mesozoic cenozoic tectonic evolution and metallogeny in myanmar evidence from zircon cassiterite u pb and molybdenite re os geochronology abstract it is well known that there are many sn w mo and cu au metal resources in myanmar however the absence of precise mineralization ages for these deposits significantly hinders to understand the close genetic relationship among metallogeny ore bearing intrusions and tectonic evolution in this study two groups of consistent molybdenite re os and zircon u pb ages indicate that the dapingba mo w deposit in northern myanmar tengchong terrane formed at early cretaceous 119 ma and 114 ma the dapingba ore bearing granitic magmas were mainly derived from melting of ancient tengchong crust on the basis of zircon hf isotopic compositions ehf t 9 3 to 2 5 moreover the first reported cassiterite u pb ages of 60 ma for the bawapin and kalonta sn w deposits in southern myanmar western sibumasu terrane suggest that the two deposits formed at paleocene whereas the precise molybdenite re os age for the shangalon porphyry cu au deposit in the west burma terrane indicates that this deposit formed at eocene 39 ma importantly combined with previous studies on tectonic evolution and magmatic petrogenesis in myanmar and southwest china a comprehensive mesozoic cenozoic tectono magmatic and metallogenic model are proposed two periods of early cretaceous 120 114 ma and late cretaceous 75 70 ma crust derived felsic melts and related mo sn w deposits from the tengchong and western sibumasu terranes likely formed in a continental arc during subduction of the meso and neo tethys oceanic lithosphere respectively subsequently paleocene eocene 60 50 ma sn w deposits and coeval ore bearing granites in the western sibumasu terrane possibly formed during roll back of the neo tethys oceanic slab after 50 ma india asia collision eocene 41 39 ma porphyry cu au west burma terrane and sn w deposits western sibumasu terrane likely formed during the neo tethys oceanic slab tear and break off in a collisional setting whereas miocene 19 14 ma high sulfidation epithermal cu deposit in the west burma terrane possibly formed in an arc setting during oblique subduction of the indian oceanic lithosphere

continuous h2o co2 222rn and temperature measurements on merapi volcano indonesia abstract a set of analytical instruments consisting of a gas chromatograph for water and carbon dioxide an alpha scintillation counter to measure radon and a temperature sensor was especially designed and constructed to monitor volcanic gases and was successfully operated over weeks in the high temperature fumaroles at the summit of merapi volcano indonesia the analytical unit runs automatically and is remote controlled through a radio link over a period of several weeks concentrations of h 2 o and co 2 were measured every 35 min and rn activity was monitored at about 90 min intervals the fumarole temperatures were continuously recorded every minute from july 2000 to the end of january 2001 the composition and temperature of the gas emitted at merapi volcano show significant variations due to a regular stronger degassing of the magma concentrations of co 2 increase periodically while h 2 o concentrations decrease on the other hand rn activity rises with increasing atmospheric pressure and higher water concentrations after intensive rainfall infiltration of cold meteoric water into the volcanic edifice possibly causes an increase in the concentration of water vapour and a decrease in the temperature of the gases in the fumarole several seismic events recorded at merapi correlate with gas temperature

continuous monitoring of fumarole temperatures at mount etna italy abstract in this paper we present the first data of temperature continuously recorded in two fumarole fields designated vor and hor located in the summit area of mount etna volcano italy the time series embraces two distinct periods 1 october 2007 to november 2009 during which an effusive eruption occurred from may 2008 to july 2009 and 2 november 2011 to june 2012 characterized by the occurrence of strong paroxysms fire fountains and lava flow the analysis of the temperature signal in both the time and frequency domains and its comparison with meteorological observations allowed us to separate the exogenous influences from the effects of variations in the activity state of the volcano the acquired data were weakly affected by seasonal cycles of the air temperature and strongly affected by the rainfall optimization of site conditions i e sensor depth and soil permeability markedly reduced meteorological disturbances the distance from the main degassing and or eruptive fractures was crucial to maximizing the probability of the technical survival of the monitoring apparatus which was seriously affected by the emission of acidic gases tephra fallout and lava flows apart from the exogenous influences the most appreciable variation was observed at vor where a huge increase in fumarole temperature was detected immediately after the onset of the 2008 2009 eruption such an anomalous increase was attributed to the rapid ascent of magma feeding the eruptive fracture another abrupt increase in temperature was recorded at hor in march and april 2012 during this period the frequency of paroxysm occurrence increased markedly and this led us to hypothesize that the thermal anomaly was due to the intrusion of a new batch of magma in the conduits of the southeast crater medium to long term monitoring weeks to months of fumarole temperatures revealed variations that were attributed to pressurization depressurization phases of the shallow volcanic system which varied between the various monitored sectors of the volcano our observations suggest that continuous monitoring of fumarole temperature can give useful information about the activity of mount etna moreover due to the complexity of its shallow plumbing system we conclude that the monitoring systems should be extended to cover the entire fumarole network of the summit area

fluid inclusion characteristics and geological significance of the xi ao copper tin polymetallic deposit in gejiu yunnan province abstract the newly discovered xi ao cu sn polymetallic deposit is located in the inner alteration zone of the laochang kafang granite edge in gejiu yunnan province the mineralization process of this deposit can be divided into four stages cassiterite and chalcopyrite mainly formed at stages ii and iii respectively fluid inclusions at different stages were studied by petrography microthermometry and laser raman spectrometry five fluid inclusion types are observed microthermometry results revealed that the ore forming fluid evolved from high temperature with low to intermediate salinity to low temperature with low salinity at stage i the fluid was under near critical conditions and then separated into coexisting liquid and vapor phases at stage ii finally the fluid was boiling and immiscible at stage iii a meteoric fluid mixing process was also observed at this stage laser raman spectra identified ch4 at the skarn and mineralization stages combined with other geological features the deposit was concluded to have formed under a relatively reduced environment the co2 component abruptly increased at stage iii and probably originated from the exterior fluorine may play an important role in mineralization cassiterite and chalcopyrite were mainly deposited at 340 440 and 300 400 c under pressures of 18 50 and 12 36 mpa respectively boiling and immiscibility are probably the main reason for mineral deposition the deposit of cassiterite and chalcopyrite showed similar salinities but higher temperatures than other mineralization types of deposits in the gejiu area this finding indicated that the study deposit probably represents the high temperature part of the gejiu mineralization system thereby benefiting mineral explorations in the gejiu area

