zircon u pb geochronology geochemistry and s pb isotopic compositions of the lietinggang iron polymetallic deposit tibet china abstract the lietinggang deposit is a representative skarn iron polymetallic deposit in the nyainqentanglha skarn polymetallic zone nsp in lhasa terrane tibet the mineralization is hosted in skarn of the early and middle triassic chaqupu formation plutons in the deposit include gabbro diorites divided into the d1 and d2 diorites granodiorite syenogranite and porphyritic granite and the d2 diorite and syenogranite are the mineralization associated plutons in this study we present la icp ms zircon u pb dating zircon hf isotopic and whole rock geochemical data of the diorites and porphyritic granite and s pb isotopic compositions of the ore sulfides in the lietinggang deposit zircon u pb dating results for these intrusions yield paleocene ages of 62 2 59 0 ma all the intermediate and felsic intrusions are i type and characterized by arc magma geochemical features enriched in lree and lile well developed negative eu anomalies and depletion in hfse with most having positive ehf t values these geochemical characteristics are similar with the coeval intrusions of the gangdese batholith and linzizong group volcanic rocks indicating they share a similar magma source this magma source is proposed to be partial melting of the young metasomatized asthenospheric mantle wedge derived basaltic rocks during the magma evolution the fractionated crystallization has also play an important role 34s values for sulfides have features of magma source the 206pb 204pb 18 043 18 711 207pb 204pb 15 520 15 776 and 208pb 204pb 38 288 39 215 values of sulfides show that ore forming metals were derived from mixing sources of mantle with upper crust materials geochemical characteristics of the intermediate and felsic intrusions combined with the dating results indicate that the lietinggang magmatism and mineralization were formed within the india asia continental collision tectonic setting

epithermal mineralization and ore controls of the shasta au ag deposit toodoggone district british columbia canada the shasta gold silver deposit british columbia canada is an adularia sericite type epithermal deposit in which deposition of precious metals coincided with the transition of quartz to calcite dominant gangue mineralization is associated with stockwork breccia zones in potassically altered dacitic lapilli tuffs and flows and consists of pyrite sphalerite chalcopyrite galena acanthite electrum and native silver pre and post ore veins consist solely of quartz and calcite respectively fluid inclusion microthermometry indicates that ore minerals were deposited between 280 and 225 c from a relatively dilute hydrothermal fluid 1 5 wt nacl equivalent abundant vapor rich inclusions in ore stage calcite are consistent with boiling oxygen and hydrogen isotopic data 18ofluid 1 5 to 4 1 dfluid 148 to 171 suggest that the fluid had a meteoric origin but was 18o enriched by interaction with volcanic wallrocks initial 280 c fluid ph and log f o2 conditions are estimated at 5 3 to 6 0 and 32 5 to 33 bar respectively during ore deposition the fluid became more alkaline and oxidizing ore deposition at shasta is attributed to localization of meteoric hydrothermal fluids by extensional faults mineralization was controlled by boiling in response to hydraulic brecciation calcite and base metal sulfides precipitated due to the increase in ph that accompanied boiling and the associated decrease in h2s concentration led to precipitation of gold and silver

microgranular enclaves in island arc andesites a possible link between known epithermal au and potential porphyry cu au deposits in the tulasu ore cluster western tianshan xinjiang china abstract the successful exploration for porphyry copper deposit in western tianshan xinjiang faces great challenge tulasu basin is an important epithermal gold ore cluster in western tianshan which was formed in a southwest pacific type island arc setting during the late paleozoic by the southward subduction of the north tianshan ocean beneath the yili plate porphyry cu au deposits are possibly to be found at depth or adjacent to these epithermal gold deposits some sulfide mineralized microgranular enclaves of monzonite porphyry and microdiorite were found in andesites of the tawuerbieke gold district tulasu basin the enclaves are randomly distributed with generally round or subangular shape and commonly clearly defined within their host andesite and have a chilled surrounding margin of andesite the monzonite porphyry enclaves mpe exhibit porphyritic texture with the phenocrysts of plagioclase and k feldspar the microdiorite enclaves mde are mainly composed of plagioclase and hornblende with an aplitic texture and massive structure the host andesites show porphyritic texture with the phenocrysts major of plagioclase minor of hornblende and clinopyroxene the groundmass consists of short column plagioclase and minor clinopyroxene with a hyalopilitic texture zircon grains from a mpe sample yield a weighted 206pb 238u age of 356 2 4 3 ma n 13 mswd 1 11 which is effectively coincident with the 360 5 3 4 ma n 20 mswd 0 61 of an andesite sample within analytical error indicating that they were coeval in addition the mpe mde and the andesite samples share similar normalized incompatible element and rare earth element patterns that are characterized by a pronounced enrichment of large ion lithophile elements and a deficit of high field strength elements moreover the samples show similar nd isotope compositions to the contemporary andesites and basaltic andesites detailed petrology geochronology and geochemistry studies suggest that these enclaves were captured from an underlying body during the eruption of island arc magma thus unmapped cognate porphyry intrusions associated with cu au mineralization may exist under the andesite strata this evidence in combination with the low and high sulfidation epithermal gold deposits acidic hydrothermal alterations and copper mineralization evidence suggests that a porphyry epithermal cu au metallogenic system might occur in the tulasu basin of western tianshan and that the tawuerbieke district should be an important target for porphyry cu au exploration

magmatic and structural controls on porphyry style cu au mo mineralization at kemess south toodoggone district of british columbia canada kemess south is the only cu au mo mine in the toodoggone district and a major cu and au producer in british columbia porphyry style cu au mo mineralization is mainly hosted by the tabular sw plunging 199 6 0 6 ma maple leaf granodiorite which intrudes tightly folded sw dipping permian asitka group siltstone and limestone and homogeneous triassic takla group basalt southwest dipping 194 0 0 4 ma toodoggone formation conglomerate volcaniclastic and epiclastic rocks overlie the granodiorite and asitka group rocks minor cu au mo mineralization is hosted by the immediate takla group basalt country rock whereas low tonnage high grade cu zones occur beneath a 30 m thick leached capping in supergene altered granodiorite and in exotic positions in overlying toodoggone formation conglomerate granodiorite has an intrusive contact with mineralized and altered takla group basalt but displays a sheared contact with unmineralized and less altered asitka group siltstone the north block fault is a deposit scale e striking steeply s dipping normal fault that juxtaposes the granodiorite basalt ore body against unmineralized asitka group rocks younger nw and ne striking normal dextral faults cut all rock types orebodies and the north block fault with displacements of up to 100 m and result in the graben and horst style block faulting of the stratigraphy and ore body both basalt and granodiorite host comparable vein sequence and alteration histories with minor variations in hydrothermal mineral assemblages caused by differing protolith chemistry early potassic alteration and associated early stage cu au mo mineralization is partly replaced by phyllic and intermediate argillic alteration associated with main stage cu au mo mineralization two main stage veins have re os molybdenite ages of 201 3 1 2 and 201 1 1 2 ma these mineralization ages overlap the 199 6 0 6 ma u pb zircon crystallization age for the maple leaf granodiorite late stage pyrite rich stringer veins and related phyllic alteration assemblages are cut by anhydrite rich carbonate rich and chlorite veins fluids and metals associated with early main and late stage veins were probably derived principally from the same deep magma chamber as the maple leaf granodiorite these magmatic derived fluids interacted with asitka and takla group country rocks and possibly with meteoric and metamorphic fluids prior to mineralization

