genesis of the fuxing porphyry cu deposit in eastern tianshan china evidence from fluid inclusions and c h o s pb isotope systematics abstract the fuxing porphyry cu deposit is a recently discovered deposit in eastern tianshan xinjiang northwestern china the cu mineralization is associated with the fuxing plagiogranite porphyry and monzogranite mainly presenting as various types of hydrothermal veins or veinlets in alerted wall rocks with potassic chlorite phyllic and propylitic alteration developed the ore forming process can be divided into four stages stage i barren quartz veins stage ii quartz chalcopyrite pyrite veins stage iii quartz polymetallic sulfide veins and stage iv quartz calcite veins four types of fluid inclusions fis can be distinguished in the fuxing deposit including hypersline h type vapor rich two phase v type liquid rich two phase l type and trace amounts of pure vapor inclusions p type but only the stage i quartz contains all types of fis the stages ii and iii quartz have two types of fis with exception of h and p types in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 357 518 c 255 393 c 234 322 c and 145 240 c with salinities of 1 9 11 6 wt nacl equiv 1 6 9 6 wt nacl equiv 1 4 7 7 wt nacl equiv and 0 9 3 7 wt nacl equiv respectively the ore forming fluids of the fuxing deposit are characterized by high temperature moderate salinity and relatively oxidized condition carbon hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials were derived from a deep seated magma source the cu mineralization in the fuxing deposit occurred at a depth of 1 km and the changes of oxygen fugacity decompression boiling and local mixing with meteoric water were most likely critical for the formation of the fuxing cu deposit

sims zircon u pb and molybdenite re os geochronology hf isotope and whole rock geochemistry of the wunugetushan porphyry cu mo deposit and granitoids in ne china and their geological significance abstract the geodynamic setting of magmatic rocks and geodynamic mechanism of cu mo fe sn pb zn ag polymetallic mineralization in northeastern ne china are attracting increasing attention this study explores these issues by providing sims zircon u pb dating whole rock geochemical hf isotopic data of magmatic rocks and molybdenite re os dating exposed in the wunugetushan porphyry cu mo deposit ne china this deposit is located in the western part of the great xing an range on the southeastern margin of the mongol okhotsk orogenic belt molybdenite re os and sims zircon u pb dating of the host monzogranitic porphyry and the wall rock of biotite granite in the wunugetushan porphyry cu mo deposit indicate that the ore formation host porphyry and wall rock emplacement occurred at 180 5 2 0 ma 180 4 1 4 ma and 203 5 1 6 ma respectively and the mineralization of the wunugetushan porphyry cu mo deposit occurred during the same period as that of the host monzogranitic porphyry geochemically the wunugetushan granitoids are characterized by strong lree hree fractionation and pronounced negative nb ta and ti anomalies with slightly negative eu anomalies eu eu 0 71 0 97 of the host monzogranitic porphyry and pronounced negative eu anomalies eu eu 0 29 0 32 of the wall rock of biotite granite in situ hf isotopic analyses of zircons from the host monzogranitic porphyry and the wall rock of biotite granite yielded ehf t values ranging from 0 5 to 8 2 and from 6 9 to 5 9 respectively the geochemical and isotopic data for the wunugetushan granitoids imply that the primary magmas of the host monzogranitic porphyry could have originated by partial melting of a thickened lower crust with input of mantle components while the primary magmas of the wall rock of biotite granite could have been derived by partial melting of a thickened lower crust that mixed with ancient crustal materials based on the regional geological history geochemistry of the wunugetushan granitoids and new isotopic age data we suggest that the formation of the wunugetushan porphyry cu mo deposit was possibly induced in the early jurassic during the period of the southeastward subduction of the mongol okhotsk oceanic plate beneath the erguna massif

ages and geodynamic settings of xilamulun mo cu metallogenic belt in the northern part of the north china craton abstract the xilamulun belt along the northern part of the north china craton is located in eastern segment of the central asian orogenic belt and has great economic potential for mo cu mineralization more than ten medium to large ore deposits have been discovered in this region in the recent years the major types of mineralization type include porphyry chehugou mo cu kulitou mo cu xiaodonggou mo and jiguanshan mo quartz vein nianzigou mo xinjing mo epithermal hongshanzi mo u and alteration assemblage liulingou mo the timing of mineralization was previously thought to be yanshanian 208 290 ma however indosinian 260 208 ma ages for intrusions and mineralization have been recognized in recent years based on geochronologic data and regional geological evidence it is suggested that the mineralization in the xilamulun belt was formed during multiple events the mineralization processes are related to a post collisional extension stage 258 210 ma with the generation of the porphyry molybdenum copper deposit a tectonic stress transformation from ns to ew 185 150 ma that gave rise to vein or porphyry molybdenum deposit and a lithospheric thinning stage 140 110 ma with porphyry molybdenum deposit

fluid inclusions and h o s pb isotope systematics of the baishan porphyry mo deposit in eastern tianshan china abstract the baishan porphyry mo deposit formed in the middle triassic in eastern tianshan xinjiang northwestern china mo mineralization is associated with the baishan monzogranite and granite porphyry stocks mainly presenting as various types of hydrothermal veinlets in alerted wall rocks with potassic phyllic propylitic and fluorite alteration the ore forming process can be divided into four stages stage i k feldspar quartz pyrite veinlets stage ii quartz molybdenite pyrite veinlets stage iii quartz polymetallic sulfide veinlets and stage iv barren quartz calcite veins four types of fluid inclusions fis can be distinguished in the baishan deposit namely liquid rich two phase l type vapor rich two phase v type solid bearing multi phase s type and mono phase vapor m type inclusions but only the stage i quartz contains all types of fis the stages ii and iii quartz have three types of fis with exception of m type in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 271 468 c 239 349 c 201 331 c and 134 201 c with salinities of 2 2 11 6 wt nacl equiv 1 1 10 2 wt nacl equiv 0 5 8 9 wt nacl equiv and 0 2 5 7 wt nacl equiv respectively the ore forming fluids of the baishan deposit are characterized by high temperature moderate salinity and relatively reduced condition belonging to a h 2 o nacl ch 4 co 2 system hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials came predominantly from a deep seated magma source from the lower continental crust the mo mineralization in the baishan deposit is estimated to have occurred at a depth of no less than 4 7 km and the decrease in temperature and remarkable transition of the redox condition from alkalinity to acidity of ore forming fluids were critical for the formation of the baishan mo deposit

geology geochronology fluid inclusion and h o isotope geochemistry of the luoboling porphyry cu mo deposit zijinshan orefield fujian province china abstract the luoboling cu mo deposit in the zijinshan orefield fujian province southeastern china is a large porphyry deposit hosted by the sifang granodiorite and the luoboling granodiorite porphyry the largest cu mo orebody is saddle shaped with various types of hydrothermal veinlets intensive hydrothermal alteration in the deposit is characterized by outward zoning from potassic overprinted by phyllic alteration to phyllic and alunite dickite alteration based on the mineral assemblages and crosscutting relationships of veins the ore forming process can be divided into three stages namely an early stage k feldspar quartz magnetite molybdenite veins associated with potassic alteration a middle stage quartz molybdenite chalcopyrite pyrite veins in phyllic zone and a late stage quartz gypsum veins in the phyllic and alunite dickite alteration zones six molybdenite separates yield a re os isochron age 104 6 1 0 ma which is identical to the age of emplacement of the sifang and luoboling granodiorite porphyries three types of fluid inclusions fis were observed at the luoboling deposit 1 nacl h 2 o aqueous 2 daughter mineral bearing and 3 co 2 h 2 o fluid inclusions fis of the early and middle stages are predominantly vapor rich aqueous and daughter mineral bearing inclusions together with minor co 2 rich and liquid rich aqueous inclusions whereas the late stage minerals only contain liquid rich aqueous inclusions homogenization temperatures and salinities of fis trapped in the early stage minerals range from 420 to 540 c and 0 4 to 62 9 wt nacl equiv respectively fis of the middle stage yield homogenization temperatures of 340 to 480 c and salinities of 0 5 to 56 0 wt nacl equiv co 2 content and the oxygen fugacity indicated by daughter minerals of fis trapped in middle stage minerals are lower than those in the early stage the liquid rich aqueous inclusions of the late stage homogenize at temperatures of 140 to 280 c yielding salinities of 0 4 to 8 4 wt nacl equiv the minimum estimated pressures of the three stages are 30 70 mpa 10 40 mpa and 1 10 mpa respectively corresponding to minimum ore forming depths of 1 2 8 km fluids trapped in early middle and late stages yield d values of 67 to 54 54 to 70 and 62 and 18 o values of 5 4 to 6 7 2 8 to 4 2 and 2 1 respectively fluid boiling which resulted in the formation of stockworks and the precipitation of sulfides occurred in the early and middle stages the fluids subsequently evolved into a low temperature low salinity system in the late stage along with an input of meteoric water the luoboling porphyry cu mo system was developed in a transition from continental arc to back arc extension region which was related to the westward subduction of the paleo pacific plate beneath the huanan orogen

re os and 40ar 39ar ages of the jiguanshan porphyry mo deposit xilamulun metallogenic belt ne china and constraints on mineralization events the large jiguanshan porphyry mo deposit with more than 100 mt of ore and grades ranging from 0 08 to 0 11 is located in the newly identified xilamulun metallogenic belt along the northern margin of the north china craton the mo mineralization is predominantly disseminated in the host granite porphyry but locally occurs as stockworks in lithic tuff and rhyolitic rocks 40ar 39ar dates of samples from groundmass material in the host granite porphyry post ore diabase and quartz porphyry dikes show plateau ages of 155 1 1 9 149 4 0 9 and 147 6 0 9 ma with inverse isochron ages of 156 0 1 8 149 3 1 3 and 148 3 1 2 ma respectively seven samples of disseminated molybdenite yielded a weighted average 187re 187os age of 155 3 0 9 ma whereas six veinlet type molybdenite samples yielded a weighted average 187re 187os age of 153 0 0 9 ma providing direct timing constraints for the mo mineralization at 153 155 ma the regional geological setting together with the emplacement of post ore diabase and quartz porphyry dikes in the jiguanshan deposit are indicative of an extensional regime in late jurassic which was probably linked to lithospheric extension in northeast china

