space geodetic tools provide early warnings for earthquakes and volcanic eruptions development of space geodetic techniques such as global navigation satellite system and synthetic aperture radar in last few decades allows us to monitor deformation of earth s surface in unprecedented spatial and temporal resolution these observations combined with fast data transmission and quick data processing enable us to quickly detect and locate earthquakes and volcanic eruptions and assess potential hazards such as strong earthquake shaking tsunamis and volcanic eruptions these techniques thus are key parts of early warning systems help identify some hazards before a cataclysmic event and improve the response to the consequent damage

assessment of crystallographic orientation effects on secondary ion mass spectrometry sims analysis of cassiterite abstract crystallographic orientation effects on ion microprobe analyses for u pb and o isotopes have been reported for a number of oxide minerals including rutile tio2 and baddeleyite zro2 here we evaluate the effects of crystal orientation on u pb and o isotopic data measured by ion microprobe on cassiterite sno2 which is isostructural with rutile the crystallographic orientations of mounted and polished grains of cassiterite were determined by electron backscatter diffraction ebsd those grains were then analysed for u th pb isotopes and 18o 16o compositions using the shrimp rg and shrimp si ion microprobes respectively based on these data cassiterite appears to show no dependence of key measurement parameters such as uo2 uo pb uo or 18o 16o ratios at the achieved precision with crystallographic orientation the contrasting behaviour of isostructural cassiterite and rutile provides new insights into the mechanisms leading to crystallographic orientation effects during ion microprobe analyses with electronic structure proposed as being a significant factor

coherent change detection using insar temporal decorrelation model a case study for volcanic ash detection detection of changes caused by major events such as earthquakes volcanic eruptions and floods from interferometric synthetic aperture radar sar data is challenging because of the coupled effects with temporal decorrelation caused by natural phenomena including rain snow wind and seasonal changes the coupled effect of major events and natural phenomena sometimes leads to misinterpretation of interferometric coherence maps and often degrades the performance of change detection algorithms to differentiate decorrelation sources caused by natural changes from those caused by an event of interest we formulated a temporal decorrelation model that accounts for the random motion of canopy elements temporally correlated dielectric changes and temporally uncorrelated dielectric changes of canopy and ground the model parameters are extracted from the interferometric pairs associated with natural changes in canopy and ground using the proposed temporal decorrelation model in addition the cumulative distribution functions of the temporally uncorrelated model parameters which are associated with natural changes in canopy and ground are estimated from interferometric pairs acquired before the event model parameters are also extracted from interferometric sar data acquired across the event and compared with the cumulative probabilities of natural changes in order to calculate the probability of a major event subsequently pixels with cumulative probabilities greater than 75 are marked as changed due to the event a case study for detecting volcanic ash during the eruption of the shinmoedake volcano in january 2011 was carried out using l band advanced land observation satellite palsar data

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

petrogenesis of the lijiagou spodumene pegmatites in songpan garze fold belt west sichuan china evidence from geochemistry zircon cassiterite and coltan u pb geochronology and hf isotopic compositions abstract spodumene and other pegmatites in the lijiagou area are located in the central songpan garze fold belt sgfb west sichuan these pegmatites are hosted within the giant songpan garze polymetallic belt a lack of precise geochronological constraints on the magmatic crystallization of the pegmatite suite and nearby plutonic granitoids has precluded definitive statements on genetic links between spodumene ore formation and the magmatic suite systematic zircon cassiterite and coltan u pb dating hf isotope and whole rock geochemical analysis were undertaken two mica granite and muscovite albite granite have s type granite affinities and chemical compositions suggesting a post orogenic setting and the albite spodumene pegmatites belong to the lct li cs ta group of pegmatites zircon la mc icp ms u pb dating of the two mica granite muscovite albite granite albite pegmatite and albite spodumene pegmatite give crystallization ages of 219 2 2 3 ma mswd 0 55 217 2 8 ma mswd 0 47 202 8 4 9 ma mswd 3 9 and 200 1 4 6 ma mswd 3 1 respectively zircons from the same units yield ehf t values of 39 17 to 6 81 22 73 to 2 83 11 17 to 8 14 and 4 92 to 2 4 respectively consistent with mixed crustal sources for the pegmatite and granite magmas cassiterite from albite spodumene pegmatite yields a concordia intercept age of 211 4 3 3 ma mswd 2 9 while coltan yields a weighted mean age of 211 1 1 0 ma mswd 0 97 the u pb zircon ages of the two mica granite and muscovite albite granite are interpreted as ages of magmatic crystallization metamictization of zircon in both albite and albite spodumene pegmatites makes their u pb zircon ages liable to inaccuracy due to pb loss the coltan u pb age is regarded as an accurate measure of the magmatic crystallization age of the albite spodumene pegmatite given the differences in magmatic ages and ehf t ranges between albite spodumene pegmatite and both the two mica granite and the muscovite albite granite the albite spodumene pegmatites probably represent anatectic melts and not fractionation products of either of the granitic magmas u pb coltan and u pb cassiterite dating are more likely to provide accurate crystallization ages of albite spodumene pegmatites than u pb zircon ages

cassiterite u pb geochronology of the kekekaerde w sn deposit in the baiganhu ore field east kunlun orogen nw china timing and tectonic setting of mineralization abstract the baiganhu w sn ore field in the northwestern area of the east kunlun orogen nw china contains three economically important w sn deposits namely kekekaerde baiganhu and bashierxi timing of the w sn mineralization remains under debates due to lack of precise isotope dating directly conducted on ore minerals we herewith report la mc icp ms laser ablation multi collector inductively coupled plasma mass spectrometry and id tims isotope dilution thermal ionization mass spectrometry cassiterite u pb ages for the kekekaerde w sn deposit in the baiganhu w sn ore field the id tims cassiterite 206 pb 238 u results yield a weighted mean age of 416 1 ma 95 confidence mswd 0 8 and the la mc icp ms analytical data give a 206 pb 207 pb 238 u 207 pb isochron age of 426 13 ma 95 confidence mswd 0 1 these two ages are same within errors suggesting that the mineralization in the baiganhu w sn ore field occurred at ca 416 ma these new ages and understandings are consistent with the previously reported zircon u pb ages of 430 420 ma for the ore bearing granites in the ore field and with the 40 ar 39 ar plateau ages of ca 412 ma for the hydrothermal muscovite from ore bearing quartz veins and greinsenized granite it shows that the granite magmatism and its associated hydrothermal mineralization resulted from the caledonian orogeny that accommodated the closure of the proto tethys followed by the continental collision between the central kunlun northern kunlun terranes and the qaidam block

palsar radiometric and geometric calibration this paper summarizes the results obtained from geometric and radiometric calibrations of the phased array l band synthetic aperture radar palsar on the advanced land observing satellite which has been in space for three years all of the imaging modes of the palsar i e single dual and full polarimetric strip modes and scanning synthetic aperture radar scansar were calibrated and validated using a total of 572 calibration points collected worldwide and distributed targets selected primarily from the amazon forest through raw data characterization antenna pattern estimation using the distributed target data and polarimetric calibration using the faraday rotation free area in the amazon we performed the palsar radiometric and geometric calibrations and confirmed that the geometric accuracy of the strip mode is 9 7 m root mean square rms the geometric accuracy of scansar is 70 m and the radiometric accuracy is 0 76 db from a corner reflector analysis and 0 22 db from the amazon data analysis standard deviation polarimetric calibration was successful resulting in a vv hh amplitude balance of 1 013 0 0561 db with a standard deviation of 0 062 and a phase balance of 0 612deg with a standard deviation of 2 66deg

