study of particles in the ascending gas of ruptures caused by the 2008 wenchuan earthquake abstract ascending gas is a global phenomenon it can move upwards along faults or fissures from the interior of the earth to the surface of the earth seismically active regions near continental plate boundaries are active regions of ascending gas based on the results of previous research abnormal concentrations of so 2 co 2 rn he h 2 o 2 ar n 2 and ch 4 in ascending gas may be applied to earthquake prediction in our study particles carried by ascending gas in ruptures caused by the wenchuan earthquake have been discovered using a transmission electron microscope it can be seen that there are far more particles in the ascending gas of ruptures caused by the 2008 earthquake than there are in the ascending gas of the non seismic fengguanshan fault or the ascending gas of the soil in wufeng town of jintang county or yuhe village of pengshan county which represent background areas the abnormal characteristics of the particles carried by the ascending gas of ruptures also include cu hg and os enriched particles the typical elemental associations are fe mn ni cr and pb cr sio 2 particles contain abnormally high contents of impure elements in the form of particles that have been encapsulated by sio 2 this is the first study to report the presence of particles carried by ascending gas in earthquake ruptures this study represents a new method of earthquake prediction these particles can provide us with abundant and direct information about earthquake activity which can be applied to earthquake prediction characteristics of the particles in the ascending gas combined with the concentrations of hg so 2 co 2 rn he h 2 o 2 ar n 2 and ch 4 can be used to develop a more efficient method of earthquake prediction

magmatism geological setting alteration and metallogenic potential of donghua area dehua county fujian province southeast china insights from porphyry zircon u pb and pyrite rb sr geochronology geochemistry and remote sensing abstract located in the southern section of the wuyi mountain metallogenic belt the dehua youxi yongtai dyy ore district is one of the potential areas of gold deposits in the fujian province southeast china gold mineralization is widely distributed in this district including qiucun shuangqishan ancun and dongyang gold deposits however the dyy ore district is still at a low degree of exploration and research this paper focuses on the donghua area in the northwest of the dyy ore district as its typical and integrated volcano magma mechanism revealed in this study combined approaches including zircon shrimp u pb geochronology rb sr isochron dating and mineral chemistry of pyrite and hyperspectral remote sensing are employed aiming to identify the magmatism alteration geological setting and metallogenic potential of the donghua area the zircon shrimp u pb ages of the granite porphyritic dykes in donghua are 154 6 1 1 ma and 153 2 1 2 ma respectively indicating that the dykes were formed in the late jurassic the rb sr geochronological age of hydrothermal epithermal pyrite in donghua is 153 7 2 4 ma which is almost coeval with that of the granite porphyritic dykes within error and consistent with the regional volcanic magmatic activity and the metallogenic age of the regional metallogenic event the granitic dykes in donghua exhibit the characteristics of both a type and i type granitoids thus indicating the presence of transitional geochemical characteristics as a result of the subduction of the pacific plate towards the eurasia the ca 154 153 ma magmatic event in the donghua area occurred at the beginning of large scale delamination of the continental crust the zoning distribution of the mineral alteration of chlorite dickite kaolinite and gypsum the interpretation of volcanic activity from the annular structure of hyperspectral remote sensing and the inferred deep seated intrusion emplacing from northwest to southeast are in agreement thus displaying the volcano magma alteration mechanism developed in the donghua area the magmatism dykes faults and neoproterozoic metamorphic rock provide favorable advantages for the mineralization in donghua suggesting metallogenic potential

zircon u pb dating and sr nd pb hf isotopes of the ore associated porphyry at the giant donggebi mo deposit eastern tianshan nw china abstract the giant donggebi porphyry mo deposit is located in the jueluotage metallogenic belt of eastern tianshan xinjiang northwest china mo mineralization mainly occurs as numerous veinlets in the altered sandstone wall rocks with the development of potassic phyllic argillic and propylitic alteration assemblages outward from a buried porphyritic granite stock zircon crystals from the buried porphyritic granite yield a weighted average 206 pb 238 u age of 236 2 2 ma mswd 1 2 1 n 17 slightly older than the molybdenite re os isotope ages of 231 234 ma suggesting that the donggebi porphyry mo deposit was formed in the triassic post collisional tectonism subsequent to termination of the paleo asia ocean the samples from porphyritic granite show high contents of sio 2 k 2 o and al 2 o 3 low contents of tio 2 mgo and cao and peraluminous high k calc alkaline to shoshonite affinity with obvious lree enrichment and negative eu anomalies they have high initial 87 sr 86 sr ratios of 0 70618 to 0 70821 e nd t values of 0 60 to 1 62 and t dm2 nd ages of 0 88 to 0 96 ga their 206 pb 204 pb t 207 pb 204 pb t and 208 pb 204 pb t values are 17 122 18 577 15 493 15 574 and 37 887 38 006 respectively zircons from the porphyritic granite yield ehf t values of 1 58 to 4 82 and t dm2 hf ages of 0 96 1 36 ga these geochemical and isotopic data imply that the donggebi porphyritic granite originated mainly from partial melting of lower continental crust derived from a depleted mantle the donggebi mo deposit is unique based upon the crustal source for the causative porphyry the distal position of mineralization and the previously revealed co 2 rich ore forming fluids and thus belongs to the collisional or dabie type porphyry deposits as exemplified by the qiane chong and yaochong deposits in dabie shan the donggou deposit in qinling orogen china

hydrothermal water rock interaction and the redistribution of li b and cl in the taupo volcanic zone new zealand abstract lithium b and cl occur as trace elements in the dominant protoliths rhyolite andesite and greywacke underlying high temperature hydrothermal systems in the taupo volcanic zone tvz the fluid mobility of li decreases substantially at 200 c 20 c with the pervasive deposition of quartz chlorite regardless of protolith and altering fluid compositions boron and cl are more fluid mobile than li at all temperatures with mobility affected by the rock type composition of circulating aqueous solutions and to a limited extent by incorporation of the trace elements in hydrothermal minerals uptake of b by clays decreases its mobility at 320 c occur compared to volcanic rocks the mobility of b and cl in greywackes is very low and thus the b cl signature of greywacke in hydrothermal aqueous solutions of the tvz is overwhelmed by the effects of rhyolite and andesite dissolution temperature dependent transitions from mg fe clays and phyllosilicates to k bearing illitic clays tend to decrease the mg li ratios in aqueous solutions at 200 c

