changing features of the climate and glaciers in china s monsoonal temperate glacier region 1 climatic data ice core records the tree ring index and recorded glacier variations have been used to reconstruct a history of climatic and glacial changes in the monsoonal temperate glacier region of southwestern china during the last 400 years the region s temperature has increased in a fluctuating manner during the twentieth century after two cold stages of the little ice age seventeenth to nineteenth centuries with a corresponding retreat of most of the glaciers against a background of global warming retreat rates accelerated after the 1980s the few advancing glaciers that did exist have started to retreat in recent years the amount trend and amplitude of variation of precipitation have differed in different parts of the region the dasuopu ice core from the western part of the region shows a decreasing trend in precipitation the converse of the trend in temperature in the eastern part of the region however a rising trend of rainfall has accompanied increasing temperatures as a result of the variable atmospheric circulations from different sources the southwest monsoon the principal controlling factor in the chinese monsoonal temperate glacier region can be classified into the indian monsoon and the bengal monsoon the former passes across the indian peninsula from the arabian sea and transports vapor for precipitation in the western part of the monsoonal temperate glacier region the bengal monsoon originating in the bay of bengal is the major source of precipitation in the eastern part of the region the eastern part is also influenced by the southeast monsoon arriving from the western pacific and the western part is affected in winter by the southern branch of the westerly circulation this complex atmospheric situation results in differing patterns of precipitation in the western and eastern zones although it is clear that both temperature and precipitation affect the glaciers further work is needed to confirm which of these is the major factor influencing present glacier change

peculiar phenomena regarding climatic and glacial variations on the tibetan plateau in contrast to the worldwide intensive warming and consequent glacier shrinkage during the last 30 years two peculiar phenomena have been observed on the tibetan plateau 1 the temperature has decreased about 0 68c on the northern tibetan plateau with smaller than average glacier retreat and meltwater discharge and 2 a number of glaciers have been advancing on the southeast tibetan plateau in response to increased precipitation these observations indicate the complex nature of the response of glaciers to climate changes the main part of the northern tibetan plateau includes the western and central kunlun shan and the northern qiangtang plateau roughly 32 378 n 75 958 e fig 1 the kunlun shan are known as the backbone of asia extending from west to east with wide mountain ranges mostly higher than 6000 m a s l and the highest peak at 7167 m a s l the high and broad mountains and prevailing climate provide favorable conditions for glacier develop ment at present according to the china glacier inventory cgi glaciers in the western and central kunlun shan cover 12 136 km 2 and the equilibrium line altitude ela ranges between 480 and 6200 m there are several isolated mountains in the northern qiangtang plateau with eroded surfaces above 6000 m a s l and some isolated interior lake basins in this region glaciers cover an area of about 1500 km 2 with the ela ranging from 5300 to 6100 m

alteration mineralogy and stable isotope geochemistry of paleoproterozoic basement hosted unconformity type uranium deposits in the athabasca basin canada unconformity type uranium deposits are characterized by mineralization developed along the contact between younger sandstone cover and underlying crystalline basement rocks mineralization may extend up to 400 m into the underlying basement rocks whereas sandstone hosted unconformity type deposits have been well studied deposits hosted primarily in the basement have not this study examines the deposits at rabbit lake dawn lake and mcarthur river in the athabasca basin of canada which are hosted by the metamorphic archean and early paleoproterozoic rocks forming the basement to younger late paleoproterozoic sandstones alteration is similar in the three deposits and is characterized by three distinct paragenetic stages 1 preore alteration involving illitization of plagioclase and amphibole followed by chloritization of biotite and illite which formed at ca 230 c 2 ore stage alteration characterized by uraninite and coarse grained illite which formed at ca 240 c 3 postore alteration comprising spherulitic dravite vein chlorite quartz calcite and fe cu co and pb sulfides which formed at ca 135 c fluid circulation associated with emplacement of later mackenzie dikes initiated partial recrystallization of uraninite a later stage of alteration includes kaolinite and iron hydroxide precipitation formed at much lower temperatures of ca 50 c stable isotope compositions of the alteration minerals in conjunction with their paragenesis indicate that oxidized basinal fluids d 43 to 21 18o 3 8 were derived primarily from evolved seawater and leached uranium from the overlying sandstones of the athabasca formation and transported it into the basement via infiltration along fracture zones associated with reverse faults graphitic units in the basement and preore alteration served as both physical fractured zones and chemical reductants traps for the uranium mineralization the basinal fluids were responsible for the preore illite chlorite synore uraninite illite and the early postore alteration events this differs from many other sandstone hosted deposits where both oxidized basinal and reduced basement derived fluids were responsible for uranium precipitation

proterozoic stratigraphy and tectonic history of the georgetown inlier northeastern queensland the proterozoic sequence in the central part of the georgetown inlier has been divided into the etheridge langlovale croydon and inorunie groups the early to middle proterozoic etheridge group consists of shallow water fine grained clastic metasedimentary rocks and minor basaltic lavas and related dolerite intrusions it was deposited in a uniformly subsiding basin in a continental setting sometime between 2400 and 1570 ma it was first deformed at 1570 ma d1 and again at 1470 ma d2 by major folding events accompanied by low to intermediate pressure metamorphism mainly in the greenschist and amphibolite facies but ranging into the granulite facies in places during d2 the grade of metamorphism increases from west to east extensive s type plutonic magmatism accompanied d2 in the west the langlovale group a fluviatile to marine pro deltaic facies post dates d1 and was deposited before d2 it is moderately folded but not regionally metamorphosed post orogenic magmatism also s type is represented in the western part of the inlier by the subaerial felsic ignimbrite of the croydon volcanic group and related subvolcanic granitoids the volcanic rocks are overlaim by the fluviatile inorunie group which is of uncertain age neither the croydon volcanic group nor the inorunie group is appreciably deformed or metamorphosed in the eastern quarter of the inlier a largely metavolcanic andesitic to felsic sequence may be an allochthonous terrain of early palaeozoic age but it could be proterozoic known proterozoic rocks thought to have been thrust over this sequence crop out on the eastern edge of the inlier they are the halls reward metamorphics and maficultramafic rocks including the boiler gully complex their relationship to the etheridge group is uncertain convective mantle upwelling could account for the extension of the continental crust which allowed deposition of the etheridge group no rifting is apparent and only the sag phase of the model of etheridge et al may be represented underplating of the crust could account for the metamorphism and felsic magma generation during the middle proterozoic the etheridge group shows characteristics of both tectonostratigraphic cycles recognized elsewhere in nothern australia and without better radiometric control correlation is difficult

age budget and dynamics of an active salt extrusion in iran the hormuz salt of kuh e namak iran began rising through its phanerozoic cover in jurassic times and had surfaced by cretaceous times in miocene times the still active zagros folds began to develop and the salt is still extruding to feed a massive topographic dome and two surface flows of salt which have previously been called salt glaciers but are here called namakiers two crude but independent estimates for the rate of salt extrusion and loss are shown to balance the salt budget if the current salt dynamics are assumed to be in steady state first to replace the extrusive salt likely to be lost in solution in the annual rainfall the salt must rise at an average velocity of about 11 cm a second the foliation pattern shows that the extruding and partially dissolved salt column spreads under its own weight the maximum height of the salt dome is consistent with a viscous fluid with a viscosity of 2 6 x 1017 poises extruding from its orifice at a rate of almost 17 cm a k both estimates are consistent in indicating that salt can extrude onto the surface 42 85 times faster than the average long term rate at which salt diapirs rise to the surface the structure fabrics textures and deformation mechanisms of the impure halite all change along the path of the extrusive salt from the dome down the length of both namakiers such changes tend to occur when the flowing salt encounters changes in its boundary conditions and the recognition of buried namakiers is discussed in the light of such observations episodes of salt flow at a rate of 0 5 m per day have been measured along the margin of the n namakier after significant rain showers such brief episodes of rapid flow alternate with long periods when the namakier is dry and stationary the shape of the colour bands cropping out on the n namakier indicate that the flow over the surface of impure salt with a mylonitic texture obeys a power law with n 3 although the reported annual rainfall has the potential of dissolving both namakiers in about 2000 years a superimposed thin marine cover may protect static parts of them for as long as 30 000 to 300 000 years

numerical model to determine the composition of h2o nacl cacl2 fluid inclusions based on microthermometric and microanalytical data natural fluids approximated by the h2o nacl cacl2 system are common in a wide range of geologic environments including sedimentary basins associated with hydrocarbon occurrences and mvt deposits submarine hydrothermal systems and other metamorphic magmatic and hydrothermal environments we present a comprehensive numerical model and microsoft excel based computer program to determine the compositions of fluid inclusions in the h2o nacl cacl2 system based on microthermometric and microanalytical data the model consists of six polynomial correlation equations that describe liquid salinity as a function of nacl cacl2 ratio and melting temperature on each of the ice hydrohalite halite antarcticite cacl2 4h2o and cacl2 2h2o vapor saturated liquidus surfaces the cotectic and peritectic boundaries are determined from the intersections of the liquidus surfaces the model is implicitly internally consistent and topologically correct the model expands upon the compositional range of applicability and the data types that can be used for compositional determination it reproduces experimental data for all compositions that lie within the h2o nacl cacl2 4h2o compositional triangle in the h2o nacl cacl2 system and yields accurate reproductions of the h2o nacl and h2o cacl2 binaries furthermore in comparison to previously published models the one presented here eliminates systematic errors wavy isotherms and cotectic and peritectic curves with local bumps

lithospheric structure beneath the south eastern zagros mountains iran recent slab break off integrated lithospheric modelling based on the combined interpretation of gravity geoid and topography data sets highlights a previously undocumented lithospheric thinning beneath the zagros collisional belt iran which we propose to relate to recent slab break off at the continent ocean transitional lithosphere recent published data on the distribution of seismicity at depth support this interpretation in agreement with other published models for the zagros mountains the overlying crust exhibits by contrast a noticeable thickening reaching a maximum of 52 km the consequent thermal uplift expected from slab break off is suggested to have modified the zagros wedge taper and triggered the recently documented switch from thin skinned to thick skinned deformation in the zagros fold thrust belt

active deformation within the zagros mountains deduced from gps measurements we present and interpret the results of global positioning system gps measurements at 35 stations in and beside the zagros mountain belt sw iran for three campaigns ending march 1998 december 1999 and june 2001 preliminary motion estimates show clearly the change in character along the strike of the belt stations to the se move at 13 22 3 mm a 1 towards n 7 5 e with respect to eurasia most of the shortening indicated by the gps velocities seems to occur in the se zagros along two major seismic zones and along the zagros front to the nw stations move oblique to the trend of the belt towards n 12 8 w at 14 19 3 mm a 1 most of the shortening in the nw zagros seems to occur along the mountain front fault with its major earthquakes as well as along the zagros front the change in direction and magnitude of the velocity vectors across the north south trending kazerun and karebas faults involves extension of up to 4 mm a 1 along the strike of the zagros belt