u pb geochronology of calcite mineralized faults absolute timing of rift related fault events on the northeast atlantic margin constraining the timing of brittle faulting is critical in understanding crustal deformation and fluid flow but many regional scale fault systems lack readily available techniques to provide absolute chronological information calcite mineralization occurs in crustal faults in many geological settings and can be suitable for u pb geochronology this application has remained underutilized because traditional bulk dissolution techniques require uncommonly high u concentration because u and pb are distributed heterogeneously throughout calcite crystals high spatial resolution sampling techniques can target domains with high u and variable u pb ratios here we present a novel application of in situ laser ablation inductively coupled plasma mass spectrometry la icp ms to basaltic fault rock geochronology in the faroe islands northeast atlantic margin faults that are kinematically linked to deformation associated with continental break up were targeted acquired ages for fault events range from mid eocene to mid miocene and are therefore consistently younger than the regional early eocene onset of ocean spreading highlighting protracted brittle deformation within the newly developed continental margin calcite geochronology from la icp ms u pb analysis represents an important and novel method to constrain the absolute timing of fault and fluid flow events

volcanic ash hazard to aviation during the 2003 2004 eruptive activity of anatahan volcano commonwealth of the northern mariana islands abstract within the commonwealth of the northern mariana islands cnmi anatahan is one of nine active subaerial volcanoes that pose hazards to major air traffic routes from airborne volcanic ash the 2003 2004 eruptive activity of anatahan volcano affected the region s aviation operations for 3 days in may 2003 on the first day of the eruption 10 may 2003 two international flights from saipan to japan were cancelled and several flights implemented ash avoidance procedures on 13 may 2003 a high altitude flight through volcanic gas was reported with no perceptible damage to the aircraft toms and modis analysis of satellite data strongly suggests that no significant ash and only minor amounts of so 2 were involved in the incident consistent with crew observations on 23 may 2003 airport operations were disrupted when tropical cyclone winds dispersed ash to the south dusting saipan with light ashfall and causing flight cancellations there and at guam 320 km south of the volcano operational near real time monitoring of ash clouds produced by anatahan has been conducted since the first day of the eruption on 10 may 2003 by the washington volcanic ash advisory center vaac the vaac was among the first groups outside of the immediate area of the volcano to detect and report on the unexpected eruption of anatahan after being contacted about an unusual cloud by national weather service forecasters in guam at 1235 utc on 10 may 2003 the vaac analyzed goes 9 images confirming anatahan as the likely source of an ash cloud and estimating that the eruption began at about 0730 utc the vaac issued its first volcanic ash advisory for anatahan at 1300 utc on 10 may 2003 more than 5 h after the start of the eruption the delay reflecting the difficulty of detecting and confirming a surprise eruption at a remote volcano with no in situ real time geophysical monitoring the initial eruption plume reached 10 7 13 4 km 35 000 44 000 ft well into jet cruise altitudes thereafter the maximum plume height decreased and during the rest of the eruption usually did not exceed 5 km 17 000 ft which lessened the potential hazard to aircraft at higher cruise altitudes drifting ash clouds commonly extended hundreds of kilometers from the volcano occasionally as far west as the philippines over the course of the eruptive activity in 2003 2004 the vaac issued 323 advisories 168 with graphical depictions of ash clouds for anatahan serving as a reliable source of ash cloud information for aviation related meteorological offices and air carriers with a record of frequent eruptions in the cnmi continued satellite and in situ real time geophysical monitoring is needed at anatahan and other marianas volcanoes so that potential hazards to aviation from any future eruptive activity can be quickly and correctly assessed

evaluation of sulfur dioxide emissions from explosive volcanism the 1982 1983 eruptions of galunggung java indonesia abstract galunggung volcano java awoke from a 63 year quiescence in april 1982 and erupted sporadically through january 1983 during its most violent period from april to october the cikasasah volcano observatory reported 32 large and 56 moderate to small eruptions from april 5 through september 19 the total ozone mapping spectrometer toms carried on nasa s nimbus 7 satellite detected and measured 24 different sulfur dioxide clouds an estimated 1730 kilotons kt of so2 were outgassed by these explosive eruptions the trajectories and rapid dispersion rates of the so2 clouds were consistent with injection altitudes below the tropopause an additional 300 kt of so2 were estimated to have come from 64 smaller explosive eruptions based on the detection limit of the toms instrument for the first time an extended period of volcanic activity was monitored by remote sensing techniques which enabled observations of both the entire so2 clouds produced by large explosive eruptions using toms and the relatively lower levels of so2 emissions during non explosive outgassing using the correlation spectrometer or cospec based on cospec measurements from august 1982 to january 1983 and on the relationship between explosive and non explosive degassing approximately 400 kt of so2 were emitted during non explosive activity the total sulfur dioxide outgassed from galunggung volcano from april 1982 to january 1983 is calculated to be 2500 kt 30 from both explosive and non explosive activity while galunggung added large quantities of sulfur dioxide to the atmosphere its sporadic emissions occurred in relatively small events distributed over several months and reached relatively low altitudes and are unlikely to have significantly affected aerosol loading of the stratosphere in 1982 by volcanic activity

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

trace and rare earth element geochemistry in tourmaline and cassiterite from the yunlong tin deposit yunnan china implication for migmatitic hydrothermal fluid evolution and ore genesis abstract yunlong tin deposit is a medial sized hydrothermal deposit in western yunnan province of china this deposit is unusual because the tin mineralization occurs exclusively within the migmatite bodies the genesis of the ore deposit has been hotly debated and various models have been proposed including granite related magmatic hydrothermal and migmatitic hydrothermal origins this paper reports a systematic trace and rare earth elements ree geochemical study in tourmaline and cassiterite from the orebodies and associated migmatites from the yunlong tin deposit tourmaline and cassiterite from this deposit show light ree lree enriched patterns with variable eu and ce anomalies consistent with hydrothermal fluids being derived from local high grade metamorphism and migmatization the data suggest that tourmaline and cassiterite were likely precipitated from migmatitic hydrothermal fluids and indicate that the yunlong tin deposit was probably formed during migmatitic hydrothermal process the high concentrations of transition metals e g sc ti v cr mn and zn in tourmalines are also consistent with this model the high concentrations of sn sr and especially sc v and cr in tourmalines can be used to discriminate tourmaline from barren deposits relative to those associated with economic tin mineralization

variable so2 emission rates for anatahan volcano the commonwealth of the northern mariana islands implications for deriving arc wide volatile fluxes from erupting volcanoes 1 we report new spectroscopic derived so2 emission rates for anatahan volcano mariana islands measurements of so2 fluxes reveal large fluctuations over the 2003 2005 period from 78 kg s 1 which occurred on the same day as resurgent volcanic activity march 2005 to 50 kg s 1 and 25 kg s 1 made days weeks after the start of eruptive sequences in 2003 and 2004 respectively even the lowest values make anatahan a major global source of so2 over the past decade these so2 emission rates are used to estimate the co2 flux from the arc as a whole 3 6 40 107 mol km 1 yr 1 such values are significantly higher than estimates derived using other approaches they are also high compared to other convergent margins e g central america where the input flux of co2 is substantially greater our results caution against including volatile fluxes from actively degassing volcanoes to produce volatile outputs considered representative of entire arc fronts