systematics of chlorite alteration at the phelps dodge massive sulfide deposit matagami quebec hydrothermal alteration at the phelps dodge archcan volcanogenic massive sulfide deposit has converted rhyodacite and rhyolite footwall rocks into the following mineral assemblages quartz chlorite albite epidote or sericite quartz chlorite or sericite chlorite or sericite and chlorite talc or stilpnomelane alteration at constant al was initiated by hydration addition of fe mg silicification and leaching of ca na which produced al saturated chlorites with a wide range of fe fe mg ratios within the assemblage quartz chlorite albite epidote or sericite with continued addition of fe and less mg combined with extensive leaching of quartz the chlorite became al undersaturated quartz chlorite talc assemblage and ultimately formed a rock composed essentially of chlorite the chlorite talc or stilpnomelane assemblage is stable in late crosscutting veinlets and in the ore zone chlorites in the si al mg fe system form a rectangular solid solution plane with limited substitution of al for si and extensive substitution of fe for mg in si al space the solid solution plane is outlined by al saturation presence of other al rich mineral and al undersaturation presence of al poor or al free mineral boundaries al iv substitution for si in the chlorites increases from 2 3 to 3 01 formula units based on 8 si al iv with fe fe mg whereas al iv occupancy decreases from 2 88 to 2 65 the valence charge balance is compensated by octahedral site vacancies or by the conversion of fe super 2 to fe super 3 the al iv content of chlorite also increases with temperature chlorites on the al saturated boundary of the solid solution field form a potentially useful geothermometer t degrees c 106 al iv 18 al iv is corrected for changes with the fe fe mg ratio as al iv corrected al iv 0 7 fe fe mg the fe fe mg ratios of bulk rock and contained chlorite correlate well birefringence colors of the chlorite change from green to brown violet and berlin blue as fe fe mg changes from 0 18 to 0 64 the fe fe mg variation apparently depends largely on the proportions of mg rich seawater and fe rich hydrothermal fluid in the altering brine

short wavelength infra red swir characteristics of hydrothermal alteration minerals in skarn deposits example from the jiguanzui cu au deposit eastern china abstract the jiguanzui cu au deposit is an important skarn deposit in the edong ore district of the middle lower yangtze river valley metallogenic belt mlyrb eastern china the mineralization occurred dominantly in the lower middle triassic jialingjiang formation marble either along interlayer fracture zones or along the intrusive contact with the early cretaceous quartz diorite based on the mineral assemblages and textural relationships the jiguanzui alteration mineralization can be divided into five stages namely i prograde skarn alteration garnet pyroxene ii retrograde alteration hornblende epidote actinolite iii hematite mineralization iv quartz sericite pyrite chalcopyrite mineralization main cu au mineralization stage and v calcite sulfide mineralization pyrite chalcopyrite molybdenite galena sphalerite systematic short wavelength infrared swir spectral analyses show that alteration minerals at jiguanzui include mainly sericite group minerals montmorillonite illite and muscovite kaolinite and carbonate minerals calcite ankerite and dolomite with minor chlorite halloysite and dickite spectral features of stage iv sericite group minerals indicate that the al oh absorption feature wavelength positions pos2200 have shifted toward longer wavelengths 2209 nm in the ore proximal area which may be caused by the substitution of fe and mg in the octahedral al site the vertical distance of mineralization indication can reach up to ca 450 m but can be affected by the wall rock lithology and the jiguanshan fault zone the fe oh absorption feature wavelength positions pos2250 of chlorite in the middle triassic puqi formation hornfels have also shifted toward longer wavelengths in the ore proximal area which may be caused by the relative mg rich nature of the chlorite we conclude that the high pos2200 2209 nm of sericite group minerals and the high pos2250 of chlorite can be used as prospecting tools for the jiguanzui cu au skarn mineralization

the adakite connection of the tuwu yandong copper porphyry belt eastern tianshan nw china trace element and sr nd pb isotope geochemistry the tuwu yandong porphyry copper belt lies in the eastern tianshan mountains eastern section of the central asian orogenic belt the copper mineralization is mainly hosted in plagiogranite porphyries intruded into early carboniferous volcanic rocks of the paleozoic dananhu island arc between the tarim and siberian plates the plagiogranite porphyries have contents of 65 73 wt sio2 14 17 wt al2o3 0 9 2 2 wt mgo 3 16 ppm y 0 4 1 40 ppm yb 347 920 ppm sr and positive eu anomalies the rocks also exhibit positive nd t values 5 0 to 9 4 and low initial 87sr 86sr values 0 70316 0 70378 such features are similar to those of adakites derived from partial melting of a subduction related oceanic slab the mineralization age is early carboniferous 350 320 ma which is close to that of the porphyries the close relationship between the cu mineralization and the porphyry is also indicated by their similar sr nd pb isotopic compositions we suggest that the copper porphyry magma system in the dananhu island arc was formed by direct melting of an obliquely subducting early carboniferous oceanic slab

a review of the cu ni sulphide deposits in the chinese tianshan and altay orogens xinjiang autonomous region nw china principal characteristics and ore forming processes abstract several cu ni sulphide deposits and occurrences have recently been discovered along parallel deep faults in the chinese tianshan and altay orogenic belts xinjiang province nw china the kalatongke and several other cu ni mineralized intrusions are located along the irtysh fault which separates the altay orogenic belt from the junggar basin the huangshan huangshandong xiangshan tudun erhongwa tula ergen and hongling deposits occur along the kanggurtag suture which separates the jueluotage orogenic belt from the turpan hami tuha basin the baishiquan tianyu and tianxiang deposits are located along the arqikekuduke fault which separates the jueluotage orogenic belt from the central tianshan precambrian terrane the poyi poshi and luodong deposits are located along the baidiwa fault which separates the central tianshan precambrian terrane from the beishan paleozoic rift re os dating of cu ni sulphide ores reveals that these cu ni ore belts formed in a narrow age range of 298 282 ma this age range is about the same as those of associated intrusions and dykes dated by the shrimp zircon u pb method tectonic and geochronological constraints suggest that the amalgamation of continental blocks mainly occurred during the late carboniferous in the central asian orogenic belt large scale hydrothermal and magmatic metallogenesis in the region occurred during post collisional stages of latest carboniferous to early permian age the cu ni sulphide deposits are part of this metallogenic event the cu ni orthomagmatic sulphide deposits in northern xinjiang are represented by 1 net textured type deposits by segregation of a cu ni metal sulphide melt and 2 magma conduit type some mafic ultramafic suites exhibit lithological zoning caused by strong differentiation stratiform orebodies are hosted by ultramafic rocks at the base of the magma chamber good examples are the kalatongke huangshandong and poshi deposits others such as the xiangshan baishiquan tianyu and tula ergen deposits are hosted by magma conduits consisting of peridotite troctolite and pyroxenite these ultramafic rocks either occur within faults or are surrounded by gabbroic and dioritic intrusions these two types of orthomagmatic cu ni sulphide deposits are also distributed along the same ore belts for instance the differentiated sill related huangshandong deposit co exists with the magma conduit type tula ergen deposit in the jueluotage orogenic belt orthomagmatic cu ni sulphide deposits in northern xinjiang formed during post collisional extension and are possibly related to a late carboniferous early permian mantle plume event the mafic ultramafic suites and associated cu ni deposits are commonly accompanied by dyke swarms and are characterized by elongated outcrops occurring along parallel e w trending regional faults these mafic ultramafic suites and accompanying dyke swarms are generally fractionated implying that they were feeders of presently eroded flood basalts