petrogenesis of the proterozoic athabasca basin northern saskatchewan canada and its relation to diagenesis hydrothermal uranium mineralization and paleohydrogeology abstract in the athabasca basin proterozoic sandstones unconformably overlie archean and aphebian rocks multiple fluid events involving isotopically and chemically distinct fluids which have migrated laterally for considerable distances and along fault zones have produced a paragenetically identifiable assemblage of clay silicate and oxide minerals in the basin and basement rocks altered sandstones and the underlying metasedimentary rocks proximal to fault zones host high grade u ni co unconformity type uranium ore deposits and contain an alteration assemblage of highly crystalline 2m 3t illite 1m kaolinite clinochlore and sudoite hematite dravite and euhedral quartz in the sandstones 18o values of coeval quartz hematite quartz illite quartz dravite illite hematite and kaolinite hematite fluid inclusion temperatures in diagenetic quartz and d values of 1m kaolinite 2m 3t illite dravite and in fluid inclusions in the quartz indicate formation from a basinal fluid that had d values of 60 10 and which underwent salinity temperature and 18o increases from 5 to 34 wt nacl 120 to 240 c and 5 to 3 respectively as a result of increasing burial depth and sustained water rock interactions with the basinal sediments over substantial time periods 18 o 16 o and d h ratios of sudoite and clinochlore in meta sedimentary basement rocks within the alteration haloes indicate formation from a basement derived fluid with 18o and d values of 4 4 and 30 10 respectively that was isotopically distinct from the basinal fluids 18o and d values of late kaolinites in reactivated fault zones indicate formation mainly from low temperature 50 25 c fluids having 18o and d values of 16 and 130 respectively similar to relatively modern meteoric waters in the area some kaolinites have 18o and d values which suggest they formed from meteoric waters at mid latitudes and have experienced varying degrees of oxygen and hydrogen isotope exchange with relatively modern meteoric waters in the re activated faults illite sudoite and dravite have d values that vary by 100 without concurrent changes to their 18o values indicating preferential hydrogen isotope exchange with relatively modern meteoric waters at low temperatures and under conditions of high integrated water rock ratios rb sr isochron and model ages of 1477 57 and 952 ma respectively for the crystalline 2m 3t illites indicate the timing of the high temperature basinal fluid events associated with fluid mixing rb sr and k ar ages on illites with the lowest d values are as young as 300 ma and indicate late stage resetting of their radiogenic isotope systematics as a result of substantial interactions with relatively modern meteoric waters the evolution of sr isotopic compositions of fluids in the basin and basement rocks as reflected by the 87 sr 86 sr ratios of chlorite illite and dravite indicates that mixing of two isotopically distinct fluids in the vicinity of faults was the process by which uranium was precipitated similar to that suggested by oxygen and hydrogen isotope systematics in the clays and silicate minerals nd ratios in the high temperature diagenetic and hydrothermal clay and silicate minerals and the cogenetic uranium ores suggest they all have formed from similar fluids which have interacted substantially with the basin sediments in general the isotopic chemical microthermometric and petrologic data indicate that the athabasca basin has had a protracted fluid history comparable to that documented for more modern sedimentary basins the data clearly show that the major sandstone aquifers have been affected by widespread lateral flow of diagenetic fluids over distances of hundreds of kilometers and also that these fluid migration paths have been modified by cross formational fluid flow near active fault zones

rheology of rocksalt abstract we review progress in experimental determinations of transient and steady state flow properties and processes of natural rocksalt aggregates focusing primarily on results from avery island louisiana domal salt the steady state flow field established from constant stress and constant strain rate tests at temperatures from 50 to 200 c strain rates from 10 5 to 10 9 s 1 and differential stresses from 20 7 to 2 5 mpa has been separated into two flow regimes each fit by a power law relation at the higher stresses and strain rates this relation is e 1 6 10 4 exp 68 1 rt 10 3 5 3 for which the pre exponential constant is expressed in mpa 5 3 s 1 and the apparent activation energy is in j mol 1 creep rates predicted by equation a do not differ appreciably from those predicted previously the relatively low stress low strain rate data are very well fit by e 8 1 10 5 exp 51 6 rt 10 3 2 4 which is comparable conditions predicts creep rates higher and equivalent viscosities lower than does equation a by two orders of magnitude the change in behavior from a to b is ascribed to a change in rate limiting mechanism from cross slip of screw dislocations to the climb of edge dislocations in this dry material subgrain formation dominates microstructural development during steady state flow of salt and from determinations of average subgrain diameters in crystals from 20 different rocksalt bodies flow stress levels between 0 6 and 1 4 mpa have been estimated these values do not bear directly on arguments concerning the nature of forces initiating salt pillow growth because apparently evidence relating to the early deformational history has been overprinted at that stage fluid assisted grain boundary diffusional processes might dominate dislocation creep leading to a linear stress strain rate mechanical response considering buoyancy forces alone behavior described by equation b rather than a reduces the relief necessary to initiate pillow growth but a 1000 fold amplification is required to produce stress differences near 1 mpa that forces other than buoyancy are important is indicated by the occurrence of these same paleostress levels in bedded salts and in shallow offshore concordant intrusions differential loading generally provides the most plausible initial driving force for the growth of diapiric salt structures

the bingham canyon porphyry cu mo au deposit iii zoned copper gold ore deposition by magmatic vapor expansion fluid inclusion microthermometry and laser ablation icpms microanalysis are combined with geological and textural observations to reconstruct the spatial and temporal evolution of magmatic fluids that formed the subvolcanic porphyry cu au mo ore deposit at bingham canyon utah the bingham canyon orebody is exposed over 1 6 km vertically and has the shape of an inverted cup with distinct metal zoning fluid inclusions in the barren but highly veined and potassically altered deep center of the system have intermediate density 0 6 g cm 3 and a salinity of 7 wt percent nacl equiv they have subequal concentrations of na k fe and cu and contain minor co2 the intermediate density fluids were trapped as a single phase mostly at 500 c and 800 bars the au cu rich center near the top of the orebody contains low density vapor inclusions 0 2 g cm 3 coexisting with brine inclusions containing 45 wt percent nacl equiv the vertical transition of different inclusion types indicates phase separation of the single phase input fluid upon volume expansion associated with a pressure drop to 200 100 bars mass balance calculation based on all analyzed inclusion components indicates that the mass of the vapor phase exceeded that of the brine by 9 1 the vapor contained cu as its dominant cation 1 5 wt and contributed about 95 percent of the total amount of copper transported to the base of the orebody bornite chalcopyrite and native gold were precipitated in a narrow temperature interval from 430 to 350 c into secondary pore space created by local redissolution of vein quartz as a result of retrograde quartz solubility in the vapor dominated fluid system intermediate density fluid inclusions in the deepest parts of the peripheral copper ore zone have identical density and composition including similar gold contents as those in the deep center microthermometry and statistical estimation of phase proportions in the inclusions show that the vapor in the peripheral cu rich but au poor ore zone remained denser and the separating brine was less saline 36 wt nacl equiv compared to vapor and brine in the central au cu ore zone this indicates that the peripheral fluids experienced a lower degree of phase separation due to slightly higher fluid pressure at equivalent temperature compared to more strongly expanding fluids in the center of the system the systematic zoning of au cu within the ore shell despite compositionally similar input fluids is interpreted to have resulted from slightly different pressure temperature density evolution paths of magmatic fluids copper was selectively precipitated in the peripheral ore zone in contrast to complete coprecipitation of au and cu in the central upflow zone of the vapor plume the formation of particularly rich cu au ore in the center of the upward expanding fluid plume is consistent with published experimental data showing that the solubility of metals in hydrous vapor decreases sharply with falling pressure due to destabilization of the hydration shell around metal complexes in expanding vapor this interpretation supports the classic vapor plume model for porphyry copper ore formation but additionally emphasizes the role of sulfur bearing complexes as a key chemical control on magmatic hydrothermal metal transport and the deposition of cu and au in porphyry ores our interpretation of selective cu au precipitation as a function of vapor density can explain the more general observation that most gold rich porphyry copper deposits are formed in shallow sub volcanic environments whereas deeper seated porphyry cu mo deposits are generally gold poor

magmatic hydrothermal evolution of highly fractionated granites evidence from the kuiqi miarolite in fujian province se china abstract the kuiqi miarolite a highly evolved alkaline granite pluton is situated in fujian province southeastern china quartz crystals from the kuiqi miarolite contain abundant inclusions which have preserved a complete record of the magmatic hydrothermal evolution five inclusion type were identified i e the melt m type melt fluid ml type daughter mineral bearing s type vapor rich v type and aqueous l type inclusions integrated petrographic microthermometric and laser raman spectroscopy studies demonstrate that the whole magmatic hydrothermal evolution at kuiqi comprises three stages i e the magmatic magmatic hydrothermal and hydrothermal stages the m type inclusions minimal trapping temperatures ca 710 800 c represent the melts entrapped at the magmatic stage of crystallization while the occurrence of euhedral prismatic arfvedsonites in these melt inclusions indicates that the granitic magma was probably volatile rich at the magmatic hydrothermal stage both the ml type inclusions t h ca 500 710 c and coexisting m and v type inclusions reflect the presence of late magmatic fluid circulation and melt volatile immiscibility exhibiting a transition toward the hydrothermal stage at the hydrothermal stage the pressure and temperature 700 485 c drop may have led to oversaturation of the primary saline fluids resulting in the phase separation a highly saline and a volatile rich fluid occurred accompanied by the widespread vapor brine immiscibility the l type inclusions in the miarolitic quartz display bimodal salinity distribution the t h and salinity of the inclusions at the bottom l 1 miarolitic quartz are ca 303 427 c and ca 6 6 17 9 wt nacl equiv respectively while that of the inclusions at the top l 2 are ca 165 232 c and ca 0 2 5 7 wt nacl equiv respectively this indicates a drop of fluid temperature and salinity during the miarolitic cavity formation moreover the low homogenization temperatures and salinities of the l type inclusions suggest an influx of meteoric water during the late hydrothermal evolution stage

