 b value of hydrothermally altered rhyolite 9 7 hence the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals cooler springs along the yellowstone river just outside the park boundary have lower b concentrations and higher 11 b values that may reflect mixing with shallow meteoric water

understanding erosion rates in the himalayan orogen a case study from the arun valley understanding the rates and pattern of erosion is a key aspect of deciphering the impacts of climate and tectonics on landscape evolution denudation rates derived from terrestrial cosmogenic nuclides tcns are commonly used to quantify erosion and bridge tectonic myr and climatic up to several kiloyears time scales however how the processes of erosion in active orogens are ultimately reflected in 10be tcn samples remains a topic of discussion we investigate this problem in the arun valley of eastern nepal with 34 new 10be derived catchment mean denudation rates the arun valley is characterized by steep north south gradients in topography and climate locally denudation rates increase northward from 0 2 mm yr 1 to 1 5 mm yr 1 in tributary samples while main stem samples appear to increase downstream from 0 2 mm yr 1 at the border with tibet to 0 91 mm yr 1 in the foreland denudation rates most strongly correlate with normalized channel steepness r2 0 67 which has been commonly interpreted to indicate tectonic activity significant downstream decrease of 10be concentration in the main stem arun suggests that upstream sediment grains are fining to the point that they are operationally excluded from the processed sample this results in 10be concentrations and denudation rates that do not uniformly represent the upstream catchment area we observe strong impacts on 10be concentrations from local nonfluvial geomorphic processes such as glaciation and landsliding coinciding with areas of peak rainfall rates pointing toward climatic modulation of predominantly tectonically driven denudation rates

strain offsets with monotonous damped oscillations during the 1986 izu oshima volcano eruption the sequential process of the 1986 izu oshima volcano eruption japan was recorded by a volumetric strain meter near the erupted summit the records show occasional strain offsets accompanying long period damped oscillations which we interpret as responses of the volcanic system to perturbations in magmatic pressure the polarities of strain offsets were contractive for all events before the enormous ground deformation of november 21 due presumably to the intensive dike intrusion on the contrary all events after that had expansive polarities the characteristic frequencies of oscillations were 42 6 mhz for the events before changing abruptly to half that after the ground deformation in our model which is a one dimensional magma filled conduit the boundary condition at the top of the conduit changed from a closed to an open end upon a void formation at the top of the magma head due to its descent immediately after the dike intrusion before the magma escape from the reservoir as a dike magma was episodically supplied from the reservoir to the conduit and thus contraction events were generated after the magma escape magma left in the conduit was episodically drained back to the reservoir to generate expansion events this episodic magma supply or drainage was modeled by a prescribed pressure change at the bottom of the conduit we solved the free oscillation problem of the conduit pipe with an elastic sidewall to calculate the resultant volumetric strain outside the pipe physical properties of the magma and the excitation mechanism are inferred from the application of our formulation to the observation the conduit length and fluid acoustic velocity are estimated to be 10 km and 430 m s respectively suggesting that the fluid is composed of a gas liquid mixture if the conduit radius is taken to be 40 m and if the damping of oscillation occurred by viscous dissipation the fluid viscosity is 108 109 pa s a reasonable estimate for the basaltic magma the applied pressure changes at the bottom of the conduit are in a range from 105 to 106 pa with risetimes of the order of 4 to 100 s

precipitation variability in the indian central himalaya during last ca 4 000 years inferred from a speleothem record impact of indian summer monsoon ism and westerlies abstract we report the first high resolution stalagmite record from indian central himalaya by using a combined oxygen and carbon isotopic study spanning the last 4000 years in addition to the multi decadal events the stalagmite data also provide information on the variability in the intensity of precipitation indian summer monsoon ism and westerlies in north indian hills during the late holocene the 18o values show strong variability between 2 1 and 8 9 the extremely high variability points to the monsoon from two different sources compared to other similar aged caves which are primarily controlled by one monsoon such as the east asian summer monsoon easm although ism has penetrated into some parts in the areas of easm in the past or the westerlies therefore we suggest that the westerlies played an important role in the late holocene climate of the indian himalaya as the source of the westerlies is mediterranean atlantic the north atlantic oscillation nao which was responsible for comparatively stronger westerlies in southern europe may have brought higher precipitation to the north indian hills the stronger westerlies may also have resulted in the highest precipitation between 0 5 and 0 25 ka bp 1450 1700 ad a part of the lia in contrast to the weakening of the indian summer monsoon ism in peninsular india the stalagmite has also recorded the driest period peaking at 3 2 ka bp which may be nearly synchronous with the final collapse of the harappan culture in northwest india