geochemical sm nd isotopic characteristics and petrogenesis of paleoproterozoic mafic rocks from the georgetown inlier north queensland implications for relationship with the broken hill and mount isa eastern succession fe rich tholeiites intruded the lower etheridge group of the georgetown inlier north queensland during the late paleoproterozoic ca 1685 1640 ma emplacement of the tholeiites occurred during a prolonged period of rift related sedimentation associated with extension the tholeiites comprise two lithologically distinct units the extrusive dead horse metabasalt dhm a conformable 1000 m thick series of fine to coarse grained basalts and pillow lavas and the intrusive cobbold metadolerite cmd a multitude of sills and lesser dykes that range up to 500 m thick the dhm and cmd are comagmatic and have compositions typical of relatively evolved low k fe rich continental rift tholeiites immobile major and trace element patterns suggest that the tholeiites were derived from a depleted upper mantle source initial nd values range between 2 6 and 5 3 the parental melts evolved along a trend of increasing fe enrichment fe2o3 6 81 21 11 wt via closed system fractionation with little or no replenishment several samples show distinct ree patterns consistent with limited crustal contamination trace element and isotopic data show that the crustal contaminants were derived from the host metasediments of the lower etheridge group the age and geochemical characteristics of the etheridge group fe rich tholeiites show striking similarities to similar mafic sills in the southeastern curnamona province around broken hill in western new south wales and to basaltic lavas and dolerites of the soldiers gap group in the eastern edge of the mt isa block some 400 km west of the georgetown inlier suggesting a spatial link between these terranes during the paleoproterozoic they may have formed along a more than 2000 km segment of a ca 1685 1640 ma volcanic passive margin tectonically and magmatically akin to the modern east greenland margin

trenching exposures of the surface rupture of 2008 mw 7 9 wenchuan earthquake china implications for coseismic deformation and paleoseismology along the central longmen shan thrust fault abstract the may 12 2008 mw 7 9 wenchuan earthquake was induced by failure of two of the major faults of the longmen shan thrust fault zone along the eastern margin of tibet plateau our study focused on trenches across the yingxiu bichuan fault the central fault in the longmen shan belt that has a coseismic surface break of more than 200 km long trenching excavation across the 2008 earthquake rupture on three representative sites reveals the styles and amounts of the deformation and paleoseismicity along the longmen shan fault styles of coseismic deformation along the 2008 earthquake rupture at these three sites represent three models of deformation along a thrust fault two of the three trench exposures reveal one pre 2008 earthquake event which is coincident with the pre existing scarps based on the observation of exposed stratigraphy and structures in the trenches and the geomorphic expressions on ground surface we interpret the 2008 earthquake as a characteristic earthquake along this fault the interval of reoccurrence of large earthquake events on the central longmen shan fault the yingxiu beichuan fault can be inferred to be about 11 000 years according to 14c and osl dating the amounts of the vertical displacement and shortening across the surface rupture during the 2008 earthquake are determined to be 1 0 2 8 m and 0 15 1 32 m respectively the shortening rate and uplift rate are then estimated to be 0 09 0 12 mm yr and 0 18 0 2 mm yr respectively it is indicated that the deformation is absorbed mainly not by shortening but by uplift along the rupture during the 2008 earthquake

hydrothermal alteration fluid inclusions and stable isotope characteristics of the shaquanzi fe cu deposit eastern tianshan implications for deposit type and metallogenesis abstract the shaquanzi fe cu deposit is an important fe cu deposit in the yamansu fe mineralization belt eastern tianshan five stage stage i to v hydrothermal alteration mineralization have been recognized the early skarn stage i and late skarn stage ii stages are featured by extensive garnet and amphibole alteration respectively magnetite mineralization stage stage iii is associated with pervasive k fe ca alteration forming magnetite mushketovite k feldspar epidote magnetite pyrite and quartz chalcopyrite mineralization stage stage iv has an ore mineral assemblage of chalcopyrite bornite acicular hematite and sphalerite accompanied with broad epidote chlorite calcite alteration the late veins stage stage v occurs mainly as epidote calcite veins crosscutting the host rocks and earlier stage minerals stage i hydrothermal fluids have high temperatures 600 c medium high salinities with magmatic 18ofluid 6 to 11 7 stage iii ore forming fluids are medium high temperature ca 470 570 c with medium salinity stage iii minerals were formed under dfluid 45 7 to 24 3 18ofluid 5 8 to 9 1 and 34sfluid 1 7 to 4 7 indicative of magmatic fluids mixed with minor seawater in contrast stage iv fluids have low temperatures ca 160 c medium low salinities and are ca rich with isotopic compositions reflecting basinal brine mixed with meteoric water 13cfluid 6 6 to 2 3 18ofluid 3 3 to 2 8 and 34sfluid 24 8 the shaquanzi diorite zircon u pb age 298 5 ma is broadly coeval with previous re os ages of the shaquanzi magnetite and pyrite 303 12 ma and 295 7 ma respectively indicating that the shaquanzi fe cu metallogeny may have been genetically linked to the regional magmatic hydrothermal activities led by the yamansu arc backarc basin inversion features of hydrothermal alterations mineral assemblages ore forming fluids and tectonic setting all suggest that the shaquanzi fe cu deposit is an iocg like deposit similar to those in the cenozoic central andes

overprinting mineralization in the paleozoic yandong porphyry copper deposit eastern tianshan nw china evidence from geology fluid inclusions and geochronology abstract the yandong porphyry copper deposit is located in the southern part of the dananhu tousuquan island arc belt in eastern tianshan xinjiang nw china the dananhu tousuquan belt contains a number of large and medium cu deposits among which the yandong deposit 2 0 mt cu 0 67 is the largest the yandong cu deposit is hosted by plagiogranite porphyry and the carboniferous qi eshan group mafic to intermediate calc alkaline volcanic and pyroclastic rocks according to the crosscutting relationships and mineral assemblages the alteration and mineralization processes at yandong comprise three episodes the porphyry mineralization episode including potassic propylitic early phyllic and late phyllic stages the overprinting mineralization episode including main and post mineralization stages and lastly supergene alteration episode fluid inclusions fis in quartz from the potassic early late phyllic and post mineralization stages and anhydrite from the main post mineralization stages include four types 1 vapor liquid two phases w type 2 daughter mineral bearing s type 3 pure liquid pw type and 4 pure vapor pv type the potassic stage contains w s and pv type fis which yielded homogenization temperatures of 304 445 c mainly 340 400 c and salinities of 3 1 16 4 mainly 4 0 10 0 wt nacl eqv at the early phyllic stage three types of fis are identified i e the w s and pv type the s type and w type fis homogenized at 213 441 c mainly 280 300 c and 241 352 c mainly 300 320 c respectively with corresponding salinities of 33 1 52 0 mainly 34 0 40 0 wt nacl eqv and 0 9 15 9 mainly 0 9 4 0 wt nacl eqv respectively the late phyllic stage contains w s and pw type fis which homogenized at 146 248 c mainly 160 180 c with salinities ranging from 3 9 to 18 2 mainly 4 0 8 0 wt nacl eqv mineralization depths calculated from fis are 0 8 1 2 km stage i 0 6 1 8 km stage iiia and 0 4 0 7 km stage iiib fluid boiling and mixing likely occurred during the porphyry mineralization period leading to the precipitation of pyrite and chalcopyrite during the overprinting mineralization the w and pv type fis occur in the main mineralization anhydrite with homogenization temperatures and salinities being 248 421 c mainly 300 340 c and 5 3 13 8 mainly 8 0 10 0 wt nacl eqv respectively the post mineralization quartz and anhydrite homogenized at 105 195 c mainly 120 140 c with salinities of 0 5 13 6 mainly 8 0 10 0 wt nacl eqv the ore forming fluids may have predominantly been entrapped at 0 8 1 6 km stage iv and 0 3 0 6 km stage v the decreasing temperature may have led to the sulfides and sulfate precipitation and enrichment sericite 40 ar 39 ar dating of the altered plagiogranite porphyry yielded a plateau age of 332 8 3 8 ma consistent with the age of the early ore forming plagiogranite porphyry 339 332 ma re os dating of molybdenite coexisting with chalcopyrite anhydrite chlorite calcite assemblage yielded an age of 324 3 2 7 ma weighted mean consistent with the late quartz albite porphyry age zircon u pb 323 6 2 5 ma consequently we propose that at least two mineralization episodes may have occurred at yandong with the second episode contributing to the majority of the cu mo resources such overprinting mineralization style at yandong may represent a good example of the paleozoic cu deposits in the central asian orogenic belt