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

the origin of the world class tin polymetallic deposits in the gejiu district sw china constraints from metal zoning characteristics and 40ar 39ar geochronology the gejiu tin polymetallic deposits in the western cathaysia block of south china comprise the world s largest primary tin district with a total resource of approximately 300 million metric ton ores at an average grade of 1 wt percent sn tin polymetallic mineralization occurs in five deposits and has four ore types i e greisen skarn stratabound cassiterite sulfide mostly oxidized and vein type ore in each deposit the orebodies typically occur in an extensive hydrothermal system centered on a shallow late cretaceous granitoid cupola metal zoning is well developed both vertically and horizontally over the entire district from w be bi mo sn ores inside granite intrusions to sn cu dominated ores at intrusion margins and farther out to pb zn deposits in the surrounding host carbonate this zoning pattern is similar to that of other hydrothermal deposits in other parts of the world indicating a close genetic relationship between magmatism and mineralization in this paper we dated thirteen mica samples from all types of mineralization and from the five deposits in the gejiu district the ages range from 77 4 0 6 ma to 95 3 0 7 ma and are similar to the existing zircon u pb age of the granitic intrusions 77 4 2 5 85 8 0 6 indicating a genetic relationship between the mineralization and the intrusions geological characteristics metal zoning patterns and new geochronological data all indicate that the tin polymetallic ores in the gejiu district are hydrothermal in origin and are genetically related to the nearby granitic intrusions it is unlikely that the deposits are syngenetic as has been proposed in recent years

multispectral thermal infrared mapping of sulfur dioxide plumes a case study from the east rift zone of kilauea volcano hawaii the synoptic perspective and rapid mode of data acquisition provided by remote sensing are well suited for the study of volcanic so2 plumes in this paper we describe a plume mapping procedure that is based on image data acquired with nasa s airborne thermal infrared multispectral scanner tims and apply the procedure to tims data collected over the east rift zone of kilauea volcano hawaii on september 30 1988 these image data covered the pu u o o and kupaianaha vents and a skylight in the lava tube that was draining the kupaianaha lava pond our estimate of the so2 emission rate from pu u o o 17 20 kg s 1 is roughly twice the average of estimates derived from correlation spectrometer cospec measurements collected 10 days prior to the tims overflight 10 kg s 1 the agreement between the tims and cospec results improves when we compare so2 burden estimates which are relatively independent of wind speed we demonstrate the feasibility of mapping pu u o o scale so2 plumes from space in anticipation of the 1998 launch of the advanced spaceborne thermal emission and reflectance radiometer aster

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

correlations between eruption magnitude so2 yield and surface cooling about the book humans have long marvelled at and feared the odorous and colourful manifestations of volcanic emissions and in some cases have harnessed them for their economic value the degassing process responsible for these phenomena is now understood to be one of the key factors influencing the timing and nature of volcanic eruptions moreover the surface emissions of these volatiles can have profound effects on the atmospheric and terrestrial environment and climate even more fundamental are the relationships between the history of planetary outgassing differentiation of the earth s interior chemistry of the atmosphere and hydrosphere and the origin and evolution of life this book provides a compilation of 23 papers that investigate the behaviour of volatiles in magma the feedbacks between degassing and magma dynamics and the composition flux and environmental atmospheric and climatic impacts of volcanic gas emissions

multi decadal satellite measurements of global volcanic degassing abstract satellite instruments have been providing measurements of global volcanic emissions of sulfur dioxide so 2 since 1978 based on observations in the ultraviolet uv infrared ir and microwave spectral bands we review recent advances in satellite remote sensing of volcanic gases focusing on increased instrument sensitivity to tropospheric so 2 emissions and techniques to determine volcanic plume altitude a synthesis of 36 years of global uv ir and microwave satellite measurements yields an updated assessment of the volcanic so 2 flux to the upper troposphere and lower stratosphere utls between 1978 and 2014 1 2 tg yr the present availability of multiple uv and ir satellite so 2 products provides increased confidence in calculated so 2 loadings for many eruptions we examine the temporal and latitudinal distribution of volcanic so 2 emissions and reassess the relationship between eruptive so 2 discharge and eruption magnitude finding a first order correlation between so 2 emission and volcanic explosivity index vei but with significant scatter based on the observed so 2 vei relation we estimate the fraction of eruptive so 2 emissions released by the smallest eruptions 0 48 tg yr which is not recorded by satellite observations a detailed breakdown of the sources of measured so 2 emissions reveals intuitively expected correlations between eruption frequency so 2 loading and volcanic degassing style we discuss new constraints on e folding times for so 2 removal in volcanic plumes and highlight recent measurements of volcanic hydrogen chloride hcl injections into the utls an analysis of passive volcanic emissions of so 2 detected in ozone monitoring instrument omi so 2 data since 2004 provides new insight into the location and stability of the dominant sources of volcanic so 2 over the past decade since volcanic so 2 emissions constitute a random highly variable perturbation to the atmosphere climate system continued monitoring of volcanic so 2 emissions from space by multiple uv and ir instruments to extend the current multi decadal record is essential and near global geostationary measurements of so 2 may be available by the end of the current decade

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

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

daily monitoring of ecuadorian volcanic degassing from space we present daily measurements of sulfur dioxide so2 emissions from active volcanoes in ecuador and southern colombia between september 2004 and september 2006 derived from the ozone monitoring instrument omi on nasa s eos aura satellite omi is an ultraviolet visible spectrometer with an unprecedented combination of spatial and spectral resolution and global coverage that permits daily measurements of passive volcanic degassing from space we use non interactive processing methods to automatically extract daily so2 burdens and information on so2 sources from the omi datastream maps of monthly average so2 vertical columns retrieved by omi over ecuador and s colombia are also used to illustrate variations in regional so2 loading and to pinpoint sources the dense concentration of active volcanoes in ecuador provides a stringent test of omi s ability to distinguish so2 from multiple emitting sources our analysis reveals that tungurahua reventador and galeras were responsible for the bulk of the so2 emissions in the region in the timeframe of our study with no significant so2 discharge detected from sangay at galeras and reventador we conclude that omi can detect variations in so2 release related to cycles of conduit sealing and degassing which are a critical factor in hazard assessment the omi so2 data for reventador are the most extensive sequence of degassing measurements available for this remote volcano which dominated regional so2 production in june august 2005 at tungurahua the omi measurements span the waning stage of one eruptive cycle and the beginning of another and we observe increasing so2 burdens in the months prior to explosive eruptions of the volcano in july and august 2006 cumulative so2 loadings measured by omi yield a total of 1 16 tg so2 emitted by volcanoes on mainland ecuador s colombia between september 2004 and september 2006 as much as 95 of this so2 may originate from non eruptive degassing approximate apportionment of the total so2 loading indicates that 40 originated from tungurahua with 30 supplied by both reventador and galeras these measurements of volcanic so2 degassing in ecuador confirm omi s potential as an effective economical and risk free tool for daily monitoring of so2 emissions from hazardous volcanoes

