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1.
The Xingshan porphyry Mo deposit is located in the Lesser Xing’an Range–Zhangguangcai Range metallogenic belt, NE China. Mineralization occurred in granodioritic porphyry and monzogranite, which have zircon U–Pb ages of 171.7 ± 2.2 Ma and 170.9 ± 4.6 Ma, respectively. Molybdenite Re–Os dating indicates that Mo mineralization occurred at 167.3 ± 2.5 Ma. These geochronological data suggest that the magmatic and hydrothermal activities of the Xingshan Mo deposit happened during the Middle Jurassic in Mesozoic. Positive εHf values (6.2–11.6) and young TDM2 (473–826 Ma) of the monzogranite (XS-3) and granodioritic porphyry (XS-5) indicate that the source materials of Xingshan ore-bearing rocks are the juvenile crust, which mainly accreted on the Songnen block during the Meso-Neoproterozoic. Xingshan porphyry Mo deposits resulted from the magmatism and tectonism induced by the subduction of Paleo-Pacific Ocean. 相似文献
2.
The recently discovered polymetallic Shazigou Mo–W–Pb–Zn ore field is located at the northern margin of the North China Craton. This integrated metallogenic system is comprised of quartz vein mineralization in three deposits: Shazigou Mo–W, Jindouzishan Pb–Zn and Mantougou Pb–Zn. The total reserves are estimated to be 50 kt Mo, 626 t WO3, 244 kt Pb and 150 kt Zn. Molybdenite Re–Os dating of five quartz vein-type ores yielded a mean model age of 243.8 ± 1.6 Ma (MSWD = 0.81) and hydrothermal zircons yielded a concordant U–Pb age of 245 ± 2.6 Ma (MSWD = 0.65). These results suggest that the mineralization was formed in the early Triassic and could be related to Paleo-Asian Ocean subduction. Microthermometry and quartz fluid inclusion compositions indicate that fluids related to the Mo–W mineralization were mainly derived from magmatic sources and precipitated under relatively high temperature (280–340 °C) and salinity conditions (6–9 wt% NaCl equiv.), whereas subsequent Pb–Zn mineralization-related fluids may have been modified by metamorphic and meteoric waters. The discovery of the Shazigou ore field suggests conditions may be favourable for more extensive mineralization in the western Xilamulun Mo metallogenic belt at the northern margin of the North China Craton. 相似文献
3.
The super-large Shuangjianzishan Pb–Zn–Ag deposit is a newly discovered deposit located in the Huanggang–Ganzhuermiao polymetallic metallogenic belt of Inner Mongolia, NE China. The deposit's resource includes 0.026 Mt Ag, 1.1 Mt Pb, and 3.3 Mt Zn. The deposit is controlled by a NW-trending ductile shear zone and NE- and NW-trending faults in black pelite assigned to the lower Permian Dashizhai Formation. LREE enrichment, HREE depletion, Nb, Ta, P, and Ti depletion, and Zr and Hf enrichment characterize felsic magmatic rocks in the Shuangjianzishan Pb–Zn–Ag district. The ages of porphyritic monzogranite, rhyolitic crystal–vitric ignimbrite, and porphyritic granodiorite are 254–252, 169, and 130 Ma, respectively. Pyrite sampled from the mineralization has Re–Os isochron ages of 165 ± 7 Ma, which suggest the mineralization is associated with the ca. 169 Ma magmatism in the Shuangjianzishan district.Zircons extracted from the porphyritic granodiorite yield εHf(t) values of − 11.34 to − 1.41, with tDM2 dates of 1275–1901 Ma. The εHf(t) values of zircons in the rhyolitic crystal–vitric ignimbrite and the ore-bearing monzogranite porphyry are 7.57–16.23 and 10.18–15.96, respectively, and their tDM2 ages are 177–733 and 257–632 Ma, respectively. Partial melting of depleted mantle resulted in the formation of the ca. 254–252 Ma ore-bearing porphyritic monzogranite and the ca. 169 Ma rhyolitic crystal–vitric ignimbrite; dehydration partial melting of subducted oceanic crust resulted in the formation of the ca. 130 Ma porphyritic granodiorite. The porphyritic monzogranite was emplaced during the late stages of closure of the Paleo-Asian Ocean during the transformation from a collisional to extensional tectonic setting. The ca. 170 and ca. 130 Ma magmatism and mineralization in the Shuangjianzishan district are related to subduction of the Mongolia–Okhotsk Ocean and subduction of the Paleo-Pacific Ocean Plate, respectively. 相似文献
4.