genesis of the yandong porphyry cu deposit in eastern tianshan nw china evidence from geology fluid inclusions and isotope systematics abstract the yandong porphyry cu deposit 372 mt at 0 58 cu is located in the center of the eastern tianshan xinjiang nw china multiple stage hydrothermal activities have resulted in potassic chlorite sericite phyllic and propylitic alteration in this deposit the yandong deposit formed in four stages i e an early quartz magnetite pyrite stage i a quartz pyrite chalcopyrite stage ii a quartz chalcopyrite pyrite molybdenite stage iii and a late quartz carbonate stage iv three evolutionary episodes were observed by a detailed fluid inclusion study 1 early ore stage i fluids were trapped under two phase conditions as evidenced by the coexistence of vapor rich v type inclusions homogenization temperatures 410 494 c average salinity 2 2 wt nacl equiv liquid rich l type inclusions homogenization temperatures 311 430 c average salinity 9 5 wt nacl equiv and hypersaline h type inclusions trapped at 300 bars or a depth of approximately 1 km assuming lithostatic pressure conditions 2 main ore stage ii and iii fluid inclusions in quartz were also trapped under two phase conditions boiling as identified by the coexistence of v and l type fluid inclusions l type inclusions homogenized between 161 and 390 c average 270 c with salinities of 1 6 9 9 wt nacl equiv average 4 9 wt nacl equiv and a depth of 1 km 100 bars hydrostatic pressure conditions 3 late ore stage iv fluids are represented by inclusions in barren quartz carbonate veinlets characterized by homogenization temperatures ranging from 123 to 261 c average 179 c and salinities between 0 7 and 4 7 wt nacl equiv average 2 0 wt nacl equiv the initial hydrothermal fluids are characterized by high temperature high salinity and high oxygen fugacity belonging to a h 2 o nacl system hydrogen and oxygen isotope data indicate that the hydrothermal fluids have a dominantly magmatic signature and mixed with abundant meteoric waters in the quartz carbonate stage sulfur stable isotope suggests that the ore forming metals came primarily from the tonalite magma that sourced from the subducted oceanic slab involving some mantle peridotites during ascent the cu mineralization of the yandong porphyry deposit occurred at a shallow crustal level approximately 1 km and the fluid boiling or phase separation decrease of temperature as well as fluid rock interaction were likely important factors responsible for metal accumulation and deposition in the magmatic hydrothermal system

gas geochemistry as a tool to investigate the earth s degassing through volcanic and seismic areas the soul of the 8th international conference on gas geochemistry

yandong porphyry cu deposit xinjiang china geology geochemistry and sims u pb zircon geochronology of host porphyries and associated alteration and mineralization abstract the yandong porphyry copper deposit located in the eastern tianshan mountains xinjiang china is part of the central asian orogenic belt the yandong deposit is hosted by a volcanic complex in the early carboniferous qi eshan group and a felsic intrusion the complex consists of andesite basalt diorite porphyry and porphyritic quartz diorite the felsic intrusion is a plagiogranite porphyry emplaced within the complex the diorite porphyry and plagiogranite porphyry yield sims zircon u pb ages of 340 0 3 and 332 2 2 3 ma respectively element geochemistry shows that both the complex and plagiogranite porphyry formed in the dananhu tousuquan island arc a carboniferous magmatic arc the diorite porphyry and plagiogranite porphyry are host porphyries but the plagiogranite porphyry is a productive porphyry it caused the porphyry style cu mineralization and associated alteration the alteration assemblages include early potassic and propylitic assemblages these were overprinted by a chlorite sericite assemblage which in turn was overprinted by a late phyllic assemblage the phyllic alteration is associated with the highest cu grades the mineralization is recognized to include three stages from early to late stage 1 a potassic alteration associated with a chalcopyrite pyrite assemblage stage 2 represented by chlorite sericite alteration with a chalcopyrite pyrite assemblage and stage 3 the main ore stage that is marked by phyllic alteration with chalcopyrite pyrite molybdenite and producing more than 70 of the total copper production at yandong yandong may represent a common scenario for paleozoic porphyry cu systems in the central asian orogenic belt

architecture of basin mountain systems and their influences on gas distribution a case study from the sichuan basin south china abstract the basin mountain systems in the sichuan basin exert major control on today s oil gas distribution chiefly through their controlling influence on petroleum reservoirs preservation the thickness of deposited terrestrial formations and degree of uplift and denudation the composite basin mountain system in the sichuan basin and its peripheral mountains can be classified as two types margin plate systems and interior plate systems the margin plate basin mountain systems include the sichuan basin and its surrounding longmen mountains micang mountains and daba mountains which are not only the western and northern marginal area of the sichuan basin but also represent the western margin of the yangtze plate south china block the margin plate basin mountain systems with binary units of large scale thrust belts and foreland basins have different deep lithospheric structures abrupt boundaries and great contrast in today s geomorphology between the basin and the mountains on the contrary the interior plate basin mountain systems comprised by the sichuan basin and its adjacent interior plate qiyue mountains dalou mountains and daliang mountains represent the eastern and southern marginal area of the sichuan basin located within the yangtze plate they have similar lithospheric structure and gradual boundaries between the basin and the adjacent mountains lacking foreland basins today s medium large scale natural gas accumulations in the sichuan basin are mainly distributed in the areas influenced by the margin plate basin mountain systems and are located especially in the foreland basins