cenozoic high k alkaline magmatism and associated cu mo au mineralization in the jinping fan si pan region southeastern ailao shan red river shear zone southwestern china northwestern vietnam abstract the jinping fan si pan jfp cenozoic magmatic and cu mo au metallogenic belt in the southeastern part of the ailao shan shear zone host the tongchang chang an habo and chinh sang cu mo au deposits these deposits form an integrated epithermal porphyry regional mineralization system associated with 40 32 ma high k alkaline magmatism the magmatic rocks in the belt have relatively low tio2

an ice core indicator of antarctic sea ice production 1 the sea ice surface not open water is the dominant source of sea salt to aerosol and ice cores in coastal antarctica here we show that it may also form the dominant source for central antarctica we can then explain higher concentrations in the winter and last glacial maximum lgm as being due to increased sea ice production this suggests that ice core sea salt can indicate at least the timing of changes in antarctic sea ice production the pattern of sea salt in ice cores is consistent with marine evidence about sea ice changes in the holocene and lgm sea salt shows no change at the initial co2 increase out of the last glacial making it unlikely this was primarily due to changing sea ice cover the sea salt record should not be treated as an indicator of meridional transport

major features and forcing of high latitude northern hemisphere atmospheric circulation using a 110 000 year long glaciochemical series the greenland ice sheet project 2 glaciochemical series sodium potassium ammonium calcium magnesium sulfate nitrate and chloride provides a unique view of the chemistry of the atmosphere and the history of atmospheric circulation over both the high latitudes and mid low latitudes of the northern hemisphere interpretation of this record reveals a diverse array of environmental signatures that include the documentation of anthropogenically derived pollutants volcanic and biomass burning events storminess over marine surfaces continental aridity and biogenic source strength plus information related to the controls on both high and low frequency climate events of the last 110 000 years climate forcings investigated include changes in insolation of the order of the major orbital cycles that control the long term behavior of atmospheric circulation patterns through changes in ice volume sea level events such as the heinrich events massive discharges of icebergs first identified in the marine record that are found to operate on a 6100 year cycle due largely to the lagged response of ice sheets to changes in insolation and consequent glacier dynamics and rapid climate change events massive reorganizations of atmospheric circulation that are demonstrated to operate on 1450 year cycles changes in insolation and associated positive feedbacks related to ice sheets may assist in explaining favorable time periods and controls on the amplitude of massive rapid climate change events explanation for the exact timing and global synchroneity of these events is however more complicated preliminary evidence points to possible solar variability climate associations for these events and perhaps others that are embedded in our ice core derived atmospheric circulation records

glaciochemistry of polar ice cores a review human activities have already modified the chemical composition of the natural atmosphere even in very remote regions of the world the study of chemical parameters stored in solid precipitation and accumulated on polar ice sheets over the last several hundred thousand years provides a unique tool for obtaining information on the composition of the preindustrial atmosphere and its natural variability over the past this paper deals with the chemistry of polar ice focused on the soluble mineral na nh4 k ca mg h f cl no3 so4 and h2o2 and organic methanesulfonate ch3so3 formate hcoo acetate ch3coo and formaldehyde hcho species and their interpretation in terms of past atmospheric composition aerosols and water soluble gaseous species we discuss ice core dating the difficulties connected with trace measurements and the significance of the ionic composition of snow we examine temporal from the last decades back to the last climatic cycle and spatial including examples from coastal as well as central areas of greenland and antarctica variations in the ionic budget of the precipitation and evaluate ice core studies in terms of the chemical composition of our past atmosphere we review 1 how greenland and antarctic ice cores that span the last few centuries have provided information on the impact of human activities and 2 how the chemistry of deep ice cores provides information on various past natural phenomena such as climatic variations glacial interglacial changes el nino volcanic eruptions and large boreal forest fires

last interglacial climates the last interglacial commonly understood as an interval with climate as warm or warmer than today is represented by marine isotope stage mis 5e which is a proxy record of low global ice volume and high sea level it is arbitrarily dated to begin at approximately 130 000 yr b p and end at 116 000 yr b p with the onset of the early glacial unit mis 5d the age of the stage is determined by correlation to uranium thorium dates of raised coral reefs the most detailed proxy record of interglacial climate is found in the vostok ice core where the temperature reached current levels 132 000 yr ago and continued rising for another two millennia approximately 127 000 yr ago the eemian mixed forests were established in europe they developed through a characteristic succession of tree species probably surviving well into the early glacial stage in southern parts of europe after ca 115 000 yr ago open vegetation replaced forests in northwestern europe and the proportion of conifers increased significantly farther south air temperature at vostok dropped sharply pulses of cold water affected the northern north atlantic already in late mis 5e but the central north atlantic remained warm throughout most of mis 5d model results show that the sea surface in the eastern tropical pacific warmed when the ice grew and sea level dropped the essentially interglacial conditions in southwestern europe remained unaffected by ice buildup until late mis 5d when the forests disappeared abruptly and cold water invaded the central north atlantic ca 107 000 yr ago

paleoclimatic evidence for future ice sheet instability and rapid sea level rise sea level rise from melting of polar ice sheets is one of the largest potential threats of future climate change polar warming by the year 2100 may reach levels similar to those of 130 000 to 127 000 years ago that were associated with sea levels several meters above modern levels both the greenland ice sheet and portions of the antarctic ice sheet may be vulnerable the record of past ice sheet melting indicates that the rate of future melting and related sea level rise could be faster than widely thought

examining potential genetic links between jurassic porphyry cu au mo and epithermal au ag mineralization in the toodoggone district of north central british columbia canada the toodoggone district comprises upper triassic to lower jurassic hazelton group toodoggone formation volcanic and sedimentary rocks which unconformably overlie submarine island arc volcanic and sedimentary rocks of the lower permian asitka group and middle triassic takla group some of which are intruded by upper triassic to lower jurassic plutons and dikes of the black lake suite although plutonism occurred episodically from ca 218 to 191 ma the largest porphyry cu au mo systems formed from ca 202 to 197 ma with minor mineralization occurring from ca 197 to 194 ma porphyry style mineralization is hosted by small volume 468 c saline and deposited metals at deep crustal depths 2 km sulfur c o and pb isotope data confirm the involvement of a magmatic fluid but also suggest that the ore fluid interacted with asitka and takla group country rocks prior to metal deposition in contrast in the shasta lawyers and griz sickle low sulfidation epithermal systems there is no clear association with magmatic fluids instead their fluid inclusion data indicate the involvement of low temperature 175 to 335 c low salinity 1 to 11 equiv wt nacl fluids that deposited metals at shallow depths 850 m their isotope i e o h pb data suggest interaction between meteoric and or metamorphic ore fluids with basement country rocks

contemporaneous formation of adjacent porphyry and epithermal cu au deposits over 300 ka in northern luzon philippines there is commonly a close spatial relation between porphyry cu au and high sulfidation epithermal cu au deposits throughout the world although a genetic association has not been proven nowhere is this spatial association better seen than in northern luzon philippines where the lepanto epithermal cu au deposit overlies the far southeast fse porphyry cu au deposit both world class orebodies fresh rock and hydrothermal mineral separates yield k ar ages indicating that premineralization and postmineralization volcanism occurred at 2 2 1 8 ma and 1 2 0 9 ma respectively and that the hydrothermal system was active from 1 5 to 1 2 ma k ar ages of alunite from lepanto have the same range as those of hydrothermal biotite and illite from the fse deposit indicating that both epithermal and porphyry mineralization formed from an evolving magmatic hydrothermal system that was active for about 300 ka this temporal relation strengthens the argument for a genetic link between these two styles of ore deposit and has implications for exploration where one style of mineralization is found there is potential for the other nearby