large scale porphyry type mineralization in the central asian metallogenic domain a review abstract a series of porphyry type cu mo au deposits including some giant world class deposits such as kounrad aktogai kal makyr oyu tolgoi and chalukou occur in the central asian metallogenic domain camd the outline of the camd almost overlaps with that of the central asian orogenic belt caob which is located between the east europe siberia tarim and north china cratons the camd comprises sparsely exposed tectonic slices of precambrian high grade metamorphic basement rocks that are sandwiched between phanerozoic accretionary complexes and arc rocks according to geological metallogenic geochronological and tectonic setting characteristics the camd comprises three metallogenic provinces 1 the kazakhstan cu au mo 2 the mongolia cu au and 3 the northeast china mo cu metallogenic provinces early paleozoic 490 to 440 ma and late paleozoic 330 to 295 ma large scale porphyry type mineralization in the kazakhstan metallogenic province is intimately associated with the evolution of the central tianshan yili northern tianshan kokchetav chingiz paleozoic arc system which was terminated by the late permian closure of the western segment of the paleo asian ocean in contrast the 370 ma and 240 ma porphyry type mineralization of the mongolia metallogenic province is related to the tuva mongolia arc collage system that was formed during the evolution of the paleo asian ocean in the paleozoic and the mongol okhotsk ocean in the early mesozoic furthermore the northeast china metallogenic province was affected by three distinct geodynamic processes that were associated with the paleo asian mongol okhotsk and paleo pacific oceans during the paleozoic 250 ma the early mesozoic 200 ma and the late mesozoic 200 90 ma respectively except for the early paleozoic cu mineralization at duobaoshan 480 ma and bainaimiao 440 ma the porphyry type mineralization of this metallogenic province is predominantly characterized by widespread mesozoic mo mineralization in general porphyry type deposits of the camd have geological structural metallogenic alteration and fluid characteristics which are consistent either with those related to the oceanic subductional arc settings of the circum pacific metallogenic domain or with those of the continental collisional environment in the tethyan metallogenic domain the involvement of highly oxidized intermediate to felsic magmas is fundamental for the formation of porphyry deposits even though the prevalent mash and slab melting models can be employed to interpret the genesis of some porphyry cu deposits in the camd a here newly suggested model which is based on pre enriched mafic lower crust and the subduction of a relictic mid oceanic ridge is thought to explain the large scale copper mineralization in the balkhash west junggar metallogenic belt of the kazakhstan metallogenic province nevertheless most of the porphyritic suites associated with the mo deposits in the northeast china metallogenic province have relatively depleted mantle like neodymium and hafnium isotopic compositions suggesting that the ore forming granitic magma may have predominantly been derived from juvenile lower crust upwelling of asthenosphere may have triggered the melting of the lower crust during post collisional extension subsequent to the closure of the paleo asian ocean in the triassic the subduction of the paleo pacific ocean in the jurassic and the thinning of the lithosphere caused by rollback of the paleo pacific plate in the cretaceous ancient crustal components were only locally found to have been involved in the magma source of several medium large mo deposits

geology re os ages sulfur and lead isotopes of the diyanqinamu porphyry mo deposit inner mongolia ne china the diyanqinamu porphyry mo deposit in the southern greater khingan range of the central asian orogenic belt contains 800 million metric tons mt of ore with an average grade of 0 097 molybdenum the deposit is hosted in late jurassic volcanic rocks of tuff andesite and volcanic breccia multiple stage hydrothermal activities have resulted in propylitic phyllic and argillic alteration in this deposit five stages i v of hydrothermal activity are identified stage i is represented by a mineral assemblage of epidote chlorite and magnetite with some discontinuous barren veinlets of quartz k feldspar fluorite magnetite epidote chlorite stage ii is marked by occurrence of quartz fluorite molybdenite magnetite pyrite sericite siderite veinlets veins with phyllic halos stage iii consists of fluorite siderite quartz molybdenite pyrite ankerite calcite chalcopyrite veins that are commonly related to phyllic alteration and dissemination of fluorite in the altered rocks stage iv has an assemblage of fluorite quartz pyrite ankerite calcite molybdenite chalcopyrite sphalerite galena in coarse veins 10 20 mm wide stage v consists of narrow 5 mm wide veinlets of calcite fluorite pyrite quartz molybdenite mainly occurs in stages ii and iii re os dating results for molybdenite samples from these two stages yielded an isochron age of 156 2 4 2 ma 2 mswd 0 96 n 10 most molybdenite samples have high 34s values 8 4 relative to other sulfide minerals i e galena sphalerite pyrite and chalcopyrite of stages ii to v 34s 2 5 8 3 n 22 molybdenite also has low 207pb 204pb and 208pb 204pb ratios relative to other sulfide minerals although there are minor overlaps in a diagram of 206pb 204pb versus 207pb 204pb these pb isotope data display a positive trend transecting the growth curves of crustal lead which could be invoked by mixing of crustal and mantle sources with distinct pb isotopes in combination with the s isotope data and mineral paragenesis we suggest that magmas were the main source of molybdenum whereas other metals i e pb zn and cu were possibly sourced from the country rocks

ages and petrogenesis of the late mesozoic igneous rocks associated with the xiaokele porphyry cu mo deposit ne china and their geodynamic implications abstract the genesis of igneous rocks associated with the newly discovered xiaokele porphyry cu mo deposit located in the eastern erguna block ne china can give insights into the regional geodynamic evolution during the late mesozoic several ore bodies have been identified in a granodiorite porphyry stock which intruded the rhyolite and was subsequently intruded by diorite porphyry and granite porphyry the u pb ages of zircons from rhyolite mineralized granodiorite porphyry diorite porphyry and granite porphyry associated with the xiaokele deposit are 152 5 1 7 150 0 1 6 147 9 1 3 and 123 2 1 7 ma respectively the rhyolite and granite porphyry have high sio2 and low mgo cr co and ni contents their isotopic data show negative end t values of 4 76 to 0 87 initial 87sr 86sr ratios of 0 7066 to 0 7134 and positive zircon ehf t values of 0 33 5 56 indicating that they were derived from a basaltic lower continental crust the mineralized granodiorite porphyry is characterized by high sr y values and low y 3 7 8 0 contents showing adakite affinity the low k2o na2o 0 51 0 7 ratios high cao contents weakly negative end t 1 17 to 0 27 and low zircon ehf t 1 49 5 4 values from the adakitic samples indicate that they were derived from the partial melting of an altered oceanic slab together with assimilation of mantle peridotite and crustal materials the 148 ma diorite porphyry has high mg 51 58 weakly negative and positive end t 0 09 to 0 01 values and lower 87sr 86sr i 0 7055 0 7057 ratios suggesting an enriched mantle wedge source considering the late mesozoic regional tectonic evolution of the erguna block and adjacent area we propose that the formation of the xiaokele deposit is linked to the southward flat slab subduction of the mongol okhotsk oceanic plate during the later jurassic early cretaceous

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

triassic volcanism in eastern heilongjiang and jilin provinces ne china chronology geochemistry and tectonic implications abstract with the aim of constraining the early mesozoic tectonic evolution of the eastern section of the central asian orogenic belt caob we undertook zircon u pb dating and geochemical analyses major and trace elements sr nd isotopes of volcanic rocks of the luoquanzhan formation and daxinggou group in eastern heilongjiang and jilin provinces china the analyzed rocks consist mainly of dacite and rhyolite with sio2 contents of 68 52 76 65 wt three samples from the luoquanzhan formation and one from the daxinggou group were analyzed using laser ablation inductively coupled plasma mass spectrometry la icp ms u pb zircon techniques three zircons with well defined oscillatory zoning yielded weighted mean 206pb 238u ages of 217 1 214 2 and 208 1 ma and one zircon with oscillatory zoning yielded a weighted mean 206pb 238u age of 201 1 ma these ages are interpreted to represent the timing of eruption of the volcanic rocks the triassic volcanic rocks are characterized by high sio2 and low mgo concentrations enrichment in large ion lithophile elements liles and light rare earth elements lrees depletion in high field strength elements hfses and heavy rare earth elements hrees 87sr 86sr i 0 7040 0 7050 luoquanzhan formation and 0 7163 0 7381 daxinggou group and end t 1 89 3 94 luoquanzhan formation and 3 42 3 68 daxinggou group these geochemical features indicate an origin involving the partial melting of juvenile lower crust nd model ages tdm2 of 651 821 ma and that compositional variation among the volcanic rocks arose from mineral fractionation and minor assimilation these volcanic rocks formed within an extensional environment following collision of the ncc and jiamusi khanka massif during the late paleozoic early triassic

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

origin of the badaguan porphyry cumo deposit inner mongolia northeast china constraints from geology isotope geochemistry and geochronology abstract the badaguan porphyry cu mo deposit is located in the derbugan metallogenic belt of northeastern inner mongolia china the host granodioritic porphyry and the wall rock granitic porphyry were emplaced at 230 ma and 238 ma respectively the granodioritic porphyry has 87 sr 86 sr i values of 0 70535 0 70549 e nd t values of 0 41 1 17 e hf t values of 1 30 6 51 and two stage model ages t dm2 of 1131 848 ma in contrast the granitic porphyry is characterized by e hf t values from 0 75 to 7 28 that yield t dm2 model ages of 1355 816 ma the geochemical and sr nd hf isotopic data for the magmatic rocks associated with the badaguan porphyry cu mo deposit indicate that these intrusions were generated by the partial melting of juvenile lower crust the 18 o values of ore fluids from different mineralizing stages are between 6 0 and 1 5 and the fluid d water values vary from 119 3 to 140 0 indicating a mixed fluid of magmatic and meteoric water the s pb isotopes show that the metal was mostly derived from a deep seated magma that involved some crustal materials with a narrow 34 s range 2 4 to 3 5 we infer that the badaguan porphyry cu mo deposit formed during a period of southeast directed subduction of the mongol okhotsk oceanic plate beneath the erguna block

timing of the yuchiling giant porphyry mo system and implications for ore genesis the yuchiling mo deposit is a recently discovered giant porphyry system in the east qinling mo belt china its apparent causative intrusion i e the yuchiling granite porphyry is the youngest intrusion phase 4 of the heyu multiphase granite batholith which was emplaced between 143 and 135 ma new robust constraints on the formation of the yuchiling porphyry mo system are provided by combined zircon u pb biotite 40ar 39ar and molybdenite re os dating zircon grains from the mo mineralized granite porphyry yield weighted 206pb 238u age of 134 0 1 4 ma n 19 2 error mswd 0 30 magmatic biotite from the same sample yield a 40ar 39ar plateau age of 135 1 1 4 ma 2 error and an inverse isochron age of 135 6 2 0 ma n 7 2 error mswd 10 8 which are effectively coincident with the zircon u pb age within analytical error three pulses of mineralization can be deduced from the molybdenite re os ages namely 141 137 and 134 ma which agree well with the zircon u pb ages of granitic phases 1 2 and the yuchiling porphyry phase 4 respectively these well constrained temporal correlations indicate that mo mineralization was caused by pulses of granitic magmatism and that the ore forming magmatic hydrothermal activity responsible for the yuchiling porphyry mo system lasted about 8 ma the yuchiling mo deposit represents a unique style of porphyry mo system formed in a post collision setting and associated with f rich high k calc alkaline intrusions which differ from convergent margin associated porphyry mo deposits