monsoon source shifts during the drying mid holocene biomarker isotope based evidence from the core monsoon zone cmz of india abstract a better understanding of past variations of the indian summer monsoon ism that plays a vital role for the still largely agro based economy in india can lead to a better assessment of its potential impact under global climate change scenarios however our knowledge of spatiotemporal patterns of ism strength is limited due to the lack of high resolution continental paleohydrological records here we reconstruct centennial scale hydrological variability during the holocene associated to changes in the intensity of the ism based on a record of lipid biomarker abundances and compound specific stable isotopic composition of a 10 m long sediment core from saline alkaline lonar lake situated in the core monsoon zone of central india we identified three main periods of distinct hydrology during the holocene in central india the period between 10 1 and 6 cal ka bp was likely the wettest during the holocene lower average chain length acl index values 29 4 28 6 and negative 13 c wax values 34 8 to 27 8 of leaf wax n alkanes indicate the dominance of woody c 3 vegetation in the catchment and negative d wax values concentration weighted average 171 to 147 suggest a wet period due to an intensified monsoon after 6 cal ka bp a gradual shift to less negative 13 c wax values particularly for the grass derived n c 31 and appearance of the triterpene lipid tetrahymanol generally considered as a marker for salinity and water column stratification mark the onset of drier conditions at 5 1 cal ka bp an increasing flux of leaf wax n alkanes along with the highest flux of tetrahymanol indicate a major lowering of the lake level between 4 8 and 4 cal ka bp we find evidence for a transition to arid conditions indicated by high and strongly variable tetrahymanol flux in addition a pronounced shift to less negative 13 c wax values in particular for n c 31 25 2 to 22 8 during this period indicates a change of dominant vegetation to c 4 grasses in agreement with other proxy data such as deposition of evaporite minerals we interpret this period to reflect the driest conditions in the region during the last 10 1 ka this transition led to protracted late holocene arid conditions after 4 ka with the presence of a permanent saline lake supported by the sustained presence of tetrahymanol and more positive average d wax values 122 to 141 a late holocene peak of cyanobacterial biomarker input at 1 3 cal ka bp might represent an event of lake eutrophication possibly due to human impact and the onset of cattle livestock farming in the catchment a unique feature of our record is the presence of a distinct transitional period between 4 8 and 4 cal ka bp which was characterized by some of the most negative d wax values during the holocene up to 180 when all other proxy data indicate the driest conditions during the holocene these negative d wax values can as such most reasonably be explained by a shift in moisture source area and or pathways or rainfall seasonality during this transitional period we hypothesize that orbital induced weakening of the summer solar insolation and associated reorganization of the general atmospheric circulation as a possible southward displacement of the tropical rainbelt led to an unstable hydroclimate in central india between 4 8 and 4 ka our findings shed light onto the sequence of changes during mean state changes of the monsoonal system once an insolation driven threshold has been passed and show that small changes in solar insolation can be associated with major hydroclimate changes on the continents a scenario that may be relevant with respect to future changes in the ism system

minimal alteration of montmorillonite following long term interaction with natural alkaline groundwater implications for geological disposal of radioactive waste bentonite is one of the more safety critical components of the engineered barrier system in the disposal concepts developed for many types of radioactive waste bentonite is utilised because of its favourable properties which include plasticity swelling capacity colloid filtration low hydraulic conductivity high retardation of key radionuclides and stability in geological environments of relevance to waste disposal however bentonite is unstable under the highly alkaline conditions induced by ordinary portland cement opc initial porewater ph 13 and this has driven interest in using low alkali cements initial porewater ph9 11 as an alternative to opc to build a robust safety case for a repository for radioactive wastes it is important to have supporting natural analogue data to confirm understanding of the likely long term performance of bentonite in these lower alkali conditions in cyprus the presence of natural bentonite in association with natural alkaline groundwater permits the zones of potential bentonite alkaline water reaction to be studied as an analogy of the potential reaction between low alkali cement leachates and the bentonite buffer in the repository here the results indicate that a cation diffusion front has moved some metres into the bentonite whereas the bentonite reaction front is restricted to a few millimetres into the clay this reaction front shows minimal reaction of the bentonite volumetrically less than 1 of the bentonite with production of a palygorskite secondary phase following reaction of the primary smectites over time periods of 105 106 years