petrology and geochemistry of propylitic alteration at southwest tintic utah systematic variations in mineral assemblages fluid inclusion characteristics mineral chemistry and isotopic ratios document the chemical and thermal evolution of hydrothermal fluids responsible for late alteration in a small porphyry copper system near tintic utah propylitic alteration of volcanic rock can be subdivided into actinolite epidote and chlorite subzones an actinolite subzone containing actinolite epidote chlorite and calcite extends 250 m away from the secondary biotite zone an epidote subzone containing epidote chlorite and calcite is present up to 500 m away from the secondary biotite zone a chlorite subzone of chlorite and calcite is present up to 2 km from the secondary biotite zone chlorite which occurs in each subzone varies systematically in fe mg and mn content the ratio fe fe mg increases from 0 27 at the secondary biotite zone to 0 48 in the outer propylitic zone accompanied by a decrease in activity of clinochlore from 0 15 to 0 02 mno increases from 0 23 to 0 44 wt percent the fe super 3 content of epidote also systematically decreases from the actinolite subzone outward the activity of clinozoisite in the epidote ranges from 0 038 at the secondary biotite zone to 0 21 700 m away from the secondary biotite zone in the outer epidote subzone systematic changes in chlorite and epidote compositions reflect increasing log a sub mg super 2 a 2 sub h super and log a sub fe super 2 a 2 sub h super with increasing distance from the hydrothermal biotite zone and decreasing temperature and salinity fluid inclusion homogenization temperatures decrease away from the secondary biotite zone with a horizontal thermal gradient of 78 degrees c km temperatures range from 351 degrees to 160 degrees c in propylitic alteration salinities also decrease outward from 7 3 to 0 0 equiv wt percent nacl hydrothermally altered rocks are systematically depleted in 18 o outward from the phyllic alteration zone into the chlorite subzone as recorded by whole rock samples 10 9 to 1 7ppm calcite 10 4 1 6ppm and quartz veins 2 8 to 0 8ppm calculated delta 18 o and delta d values for the actinolite subzone are 5 and 55 per mil respectively values as low as 15 1 and 120 per mil are recorded at the outer limits of sampling in the chlorite subzone these latter values indicate that outer propylitic alteration is dominated by isotopically unevolved local meteoric water however the large variations in hydrogen and oxygen isotope compositions recorded across the zoned propylitic alteration are too large to have been produced from an isotopically homogeneous fluid given the measured range of alteration temperatures 350 degrees 200 degrees c rather the variations in isotopic compositions and salinity of the propylitic alteration fluids are consistent with the progressive mixture of unevolved 18 o and d depleted low salinity local meteoric water with a much more 18 o and d enriched higher salinity fluid the later phyllic alteration also formed from a similar 18 o and d enriched fluid we suggest that these isotopically enriched fluids more likely evolved from local meteoric water through extensive exchange at very low water rock ratios with the igneous rocks at depth in the hydrothermal system at tintic an alternative explanation is that 18 o and d enriched fluids represent a late incursion of magmatic water unlike many other porphyry copper systems participation of such 18 o and d enriched fluids in the waning stages of hydrothermal alteration at tintic contrasts with the usual domination of isotopically unevolved meteoric water at these stages e g propylitic phyllic in many porphyry copper systems sheppard et al 1971 taylor 1974 gustafson 1978 at tintic isotopically enriched fluids coexist with and even displace meteoric water during propylitic and phyllic alteration respectively

geological characteristics and genesis of the tuwu porphyry copper deposit hami xinjiang central asia abstract the tuwu copper deposit located in the dananhu tousuquan island arc between the kazakhstan junggar and tarim plates is one of the largest porphyry copper deposits in western china ore hosting rocks consist of early carboniferous 333 2 ma granodiorite and plagiogranite porphyries both the porphyries are elongate the orebodies consisting of veinlet disseminated mineralization within the porphyries grade range from 0 30 to 1 50 cu mineralization can be assigned to six stages wall rock alteration associated with the mineralization include silicification chloritization epidotization sericitization and carbonatization three alteration zones have been recognized phyllic zone chlorite biotite zone and propylitic zone re os dating indicates a 322 7 3 ma age for the deposit 34 s values of the ore sulfides range from 0 9 to 1 3 with a mean of 0 11 reflecting a deep sulfur source 18 o values of quartz in the ores range from 7 70 to 9 70 and the 18 o value of chlorite in the ores is 6 62 calculated 18 o water values of quartz and chlorite range from 5 37 to 6 62 and the d values range from 48 to 63 suggesting that the ore fluids were mainly magma derived in the early stage of mineralization however values for the late mineralization stage decrease suggesting the addition of meteoric waters during the mineralization fluid inclusions within quartz grains are generally 3 to 30 m in size with gas proportions ranging from 5 to 60 mostly from 10 to 15 homogenization temperatures of fluid inclusions are relatively low bracketed between 101 and 409 c mostly between 100 and 200 c salinities exhibit a wide range from 0 35 to 14 61 wt nacl equiv with a mean of 7 72 wt nacl equiv suggesting that ore fluids have low to moderate salinity the ore bearing plagiogranite porphyries show a strong depletion in heavy rare earth elements with average values of yb and y of 0 65 and 5 90 ppm respectively this being a characteristic geochemical signature for adakite the geochemical signature of the adakites within the granitoid rocks represents a characteristic guide for further exploration for copper porphyry type ore deposit in eastern tianshan

evidence for nondiffusive transport of 86rn in the ground and a new physical model for the transport concentration of radon has been measured in the soil near the ground surface with solid state nuclear track detectors with the inverted cup technique measurements were made in the overburden at depth intervals 0 1 0 7 m at 0 1 6 m and at a constant depth of 0 2 m in a narrow rectangular matrix the results disagree with the hypothesis that radon concentration only depends upon local production and migration by diffusion with a diffusion length of about 1 m a transport length of 0 1 0 2 m is observed near the ground surface and the transport is dominated by a flow component radon measurements in the ground surface over the laisvall lead mine have given evidence of radon transport through rock exceeding a distance of 100 m which is possible only if the migration is a flow transport with a characteristic transport length larger than about 10 m day to explain the radon transport in the overburden and through the rock with a common transport system the existence of a general upward flow of geo gas is

subsoil co2 and ch4 and their advective transfer from faulted grassland to the atmosphere measurements of co2 and ch4 in 3 m deep groundwater soil gas and soil atmosphere fluxes were completed in two grasslands in central italy having the same soil conditions but different subsoil fault linked secondary permeability unfaulted grassland displays gas phase equilibrium between soil air and groundwater typical soil gas diffusion profiles and diffusive soil to atmosphere gas transfer on the basis of oxygen depletion assessment assuming a ratio of 1 1 between biogenic o2 consumption and co2 production the measured soil co2 concentrations are consistent with a normal production in the soil by biologic activity the faulted grassland instead has higher co2 and ch4 concentrations up to 6 and 10 ppmv in soil air and flux 1 2 ml m 2 s 1 and 1 3 l m 2 s 1 resulting from a combination of soil biologic and endogenous components with evidence of gas transfer from the saturated to the unsaturated zone and advective gas transfer from soil to the atmosphere the extra soil source in the faulted zone which is about 0 3 4 times the background soil biologic production is likely related to migrating crustal gas whatever the c gas origin and depth may be biogenic or abiogenic shallow or deep the present results demonstrate that the subsoil derived component occurring in the soil in areas with active tectonics cannot be ignored a priori in the assessment of the c terrestrial sources in particular the assumption that dryland soils are sinks for methane owing to methanotrophic consumption may be not true in areas affected by active and gas bearing faults accordingly it would be very important to assess at global scale the actual role in the carbon dioxide and methane cycle of soils within the active tectonic bounds