in situ la mc icp ms and id tims u pb geochronology of cassiterite in the giant furong tin deposit hunan province south china new constraints on the timing of tin polymetallic mineralization abstract the furong deposit located in southern hunan province china is a newly discovered giant tin deposit spatially associated with the a type qitianling granite the petrogenetic link between the giant furong tin deposit and the qitianling granite batholith remains controversial because of the lack of precise dating for the tin polymetallic mineralization here we report for the first time in situ u pb data on cassiterite obtained by la mc icp ms and the results are compared to id tims data the in situ la mc icp ms analyses of the cassiterites provide a reliable age constraint for tin polymetallic mineralization in the furong deposit yielding an isochron age of 159 9 1 9 ma at 95 confidence level mswd 18 which is indistinguishable from the id tims 206 pb 238 u weighted mean age of 158 2 0 4 ma the in situ u pb ages corroborate the ar ar dates published for the furong tin deposit which indicate that the mineralization is coeval with the emplacement of the qitianling granite batholith these results provide further evidence of a close temporal link between the pluton s emplacement and tin mineralization in the furong area the data obtained clearly demonstrate that in situ la mc icp ms u pb dating of cassiterite is a robust geochronometer for direct dating of tin polymetallic mineralization

late cretaceous granitic magmatism and mineralization in the yingwuling w sn deposit south china constraints from zircon and cassiterite u pb geochronology and whole rock geochemistry abstract numerous late cretaceous w sn deposits associated with granitic rocks were developed in the southern part of south china however the relationship among granitic magma mineralization and tectonic setting remains disputed the yingwuling w sn deposit is spatially associated with k feldspar granite and biotite granite in the southwestern part of guangdong province south china la icp ms zircon u pb dating of k feldspar granite biotite granite and weathered ore bearing granites yielded ages of 79 ma which agree well with la icp ms cassiterite u pb age of 79 6 0 9 ma indicating a close genetic link between the yingwuling pluton and w sn mineralization geochemically both k feldspar granite and biotite granite show high sio 2 na 2 o k 2 o and low cao p 2 o 5 contents and they belong to shoshonitic series and high k calc alkaline series respectively high rb sr ratios and low nb ta and zr hf ratios of the yingwuling pluton indicate strong magmatic differentiation compared with k feldspar granite biotite granite experienced a higher degree of fractional crystallization as indicated by lower fe 2 o 3 tio 2 lree sr eu ba and zr contents and higher sio 2 hree rb cs and y contents their sr and nd isotope compositions initial 87 sr 86 sr 0 7027 and 0 7097 e nd t 5 6 and 5 7 are less radiogenic than that of the south china basement thus it is likely that some juvenile materials were involved in the formation of these granitic intrusions this is also favored by the wide range of zircon hf isotope values e hf t 6 6 to 0 8 which indicates mixing processes a type granite affinity of the yingwuling pluton shows that it was possibly formed in an extensional setting late cretaceous w sn deposits constitute an ew trending belt from guangdong to yunnan provinces which was compatible with the northward subduction of the neo tethys plate rather than the northwestward subduction of the pacific plate during late cretaceous combined with previous studies on magmatic rocks and tectonic activities during late cretaceous in south china this study suggests that the subduction of the neo tethys plate was most possibly responsible for the late cretaceous yingwuling granitic intrusion and associated w sn mineralization

age of the dahongliutan rare metal pegmatite deposit west kunlun xinjiang nw china constraints from la icp ms u pb dating of columbite fe and cassiterite abstract dahongliutan is a medium size li be ta nb rare metal pegmatite deposit in the tianshuihai terrane west kunlun orogenic belt nw china in this paper la icp ms u pb ages of columbite fe and cassiterite are reported to constrain the metallogenic age columbite fe with high u and low th yielded a late triassic weighted mean 206 pb 238 u age of 211 9 2 4 ma whilst cassiterite yielded a 206 pb 238 u 207 pb 235 u concordia lower intercept age of 218 12 ma and a tera wasserburg lower intercept age of 218 12 ma which is identical to the columbite fe u pb age and thus represents the emplacement age of the pegmatite dikes the ore hosting pegmatite dikes are intimately time space related to the dahongliutan s type granite ca 220 217 ma indicating that they may have been cogenetic integrating new and published geological data we suggest that the dahongliutan pegmatites may have evolved from the granitic magma represented by the dahongliutan s type pluton in a post collisional tectonic setting regionally the tianshuihai terrane is the western extension of the songpan ganzi block and thus the kunlun li mineralization belt may have been connected to the songpan ganzi li mineralization belt which contains eleven lithium deposits with about 9 8 of li 2 o reserves in china implying that the dahongliutan pegmatite deposit may also have favorable ore forming conditions the similar columbite fe and cassiterite ages demonstrate that these minerals can be precisely dated and could provide useful alternatives to accurately constrain the timing and evolution of rare metal mineralization

a temporal decorrelation model for polarimetric radar interferometers this paper describes a physical model of the temporal changes that occur in vegetated land surfaces observed by a repeat pass radar interferometer we assume the temporal changes to be caused by a gaussian statistic motion of the vegetation elements with motion variance changing along the vertical direction we show that the temporal correlation between two interferometric radar signals is affected by the structural parameters of the vegetation such as canopy height and varies with the wave polarization we validate the model using l band data acquired by the jet propulsion laboratory with the uninhabited aerial vehicle synthetic aperture radar airborne radar this work provides new insights into the role of temporal decorrelation in interferometric radar applications

a novel approach to lead isotope provenance studies of tin and bronze applications to south african botswanan and romanian artifacts lead isotopic ratios of cassiterite the dominant ore of tin evolve after crystallization through decay of uranium u and thorium th to lead pb due to the relatively elevated u pb ratios of this mineral we show that the pb isotopic ratios of smelted tin at rooiberg south africa form an isochron with a model age that matches the known geological age 2 ga of the host granite for the rooiberg cassiterite deposits since the pb isotopic ratios of many prehistoric tin and bronze artifacts throughout southern africa also fall on this isochron we deduce that they were made with tin from either the rooiberg deposits or similar age deposits that exist nearby in addition we show that bronze artifacts from romania define an isochron corresponding to a variscan age 0 3 ga suggesting a central or western european tin deposit as its source since no variscan tin is known from the neighboring carpathian mountains implications of this approach for provenance studies of tin and bronzes around the world are examined given various major tin deposits and their age distribution

miocene sn polymetallic mineralization in the tethyan himalaya southeastern tibet a case study of the cuonadong deposit abstract the cuonadong deposit is located in the cuonadong gneiss dome of the eastern tethyan himalaya and is characterized as a large to superlarge scale sn polymetallic deposit in the himalaya orogen the mineralization pattern includes skarn w sn mineralization in the strong shear zone of the dome mantle hydrothermal sn w veins controlled by north south trending rifts nstrs and be rb mineralization in pegmatitic leucogranite the results of this study show that the zircon u pb age of undeformed postkinematic leucogranites is 15 5 0 1 ma n 28 mswd 1 4 the cassiterite u pb age of the vein type sn w orebody is 14 3 0 5 ma n 40 mswd 3 2 and the muscovite ar ar age of beryl bearing pegmatitic leucogranite is 15 2 0 2 ma mswd 1 5 the isotopic dating results demonstrate that the cuonadong sn w be rb mineralization has a close genetic relationship with the miocene ca 16 14 ma leucogranite magmatic hydrothermal activity in the cuonadong dome the deformed synkinematic two mica granite 18 ma was cut by the sn w ore veins 14 ma faulted by nstrs indicating that the e w trending extension of the nstrs initiated at ca 18 14 ma the himalaya leucogranite belongs to a highly fractionated granite with high sn content 15 ppm in conclusion the himalaya leucogranite is considered to be tin granite in this study and therefore the himalaya presents high potential for sn polymetallic mineralization prospecting