the generation and crystallization conditions of the proterozoic harney peak leucogranite black hills south dakota usa petrologic and geochemical constraints the mineralogy petrology and geochemistry of the proterozoic harney peak granite black hills south dakota were examined in view of experimentally determined phase equilibria applicable to granitic systems in order to place constraints on the progenesis of peraluminous leucogranites and commonly associated rare element pegmatites the granite was emplaced at 3 4 kbar as multiple sills and dikes into quartz mica schists at the culmination of a regional high temperature low pressure metamorphic event principally along the periphery of the main pluton and in satellite intrusions the sills segregated into granite pegmatite couplets the major minerals include quartz k feldspar sodic plagioclase and muscovite biotite mg no molar mgo mgo feo 0 32 0 38 is the predominant ferromagnesian mineral in the granite s core whereas at the periphery of the main pluton and in the satellite intrusions tourmaline mg no 0 18 0 48 is the dominant ferromagnesian phase almandine spessartine garnet is also found in the outer intrusions there is virtually a complete overlap in the wide concentration ranges of sio2 cao mgo feo sr zr w of the biotite and tourmaline bearing granite suites with no discernable differentiation trends on harker diagrams precluding the derivation of one suite from the other by differentiation following emplacement this is consistent with the oxygen isotope compositions which are 11 5 0 6 for the biotite granites and 13 2 0 8 for the tourmaline granites suggesting derivation from different sources the concentrations of tio2 and possibly ba are higher and of mno and b are lower in the biotite granites the normative orthoclase albite ratio is extremely variable ranging from 0 26 to 1 65 in the biotite granites to 0 01 1 75 in the tourmaline granites very few sample compositions fall near the high pressure watersaturated haplogranite minima eutectic trend indicating that the granites for the most part are not minimum melts generated under conditions with a text h text 2 text o 1 instead most biotite granites are more potassic than the water saturated minima and eutectics and in analogy with experimentally produced granitic melts they are best explained by melting at 6 kbar a text h text 2 text o 1 and temperatures 800 c such high temperatures are also indicated by oxygen isotope equilibration among the constituent minerals nabelek et al 1992 several of the tourmaline granite samples contain virtually no k feldspar and have oxygen isotope equilibration temperatures 716 775 c therefore they must represent high temperature accumulations of liquidus minerals crystallized under equilibrium conditions from melts more sodic than the water saturated haplogranite minima or during fractionation of intruded melts into granite pegmatite couplets accompanied by volatile aided differentiation of the alkali elements the indicated high temperatures a text h text 2 text o 1 the relatively high tio2 and ba concentrations and the relatively low partial 18 text o values of the biotite granites suggest that they were generated by high extent biotite dehydration melting of an immature archean metasedimentary source the ascent of the hot melts may have triggered low extent muscovite dehydration melting of schists higher in the crust producing the high b low ti melts comprising the periphery of the main pluton and the satellite intrusions alternatively the different granite types may be the result of melting of a vertical section of the crust in response to the ascent of a thermal pulse with the low partial 18 text o biotite granites generated at a deeper hotter region and the high partial 18 text o tourmaline granites at a higher cooler region of the crust the low ti and high b concentrations in the high partial 18 text o melts resulted in the crystallization of tourmaline rather than biotite which promoted the observed differentiation of the melts into the granitic and pegmatitic layers found along the periphery of the main pluton and the satellite intrusions

geochemistry of a chert breccia a complex history of diagenetic interactions between a siliceous sediment seawater and fresh water is revealed by intraformational chert breccias chert breccias were formed in the campanian mishash formation in israel by practically contemporaneous fracturing of lithified cherty layers followed by silicification and lithification of the matrix pairs of fragments and matrix were compared with respect to their chemical ca sr na k mg li b so4 ba and isotopic 18 o d 11 b composition 11 b was analyzed by ion probe and includes a profile across a fragment matrix contact the epicontinental cherts of the mishash fm are enriched by a factor of 10 to 50 in all elements other than o and si in comparison with deep sea cherts all results are compatible with the proposition that the lithification of the matrix occurred in contact with fresh water as opposed to seawater in which the fragments as well as most of the mishash sediments were formed the strongest evidence for this difference is in the higher concentration of b in the fragments 27 70 ppm vs 11 21ppm in the matrix and higher 18 o 29 to 35 vs 21 to 33 d is a less efficient discriminator though compatible with fresher water diagenesis of the matrix 115 to 76 for hydrogen in the chert of the fragments compared to 141 to 85 for the matrix 11 b in the matrix shows some of the lowest values recorded in sediments 11 b 33 but varies strongly suggesting that the source of boron in the matrix is a mixture of a freshwater and a marine component both seawater and the freshwater that has equilibrated with the cherts underwent varying degrees of evaporation ca sr and so4 are carried by apatite trapped as detritus in the matrix the concentration of lithium in the matrix is high 11 16 ppm whereas in the adjacent fragments it is mostly only within 1 2 ppm li probably enters the matrix from the interstitial solution during the opal 3 quartz transformation the second prolonged transformation takes place in a freshwater flow through open system this allows a much larger mass of li to be scavenged by the transforming silica despite its low concentration in freshwater copyright 2005 elsevier ltd