geochronology and geochemistry of the late cretaceous xinpeng granitic intrusion south china implication for sn w mineralization abstract large scale late cretaceous granitic intrusions are developed in the southernmost margin of south china block they constitute an ew trending magmatic rock and mineralization belt from guangdong to yunnan province some of these late cretaceous granitic intrusions are associated with sn w mineralization but the mineralization potential of other intrusions in this belt remains unclear due to intensive weathering and thick sediment covers the xinpeng intrusion is the largest late cretaceous granitic intrusion in the yangchun basin situated in guangdong province which mainly comprises of medium to coarse grained biotite granite previous geological surveys showed that the xinpeng intrusion has undergone extensive alteration stream sediments around the xinpeng intrusion displayed sn and w geochemical anomalies in addition greisen type and quartz vein type tin occurrences have been discovered in the xinpeng intrusion which preliminarily shows a certain mineralization potential of tin and tungsten however little information is known about the geochronological and geochemical characteristics of the xinpeng intrusion and this limits our further assessment of its sn w mineralization potential here we summarize the geochemical characteristics of late cretaceous ore forming granites in south china and report the geochronological and geochemical characteristics of the xinpeng granitic intrusion for the first time la icp ms zircon u pb dating yielded a weighted mean 206pb 238u age of 77 4 0 8 ma for the xinpeng granitic intrusion linking it with the late cretaceous magma activity the xinpeng intrusion is high k calc alkaline and slightly peraluminous chondrite normalized ree elements of the xinpeng intrusion show seagull like patterns with strong negative eu anomaly high rb sr ratios and low nb ta zr hf ratios indicate the xinpeng granitic intrusion experienced highly magmatic differentiation attributed to high volatile f contents that can dramatically reduce the viscosity and solidus of magma the intrusion shows whole rock initial sr isotope of 0 717703 0 718420 and nd isotope of 5 6 5 7 and zircon hf isotope of 3 28 0 62 indicating crust derived source with some input of mantle materials taking into account all the characteristics the xinpeng intrusion agrees well with the common geochemical characteristics of late cretaceous sn w bearing granites in the yangchun basin indicating that the xinpeng granitic intrusion has a great potential of sn w mineralization

u pb dating of perovskite by la icp ms an example from the oka carbonatite quebec canada abstract the potential for u pb dating of the mineral perovskite using laser ablation inductively coupled plasma mass spectrometry la icp ms has been evaluated perovskite can have relatively elevated u and th contents making it a potentially useful geochronometer kimberlite lamprophyre and carbonatite intrusions are prone to alteration and typically contain abundant xenocrysts thus standard techniques for dating the magmatic emplacement of these rocks becomes highly problematic perovskite however is commonly present as a primary magmatic mineral in these rocks and has been used to constrain the timing of kimberlite and lamprophyre emplacement the main limitations to the production of accurate la icp ms u pb ages for perovskite are the lack of suitable standards coupled with the large common pb correction required 204 hg can produce large isobaric interference on the non radiogenic 204 pb isotope and methods based on 208 pb 206 pb and u th ratios are hampered by the enhanced th content present in most perovskite crystals after careful calibration using zircon reference materials common pb corrected 206 pb 238 u ages can be determined on each individual la icp ms analysis by using the measured 207 pb 206 pb ratio which is dominated by the common pb proportion in phanerozoic rocks this method assumes that the perovskite crystals analyzed are cogenetic and have the same initial pb ratios the la icp ms method has been applied to data collected on two large single perovskite crystals from the oka carbonatite complex quebec canada the weighted mean 206 pb 238 u age of 131 7 ma n 25 mswd 0 42 is consistent with published geochronology data from the region and suggests that la icp ms dating of perovskite could be a useful low cost alternative to compliment existing techniques

trace and rare earth elements in cassiterite sources of components for the tin deposits of the mole granite australia trace and rare earth elements have been determined for cassiterite from deposits associated with the mole granite and hosted by granite metasediments and metavolcanics the ree of cassiterite is controlled by the ree of the the ore fluid and the rocks through which this fluid circulated the ree distribution factor and lree hree value of cassiterite is strongly influenced by the associated mineral assemblage the fluid chemistry and the crystal chemical characteristics of the host mineral cassiterite from deposits hosted by granite have trace and rare earth element characteristics similar to those determined for the mole granite cassiterite from deposits hosted by metasediments or acid volcanics have most trace and rare earth element characteristics similar to those of the enclosing rocks and some characteristics similar to the mole granite the ore fluid had chemical components derived from the parental granite and components acquired by passage through the metamorphosed aureole

indium in cassiterite and ores of tin deposits abstract the results obtained with la icp ms by less abundant lighter 113 in isotope and epma show that in cassiterite of cassiterite quartz veins the indium contents do not exceed 160 ppm while cassiterite from sn sulfide veins is characterized by higher indium contents from 40 to 485 ppm sulfides of sn sulfide veins unlike sulfides of cassiterite quartz veins also have the highest indium contents fe sphalerite 100 25 000 ppm chalcopyrite up to 1000 ppm and stannite up to 60 000 ppm indium contents in the sn sulfide ore of the tigrinoe and pravourmiiskoe deposits obtained using sr xrf icp ms and atomic absorption methods range from 10 to 433 ppm with average values of 56 65 ppm indium rich sn sulfide mineralization in five large sn ag ore districts of the far east russia khingansky badzhalsky komsomolsky arminsky kavalerovsky provides the impetus for further exploration of deposits with sn sulfide mineralization as the most promising indium resources in russia empirical observations from geology and geochronology of cassiterite quartz and sn sulfide mineralization show that the combined contribution from granite and alkaline subalkaline mafic sources and multistage ore forming processes doubled indium resources of deposits being the main factors in the formation of high grade indium mineralization

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

samarium neodymium direct dating of fluorite mineralization the direct dating of many styles of hydrothermal mineralization has proved difficult limiting understanding of the geological processes that lead to crustal fluid flow and the formation of major ore deposits the hydrothermal mineral fluorite caf2 displays large variations in rare earth element ree abundance and samarium neodymium ratios within a single vein samarium neodymium dating of fluorite from the classic granite hosted tin deposits of southwest england demonstrates its use as a precise chronometer of mineralization the concentrations of light rare earth elements lrees in the fluorites are highly variable and suggest the coeval precipitation of an lree rich phase as the most likely cause of the extreme variation in samarium neodymium ratios