cretaceous granitic magmatism and mineralization in the shanhu w sn ore deposit in the nanling range in south china abstract abundant jurassic cretaceous w sn ore deposits are distributed in the nanling range in south china however the exact mineralization ages relationships between mineralization and granitic rocks and tectonic settings of these deposits remain controversial as a giant quartz vein type w sn deposit hosted in devonian sedimentary strata the shanhu orebodies are featured by located about 4 km far away from the yantianling muscovite granite zircon u pb dating of the yantianling granite yielded ages of 101 0 1 5 ma and 100 4 1 1 ma consistent with cassiterite u pb ages of quartz vein ores 100 2 1 0 ma and 100 5 1 1 ma indicating a close genetic relationship between the granitic magmatism and quartz vein type w sn mineralization the yantianling muscovite granite is characterized by highly silicious 72 01 74 62 wt high alkali na2o k2o 5 32 7 89 wt and strongly peraluminous a cnk 1 11 1 81 the granite is enriched in rb ta nd and u and depleted in sr ti and p it displays right declining chondrite normalized ree patterns with strongly negative eu anomalies and has low nb ta and zr hf ratios indicating that the granite experienced strong magmatic differentiation the yantianling granite has low whole rock end t values 9 5 to 9 3 zircon ehf t values 12 7 to 7 8 and paleoproterozoic model ages the granite belongs to s type and was derived from partial melting of meta sedimentary crust the low ce4 ce3 ratios averaging 47 of zircon from the yantianling granite indicated low oxygen fugacity similar to other w bearing granites in south china this study indicated that cretaceous granitic magmatism in the nanling range also has strong w sn mineralization potential combined with previous studies on coeval magmatic rocks and tectonic activities we propose that the yantianling s type granite and associated w sn mineralization in the nanling range were formed during the regional lithospheric extensional environment

refined insight into 40ar 39ar progressive crushing technique from k cl ar correlations in fluid inclusions abstract hydrothermal fluid activity associated with geological processes can now be dated by 40ar 39ar progressive crushing of minerals thanks to recent advances in high precision mass spectrometry however methods of data analysis and interpretation for these high resolution measurements still need to be refined in this study we report further insights into using k cl ar diagrams as tools for interpreting ages of secondary and primary fluids from 40ar 39ar stepwise crushing experiments three paragenetic mineral pairs of muscovite and wolframites from a southern china tungsten deposit were investigated using the 40ar 39ar technique through laser incremental heating and progressive crushing of single minerals incremental heating analyses of muscovites yielded flat age spectra defining plateau ages of 156 153 ma progressive crushing experiments of wolframites yielded anomalously old apparent ages due to excess 40ar however the apparent ages decline quickly after the initial steps and stabilize to form age plateaus of 156 153 ma without excess 40ar the plateau age steps interpreted as ages of gases derived from primary fluid inclusions pfis yield well defined isochrons with ages ranging from 157 to 153 ma and initial 40ar 36ar values that are indistinguishable from the modern atmospheric value digitally created 2d and 3d diagrams of k cl ar correlations can easily reveal distribution trends and correlation planes from the crushing steps interpretations of these diagrams further reveal the ages of secondary fluid inclusions sfis 87 to 83 ma and primary fluid inclusions pfis 159 to 150 ma raw data from sfis degassed during the initial crushing steps form scatters on inverse isochron plots however 2d and 3d k cl ar diagrams yield sfi ages that agree with 40ar 39ar ages of k feldspar veins cutting the tungsten ore bodies

cassiterite u pb and muscovite40ar 39ar age constraints on the timing of mineralization in the xuebaoding sn w be deposit western china abstract the xuebaoding deposit in the songpan garze orogenic belt western china spatially associated with the xuebaoding granitic complex is a unique pegmatite type sn w be deposit within the giant songpan garze polymetallic belt a lack of precise geochronological constraints on the timing of mineralization for this deposit has precluded definitive statements relating to a genetic link between ore formation and granitoid intrusion up to now to address the temporal relationship between the emplacement of granite and the spatially associated sn w be polymetallic mineralization in the xuebaoding deposit systematic cassiterite u pb and muscovite ar ar dating were undertaken u pb data of cassiterite analyzed by in situ la mc icp ms provided an isochron age of 193 6 6 ma at 95 confidence level mswd 4 the 40 ar 39 ar dating on the muscovite intergrown with the cassiterite sample yielded a plateau age of 194 50 1 02 ma mswd 1 26 and an inverse isochron age of 194 53 1 05 ma mswd 1 34 both the ar ar dates overlap the u pb date within uncertainties placing the timing of tin mineralization at 193 194 ma this is consistent with field geological relationships that show veins cutting marble and granite and with previous sm nd dating within experimental error for scheelite and indicates that sn w polymetallic mineralization at the xuebaoding deposit occurred during the early jurassic combined with previous published trace element and ree data from the xuebaoding granites and other ore minerals as well as the timing of granite emplacement the temporal and genetic associations between granite intrusion events and sn w mineralization of this deposit have been discussed in this paper the results suggest that the pankou granite is genetically related to the polymetallic mineralization in xuebaoding sn w be deposit and further demonstrate that the latest phase of granitic intrusion is commonly favorable for sn and or w mineralization although the pukou granite also exhibits close relationships with the ore formation in its spatial distribution and element characteristics the possibility as a parent for this deposit is excluded duo to the time span from its emplacement to mineralization event that exceed the estimated life of modern geothermal systems

the relationship between ductile shear zone and mineralization in the jiufeng sn deposit northern guangxi south china evidence from structural analysis and cassiterite u pb dating abstract the jiufeng sn deposit is located in the outer contact zone southwest of the neoproterozoic motianling granitic pluton in northern guangxi south china the deposit is characterized by a nne striking 30 200 m wide ductile shear zone named the jiufeng ductile shear zone majority of the sn orebodies including four large ones are hosted by the shear zone field and microstructural observations electron backscatter diffraction measurements and magnetic fabric analyses show that the shear zone is characterized by sinistral thrust shearing the shear zone has also slightly modified the sn orebodies quartz in the shear zone exhibits core mantle structure and undulose extinction quartz has experienced significant sub grain rotation and grain boundary migration recrystallization lattice preferred orientation analysis reveals primarily basal rhomb and prism slips cassiterite grains in the shear zone however demonstrate brittle deformation therefore the deformation temperature during the ductile shearing is estimated lower than 650 c and below u pb closure temperature of cassiterite as such the u pb isotopic composition of the cassiterite was not disturbed by the shearing and the u pb age of the cassiterite could be used for the age of the sn mineralization la icp ms u pb dating of cassiterite grains selected from a cassiterite bearing tourmalinite sample performed in this study yielded a tera wasserburg u pb lower intercept age of 832 3 5 3 ma this age is consistent within error with that of the neighboring neoproterozoic motianling granitic pluton which suggests a close genetic relationship between the sn mineralization and the granitic magmatism studies show that the jiufeng ductile shear zone was produced by a widespread caledonian or kwangsian tectonic event in south china indicating that the shearing was much later than the sn mineralization and has no generic relationship to the sn deposit

a precise u pb age on cassiterite from the xianghualing tin polymetallic deposit hunan south china we report the first precise u pb isotope data on cassiterite from the large xianghualing tin polymetallic deposit in the central nanling district south china the results show that four separates from sample xf 51 have a relatively narrow range of 206pb 238u apparent ages varying from 152 to 157 ma and the three 206pb 238u apparent ages yield a weighted average value of 156 4 ma mswd 0 32 separates from two other cassiterite samples do not have sufficient radiogenic pb to generate a reliable 206pb 238u age seven separates from the above three cassiterite samples define a well constrained 238u 206pb isochron corresponding to an age of 157 6 ma mswd 34 a comparison of the u pb cassiterite ages with published ar ar dates on muscovite from this deposit and k ar age data on biotite from the pluton genetically related to the tin mineralization in this area demonstrates that the u pb isotope system of cassiterite is a potential geochronometer combined with the ar ar dates of muscovite from this deposit we can constrain the absolute age of tin polymetallic mineralization in xianghualing at 154 157 ma the dates obtained in this study consistent with the published geochronological results from other important deposits in this region reveal that the large scale tungsten tin mineralization in the central nanling region was predominantly emplaced during 150 161 ma