substantial contribution to sea level rise during the last interglacial from the greenland ice sheet during the last interglacial period the eemian global sea level was at least three metres and probably more than five metres higher than at present1 2 complete melting of either the west antarctic ice sheet or the greenland ice sheet would today raise sea levels by 6 7 metres but the high sea levels during the last interglacial period have been proposed to result mainly from disintegration of the west antarctic ice sheet3 with model studies attributing only 1 2 m of sea level rise to meltwater from greenland4 5 this result was considered consistent with ice core evidence4 although earlier work had suggested a much reduced greenland ice sheet during the last interglacial period6 here we reconsider the eemian evolution of the greenland ice sheet by combining numerical modelling with insights obtained from recent central greenland ice core analyses our results suggest that the greenland ice sheet was considerably smaller and steeper during the eemian and plausibly contributed 4 5 5 m to the sea level highstand during that period we conclude that the high sea level during the last interglacial period most probably included a large contribution from greenland meltwater and therefore should not be interpreted as evidence for a significant reduction of the west antarctic ice sheet

orbital and millennial antarctic climate variability over the past 800 000 years a high resolution deuterium profile is now available along the entire european project for ice coring in antarctica dome c ice core extending this climate record back to marine isotope stage 20 2 800 000 years ago experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation we assessed the general correspondence between dansgaard oeschger events and their smoothed antarctic counterparts for this dome c record which reveals the presence of such features with similar amplitudes during previous glacial periods we suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records

bipolar changes in atmospheric circulation during the little ice age annually dated ice cores from siple dome west antarctica and central greenland indicate that meridional atmospheric circulation intensity increased in the polar south pacific and north atlantic at the beginning 1400 a d of the most recent holocene rapid climate change event the little ice age lia as deduced from chemical concentrations at these core sites the lia was characterized by substantial meridional circulation strength variability and this variability persists today despite strong evidence for an end to lia cooling thus increased late 20th century storm variability may be in part a result of the continuation of these climatic fluctuations

two mineralization events in the baiyinnuoer zn pb deposit in inner mongolia china evidence from field observations s pb isotopic compositions and u pb zircon ages abstract the xing mong orogenic belt xmob is located in the eastern part of the central asian orogenic belt caob and has experienced multiple tectonic events the baiyinnuoer pb zn deposit may be a rare case that documents two periods of mineralization in the tectonically complex xmob there are two types of pb zn mineralization in the deposit 1 skarn type ore hosted by the skarn in the contact zone between marble and granodiorite and within the marble and 2 vein type ore hosted by crystal tuff and feldspar porphyry this study revealed that the host rocks mineral assemblages mineralization occurrences s pb isotopes and ages between the two types of ore are notably different zircon u pb dating indicates that the granodiorite was emplaced in the early triassic 244 1 to 242 1 ma the crystal tuff was deposited in the early cretaceous 140 1 to 136 1 ma and the feldspar porphyry was intruded in the early cretaceous 138 2 to 136 2 ma the first skarn mineralization occurred at 240 ma and the second vein type pb zn mineralization took place between 136 and 129 ma thus the triassic orebodies were overprinted by early cretaceous mineralization the sphalerite and galena from the skarn mineralization have higher 34s values 4 7 to 0 3 than the sphalerite galena and aresenopyrite from the vein type mineralization 7 5 to 4 2 indicating different sulfur sources or ore forming processes for the two types of mineralization the pb isotopic compositions of the two types of ore are very similar suggesting similar lead sources geochemistry and nd pb hf isotopic systematics of the igneous rocks in the region show that the triassic granodiorite was generated from hybridization of mafic and felsic magmas due to strong crust mantle interaction under the collisional setting that resulted following the closure of the paleo asian ocean and the collision of north china and siberian cratons at the end of the permian while the cretaceous igneous rocks at baiyinnuoer originated from the partial melting of a juvenile lower crust with minor input from the crust caused by the underplating of mafic magma in an extensional setting

stratigraphy of the upper hazelton group and the jurassic evolution of the stikine terrane british columbia11ess contribution 20120051 the lower to middle jurassic hazelton group represents the final stage of magmatic arc activity in the intraoceanic stikine terrane which was followed by accretion within the cordilleran terrane c

southern ocean sea ice extent productivity and iron flux over the past eight glacial cycles sea ice and dust flux increased greatly in the southern ocean during the last glacial period palaeorecords provide contradictory evidence about marine productivity in this region but beyond one glacial cycle data were sparse here we present continuous chemical proxy data spanning the last eight glacial cycles 740 000 years from the dome c antarctic ice core these data constrain winter sea ice extent in the indian ocean southern ocean biogenic productivity and patagonian climatic conditions we found that maximum sea ice extent is closely tied to antarctic temperature on multi millennial timescales but less so on shorter timescales biological dimethylsulphide emissions south of the polar front seem to have changed little with climate suggesting that sulphur compounds were not active in climate regulation we observe large glacial interglacial contrasts in iron deposition which we infer reflects strongly changing patagonian conditions during glacial terminations changes in patagonia apparently preceded sea ice reduction indicating that multiple mechanisms may be responsible for different phases of co2 increase during glacial terminations we observe no changes in internal climatic feedbacks that could have caused the change in amplitude of antarctic temperature variations observed 440 000 years ago

geology fluid inclusion and h o s isotopes of the kuruer cu au deposit in western tianshan xinjiang china abstract western tianshan along the southwestern margin of the central asian orogenic belt is well endowed with epithermal and porphyry au deposits the kuruer cu au deposit recently discovered in the eastern part of western tianshan was considered as a high sulfidation epithermal deposit however our geological fluid inclusion and stable isotopic studies indicate that it actually formed in transition from high sulfidation to porphyry the host rocks include the dahalajunshan formation volcanic and volcano sedimentary rocks such as andesite rhyolite ignimbrite and tuff cu au mineralization mainly occurs as quartz dominated stockworks or disseminations with abundant pyrite and chalcopyrite and minor galena and sphalerite gold occurs as invisible phase in sulfides hydrothermal alteration includes a silicic core surrounded by phyllic alteration and peripheral propylitic alteration based on field observations paragenetic and crosscutting relationship the mineralization process can be roughly divided into three stages the early stage is characterized by the assemblage of quartz pyrite chalcopyrite while the middle stage contains quartz and chalcopyrite at absence of pyrite the late stage is characterized by calcite quartz chlorite chalcopyrite veins fluid inclusions at the early stage are mainly liquid rich aqueous and co2 rich inclusions and minor vapor rich aqueous and solid bearing inclusions their homogenization temperatures and salinities can be up to 420 c and 39 wt nacl eq respectively indicating that the initial ore forming fluids are high temperature high salinity h2o co2 nacl systems in the middle stage there are only liquid rich aqueous inclusions with homogenization temperatures and salinities of 130 190 c and 0 18 to 10 7 wt nacl eq respectively liquid rich aqueous inclusions in the late stage display much lower temperatures and salinities ranging from 110 to 130 c and 0 18 2 7 wt nacl eq respectively obtained dh2o and 18oh2o values of quartz from the middle stage are 98 to 107 and 2 1 to 0 74 respectively the 34s values of 9 chalcopyrite samples range from 10 2 to 2 4 with an average of 4 1 we conclude that the initial ore forming fluids are magmatic in origin and further cooled and diluted by mixing with meteoric water intensive fluid boiling and mixing facilitated hydrothermal alteration and mineralization