depth limited design wave heights in very flat regions abstract engineers working on the flat tops of offshore coral reefs or offshore banks require design criteria for depth limited wave heights over horizontal beds particularly in regions leeward of the bank or reef edge surf zone this paper presents convincing evidence of the fact that in engineering practice both in the laboratory and in the field the value of 0 55 is the largest wave height to water depth ratio realizable for stable shallow water oscillatory waves propagating in water of constant depth horizontal bed this value is much lower than that often used in engineering practice namely a value of about 0 8 which is historically based on the theoretical considerations and laboratory experiments associated with solitary waves this result based on a review of laboratory data and the original results of a major field experiment undertaken on the great barrier reef of australia leads to a significant reduction in design wave forces design crest levels and wave induced scour velocities at the bed

geological and geochemical characteristics of the sawaya erdun gold deposit southwestern chinese tianshan the sawaya erdun gold deposit in the western segment of the south tianshan xinjiang china is a large low grade orogenic gold deposit an abundance of index fossils in the ore hosting strata including brachiopoda corals and schwagerina show that the fossil age of the country rocks ranges from late carboniferous to early permian whole rock rb sr and sm nd isochron ages ranging from 292 43 0 38 to 304 7 11 6 ma are concordant with a late carboniferous age gold mineralization is strictly controlled by a fault zone ore minerals are dominated by sulfides with gold inhomogeneously distributed within them gangue minerals are quartz siderite or calcite data suggest that the ore forming fluid was derived predominantly from an active meteoric groundwater system ore forming temperatures are estimated to have been within the range 110 to 220 c new 40 ar 39 ar isotope age determinations of auriferous quartz are in excellent agreement with rb sr ages obtained from fluid inclusions in quartz they suggest gold mineralization at 206 to 213 ma late indosinian such an age is consistent with the age of formation given for other gold deposits in the region such as bulong and dashankou combined with k ar geochronological data and observed geological features it is concluded that the indosinian metallogentic epoch represents a previously unrecognized major period of gold metallogeny in the southwestern chinese tianshan in some ways the sawaya erdun gold deposit can be compared with the muruntau gold deposit in uzbekistan with respect to geological setting host lithology mineralization style mineral assemblages geochemical association and metallogenic processes involved despite this the sawaya erdun gold deposit possesses a number of characteristics typical of only low temperature metallogenesis 2007 elsevier b v all rights reserved

isotopic geochemistry of the sawayaerdun orogenic type gold deposit tianshan northwest china implications for ore genesis and mineral exploration the sawayaerdun gold deposit is hosted by carbonaceous metasediments and is considered to be the largest muruntau type gold deposit in the chinese tianshan metallogenic belt gold mineralization at sawayaerdun occurs in quartz veins associated with three major hydrothermal events an early barren quartz vein stage middle stage mineralized quartz veins with pyrite and late carbonate quartz veins the isotopic compositions of quartz and sulfides from the sawayaerdun gold deposit show some variation but are generally comparable to those of other orogenic type gold deposits fluids trapped in early stage quartz have a 18o range of 13 6 to 15 4 d of 48 to 75 13c of 0 5 to 4 2 and 30si of 0 2 to 0 in contrast isotopic compositions of fluids trapped in middle stage quartz have 18o values of 6 7 to 14 7 d of 56 to 110 13c of 0 4 to 10 1 and 30si of 0 3 to 0 diagenetic and hydrothermal pyrite have similar sulfur 1 8 to 0 9 and pb isotopic values that are associated with host rock compositions the early stage 18o and 13c rich fluids are probably derived from metamorphic decarbonation of the sedimentary host rock at depth leading to the precipitation of early barren quartz veins in the middle stage a decrease in the regional pressure and temperature regime could have resulted in the incorporation of external fluids into the ore forming system these external fluids with isotopic signatures similar to that of the host rock and generally rich in 34s and radiogenic pb mixed with original ore forming fluids to generate extensive metal precipitation late stage fluids trapped by calcite veins show isotopic compositions similar to meteoric water indicating the cessation of hydrothermal fluid circulation at sawayaerdun occurred at this time the metallogenetic model illustrated by stable and pb isotopes is also consistent with fluid inclusion studies in sawayaerdun the development of mineralization at sawayaerdun is strongly linked to fluid mixing as witnessed by the isotopic signatures of fluids from identified ore bearing zones the isotopic compositions of other anomalous zones at sawayaerdun are similar to those of the mineralized zones suggesting a high potential for further exploration 2012 elsevier b v

the western central asian orogenic belt a window to accretionary orogenesis and continental growth abstract the architecture of accretionary orogens is a key to understand continental growth here we present an overview of the orogenic components and their amalgamation in the western central asian orogenic belt caob the caob records the convergence and interactions among various types of orogenic components including the japan type mariana type and alaska aleutian type arc systems as well as the active marginal sequences of the siberia craton which incorporated wide accretionary complexes and accreted arcs and terranes during construction of the caob the kazakhstan arc chain was characterized by multiple subduction whereas the northern fringe of the tarim craton remained mostly as a passive margin the multiple convergence and accretions among these various orogenic components generated huge orogenic collages in the late paleozoic and even in the early triassic involving parallel amalgamation circum microcontinent amalgamation and oroclinal bending the preservation of trapped basins played a significant role in orogenesis with some parts of the oceanic plate being subducted and others behaving as rigid units the orogenesis in the caob was long lived lasting for more than 800 m y involving multiple subduction and long continuous accretion and featuring the complexity of accretionary orogenesis and continent growth

fluid inclusions and h o s pb isotope systematics of the chalukou giant porphyry mo deposit heilongjiang province china abstract the chalukou giant porphyry mo deposit located in the northern great xing an range is the largest mo deposit in the xing an mongolia orogenic belt this deposit s ore bodies are mainly hosted in an intermediate felsic complex and jurassic volcanic sedimentary rocks of which late jurassic granite porphyry quartz porphyry and fine grained granite are closely associated with the mo mineralization three types of fluid inclusions fis are present in the quartz associated with oxide and sulphide minerals i e liquid rich two phase gas rich two phase and daughter mineral bearing multiphase fis the fis in the quartz phenocrysts of the granite porphyry contain liquid rich two phase gas rich two phase and daughter mineral bearing multiphase fis the homogenization temperatures vary from 230 c to 440 c and 470 c to 510 c and their salinities vary from 0 7 to 53 7 nacl eq and 6 2 to 61 3 nacl eq respectively the fis of k feldspar quartz magnetite veins of the early stage are composed of liquid rich two phase gas rich two phase and daughter mineral bearing multiphase fis with homogenization temperatures and salinities of 320 c to 440 c and 4 2 to 52 3 nacl eq respectively the fis of quartz molybdenite veins and breccia of the middle stage are composed of liquid rich two phase gas rich two phase and daughter mineral bearing multiphase fis with homogenization temperatures and salinities of 260 c to 410 c and 0 4 to 52 3 nacl eq respectively fis of quartz fluorite galena sphalerite veins of the late stage are liquid rich two phase fis with homogenization temperatures and salinities of 170 c to 320 c and 0 5 to 11 1 nacl eq respectively the ore forming fluids of the chalukou deposit are characterised by high temperature high salinity and high oxygen fugacity belonging to an f rich h 2 o nacl co 2 system the 18 o w values vary from 4 5 to 3 2 and the d w values vary from 138 to 122 indicating that the ore forming fluids were a mixture of magmatic and meteoric water the 34 s values range from 1 9 to 3 6 with an average of 1 6 the 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb values of the metallic minerals are in the ranges of 18 269 18 501 15 524 15 567 and 38 079 38 264 respectively both the s and pb isotopic systems indicate that the ore metals and fluids came primarily from a deep seated magma source from the juvenile lower crust the mo mineralization in the chalukou deposit occurred at a depth of 0 5 to 1 3 km and multiple stages of phase separation or immiscibility of ore forming fluid was critical for the formation of the chalukou deposit

genesis of the wurinitu w mo deposit inner mongolia northeast china constraints from geology fluid inclusions and isotope systematics abstract the wurinitu w mo deposit is located in the erlian east ujimqin metallogenic belt in the great xing an range ne china tungsten and molybdenum mineralization generally occurs as veins in quartz hosted by the middle to lower ordovician wall rocks or as disseminations in the early cretaceous monzogranite intrusions fluid inclusion studies and multiple isotope analyses provide systematic evidence to determine the evolution of the hydrothermal fluids the source of metals and fluids as well as mineral precipitation mechanisms which are significant for the magmatic hydrothermal system but are poorly understood three types of fluid inclusion assemblages fias including l liquid rich two phase fias v vapor rich two phase fias and l v liquid vapor two phase fias have been identified in quartz veins from the w mineralization i mo mineralization ii and quartz carbonate iii stages at wurinitu the ore forming fluids evolved from a high to moderate temperature and moderate to low salinity h2o nacl co2 system in the w and mo mineralization stages to a low temperature and low salinity h2o nacl system in the quartz carbonate stage they were trapped at temperatures of 365 c 266 c and 198 c the results of hydrogen and oxygen isotope analyses 18oh2o 4 0 to 7 7 dh2o 116 to 92 indicate that the stage i fluids dominantly originated from magmatic water and the stages ii and iii show addition of meteoric water sulfur 34svcdt 1 9 4 0 and lead isotope values 206pb 204pb 18 099 18 728 207pb 204pb 15 527 15 616 and 208pb 204pb 38 019 38 465 suggest that the ore metals in the hydrothermal fluids were derived from the granitic magma all these observations reveal that 1 the wurinitu w mo deposit is a magmatic hydrothermal ore system 2 w and mo mineralization occurred under lithostatic pressure of 203 294 bars and hydrostatic pressure of 102 bars respectively and 3 fluid boiling and mixing with meteoric water might be the key factors controlling the large scale ore deposition at wurinitu