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

u pb re os and 40ar 39ar geochronology of the nambija au skarn and pangui porphyry cu deposits ecuador implications for the jurassic metallogenic belt of the northern andes new u pb re os and 40ar 39ar dates are presented for magmatic and hydrothermal mineral phases in skarn and porphyry related ores from the nambija and pangui districts of the subandean zone southeastern ecuador nambija has been one of the main gold producing centers of ecuador since the 1980s due to exceptionally high grade ores average 15 g t but frequently up to 300 g t au pangui is a recently discovered porphyry cu mo district the geology of the subandean zone in southeastern ecuador is dominated by the i type subduction related jurassic zamora batholith which intrudes triassic volcanosedimentary rocks the zamora batholith is in turn cut by porphyritic stocks which are commonly associated with skarn formation and or porphyry style mineralization high precision u pb and re os ages for porphyritic stocks u pb zircon associated prograde skarn u pb hydrothermal titanite and retrograde stage skarn re os molybdenite from veins postdating gold deposition of the nambija district are all indistinguishable from each other within error 145 ma and indicate a late jurassic age for the gold mineralization previously gold mineralization at nambija was considered to be early tertiary based on k ar ages obtained on various hydrothermal minerals the new jurassic age for the nambija district is slightly younger than the 40ar 39ar and re os ages for magmatic hydrothermal minerals from the pangui district which range between 157 and 152 ma mineralization at nambija and pangui is associated with porphyritic stocks that represent the last known episodes of a long lived jurassic arc magmatism 190 to 145 ma a jurassic age for mineralization at nambija and pangui suggests that the northern andean jurassic metallogenic belt which starts in colombia at 3 n extends down to 5 s in ecuador it also adds a new mineralization style au skarn to the metal endowment of this belt

genesis of the oxidized sn ores in the gejiu district yunnan province sw china abstract the gejiu sn ore district one of the largest sn producing area 300mt 1 wt sn in the world is located in the western margin of the cathaysia block sw china there are five types of sn ores in the gejiu district including greisen skarn veined tourmaline massive sulfide and oxidized among these types of sn ores the genesis of the oxidized sn ores is most controversial such as magmatic hydrothermal origin and sedimentary exhalative sedex or hot water deposition red sea type this paper reports u pb ages fluid inclusions trace elements and h o isotopes of cassiterite from the oxidized sn ores aiming to solve this issue la mc icpms cassiterite u pb dating yielded an age of 86 7 2 8 ma which is accordant with the formation ages 86 ma of granitic intrusions in the gejiu district two types of fluid inclusions in cassiterite from the oxidized sn ores were observed one type is co2 rich inclusions type 1 and the other type is aqueous inclusions type 2 the homogenization temperatures range from 220 to 366 c and the salinities range from 10 9 to 21 wt nacl equiv for the two types of fluid inclusions furthermore fluid inclusions in cassiterite from the oxidized sn ores located at 300 m far away from granitic intrusions have higher temperatures 357 366 c than those located at 500 m 273 330 c hence the ore forming temperatures tend to decrease with the distance far away from the magmatic hydrothermal center the vapor components for the two types of fluid inclusions are co2 and h2o respectively and the liquid phase compositions of them are all h2o the co2 in the ore forming fluids may source from marble by decarbonization this indicates that the precipitation of cassiterite is resulted from fluid immiscible the 18o values of fluid inclusions in cassiterite range from 6 1 to 7 7 and the d values range from 135 to 153 indicating a mixture of magmatic and meteoric waters trace elements show that cassiterite is rich in in rb and u but ba nb and ti are depleted in addition the lower sr 0 4 2 1 ppm and higher sc 35 9 53 7 ppm contents reflect that the formation of cassiterite is related to f rich intermediate acid magma cassiterite has a relatively low total ree contents 2 7 9 2 ppm with negative eu eu 0 14 0 76 and ce ce 0 1 0 6 anomalies indicating that the ore forming environment is oxidized this is consistent with the cassiterite precipitation conditions hence all the evidence supports that the oxidized sn ores are genetically associated with the gejiu granitic magmatism

samarium neodymium isotope systematics of hydrothermal calcites from the xikuangshan antimony deposit hunan china the potential of calcite as a geochronometer abstract the xikuangshan antimony mine located at central hunan china is the largest antimony deposit in the world hydrothermal calcites from the xikuangshan mine display relatively large variations in ree abundance and sm nd ratios and are characterized by mree and hree enriched and lree depleted patterns sm nd isotopic compositions of syn sulfide calcites fall on well defined lines in the isochron plot calcites from early and late stage mineralization form two distinct isochrons corresponding to 155 5 1 1 and 124 1 3 7 ma respectively the isochron ages suggest that sb mineralization took place during the late jurassic early cretaceous period in the xikuangshan district consistent with previous geological observations and with independent isotope data samarium neodymium dating of calcites shows potential for determining ages of hydrothermal mineralization

the relationship between degassing and ground deformation at soufriere hills volcano montserrat we examine the correlations between so2 emission rate seismicity and ground deformation in the month prior to the 25 june 1997 dome collapse of the soufriere hills volcano montserrat during this period the volcano exhibited a pattern of cyclic inflation and deflation with an 8 14 h period we find that so 2 emission rates measured by cospec correlate with the amplitude of these tilt cycles and that higher rates of so 2 emission were associated with stronger ground deformation and enhanced hybrid seismicity within tilt cycles degassing peaks coincide with maximum deformation gradients increases in the amount of gas in the magma conduit feeding the dome probably due to increases in volatile content of ascending magma volume can account for the observed increases in tilt amplitude hybrid seismicity and so2 emission rate q 2000 elsevier science b v all rights reserved

transcurrent faulting and the anomalous position of pre carboniferous anglesey the marked differences of pre carboniferous geology between anglesey and of mainland north wales are accouonted for by devonian transcurrent faulting probably caused by stresses resulting from the closure of the lapetus ocean displacement along this fault is thought to have exceeded 100 km so that the lake district and not anglesey would formerly have been in juxtaposition with north wales