use of optical and radar remote sensing satellites for identifying and monitoring active inactive landforms in the driest desert in saudi arabia abstract observing earth from the space is key for monitoring land surface dynamics and probing near surface geomorphic and geological features including those obscured by sand sheets dunes and human activity the hyper arid area of the arabian peninsula was selected for detecting and extracting obscure paleohydrological systems and modeling the spatio temporal dynamics of sand dunes using synthetic aperture radar sar and optical high resolution remote sensing images interferometric synthetic aperture radar insar coherence change detection ccd using sentinel 1 imagery was performed revealing subtle changes in the surficial landforms of the study area these images also discriminated between active and inactive geomorphic features in addition low frequency l band advanced land observing satellite phased array type l band synthetic aperture radar alos palsar and shuttle radar topography mission srtm data revealed the details of paleochannels in the basins that drain into the arabian gulf these ephemeral rivers are the source of sand that was later reshaped into dunes by aeolian processes the results also revealed that the morphology and extension of dunes were clearly influenced by topography slope and wind velocity and direction rather than human activities knowledge gained by exploring desert features is essential for planning settlements and development and integrated approaches using a variety of remote sensing datasets are key for enhancing earth observation across a range of spatial and temporal scales

genesis of the gaosong sn cu deposit gejiu district sw china constraints from in situ la icp ms cassiterite u pb dating and trace element fingerprinting abstract the gaosong sn cu deposit in the gejiu ore district sw china is a large cassiterite sulfide deposit hosting total ore reserves of 67 4 mt 1 3 sn and 19 0 mt 1 1 cu two types of mineralization developed in the deposit i e cassiterite sulfide ore within the proximal skarn in contact with the gaofengshan biotite granite and fault controlled stratiform like cassiterite iron oxide sulfide ore in the distal carbonate country rock cassiterite grains are disseminated in both ores in situ u pb dating of one cassiterite sample from the cassiterite sulfide ore and two from the cassiterite iron oxide sulfide ore yielded weighted mean 206pb 238u ages of 84 3 1 4 ma 85 1 1 0 ma and 83 5 2 1 ma respectively the three mineralization ages are consistent with the emplacement age of the gaofengshan granite 85 8 0 6 ma within error suggesting a close temporal link between tin mineralization and granitic magmatism cassiterite grains can be divided into two types based on cathodoluminescence cl illustrations namely euhedral cst i and veinlet like cst ii in the cassiterite sulfide ore cst i has clear oscillatory zonation and is dull luminescing in the cassiterite iron oxide sulfide ore cst i core is dull luminescing blue in om cl and surrounded by a bright luminescing cst i rim yellow in om cl cst i is replaced by cst ii veinlets with bright luminescing yellow in om cl the sem cl luminescing intensity of cassiterite is mainly controlled by ti content elevated w and fe but low nb ta zr and hf concentrations of cassiterites from the gaosong deposit are distinctly different from those of cassiterites in vms sedex tin deposits but similar to those from granite related tin deposits the late cretaceous crystallization ages and trace element characteristics demonstrate that cassiterites from both ores were formed in a magmatic hydrothermal system associated with the gaofengshan granite and preclude the sedex origin of the stratiform like cassiterite iron oxide sulfide ore

major and trace elements of stream sediments from the lowermost amazon river geochemical results from river bottom sediments taken from the lowermost amazon river are presented bedload sediments were analyzed for 10 major and 38 minor elements mud bulk sediments exhibit a tendency to a slight enrichment in cr mn rb sr zr cs ba and hf pointing to the importance of these elements in the silt fraction generally cu zn rb cs ba and sn are clearly associated with clay minerals while y zr hf th and u are associated with heavy minerals the location of this area in an intensive chemical weathering environment results in the strong modification of sediment composition chemical weathering processes strongly modify original sediment composition and can be recognized apart from provenance processes on the basis of their geochemical signature discriminant analysis makes the detection of less marked differences in sediment characteristics possible thus improving the accuracy of distinctions between groups the amazon mouth and xingu mouth xm are discriminated principally by the textural maturity of their sediments the jari mouth jm shows highest co and fe2o3 contents despite similarities between the amazon north branch anb and amazon south branch asb the anb can be differentiated on the basis of its higher sr p2o5 and na2o contents the asb on the basis of its higher zn mno and cao contents and the estreitos de breves est based on its higher abundance of ni and cu higher contents in p2o5 fe and mn are related to laterite covers

direct dating of tin tungsten mineralization of the piaotang tungsten deposit south china by 40ar 39ar progressive crushing abstract dating ore minerals is the most direct method to determine the mineralization age of a deposit but only a few ore minerals can be directly dated by traditional isotopic geochronometers the aim of this study is to investigate the possibility of direct dating of the ore minerals cassiterite and wolframite from the piaotang tungsten deposit using the 40ar 39ar stepwise crushing technique comparing the age to coexisting k rich muscovite dated by 40ar 39ar laser stepwise heating the cassiterite wolframite and muscovite samples were separated from four pieces of ore hand specimens the 40ar 39ar isochron ages of cassiterite and wolframite are concordant with ages of their coexisting muscovite indicating that cassiterite and wolframite are suitable ore minerals for directly dating the ore forming event by 40ar 39ar stepwise crushing

sm nd dating of hydrothermal carbonate formation an example from the breitenau magnesite deposit styria austria abstract the geochemical evolution and chronology of the breitenau sparry magnesite deposit has been investigated by means of major and trace element abundances stable c o isotope and sm nd isotope analysis chemically separated magnesite fractions leachates show consistent light ree depleted rey patterns marine carbonate normalized and nearly constant normalized values for the middle and heavy ree without significant ce eu or y anomalies non carbonate residues composed of dark matrix material are high in al 2 o 3 and show variably light to middle ree enriched rey patterns similar to shales leachates of limestone from nearby country rocks have normalized rey patterns similar to marine carbonates only ce and y are slightly fractionated based on their trace element chemistry and normalized rey patterns leachates of dolomite from the margin of the deposit closely resemble either limestone type a or magnesite type b with one exception 18 o vpdb for both dolomite types is within the range of the respective magnesite values 18 o vpdb c 14 2 to 15 7 leachates of dolomite from druses within the deposit type c show low rey abundances with normalized patterns similar to those of magnesite sm nd isotope data for magnesite leachates yield a well defined isochron age of 222 5 9 8 ma mswd 3 1 isochron calculations for leachate s and residue s from individual magnesite samples internal isochrons yield ages between 236 16 ma and 193 5 8 6 ma with a low degree of scatter mswd 18 o vpdb c 15 2 37 9 5 4 ma 18 o vpdb c 12 5 and 3 1 7 6 8 ma 18 o vpdb c 11 type c dolomite data indicate that druses were formed by open system fluid flow throughout the deposit

in situ la icpms u pb dating of cassiterite without a known age matrix matched reference material examples from worldwide tin deposits spanning the proterozoic to the tertiary abstract cassiterite sno2 a main ore mineral in tin deposits is suitable for u pb isotopic dating because of its relatively high u pb ratios and typically low common pb we report a la icpms analytical procedure for u pb dating of this mineral with no need for an independently dated matrix matched cassiterite standard la icpms u th pb data were acquired while using nist 612 glass as a primary non matrix matched standard raw data are reduced using a combination of iolite and other off line data reduction methods cassiterite is extremely difficult to digest so traditional approaches in la icpms u pb geochronology that utilize well characterized matrix matched reference materials e g age values determined by id tims cannot be easily implemented we propose a new approach for in situ la icpms dating of cassiterite which benefits from the unique chemistry of cassiterite with extremely low th concentrations th u ratio of 10 4 or lower in some cassiterite samples accordingly it is assumed that 208pb measured in cassiterite is mostly of non radiogenic origin it was initially incorporated in cassiterite during mineral formation and can be used as a proxy for common pb using 208pb as a common pb proxy instead of 204pb is preferred as 204pb is much less abundant and is also compromised by 204hg interference during the la icpms analyses our procedure relies on 208pb 206pb vs 207pb 206pb pb pb and tera wasserburg 207pb 206pb vs 238u 206pb u pb isochron dates that are calculated for a 1 54 ga low th cassiterite reference material with varying amounts of common pb that we assume remained a closed u pb system the difference between the nist 612 glass normalized biased u pb date and the pb pb age of the reference material is used to calculate a correction factor f for instrumental u pb fractionation the correction factor f is then applied to measured u pb ratios and tera wasserburg isochron dates are obtained for the unknown cassiterite analyzed in the same analytical session this allows for u pb dating of cassiterite of any age with no need for an independently dated matrix matched reference material nor assumptions about the isotopic composition of common pb results for cassiterite from tin deposits in bolivia brazil china russia saudi arabia south africa spain and the united kingdom with ages ranging from 20 ma to 2060 ma demonstrate the applicability of this approach across a broad range of geologic time these ages are in good agreement with published geochronology of the host rocks associated with the tin deposits and with previously published u pb ages of some cassiterites from the same deposits thus our in situ la icpms methodology verifies the use of cassiterite as a reliable u pb mineral geochronometer with the advantages of fast and relatively low cost in situ analyses with moderate spatial resolution