genesis of the zhengguang gold deposit in the duobaoshan ore field heilongjiang province ne china constraints from geology geochronology and s pb isotopic compositions abstract the zhengguang gold deposit in the duobaoshan ore field hosted in volcanic rocks of the middle ordovician duobaoshan formation is one of the largest gold deposits in the northeastern great xing an range of the central asian orogenic belt caob the deposit comprises the no i ii and iii ore zones with a total resource exceeding 35 tonnes of au 100 000 tonnes of zn and 100 tonnes of ag a genetic relationship between gold mineralization and concealed tonalite porphyry is inferred based on the characteristics of cryptoexplosive breccia and hydrothermal alteration indicative of porphyry type and epithermal mineralization zircon la icpms u pb dating reveals that the tonalite porphyry was emplaced at 462 1 1 8 ma middle ordovician the 34 s v cdt values of sulfide minerals range from 3 0 to 1 7 with an average of 2 33 indicating that sulfur was mainly derived from a magmatic source the pb isotopic compositions 206 pb 204 pb ranging from 17 572 to 17 629 207 pb 204 pb from 15 424 to 15 486 and 208 pb 204 pb from 37 206 to 37 418 suggest a major mantle component for pb and by inference for other ore metals therefore we suggest that the ore forming elements in the zhengguang gold deposit may be related to the mantle sourced tonalite porphyry on the basis of the geological characteristics and geochemical signatures documented in this study we conclude that the zhengguang gold deposit was formed in a porphyry to epithermal transitional environment associated with the concealed tonalite porphyry as part of the duobaoshan porphyry epithermal ore system that is related to the subduction of the paleo asian ocean during the ordovician

the genesis of the ores and granitic rocks at the hongshi au deposit in eastern tianshan china constraints from zircon u pb geochronology geochemistry and isotope systematics abstract the hongshi gold deposit is located in the southwestern margin of the kanggur huangshan ductile shear zone in eastern tianshan northwest china the gold ore bodies are predominantly hosted in the volcanogenic metasedimentary rocks of the lower carboniferous gandun formation and the carboniferous syenogranite and alkali feldspar granite the syenogranite and the alkali feldspar granite yield shrimp zircon u pb ages of 337 6 4 5 ma 2 mswd 1 3 and 334 0 3 7 ma 2 mswd 1 1 respectively indicating that the hongshi gold deposit is younger than 334 ma the granitoids belong to shoshonitic series and are relatively enriched in large ion lithophile elements rb k ba and pb and depleted in high field strength elements nb ta p and ti moreover these granitoids have high sio 2 al 2 o 3 and k 2 o contents low na 2 o mgo and tio 2 contents low nb ta ratios and slightly positive eu anomalies the e hf t values of the zircons from a syenogranite sample vary from 1 5 to 8 8 with an average of 5 6 the e hf t values of the zircons from an alkali feldspar granite sample vary from 5 0 and 10 1 with an average of 7 9 the 34 s values of 10 sulfide samples ranged from 11 5 to 4 2 with peaks in the range of 1 to 4 the above mentioned data suggest that the hongshi granitoids were derived from the melting of juvenile lower crust mixed with mantle components formed by the southward subduction of the paleo tianshan ocean plate beneath the aqishan yamansu island arc during the early carboniferous the hongshi gold deposit was formed by post collisional tectonism during the permian the granitoids most likely acted as impermeable barriers that prevented the leakage and runoff of ore bearing fluids thus the granitoids probably played an important role in controlling gold mineralization

magma mixing origin for the aolunhua porphyry related to mo cu mineralization eastern central asian orogenic belt abstract many cu mo au deposits are considered to be related to adakitic porphyries formed in non arc settings e g in collisional orogenic zones and intra plate environments but their genesis is still under discussion the aolunhua porphyry complex and its related mo cu deposit from the eastern central asian orogenic belt caob provide important insights into this issue the porphyries are characterized by high sr 496 705 ppm and sr y and la yb ratios similar to those of typical adakitic rocks and low i sr ratios 0 7049 0 7052 and positive e nd t 0 5 to 1 4 and e hf t 3 5 to 9 8 values these features along with the occurrence of mafic microgranular enclaves mmes compositional and textural disequilibrium of plagioclase phenocrysts and relatively high mg values 45 52 indicate that they were derived from mixing of felsic magma from partial melting of a juvenile arc type lower crust and mafic magma from a lithospheric mantle previously metasomatized by subduction zone fluids melts high sr y and la yb ratios are indicative of contribution from enriched mantle derived materials with high liles e g sr la which were strengthened by subsequent fractionation of ferromagnesian phases such as pyroxene and hornblende mmes hosted by the ore bearing porphyry have zircon u pb ages of ca 132 ma similar to those of the host rocks the enclaves have elevated mg 56 63 liles e g sr 660 891 ppm lree la n 68 150 la sm n 3 0 4 0 la yb n 12 0 19 6 and ratios of radiogenic isotopes of nd and hf e nd 0 7 to 1 6 e hf 3 3 to 10 9 suggesting that their parental magmas were derived from the metasomatized mantle source the mo cu mineralization was probably related to the high water content high oxygen and sulfur fugacity of hybrid magma formation of the adakitic porphyries and related mo cu deposits of the eastern caob could be related to the early cretaceous lithospheric extension caused by the subduction of the paleo pacific plate and its induced reactivation of juvenile arc type lower crust

ore genesis and hydrothermal evolution of the wulandele mo deposit inner mongolia northeast china evidence from geology fluid inclusions and h o s pb isotopes abstract the newly identified wulandele mo deposit is located in the western part of the great xing an range northeast china molybdenum mineralization generally occurs as veins or disseminations hosted in permian to cretaceous granitic intrusions associated with potassic alteration silicification greisenization and propylitic alteration the ore forming process can be divided into four stages quartz k feldspar biotite pyrite stage i quartz molybdenite k feldspar pyrite stage ii quartz chalcopyrite bornite stage iii and quartz carbonate stage iv combined fluid inclusion microthermometry and stable and pb isotopic compositions are used to constrain the hydrothermal processes and ore genesis of the wulandele mo deposit fluid inclusion data show four types of fluid inclusion assemblages fias i e l0 liquid rich two phase fias v0 vapour rich two phase fias c co2 rich fias and rare l1 liquid rich three phase fias with one transparent mineral but only the former three types of fias were analysed aqueous and carbonic fluid inclusions occur in quartz veins of stages i and ii and only aqueous inclusions are observed in stages iii and iv hydrogen and oxygen isotopic compositions of quartz indicate a primarily magmatic origin and the proportion of meteoric water increased during the ore forming process sulfur 34svcdt 1 90 4 19 and lead isotopes suggest that the ore forming materials came predominantly from magmatic fluids the wulandele mo deposit was formed by an initially high temperature high oxygen fugacity and co2 rich fluid system at an estimated depth of 0 4 to 3 3 km decreases in temperature and fo2 as well as the input of meteoric water were critical factors for sulfide precipitation combining the integrated analysis of deposit geology the fluid evolutionary process and the ore forming environment we suggest that the wulandele deposit should be classified as a porphyry mo deposit that was formed in a continental collision orogen during post collisional extension associated with the consumption of the mongol okhotsk ocean in ne china

zircon u pb and molybdenite re os dating of the chalukou porphyry mo deposit in the northern great xing an range china and its geological significance abstract the newly discovered chalukou giant porphyry mo deposit located in the northern great xing an range is the biggest mo deposit in northeast china the chalukou mo deposit occurs in an intermediate acid complex and jurassic volcano sedimentary rocks of which granite porphyry quartz porphyry and fine grained granite are closely associated with mo mineralization however the ages of the igneous rocks and mo mineralization are poorly constrained in this paper we report precise in situ la icp ms zircon u pb dates for the monzogranite granite porphyry quartz porphyry fine grained granite rhyolite porphyry diorite porphyry and andesite porphyry in the chalukou deposit corresponding with ages of 162 2 ma 149 5 ma 148 2 ma 148 1 ma 137 3 ma 133 2 ma and 132 2 ma respectively analyses of six molybdenite samples yielded a re os isochron age of 148 1 ma these data indicate that the sequence of the magmatic activity in the chalukou deposit ranges from jurassic volcano sedimentary rocks and monzogranite through late jurassic granite porphyry quartz porphyry and fine grained granite to early cretaceous rhyolite porphyry diorite porphyry and andesite porphyry the chalukou porphyry mo deposit was formed in the late jurassic and occurred in a transitional tectonic setting from compression to extension caused by subduction of the paleo pacific oceanic plate

genesis of the hardat tolgoi ag pb zn deposit inner mongolia northeast china constraints from geology fluid inclusions and c o s pb isotope systematics abstract the hardat tolgoi ag pb zn deposit 4 3 mt at 3 15 pb zn and 26 4 g t ag is located in the erenhot east ujimqin polymetallic metallogenic belt on the western part of the great xing an range inner mongolia northeast china the ag pb zn mineralization mainly occurs as vein type ores hosted in argillaceous siltstone feldspar quartz sandstone with silty slate interlayers of the aobaotinghundi formation of lower devonian the hydrothermal ore forming process can be divided into three stages i e quartz pyrite arsenopyrite stage i quartz polymetallic sulfides stage ii and quartz calcite fluorite stage iii four types of fluid inclusions have been identified in the quartz bearing veins of each stage i e liquid rich two phase l type single liquid phase pw type vapor rich two phase v type and pure vapor phase pv type inclusions the fluid inclusions of stage i to iii yield homogenization temperatures of 285 407 c 202 317 c and 144 239 c with salinities of 1 2 9 2 wt nacl equiv 0 9 5 0 wt nacl equiv and 0 2 2 6 wt nacl equiv respectively the ore forming fluids at hardat tolgoi are characterized by moderate temperatures low salinities and low densities and dominated by the h2o nacl system carbon and oxygen isotope compositions of calcite demonstrate that the ore forming fluids come from a primary magmatic hydrothermal system with subsequent involvement of meteoric water at a later stage sulfur isotope analyses of sulfides yield 34sv cdt values of 1 8 to 8 7 with calculated 34sh2s values of 1 4 to 9 4 the 206pb 204pb 207pb 204pb and 208pb 204pb ratios of sulfides range from 18 141 to 18 468 15 521 to 15 617 and 38 040 to 38 377 respectively similar to those of granites from the hardat tolgoi deposit both sulfur and lead isotope data indicate that the ore forming metals were most likely derived from the magmatic reservoirs and sedimentary country rocks the available fluid inclusion results and isotope studies indicate that the pahse separation temperature decrease and fluid mixing resulted in large scale ag pb zn ore formation at hardat tolgoi