gas and particle emissions from soufriere hills volcano montserrat west indies characterization and health hazard assessment the soufriere hills volcano montserrat erupting since 18 july 1995 intensified its degassing in early 1996 with the continuing growth of the lava dome inside the summit crater during this period of increased activity between 11 and 18 march 1996 we measured gases and particles within the visible plume to determine whether at that time it posed a health risk to the population of plymouth the capital town which is 5 km southwest downwind and was then still occupied gravimetric measurements were made of total suspended particles tsp and particles having an aerodynamic diameter of less than 10 m pm10 measurements were made of sulphur dioxide so2 hydrochloric acid hcl hydrofluoric acid hf nitric acid hno3 acetic acid ch3cooh formic acid hcooh and particulate sulphate so4 2 chloride cl nitrate no3 fluoride f methanesulphonate ch3so3 acetate ch3coo formate hcoo ammonium nh4 sodium na and acidity h trace metals having human health implications chromium cr nickel ni cobalt co copper cu zinc zn arsenic as selenium se cadmium cd tin sn mercury hg and lead pb were also determined mean concentrations of hcl so2 and hf obtained in the town of plymouth were 14 0 5 9 and 0 8 ppbv respectively corresponding concentrations in the mixed plume on the crater edge were 533 168 and 22 ppbv there were no direct emissions of hno3 although nitrate was detected in coarse particles at the source higher concentrations of ch3cooh and hcooh were measured close to the crater mean tsp and pm10 were 64 and 15 g m 3 in plymouth and 455 and 47 g m 3 on the upper volcano slope aerosols were highly acidic at the source but rapidly neutralised during transport trace metals were enriched in the aerosol relative to crater surface material the concentrations of the acid gases sulphur dioxide in particular and particles were found to be too small to pose a health hazard at the time of these measurements when relatively modest volcanic activity was occurring

u pb columbite tantalite chronology of rare element pegmatites using tims and laser ablation multi collector icp ms u pb isotopic analyses using tims and laser ablation multi collector icp ms were carried out on columbite tantalite minerals from three suites of rare element li cs ta pegmatites in the superior province of canada conventional tims analyses of these columbite tantalite crystals produce scattered data and reverse discordance even after hf leaching of the grains prior to dissolution possibly reflecting the incomplete removal of the open system metamict segments during sample preparation la mc icp ms analyses of unleached primary columbite free from inclusions and alteration give consistent and precise 0 5 pb pb ages demonstrating the utility of this approach however normal and reverse discordance is also observed in u pb data from la mc icp ms analyses this discordance represents either u pb mobilisation during recent weathering sample preparation and or an analytical artefact originating from variable elemental fractionation between u and pb during ablation and ionisation that itself may have its origin in the contrasting metamictization of the dated columbite and the monazite standard used best age estimates of columbite from pegmatites in the superior province are 2670 5 ma for the pakeagama lake pegmatite 2644 7 ma for the separation rapids group and 2665 8 ma for the mavis lake group the ages broadly show that the rare element pegmatites are temporally synchronous with adjacent peraluminous granites

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

satellite measurement of sulfur dioxide from the redoubt eruptions of 1989 1990 abstract the mass of so 2 emitted by the 16 major explosive eruptions of redoubt volcano between december 1989 and april 1990 have been examined by the total ozone mapping spectrometer toms carried on the nimbus 7 satellite because of low light levels during the winter months toms could not detect so 2 at high northern latitudes thus the major eruptions from december through february could not be monitored unless winds brought the clouds to latitudes lower than about 58 n only two so 2 clouds were observed in the satellite data an approximately 100 kiloton kt cloud on december 16 over nevada and eastern california and a 10 kt cloud on march 9 directly over the volcano we speculate that the major eruption on december 15 at 1015 hour produced the 100 kt cloud seen on december 16 and the mass of so 2 injected into the atmosphere at that time was 175 50 kt

source strength assessment of volcanic trace elements emitted from the indonesian arc abstract we have for the first time estimated volcanic emission of volatile metals for a large regional volcanic source showing permanent activity namely the indonesian arc we have done this by normalizing concentrations of metals ratios in volcanic plumes to so 2 emission rates metal so 2 ratios measured in magmatic gases are used to estimate emissions from eruptive activity whereas those measured in fumarolic gases are used to estimate emissions from non eruptive activity the so 2 emission rate obtained is 3 5 10 6 tons per year which represents about 20 of the annual worldwide volcanic flux of so 2 the obtained trace metal 210 po pb bi cd zn and cu fluxes account for only about 5 to 30 of their global volcanic flux these relatively low values for trace metal emissions relative to the volcanic activity and the number of active volcanoes of the region appear to reflect the andesitic magma composition of the volcanoes of the arc

early evolution of a stratospheric volcanic eruption cloud as observed with toms and avhrr this paper is a detailed study of remote sensing data from the total ozone mapping spectrometer toms and the advanced very high resolution radiometer avhrr satellite detectors of the 1982 eruption of el chichon mexico the volcanic cloud atmosphere interactions in the first four days of this eruption were investigated by combining ultraviolet retrievals to estimate the mass of sulfur dioxide in the volcanic cloud krueger et al 1995 with thermal infrared retrievals of the size optical depth and mass of fine grained 1 10 m radius volcanic ash wen and rose 1994 our study provides the first direct evidence of gravitational separation of ash from a stratospheric gas rich plinian eruption column and documents the marked differences in residence times of volcanic ash and sulfur dioxide in volcanic clouds the eruption column reached as high as 32 km carey and sigurdsson 1986 and was injected into an atmosphere with a strong wind shear which allowed for an observation of the separation of sulfur dioxide and volcanic ash the upper more sulfur dioxide rich part of the cloud was transported to the west in the stratosphere while the fine grained ash traveled to the south in the troposphere the mass of sulfur dioxide released was estimated at 7 1 109 kg with the mass decreasing by approximately 4 1 day after the peak the mass of fine grained volcanic ash detected was estimated at 6 5 109 kg amounting to about 0 7 of the estimated mass of the ash which fell out in the mapped ash blanket close to the volcano over the following days 98 of this remaining fine ash was removed from the volcanic cloud and the effective radius of ash in the volcanic cloud decreased from about 8 m to about 4 m

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

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

laser ablation icp ms titanite u th pb dating of hydrothermal ore deposits a case study of the tonglushan cu fe au skarn deposit se hubei province china abstract titanite from the tonglushan cu fe au skarn deposit daye district eastern china has been successfully dated by laser ablation inductively coupled plasma mass spectrometry la icp ms hydrothermal titanite from both skarn ores and calcite veins cutting the ore bodies are characterized by having much lower ree and th u and lu hf ratios compared to their magmatic equivalents from the ore related yangxin quartz diorite intrusion and a late stage albitite dike titanite from the yangxin quartz diorite and an albitite dike which intrudes both the quartz diorite intrusion and ore bodies yield weighted mean 206pb 238u ages of 136 0 1 5 ma and 120 6 2 3 ma 2 respectively in agreement within analytical uncertainty to their 208pb 232th ages in situ analysis of epidote enclosed hydrothermal titanite in thin sections of a skarn ore sample yields a mean 206pb 238u age of 135 9 1 3 ma and 208pb 232th age of 138 2 4 5 ma whereas titanite in calcite from a calcite dominated vein cross cutting the skarn ore body has consistent 206pb 238u and 208pb 232th ages of ca 121 ma the data thus reveal two independent hydrothermal events the earlier event was responsible for the known cu fe au skarn mineralization at tonglushan and throughout the daye district and was caused by coeval magmatism that has resulted in the emplacement of the yangxin quartz diorite the later event previously unrecognized was associated with a second magmatic pulse as represented by the albitite dikes and provides potential for discovering new mineral deposits at tonglushan and possibly over the daye district this study represents the first direct dating of skarn deposits using titanite u th pb geochronometer and signifies the utilization of titanite for precise dating of hydrothermal ore formation