the taylor dome antarctic 18o record and globally synchronous changes in climate abstract the 18 o 16 o profile of a 554 m long ice core through taylor dome antarctica shows the climate variability of the last glacial interglacial cycle in detail and extends at least another full cycle taylor dome shares the main features of the vostok record including the early climatic optimum with later cool phase of the last interglacial period in antarctica taylor dome 18 o fluctuations are more abrupt and larger than those at vostok and byrd station although still less pronounced than those of the greenland gisp2 and grip records the influence of the atlantic thermohaline circulation on regional ocean heat transport explains the partly north atlantic character of this antarctic record under full glacial climate marine isotope stage 4 late stage 3 and stage 2 this marine influence diminished and taylor dome became more like vostok varying degrees of marine influence produce climate heterogeneity within antarctica which may account for conflicting evidence regarding the relative phasing of northern and southern hemisphere climate change

genesis of the changlingzi zn pb deposit in the southern great xing an range northeastern china constraints from fluid inclusions and h o s pb isotope systematics the changlingzi pb zn deposit is located in the southern great xing an range metallogenic belt of northeast china this deposit experienced two types of mineralization including skarn ore block i

homogeneous climate variability across east antarctica over the past three glacial cycles recent ice core studies have raised the disturbing possibility that glacial interglacial climate changes may be non uniform across antarctica1 2 these findings have been confined to records from the ross sea sector of the continent but significant deviations in other areas would call into question the widely assumed validity of the climate record obtained from vostok east antarctica on large spatial scales3 here we present an isotopic profile from a core drilled at dome fuji4 5 situated 1 500 km from vostok in a different sector of east antarctica the two records show remarkable similarities over the past three glacial cycles the extent of the dome fuji record in both large amplitude changes such as terminations interglacials and interstadials and more subtle glacial events even when the origin of precipitation is accounted for our results indicate that antarctic climate is essentially homogeneous at the scale of the east antarctic plateau possibly as a consequence of the symmetry of the plateau and the adjacent ocean

the last interglacial as represented in the glaciochemical record from mount moulton blue ice area west antarctica abstract understanding climate during the last interglacial is critical for understanding how modern climate change differs from purely naturally forced climate change here we present the first high resolution ice core record of the last interglacial and transition to the subsequent glacial period from antarctica and the first glaciochemical record for this period from west antarctica samples were collected from a horizontal ice trench in the mt moulton blue ice area bia in west antarctica and analyzed for their soluble major anions cl no 3 so 4 2 major and trace elements na mg ca sr cd cs ba la ce pr pb bi u as al s ti v cr mn fe co cu zn and water hydrogen isotopes d the last interglacial is characterized by warmer temperatures d weakened atmospheric circulation dust elements seasalts aerosols decreased sea ice extent na nssso 4 2 and decreased oceanic productivity nssso 4 2 a combined examination of mt moulton seasalts dust nssso 4 2 and d records indicates that the last interglacial was extremely stable compared to glacial age climate events and it ended through a long period of gradual cooling unlike that projected for future holocene climate

ore genesis and hydrothermal evolution of the baiyinnuo er zinc lead skarn deposit northeast china evidence from isotopes s pb and fluid inclusions the baiyinnuo er zinc lead deposit 32 74 mt at 5 44 zn 2 02 pb and 31 36 g t ag located in the south segment of the great xing an range is the largest zn pb deposit in northern china skarn and orebodies mainly occur between the different units of the huanggangliang formation or within the contact zone between the intrusions and permian marble several phases of igneous rocks exposed within the mining areas and among them the yanshanian plutonic rocks which intruded into limestone of the early permian huanggangliang formation are interpreted to be the source of ore since their pb isotope compositions 206pb 204pb 18 25 18 35 207pb 204pb 15 50 15 56 and 208pb 204pb 38 14 38 32 are highly consistent with the sulfides including sphalerite galena and chalcopyrite 206pb 204pb 18 23 18 37 207pb 204pb 15 47 15 62 and 208pb 204pb 37 93 38 44 sulfur isotope values of the sulfides give a narrow 34s interval of 6 1 to 4 6 mean 5 4 n 15 suggesting the ore forming fluid is of magmatic origin three main paragenetic stages of skarn formation and ore deposition have been recognized based on petrographic observation which are the preore stage garnet clinpyroxene wollastonite magnetite sulfides the synore stage sulfides epidote quartz calcite garnet and the postore stage calcite chlorite quartz fluorite several fluid evolution episodes can be inferred from microthermometric results at the baiyinnuo er zn pb deposit 1 immiscibility preore stage coexistence of halite bearing brine inclusions s1 type 44 wt nacl equiv and vapor rich fluid inclusions v type sharing the same homogenization temperatures 470 c confirms that fluid unmixing occurred under lithostatic pressures of 400 bars 1 5 km and the brine is considered to account for most prograde skarn minerals e g clinopyroxene 2 overpressure trapping preore stage brine inclusions homogenized by halite dissolution s2 type postdated the immiscible assemblages this type of inclusions is characterized by high but variable minimum trapping pressures 150 3 000 bars relative to s1 type inclusions and can be explained as a result of entrapment under overpressuring condition 3 boiling the presence of both vapor and liquid inclusions i e v and l type in the same assemblages within synore stage quartz calcite and sphalerite indicates the occurrence of fluid boiling 350 c at hydrostatic pressures of 150 bars and depth of 1 5 km which resulted in large scale mineralization in the baiyinnuo er zn pb deposit 4 mixing with external fluids fluid inclusions scattered within postore stage calcite or secondary trails in synore stage minerals show low homogenization temperatures 260 c and both decreasing for l type and increasing for cacl2 bearing inclusions i e lc type trends for salinities as homogenization temperatures decrease implying addition of both meteoric water low temperature low salinity and basinal brines low temperature ca rich respectively systematic fluid inclusion studies also indicate that the mineralization related fluid is of magmatic origin prograde minerals formed during the preore stage fluid immiscibility while sulfides deposition occurred during the synore stage fluid boiling mixing with external fluids began as the hydrothermal system cooled to 300 c when the main metal precipitation process had ended

the source and evolution of ore fluids in the heiniuwa gold deposit baoshan block sanjiang region constraints from sulfide trace element fluid inclusion and stable isotope studies abstract the heiniuwa gold deposit is located in the northwestern segment of the longyang au fe pb zn polymetallic ore cluster in the northern baoshan block sanjiang region sw china this ore cluster is characterized by skarn fe pb zn mineralization 120 ma in the central part and au mineralization in the distal part the genesis of the heiniuwa deposit and its relationship with the skarn deposits remain unclear all orebodies in heiniuwa are hosted in the upper cambrian calcareous slate and siltstone of the hetaoping formation and are controlled by the ns striking faults three main paragenetic stages of mineralization have been recognized based on petrographic observation including from early to late a pyrite arsenopyrite quartz stage stage i a pyrite pyrrhotite sphalerite galena chalcopyrite quartz calcite stage stage ii and a quartz calcite chlorite stage stage iii three types of fluid inclusions were identified in the quartz and calcite from the stage i to iii in heiniuwa including liquid rich l type vapor rich v type and solid bearing s type inclusions the s type inclusions only occur in stage i quartz the fluid inclusions from stage i homogenized at 185 326 c concentrating at 220 250 c with eutectic temperatures of 48 5 c to 36 7 c final ice melting temperatures of 11 34 c to 0 8 c and salinities ranging from 1 4 to 17 2 wt nacl equiv the inclusions from stage ii homogenized at 155 281 c concentrating at 190 230 c with eutectic temperatures of 51 6 c to 37 5 c final ice melting temperatures of 10 6 c to 0 5 c and corresponding salinities ranging from 0 9 to 14 6 wt nacl equiv the inclusions from stage iii homogenized at 116 202 c concentrating at 150 170 c with eutectic temperature of 45 5 c to 37 5 c final ice melting temperatures of 4 3 c to 0 6 c and salinities ranging from 1 3 to 7 2 wt nacl equiv the microthermometry reveals that the ore forming fluid of heiniuwa gold deposit is a typical h 2 o nacl cacl 2 fluid system the carbon and oxygen isotopes of calcite show that 13 c pdb and 18 o smow values respectively range from 13 4 to 6 8 and 9 1 to 9 6 in stage ii and from 8 1 to 1 5 and 6 4 to 8 2 in stage iii the bulk marble and calcareous slate samples have 13 c pdb and 18 o smow values from 3 0 to 0 7 and 7 8 to 11 9 respectively this suggests that the carbon in the ore forming fluid was probably from a magmatic source the 18 o fluid values of ore forming fluid vary from 1 6 to 2 5 in stage i from 6 2 to 0 6 in stage ii and from 10 8 to 2 5 in stage iii this indicates that the fluid in stage i is dominantly magmatic whereas the fluid in stage iii is close to meteoric water the decrease of na ca ratios of ore forming fluid from stage i to stage iii suggests that the interaction with carbonate wallrock is significant during fluid evolution the sulfide 34 s values range from 5 7 to 4 6 mean 0 3 n 19 agreeing with the explanation based on c o isotopes and fluid inclusions that the ore forming fluids are mainly magmatic in origin in addition la icp ms analysis of sulfides also supports this opinion the stage i pyrite has cu ni ratios greater than 1 and a high concentration of gold in contrast the stage ii pyrrhotite samples display a very low concentration of gold this suggests that gold mineralization mainly occurred in stage i the mixing between magmatic hydrothermal fluid and meteoric water is considered to be a key factor controlling the gold deposition