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

the crustal accretion history and tectonic evolution of the ne china segment of the central asian orogenic belt abstract the basement rocks in parts of ne china constitute a khondalitic sequence of sillimanite and garnet bearing gneisses hornblende plagioclase gneiss and various felsic paragneisses zircon u pb dating of garnet sillimanite gneiss samples from the erguna xing an jiamusi and khanka blocks indicates that high grade metamorphism occurred at 500 ma evidence from detrital zircons in paleozoic sediments from the songliao block also indicates the former presence of a 500 ma component this uniformity of u pb ages across all crustal blocks in ne china establishes a 1300 km long late pan african khondalite belt which we have named the ne china khondalite belt this indicates the blocks of ne china were amalgamated prior to 500 ma contrary to current belief one scenario is that this amalgamated terrane had a tectonic affinity to the siberia craton once forming part of the late pan african 500 ma sayang baikal orogenic belt extensively developed around the southern margin of the siberia craton this belt was the result of collision between currently unidentified terranes with the southeastern angara anabar province at about 500 ma where the rocks were deformed and metamorphosed to granulite facies it appears likely that at sometime after 450 ma the combined ne china blocks rifted away from siberia and moved southward to form what is now ne china the combined block collided with the north china craton along the solonker xar moron changchun suture zone at 230 ma rather than in the end permian as previously thought local rifting at the eastern extremity of the developing central asian orogenic belt caob resulted in the splitting away of the jiamusi khanka bureya blocks however this was only transient and sometime between 210 and 180 ma these were re united with the caob by the onset of pacific plate subduction which has dominated the tectonic evolution of the region since that time

cretaceous cenozoic tectonic history of the jiaojia fault and gold mineralization in the jiaodong peninsula china constraints from zircon u pb illite k ar and apatite fission track thermochronometry the jiaojia fault jjf in the jiaodong area of eastern china is an important nne trending structure that is subsidiary to the regional tancheng lujiang tan lu fault zone and hosts 1200 t of gold reserves contained in disseminated and stockwork ore dominantly in the footwall of the fault we present new zircon u pb apatite fission track and illite k ar data along the jjf and have delineated its tectonic history focusing on its formation and reactivation zircon u pb dating shows that the shangzhuang granite is a composite body with ages between 132 1 and 127 1 ma illite k ar ages for the fault s gouge range from 83 2 to 68 2 ma and the measured apatite fission track ages for ores are between 55 and 21 ma previous zircon u pb geochronology and structural studies suggest that the jjf was originally activated in the jurassic during 160 150 ma as a sinistral fault the jjf was a normal fault in the early cretaceous due to nw se orientated tension and ne sw compression which lasted from 135 to 120 ma this was followed by sinistral strike slip faulting due to nw se compression and ne sw tension during 120 110 ma and it changed to normal displacement at ca 110 ma our apatite fission track data analysis and thermal modeling of representative samples suggest that there was a subsequent dextral reactivation of the fault at ca 55 ma previous age data of ca 130 110 ma for gold mineralization along the jjf coincides with the early cretaceous magmatism and is coeval with the transition from normal faulting to sinistral strike slip faulting of the jjf in early cretaceous which is interpreted to be due to changing direction of the subducting pacific plate

a geochemical study of the sweet home mine colorado mineral belt usa hydrothermal fluid evolution above a hypothesized granite cupola deposition of quartz molybdenite pyrite topaz muscovite fluorite and subsequent hubnerite and sulfide fluorite rhodochrosite mineralization at the sweet home mine occurred coeval with the final stage of magmatic activity and ore formation at the nearby world class climax molybdenum deposit about 26 to 25 m y ago the mineralization occurred at depths of about 3 000 m and is related to at least two major fluid systems 1 one dominated by magmatic fluids and 2 another dominated by meteoric water the sulfur isotopic composition of pyrite strontium isotopes and rey distribution in fluorite suggest that the early stage quartz molybdenite pyrite topaz muscovite fluorite mineral assemblage was deposited from magmatic fluids under a fluctuating pressure regime at temperatures of about 400 c as indicated by co2 bearing moderately saline 7 5 12 5 wt nacl equiv fluid inclusions la icpms analyses of fluid inclusions in quartz demonstrate that fluids from the sweet home mine are enriched in incompatible elements but have considerably lower metal contents than those reported from porphyry cu au mo or climax type deposits the ore forming fluid exsolved from a highly differentiated magma possibly related to the deep seated alma batholith or distal porphyry stock s sulfide mineralization marking the periphery of climax type porphyry systems with fluorite and rhodochrosite as gangue minerals was deposited under a hydrostatic pressure regime from low salinity co2 bearing fluids with low metal content at temperatures below 400 c the sulfide mineralization is characterized by mostly negative 34s values for sphalerite galena chalcopyrite and tetrahedrite highly variable 18o values for rhodochrosite and low ree contents in fluorite the pb isotopic composition of galena as well as the highly variable 87sr 86sr ratios of fluorite rhodochrosite and apatite indicates that at least part of the pb and sr originated from a much more radiogenic source than climax type granites it is suggested that the sulfide mineralization at the sweet home mine formed from magmatic fluids that mixed with variable amounts of externally derived fluids the migration of the latter fluids that were major components during late stage mineralization at the sweet home mine was probably driven by a buried magmatic intrusion

modelling ore forming processes through a cosine similarity measure improved targeting of porphyry copper deposits in the manzhouli belt china abstract recognizing distribution patterns of ore related pathfinder elements requires an understanding of the corresponding ore forming systems and may lead to the definition of more reliable exploration targets given that complex ore forming processes in complex geological terrains can result in either enrichment or depletion of ore elements simultaneous consideration of both processes in geochemical anomaly modelling would be advantageous for defining exploration targets here we adapted the cosine similarity measure method for pattern recognition of ore related geochemical anomalism to facilitate simultaneous modelling of element enrichment and depletion we tested the performance of this new method on porphyry copper exploration data from the manzhouli belt china and demonstrated that our method is highly efficient with respect to recognizing ore related geochemical signatures and thus useful for vectoring towards porphyry copper deposits and defining more reliable geochemical exploration targets

paleozoic multiple accretionary and collisional tectonics of the chinese tianshan orogenic collage abstract subduction related accretion in the junggar balkash and south tianshan oceans paleo asian ocean mainly in the paleozoic gave rise to the present 2400 km long tianshan orogenic collage that extends from the aral sea eastwards through uzbekistan tajikistan kyrgyzstan to xinjiang in china this paper provides an up to date along strike synthesis of this orogenic collage and a new tectonic model to explain its accretionary evolution the northern part of the orogenic collage developed by consumption of the junggar balkash ocean together with paleozoic island arcs northern ili issyk kul and chatkal located in the west which may have amalgamated into a composite arc in the paleozoic in the west and by addition of another two roughly parallel arcs dananhu and central tianshan in the east the western composite arc and the eastern dananhu and central tianshan arcs formed a late paleozoic archipelago with multiple subduction zones the southern part of the orogenic collage developed by the consumption of the south tianshan ocean which gave rise to a continuous accretionary complex kokshaal kumishi which separated the central tianshan in the east and other paleozoic arcs in the west from cratons tarim and karakum to the south cross border correlations of this accretionary complex indicate a general southward and oceanward accretion by northward subduction in the early paleozoic to permian as recorded by successive southward juxtaposition of ophiolites slices of ophiolitic melanges cherts island arcs olistostromes blueschists and turbidites which are mainly paleozoic in age with the youngest main phase being late carboniferous permian the initial docking of the southerly tarim and karakum cratons to this complicated late paleozoic archipelago and accretionary complexes occurred in the late carboniferous early permian in the eastern part of the tianshan and in the late permian in the western part which might have terminated collisional deformation on this suture zone the final stages of closure of the junggar balkash ocean resembled the small ocean basin scenario of the mediterranean sea in the cenozoic in summary the history of the altaids is characterized by complicated multiple accretionary and collisional tectonics

shrimp zircon u pb geochronology geochemistry and h o si s pb isotope systematics of the kanggur gold deposit in eastern tianshan nw china implication for ore genesis abstract the kanggur gold deposit is located in the southern margin of the central asia orogenic belt and in the western segment of the kanggur huangshan ductile shear belt in eastern tianshan northwestern china the orebodies of this deposit are hosted in the lower carboniferous volcanic rocks of the aqishan formation and mainly consist of andesite dacite and pyroclastic rocks the shrimp zircon u pb age data of the andesite indicate that the volcanism in the kanggur area might have occurred at ca 339 ma in the early carboniferous and that the mineralization age of the kanggur gold deposit was later than the age of volcanic rocks in the area geochemically the andesite rocks of the aqishan formation belong to low tholeiite and calc alkaline series and display relative depletions in high field strength elements hfses i e nb ta and ti the 18 o w and d w values vary from 9 1 to 3 8 and 66 0 to 33 9 respectively indicating that the ore forming fluids were mixtures of metamorphic and meteoric waters the 30 si values of 13 quartz samples range from 0 3 to 0 1 with an average of 0 15 and the 34 s values of 18 sulphide samples range from 0 9 to 2 2 with an average of 0 54 the 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb values of 10 sulphide samples range from 18 166 to 18 880 15 553 to 15 635 and 38 050 to 38 813 respectively showing similarities to orogenic pb these values are consistent with those of the andesite from the kanggur area suggesting a common lead source all of the silicon sulphur and lead isotopic systems indicate that the ore forming fluids and materials were mainly derived from the aqishan formation and that the host volcanic rocks of the aqishan formation probably played a significant role in the kanggur gold mineralization integrating the data obtained from studies on geology geochronology petro geochemistry and h o si s pb isotope systematics we suggest that the kanggur gold deposit is an orogenic type deposit formed in eastern tianshan orogenic belt during the permian post collisional tectonism