stratigraphy grain size and component characteristics of the 2011 shinmoedake eruption deposits kirishima volcano japan abstract the 2011 eruption of shinmoedake volcano part of kirishima volcanic complex in southern kyushu southwestern japan was characterized by a significant change in eruption style from subplinian eruptions to lava effusion in the summit crater and subsequent vulcanian eruptions the stratigraphy distribution and textures of fallout tephra deposits reveal the character and sequence of the eruption the tephra fall deposits distributed southeast of the volcano are divided into five units based on the eruptive events unit 1 is a lithic rich fine ash fall deposited on 19 january 2011 unit 2 is a very well to well sorted pumice fall deposit from the evening of january 26 to early morning of january 27 and is the main product of the 2011 eruption the unit 2 deposit was dispersed throughout an area extending more than 20 km se of the source crater unit 3 comprises tephra fall deposits related to the january 27 15 h 41 min explosion and is subdivided into lower 3l and upper 3u parts unit 3l is a lithic rich well sorted coarse ash fall deposited during the initial stage of the january 27 15 h 41 min eruption whereas the unit 3u is composed mainly of coarse grained pumiceous lapilli unit 4 is a fine ash fall deposited on january 28 29 and consists mostly of fresh lava fragments and crystal grains unit 5 is a product of the largest vulcanian eruption on march 13 unit 5 tephra is a lithic rich medium to coarse ash fall deposit furthermore the 31 august 2011 ash fall deposit extending 19 km southwest of the shinmoedake crater is fine grained and contains abundant lava fragments temporal variations in grain size and components of the 2011 eruption deposits reveal the eruption sequence and the conditions of the crater conduit and magma chamber

neoproterozoic tin mineralization in south china geology and cassiterite u pb age of the baotan tin deposit in northern guangxi the baotan tin deposit 23 mt 0 43 sn is located in the jiuwandashan yuanbaoshan area south china it is hosted in neoproterozoic mafic metasedimentary rocks and apical portions of the pinying granite pluton six alteration and mineralization stages have been identified pre ore alteration cassiterite greisen cassiterite tourmaline quartz vein cassiterite quartz vein cassiterite sulfide vein and post ore quartz calcite quartz vein stages tin mineralization is mainly in the cassiterite greisen cassiterite tourmaline quartz and cassiterite quartz vein stages the deposit is characterized by widespread tourmalinization both pre ore and ore stage tourmaline is schorl tourmaline from pre ore tourmaline quartz nodules has elevated al2o3 and f contents and fe fe mg and na na ca ratios which are probably controlled by the initial magmatic fluid ore stage tourmaline shows low al2o3 and f contents and fe fe mg and na na ca ratios which are likely influenced by the surrounding mafic rocks la icp ms u pb dating on two cassiterite samples from disseminated cassiterite tourmaline quartz ore and cassiterite quartz vein yields 206pb 238u weighted mean ages of 832 5 ma and 834 4 ma 2 respectively these two dates are consistent with the previously reported zircon u pb ages of 834 835 ma for the pingying granite which indicates that tin mineralization is related to the granite the granite has low magnetic susceptibility and zircon ce4 ce3 ratios which are similar to those of sn bearing ilmenite series granites our study confirms the neoproterozoic tin mineralization event in south china and indicates that the neoproterozoic highly fractionated s type granites in the southeastern margin of yangtze block have a great potential for tin mineralization

in situ u pb geochronology and sulfur isotopes constrain the metallogenesis of the giant neves corvo deposit iberian pyrite belt abstract the large scale high grade sn ores and the cu sn metal association in the volcanic massive sulfide vms ores in neves corvo are unique among vms deposits not only in the iberian pyrite belt but also worldwide thus the exceptional nature of the neves corvo deposit calls for unusual metallogenic processes previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization this has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and vms style mineralization or is the result of later processes events associated with the hercynian orogeny we report in situ u pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the neves corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore forming fluids the cassiterite samples yield u pb ages of the sn mineralization of 363 366 ma identical to the age of the host volcanic rocks 34s values range from 32 3 to 17 4 among the different vms ore types and are largely consistent with microbiological reduction of seawater sulfate but with some positive values resulting from thermochemical sulfate reduction in contrast the sn rich ores have a limited range in 34s that clusters near 0 which suggests derivation from magmatic fluids hence the unusually high sn grades at the neves corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and vms mineralization

cassiterite la mc icp ms u pb and muscovite 40 ar 39 ar dating of tin deposits in the tengchong lianghe tin district nw yunnan china the tengchong lianghe tin district in northwestern yunnan china is an important tin mineralization area in the sanjiang tethyan metallogenic domain there are three n s trending granite belts in the tengchong lianghe area with emplacement ages ranging from early cretaceous to late cretaceous and early cenozoic tin mineralization is spatially associated with these granitic rocks however the petrogenetic link between the tin deposits and the host granites is not clear because of the lack of age data for the tin mineralization we investigate the possibility of direct dating of cassiterite from three typical tin deposits in the tengchong lianghe tin district using laser ablation multicollector inductively coupled plasma mass spectrometry la mc icp ms in situ la mc icp ms dating of seven cassiterite samples from the lailishan lls 1 and lls 2 xiaolonghe xlh wds dsp and hjs and tieyaoshan tys tin deposits yielded well defined 206pb 207pb 238u 207pb isochron ages to assess the accuracy of the in situ u pb dating of cassiterite 40ar 39ar dating of coexisting muscovite in samples lls 1 dsp and tys was also performed the cassiterite in situ u pb ages 47 4 2 0 71 9 2 3 and 119 3 1 7 ma respectively are in excellent agreement with the coexisting muscovite 40ar 39ar ages 48 4 0 3 71 9 1 4 and 122 4 0 7 ma respectively the u pb ages of cassiterite combined with the 40ar 39ar ages of muscovite indicate that there are three tin mineralization events in this district the lailishan tin deposit at 47 4 2 0 to 52 2 7 ma the xiaolonghe tin deposit at 71 6 2 4 to 3 9 2 0 ma and the tieyaoshan tin deposit at 119 3 1 7 to 122 5 0 7 ma these ages are highly consistent with the zircon u pb ages of the host granites it is su ggested that the cretaceous tin mineralization might have taken place in a subduction environment while the early tertiary tin metallogenesis was in a postcollisional geodynamic setting

c band repeat pass interferometric sar observations of the forest properties of ers 1 c band repeat pass interferometric sar information for a forested area are studied the intensity information is rather limited but including coherence and effective interferometric sar insar height more information about the forest parameters can be obtained via satellite such information is also important for correction of insar derived topographic maps coherence properties have been used to identify forested nonforested areas and the interferometric effective height of the forest determined by comparison to a dem of the area the authors have developed a model to relate basic forest properties to insar observations these show that the coherence and interferometric effective height of a forested area change between image pairs the model demonstrates how these properties are related to the temporal decorrelation and the scattering from the vegetation canopy and the ground surface gaps in the vegetation are found to be important in the characterization of boreal forests