a 200 year sub annual record of sulfate in west antarctica from 16 ice cores sixteen high resolution ice core records from west antarctica and south pole are used to examine the spatial and temporal distribution of sulfate for the last 200 years the preservation of seasonal layers throughout the length of each record results in a dating accuracy of better than 1 year based on known global scale volcanic events a dual transport source for west antarctic sea salt ss so4 2 and excess xs so4 2 is observed lower tropospheric for areas below 1000 m elevation and mid upper tropospheric stratospheric for areas located above 1000 m our xsso4 2 records with volcanic peaks removed do not display any evidence of an anthropogenic impact on west antarctic so4 2 concentrations but do reveal that a major climate transition takes place over west antarctica at 1940 global scale volcanic eruptions appear as significant peaks in the robust spline residual xsso 4 2 records from sites located above 1000 m elevation but do not appear in the residual records from sites located below 1000 m

temporal variations and sources of elements in the south pole atmosphere 1 nonenriched and moderately enriched elements high volume particle samples were collected from 1979 to 1983 from the south pole atmosphere and analyzed by nuclear methods the new results are combined with similar studies at the south pole there is no trend of concentrations during 12 years of sampling but concentrations of elements fluctuate through seasonal cycles concentrations of elements associated with crustal dust and sea salt showed opposite seasonal variations concentrations of most crustal elements are low during winters but double during summers concentration of marine elements are low in the summers and high in winters enrichment factors of some crustal elements such as ba la ce yb and hf are higher in the winter than summer indicating the presence of a second crustal component with a different chemical composition in the south pole atmosphere a similar difference in the crustal enrichment factor of co is due to the influence of volcanic or anthropogenic sources sulfate seasalt meteoritic particles volatiles and two different types of crustal particles are found to be components of the south polar aerosols the relative contribution of each component to total aerosol mass is as follows crustal 4 0 in summer 2 5 in winter marine elements 16 6 in summer 78 6 in winter sulfate 77 5 in summer 18 0 in winter meteoritic particles 0 1 in summer 0 1 in winter volatiles 0 9 in summer 0 5 in winter crustal component ii 0 8 in summer 0 7 in winter

duration and structure of the past four interglaciations reanalysis and additional dating of the devils hole 18o paleotemperature record confirm that the last interglaciation in the great basin the continental analog of marine isotopic substage 5e lasted 22 000 yr consistent with the vostok paleotemperature record which suggests a duration of 19 000 yr for this event in antarctica the three preceding interglaciations in the devils hole record analogs of marine isotopic substages 7e 9c and 11c range from 20 000 to 26 000 yr in duration a 20 000 yr duration for the last interglaciation is consistent with tims uranium series dated sea level high stands thus the widely held view that interglaciations were of 11 000 to 13 000 yr duration and constituted only about 10 of mid to late pleistocene climatic cycles needs reexamination the warmest portion of each interglaciation in the devils hole time series is marked by a 18o plateau signifying apparent climatic stability for periods of 10 000 to 15 000 yr duration

hydrothermal evolution and ore genesis of the beiya giant au polymetallic deposit western yunnan china evidence from fluid inclusions and h o s pb isotopes abstract the beiya porphyry skarn gold polymetallic deposit is one of the largest gold deposits in china and also contains significant amounts of silver and base metals the estimated reserve at the end of 2015 was 130 million metric tonnes mt of ores grading 2 42 g t au 0 48 wt cu 25 5 wt fe 38 85 g t ag 1 24 wt pb and 0 53 wt zn the deposit is located in the jinshajiang ailaoshan porphyry skarn cu mo au metallogenic belt in western yunnan province southwest china skarn alteration and mineralization are spatially and temporally associated with eocene monzogranite porphyries which were emplaced into triassic carbonates field evidence and petrographic observations indicate there are four stages of hydrothermal activity i e prograde stage i iron oxide stage ii sulfide stage iii and carbonate stage stage iv stage i is characterized by the formation of garnet and pyroxene by high temperature 398 560 c hypersaline 48 81 67 24 wt nacl equiv hydrothermal fluids with h o isotopic compositions that are similar to typical magmatic fluids these fluids were most likely generated by the separation of brine from a silicate melt in stage ii garnet and pyroxene was replaced by epidote amphibole chlorite quartz and magnetite associated hydrothermal fluids are preserved in coexisting l type and v type fluid inclusions and are characterized by anomalously low d values approximately 80 and lower 18 o than stage i fluids the decrease in ore fluid 18 o h2o values with time coincided with marked decreases in fluid salinity and temperature based on the fluid inclusion and stable isotopic data we suggest that the ore fluid evolved by boiling of the magmatic brine stage iii is characterized by the development of pyrite chalcopyrite galena and sphalerite fluids inclusions associated with stage iii display and continuous range of salinities with the majority being low salinity inclusions 1 28 3 54 wt nacl equiv these fluids yield lower 18 o h2o values 0 85 to 5 52 and moderate d values 78 6 to 88 6 altogether these data indicate that stage iii fluids originated from the mixing of residual stage ii fluids with meteoric water the sulfur isotope 34 s values of stage iii sulfides cover a narrow range of 4 2 to 1 2 mean 1 1 and boiling also occurred at low temperatures 165 347 c during stage iii in stage iv only l type fluid inclusions are present which yielded the lowest homogenization temperatures 157 272 c and the lowest salinities 1 06 12 20 wt nacl equiv the h o isotope data indicate that the ore forming fluids were dominated by magmatic water in stage i and stage ii and that the magmatic water gradually mixed with circulating meteoric water during stage iii and stage iv this conclusion is further supported by the isotopic composition of lead of the ores which is similar to that of the monzogranite porphyries but differs significantly from permian basalts and triassic wall rocks