metal rich fluid inclusions provide new insights into unconformity related u deposits athabasca basin and basement canada the paleoproterozoic athabasca basin canada hosts numerous giant unconformity related uranium deposits the scope of this study is to establish the pressure temperature and composition p t x conditions of the brines that circulated at the base of the athabasca basin and in its crystalline basement before during and after uo2 deposition these brines are commonly sampled as fluid inclusions in quartz and dolomite cementing veins and breccias associated with alteration and u mineralization microthermometry and laser ablation inductively coupled plasma mass spectrometry la icp ms data from five deposits rabbit lake p patch eagle point millennium and shea creek complement previously published data for the mcarthur river deposit in all of the deposits investigated fluid inclusion salinity is between 25 and 40 wt nacl equiv with compositions displaying a continuum between a nacl rich brine end member cl na ca mg k and a cacl2 rich brine end member cl ca mg na k the cacl2 rich brine has the highest salinity and shows evidence for halite saturation at the time of trapping the continuum of compositions between the nacl rich brine and the cacl2 rich brine end members combined with p t reconstructions suggest anisothermal mixing of the two brines nacl rich brine 180 30 c and 800 400 bars cacl2 rich brine 120 30 c and 600 300 bars that occurred under fluctuating pressure conditions hydrostatic to supra hydrostatic however because the two brines were u bearing and therefore oxidized brine mixing was probably not the driving force for uo2 deposition several scenarios are put forward to account for the cl na ca mg k composition of the brines involving combinations of seawater evaporation halite dissolution mixing with a halite dissolution brine mg ca exchange by dolomitization na ca exchange by albitization of plagioclase na k exchange by albitization of k feldspar and mg loss by mg rich alteration finally the metal concentrations in the nacl rich and cacl2 rich brines are among the highest recorded compared to present day sedimentary formation waters and fluid inclusions from basin hosted base metal deposits up to 600 ppm u 3000 ppm mn 4000 ppm zn 6000 ppm cu 8000 ppm pb and 10 000 ppm fe the cacl2 rich brine carries up to one order of magnitude more metal than the nacl rich brine though the exact origin of major cations and metals of the two brines remains uncertain their contrasting compositions indicate that the two brines had distinct flow paths and fluid rock interactions large scale circulation of the brines in the athabasca basin and basement was therefore a key parameter for metal mobility including u and formation of unconformity related u deposits

ca and mg isotope constraints on the origin of earth s deepest δ13c excursion abstract understanding the extreme carbon isotope excursions found in carbonate rocks of the ediacaran period 635 541 ma where 13 c of marine carbonates 13 c carb reach their minimum 12 for earth history is one of the most vexing problems in precambrian geology known colloquially as the shuram excursion the event has been interpreted by many as a product of a profoundly different ediacaran carbon cycle more recently diagenetic processes have been invoked with the very negative 13 c values of ediacaran carbonates explained via meteoric alteration late stage burial diagenesis or growth of authigenic carbonates in the sediment column thus challenging models which rely upon a dramatically changing redox state of the ediacaran oceans here we present 257 44 40 ca and 131 26 mg measurements along with mg mn and sr data from carbonates of the ediacaran aged wonoka formation fm of south australia to bring new isotope systems to bear on understanding the shuram excursion data from four measured sections spanning the basin reveal stratigraphically coherent trends with variability of 1 5 in 26 mg and 1 2 in 44 40 ca this ca isotope variability dwarfs the 0 2 0 3 change seen coeval with the permian triassic mass extinction the largest recorded in the rock record and is on par with putative changes in the 44 40 ca value of seawater seen over the phanerozoic eon changes in both isotopic systems are too large to explain with changes in the isotopic composition of ca and mg in global seawater given modern budgets and residence times and thus must be products of alternative processes relationships between 44 40 ca and sr and 26 mg and mg are consistent with mineralogical control e g aragonite vs calcite limestone vs dolostone on calcium and magnesium isotope variability the most pristine samples in the wonoka dataset preserving sr concentrations in the 1000s of ppm range and 44 40 ca values inherited from an originally aragonitic polymorph have 13 c carb of 8 to 7 thereby providing strong geochemical evidence that extremely negative 13 c carb values are primary products of the ediacaran surface environment

potash in a salt mushroom at hormoz island hormoz strait iran abstract increasing volumes of potash are currently being discovered in a cluster of diapirs of hormoz formerly hormuz salt near bandar abbas iran most of the potash beds studied so far occur in complex recumbent folds in a salt mountain that would be difficult to exploit safely however holocene marine erosion removed any salt mountains from a sub group of near shore zagros diapirs and exposed their deeper structural levels even though these diapirs are still active their potash deposits are likely more tractable to safe exploitation than in a salt mountain as we make clear here for hormoz island geochemical surveys on hormoz island reveal two separate potash anomalies that are valuable pseudo stratigraphic markers integrating field measurements of the attitudes of bedding with lineaments on air photos suggests that hormoz island consists of a mature bell or plume shaped mushroom diapir with potash beds wound around a toroidal axis of rotation near current exposure levels 2d numerical models simulate the salt mushroom on hormoz island and its internal circulation they also suggest that the diapir has a wide overhand above a narrow stem in this gas rich region we use the mushroom diapir model to outline a regional exploration strategy that has the potential of influencing the world potash market thereafter

insar mapping and modelling of an active iranian salt extrusion abstract interferometric synthetic aperture radar insar imaging is a powerful technique that is increasingly used to extract detailed 3d information on earth surface structures including exposed diapiric surfaces we have used insar to map for the first time the cumulative surface deformation in a 6 km 6 km region surrounding an active salt diapir syahoo and its associated surface salt flow or namakier exposed in the zagros mountains of southern iran images provided by the european space agency were acquired in 12 increments ranging in length between 35 and 1248 days over a 14 year interval between july 1992 and may 2006 the deformation of the salt surface is non steady with extrapolated rates of displacement varying between surficial uplifts of 1 4 mm day 1 511 mm a 1 and subsidence of 2 2 mm day 1 803 mm a 1 growth of a central topographic dome occurs following short wet intervals to create a salt fountain morphology which then slowly decays during the intervening long dry periods salt associated with dynamic bulging9 of the central dome during wet intervals may flow laterally via gravity spreading into the surrounding salt sheet resulting in deflation and subsidence of the dome which is counteracted by growth and inflation of the adjacent namakiers salt bulges9 that migrate down the namakier resulting in local inflationary and deflationary cycles of the surface may be regarded as episodic pulses of gravity spreading areas of inflation and deflation are also observed to commonly reverse during dry to wet periods as the overall salt system effectively self regulates as it continually strives for dynamic equilibrium as long as the source of salt remains undepleted gravity spreading of the dome ultimately results in more buoyancy driven salt flowing up the diapiric neck to replenish and feed the extrusion and maintain the gross fountain morphology

causes of glacier change in the source regions of the yangtze and yellow rivers on the tibetan plateau glaciers are an important element of the environment in the source regions of the yangtze and yellow rivers on the tibetan plateau using geographical information system techniques we have studied changes in the location of glacier margins in two areas the geladandong area in the headwaters of the yangtze and the a nyemaqen shan mountains in the headwaters of the yellow river marginal positions during the little ice age lia maximum in 1969 in the geladandong area in 1966 in the a nyemaqen shan and in 2000 in both areas were determined using aerial photographs satellite images topographical maps and digital elevation models extrapolating the results to the entire source regions of the yangtze and yellow rivers we estimate that the total glacierized area decreased about 1 7 between 1969 and 2000 in the geladandong area and about 17 between 1966 and 2000 in the a nyemaqen shan glaciers were stable or advanced slightly between 1969 and 1995 in the geladandong area and between 1966 and 1981 in the a nyemaqen shan but have retreated since the mid 1990s in the former and since the 1980s in the latter significant increases in summer air temperature and decreases in annual precipitation are the causes of the present retreat as a consequence of the retreat water storage as ice in the yangtze and yellow river drainages is decreasing by 65 70 106 m3 a 1

the origins of the mengye potash deposit in the lanping simao basin yunnan province western china abstract the lanping simao basin lsb is a mesozoic cenozoic continental margin rift basin in western china it formed during the opening and closing of the tethys ocean this basin is also known as a metal belt as it hosts several metal deposits besides the mengye potash deposit however the exact dates of the formation either in the paleocene or the cretaceous and thus the origins of the marine continental or mixed origins of the mengye deposits remain disputed based on the basin s evolution materials of marine origin and or remnant seawater should be present but instead the salt layers of the mengye potash deposit present typically continental lithological features this study examines and reviews evaporative minerals br cl and i cl molar ratios and isotopes of s b and sr i and i cl data for this area has not been previously reported the basin s evaporative minerals are dominated by halite and sylvite the amounts of anhydrite chlorocalcite langbeinite glaserite tachyhydrite and glauberite are small all of these form in both marine and continental environments the values of i and the i cl molar ratios of halite and sylvite are from 0 07 to 0 27 ppm and from 0 03 to 0 11 10 6 respectively dependent on organic substances br and molar br cl values are from 89 08 to 555 45 ppm and from 0 06 10 3 to 0 38 10 3 respectively all of the br cl molar ratios are lower than those of seawater and most of them are 34 s 11 b and 87 sr 86 sr values for evaporative minerals indicate a continental origin for the mengye potash deposit however materials of hydrothermal origin are widely distributed in the basin and may have played an active role for the formation of the potash deposit thus the mengye potash deposit could be of continental origin with a remnant seawater trace

mantle derived gaseous components in ore forming fluids of the xiangshan uranium deposit jiangxi province china evidence from he ar and c isotopes abstract the xiangshan u deposit the largest hydrothermal u deposit in china is hosted in late jurassic felsic volcanic rocks although the u mineralization post dates the volcanics by at least 20 ma the mineralization coincides with intrusion of local mantle derived mafic dykes formed during cretaceous crustal extension in south china ore forming fluids are rich in co 2 and u in the fluid is thought to have been dissolved in the form of uo 2 co 3 2 2 and uo 2 co 3 3 4 complexes this paper provides he and ar isotope data of fluid inclusions in pyrites and c isotope data of calcites associated with u mineralization pitchblende in the xiangshan u deposit he isotopic compositions range between 0 1 and 2 0ra where ra is the 3 he 4 he ratio of air 1 39 10 6 and correlates with 40 ar 36 ar although there is potential for significant 3 he production via 6 li n 3 h 3 he reactions in a u deposit due to abundant neutrons nucleogenic production cannot account for either the 3 he concentration in these fluids nor the correlations between he and ar isotopic compositions it is more likely that the high 3 he 4 he ratios represent trapped mantle derived gases a mantle origin for the volatiles of xiangshan is consistent with the 13 c values of calcites which vary from 3 5 to 7 7 overlapping the range of mantle co 2 the he ar and co 2 characteristics of the ore forming fluids responsible for the deposit are consistent with mixing between 3 he and co 2 rich mantle derived fluids and co 2 poor meteoric fluids these fluids were likely produced during cretaceous extension and dyke intrusion which permitted mantle derived co 2 to migrate upward and remobilize u from the acid volcanic source rocks resulting in the formation of the u deposit subsequent decay of u within the fluid inclusions has reduced the 3 he 4 he ratio and variations in u 3 he result in the range in 3 he 4 he observed with u 3 he ratios in the range 5 17 10 3 likely corresponding to u concentrations in the fluids