late cretaceous granitic magmatism and sn mineralization in the giant yinyan porphyry tin deposit south china constraints from zircon and cassiterite u pb and molybdenite re os geochronology the yinyan porphyry tin deposit in western guangdong is spatially associated with quartz porphyry and granite porphyry la icp ms zircon u pb dating defined an emplacement age of 78 5 0 4 ma for the quartz porphyry and 79 2 0 9 ma for the granite porphyry la icp ms cassiterite u pb dating yielded tera wasserburg lower intercept ages of 78 5 0 6 78 6 1 2 and 78 2 0 7 ma for cassiterite from a cassiterite sulfide vein cassiterite sulfide ore and a cassiterite topaz quartz stringer respectively re os dating of molybdenite from seven different veins yielded an isochron age of 77 0 0 5 ma all these new age data are indistinguishable within analytical uncertainty and therefore indicate a genetic relationship between the sn mineralization and the porphyry magmatism in the yinyan deposit the ree tetrad effect and very low nb ta and zr hf ratios indicate that the quartz porphyry and the granite porphyry are highly evolved the u pb dated cassiterite is enriched in fe w and u and in high field strength elements hfses such as zr hf nb and ta the high fe nb and ta contents may be responsible for the dark luminescence of cassiterite in cl images the zr hf ratio of cassiterite may potentially be used to distinguish the mineralization type cassiterite from pegmatites has lower zr hf ratios 5 6 in comparison with granite greisen related 9 30 cassiterite cassiterite from the early hydrothermal stage typically contains higher amounts of ti nb ta zr and hf than that from the late hydrothermal stage in combination with published geochronological data of other sn w deposits in the western guangdong province two sn w metallogenic events at ca 85 and 77 80 ma have been identified these two metallogenic events are part of a larger scale 75 100 ma sn w mineralization event in south china which we suggest was probably related to the subduction of the neo tethyan oceanic plate

single baseline polarimetric sar interferometry examines the application of single baseline polarimetric sar interferometry to the remote sensing and measurement of structure over forested terrain for this a polarimetric coherent scattering model for vegetation cover suitable for the estimation of forest parameters from interferometric observables is introduced discussed and validated based on this model an inversion algorithm which allows the estimation of forest parameters such as tree height average extinction and underlying topography from single baseline fully polarimetric interferometric data is addressed the performance of the inversion algorithm is demonstrated using fully polarimetric single baseline experimental data acquired by dlr s e sar system at l band

u pb and reconnaissance lu hf isotope analysis of cassiterite and columbite group minerals from archean li cs ta type pegmatites of western australia abstract lithium cesium tantalum pegmatites represent a valuable global source of rare metals however the crustal processes that facilitate the generation of li cs ta pegmatite melts are not fully understood knowledge of the timing melt sources and tectonic setting of this class of rare element pegmatite is limited in particular by the availability of geochronological and other isotopic data this study presents new geochronological data from li cs ta pegmatites across western australia that vary in age host lithology and geodynamic setting by applying in situ la icpms u pb methods to date columbite group minerals and cassiterite samples in a novel approach reconnaissance lu hf isotope data obtained from cassiterite samples by la mc icpms are also reported providing insights into the source of li cs ta pegmatite melts the crystallisation ages and lu hf isotopic data collected from the li cs ta type pegmatites are interpreted within the existing magmatic and tectonic framework of their host terranes and commonalities are identified li cs ta pegmatites are found to have been emplaced late in regional tectonic history and to follow periods of extended crustal reworking

genesis of tin dominant polymetallic deposits in the dachang district south china insights from cassiterite u pb ages and trace element compositions abstract the dachang tin dominant polymetallic district in western south china hosts a total reserve of 110 mt ore 1 sn 3 5 by products of zn pb sb in and cu and 100 to 300 g t ag economic tin orebodies in the district mainly developed in devonian limestone black shale and siliceous rocks as massive stratiform and vein stockwork mineralization la icp ms u pb dating on seven cassiterite samples from the tongkeng changpo and gaofeng sn zn pb deposits and the dafulou huile and kangma sn zn deposits yields weighted mean 206pb 238u ages ranging from 90 3 1 8 ma to 95 4 4 9 ma these dates are significantly younger than the devonian ore hosted strata but agree well with the previously published zircon u pb ages of 96 6 93 9 ma for the longxianggai biotite granite within analytical uncertainties showing a close temporal link between the granitic magmatism and tin mineralization cassiterite grains from various ore types in the dachang district show clear growth zonations as reflected from their cathodoluminescence images la icp ms trace element analyses of cassiterite grains indicate that they have relatively high ti fe and w but low nb and ta contents which corresponds to the clear luminescencing chemical variations of cassiterite from different ore types i e cassiterite sulfide ores and cassiterite bearing quartz veins are indistinguishable except for more enriched fe in cassiterite from cassiterite quartz veins combined with cretaceous u pb ages elevated fe and w contents of cassiterite suggest tin dominant polymetallic deposits in the dachang district were formed in a granite related magmatic hydrothermal system controlled by the longxianggai biotite granite precluding their syngenetic origin

decorrelation of l band and c band interferometry over vegetated areas in california temporal decorrelation is one of the main limitations for recovering interseismic deformation along the san andreas fault system using interferometric synthetic aperture radar to assess the improved correlation properties of l band with respect to c band we analyzed l band advanced land observation satellite alos interferograms with a range of temporal and spatial baselines over three vegetated areas in california and compared them with corresponding c band european remote sensing satellite ers interferograms over the highly vegetated northern california forests in the coast range area alos remains remarkably well correlated over a 2 year period whereas an ers interferogram with a similar temporal and spatial baseline lost correlation in central california near parkfield we found a similar pattern in decorrelation behavior which enabled the recovery of a fault creep and a local uplifting signal at l band that was not apparent at c band in the imperial valley in southern california both alos and ers have low correlation over farmlands alos has lower correlation over some sandy surfaces than ers probably due to low signal to noise ratio in general l band interferograms with similar seasonal acquisitions have higher correlation than those with dissimilar season for both l and c band correlation over vegetated areas decreases with time for intervals less than 1 year and then remains relatively constant at longer time intervals the decorrelation time for l band is more than 2 years in the forest in california whereas that for c band is less than 6 months overall these results suggest that l band interferograms will reveal near fault interseismic deformation once sufficient data become available

combined zircon molybdenite and cassiterite geochronology and cassiterite geochemistry of the kuntabin tin tungsten deposit in myanmar

cassiterite potential for direct dating of mineral deposits and a precise age for the bushveld complex granites u pb and pb isotopic measurements of cassiterite from the 200 ma tin deposits of belitung indonesia and 2100 ma zaaiplaats deposit in south africa demonstrate that cassiterite can be used to directly date mineral deposits rather than associated minerals such as zircon and rutile a precise u pb age of 2099 3 ma has been determined for cassiterites hosted in granites from the bushveld complex on conventional 207 pb 204 pb 206 pb 204 pb plots the data for the indonesian deposits give an age apparently older than that obtained from u pb plots perhaps indicative of inheritance of pb from an older source

neoproterozoic mineralization in a hydrothermal cassiterite sulfide deposit at jiumao northern guangxi south china mineral scale constraints on metal origins and ore forming processes abstract most tin deposits worldwide are inferred to have formed from fluids derived from evolved granitic magma systems neoproterozoic silicate and sulfide stage sn deposits at jiumao of south china in contrast have been thought to be derived from metasedimentary and mafic ultramafic host rocks the sn deposit may thus have formed by components and processes distinct from those that commonly contribute to sn deposits although spatially associated greisen hosted sn deposits also occur to characterize in detail the formation of the jiumao ore deposits which contain 28 000 t of sn we present new field and petrographic observations major and trace element compositions for silicate and ore minerals and u pb age data of cassiterites and zircons for the deposits and granites our research shows that 1 the granite greisen system formed at 830 ma which is the earliest sn mineralization event in south china 2 the silicate and sulfide stage ores in the country rocks formed at an fo2 of nno with temperatures of 350 c and 170 c respectively 3 all vein type sn ores at jiumao were formed by sn f b rich fluids that were derived from the yuanbaoshan granite magma system rather than ultramafic rocks 4 the fe rich character of the ores hosted by the metasedimentary rocks and the mg rich character of the ores hosted by the ultramafic rocks largely controlled the reactions and efficacy of cassiterite precipitation and thus ore grade we highlight that differences in mineral assemblages largely relate to differences of the protolith compositions and fluid rock reactions e g b and tourmaline deposition in the ores hosted by the metasedimentary rocks but not in the ores hosted by the ultramafic rocks cassiterite and titanite trace element compositions reflect fluid composition protolith composition and intensive parameters of crystallization