geochronological and geochemical constraints on the genesis of the huanren skarn cu zn deposit northeast china abstract the huanren skarn cu zn deposit is located in southeastern liaoning on the eastern edge of the north china craton ncc in this paper we present a study on the geochronologic geochemical and sr nd hf and s isotopic data for the magmatic rocks and sulfide minerals exposed in the deposit laser ablation inductively coupled plasma mass spectrometry la icp ms dating of zircon grains from two mining pits in the monzodiorite yields ages of 128 2 1 1 ma and 128 6 1 5 ma these results indicate that the magmatism in the huanren cu zn deposit might have occurred in the early cretaceous geochemically the huanren monzodiorite belongs to the high k calc alkaline and shoshonitic series is enriched in rb ba and k and is depleted in nb ta and ti the rocks also have relatively high 87sr 86sr i 0 7091 0 7099 and low end t 13 2 to 10 3 and ehf t values 14 3 to 7 8 the sr nd hf isotopic data for the monzodiorite indicate that the magma may be derived from mixed sources of the crust and mantle the 34s values of chalcopyrite galena and pyrite range from 4 4 to 5 8 with an average of 5 1 indicating that the sulfur in the deposit was mainly derived from a magmatic source the huanren cu zn deposit resulted from the magmatism and mineralization induced by the rollback of the paleo pacific plate

physico chemical controls on ore deposition in the arapucandere pb zn cu precious metal deposit biga peninsula nw turkey abstract arapucandere is one of a number of similar cu zn pb au ag epithermal deposits in the biga peninsula which are mineralogically and tectonically similar fluid inclusions have very low salinities between 1 7 and 0 wt nacl and a wide range of temperatures from 360 to 160 c there was extensive boiling and flashing of the hydrothermal fluids which initiated mineral deposition the range of temperatures is consistent with emplacement of the veins at 700 m depth with the pressure decreasing from near lithostatic to near hydrostatic and a decrease in temperature to 250 c due to adiabatic expansion of the fluids there is evidence of a limited amount of boiling but the temperature and pressure decrease was close to the liquid vapour curve flashing of the fluids was caused by sudden drops to sub hydrostatic pressures and even lower temperatures mineralization was caused by these pressure related temperature decreases as there is no evidence of cooling and dilution of the ore fluids 34 s values of sulphides indicate a magmatic source but the more negative than usual values also suggest boiling affected isotopes d and 18 o of the fluids indicate a mixing between meteoric waters and magmatic fluids with the large range of d due to boiling la icp ms analyses of fluid inclusions reveal high cu zn pb concentrations in the fluids despite their low salinity transported as chloride complexes exceptional pressure and temperature decrease causing the fluids to flash was likely to have been in response to earthquakes

northern hemisphere forcing of climatic cycles in antarctica over the past 360 000 years the milankovitch theory of climate change proposes that glacial interglacial cycles are driven by changes in summer insolation at high northern latitudes the timing of climate change in the southern hemisphere at glacial interglacial transitions which are known as terminations relative to variations in summer insolation in the northern hemisphere is an important test of this hypothesis so far it has only been possible to apply this test to the most recent termination because the dating uncertainty associated with older terminations is too large to allow phase relationships to be determined here we present a new chronology of antarctic climate change over the past 360 000 years that is based on the ratio of oxygen to nitrogen molecules in air trapped in the dome fuji and vostok ice cores this ratio is a proxy for local summer insolation5 and thus allows the chronology to be constructed by orbital tuning without the need to assume a lag between a climate record and an orbital parameter the accuracy of the chronology allows us to examine the phase relationships between climate records from the ice cores and changes in insolation our results indicate that orbital scale antarctic climate change lags northern hemisphere insolation by a few millennia and that the increases in antarctic temperature and atmospheric carbon dioxide concentration during the last four terminations occurred within the rising phase of northern hemisphere summer insolation these results support the milankovitch theory that northern hemisphere summer insolation triggered the last four deglaciations

the red chris porphyry copper gold deposit northern british columbia canada igneous phases alteration and controls of mineralization red chris is a late triassic porphyry cu au mo deposit in the stikinia island arc terrane in northern b c late triassic sedimentary and volcanic rocks of the stuhini group host a series of late triassic to early jurassic 204 198 ma diorite to quartz monzonite stocks and dikes the red chris deposit is hosted in the 204 ma red stock the largest 6 5 1 5 km and most altered intrusion in the area volcanic rocks approximately time equivalent with the stock are exposed 2 km to the southwest and west postmineral early and middle jurassic sedimentary rocks unconformably overlie the stuhini group and red stock to the south and southeast the composite red stock consists of multiple phases of crowded porphyries 30 65 plagioclase hornblende biotite phenocrysts including abundant premineral p1 leucodiorite multiple subphases of synmineral p2 quartz monzonite porphyries and volumetrically minor late mineral monzonite p3 and monzodiorite p4 porphyries the stock evolved from subalkaline to silica saturated alkalic composition with the mineral related p2 porphyries being high k calcalkalic and high sr y common septa of stuhini biotitic hornfels are entrapped within the stock minor postmineral weakly altered mafic dikes cut the stock the zone of 0 25 cu equiv cu au is 2 km long wsw ene and up to 650 m wide early a type quartz veins with disseminated bornite accompanied biotitic and k feldspar magnetite alteration which was coeval with p2 porphyries higher cu and au grades correlate in a general way with zones of more abundant a veins chlorite carbonate epidote actinolite replaced hornblende peripheral to biotitic alteration and chlorite overprinted much of the secondary biotite late alteration affected all porphyry phases and is subdivided into earlier sericite clay pyrite and later low sulfide carbonate clay hematite late sericite clay pyrite alteration sulfidized much of the primary bornite to chalcopyrite with or without pyrite and carbonate clay hematite alteration converted most magnetite to hematite highest cu au grades 2 cu equiv occur in and around the early and intermediate stage p2 porphyries zoning of cu au au cu ratios sulfides and quartz veins is centered and mostly symmetrical around a core of high grade cu au within and surrounding apices of p2 porphyry contact relationships confirm the close association of p2 porphyry phases with cu au zones of 50 ppm mo surround the highest grade cu au zone at depth west northwest and east northeast strike slip to oblique slip faults offset sulfide cu au and mo patterns several lines of evidence indicate 15 to 20 of southward tilt since the system formed due to glaciation oxidation is very thin and supergene enrichment negligible red chris was previously considered by most workers as an alkalic or hybrid alkalic deposit new chemical data on synmineral porphyry phases instead suggest high k calc alkalic composition similar to the monzonitic cu mo au class of porphyry deposits which includes bingham and bajo de la alumbrera red chris is also classified as an a vein type deposit due to strong control of higher grade cu au by a vein stockworks with abundant disseminated cu sulfides

complexity of holocene climate as reconstructed from a greenland ice core glaciochemical time series developed from summit greenland indicate that the chemical composition of the atmosphere was dynamic during the holocene epoch concentrations of sea salt and terrestrial dusts increased in summit snow during the periods 0 to 600 2400 to 3100 5000 to 6100 7800 to 8800 and more than 11 300 years ago the most recent increase and also the most abrupt coincides with the little ice age these changes imply that either the north polar vortex expanded or the meridional air flow intensified during these periods and that temperatures in the mid to high northern latitudes were potentially the coldest since the younger dryas event