the evolution of a porphyry cu au deposit based on la icp ms analysis of fluid inclusions bajo de la alumbrera argentina the chemical and physical evolution of magmatic to hydrothermal processes in the porphyry cu au deposit of bajo de la alumbrera northwestern argentina has been reconstructed with a quantitative fluid inclusion study fluid inclusion petrography microthermometry and single inclusion microanalysis by excimer laser ablation inductively coupled plasma mass spectrometry la icp ms are combined to determine the evolution of pressure temperature and ore metal concentrations including cu and au in the fluids complementary hydrogen and oxygen isotope analyses are used to further constrain the water sources in the evolving system the combined data provide a new level of insight into the mechanisms of metal sourcing and ore mineral precipitation in a porphyry style magmatic hydrothermal system based on previously reported observations of the igneous geology alteration geochemistry and veining history of the subvolcanic porphyries at alumbrera the distribution of fluid inclusion types in space and time is documented six major inclusion types are distinguished the highest temperature brine inclusions up to 750 c p 1 kbar are mainly recorded in barren quartz magnetite veins in the core of the alteration system these polyphase brine inclusions halite sylvite multiple opaque and transparent daughter crystals are interpreted as the most primitive magmatic fluid recorded at the level of the deposit they are of moderately high salinity 50 60 wt nacl equiv dominated by nacl kcl and fecl 2 and contain on average 0 33 wt percent cu and 0 55 ppm au upon cooling and decompression these saline liquids exsolve a vapor phase which is preferentially enriched in cu relative to its main salt components but probably plays a minor role in the formation of this particular deposit because of the inferred small mass fraction of vapor cooling and decompression from the highest initial p t conditions down to about 450 c causes magnetite k silicate alteration but no saturation in au or cu sulfides as recorded by continually high ore metal concentrations in the fluid inclusions coprecipitation of cu and au as chalcopyrite and native gold some early bornite occurs over a narrow range of decreasing fluid temperature with cooling from 400 to 305 c the cu concentration in the brine drops by about one order of magnitude to less than 0 07 wt percent without a proportional decrease in major salt components ore mineral precipitation extracts 85 percent of the cu and au from the fluid it is associated with potassic alteration as shown by a concomitant decrease in the k na ratio of the cooling magmatic brine and by an increase in its ba and sr concentrations elements which are probably liberated in the destruction of calcic igneous minerals the fluid chemical data demonstrate that the metal ratios in this and probably many other porphyry style ore deposits are primarily controlled by the magmatic source of the ore brines on the other hand the final hypogene ore grade of the deposit is controlled by the efficiency of ore mineral precipitation at alumbrera metal extraction is governed by the efficiency of cooling a high flux of magmatic fluid within a small rock volume dilution of residual magmatic fluids as recorded by aqueous fluid inclusions of decreasing salinities and temperatures below 295 c follows after the main stage of copper introduction and is associated with feldspar destructive phyllic alteration geometric relationships fluid analyses and stable isotope data together indicate that phyllic alteration results from postmineralization hydrothermal activity involving minor mixing between meteoric water residual brine and a waning input of magmatic vapor

fluid evolution and uranium mo f mineralization at the maureen deposit queensland australia unconformity related hydrothermal ore formation with a source in the volcanic cover sequence maureen is the largest among several u mo f prospects occurring along a late devonian unconformity in the georgetown area northern queensland australia mineralization is structurally controlled by the intersection of steep east west fractures with an unconformity between a proterozoic basement and a paleozoic cover sequence of continental sedimentary rocks and abundant rhyolitic volcanic rocks the mineralogical composition of high grade ore pitchblende fe rich molybdenite arsenopyrite arsenian pyrite fluorite dickite chlorite goyazite graphite or hematite postlithification brecciation and quartz dissolution indicate a strong chemical gradient and disequilibrium during mineralization between the reduced basement and the largely oxidized cover sequence elemental and mineral zonation centered to faults and fractures cutting the unconformity indicates locally reducing and quartz dissolving conditions during the formation of tabular u mo orebodies which are surrounded by a halo rich in fluorite a detailed petrographic study microthermometry and laser ablation inductively coupled plasma mass spectrometry la icp ms analyses of quartz and fluorite hosted fluid inclusions provide concentrations of ore forming components in fluids related to hydrothermal uranium mineralization three fluids were involved in the mineralizing process at maureen a likely oxidized saline l3 fluid an aqueous l1 fluid and a ch4 bearing carbonic vapor cv the oxidized saline l3 fluids trapped in fluorite and dickite bearing hydrothermal quartz veinlets crosscutting detrital quartz show the highest average concentrations of u 10 47 ppm mo 489 888 ppm and as 318 777 ppm with element ratios close to those of high grade mineralized rocks we suggest that aqueous l1 fluids mixed in the cover sequence with oxidized saline fluids l3 to precipitate fluorite as a distal halo surrounding the east west fractures their mixture an oxidized moderately saline fluid l2 reacted with methane bearing carbonic vapor cv to precipitate u and mo by reduction close to the intersection of the fractures with the unconformity geochemical analysis of coexisting vapor and liquid assemblages indicate mixing of oxidized saline fluids with reduced carbonic vapors to be the driving force for uranium precipitation the maureen deposit shares essential geologic characteristics and hydrothermal processes with proterozoic unconformity related u deposits but probably owes its unusual element association of u with equally redox sensitive mo and abundant f to a source region in the volcano sedimentary cover sequence that was enriched in these elements due to the presence of highly fractionated easily leachable and oxidizable felsic volcanics

holocene marine terraces on two salt diapirs in the persian gulf iran age depositional history and uplift rates slightly inclined holocene marine terraces cover parts of two circular salt diapirs hormoz and namakdan in the persian gulf their relative altitude above present sea level results from a combination of general marine transgression regression affecting the whole area and of local uplift related to salt diapirism differential uplift rate of the studied diapirs in centre to rim profiles was calculated from results based on i radiocarbon ages of skeletal remains of benthic faunas 19 samples which originally grew close to sea level ii original altitude of samples estimated from general sea level oscillation curves for the last 10 kyr and iii present sample altitude measured in the field calculated uplift rates increase from rim to centre on both diapirs in the range from 2 mm yr 1 at the rim to 5 6 mm yr 1 at the interior of hormoz and 1 3 mm yr 1 at the rim to 3 5 mm yr 1 at the interior of namakdan such uplift rate distributions fit into the parabolic profile of newtonian fluid rather than to profiles typical for pseudoplastic fluids the increase in uplift rate with distance from rim to centre of diapirs is gradual as demonstrated also by generally smooth surface of marine terraces no tectonic dissections were found the depositional history on both salt diapirs is similar although they are situated more than 100 km apart marine sedimentation started at about 9 6k cal yr bp on hormoz and at 8 6k cal yr bp on namakdan owing to rapid transgression the sea partially truncated both salt diapirs and rapidly deepened and carbonate mud was deposited on the peripheries of both salt diapirs between 7 and 5k cal yr bp beach deposition replaced carbonate mud soon after 5k cal yr bp the sea retreated from most of the marine terraces on both salt diapirs copyright 2006 john wiley sons ltd

brine rock interaction in the athabasca basement mcarthur river u deposit canada consequences for fluid chemistry and uranium uptake terra nova 22 303 308 2010 abstract the nature of uranium source rocks transport conditions and deposition processes are still highly controversial for world class unconformity related u deposits this article presents the first detailed chemistry of brines associated with the giant mcarthur river u deposit canada la icp ms analysis of individual fluid inclusions suggests mixing between a na ca mg k sr ba brine and a ca mg na k sr ba brine the brines share a common origin evaporated seawater and show evidence for contrasting interaction with basement rocks the na rich brine lost mg and k in alteration haloes around u ores while the ca rich brine results from na ca exchange and sr ba gain u concentrations 0 3 530 g g 1 are anomalously high compared with usual basinal fluids this indicating that u uptake occurred within basement rocks the two brine end members have mixed within the main u deposit area which could be one of the major driving forces for u deposition

cooling pattern and mineralization history of the saint sylvestre and western marche leucogranite pluton french massif central i 40ar 39ar isotopic constraints abstract the saint sylvestre western marche leucogranite complex lc is a composite pluton emplaced 324 m y ago in the variscan continental crust of the northwestern limousin french massif central petrographic structural and new isotopic data are used to constrain the cooling pattern of the pluton in the temperature range for ar retention in muscovite part i and the genetic relationships with the subsequent uranium mineralization postdating the time of intrusion by 40 50 m y part ii a suite of thirty seven muscovite and nine biotite concentrates selected over the entire plutonic complex were analyzed by the 40 ar 39 ar technique muscovite is characterized by well defined plateau ages ranging between 314 and 301 ma while biotite gives less well behaved age spectra with apparent ages varying between 320 and 300 ma the muscovite age variations are systematic and clearly associated with regional trends at the scale of the pluton field petrographic gravimetric and structural relationships indicate that the age pattern is controlled by the intrusion shape and the regional post cooling fault network cutting through the laccolith when restored to their approximate pre faulting geometry the age variations are shown to correlate positively with sample elevation with a top to base difference as large as 10 14 m y over a mean intrusion thickness of 3 km this pattern is interpreted to reflect cooling driven by erosion and exhumation of the thickened variscan crust during the westphalian and is confirmed by two dimensional thermal modelling part ii the data show that 40 ar 39 ar mica ages can postdate the time of crystallization of the host pluton by up to 23 ma depending on the level sampled at the surface they warn against interpreting k ar mica ages from similar low relief igneous settings as closely postdating intrusive events without a precise knowledge of the thermal structure cooling mechanism and post cooling faulting of the pluton in turn provided that the pre faulting geometry of the intrusion is properly assessed the vertical cooling pattern can reveal fine scale variations in the thermal structure of old eroded intrusions that may be extremely useful for recovering quantitative information on the mechanisms and rates of cooling in ancient orogens