the xiling sn deposit eastern guangdong province southeast china a new genetic model from 40ar 39ar muscovite and u pb cassiterite and zircon geochronology

data for s isotopic geochemistry zircon and cassiterite u pb geochronology of the haobugao sn polymetallic deposit southern great xing an range ne china abstract the southern great xing an range sgxr is the most important tin polymetallic metallogenic belt in north china the lack of previous research on the genesis of the tin mineralization especially its exact age prevents development of a deep understanding of tin deposits in this area haobugao sn polymetallic deposit is a large skarn type deposit in the huangang ganzhuermiao sn fe cu pb zn ag metallogenic belt in the sgxr the ore body occurs in the contact zone between a yanshanian intrusion and permian dashizhai formation marble 34 s v cdt values of sulfides from the haobugao sn polymetallic deposit range from 4 7 to 3 5 with an average of 0 65 and these values strongly indicate a deep magmatic source for the sulfur in the ore minerals of the deposit in this paper we also report the results of la icp ms u pb dating of tin mineralization in no i ore body and of the underlying granite cassiterite from no 1 ore body deposited at 139 0 6 ma and the closely associated granite has an age of 142 9 1 6 ma the similar ages indicate that the tin mineralization was produced by early cretaceous magmatic hydrothermal activity these results together with the ages of other tin deposits and related granites indicate extensive granitic magmatism and tin mineralization during the early cretaceous in the southern segment of the great xing an range

the 190pt 186os decay system applied to dating platinum group element mineralization of the bushveld complex south africa abstract we evaluate the 190pt 186os decay system measured by laser ablation mc icpms as a useful geochronometric tool for direct dating of platinum group minerals pgm in large mafic ultra mafic intrusions by analysing mineralised rocks from the geochronologically well constrained bushveld complex s africa mixed pgm laurite cooperite laurite platarsite sperrylite and pt fe alloy from the merensky reef yield a pt os isochron age of 1995 50 ma 2 n 48 mswd 1 16 initial 186os 188os 0 119819 0 000006 while this is 59 myr younger than the u pb zircon age for the merensky reef scoates and friedman 2008 it is consistent with recent re os ages for the platreef considering the younger age recorded by both re os and pt os systems we propose that the pt os isochron age records a late low temperature hydrothermal event affecting pgm and sulphides in the platreef and merensky reef pt rich phases may also yield single grain 190pt 186os model ages since initial 186os 188os can be well constrained a pt os model age of 2024 ma 101 ma was calculated for a merensky cooperite a pt fe alloy from the onverwacht pipe and a tweefontein hill sperrylite give pt os model ages of 2113 106 ma and 2042 102 ma respectively a pt os isochron derived from all bushveld units gives an age of 2012 47 ma 2 186os 188osi 0 119818 0 000006 with an mswd of 1 19 hence pge mineralisation in different stratigraphic horizons of the complex cannot be distinguished temporally using the pt os chronometer nonetheless the potential for the pt os system in dating events in pge mineralised systems is evident and the agreement of single grain model ages in high pt os phases with the pt os and re os isochron ages indicates their usefulness in the geochronology of these systems

constraints of in situ zircon and cassiterite u pb molybdenite re os and muscovite 40ar 39ar ages on multiple generations of granitic magmatism and related w sn mineralization in the wangxianling area nanling range south china abstract the nanling range in south china hosts numerous w sn rare metal deposits associated with several cycles of polygenetic granitic intrusions in the wangxianling area of the middle nanling range igneous intrusions include the wangxianling and hehuaping granite plutons and more than 20 granite porphyry dykes the wangxianling pluton has a central phase of medium grained tourmaline two mica granite and a marginal phase of medium grained tourmaline muscovite granite the pluton hosts several tungsten deposits including shuiyuanshan and yejiwo mineralization type is dominantly scheelite greisen with subordinate scheelite skarn and wolframite quartz veins the hehuaping pluton composed of coarse grained biotite granite and granite porphyry dykes to the east of the wangxianling pluton have an associated hehuaping tin deposit with tin skarn and subordinate porphyry and greisen mineralization in situ zircon and cassiterite u pb dating molybdenite re os and muscovite 40ar 39ar dating techniques are used to refine the age spectra of granitic rocks and w sn mineralization in the wangxianling area granites of the wangxianling pluton have zircon u pb ages of 224 ma tungsten bearing quartz veins from both the shuiyuanshan and yejiwo tungsten deposits have an average molybdenite re os isochron age of 224 ma and muscovite of scheelite greisen from the shuiyuanshan tungsten deposit yields a 40ar 39ar plateau age of 214 ma the two mineralization ages are consistent with the zircon u pb age of the wangxianling pluton indicating a close association between pluton emplacement and w mineralization in the late triassic both the hehuaping pluton and granite porphyry dykes have zircon u pb ages of 156 ma in situ la icp ms u pb dating of cassiterite in both the tin skarn and tin greisen yields an average age of 156 ma showing that the sn mineralization occurred at a similar time to the late jurassic granitic magmatism thus two mineralization events are identified in the wangxianling area and include an earlier w dominant mineralization event and a later sn dominant mineralization event the earlier event is related both spatially and temporally to intrusion of the late triassic s type wangxianling granite pluton whereas the later mineralization is associated both spatially and temporally with intrusion of the late jurassic hehuaping a2 type granite pluton and a2 type granite porphyry dykes

cassiterite u pb geochronology constrains magmatic hydrothermal evolution in complex evolved granite systems the classic erzgebirge tin province saxony and bohemia

combined zircon and cassiterite u pb dating of the piaotang granite related tungsten tin deposit southern jiangxi tungsten district china abstract the large low grade piaotang w sn deposit in the southern jiangxi tungsten district of the eastern nanling range south china is related to a hidden granite pluton of jurassic age the magmatic hydrothermal system displays a zonation from an inner greisen zone to quartz veins and to peripheral veinlets stringers five floor zonation model most mineralization is in quartz veins with wolframite cassiterite the hidden granite pluton in underground exposures comprises three intrusive units i e biotite granite two mica granite and muscovite granite the latter unit is spatially associated with the w sn deposit combined la mc icp ms u pb dating of igneous zircon and la icp ms u pb dating of hydrothermal cassiterite are used to constrain the timing of granitic magmatism and hydrothermal mineralization zircon from the three granite units has a weighted average 206pb 238u age of 159 8 0 3 ma 2 mswd 0 3 the cathodoluminescence cl textures indicate that some of the cassiterite crystals from the wolframite cassiterite quartz vein system have growth zonations i e zone i in the core and zone ii in the rim dating on cassiterite zone ii yields a weighted average 206pb 238u age of 159 5 1 5 ma 2 mswd 0 4 i e the magmatic and hydrothermal systems are synchronous this confirms the classical model of granite related tin tungsten mineralization and is against the view of a broader time gap of 6 myr between granite magmatism and w sn mineralization which has been previously proposed for the southern jiangxi tungsten district the elevated trace element concentrations of zr u nb ta w and ti suggest that cassiterite zone ii formed in a high temperature quartz vein system related to the piaotang granite pluton