tethys tectonic evolution and its bearing on the distribution of important mineral deposits in the sanjiang region sw china abstract the sanjiang region in se tibet plateau and nw yunnan is known to have formed by amalgamation of gondwana derived continental blocks and arc terranes as a result of oceanic subduction followed by continental collision from paleozoic to mesozoic in this paper we provide a synthesis of tectonic evolution magmatism and metallogeny in the region based on data from literatures early paleozoic ophiolites 473 439 ma in the changning menglian belt indicate the existence of a proto tethys ocean in this region two episodes of subduction related magmatism in the early paleozoic one occurred in the baoshan and tengchong blocks at 502 455 ma and the other occurred in the simao block at 421 401 ma are regarded as evidence for two different events of subduction of the proto tethys ocean at different locations the proto tethys was succeeded in early devonian by the paleo tethys which comprised the main ocean and three branches ailaoshan jinshajiang and garze litang the changning menglian main ocean existed from middle devonian to middle triassic the remnants of the oceanic crust are preserved in a few places in the longmu tso shuanghu suture as well as in the changning menglian ophiolite belt the eastward subduction of the main oceanic plate from early permian to early triassic formed a prominent arc terrane stretching 1500 km from yunnan to eastern tibet from the waning stage of subduction to post subduction numerous s type granite plutons with ages varying between 230 and 219 ma such as the lincang batholith in yunnan were emplaced at or close to the suture this event produced several hydrothermal w sn deposits in the region the tectonic evolution and associated magmatism of the jinshajiang and ailaoshan branch oceans are generally comparable to those of the main ocean however the branch oceans were subducted westward instead the garze litang branch ocean also underwent westward subduction from middle devonian to late triassic arc related high sr y porphyry intrusions and associated porphyry skarn cu mo au deposits are common in the jinshajiang ailaoshan region especially in the yidun arc which formed prior to jurassic the vms deposits in the sanjiang region formed in diverse tectonic settings including middle silurian back arc basins carboniferous oceanic islands paleozoic subduction zones and triassic post subduction rifting environments the mesozoic and early cenozoic evolution of the baoshan and tengchong blocks was largely influenced by eastward oceanic subduction of the meso and neo tethys from late permian to middle cretaceous and from late cretaceous to 50 ma respectively abundant early cretaceous granitoids and associated skarn type pb zn and sn fe deposits in the baoshan and tengchong blocks were produced in the background of the shan boundary oceanic slab subduction to the west and the break off of the nujiang bitu oceanic slab to the north the subduction of the neo tethys oceanic plate beneath the tengchong block from late cretaceous to paleogene formed abundant s type granitoids and many skarn type and greisen type sn w deposits granitoids formed at 105 to 81 ma and contemporaneous hydrothermal w mo ag and au deposits which temporally coincided with the subduction of the neo tethys are common in the yidun arc terrane

a review of the genesis geochronology and geological significance of hydrothermal copper and associated metals deposits in the great xing an range ne china abstract the great xing an range located in the eastern mongolia hinggan orogenic belt ne china hosts numerous endogenous base and precious metal mineral deposits the hydrothermal copper and associated metals deposits in this area can be divided into three genetic types based on their geology and geochronology porphyry cu mo high sulfidation cu ag and cu sn epithermal and cu fe skarn all of these mineral deposits barring the cu sm epithermal deposits are closely related to high k calc alkaline i type granitic magmatism the eastern part of the area hosts porphyry copper deposits that generally formed around 180 170 ma with a few deposits formed at 485 ma whereas high sulfidation epithermal copper silver deposits in the central great xing an range formed at 245 ma the west of the study area hosts high sulfidation epithermal cu sn deposits that formed at 150 135 ma and are related to a type granites skarn deposits are associated with the epithermal and porphyry deposits described above and formed at 180 160 and 150 135 ma the geodynamic setting of the region during these mineralizing events is consistent with early paleozoic collision between the xing an massif and the songnen terrane late permian collision between the north china craton ncc and the heilongjiang plate middle jurassic collision between the siberian plate and the ncc epicontinental aggradational belt and crustal extension and thinning during an early cretaceous collisional orogenic event this indicates that the mineral deposits formed in an intracontinental transitional orogenic or post orogenic extensional tectonic setting

origin of the wunugetushan porphyry cu mo deposit inner mongolia ne china constraints from geology geochronology geochemistry and isotopic compositions abstract the wunugetushan porphyry cu mo deposit is located in the southeastern margin of the mongol okhotsk orogenic belt and in the northwestern segment of the great xing an range ne china the orebodies of this deposit are mainly hosted in the monzogranitic porphyry stock and in contact with the granitic porphyry dyke and biotite granite batholith the shrimp zircon u pb dating of the granitic porphyry dyke yielded ages of 201 4 3 1 ma 2 mswd 1 5 these results indicate that the magmatism in the wunugetushan area might have occurred at ca 201 ma in the early jurassic and that the mineralization age ca 181 ma of this deposit is later than the age of intrusive granitic porphyry in the area geochemically the wunugetushan granitoids belong to high k calc alkaline and shoshonitic series enriched in k rb nd and pb and depleted in sr nb ti and p with negative eu anomalies in situ hf isotopic analyses of zircons using la mc icp ms indicate that the ehf t values for zircons from a granitic porphyry sample vary from 2 4 to 11 8 and that the corresponding crustal model ages tdmc vary from 483 to 1088 ma the least altered monzogranitic porphyry granitic porphyry and biotite granite yielded relatively uniform end t values from 1 0 to 0 6 and low 87sr 86sr i ratios ranging from 0 704387 to 0 708385 the geochemical and sr nd hf isotopic data for the granitoids indicate that the source magma for these rocks could be derived from a juvenile lower crust the 34s values of sulfides show a narrow range 0 76 to 3 20 similar to those of magmatic sulfur further implying a lower crust origin based on the results of this study and the regional geodynamic evolution it is proposed that the formation of the wunugetushan deposit and associated granitoids should be linked to the southeastward subduction of the mongol okhotsk oceanic plate beneath the erguna massif during the early jurassic and that the monzogranitic porphyry intrusions in wunugetushan area probably provided important ore metals responsible for the large scale cu mo mineralization

petrogenesis and geodynamic setting of granitoids at machangqing cu mo au deposit western yangtze craton southwestern china constraints from zircon u pb and molybdenite re os geochronology lu hf isotopes and geochemistry the machangqing cu mo au deposit is located in the central part of the jinshajiang red river belt in the sanjiang orogen which lies across the qiangtang terrane and western yangtze craton sou

giant porphyry deposits characteristics distribution and tectonic controls more than half of the 25 largest known porphyry copper deposits defined in terms of contained copper metal formed during three time periods the paleocene to eocene eocene to oligocene and middle miocene to pliocene these giant deposits are clustered within three provinces central chile northern chile and southwest arizona northern mexico other giant deposits occur in montana utah panama peru argentina irian jaya mongolia and iran compressive tectonic environments thickened continental crust and active uplift and erosion were associated with the formation of many of these deposits calc alkalic magmas are most favorable for the formation of giant porphyry copper deposits although several of the largest systems are associated with high k calc alkalic intrusions the 25 largest gold rich porphyry deposits are concentrated in the southwest pacific and south america with other occurrences in eurasia british columbia alaska and new south wales many of the deposits formed in the last 13 m y the largest of the deposits are associated with high k calc alkalic intrusions many calc alkalic porphyritic intrusions have also produced giant gold rich porphyries in the last 20 m y the formation of giant porphyry copper molybdenum and copper gold deposits in the circum pacific region has been closely associated with subduction of aseismic ridges seamount chains and oceanic plateaus beneath oceanic island and continental arcs in several examples these tectonic perturbations have promoted flat slab subduction crustal thickening uplift and erosion and adakitic magmatism coeval with the formation of well endowed porphyry and or epithermal mineral provinces similar tectonic features are inferred to be associated with the giant porphyry copper molybdenum provinces of northern chile eocene oligocene and southwest united states cretaceous paleocene topographic and thermal anomalies on the downgoing slab appear to act as tectonic triggers for porphyry ore formation other factors such as sutures in the overriding plate permeability architecture of the upper crust efficient processes of ore transport and deposition and in some cases formation and preservation of supergene enrichment blankets are also vital for the development of high grade giant ore deposits a low grade geochemical anomaly may be the final product of mineralization if ore forming processes do not operate efficiently even in the most favorable geodynamic settings

the genesis of the ores and intrusions at the yuhai cu mo deposit in eastern tianshan nw china constraints from geology geochronology geochemistry and hf isotope systematics abstract the yuhai porphyry cu mo deposit is located in the eastern tianshan orogenic belt of the southern central asian orogen belt being an economically important porphyry cu deposit in nw china the deposit comprises sixteen buried orebodies that are predominantly associated with dioritic and granodioritic intrusions and are structurally controlled by roughly ne trending faults la icp ms zircon u pb dating yielded crystallization ages of 441 6 2 5 ma mswd 0 03 n 24 for diorite and 430 4 2 9 ma mswd 0 04 n 19 and 430 3 2 6 ma mswd 0 09 n 24 for granodiorite in situ zircon hf isotope data on a diorite sample show e hf t values from 8 7 to 18 6 and two granodiorite samples exhibit similar e hf t values from 12 6 to 19 6 and 12 6 to 18 9 respectively the dioritic and granodioritic intrusions belong to a low k tholeiite series and are relatively enriched in large ion lithophile elements k ba pb and sr and are depleted in high field strength elements th nb ta and ti moreover these intrusions have high sio 2 al 2 o 3 and mgo contents low na 2 o p 2 o 5 and tio 2 contents low nb ta ratios and slightly positive eu anomalies re os dating of molybdenite intergrowth with chalcopyrite yielded a well constrained 187 re 187 os isochron age of 351 7 2 9 ma mswd 1 5 with a weighted average age of 355 7 2 4 ma mswd 0 69 ma indicating that the yuhai cu mo deposit is younger than the intrusion of the diorite and granodiorite combined with the regional geological history and above mentioned data we suggest that the yuhai intrusions were most likely derived from the partial melting of mantle components that were previously metasomatized by slab melts formed by the northward subduction of the ancient tianshan ocean plate beneath the dananhu tousuquan island arc during the silurian to carboniferous under the subduction related tectonic setting the metasomatized mantle magma was emplaced into the shallow crust and induced the formation of the early carboniferous yuhai cu mo deposit and the hydrothermal fluids of enriched sulfides probably played an important role in the cu mo mineralization

early jurassic porphyry copper mineralization in ne china a case study of the yanghuidongzi deposit abstract the yanghuidongzi cu deposit is located in the southeastern part of heilongjiang province in ne china and represents one of the few known early jurassic porphyry cu deposits within the eastern edge of the xing an mongolia orogenic belt here we present new whole rock major and trace element and sr nd isotopic data zircon u pb and hf isotopic data and molybdenite re os data for units associated with the deposit laser ablation inductively coupled plasma mass spectrometry la icp ms dating of zircons from the granodiorite porphyry in the study area yielded ages of 191 0 1 1 and 191 2 1 0 ma that are interpreted to be the emplacement age of this intrusion the molybdenite re os dating undertaken during this study yielded model ages of 192 7 187 0 ma an isochron age of 188 2 3 8 ma and a weighted mean model age of 190 2 2 6 ma representing the timing of formation of the cu mineralization in this area the yanghuidongzi granodiorite porphyry contains relatively high concentrations of sio 2 68 88 72 49 wt al 2 o 3 15 37 16 31 wt and sr 230 479 ppm but relatively low concentrations of y 7 97 9 87 ppm and yb 0 72 0 85 ppm suggesting that this intrusion has an adakitic affinity combining this with the positive end t 0 7 1 1 and ehf t values 4 0 6 9 low mg values 41 50 and the low concentrations of mgo 0 86 1 22 wt cr 3 17 4 37 ppm and ni 2 11 4 20 ppm within this intrusion suggests it formed from a magma generated by the partial melting of juvenile lower crustal material during the early jurassic subduction of the paleo pacific plate