pre ore hydrothermal alteration in an unconformity type uranium deposit hydrothermal alteration associated with the formation of unconformity type uranium deposits is manifested mainly by intense chloritic replacement of metamorphic mineral assemblages at the koongarra deposit northern australia three stages of pre ore alteration were identified in chloritized metamorphic muscovite using optical microscopy the electron microprobe and transmission and analytical electron microscopy tem and aem during the first stage metamorphic muscovite was altered to a mica with very low interlayer occupancy k content as low as 0 35 compared to 1 for ideal muscovite high octahedral cation content up to 2 3 whereas ideal muscovite has 2 and high si content high resolution tem images show that these changes in composition were accompanied by frequent layer terminations in contrast to the metamorphic muscovite whereas selected area electron diffraction patterns indicate that the altered muscovite remained a two layer polytype the alteration of muscovite appears more extensive in the outer alteration halo and has been almost completely eradicated in the ore zone where chloritization is more complete during the second stage of the pre ore alteration the altered muscovite was replaced by mg rich serpentine lizardite and clinochlore high resolution tem images show two 10 a mica layers coalescing to one 14 a chlorite layer this type of coalescence appears to involve transformation of one dioctahedral layer of the mica structure to one trioctahedral brucite layer in the chlorite structure through dissolution of the tetrahedral sheets and cation influx in the octahedral site the final stage of the pre ore alteration resulted in replacement of lizardite and clinochlore by fe rich chlorite comparison of the alteration observed in metamorphic muscovite with the alteration observed in metamorphic biotite and garnet shows clearly that chloritization of these phases was also a pre ore alteration event pre ore alteration was principally characterized by the evolution of chlorite from a mg rich phase to an ferich one

the retreat of glaciers in response to recent climate warming in western china glaciers in china are primarily located in the tibetan plateau tp and surrounding high mountains the chinese glacier inventory indicates that there are 46 377 glaciers in western china meteorological records indicate that air temperature in western china has risen by 0 2 c per decade since 1951 and 1998 was the warmest year precipitation in the region increased by 5 10 per decade from 1953 to 1997 using remote sensing and geographic information system methods we have monitored the changes in 5000 glaciers over the past 50 years we conclude that 80 of glaciers in western china have retreated losing 4 5 of their combined areal coverage although some glaciers have advanced in addition regional differences characterize glacier changes over the past few decades for example glaciers in the central and northwestern tp were relatively stable while glaciers in the mountains surrounding the tp experienced extensive wastage mass balance variations for some glaciers show accelerated ice shrinkage in the last two decades

responses of two branches of glacier no 1 to climate change from 1993 to 2005 tianshan china abstract clear understanding of how alpine glaciers respond to climate change is critical to accurately evaluate water resources and to retrieve climate information from the alpine glaciers however different glaciers may have different responses to climate change this study focuses on two branches of glacier no 1 at the head of urumqi river tianshan china these two branches west branch wb and east branch eb have experienced the same pattern of climate warming since their separation in 1993 however these glaciers have responded differently as observed by fieldwork and analysis of their annual mass balances lengths areas equilibrium line altitudes elas to illustrate the different responses of climate change increase in both temperature and precipitation the glacier length response time t rl and climate sensitivity c are calculated for the two branches the length response time and climate sensitivity are 1 89 y and 8 81 for the eb and 1 63 y and 5 92 for wb the different responses are interpreted to be controlled by glacial topographical features with larger slopes and smaller areas making the wb more sensitive to the recent climate warming

geochemistry of the rhyolitic magmas from the streltsovka caldera transbaikalia russia a melt inclusion study the streltsovka caldera located in transbaikalia near the chinese mongolian border represents the largest uranium field associated with volcanics in the world all the rocks volcanics and underlying granites are deeply altered by hydrothermal fluids and their original major and trace element chemistry was strongly modified particularly their primary mobile element concentrations such as fluorine alkalis uranium to determine the primary geochemical characteristics of the magma associated with this giant ore field a study of melt inclusions has been undertaken on the rhyolites many of the melt inclusions are well preserved in quartz phenocrysts from strongly altered rhyolites of the caldera si al fe na k ca f cl mn ti p s and mg were analyzed by electron microprobe u by fission tracks and h u th la ce pr nd sm eu gd dy er yb lu sc ti v sr y nb ba hf by ion microprobe the presence in melt inclusions of daughter minerals such as fluorite f rich mica and ree fluocarbonate and the composition of the silicate melt after homogenization indicate that the streltsovka rhyolites correspond to highly fractionated mildly peralkaline melts 1 04 na k al 1 10 whereas whole rock analyses indicate a peraluminous composition the streltsovka rhyolitic melts are rich in f from 1 4 to 2 7 wt and in u 14 to 23 ppm they are relatively dry with a water content inferior to 2 4 h2o the low cl contents 0 2 cl in melt inclusions of the present study may be related to the mildly peralkaline character of the streltsovka melts nk al 1 04 to 1 10 these melts are rich in ree and present moderate lree fractionation low hree fractionation and a strongly negative eu anomaly the similar ree contents of tulukuevskoe melt inclusions and whole rock indicate that there was no significant fractionation after trapping of the magma on the other hand the glasses from krasny kamen and streltsovskoe rhyolites are richer in hree than the whole rock this agrees with an ree saturation of the magma at the trapping time that is confirmed by the crystallization of parisite as a daughter mineral in melt inclusions melt temperatures obtained from homogenization of the inclusions are relatively high for such magma 1015 30 c and may be overestimated because of a possible volatile loss since the rhyolite formation the lower th 1000 20 c obtained in tulukuevskoe inclusions agrees with their higher f content 2 2 to 3 2 the higher homogenization temperature of krasny kamen inclusions also agrees with the lower f content 0 6 to 0 8

uranium and thorium in the kupferschiefer formation lower zechstein poland the kupferschiefer in poland has an increased u content the facies high in organic matter are significantly enriched in u the maximum values of u are mostly in the lower part of the kupferschiefer sequence the mean x u content in the kupferschiefer from the lubin sieroszowice district is 61 5 ppm and from the rest of the polish zechstein basin is about 26 ppm thorium occurs only in small quantities x 1 5 and 5 ppm respectively the high variance of u and th in the kupferschiefer is due to multistage diagenetic processes the main u carrier is thucholite the investigated thucholite showed a th content below 0 36 ppm thucholite with uraninite exolutions showed small up to 1 0 wt admixtures of u and thucholite without microscopically visible exsolutions up to 37 85 wt u the phosphates showed significant amounts of u up to 0 24 wt the u content in the kupferschiefer is significantly lower than in black shales from other part of the world uranium in the lubin district is not economic

allochthonous salt structure and stratigraphy of the north eastern gulf of mexico ii structure the kinematic evolution of allochthonous salt in the north eastern gulf of mexico proceeds in three stages 1 since its middle jurassic deposition the louann salt was loaded by sediments causing episodic basinward movement of salt ultimately leading to large concentrations of salt masses in a slope environment by the end of the lower cretaceous 2 a regime of starved sedimentation during late cretaceous and early oligocene is responsible for the stabilization of these early salt accumulations 3 with renewed rapid accumulation of sediments during the neogene and pliocene extensive allochthonous salt tongues and sheets formed by gravity spreading within the younger sediments of the slope

model of seawater composition for the phanerozoic we present an inverse model of phanerozoic seawater com position calibrated against updated paleoseawater compositions from fluid inclusions in marine halites the model considers step wise alteration of seawater composition via 1 variable input of river water 2 variable rates of alteration of seawater through reactions at mid ocean ridges and 3 variable rates of alteration of seawater through reactions on ridge flanks and across the ocean floor in general the model achieves agreement with paleoseawater fluid inclusion data for na 1 c a 2 1 s o 4 2 2 and k 1 particularly when variable runoff is considered variable rates of basalt seawater interactions at both ridges and ridge flanks are required to understand the evolution of seawater particularly the observed near constant concentration of k 1 through time

the high grade mo re merlin deposit cloncurry district australia paragenesis and geochronology of hydrothermal alteration and ore formation the merlin deposit located in the cloncurry district mt isa inlier is the world s highest grade mo re deposit although the district is renowned for iron oxide copper gold iocg type mineralization merlin and other mo rich occurrences in the district cannot be classified as iocg type deposits the merlin deposit is hosted by the kuridala group 1690 1650 ma which comprises interbedded phyllite and carbonaceous slate calcsilicate rocks and silicified metasiltstone the mount dore granite part of the williams naraku batholith ca 1540 1490 ma is locally thrust over the metasedimentary rock package an early cu pb zn sulphide stage mount dore deposit mostly overlies with only partial spatial overlap the younger mo re mineralization merlin deposit cu pb zn is mainly hosted by carbonaceous slate as infill of hydrothermal coast supported carbonate breccias the younger mo re mineralization merlin deposit occurs as molybdenite infill of hydrothermal matrix supported breccias along or near the contact between carbonaceous slate and calc silicate rocks and locally cuts the cu pb zn mineralization based on detailed petrography and radiometric age dating u pb zircon and titanite ages re os molybdenite ages we define four main stages of hydrothermal alteration stage 1 represents the earliest hydrothermal stage dated here by u pb titanite geochronology at 1551 12 ma and is characterized by na ca alteration with the formation of hematite dusted albite amphibole carbonates titanite apatite quartz magnetite epidote stage 2 is characterized by the formation of k feldspar tourmaline carbonates quartz apatite and cu pb zn mineralization with chalcopyrite sphalerite pyrite galena stage 3 is dated at 1535 6 ma re os molybdenite and consists of the main mo re event that formed intensely mineralised matrix supported breccias accompanied by k feldspar chlorite alteration stage 4 dated here at 1521 3 ma re os molybdenite is of an age similar to that of the emplacement of the mount dore granite 1517 7 ma u pb zircon and is interpreted as either a remobilization event or a later addition of mo re in veins and disseminations that extends several meters below the mo re breccias with formation of chlorite k feldspar apatite rutile the mount dore granite was thrust above the metasedimentary package at ca 1500 ma which coincided with the waning of the hydrothermal activity in the cloncurry district this event is interpreted to be manifested at the merlin deposit as minor millimeter scale mo re vein formation collectively our data indicate that the merlin and the mount dore mineralization formed via a complex and protracted hydrothermal history that includes a time period ca 1560 1540 that has previously been regarded as unprospective for ore deposit formation in the region

epitaxial salt reefs and mushrooms in the southern dead sea salt usually accumulates in shallow ephemeral brines as simple flat beds however in permanent brines deepening in solar evaporation ponds in the southern dead sea salt accumulation is complicated by the growth of isolated vegetable like salt structures