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

geological and isotopic evidence for magmatic hydrothermal origin of the ag pb zn deposits in the lengshuikeng district east central china the lengshuikeng ore district in east central china has an ore reserve of 43 mt with an average grade of 204 53 g t ag and 4 63 pb zn based on contrasting geological characteristics the mineralization in the lengshuikeng ore district can be divided into porphyry hosted and stratabound types the porphyry hosted mineralization is distributed in and around the lengshuikeng granite porphyry and shows a distinct alteration zoning including minor chloritization and sericitization in the proximal zone sericitization silicification and carbonatization in the peripheral zone and sericitization and carbonatization in the distal zone the stratabound mineralization occurs in volcano sedimentary rocks at 100 400 m depth without obvious zoning of alterations and ore minerals porphyry hosted and stratabound mineralization are both characterized by early stage pyrite chalcopyrite sphalerite middle stage acanthite native silver galena sphalerite and late stage pyrite quartz calcite the 34s values of pyrite sphalerite and galena in the ores range from 3 8 to 6 9 with an average of 2 0 the c o isotope values of siderite calcite and dolomite range from 7 2 to 1 5 with an average of 4 4 v pdb and from 10 9 to 19 5 with an average of 14 8 v smow respectively hydrogen oxygen and carbon isotopes indicate that the hydrothermal fluids were derived mainly from meteoric water with addition of minor amounts of magmatic water geochronology employing la icp ms analyses of zircons from a quartz syenite porphyry yielded a weighted mean 206pb 238u age of 136 3 0 8 ma considered as the emplacement age of the porphyry rb sr dating of sphalerite from the main ore stage yielded an age of 126 9 7 1 ma marking the time of mineralization the lengshuikeng mineralization classifies as an epithermal ag pb zn deposit

porphyry deposits of the northwestern cordillera of north america edited by t g schroeter special volume 46 canadian institute of mining metallurgy and petroleum montreal 1995 888 pp canadian 95 plus 15 handling isbn 0 919086 56 x

jurassic epithermal deposits in the toodoggone river area northern british columbia examples of well preserved volcanic hosted precious metal mineralization epithermal gold silver deposits in the toodoggone river area are hosted by early jurassic high k trachyandesite and trachydacite volcanic rocks that erupted during two major cycles spanning roughly 7 m y volcanism and related plutonic activity is intimately associated with the structural development of an elongate volcano tectonic depression in which extensional fracture zones confine the epithermal deposits younger sedimentary rocks overlay and protected the deposits from erosion gold and silver in the toodoggone district occur most commonly in quartz veins associated with adularia sericite and calcite locally gold barite veins cut volcanic rocks that are pervasively replaced by varying proportions of fine grained silica dickite and natroalunite fluid inclusions in quartz from most precious metal vein deposits are typical of epithermal environments they contain low temperature dilute hydrothermal fluids of predominantly meteoric origin t h 300 degrees c and 30 equiv wt nacl light stable isotope analyses show marked 18 o enrichment in the volcanic rocks hydrothermally altered host rocks and mineralized vein quartz with adularia or sericite of about 8 per mil the isotopic composition of the hydrothermal fluid is calculated to be about delta 18 o 0 per mil these hydrothermal fluids are isotopically evolved mixtures derived from meteoric and magmatic waters with possible metamorphic input whole rock analyses of mainly fine grained quartz dickite mineral mixtures document the largest 18 o shifts with values up to 15 7 per mil this is interpreted to be due to lower temperatures and or the presence of significant quantities of magmatic fluids in these altered zones k ar age determinations on alunite from several zones of intensely acid leached rocks suggest that an early mineralizing episode apparently occurred around 190 ma or earlier during a depositional hiatus between the two major volcanic cycles this coincides with the uplift and cooling of several plutons k ar dates on adularia and sericite from precious metal bearing quartz veins some of which are from volcanic rocks of the upper cycle suggest that there was also a younger mineralizing event recent argon step heating dates indicate that the major gold silver deposits with adularia sericite range from 189 7 or 2 6 to 186 7 or 1 7 ma clark and williams jones 1991 this closely follows the latest stages of toodoggone volcanism and fault block subsidence a depth zoning model for mineralization illustrates the two types of epithermal regimes adularia sericite and acid sulfate gold barite in the extensive advanced argillic and argillicly altered zones at the al deposit represent high level near surface acid sulfate alteration formed on the flanks of a stratovolcano the advanced argillic altered zone at silver pond next to the major lawyers adularia sericite deposit represents a downfaulted acid sulfate outflow i e the upper portion of the lawyers hydrothermal system the lawyers deposit and most of the other occurrences are adularia sericite type deposits formed at slight depth these deposits occur in grabens or half grabens in an extensional fault regime that created the central toodoggone depression nested within the broader volcanic belt

can deep seated gravitational slope deformations be activated by regional tectonic strain first insights from displacement measurements in caves from the eastern alps abstract tectonic elastic strain and ground deformations are documented as the most remarkable environmental phenomena occurring prior to local earthquakes in tectonically active areas the question arises if such strain would be able to trigger mass movements we discuss a directly observed fault slip and a subsequent minor activation of a deep seated gravitational slope deformation prior to the m 3 bad fischau earthquake between end of november and early december 2013 in ne austria the data originate from two faults in the emmerberg and eisenstein caves in the transition zone between the eastern alps and the vienna basin monitored in the framework of the fwf speleotect project the fault slips have been observed at the micrometer level by means of an opto mechanical 3d crack gauge tm 71 the discussed event started with the fault activation in the emmerberg cave on 25 november 2013 recorded by measurements of about 2 m shortening and 1 m sinistral parallel slip which was fully in agreement with the macroscopically documented past fault kinematics one day later the mass micro movement activated on the opposite side of the mountain ridge in the eisenstein cave and it continued on three consecutive days further the fault in the emmerberg cave experienced also a subsequent gravitational relaxation on 2 3 december 2013 when the joint opened and the southern block subsided towards the valley while the original sinistral displacement remained irreversible the process was followed by the m 3 earthquake in bad fischau on 11 december 2013 our data suggest that tectonic strain could play a higher role on the activation of slow mass movements in the area than expected although we cannot fully exclude the co activation of the mass movement in the eisenstein cave by water saturation the presented data bring new insight into recent geodynamics of the eastern alps and the vienna basin for better interpretations and conclusions however we need a much longer period of observations

ore genesis and hydrothermal evolution of the huanggang skarn iron tin polymetallic deposit southern great xing an range evidence from fluid inclusions and isotope analyses abstract the southern great xing an range is one of the most important metallogenic belts in northern china and contains numerous pb zn ag cu sn fe mo deposits the huanggang iron tin polymetallic skarn deposit is located in the sn polymetallic metallogenic sub belt skarns and iron orebodies occur as lenses along the contact between granite plutons and the lower permian huanggangliang formation marble or dashizhai formation andesite field evidence and petrographic observations indicate that the three stages of hydrothermal activity i e skarn oxide and sulfide stages all contributed to the formation of the huanggang deposit the skarn stage is characterized by the formation of garnet and pyroxene and high temperature hypersaline hydrothermal fluids with isotopic compositions that are similar to those of typical magmatic fluids these fluids most likely were generated by the separation of brine from a silicate melt instead of being a product of aqueous fluid immiscibility the iron oxide stage coincides with the replacement of garnet and pyroxene by amphibole chlorite quartz and magnetite the hydrothermal fluids of this stage are represented by l type fluid inclusions that coexist with v type inclusions with anomalously low d values approximately 100 to 116 the decrease in ore fluid 18oh2o values with time coincides with marked decreases in the fluid salinity and temperature based on the fluid inclusion and stable isotopic data the ore fluid evolved by boiling of the magmatic brine the sulfide stage is characterized by the development of sphalerite chalcopyrite fluorite and calcite veins and these veins cut across the skarns and orebodies the fluids during this stage are represented by inclusions with a variable but continuous sequence of salinities mainly low salinity inclusions these fluids yield the lowest 18oh2o values and moderate d values 1 6 to 2 8 and 101 to 104 respectively the data indicate that the sulfide stage fluids originated from the mixing of residual oxide stage fluids with various amounts of meteoric water boiling occurred during this stage at low temperatures the sulfur isotope 34s values of the sulfides are in a narrow range of 6 70 to 4 50 mean 1 01 and the oxygen isotope 18o values of the magnetite are in a narrow range of 0 1 to 3 4 both of these sets of values suggest that the ore forming fluid is of magmatic origin the lead isotope compositions of the ore 206pb 204pb 18 252 18 345 207pb 204pb 15 511 15 607 and 208pb 204pb 38 071 38 388 are consistent with those of k feldspar granites 206pb 204pb 18 183 18 495 207pb 204pb 15 448 15 602 208pb 204pb 37 877 38 325 but significantly differ from those of permian marble 206pb 204pb 18 367 18 449 207pb 204pb 15 676 15 695 208pb 204pb 38 469 38 465 which also suggests that the ore forming fluid is of magmatic origin