paleozoic accretionary and collisional tectonics of the eastern tianshan china implications for the continental growth of central asia this paper deals with the various tectonic units in the chinese eastern tianshan orogenic collage in the central asian orogenic belt and discusses the paleozoic geological history of the several periods of accretion and collision of archipelago systems lying between the tarim and southern angaran continental margins the late ordovician silurian to early devonian eastern tianshan archipelago was characterized by a the harlik dananhu subduction system with a s dipping polarity in the north b a southerly n dipping subduction system beneath the central tianshan arc in the middle and c the south tianshan ocean against tarim in the south during the devonian to early carboniferous n dipping subduction led to the harlik dananhu arc and the kanggurtag forearc basin accretionary complex in the early to mid carboniferous the magmatic front associated with the n dipping subduction beneath the dananhu harlik arc migrated southwards forming the yamansu arc constructed upon the kanggurtag accretionary forearc by the late carboniferous the dananhu harlik arc was attached northwards to the angaran margin resulting in lateral enlargement of the angaran continent in the latest carboniferous to early permian a multiple soft collision left wide suture zones in the south that include the ophiolite strewn aqikkuduk shaquanzi and kumishi accretion collision complexes which were stitched by early permian post collisional plutons by re defining and re interpreting the various tectonic terranes this paper presents a new improved model for the paleozoic evolution of this part of central asia

recognizing propylitic alteration associated with porphyry cu mo deposits in lower greenschist facies metamorphic terrain of the collahuasi district northern chile implications of petrographic and carbon isotope relationships the collahuasi district is a porphyry cu mo subprovince located on the andean high plateau of northern chile late eocene early oligocene mineralization in the district involved hydrothermal alteration of the upper paleozoic to lower triassic collahuasi group granodiorites diorites andesites dacites and rhyolites which had previously experienced regional lower greenschist facies metamorphism as well as uneconomic porphyry style mineralization and associated sericitic alteration alteration mapping represents an effective technique for prospecting for hydrothermal deposits but in low grade metamorphic terrains recognition of propylitic assemblages that represent the boundary of the mineralizing system is hampered by their resemblance to metamorphic mineral assemblages our results from collahuasi indicate that petrographic criteria can distinguish propylitic alteration from the effects of lower greenschist facies metamorphism but distinctions vary with rock type mafic intermediate and felsic rocks with varying degrees of propylitic alteration can be distinguished from background metamorphism mainly by the presence of calcite however propylitic alteration can also be distinguished by high whole rock 13c values and carbon contents 19 1 to 1 4 and up to 0 79 wt respectively that result from the incorporation of magmatic co2 during the mineralizing events lower 13c values 32 7 to 13 1 and carbon contents 0 09 wt were recorded in other types of hydrothermal alteration intermediate argillic sericitic and potassic alteration and associated with background metamorphism they reflect a dominantly 13c depleted carbon component that remains in the rocks after extensive co2 degassing during emplacement alteration by hydrothermal fluids or contamination by organic carbon carbon and oxygen isotope compositions of calcite from propylitic alteration which range from 12 to 0 3 and 6 6 to 25 9 respectively are consistent with a predominantly magmatic origin for the carbonates although subsequent resetting of the oxygen isotopes by local ground water and minor contributions of organic carbon are recorded in some samples spatial variation in 13c values and carbon contents of outcrop samples from the collahuasi district delineate zones of high magmatic co2 component that correspond exclusively to propylitic alteration surrounding economic deposits

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

radiolaria as indicators of upwelling processes the peruvian connection abstract in the sediments along the coastal region of peru certain radiolarian species have preferences to waters associated with upwelling such is the case forpolysolenia murrayana in the upwelling areas fed by equatorial water and forcenosphaera sp in the upwelling areas fed by temperate subantarctic water cycladophora davisiana appears to frame the upwelling centers suggesting that it prefers regions near thermic fronts the down core records of these species as well as records of quartz and organic carbon are depicted in three14c and 18o dated cores located along the pacific coast of south america between 11 and 13 s they suggest that both the eolian and oceanic circulation were more intense during the last glacial stage approximately between 33 000 and 11 000 years ago than during the present postglacial at these latitudes the intensification in circulation was not only accompanied by an increased coastal upwelling and in turn by an increased primary productivity but also by a larger supply of temperate waters to the area

chlorite as an exploration indicator for concealed skarn mineralization perspective from the tonglushan cu au fe skarn deposit eastern china abstract compositional variations of chlorite have been increasingly used to trace the magmatic hydrothermal fluid evolution as well as exploration vector toward concealed orebodies this method has been widely applied to porphyry cu au systems but related research on skarn systems remain scarce the tonglushan cu au fe deposit 86 3 mt 1 66 cu 0 94 g t au and 39 4 fe is one of the largest cu au polymetallic skarn deposits in the middle lower yangtze river metallogenic belt mlyrb eastern china based on detailed petrographic observation we present new epma and la icp ms elemental data for the tonglushan chlorite and discuss their implications on hydrothermal fluid evolution and exploration of concealed skarn orebodies there at tonglushan chlorite alteration is well developed in the main cu au sulfide ore stage three types of chlorite have been identified i e disseminated chlorite replacing biotite and or hornblende in the ore causative quartz monzodiorite porphyry vein type chlorite in quartz chlorite sulfides veins along near the internal and external intrusive contact and replacement type chlorite that replaced garnet diopside epidote and fe oxides in the skarn mineralization center all the tonglushan chlorite samples belong to trioctahedral chlorite and have similar crystallization temperatures 163 351 c the substitution mechanisms of fe2 mg2 tschermark alivalvi si mg2 fe2 and di trioctahedral 3 mg2 fe2 2alvi are likely important for the tonglushan chlorite formation replacement type chlorite shows higher contents of feot mobile elements e g ca na b sr pb zn and sn and ore forming elements e g cu and co whereas the disseminated chlorite has higher contents of ti li liles e g k rb ba and cs and incompatible elements e g v sc co and ni meanwhile the vein type chlorite has similarly high contents of ti li v sc and ni to the disseminated chlorite but has higher feot and cu contents but lower mgo content than the latter such compositional differences may have mainly attributed to the protolith or precursor minerals and hydrothermal fluid chemistry integrating the chlorite petrographic features and chemical compositions we suggest that elevated feot and b contents and fe fe mg ratios and lower mgo al2o3 ti v and sc contents can serve as proximal indicator for exploring concealed skarn orebodies at tonglushan as well as other similar cu au fe skarn deposits in the mlyrb