iron ore deposits associated with hormuz evaporitic series in hormuz and pohl salt diapirs hormuzgan province southern iran abstract three types of iron ore including banded ore hydrothermal metasomatic ore and earthy hematite ochre occur in hormuz and pohl salt diapirs primary banded ores of upper neoproterozoic age contain alternating iron rich and silica rich bands which characterized by the presence of folded hematite rich bands and glacial diamictite fragments of quartz dropstone and other clastics hematite as specularite and oligist is the major mineral in the iron rich bands with minor goethite pyrite magnetite and rare siderite textural relationships between the ore and gangue minerals indicate that these ores are rapitan type sedimentary banded iron deposits this is supported by the geochemical data of iron ores such as low concentration of al2o3 tio2 ba v cr co ni cu and other trace elements plus high value of mno fe v and fe ti ratios and ree patterns subsequent to the formation of iron ore deposits an immense thickness of evaporitic rocks was formed in the oceanic marginal basins negative 13c and 18o values of the cap carbonates and strong positive 34s values of the underlying sulfates are similar to the isotopic patterns of ediacaran rapitan type iron deposits due to salt diapirism in the upper mesozoic and cenozoic eras secondary iron deposits were formed by the activation of hot hydrothermal fluids during salt rising high contents of some indicative elements such as sr zr u th pb zn sn w and mo in the metasomatic iron ores showed that they are the products of iron ore remobilization redeposition in a hydrothermal system the nearness of these ores to the fault zones is consistent with the scheme of migration and redeposition of iron compounds as metasomatic deposits under oxidizing conditions finally earthy ochre was formed following the weathering and erosion of pre existent iron ores

potash in salt extruded at sar pohl diapir southern iran abstract recent progress in the search for potassium salts in iran is outlined after reviewing how most potassium ores form by the evaporation of seawater hydrothermal brines we focus on how most ores are deformed within salt diapirs we summarise the history of the 150 or so diapirs of hormoz salt emergent in the zagros mountains of iran and then consider in detail the nature of potash at sar pohl 60 km west of bandar abbas these deposits are unique in that they occur in salt that extruded sub aerially and spread over the surrounding ground surface via gravity driven collapse mapping and drilling of the complex structural geology of sar pohl found the potash beds to be dispersed in distal salt but concentrated in piles of recumbent folds with axes circumferential to the mountain over lows in the vent rim equivalents of the curtain folds surviving in the stems of german diapirs presumably still exist beneath sar pohl and would be safer to mine than the recumbent folds in this soluble mountain however it should be possible to continuously pump water onto the exposed salt and guide the resulting brines through evaporation ponds and then a crystallization plant on the adjacent plains this approach would accelerate natural degradation processes but harvest potash currently draining into the gulf

quantitative evaluation of the transporting capacity of unconformities a case study from the zhongguai area junggar basin nw china abstract unconformities are special geologic bodies with a three layer structure including the rock above the unconformity a weathered clay layer and a leached rock the upper wuerhe upper permian bottom unconformity in northwest junggar basin is the main pathway system linking the zhongguai zg lift with hydrocarbon source kitchens based on the log response characteristics of the unconformity s vertical structure and core calibration a principal component analysis pca was applied to extract and identify the evaluation parameters of the unconformity s vertical structure on the basis of darcy s law the quantitative characterization formula of the unconformity s transport capacity with an actual geological significance was established after taking several factors into consideration the migration probability of the unconformity was used to evaluate the possibility that the unconformity acted as a migration pathway consequently a relationship between the migration probability and the evaluation parameters was developed to analyze the effectiveness of these parameters in characterizing the transporting capacity of the unconformity this study shows that the quotient of the two principal components extracted from the conventional logging curves pc1 pc2 have different reference values in the leached and parent rocks the distribution of thicknesses of the weathered clay layer and the leached rock is well matched with the distribution of paleogeomorphology the parameters representing only a single geological factor are not enough to determine whether the unconformity acted as a migration pathway the flow coefficient cf containing multiple factors can effectively and clearly identify the transporting capacity of the unconformity considering the positive correlation between the parameter cf and the migration probability of the unconformity the oil and gas shows of the area with a parameter cf greater than 10 10 4 cm2 s are abundant which is the superior transporting area of the unconformity and there is a good matching relationship between the distribution of the superior transporting area of the unconformity and that of the hydrocarbon distribution

uranium metallogenesis in south china and its relationship to crustal extension during the cretaceous to tertiary south china is rich in vein type hydrothermal uranium deposits hosted in granitic volcanic and carbonaceous and siliceous pelitic sedimentary rocks the uranium deposits are spatially associated with extensional structures and or mantle derived mafic dikes both the uranium deposits and mafic dikes are cretaceous to tertiary in age temporally coincident with the crustal extension carbon isotope analyses of calcite deposited in the main stage mineralization in the veins from 12 representative uranium deposits yield 13c values of ore forming fluids mainly from 4 to 8 per mil which are permissive of a mantle origin for the co2 in the ore forming fluids a mantle origin is consistent with the association of the deposits with mafic dikes and the 3he 4he ratios of ore forming fluids e g 0 10 2 02 ra for the volcanic hosted xiangshan uranium deposit isotopic compositions of h and o demonstrate that water in the ore forming fluids is predominantly meteoric in origin ore forming temperatures ranged approximately from 150 to 250 c uranium rich crustal rocks in south china may have been the sources for the uranium crustal extension and associated mafic magmatism are considered to have heated the rocks and allowed co2 possibly from mantle sources to migrate upward and to mix with co2 poor meteoric water the co2 rich hydrothermal fluids mobilized uranium from the source rocks and then the uranium was deposited in various host rocks to form the uranium deposits

observed changes of cryosphere in china over the second half of the 20th century an overview during approximately the past five decades changes in snow cover mountain glaciers frozen ground including permafrost sea ice and river ice have been observed in china however most data were published in chinese and thus unknown to the international communities here we review these published results to show an overview of cryospheric changes in china for the last 50 years long term variability of snow cover over the qinghai xizang tibetan plateau qxp is characterized by large interannual variability superimposed on a continuously increasing trend glacier changes in western china vary remarkably in different regions although in most mountains the glaciers display a retreating trend 80 or have even vanished some glaciers 20 are still advancing frozen ground including permafrost has experienced a rapid decay since the 1980s and these changes are occurring both in the qxp and in the cold regions of north china sea ice areas in the bohai and north yellow seas have been shrinking since the 1970s interannual variations possibly relate to the solar cyles and sea ice extent extremes relate to el nino southern oscillation enso events the freeze up and break up dates of river ice in north china in the 1990s are on average 1 6 days later and 1 3 days earlier respectively than the 1950s 1990 mean frozen duration and the maximum thickness of river ice are respectively 4 10 days shorter and 0 06 0 21 cm thinner in the 1990s than the average cryosphere the cryosphere in china is mainly located in the qinghai xizang tibetan plateau hereafter qxp the eastern tien shan the altai shan the east pamirs and northeast china the total number of glaciers in china is 46 298 with a total area of 59 406 km 2 and an ice volume of 5590 km 3 the permafrost and the seasonally frozen ground sfg cover an area of 1 49 10 6 and 5 28 10 6 km 2 accounting for 11 5 and 55 of chinese land territory respectively the snow covered area in china is around 9 0 10 6 km 2 and of this an area over 4 8 10 6 km 2 consists of unstable snow cover duration 60 days is mainly located in the qxp north xinjiang including the tien shan and the inner mongolia northeast china hereafter im nec regions the mean snow cover areas of these three regions are 2 3 10 6 0 5 10 6 and 1 4 10 6 km 2 respectively seasonal sea ice forms in the bohai sea and in the northern yellow sea of china sea ice forms in mid to late november reaches its

calcite twinning constraints on late neogene stress patterns and deformation mechanisms in the active zagros collision belt mechanically induced calcite twins in veins and host rocks of late cretaceous to miocene age in iran have been used to determine regional arabia eurasia collisional stresses a late folding stress regime with a compression oriented 025 15 has been identified across the zagros belt and the southern iranian plateau this late neogene stress pattern agrees with the current stress field determined from the focal mechanisms of basement earthquakes and suggests that the hormuz salt decollement poorly decouples the basement and cover stress fields our data show that the collisional state of stress has been relatively constant since ca 5 ma the magnitudes of the stresses obtained from the twinning analysis are unexpectedly low and to a first approximation they are constant across the zagros simply folded belt this result supports an overall mechanism of buckling of the detached zagros cover internal viscous plastic processes help to relieve stress within this cover thus lowering its seismogenic potential beyond these regional implications this study underlines the potential of paleostress analyses in constraining both the tectonics and the mechanics of ancient and active foreland fold belts

viscosity estimates of salt in the hormuz and namakdan salt diapirs persian gulf the parabolic surface profiles of the hormuz and namakdan salt diapirs in the persian gulf suggest that they have been extruding with newtonian viscous rheologies for the last 10 4 years we derive velocity profiles for these diapirs neglecting gravitational spreading and erosion dissolution while assuming incompressible newtonian rheology of the salt fitting known rates of extrusion at specific points in its elliptical cross section the dynamic viscosity of the salt of the hormuz diapir is found to range between 10 18 and 10 21 pa s approximating its sub circular cross section to a perfect circle the range of viscosity of the salt of the namakdan diapir is obtained as 10 17 10 21 pa s these calculated viscosities fall within the range for naturally flowing salts elsewhere and for other salt diapirs but are broader than those for salts with newtonian rheology deforming at room temperatures the salts of the hormuz and namakdan diapirs are expected to exhibit a broader range of grain size which matches the limited existing data

allochthonous salt structure and stratigraphy of the north eastern gulf of mexico part ii structure abstract the kinematic evolution of allochthonous salt in the north eastern gulf of mexico proceeds in three stages 1 since its middle jurassic deposition the louann salt was loaded by sediments causing episodic basinward movement of salt ultimately leading to large concentrations of salt masses in a slope environment by the end of the lower cretaceous 2 a regime of starved sedimentation during late cretaceous and early oligocene is responsible for the stabilization of these early salt accumulations 3 with renewed rapid accumulation of sediments during the neogene and pliocene extensive allochthonous salt tongues and sheets formed by gravity spreading within the younger sediments of the slope autochthonous salt allochthonous salt and detached allochthonous salt are typical stages of evolution major down to the basin growth faults separate allochthonous salt sheets from their original feeder stocks extension along down to the basin master growth faults is compensated mainly by salt withdrawal and partly by basinward shortening

hydrothermal alteration of monazite in the precambrian crystalline basement of the athabasca basin saskatchewan canada implications for the formation of unconformity related uranium deposits microanalytical studies of basement rocks below the athabasca sandstone basin indicate that monazite is the dominant uranium bearing mineral in the study area drill core samples of hydrothermally altered basement show that monazite is commonly altered to a th silicate phase and uranium has been significantly mobilized on average 75 of the uranium bound to monazite is leached out during monazite alteration in contrast no substantial mobilization of uranium from detrital minerals e g zircon has yet been observed in the athabasca sandstones it is suggested that hydrothermal alteration of granitic rocks especially potassic pegmatoids and potassic orthogneisses of the sub athabasca basement represents the most important uranium source for the unconformity type deposits