panigarh cave stalagmite evidence of climate change in the indian central himalaya since ad 1256 monsoon breaks and winter southern jet depressions abstract variations in petrography stable isotopes reflectance and luminescence along the central growth axis of a 14 5 cm stalagmite from panigarh cave indicate cooler and slightly wetter conditions in the himalayan foothills of northern india during the little ice age lia which lasted from ad 1489 1889 based on deposition of calcite and ad 1450 1820 based on rapid changes in 18o values conditions were warmer and drier during the preceding medieval climate anomaly mca and also in the post lia periods as evidenced by deposition of aragonite a review of currently existing stalagmite and other proxy data from south and east asia reveals a broad spatial pattern in precipitation over south and east asia during the lia with northern areas showing generally increased precipitation and southern areas reduced precipitation during the mca and after the lia the records suggest this pattern was reversed weaker ism during the lia brought drought conditions to the core ism area but triggered more monsoon breaks that brought higher precipitation to the himalayas at the same time the weaker ism may also have pushed more depressions along the path of the southern winter jet which brought more winter precipitation to the himalayas and therefore a lia wetter in our study area

climatic fluctuations during the lia and post lia in the kumaun lesser himalaya india evidence from a 400 y old stalagmite record this paper presents the first stable isotope delta o 18 and delta c 13 data of a similar to 400 years 1590 2006 ad long annual to decadal resolution speleothem record collected from the indian lesser himalaya the data show a variation from 2 7 to 5 9 parts per thousand in delta o 18 and 5 3 to 8 8 parts per thousand in delta c 13 the isotopic analyses indicate that the climate during this period can be divided into two stages a wet phase during the little ice age lia 1590 1850 ad and comparatively dry phase during the post lia after 1850 ad however the record also documents the minor dry events during the lia and a wet episode after the lia within the age uncertainty the dry spells during the lia are linked with the historical drought events in the indian subcontinent and similar latitudes the isotopic record is consistent with a number of previous studies in the areas influenced by the westerlies but appears to be conflicting to the regions dominated by the indian summer monsoon ism this may be due to the possible changes in the strength of westerlies in the study area and added by negative anomaly of north atlantic oscillation nao during the lia c 2012 elsevier ltd and inqua all rights reserved

boron metasomatism of the alta stock contact aureole utah evidence from borates mineral chemistry and geochemistry geochemical study of the alta stock and adjacent contact aureole rocks provides information concerning the source composition and physical chemical conditions of infiltrating fluids special emphasis was given to boron b as a tracer of fluid rock interactions due to the occurrence of borate minerals ludwigite kotoite and szaibelyite in skarn deposits around the stock in addition thin section alpha track mapping implies significant b enrichments in fluid altered minerals within the stock stockwork veins and related selvages igneous sills near the stock contact skarns and in marbles up to 500 m from the stock forsterite clinohumite lizardite and malachite contain between 50 and 1200 ppm b diopside calcite clintonite phlogopite brucite hedenbergite tremolite and other minerals host b to a lesser extent aureole b enrichments correlate well with major and other trace element enrichments and support existing models of element transport in magmatic fluids with lateral down temperature flow large variations in mineral b concentrations reflect changes in b concentrations of these fluids through time mass balance calculations indicate that magmatic fluids emanating from the alta pluton could supply most b in the alta aureole it is estimated that the emplaced magma had an initial b concentration between 7 10 ppm indicated exhalative losses of b from the pluton are on the order of 50 we estimate that the exsolved fluids had a time integrated b concentration of 160 40 ppm although much higher concentrations may have attended local borate mineralization