ore geology and fluid evolution of the giant caixiashan carbonate hosted zn pb deposit in the eastern tianshan nw china abstract the caixiashan giant carbonate hosted zn pb deposit 131 mt 3 95 zn pb formed by replacement of dolomitized marble with stratiform massive and breccia bodies is located near the base of the proterozoic kawabulake group limestone and marble it is one of the largest carbonated hosted massive sulfides zn pb ore deposits in northwest china to have been discovered in recent years abundant pyrite occurs in dolomitized marble along fractures in dolomitized clasts in the host rocks and filling cracks in the host rock locally colloform or framboidal pyrites are observed in the early period and sometimes replaced by the later sphalerite the sulfide assemblage of the main ore stage is characterized by massive or disseminated sphalerite and galena with less pyrite than the earlier stage and minor pyrrhotite galena occurs as small veins cutting the early formed sphalerite dolomite and calcite are the main gangue minerals that co precipitated with these sulfides tremolite and quartz alteration commonly overprints the orebodies according to the crosscutting relationships and the different mineral associations within the host rocks and ore bodies three stages are recognized at caixiashan i e syn sedimentary pyrite stage i pyrite alteration sphalerite carbonate and galena pyrite carbonate stage ii 1 stage ii 2 and stage ii 3 respectively and magmatic metamorphic reworking stage iii calcite and quartz crystals are important host minerals among the three hypogene stages stages i iii although quartz mainly occurred in stage iii stage i contains only aqueous inclusions w type which were homogenized from 110 to 236 c main range of 138 198 c and average at 168 c main range average and the salinities are from 0 5 to 16 5 main range of 5 1 15 1 with average of 10 1 wt nacl eqv in the pyrite alteration of stage ii 1 the w type fluid inclusions homogenized from 175 to 260 c main range of 210 260 with average of 235 and the salinities range from 8 5 to 22 4 main range of 16 7 20 1 with average of 18 4 wt nacl eqv in the main zn pb mineralization stage stage ii 2 3 four types of fluid inclusions were identified an aqueous phase w type a pure carbon phase pc type a carbon phase containing c type and mineral bearing inclusions s type the w type fluid inclusions of stage ii 2 3 homogenized at 210 to 370 c main range of 253 323 and average at 270 and the salinities range from 5 9 to 23 1 main range of 13 3 20 3 with average at 16 8 wt nacl eqv c type homogenized at 237 c to 371 c and the salinities range from 6 4 19 7 wt nacl eqv s type fluid inclusions homogenized at 211 to 350 c and daughter minerals melted between 340 and 374 c during heating indicating a salinity range of 42 to 44 wt nacl eqv pc type fluid inclusions with homogenization temperatures of co 2 phase show large variation from 7 4 c to 21 2 c laser raman analyses show that ch 4 co 2 and so 4 2 coexist in the main mineralization stage fluids the magmatic metamorphic reworking stage only contains w type fluid inclusions which yield homogenized between 220 and 360 c main range of 251 325 and average at 288 with salinities ranging from 1 7 to 23 0 main range of 14 3 20 0 and average at 18 8 wt nacl eqv the textural features mineral assemblages and fluid geochemistry suggest that the zn pb ores were formed through hydrothermal convection of hot marine waters along the faults and fractures resulting in metal zn pb and fe enriched stratiform orebodies subsequent rapid precipitation of sulfides was triggered by sulfate so 4 2 thermal reduction with the ch 4 preserved in sedimentary rocks and early stage i pyrite bodies this process occurred at moderate temperatures ca 270 c higher temperature magmatic hydrothermal alteration overprinted the orebodies but only provided a minor contribution to the mineralization

element transport and enrichment during propylitic alteration in paleozoic porphyry cu mineralization systems insights from chlorite chemistry abstract chlorite is one of the most widely developed minerals in propylitic alteration around porphyry deposits and can be used to investigate element transport and enrichment processes during hydrothermal alteration the paleozoic tuwu porphyry cu deposit metal reserve 0 7 mt cu 0 67 located in the southern margin of the central asian orogenic belt is one of the most economical and largest porphyry cu deposits in nw china the tuwu porphyry cu deposit comprises an early porphyry cu mineralization including potassic propylitic and phyllic alteration stages and later overprinting cu mineralization periods with chlorite found in both chlorite from the propylitic zone at tuwu is geochemically similar to propylitic chlorite in younger cenozoic porphyry systems but enriched in mg and k and depleted in fe and al relative to the overprinting chlorite scandium v ti and ga are enriched and li sr mn and zn are depleted in the tuwu propylitic chlorite proximal to the orebody consistent with cenozoic deposits compared with metamorphic chlorite from proterozoic metamorphic terranes in australia tuwu propylitic chlorite has higher mg and k lower fe al and as our results suggest propylitic alteration in the tuwu district is probably the product of cooling of fluids derived from the magmatic hydrothermal system but not from peripheral waters and trace element variations in chlorite are mainly controlled by temperature although other factors such as fault development could affect variation trends the common elemental features of chlorite in both paleozoic and cenozoic porphyry cu deposits indicate it could act as a potential tool for mineral exploration

elemental behavior during chlorite alteration new insights from a combined empa and la icpms study in porphyry cu systems abstract chlorite is a common alteration product of fluid rock interaction in hydrothermal deposits and it s compositional variations provides useful information about the physicochemical conditions of formation but element behavior during the chloritization process is still not well understood chlorite from two large porphyry cu deposits atlas philippines and xiaokelehe ne china have been chosen to evaluate the geochemical variations with a focus on mass transfer during alteration of precursor minerals conversion of two biotite to one chlorite is the main mechanism for the chloritization of biotite iron mg al and ni are mostly retained in chlorite whereas co ga mn and zn are commonly transferred to chlorite from the hydrothermal fluid and sc sr si v li k nb ba rb ti cl na sn and cu from the biotite mostly do not enter chlorite during chloritization chlorite alteration of hornblende formed probably through the processes of dissolution precipitation iron are mostly retained in the chlorite whereas li cu ni zn co al and ga in the chlorite are at least in part derived from hydrothermal fluid and mg mn v si ca zr nb sn cl ree y na ti sr k sc and ba originally in the hornblende mostly enter hydrothermal fluid titanite or epidote rather than chlorite during chloritization the mgo feot mno zn li sc v co and ni concentrations and feot mgo ratio of chlorite are strongly influenced by those of the precursor minerals moreover although formed in the same porphyry system the mno zn li and cu concentrations and feot mgo ratios of chlorite formed from biotite and hornblende are markedly different given that fe mg ratios of chlorite are controlled by the precursor minerals in wall rock the fe fe mg correction on the well established chlorite thermometers during hydrothermal alteration may need to be reconsidered aluminum ga and ti in chlorite are not controlled by precursor minerals but by formation temperature of chlorite so we can use these elements of chlorite to map out the thermal structure of porphyry system which is related to individual mineralized porphyry intrusion which can help to identify the centers of hydrothermal systems