on the mineralogy of the anthropocene epoch the anthropocene epoch has been proposed as a new post holocene geological time interval a period characterized by the pervasive impact of human activities on the geological record prior to the influence of human technologies the diversity and distribution of minerals at or near earth s surface arose through physical chemical and or biological processes since the advent of human mining and manufacturing particularly since the industrial revolution of the mid eighteenth century mineral like compounds have experienced a punctuation event in diversity and distribution owing to the pervasive impact of human activities we catalog 208 mineral species approved by the international mineralogical association that occur principally or exclusively as a consequence of human processes at least three types of human activities have affected the diversity and distribution of minerals and mineral like compounds in ways that might be reflected in the worldwide stratigraphic record the most obvious influence is the widespread occurrence of synthetic mineral like compounds some of which are manufactured directly for applications e g yag crystals for lasers portland cement and others that arise indirectly e g alteration of mine tunnel walls weathering products of mine dumps and slag a second human influence on the distribution of earth s near surface minerals relates to large scale movements of rocks and sediments sites where large volumes of rocks and minerals have been removed finally humans have become relentlessly efficient in redistributing select natural minerals such as gemstones and fine mineral specimens across the globe all three influences are likely to be preserved as distinctive stratigraphic markers far into the future

geology and models of salt extrusion at qum kuh central iran profiles through the summit of a small nearly axisymmetric extrusion of oligocene and miocene salt and simple analogue models of it simulate the profiles of piles of ductile nappes extruded from convergent orogens the salt extrudes from a reactive diapir along a major strike slip fault at about 82 mm a 1 and rises 315 m above the central plateau of iran the salt has the distinctive smooth profile of a viscous fountain in which an asymmetric apron of allochthonous salt gravity spreads over its surroundings from a summit dome curtain folds developed in the source layer extrude from the diapir and are refolded by major recumbent folds with circumferential axes that simulate nappes minor flow folds with circumferential axes refold major folds in the top 10 50 m of surficial salt master joints 100 m long indicate brittle failure of dilated salt by regional stress fields tuned to the dimensions of qum kuh analytical and analogue models of viscous extrusions constrain the dynamic salt budget and a time of extrusion of at least 42 000 years new analogue models suggest that the number amplitude and spacing of major recumbent folds within the extruded salt and ductile nappe piles record the number amount and relative timing of fluctuations in the driving forces

coupled fluid flow heat and mass transport and erosion in the alberta basin implications for the origin of the athabasca oil sands regional topography driven flow systems related to laramide tectonic rebound were simulated using two dimensional coupled fluid flow heat transport and solute transport numerical models to replicate present formation water salinity and temperature distributions and investigate the accumulation of the athabasca oil sands previous modelling of this system was replicated and it predicted repeated replacement of all basin formation water with freshwater during deposition of the oil sands due to high permeabilities to match present alberta basin temperature and salinity distributions model hydrostratigraphy permeabilities and heat fluxes were adjusted this revised model conducts fluids along the mannville aquifer rather than the upper devonian aquifer and replicates present salinity distributions assuming instantaneous uplift around 60 ma fluid fluxes in principal aquifers decrease by two orders of magnitude using new permeabilities resulting in primarily conductive heat transport thus genesis

geology of the nabarlek uranium deposit northern territory australia the nabarlek deposit is an unusually high grade uranium orebody 1 84 u 3 o 8 12 000 metric tons hosted by amphibolite and semipelitic schist of lower proterozoic age it is unusual in the alligator rivers uranium field in being hosted by amphibolite the disposition of the ore is controlled by a prominent reverse fault which is part of a larger zone of reverse faulting the fault zone is nearly perpendicular to prominent metamorphic s 2 and s 3 fabrics a geometry which might enhance the fluid rock ratio a striking feature of the deposit is the extent and intensity of hydrothermal alteration which extends more than 1 km from the ore alteration remote from the ore resulted in pseudomorphous replacement of metamorphic biotite amphibole and feldspar under conditions of a low fluid rock ratio and mass transfer ore is associated with a small desilicification zone within and superimposed on this larger envelope the fluid rock ratio and mass transfer resulting mainly in silica loss were high within this interior zone and produced intense pervasive alteration leading to an assemblage of phengitic white mica magnesian chlorite and hematite large volumes of fluid were required to effect the massive desilicification and deposit such a volume of uranium given the current knowledge of the solubility of quartz and uraninite ore deposition predominantly as uraninite postdated intense phengitic white mica alteration chlorite however is the main gangue mineral possibly reflecting a change in redox conditions accompanying ore deposition a redox control on ore deposition is supported by the sparse ocurrence of host rock graphite which evidently participated in ch 4 forming reactions abundant hematite in the alteration halo suggests the presence of an oxidized fluid log f sub o 2 approx 35 at 200 degrees c which was thus suitable for transporting ore forming quantities of uranium probably as chloride complexes primary mineralization underwent incongruent dissolution to coffinite in equilibrium with a vanadian illite kaolinite and secondary hematite assemblage residual ore weathering of primary and residual ore produced yellow and green secondary uranium minerals both pseudomorphous after earlier ore types and as crusting of open goethite lined fractures

progressive unconformities within an evolving foreland fold thrust belt zagros mountains a major angular unconformity between the bakhtyari conglomerates and the underlying agha jari formation has long been interpreted as indicating that orogeny in the zagros simply folded zone took place in plio pleistocene times this study uses field evidence of unconformities between older units in conjunction with geological maps and cross sections to argue that the front of the zagros simply folded zone has propagated in time and space these unconformities indicate that deformation started as early as end eocene in the northeast of the simply folded zone and propagated progressively to the southwest where unconformable contacts are only seen between younger units as shortening continued the southwest migration of the deformation front drove the foreland basin in front of it to its present position along the persian gulf and mesopotamia the climax of orogeny took place at end pliocene time when the most extensive unconformity in the zagros simply folded zone developed between the upper bakhtyari formation and older units active seismicity and documented present uplift imply that the simply folded zone is still propagating southwestward

accurate and precise quantification of major and trace element compositions of calcic sodic fluid inclusions by combined microthermometry and la icpms analysis abstract determination of absolute trace element concentrations in fluid inclusions using laser ablation la icpms requires an internal standard i e the concentration of one element must be independently known from independent observation microthermometric determination of the last melting temperature of ice hydrohalite or halite is routinely used to calculate apparent salinities in wt nacl equivalent using phase relations in the binary h 2 o nacl system to estimate na concentration calculating the concentrations of all other elements requires an empirical correction if additional salt concentrations are of similar magnitude as that of nacl if cacl 2 is the main additional salt component as in many low temperature basin and basement brines absolute na concentrations wt nacl abs can be obtained by observing two melting temperatures hydrohalite and either ice or halite uniquely defining the major element composition of the fluid in the ternary model system h 2 o nacl cacl 2 and allowing na to be used as internal standard for quantifying all minor and trace elements test results for a range of compositions show that calcium concentration can be determined more precisely by microthermometry than by la icpms analysis but that both methods agree within error the combined approach of microthermometry and la icpms analysis described here permits reliable quantification of major ca na as well as trace element concentrations in sodic calcic brine inclusions even in ca rich host minerals such as fluorite or ca bearing carbonates

fluid inclusion evidence on the origin of some australian unconformity related uranium deposits fluid inclusions in altered and unaltered host rocks and hydrothermal quartz calcite and dolomite from the unconformity related uranium deposits of koongarra nabarlek and jabiluka northern territory australia were examined using standard microthermometry laser raman microprobe and scanning electron microscopy decrepitated gases were analyzed in a mass spectrometer the relationship of fluid inclusions to alteration and mineralization was established by occurrence restricted to the alteration zones around the deposits and the presence in fluid inclusions of solid phases which also occur as megascopic phases in the alteration secondary halite saturated fluid inclusions in altered host rock quartz and in early hydrothermal quartz veins are believed to relate to hydrothermal alteration associated with ore deposition these inclusions are identical to primary inclusions in silicified and boron metasomatized kombolgie formation sandstone above the jabiluka 2 deposit durak et al 1983 and hence sample post kombolgie fluids the trapped fluid is saline and calcium rich ca 23 equiv wt cacl 2 and sulfate poor so super 2 4 0 001 m no gases were detected in the vapor phase of such inclusions and the median vapor disappearance temperature is 140 degrees c primary inclusions in postore dolomite veins and secondary inclusions in host rock and hydrothermal quartz sample postore hydrothermal fluid this fluid is hypersaline and also calcium rich typically 35 equiv wt cacl 2 and is saturated with as many as 11 solid phases including dolomite and iron rich chlorite vapor bubbles in these inclusions contain methane and minor n 2 and the median vapor disappearance temperature is 127 degrees c aromatic hydrocarbons detected by mass spectrometry are possibly related to this population the calcic brines are thought to have been terrestrial in origin and derived from the oxidized red bed sediments overlying the deposits macarthur basin ore deposition was a response either to reduction of the ore bearing fluid by direct interaction with graphite and ferrous iron in the wall rocks or by mixing with a methane and higher hydrocarbon bearing brine represented by postore fluid inclusions ore deposition and related hydrothermal alteration occurred between 200 degrees and 300 degrees c under a depth of cover of ca 2 km this temperature is consistent with independent temperature constraints and suggests an anomalous thermal gradient during ore formation

genesis of coffinite and the u ti association in lower old red sandstone sediments ousdale caithness scotland the mineralogy of a fault related uranium occurrence in clastic rocks overlying granite is described from borehole material coffinite is the only important uranium mineral other notable minerals are sulphides fluorite calcite and hydrocarbon coffinite is epigenetic and paragenetically late rimming sulphides and hycrocarbon it occurs partly in spatial association with a tio2 mineral probably anatase this u ti association is attributed to adsorption of u by altered ti minerals prior to growth of the u mineral thus is has similarities with many diagenetic occurrences though their mineralogy is usually different the u ti association being represented by uranotitanates the latter are attributed to local supersaturation of tio2 which did not occur at ousdale because ti was relatively mobile in the fluids coffinite tio2 quartz is interpreted as a stable low temperature assemblage the mineralogy thus indicates a hydrothermal uranium mineralization of an unusual type without prominent uraninte formed from relatively low temperature fluids containing complexing agents which mobilized ti