soluble and insoluble lithium dust in the epica domec ice core implications for changes of the east antarctic dust provenance during the recent glacial interglacial transition continental dust impurities in antarctic ice provide information on climate changes in the dust source areas and on past atmospheric circulation we investigated records of dust species from the last 45 ka in the east antarctic epica domec edc ice core with special emphasis on the lithium li content of dust we obtained two complementary li records using a new ion chromatography ic technique in line with inductively coupled plasma sector field mass spectroscopy icp sfms concentrations of soluble li li were obtained using ic while total concentrations of li lit were obtained using icp sfms providing an ideal opportunity to investigate the soluble and insoluble chemistry of li in east antarctic dust over the last glacial interglacial transition the records show that changes in the solubility of li are associated with climatic changes for the late glacial period and the antarctic cold reversal acr a large fraction up to 75 of the lit content is present as insoluble minerals whereas for the holocene period it seems that li is present mainly as soluble salts li we compared the concentrations of li with the concentrations of ca2 and the mass and size characteristics of the dust which were obtained using coulter counting cc furthermore we compared the concentrations of lit with the concentrations of bat our analysis suggests that the changes in solubility of li along the edc ice core are related to changes in compositions of the dust minerals during the late glacial period changes in the dust composition is characteristic of variations in the strength of the atmospheric circulation while changes over the last glacial interglacial transition are indicative of a change in the major dust source areas the dust characteristics for the glacial and the holocene periods indicate two different dust types the glacial dust type partly disappeared after the acr while the holocene dust type appeared significantly after around 16 ka bp and became dominant after the acr the relative increase in the holocene dust type at the glacial interglacial transition could be due to changed conditions in the potential source area or to changed patterns of atmospheric circulation resulting in enhanced transport from a source area that was different from the glacial source areas

a 150 000 year climatic record from antarctic ice during much of the quaternary the earth s climate has undergone drastic changes most notably successive glacial and interglacial episodes the past 150 kyr includes such a climatic cycle the last interglacial the last glacial and the present holocene interglacial a new climatic time series for this period has been obtained using 18 o data from an antarctic ice core

a 200 year sulfate record from 16 antarctic ice cores and associations with southern ocean sea ice extent chemistry data from 16 50 115m deep sub annually dated ice cores are used to investigate spatial and temporal concentration variability of sea salt ss so4 2 and excess xs so4 2 over west antarctica and the south pole for the last 200 years low elevation ice core sites in western west antarctica contain higher concentrations of so4 2 as a result of cyclogenesis over the ross ice shelf and proximity to the ross sea polynya linear correlation analysis of 15 west antarctic ice core so4 2 time series demonstrates that at several sites concentrations of ssso4 2 are higher when sea ice extent sie is greater and the inverse for xsso4 concentrations of xsso4 2 from the south pole site east antarctica are associated with sie from the weddell region and west antarctic xsso4 2 concentrations are associated with sie from the bellingshausen amundsen ross region the only notable rise of the last 200 years in xsso4 around 1940 is not related to sie fluctuations and is most likely a result of increased xsso4 2 production in the mid low latitudes and or an increase in transport efficiency from the mid low latitudes to central west antarctica these high resolution records show that the source types and source areas of ssso4 2 and xsso4 2 delivered to eastern and western west antarctica and the south pole differ from site to site but can best be resolved using records from spatial ice core arrays such as the international trans antarctic scientific expedition itase

glacial interglacial variations in central east antarctic ice accumulation rates past rates of ice accumulation in central east antarctica are defined poorly for the last glacial period ice cores from which current estimates are based are limited in number there is one deep ice core at vostok station one at dome f and two others currently being extracted at dome c and dronning maud land and are restricted spatially they are one dimensional here spatial variations in ice accumulation rates during the last glacial are calculated from isochronous internal ice sheet layering measured by airborne ice penetrating radar data the layers are used to identify the stratigraphy around five east antarctic ice domes isochrons are dated by linking them to the vostok ice core and in one case the epica dome c ice core this chronostratigraphy allows the depth age function to be identified across the ice sheet a simple ice flow model using the depth age measurements as input is then used to determine the spatial and temporal variation in east antarctic ice accumulation over the last glacial cycle the lowest rates of ice accumulation were predicted in the full glacial period to the south of dome a and ridge b there are two possible explanations for this 1 the ice divide topographies may have caused a precipitation shadow in the ice age 2 with the expansion of the ross ice shelf the area to the south of dome a and ridge b would be at the very centre of the ice sheet and hence at a maximum distance from the ocean moisture source r 2002 elsevier science ltd all rights reserved

sea level pressure variability in the amundsen sea region inferred from a west antarctic glaciochemical record using european center for medium range weather forecasts ecmwf numerical operational analyses sea ice extent records and station pressure data we investigate the influence of sea level pressure variability in the amundsen sea region on a west antarctic siple dome glaciochemical record empirical orthogonal function analysis of the high resolution siple dome multivariate ice core chemical time series record sdeof1 documents lower tropospheric transport of sea salt aerosols to the site during 1985 1994 the sdeof1 record of high low aerosol transport corresponds to anomalously low high sea level pressure slp in the amundsen sea region spatial correlation patterns between ecmwf monthly slp fields and the annual sdeof1 record suggest that a majority of sea salt aerosol is transported to siple dome during spring september october and november analysis of zonal and meridional wind fields supports the slp sdeof1 correlation and suggests the sdeof1 record is sensitive to changes in regional circulation strength no relationship is found between sea ice extent and the sdeof1 record for the period 1973 1994 to investigate the sdeof1 record prior to ecmwf coverage a spring transpolar index stpi is created using normalized slp records from the new zealand and south america antarctic peninsula sectors and is significantly correlated at least 95 c l with the sdeof1 record on an annual r 5 0 32 p 0 001 and interannual 3 years r 5 0 51 p 0 001 basis dominant periodicities 3 3 and 7 1 years in the annual sdeof1 record 1890 1994 a d suggest that a portion of the recorded interannual variability may be related tropical extratropical enso teleconnections changes in the periodic structure of the full 850 1994 a d siple dome record suggests a shift in slp forcing during the little ice age 1400 1900 a d interval

trace elements in vostok antarctic ice during the last four climatic cycles li v cr mn co as rb sr ba bi and u were determined by inductively coupled plasma sector field mass spectrometry icp sfms in various sections of the 3623 m vostok deep antarctic ice core dated from 4600 to 410 000 years bp which corresponds to the last four climatic cycles back to isotopic stage 11 3 concentrations of all elements were found to be highly variable with low values during interglacial periods and warm interstadials and much higher values during the coldest periods of the last four ice ages crustal enrichment factors suggest various sources for the different elements rock and soil dust is the dominant source of v mn rb ba and u whatever the period and of li cr co sr and as during cold periods sea salt aerosol together with aeolian dust also contributes significantly to sr whereas volcanic emissions could provide a significant input for as and bi especially during warm periods