chlorite chemistry of tongshankou porphyry related cu mo w skarn deposit eastern china implications for hydrothermal fluid evolution and exploration vectoring to concealed orebodies abstract recent years the depletion of shallow mineral resources has drawn increasing attention to the exploration of hidden ore bodies in deep of skarn type deposits chemical composition of chlorite is an effective tool for tracing the hydrothermal fluid evolution and has been increasingly used for deep level exploration of porphyry cu au deposits pcds however the technique was rarely applied onto porphyry related skarn deposits the tongshankou cu mo w deposit 0 55 mt cu 0 86 0 01 mt mo 0 10 and 0 12 mt wo3 0 19 is one of the largest skarn porphyry deposits in the middle lower yangtze river metallogenic belt mlyrb in eastern china in this study new petrographic and trace element data of the hydrothermal chlorites from tongshankou were presented to constrain the ore fluid evolution and to explore the vectoring potential of the concealed orebodies at tongshankou four types of chlorite have been identified i e g type chlorite that replaced the original magmatic biotite or hornblende v type chlorite in chlorite quartz sulfides veins in the granodiorite porphyry alteration zones i and ii s type chlorite that replaced garnet in the intensive skarn alteration zone iii and m type chlorite quartz calcite sulfides veins that cut the dolomitic marble in the distal alteration zones iv and v all the four types of chlorites are typically trioctahedral chlorite the fe mg tschermark and di trioctahedral substitution mechanisms likely control the geochemical variations of the tongshankou chlorites empirical thermometer indicates that the tongshankou chlorites were crystallized at 169 322 compared with typical metamorphic chlorites the higher zn and sr contents but lower al content in the tongshankou chlorites can potentially distinguish the skarn type hydrothermal chlorites from typical metamorphic ones compared with the chlorites in the typical pcds the tongshankou g type chlorite has higher fe zn as and sn contents but lower al mg co and cu contents which likely reflect its protolithic and or fluid geochemical inheritance the tongshankou v m and s type chlorites have high contents of mobile elements such as sr ca sn and b and metals such as fe cu as zn and pb indicating that they were directly precipitated from the hydrothermal fluids from the granodiorite porphyry to the marble wallrocks the spatial chlorite geochemical variations at tongshankou indicate that the increasing zn mn ga ge and pb contents and decreasing v sc and ti contents are potential vectors toward concealed mineralized porphyries at tongshankou our study highlights that the chlorite geochemistry is a potential tool for ore fluid tracer and vectoring tool toward concealed skarn porphyry orebodies in the mlyrb

geochronology geochemistry and petrogenesis of early permian alkaline magmatism in the eastern tianshan implications for tectonics of the southern altaids abstract in the early permian large volumes of volcanic rocks developed in the eastern tianshan of the southern altaids the shaerhu alkaline complex which occurs along a nw trending transcurrent fault in the dananhu arc is composed of alkaline gabbro intrusions granites and rhyolites the gabbros and rhyolites have similar zircon crystallization ages of 286 5 2 1 ma and 286 7 2 1 ma respectively the granitic and rhyolitic rocks have typical a type granite geochemical signatures i e high oxide ratios in wt k2o na2o k2o na2o cao k2o mgo and sio2 high trace element values zr nb ga ce y and ree and high zr ce y and 10 000 ga al ratios however spidergrams and ree patterns indicate major depletions in ba sr p ti and eu the presence of positive end t values of 7 0 to 11 2 and low 87sr 86sr i 0 70148 0 70416 indicates that these alkaline rocks were derived from a depleted mantle and not from old continental crust the geochemical characters indicate that the rocks of the complex have the same source and that fractionation was important in their generation a type granitic rocks are the most highly fractionated of alkaline basic rocks in summary the shaerhu complex is a product of mantle derived alkaline magma fractionation which is one of the main mechanisms of a type granite genesis the felsic rocks of the shaerhu complex have the geochemical signature of an a2 type granite and thus were not derived from a rift or mantle plume in the early permian oblique subduction in the southern altaids gave rise to strike slip extensional faults which controlled the emplacement of large volumes of mantle derived melts

oxygen and hydrogen isotope characteristics of hydrothermal alteration at the ann mason porphyry copper deposit yerington nevada late cenozoic normal faulting has tilted a 3 by 5 km block containing the mid jurassic ann mason porphyry copper deposit 90o w and exposed the hydrothermal alteration pattern in cross section from 1 to 6 km palcodepth oxygen and hydrogen isotopes have been used to deduce sources of hydrothermal fluids fresh samples of the host yerington batholith pluton have typical calc alkaline magmatic isotopic compositions 18 o whole rock 6 7 7 0 d biotite 85 to 88 the various types of hydrothermally altered rocks have similar d and 18 o values only slightly isotopically shifted from original magmatic values except along an axial zone within and above the orebody in this zone altered rocks are enriched in 18 o by 1 to 3 5 per mil and 18 o values increase with decreasing palcodepth the 18 o values of the whole rock and or feldspar and the d values of biotite chlorite and or actinolite in the various alteration zones are as follows propylitic alteration is widespread and is isotopically similar to fresh rock 18 o 6 2 to 7 2 per mil d 82 to 92 per mil potassic alteration characterized by 100 percent alteration of hornblende to biotite and cu mineralization occurs at 3 5 km palcodepth along the axis of the mineralizing granite porphyry dike swarm 18 o 6 5 to 8 4 per mil d 68 to 96 per mil sodic calcic alteration characterized by hydrothermal oligoclase actinolite sphene occurs laterally alongside and below the ore zone at 3 to 6 km palcodepth 18 o 5 7 to 8 4 per mil d 67 to 90 per mil late stage sodic albite chlorite alteration occurs at 1 to 4 km palcodepth in the vicinity of the axial zone 18 o 6 7 to 9 6 per mil d 79 to 85 per mil the youngest late stage sericitic alteration occurs at the shallowest levels primarily at 1 to 2 km palcodepth and displays a distinct 18 o and d enrichment 18 o 9 8 to 10 4 per mil d 61 per mil integration of stable isotope data geologic field relations and phase equilibria constraints indicates that the high salinity fluids responsible for potassic alteration and cu mineralization were of internal magmatic origin but that synchronous deep convecting saline sodic calcic fluids were largely derived from external nonmagmatic sources a third type of fluid also external but lower in temperature and much more dilute was prevalent at shallow levels and caused latestage sericitic alteration this was either an isotopically heavy coastal meteoric water or a seawater

magnetite geochemistry of the heijianshan fe cu au deposit in eastern tianshan metallogenic implications for submarine volcanic hosted fe cu deposits in nw china abstract the heijianshan fe cu au deposit is located in the aqishan yamansu belt in eastern tianshan nw china as a typical fe cu deposit in the region heijianshan is hosted in the upper carboniferous matoutan formation submarine volcanic volcaniclastic rocks alteration styles mineral assemblages and vein crosscutting relationships divide the hydrothermal alteration and mineralization processes into seven stages namely the chromite stage i epidote stage ii magnetite stage iii pyrite stage iv cu au stage v late veins stage vi and supergene stage vii alteration mineralization stages magnetite mineralization comprises the hematite stage iii a and main magnetite stage iii b mineralization sub stages the heijianshan magnetite ores consist of massive with mushketovite mom or sulfides mos disseminated do and magnetite clasts with chromite mwc or without chromite mnc ores magnetite in massive and disseminated ores is featured by 1 depletion in zr nb and ta 2 low ti f o 2 increased which may represent the major controls on the formation of the various magnetite ore types compositions of the ore fluids and host rocks formation of coexisting minerals and other physicochemical parameters such as t and f o 2 may have variably influenced the magnetite geochemistry in the different heijianshan ore types with fluid compositions probably playing the most important role discrimination diagrams for instance cr vs co ni cr vs ti v vs cr and ni vs cr may be useful for magnetite mineralization type differentiation in other submarine volcanic hosted fe fe cu deposits in the aqishan yamansu belt geochemical discrimination diagrams alteration and mineralization paragenesis indicate that the heijianshan fe cu au deposit is best classified as an iocg like deposit which offers a new insight for classifying and characterizing ore genetic types for similar fe and fe cu deposits in eastern tianshan