ore genesis and fluid evolution of the daheishan giant porphyry molybdenum deposit ne china abstract the daheishan giant porphyry mo deposit is located at the eastern segment of the caob ne china the ore bearing intrusion of daheishan deposit is a jurassic granitic complex that includes changgangling biotite granodiorite qiancuoluo seriate granodiorite and qiancuoluo granodioritic porphyry mineralization consists of disseminated breccia and veined types the hydrothermal fluids show significant magmatic signatures as evidenced by the hydrogen and oxygen isotopic compositions of quartz and sulfur isotopic characteristics of ores consistence of lead isotopic compositions of the sulfides and the daheishan intrusive complex further indicate a close relationship between the mineralization and magma the fluid inclusions in quartz comprise of predominant aqueous two phase as well as gas rich fluid inclusions and a small number of daughter mineral bearing inclusions the gas species in the fluid inclusions are h2o co2 n2 ch4 c2h6 ar and minor h2s the liquid compositions are so42 cl na k ca2 and mg2 raman spectroscopy on individual fluid inclusions reveals a main gaseous composition of h2o minor h2s and co2 the fluid system in daheishan mo deposit can be described as nacl kcl h2o type fluid inclusion microthermometry reveals subsolidus homogenization temperatures for fluid inclusions in the magmatic quartz phenocrysts th 400 450 c salinities 21 eq wt suggesting an obliteration of higher temperature history of the porphyry system by the superimposed processes most of the mineralization occurred at temperature range of 220 360 c or higher the temperature and salinity decreased to 100 170 c and 0 15 eq wt respectively when the hydrothermal fluid activities were gradually ending no distinct evolution pattern based on the homogenization temperature or stable isotopic analyses is observed among the different mineralization stages mineralization was supposed to be related to the multi phased boiling of fluids instead of the gradual cooling of fluids pressure may be more critical than temperature in controlling the precipitation of molybdenite

geology and ore fluid geochemistry of the jinduicheng porphyry molybdenum deposit east qinling china abstract jinduicheng deposit is a giant mesozoic porphyry mo system deposit in the east qinling molybdenum belt shaanxi province china the mineralization is associated with the i type jinduicheng granite porphyry both the porphyry stock and country rocks underwent intense hydrothermal alteration the alteration with increasing distance from the parent intrusion changes from silicification through potassic and phyllic assemblages carbonation to propylitic assemblages molybdenite the dominant ore mineral occurs in veinlets most of which are hosted by the altered country rocks with less than 25 of the ore in the porphyry body the hydrothermal system comprises four stages including pre ore quartz and k feldspar two ore stages of quartz k feldspar molybdenite and pb and zn bearing sulfides and post ore quartz and carbonate six main types of primary fluid inclusions are present in hydrothermal quartz including two phase aqueous one phase aqueous three phase co 2 bearing co 2 dominated fluid inclusions gas inclusions and melt inclusions the homogenization temperatures of fluid inclusions range from 210 to 290 c in the pre ore stage 150 310 c in ore stage i 150 360 c in the ore stage ii and 195 325 c in the post ore stage quartz estimated salinities of the ore forming fluids range from 6 9 to 13 5 4 3 to 12 3 6 2 to 12 4 and 3 4 to 9 9 wt nacl equiv in stages 1 4 respectively the 34 s values of pyrite in the two ore stages range from 2 8 to 4 3 whereas the 34 s values of molybdenite range from 2 9 to 6 2 the data suggest both magmatic and crustal sources of sulfur the d and 18 o values for the hydrothermal fluids are 57 2 to 84 4 and 8 0 to 3 2 respectively the fluid inclusion and stable data indicate that the pre ore hydrothermal fluids were mostly of magmatic origin but the fluids responsible for ore deposition were mixed magmatic and meteoric and eventually meteoric water dominated the system in the post ore stage

geochronological isotopic and mineral geochemical constraints on the genesis of the diyanqinamu mo deposit inner mongolia china abstract the diyanqinamu mo deposit located in central inner mongolia in china is a newly discovered mo deposit due to the lack of detailed deposit scale studies the metallogenesis of the deposit has been a matter of debate in this study petrography zircon u pb geochronology sr nd and pb isotopes and apatite mineral geochemistry have been used to constrain the genesis of the diyanqinamu mo deposit petrographic evidence indicates that the granites in the diyanqinamu deposit have experienced fluid exsolution as demonstrated by the corroded quartz in the porphyritic granites skeletal quartz in the aplitic granites and the unidirectional solidification texture ust in the apex of the aplitic granites sr and nd isotopic data of the purple fluorite from the fluorite molybdenite veins showing the 87sr 86sr i 0 7046 0 7052 avg 0 7048 and end t values 2 4 3 8 avg 3 3 are similar to those of the porphyritic and aplitic granites this similarity implies that the mo ore forming fluids may have been derived from the granitic magmas the hypothesis is further supported by the fluorine content 3 79 5 48 wt avg 4 53 wt in apatite from the porphyritic granites and the widely distributed fluorite in the hydrothermal alteration mineral assemblages which indicate that the porphyritic granites contain high f content and the hydrothermal fluids are also f rich petrographic observation also shows that magnetite occurs commonly in the hydrothermal mineral assemblages indicating that the hydrothermal fluids are characterized by high oxygen fugacity fo2 it is important to note that the intruding granites are essentially barren and the mo is mainly hosted in the andesite and volcaniclastic rocks in comparison pb isotopic compositions of molybdenite are similar to those of both the andesite and k feldspar from the porphyritic granites which suggests that both the intruding granites and ore hosting andesite have contributed to the ore forming materials this hypothesis is further supported by the abnormally high mo for the andesite our new evidence suggests that the diyanqinamu mo deposit may have formed in a post collisional extensional environment ore forming materials may have been derived mainly from the granites and minimally from the host rocks the ore fluids are characterized by high fo2 and being f rich and the trigger for the mo mineralization has been attributed to the reduction of fo2 and or temperature for the ore fluids

geochronology and geochemistry of the wunugetushan porphyry cu mo deposit in ne china and their geological significance abstract the wunugetushan porphyry cu mo deposit is located in the manzhouli district of ne china on the southern margin of the mesozoic mongol okhotsk orogenic belt concentric rings of hydrothermal alteration and cu mo mineralization surround an early middle jurassic monzogranitic porphyry the cu mo mineralization is clearly related to the quartz potassic and quartz sericite alteration molybdenite re os and groundmass 40 ar 39 ar of the host porphyry dates indicate that the ore formation and porphyry emplacement occurred at 177 6 4 5 ma and 179 0 1 9 ma respectively geochemically the host porphyry of the deposit is characterized by strong lree hree fractionation enrichment in lile ba rb u th and pb and depletion of hfse nb ta ti and hree the sr nd pb isotopic compositions of the porphyry display an varied initial 87 sr 86 sr i ratio a positive e nd t values and high 206 pb 204 pb t 207 pb 204 pb t and 208 pb 204 pb t ratios these data indicate that the magmatic source of the host porphyry comprised two end members lithospheric mantle metasomatized by fluids derived from the subducted slab and continental crust we infer that the primitive magma of the host porphyry was derived from crust mantle transition zone based on regional geology and geochemistry of the host porphyry the wunugetushan deposit is suggested to form in a continental collision environment after closure of the mongol okhotsk ocean

linear to non linear relationship between vein spacing and layer thickness in centimetre to decimetre scale siliciclastic multilayers from the high ardenne slate belt belgium germany abstract typical spacing distributions have frequently been described for fractures in thin sedimentary layers 40 cm vein spacing tends to increase to a maximum value becoming more or less independent of layer thickness the resemblance with fracture spacing suggests that in an unfractured rock vein saturation can occur high fluid pressures are responsible for vein nucleation but the stress state around the initial veins controls the spacing pattern subsequently in a vein saturated rock or the existing veins will thicken by the process of crack sealing or a new cross cutting vein generation will develop in case the regional stress field changes relatively with respect to the existing veins

spatial temporal relationships of mesozoic volcanic rocks in ne china constraints on tectonic overprinting and transformations between multiple tectonic regimes abstract la icp ms zircon u pb ages and geochemical data are presented for the mesozoic volcanic rocks in northeast china with the aim of determining the tectonic settings of the volcanism and constraining the timing of the overprinting and transformations between the paleo asian ocean mongol okhotsk and circum pacific tectonic regimes the new ages together with other available age data from the literature indicate that mesozoic volcanism in ne china can be subdivided into six episodes late triassic 228 201 ma early middle jurassic 190 173 ma middle late jurassic 166 155 ma early early cretaceous 145 138 ma late early cretaceous 133 106 ma and late cretaceous 97 88 ma the late triassic volcanic rocks occur in the lesser xing an zhangguangcai ranges where the volcanic rocks are bimodal and in the eastern heilongjiang jilin provinces where the volcanics are a type rhyolites implying that they formed in an extensional environment after the final closure of the paleo asian ocean the early middle jurassic 190 173 ma volcanic rocks both in the erguna massif and the eastern heilongjiang jilin provinces belong chemically to the calc alkaline series implying an active continental margin setting the volcanics in the erguna massif are related to the subduction of the mongol okhotsk oceanic plate beneath the massif and those in the eastern jilin heilongjiang provinces are related to the subduction of the paleo pacific plate beneath the eurasian continent the coeval bimodal volcanic rocks in the lesser xing an zhangguangcai ranges were probably formed under an extensional environment similar to a backarc setting of double direction subduction volcanic rocks of middle late jurassic 155 166 ma and early early cretaceous 145 138 ma age only occur in the great xing an range and the northern hebei and western liaoning provinces limited to the west of the songliao basin and they belong chemically to high k calc alkaline series and a type rhyolites respectively combined with the regional unconformity and thrust structures in the northern hebei and western liaoning provinces we conclude that these volcanics formed during a collapse or delamination of a thickened continental crust related to the evolution of the mongol okhotsk suture belt the late early cretaceous volcanic rocks widely distributed in ne china belong chemically to a low to medium k calc alkaline series in the eastern heilongjiang jilin provinces i e the eurasian continental margin and to a bimodal volcanic rock association within both the songliao basin and the great xing an range the volcanics in the eastern heilongjiang jilin provinces formed in an active continental margin setting related to the subduction of the paleo pacific plate beneath the eurasian continent and the bimodal volcanics formed under an extensional environment related either to a backarc setting or to delamination of a thickened crust or both late cretaceous volcanics limited to the eastern heilongjiang jilin provinces and the eastern north china craton ncc consist of calc alkaline rocks in the eastern heilongjiang jilin provinces and alkaline basalts in the eastern ncc suggesting that the former originated during subduction of the paleo pacific plate beneath the eurasian continent whereas the latter formed in an extensional environment similar to a backarc setting taking all this into account we conclude that 1 the transformation from the paleo asian ocean regime to the circum pacific tectonic regime happened during the late triassic to early jurassic 2 the effect of the mongol okhotsk suture belt on ne china was mainly in the early jurassic middle late jurassic and early early cretaceous and 3 the late early cretaceous and late cretaceous volcanics can be attributed to the subduction of the paleo pacific plate beneath the eurasian continent