micro characterisation of cassiterite by geology texture and zonation a case study of the karagwe ankole belt rwanda abstract field geology petrography and texturally controlled compositional studies were carried out on cassiterite from the karagwe ankole belt kab in rwanda to understand the tin sn ore formation and cassiterite chemistry it is identified that muscovite rich veins are potentially sn bearing indicating that acid neutralising muscovitisation reactions were part of mechanisms for the sn precipitation as a result of fluid rock interaction pleochroism and light to dark brown colour zonation of cassiterite relates to compositional variation of elements substituting for sn dark brown zones are enriched in nb ta ti and fe relative to the lighter zones which approach pure greater than 99 sno2 x ray elemental maps show that elevated nb and ta concentrations are more correlated with darker brown cassiterite than are ti and fe intra grain compositional analysis shows that the internal textures of cassiterite are also defined by trace element distribution with an enrichment of ta nb fe v al and u in darker cathodoluminescence cl bands relative to lighter bands one or more of these elements may be quenching the cl whereas ti and w may activate the cl these elements are incorporated within cassiterite via the substitution 2 n n b t a v 5 1 n f e m n c a m g 2 n al s c f e 3 3 n s n 4 w h e r e 0 n 1 ti along with other tetravalent elements zr hf u w is incorporated in cassiterite by direct substitution ti4 sn4 the presence of small randomly disseminated rutile inclusions in cassiterite is attributed to the isostructural nature of these two minerals enrichment of ta and nb in the cassiterite formed in high temperature environments reveals the potential of cassiterite as an additional resource for these critical metals

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

the geochemistry and origins of the precambrian rocks of the rosslare complex se ireland geochemical studies of gneisses from the rosslare complex have indicated that the grey gneisses comprise a suite of sediments consisting mainly of greywackes before metamorphism these were associated with tholeiitic gabbros which are now represented by the greenore diorite and early granodiorites during migmatization after this early high amphibolite facies metamorphic event the st helen9s gabbro was intruded subsequently tholeiitic older basic dykes were also emplaced a low amphibolite facies metamorphic event accompanied by localized alkali metasomatism modified the chemistry and mineralogy of these basic intrusive rocks finally tholeiitic younger basic dykes which have subsequently been altered or mildly metamorphosed were emplaced before the complete crystallization of the ordovician saltees granite

constraints on cooling and degassing of pumice during plinian volcanic eruptions based on model calculations during explosive volcanic eruptions pumice clasts are transported into the atmosphere and their thermal and degassing histories determine how much volatiles are lost syneruptively this process is studied by combining a steady state eruption column model with a model for the cooling and degassing of pumice in the model we investigate the impact of various parameters e g mass eruption rate biot number eruption temperature and geometry on the cooling and degassing of pumice and find that the biot number and the eruption temperature are the most influential during typical risetimes of pumices inside eruption columns 200 300 s those smaller than 0 5 cm in diameter are found to lose little of their volatiles syneruptively and remain in thermal equilibrium with the plume in the case of larger pumices the ratio of the cooling timescale r p 2 where rp is the pumice radius and is the thermal diffusivity to the degassing timescale w 2 d 0 where w is the vesicle wall thickness and d 0 is the species diffusivity controls degassing if this ratio is larger than 50 degassing of the pumice will be nearly complete with a few percent of the original volatiles left in the outer rind of the pumice for a ratio of less than 0 1 no volatiles escape the pumice typical values for thermal and species diffusivity as well as vesicle wall thickness indicate that in the case of degassing cl and h 2 o the transition from 0 1 to 50 will be in the pumice size range of 1 10 cm here volatile concentration is a strong function of position inside the pumice suggesting that values for volatile contents measured on picked matrix glass from crushed samples may not be the best way to estimate the volatile content of matrix glass a number which is frequently used to estimate the total volatile input of volcanic eruptions this effect is even more pronounced when looking at hydrogen isotopic fractionation with larger pumices tending toward d 80

particles in the great pinatubo volcanic cloud of june 1991 the role of ice 1 pinatubo s 15 june 1991 eruption was earth s largest of the last 25 years and it formed a substantial volcanic cloud we present results of analysis of satellite based infrared remote sensing using advanced very high resolution radiometer avhrr and tiros operational vertical sounder high resolution infrared radiation sounder 2 tovs hirs 2 sensors during the first few days of atmospheric residence of the pinatubo volcanic cloud as it drifted from the philippines toward africa an so2 rich upper 25 km portion drifted westward slightly faster than an ash rich lower 22 km part though uncertainty exists due to difficulty in precisely locating the ash cloud the pinatubo clouds contained particles of ice ash and sulfate which could be sensed with infrared satellite data multispectral ir data from hirs 2 were most useful for sensing the pinatubo clouds because substantial amounts of both ice and ash were present ice and ash particles had peak masses of about 80 and 50 mt respectively within the first day of atmospheric residence and declined very rapidly to values that were 10 mt within 3 days ice and ash declined at a similar rate and it seems likely that ice and ash formed mixed aggregates which enhanced fallout sulfate particles were detected in the volcanic cloud by ir satellites very soon after eruption and their masses increased systematically at a rate consistent with their formation from so2 which was slowly decreasing in mass during the same period the initially detected sulfate mass was 4 mt equivalent to 3 mt so2 and after 5 days was 12 16 mt equivalent to 9 12 mt so2