a 900 year 600 to 1500 a d record of the indian summer monsoon precipitation from the core monsoon zone of india 1 we present a near annually resolved record of the indian summer monsoon ism rainfall variations for the core monsoon region of india that spans from 600 to 1500 a d from a 230th dated stalagmite oxygen isotope record from dandak cave our rainfall reconstruction which spans the medieval warm period mwp and the earliest portion of the little ice age lia indicates that the short instrumental record of ism underestimates the magnitude of monsoon rainfall variability periods of severe drought lasting decades occurred during the 14th and mid 15th centuries and coincided with several of india s most devastating famines

behaviour of boron in the generation of an anatectic complex the pen a negra complex central spain abstract the pe na negra anatectic complex central spain was formed from a pelitic protolith low in boron 3 80 ppm by dehydration reactions melting and fluid loss which expelled much of the boron residual b is present in sillimanite and muscovite migmatite melanosomes and restites sillimanite biotite ilmenite are relatively richer in b mean 29 ppm while the leucosomes are poorer 13 ppm late shears fractures and zones of retrograde alteration have permitted some reintroduction of b experiments demonstrated that b cannot be removed from these rocks by heating or by leaching indicating that very little is present in superficial adsorption and that the element occurs in mineral structures

water balance of the indus river basin and moisture source in the karakoram and western himalayas implications from hydrogen and oxygen isotopes in river water 1 stable isotope measurements of hydrogen and oxygen for surface waters from the indus river basin irb together with historical records for river discharge annual precipitation and groundwater levels are used to assess water balance for the basin the indus river presently drains 53 km3 yr 1 or roughly one eighth of the 398 km3 water that annually falls on the basin in the form of rain and snow with the remainder returned to the atmosphere by evapotranspiration monthly samples for the indus river close to its mouth for the water year march 1994 to february 1995 show a tight correlation in d and 18o space the slope of the linear regression is 7 5 which is not significantly different from the slopes of the local meteoric water lines lmwl 7 3 and 7 1 this observation argues against significant loss of water by direct evaporation from river surfaces or from soils in hydrologic continuum with surface waters an upper limit for evaporation from poorly drained soils is calculated to be 10 km3 yr 1 or only 2 5 of the annual precipitation flux groundwater storage in the entire canal command area received a maximum of 23 km3 yr 1 or 5 8 of the annual precipitation during the early stages of irrigation but modern recharge is probably balanced by discharge to rivers and well exploitation transpiration by natural vegetation and crops annually returns 83 of the precipitation flux and constitutes the largest pathway for the loss of water from the basin deuterium excess d excess in the irb ranges between 4 and 28 with values for 95 of the sample population exceeding 10 the indus main channel close to its mouth varies in d excess between 12 and 20 during low and high water stands respectively with a discharge weighted average of 18 these values are distinctly higher than the long term average for the indian monsoon 8 and reflect contributions from water vapor originating in the mediterranean 22 or other inland seas using these end member compositions and the discharge weighted average d excess isotope balance calculations require that up to 72 of the indus discharge close to its mouth must be derived from the mediterranean end member and implies that bulk of the indus discharge is the result of delayed runoff from the karakoram and the himalayas

short term variability in the dates of the indian monsoon onset and retreat on the southern and northern slopes of the central himalayas as determined by precipitation stable isotopes this project launched the first study to compare the stable isotopes 18o and d in daily precipitation at kathmandu located on the southern slope of the central himalayas and tingri located on the northern slope the results show that low 18o and d values of summer precipitation at the two stations were closely related to intense convection of the indian monsoon however summer 18o and d values at tingri were lower than those at kathmandu a result of the lift effect of the himalayas coupled with convection disturbances and lower temperatures at tingri in winter the relatively high 18o and d values at the two stations appears to have resulted from the influence of the westerlies compared with those during the summer the subsidence of the westerlies and northerly winds resulted in relatively high 18o and d values of the winter precipitation at tingri winter 18o and d values at kathmandu far exceeded those at tingri due to more intense advection of the southern branch of the westerlies and higher temperatures and relative humidity at kathmandu the detailed differences in stable isotopes between the two stations follow short term variability in the onset date of the indian monsoon and its retreat across the central himalayas during the sampling period the indian monsoon onset at tingri occurred approximately 1 week later than that at kathmandu however the retreat at tingri began roughly 3 days earlier clearly the duration of the indian monsoon effects last longer at kathmandu than that at tingri our findings also indicate that the india monsoon travels slowly northward across the central himalayas due to the blocking of the himalayas but retreats quickly