geodynamics and metallogeny of the central eurasian porphyry and related epithermal mineral systems a review abstract major porphyry cu au and cu mo deposits are distributed across almost 5000 km across central eurasia from the urals mountains in russia in the west to inner mongolia in north eastern china these deposits were formed during multiple magmatic episodes from the ordovician to the jurassic they are associated with magmatic arcs within the extensive subduction accretion complex of the altaid and transbaikal mongolian orogenic collages that developed from the late neoproterozoic through the palaeozoic to the jurassic intracratonic extension the arcs formed predominantly on the palaeo tethys ocean margin of the proto asian continent but also within two back arc basins the development of the collages commenced when slivers of an older proterozoic subduction complex were rifted from an existing cratonic mass and accreted to the palaeo tethys ocean margin of the combined eastern europe and siberian cratons subduction of the palaeo tethys ocean beneath the karakum and altai tarim microcontinents and the associated back arc basin produced the overlapping late neoproterozoic to early palaeozoic tuva mongol and kipchak magmatic arcs contemporaneous intra oceanic subduction within the back arc basin from the late ordovician produced the parallel urals zharma magmatic arc and separated the main khanty mansi back arc basin from the inboard sakmara marginal sea by the late devonian the tuva mongol and kipchak arcs had amalgamated to form the kazakh mongol arc by the mid palaeozoic the two principal cratonic elements the siberian and eastern european cratons had begun to rotate relative to each other drawing in the two sets of parallel arcs to form the kazakh orocline between the two cratons during the late devonian to early carboniferous the palaeo pacific ocean began subducting below the siberian craton to form the sayan transbaikal arc which expanded by the permian to become the selanga gobi khanka arc by the middle to late permian as the kazakh orocline continued to develop both the sakmara and khanty mansi back arc basins were closed and the collage of cratons and arcs were sutured by accretionary complexes during the permian and triassic the north china craton approached and docked with the continent closing the mongol okhotsk sea an embayment on the palaeo pacific margin to form the mongolian orocline subduction and arc building activity on the palaeo pacific ocean margin continued to the mid mesozoic as the indosinian and yanshanian orogens significant porphyry cu au mo and au cu deposits were formed during the ordovician in the kipchak arc e g bozshakol cu au in kazakhstan and taldy bulak porphyry cu au in kyrgyzstan silurian to devonian in the kazakh mongol arc e g nurkazgan cu au in kazakhstan and taldy bulak levoberezhny au in kyrgyzstan devonian in the urals zharma arc e g yubileinoe au cu in russia devonian in the kazakh mongol arc e g oyu tolgoi cu au and tsagaan suvarga cu au in mongolia carboniferous in the kazakh mongol arc e g kharmagtai au cu in mongolia tuwu yandong cu au in xinjiang china koksai cu au kounrad cu au and the aktogai group of cu au deposits in kazakhstan carboniferous in the valerianov beltau kurama arc e g kal makyr dalnee cu au in uzbekistan benqala cu au in kazakhstan late carboniferous to permian in the selanga gobi khanka arc e g duobaoshan cu au in inner mongolia china triassic in the selanga gobi khanka arc and jurassic in the selanga gobi khanka arc e g wunugetushan cu mo and jiguanshan mo in inner mongolia china in addition to the tectonic geologic and metallogenic setting and distribution of porphyry cu au mo mineralisation within central eurasia the setting geology alteration and mineralisation at each of the deposits listed above is described and summarised in table 1

distribution of porphyry deposits in the eurasian continent and their corresponding tectonic settings in the eurasian continent there are three huge metallogenic belts of cu and mo porphyry deposits comprising the paleozoic central asian ore belt in the north the tethyan eurasian ore belt of jurassic to cenozoic age in the southwest and the east margin ore belt of the eurasian continent of jurassic to cretaceous age in the east the latter is considered to be part of the vast circum pacific ore belt some of the main features of the spatial temporal distribution of cu and mo porphyry systems and related geodynamic processes of the three metallogenic belts are described in particular the key role of postsubduction related porphyry ore systems is emphasized comprising collisional and post collisional cu mo porphyry deposits during the geological history of the eurasian continent the recurrent feature of these ore systems and related felsic rocks is their derivation from partial melting of stagnant or residual oceanic slabs and mixing with a variable amount of crustal material during magma ascent to shallower levels 2013 published by elsevier ltd

a type granites in northeastern china age and geochemical constraints on their petrogenesis abstract a type granites are widely distributed in northeastern china ne china they were emplaced during three major episodes the permian late triassic to early jurassic and early cretaceous and evolved in different tectonic regimes according to their mineralogical and geochemical characteristics two subgroups of a type granites aluminous and peralkaline can be recognized the peralkaline subgroup contains alkali mafic minerals such as riebeckite arfvedsonite and sodic pyroxene while the aluminous subgroup contains annite and fe rich calcic or sodic calcic amphibole with respect to the aluminous subgroup the peralkaline granites contain higher rb ga and total rare earth elements ree but lower mgo cao al 2 o 3 ba and sr based on the discrimination criteria of eby geology 20 1992 641 the permian and late triassic to early jurassic a type granites belong to the a 2 post orogenic type whereas the early cretaceous granites are of the a 1 anorogenic type nd isotopic compositions of these a type granites indicate their derivation from a dominantly juvenile crustal source their origin is thought to have involved partial melting of an underplated lower crustal source because the generation of a type granites requires high melting temperature we propose models involving slab break off lithospheric delamination and extension the permian a type granites have the same age range as those in eastern junggar southern mongolia and central inner mongolia they occur along a major suture and form a narrow belt between the north china and siberian cratons we suggest that their formation was associated with post collisional slab break off the late triassic to early jurassic a type granites are likely to be the product of lithospheric delamination after the final collision of the major crustal blocks in the late paleozoic to early triassic the early cretaceous a type granites have an anorogenic affinity and were possibly associated with rifting in eastern china at this time associated with the onset of paleo pacific subduction consequently we conclude that the a type granites in ne china were generated at three different times involving multiple processes operative in different tectonic environments

hf isotopic compositions of the standard zircons and baddeleyites used in u pb geochronology abstract zircon and baddeleyite u pb geochronological dating is widely used in solid earth sciences and the advent of rapid in situ methods of analysis such sims and icp ms has re emphasized the importance of having uniform standards recently it has been shown that hf isotopic data can provide important information on these minerals since they contain high concentrations of hf but have low lu hf ratios which results in negligible age correction however the complex internal structures that result from multiple thermal events such as inherited cores and metamorphic overgrowths require that the hf isotopic data be measured with high spatial resolution however the isobaric interferences of 176 yb and 176 lu on 176 hf hamper the precise determination of the 176 hf 177 hf ratio during in situ laser ablation mc icpms analysis it is shown here that mass biases of yb yb and hf hf change with time during analyses and behave differently for solutions and solid material therefore it is suggested that the mean yb value of the individual spot be used to obtain the precise isotopic composition for in situ zircon and baddeleyite hf isotopic analyses for low yb hf 176 yb 177 hf yb value have little effect on the accuracy of the hf isotopic composition however the appropriate yb isotopic abundance is necessary for high yb hf 176 yb 177 hf 0 001 zircons and baddeleyites since the interference of 176 yb on 176 hf is significant using the mean yb value of the individual spot and newly published yb isotopic abundance data six standard zircons and two standard baddeleyites have been investigated using a neptune mc icpms with 193 nm laser for zircons the obtained 176 hf 177 hf ratios are 0 282307 31 2sd for 91500 0 282680 31 2sd for temora 0 281729 21 2sd for cz3 282177 17 2sd for cn92 1 0 282983 17 2sd for fm0411 and 281234 11 2sd for phalaborwa the baddeleyites from phalaborwa and sk10 2 have 176 hf 177 hf ratios of 0 281238 12 and 0 282738 13 2sd these results agree well with the values obtained by the solution method and indicate that these standards have different hf isotopic compositions in which the extremely low 176 lu 177 hf and 176 yb 177 hf values of cz3 zircon and phalaborwa baddeleyite make them excellent standards for machine calibration during in situ zircon hf isotopic measurement with the other standards being more suitable for the development of the correction method

geodynamic setting of mesozoic magmatism in ne china and surrounding regions perspectives from spatio temporal distribution patterns of ore deposits abstract north eastern china and surrounding regions host some of the best examples of phanerozoic juvenile crust on the globe however the mesozoic tectonic setting and geodynamic processes in this region remain debated here we attempt a systematic analysis of the spatio temporal distribution patterns of ore deposits in ne china and surrounding regions to constrain the geodynamic milieu from an evaluation of the available geochronological data we identify five distinct stages of ore formation 240 205 ma 190 165 ma 155 145 ma 140 120 ma and 115 100 ma the triassic 240 205 ma magmatism and associated mineralisation occurred during in a post collisional tectonic setting involving the closure of the paleo asian ocean the early mid jurassic 190 165 ma events are related to the subduction of the paleo pacific ocean in the eastern asian continental margin whereas in the erguna block these are associated with the subduction of the mongol okhotsk ocean from 155 to 120 ma large scale continental extension occurred in ne china and surrounding regions however the late jurassic magmatism and mineralisation events in these areas evolved in a post orogenic extensional environment of the mongol okhotsk ocean subduction system the early stage of the early cretaceous events occurred under the combined effects of the closure of the mongol okhotsk ocean and the subduction of the paleo pacific ocean the widespread extension ceased during the late phase of early cretaceous 115 100 ma following the rapid tectonic changes resulting from the paleo pacific oceanic plate reconfiguration