a possible linkage between highly fractionated granitoids and associated w mineralization in the mesozoic yaogangxian granitic intrusion nanling region south china abstract the yaogangxian ygx w deposit in the central nanling w province south china is one of the largest w deposits worldwide both vein type wolframite and skarn type scheelite orebodies were exposed in ygx these scheelite and wolframite mineralization are spatially associated with the ygx granitic intrusion the exposed intrusion contains two main intrusive phases lower zone coarse grained two mica granite and upper zone fine grained muscovite granite an integrated study of whole rock geochemistry la icp ms zircon u pb geochronology and zircon hf isotopic geochemistry of the ygx granitic intrusion was undertaken to constrain its magmatic source and petrogenesis cassiterite la icp ms u pb dating was also undertaken to constrain the connection between the intrusion and hydrothermal w mineralization zircon u pb dating yielded weighted mean ages of 161 3 and 157 2 ma for the two mica and muscovite granites respectively cassiterite crystals from wolframite quartz veins display growth zonation under cathodoluminescence and have a weighted mean zircon u pb age of 158 2 ma the formation of the muscovite granite and related w mineralization in the ygx deposit was thus initiated during the early yanshanian the ygx granites display typical metaluminous to strongly peraluminous characteristics with high sio2 73 5 79 1 wt and k2o 3 0 5 0 wt contents they are enriched in heavy rare earth elements rees comparative to light rees notably they exhibited strong negative eu anomalies and are depleted in sr ba p and ti in addition muscovite granites in ygx are more significantly enriched in heavy rees relative to light rees than two mica granites indicating that the former experienced higher degree fractionation than the latter zircon grains of the ygx granitoids have strongly negative ehf t 15 to 10 3 with two stage hf model ages of 2 15 1 86 ga indicating a magma source of reworked ancient crustal material without obvious involvement of juvenile materials the results of petrology and geochemistry indicate that the ygx granitic intrusion is a highly fractionated s type granite emplaced during widespread 160 150 ma granitic magmatism in the nanling region further evolution to late stage for multiphase ygx granitic intrusion is needed to enrich ore forming elements after magmatic emplacement it is suggested that the extensional environment of continental lithosphere caused by the northwest subduction of the paleo pacific plate may play an key role in the genesis of ygx s type granite w rich proterozoic basement rocks and fractional crystallization may provide material for the formation of the granite related tungsten mineralization

a new method for u pb geochronology of cassiterite by id tims applied to the mole granite polymetallic system eastern australia abstract we present a new method for precisely determining the u pb isotopic composition of cassiterite by isotope dilution thermal ionisation mass spectrometry id tims complete sample dissolution and spike sample equilibration is accomplished in a pressure vessel with hbr isolation of small quantities of u and pb from the tin rich matrix is based on a novel tru spec column separation with total procedural blanks of yuan et al 2011

near field ground motions and shaking from the 2019 mw 7 1 ridgecrest california mainshock insights from instrumental macroseismic intensity and remote sensing data

40ar 39ar ages of precambrian manganese ore minerals from sweden india and morocco in order to test their chronometric potential 40ar 39ar stepheating and 4he analyses have been carried out on five manganese ore minerals of the hollandite cryptomelane series from three precambrian manganese deposits ultevis sweden sitapar india bachkoun morocco samples from the metamorphic occurrences ultevis and sitapar yielded ar ages of 1 8 ga and 0 95 ga interpreted as the age of postmetamorphic cooling hollandites ultevis and of an early k introducing alteration process subsequent to amphibolite facies metamorphism cryptomelanes sitapar both data are consistent with known chronologies of the svecokarelian and satpura orogenic cycles a date of 670 ma obtained for a hollandite from a volcanogenic vein deposit bachkoun however contrasts with published extrusion ages of 580 560 ma for the volcanic host rocks ouarzazate series probably due to incorporation of excess argon the use of the 40ar 39ar technique together with multiple isotope systematics made it nevertheless possible to establish a reasonable estimate of a mineralization age close to 580 ma measurement of fractional ar losses during vacuum step heating 500 1600 c although indicating good ar retentivities failed to define model diffusion parameters because of non linear arrhenius arrays helium diffusion results 200 1200 c indicated retention of radiogenic 4he by the samples corroborated by u he mineral dates between 0 96 and 0 31 ga potassium bearing manganese oxides are therefore able to retain argon possibly also 4he through geological times and may thus provide ages of ore forming processes and perhaps later cooling and alteration stages

paleomagnetism of a lateritic paleoweathering horizon and overlying paleoproterozoic red beds from south africa implications for the kaapvaal apparent polar wander path and a confirmation of atmospheric oxygen enrichment the olifantshoek group in southern africa contains paleoproterozoic red beds that are exceptionally well preserved lying unconformably atop a regionally extensive lateritic paleoweathering profile we studied the basal unit of this succession known as the gamagara or mapedi formation and the lateritized substrate so called drakenstein or wolhaarkop paleosol on which it developed two ancient magnetic components are observed one int usually with a distributed unblocking spectrum between 300 and 600 c but occasionally persisting to 675 c is directed shallowly southward or northward a mesoscale fold test at south sishen mine indicates that this component was acquired during deformation similarity of the direction to previous results suggests that it was acquired at 1240 ma during early namaqua orogenesis combining our int results with existing data from the namaqua eastern zone nez we calculate the nez pole at 44 9 n 021 5 e k 23 2 a 95 12 8 q 5 the most stable component from our data set hig always persisting as a nonzero endpoint to demagnetization at 665 680 c is observed in 32 samples from south sishen and beeshoek mines directed moderately east downward sishen or west upward beeshoek this component predates the mesoscale fold at sishen more importantly a conglomerate test at beeshoek indicates that hig was acquired prior to paleoproterozoic deposition of the gamagara mapedi formation the concordance between directions from the paleoweathering zone and immediately overlying red beds indicates that hig is a primary magnetic remanence for the basal gamagara mapedi bgm formation the dual polarity bgm paleomagnetic pole 02 2 n 081 9 e dp 7 2 dm 11 5 q 6 lies neatly between previous kaapvaal poles with ages of 2220 ongeluk lavas and 2060 ma bushveld complex our data thus support recent correlations of the gamagara mapedi formation with pre bushveld sediments of the pretoria group a pre bushveld age for bgm is also consistent with its substantial distance from a new albeit less reliable paleomagnetic pole from the 1930 ma hartley lavas higher within the olifantshoek succession 12 5 n 332 8 e k 18 6 a95 16 0 q 3 our conglomerate test at beeshoek confirms previous allegations that the intense hematitization observed in the drakenstein wolhaarkop paleosol occurred during paleoproterozoic weathering under a highly oxygenated atmosphere

geological geochemical and geochronological characteristics of weilasituo sn polymetal deposit inner mongolia china abstract the recently discovered weilasituo sn polymetal deposit is located in the southern part of the great xing an range of inner mongolia ne china which is belonged to the eastern part of the central asian orogenic belt caob sn polymetal mineralization is closely related to the emplacement of the early cretaceous fine to medium grained quartz porphyry three types of mineralization have been recognized at weilasituo with the disseminated and stockwork sn polymetal mineralization mainly hosted by the quartz porphyry the vein type sn polymetal mineralization hosted by ne trending and we trending fractures and faults in the upper and outer part of the porphyry and breccia mineralization occurred within a steep cryptoexplosive breccia pipe the ore related alteration typically consists of na ca sr alteration and greisen in order to understand the petrogenetic link between the sn polymetal mineralization and the host quartz porphyry this paper presents new whole rock geochemistry for the quartz porphyry epma analysis of ore and gangue minerals and in situ u pb dating of cassiterite the laser abrasion multiple collector inductively coupled plasma mass spectrometer la mcicp ms cassiterite u pb dating yields two well defined isochron ages of 138 6 ma for disseminated ore and 135 6 ma for the vein type ore which could be regarded as the ore forming age the cassiterite u pb ages ca 138 135 ma determined in this study together with previous data reveals the close temporal and genetic relationship between the mineralization event and the emplacement of the quartz porphyry the quartz porphyry is characterized by high sio2 na2o and a cnk values 1 09 1 21 ree tetrad effect combined with extremely high rb sr k ba ratios and low k rb zr hf la nb la ta and eu eu ratios indicate that the quartz porphyry is a highly fractionated peraluminous i type granite that is hydrothermally altered low end t values of 4 27 0 28 and the two stage depleted mantle nd model ages t2dm ca 1279 908 ma for the quartz porphyry are similar to granites in precambrian microcontinents of the eastern part of the central asian orogen caob this suggests that the quartz porphyry was derived from the remelting of juvenile crust and precambrian rocks in an extensional setting therefore the highly fractional crystallization and magmatic hydrothermal interactions of the quartz porphyry have contributed to the formation of the weilasituo sn polymetal deposit