emission rates of sulfur dioxide and carbon dioxide from redoubt volcano alaska during the 1989 1990 eruptions airborne measurements of sulfur dioxide emission rates in the gas plume emitted from fumaroles in the summit crater of redoubt volcano were started on march 20 1990 using the cospec method during the latter half of the period of intermittent dome growth and destruction between march 20 and mid june 1990 sulfur dioxide emission rates ranged from approximately 1250 to 5850 t d rates notably higher than for other convergent plate boundary volcanoes during periods of active dome growth emission rates following the end of dome growth from late june 1990 through may 1991 decreased steadily to less than 75 t d the largest mass of sulfur dioxide was released during the period of explosive vent clearing when explosive degassing on december 14 15 injected at least 175 000 50 000 tonnes of so2 into the atmosphere following the explosive eruptions of december 1989 redoubt volcano entered a period of intermittent dome growth from late december 1989 to mid june 1990 during which redoubt emitted a total mass of so2 ranging from 572 000 90 000 tonnes to 680 000 90 000 tonnes from mid june 1990 through may 1991 the volcano was in a state of posteruption degassing into the troposphere producing approximately 183 000 50 000 tonnes of so2 we estimate that redoubt volcano released a minimum mass of sulfur dioxide of approximately 930 000 tonnes while cospec data were not obtained frequently enough to enable their use in eruption prediction so2 emission rates clearly indicated a consistent decline in emission rates between march through october 1990 and a continued low level of emission rates through the first half of 1991 values from consecutive daily measurements of sulfur dioxide emission rates spanning the march 23 1990 eruption decreased in the three days prior to eruption that decrease was coincident with a several fold increase in the frequency of shallow seismic events suggesting partial sealing of the magma conduit to gas loss that resulted in pressurization of the shallow magma system and an increase in earthquake activity unlike the short term so2 decrease in march 1990 the long term decrease of sulfur dioxide emission rates from march 1990 through may 1991 was coincident with low rates of seismic energy release and was interpreted to reflect gradual depressurization of the shallow magma reservoir the long term declines in seismic energy release and in so2 emission rates led avo scientists to conclude on april 19 1991 that the potential for further eruptive activity from redoubt volcano had diminished and on this basis the level of concern color code for the volcano was changed from code yellow volcano is restless earthquake activity is elevated activity may include extrusion of lava to code green volcano is in its normal dormant state

geology and genesis of kafang cu sn deposit gejiu district sw china kafang is one of the main ore deposits in the world class gejiu polymetallic tin district sw china there are three main mineralization types in the kafang deposit i e skarn cu sn ores stratiform cu ores hosted by basalt and stratiform cu sn ores hosted by carbonate the skarn mainly consists of garnet and pyroxene and retrograde altered rocks these retrograde altered rocks are superimposed on the skarn and are composed of actinolite chlorite epidote and phlogopite major ore minerals are chalcopyrite pyrrhotite cassiterite pyrite and scheelite sulfur and pb isotopic components hint that the sources of different types of mineralization are distinctive and indicate that the skarn ore mainly originated from granitic magma whereas the basalt hosted cu ores mainly derived from basalt microthermometry results of fluid inclusions display a gradual change during the ore forming process the homogenization temperature of different types of inclusions continuously decreases from early to late mineralization stages the salinities and freezing temperatures exhibit similar evolutionary tendencies with the t homogenizaion while the densities of the different types keep constant the majority being less than 1 oxygen and hydrogen isotopic values o and d of the hydrothermal fluids fall within ranges of 3 1 to 7 7 with an average of 6 15 calculated at the corresponding homogenization temperature and 73 and 98 with an average of 86 5 respectively microthermometry data and h o isotopes indicate that the ore forming fluid of the kafang deposit is mainly derived from magma in the early stage and a mixture of meteoric and magmatic water in late stage molybdenite re os age of the skarn type mineralization is 83 4 2 1 ma and the stratiform ores hosted by basalt is 84 2 7 3 ma which are consistent with the la icp ms zircon age of the xinshan granite intrusion 83 1 0 4 ma the evidence listed above reflects the fact that different ore styles in the kafang deposit belong to the same mineralization system

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

age and granite association of skarn w mineralization at niutangjie district south china block abstract numerous w sn deposits are developed in the south china block with the majority related to the yanshanian jurassic to cretaceous granites a smaller number of deposits have been found associated with kwangsian middle paleozoic granites the largest of which is the niutangjie skarn w deposit the niutangjie deposit is spatially associated with two suites of granites the unmineralized yuechengling biotite and two mica granites have zircon u pb ages of 427 1 2 9 ma and 427 5 3 5 ma respectively whereas the mineralized niutangjie muscovite granite yields a younger age of 421 0 1 5 ma u pb dating of cassiterite coexisting with scheelite from the niutangjie muscovite granite indicates a mineralization age of 420 8 8 0 ma consistent with the age of the host rock the unmineralized yuechengling biotite granites have a cnk ratios of 0 97 1 16 and show characteristics of both i type and s type granites in contrast the mineralized niutangjie muscovite granites are s type granites with a cnk ratios of 1 12 1 72 and have higher sio2 contents and rb sr ratios and lower nb ta zr hf and k rb ratios than the unmineralized yuechengling biotite granites geochemical differences together with zircon hf isotopic compositions indicate that the relatively fractionated mineralized niutangjie muscovite granites were generated by partial melting of proterozoic meta sediments whereas the unmineralized yuechengling biotite granites were derived from partial melting of proterozoic meta sediments with subordinate meta igneous rocks the unmineralized yuechengling two mica granites have similar geochemical characteristics to the mineralized niutangjie muscovite granites but their relatively small volumes and lack of exploration may explain why the yuechengling two mica granites have not so far been found to be mineralized similarly the larger volume and more highly fractionated nature of the mesozoic yanshanian mineralized granites may explain the greater abundance of w sn mineralization associated with these rocks compared to the paleozoic kwangsian granites

re evaluation of so2 release of the 15 june 1991 pinatubo eruption using ultraviolet and infrared satellite sensors 1 in this study ultraviolet toms total ozone mapping spectrometer satellite data for so2 are re evaluated for the first 15 days following the 15 june 1991 pinatubo eruption to reflect new data retrieval and reduction methods infrared satellite so2 data from the tovs hirs 2 tiros television infrared observation satellite optical vertical sounder high resolution infrared radiation sounder 2 sensor whose data sets have a higher temporal resolution are also analyzed for the first time for pinatubo extrapolation of so2 masses calculated from toms and tovs satellite measurements 19 118 hours after the eruption suggest initial so2 releases of 15 3 mt for toms and 19 4 mt for tovs including so2 sequestered by ice in the early pinatubo cloud tovs estimates are higher in part because of the effects of early formed sulfate the toms so2 method is not sensitive to sulfate but can be corrected for the existence of this additional emitted sulfur the mass of early formed sulfate in the pinatubo cloud can be estimated with infrared remote sensing at about 4 mt equivalent to 3 mt so2 thus the total s release by pinatubo calculated as so2 is 18 4 mt based on toms and 19 4 mt based on tovs the so2 removal from the volcanic cloud during 19 374 hours of atmospheric residence describes overall e folding times of 25 5 days for toms and 23 5 days for tovs these removal rates are faster in the first 118 hours after eruption when ice and ash catalyze the reaction and then slow after heavy ash and ice fallout so2 mass increases in the volcanic cloud are observed by both toms and tovs during the first 70 hours after eruption most probably caused by the gas phase so2 release from sublimating stratospheric ice ash gas mixtures this result suggests that ice sequestered so2 exists in all tropical volcanic clouds and at least partially explains so2 mass increases observed in other volcanic clouds in the first day or two after eruption