volcanogenic uranium mineralizations in the sierra pena blanca district chihuahua mexico three genetic models the sierra pena bianca district is a good example of uranium deposits related to volcanic rocks which are here considered to be both the source of the uranium and the host rocks for its deposition the mineralization occurs mainly in the lower units of a cenozoic volcanic pile the nopal and escuadra rhyolites that overlie a mesozoic calcareous basement three genetic types of mineralization have been identified 1 a hydrothermal type illustrated by the nopal 1 deposit the primary mineralization relics of a pitchblende pyrite association are observed and the associated kaolinization of the rock are related to the circulation of hydrothermal fluids in breccias and fault systems the present day mineralization consists of mainly u super 6 minerals uranophane weeksite etc produced during later stages under oxidized conditions 2 a mixed supergene exhalative type exemplified by the las margaritas deposit the u mo minerals precipitated due to the mixing of oxidized u enriched ground waters with reduced h 2 s rich fluids in a tectonic valley 3 a supergene type reflected by the puerto 3 deposit the u super 6 mineralization uranophane is located between two impermeable layers and has a roll shape the precipitation of this u super 6 silicate with kaolinite and quartz is due to an sio 2 enrichment of the solutions at low temperature

glacier changes during the past century in the gangrigabu mountains southeast qinghai xizang tibetan plateau china the present research focuses on glacier changes in the southeast of the qinghai xizang tibetan plateau where most of the temperate glaciers in china are located our results show that the 102 measured glaciers in the region have all retreated between 1915 and 1980 with total area and volume decreases of 47 9 km 2 and 6 95 km 3 respectively the extrapolated mass loss of all glaciers in the gangrigabu mountains amounted to 27 km 3 9 8 of the ice mass in 1915 between 1980 and 2001 glaciers in the region have also experienced a general retreat however up to 40 of the glaciers were advancing our analysis demonstrates that precipitation in the studied area has increased substantially since the mid 1980s this precipitation increase is likely to bring about a positive mass balance for glaciers in the region so that the retreat of retreating glaciers might slow down or even turn into advance considering the sensitivity of the temperate glaciers in the region and the uncertainty in climate projections more attention must be paid to glacier changes in the southeast tibetan plateau region

evolution of devonian alluvial systems in an oblique slip mobile zone an example from the broken river province northeastern australia abstract the lower 1500 m of the late devonian bulgeri formation was deposited in a tectonically active foreland basin in response to a major late devonian orogeny in the broken river province northeastern australia the basin was bounded to the east by an uplifted belt of palaeozoic sedimentary and volcanic rocks that was deformed east of an active thrust zone gray creek fault to the south the basin was bounded by igneous and metamorphic basement rocks uplifted along a major oblique slip fault zone clarke river fault facies analysis and mapping of alluvial stratigraphy has resulted in the recognition of compositionally distinct coalescing axial and transverse alluvial drainage systems the axial drainage system flowed to the northeast approximately parallel to the gray creek fault and away from the clarke river fault the system drained the cratonic basement to the south and west and accumulated mainly feldspathic and quartzose sediments a lower fine grained succession and an upper coarse grained succession are recognised the lower succession rockfields alluvial system was deposited in broad sandy low sinuosity channels and semi permanent floodplain lakes these rivers drained ultimately northward into a retreating coastal plain and shallow sea that lay over the georgetown province the upper succession bulgeri alluvial system was deposited in gravelly and sandy braided rivers emanating from south of the clarke river fault the transverse distributary system stopem blockem alluvial system accumulated mainly lithic coarse grained sediments deposited in gravelly braided rivers sourced from the uplifted orogenic belt to the east these rivers flowed towards the northwest before coalescing with the axial drainage system where they changed to a northerly orientation uplifted fault blocks of devonian limestone within the basin locally contributed limestone gravel to these rivers between the coalescing axial and transverse river systems lay extensive floodplains which received a slow but compositionally mixed supply of mainly fine grained sediments long periods of weathering resulted in the development of reddened palaeosols with well developed calcrete horizons the palaeogeography and fluvial style of the lower bulgeri formation is compared to the gulf of carpentaria in northeastern australia analysis of the architecture of these alluvial systems has led to recognition of at least three subsidence driven tectonic cyclothems and this is supported by simple quantitative modelling the lower part of each cycle begins with a thin conglomeratic succession above an unconformity and is overlain by thick relatively fine grained syn tectonic alluvial facies deposited during maximum subsidence the upper part of each cycle is marked by increasingly coarse grained post tectonic alluvial facies these were deposited by gravel progradation following cessation of uplift or thrusting in the source areas and concomitant slowing of subsidence rates

transport of rare earth elements by hydrocarbon bearing brines implications for ore deposition and the use of rees as fluid source tracers abstract low temperature 100 160 c hydrocarbon bearing brines mobilize ree at concentrations up to several thousand ppm total rare earth elements ree at el hammam morocco the major element chemistry na ca mg and temperature of the fluids in this system are consistent with those of oil field brines in contrast ree concentrations in the fluid suggest a significant element input from a magmatic source spatially related lamprophyres predating the formation of el hammam share a similar trace element signature therefore hydrocarbon bearing basinal brines seem to have leached some of these elements through fluid rock interaction from the lamprophyres supporting the ability of oil field brines to mobilize not only base metals as in mississippi valley type mvt deposits but also rare earth elements the stability constants of ree aqueous complex at temperatures of 100 160 c the chemistry of oil field brines worldwide and the partitioning behavior of ree between fluorite and water at el hammam indicate that acetate carbonate and fluoride are likely to be major contributors to ree mobilization in these settings the direct implications of the low temperature transport of ree by oil bearing brines is that in systems where these kind of fluids occur the ree signature observed may not reflect the source of the fluid as much as a combination of fluid source and fluid rock interaction in addition oil field brines can efficiently scavenge transport and deposit ree leading to anomalously high accumulations such as the el hammam fluorite deposit and may also contribute to ree mobilization and concentration in other systems

numerical simulation of the flow velocity and temperature of the dongkemadi glacier the flow velocity and ice temperature of a glacier reflect the response of the glacier to climate change however because of the restrictions of observation conditions it is often difficult to acquire the ice velocity and temperature field for the entire glacier profile in this study we use a two dimensional ice flow model and energy balance model to simulate the ice velocity and temperature using field measurements made with ground penetrating radar for the profile of the small dongkemadi glacier and verify the simulated surface velocity with interferometric synthetic aperture radar data the simulation for the flow velocity shows that the velocity depends on the surface and bedrock slopes glacier profile shape and mass supply way and the surface velocity increases with an increase in the surface slope sensitivity analysis shows that the terrain and slope affect the profile velocity simulation results for temperature show that the ice body temperature is highest in the lower ice body at a subglacial position altitude of 5520 m a s l this location not only gathers melt water most easily but also undergoes the strongest effect of geothermal heat flow the distributions of the ice velocity and ice body temperature provide a good reference for research on glacier vulnerability assessment and the response of glaciers to climate change

signature and hydrologic consequences of climate change within the upper middle brahmaputra basin a prevailing perception is that the glaciers and perennial snow and ice covered areas scap or in the himalayan region are fast contracting however systematic studies providing the quantitative estimates of scap as a function of time within individual river basins are lacking the importance of meltwater in river flows varies greatly from one river basin to another yet the actual estimates of those contributions are largely unknown this study bridges such knowledge gaps for the upper middle brahmaputra basin by using best available digital cartographic and remotely sensed snow cover data we find that when the entire basin is considered scap decreased from 7637 764 in 1980 to 4298 1422 km2 in 1992 however it has increased to 7160 2248 km2 in 2000 from 2000 to 2010 the scap has remained nearly constant around a mean of 10 052 1468 km2 the same trend is observed within individual physiographic zones of the basin such increase in scap is due to the increase in the precipitation over the middle brahmaputra basin and the nyainquentanglha mountains as observed in station records the incursion of moist air through the brahmaputra valley to the higher elevations within the nyainquentanglha mountains causes snowfall during pre monsoonal and post monsoonal seasons and an expansion of the scap glacial expansions in the nyainquentanglha mountains have also been observed in other recent studies in addition to the increase in precipitation and scap another manifestation of climate change observed in this basin is the increasing temperature with a mean annual trend of 0 28 c decade the hydrologic consequences of the observed effects of climate change are expected to be an insignificant change in streamflows in the watersheds drained by the upper brahmaputra river but a perceptible increase in river discharges in the watersheds drained by the middle brahmaputra river and its tributaries particularly within the upper and lower catchments of the middle brahmaputra basin copyright 2012 john wiley sons ltd

metallogeny of the zoujiashan uranium deposit in the mesozoic xiangshan volcanic intrusive complex southeast china insights from chemical compositions of hydrothermal apatite and metal elements of individual fluid inclusions abstract the zoujiashan u deposit in the mesozoic xiangshan volcanic intrusive complex is one of the largest volcanic related type u deposits in china chemical composition of hydrothermal apatite and metal contents in individual fluid inclusions of quartz and fluorite are investigated in order to understand the precipitation mechanism of u and to further constrain the origin of u and ore forming fluids of the zoujiashan deposit illitization hematitization and u mineralization successively occurred within rhyolite and porphyritic lava three types of hydrothermal apatite are identified apatite type 1 ap1 and apatite type 2 ap2 are both euhedral subhedral crystals found in hematitization zone while only ap2 shows evident irregular chemical zoning along its rims apatite type 3 ap3 occurs as anhedral aggregates closely associated with u minerals in u ore veins implying synchronous precipitation of ap3 and u ores comparable chemical compositions of ap1 and cores of ap2 including similar high cl content indicate both of them were precipitated from a cl rich fluid that induced hematitization the elevated f contents of ap3 and rims of ap2 implies that a f rich fluid was involved and altered ap2 during the main stage of u deposition ap1 and cores of ap2 have lower mn contents than ap3 and rims of ap2 indicating an oxidized character for the cl rich fluid and a reducing character for the f rich fluid metal contents of fluid inclusions in fluorite and quartz occurring in u ores suggest that two end members of fluids including a u rich and a u poor were involved in the main stage of u mineralization mixing between these two fluids led to the deposition of u and th minerals through oxidation reduction reactions and destabilization of th f complexes respectively the u rich fluid is depleted in th and sr compared with the u poor fluid based on comparison of chemical compositions of apatite and fluid inclusions we suggest that the cl rich fluid precipitating ap1 and ap2 corresponds to the u rich end member fluid while the f rich fluid precipitating ap3 represents a mixture between the two end members the high u 12 7 58 5 ppm in the u rich end member fluid is in agreement with a relatively high oxygen fugacity and a surface derived origin the u poor end member fluid has lower rb cs than the u rich end member and the unaltered host rocks indicating the u poor fluid was derived from a mantle wedge that experienced addition of cs by fluids generated from the devolatilization of the subducted paleo pacific slab