The Luming porphyry Mo deposit and the Xulaojiugou skarn Pb–Zn deposit are located in the southeast Lesser Xing’an Range, NE China. They are about 15 km apart, and are both related to monzogranite. Mo orebodies in the Luming deposit are hosted within the medium- to fine-grained monzogranite, while Pb–Zn orebodies in the Xulaojiugou deposit are hosted by the contact zone between the medium-grained monzogranite and the marbles of the early Cambrian Qianshan Formation.LA-ICP-MS zircon U–Pb dating of the ore-related monzogranite in the Luming deposit yields crystallization age of 180.7 ± 1.6 Ma, and the medium-grained and porphyritic monzogranites from the Xulaojiugou deposit yield crystallization ages of 181.2 ± 1.1 Ma and 179.9 ± 1.0 Ma, respectively. Analyses of seven molybdenite samples from the Luming deposit display Re–Os isochron age of 177.9 ± 2.6 Ma. These results indicate that the mineralization in the Luming and Xulaojiugou deposits occurred at about 181–178 Ma. These two deposits are genetically linked and belong to a porphyry-skarn metallogenic system. Combined with the previously reported geochronological data for ore deposits in adjacent areas, we consider that the early Jurassic is an important epoch for Mo and Pb–Zn mineralization in the Lesser Xing’an Range.The monzogranites from the Luming and Xulaojiugou deposits are enriched in and Rb, Th, U, Pb and light rare earth elements (LREEs), and are depleted in Ba, Nb, Ta, P, Ti and Eu. They have positive εHf(t) values of 1.0–4.0 with two-stage Hf model ages (TDM2) of 868–1033 Ma. Whole-rock Sr and Nd isotopes show restricted ranges of initial compositions, with (87Sr/86Sr)i between 0.706346 and 0.707384 and εNd(t) between −3.5 and −1.8. These data indicate that their primary magmas originated from the partial melting of a depleted lithospheric mantle which had been metasomatized by subducted slab-derived fluids/melts. The early Jurassic magmatic–metallogenic events in the Lesser Xing’an Range are interpreted as a response to the subduction of the Paleo-Pacific Plate. 相似文献
5.
The Matou Mo(-Cu) deposit, located in the Yangtze Valley Metallogenic Belt of central-eastern China, is a typical porphyry-type Mo deposit. The orebodies at the deposit are hosted by Matou porphyritic granodiorite, which is the largest intrusive in the area. Quartz vein-type and disseminated sulfide mineralization are well developed in the porphyry and near its contact with Silurian sandstone. Crosscutting relationships indicate that porphyritic granodiorite is the oldest phase in the pluton, which is crosscut by a porphyritic diorite containing traces of chalcopyrite, and later dolerite dykes. These phases have U-Pb zircon dates of 147 ± 3, 140 ± 1 and 135 ± 1 Ma, which confirms the cross-cutting relationships observed in the field. A Re-Os molybdenite isochron age of 147 ± 4 Ma indicates that the porphyritic granodiorite is the source of the oldest Mo mineralization in the metallogenic belt and was formed during a change of the tectonic setting in the area, from an intracontinental orogeny to extensional tectonics. From 147 to 135 Ma, crust-mantle interaction played an important role in the formation of magmatic rocks at Matou. Systematic petrological and geochemistry investigations reveal that the three phases have a crust source with minor input from the mantle. Investigation of ore-forming fluid, H-O isotopes, S isotopes, and the Re content of molybdenite indicate that the ore-forming fluid and metals were derived from the lower crust. During the evolution of fluid from initial magmatic fluids (stage I) to ore-forming fluids (stage II), fluid boiling accompanied by the input of relatively cooler meteoric water led to the deposition of the Mo mineralization. 相似文献
6.
The Yidun Arc was formed in response to the westward subduction of Garze–Litang Ocean (a branch of Paleotethys) in the Late Triassic, where abundant porphyry Cu–Mo deposits (221–213 Ma) developed along the regional NW–SE sinistral faults and emplaced in the southern portion of the arc. The ore-related porphyries are mostly metaluminous or slightly peraluminous, belonging to shoshonitic high-potassium calc-alkaline I-type granites, with εHf(t) values of −6.64 to +4.12. The ore-bearing magmas were probably derived from the partial melting of subduction-metasomatic-enriched mantle, with the contamination of underplated mafic materials. The Late Cretaceous (88–80 Ma) highly fractionated I-type granite belt and related porphyry Cu–Mo deposits and magmatic-hydrothermal Cu–Mo–W deposits occur along approximately N–S-trending faults in the Yidun Arc. This belt extended across the Yidun Arc and Garze–Litang suture zone to the north and across the Yangtze Craton to the south, intruding the Late Triassic porphyry belt. The ore-related porphyries are characterized by high silica and high total alkalis, with enrichment in large ion lithophile elements (LILEs; Rb, U and K) and depletion in high field strength elements (HFSE; Nb, Ta, P and Ti) and Ba. They have lower εHf(t) values varying from −9.55 to −2.75, and significant negative Eu anomalies, indicating that the ore-bearing porphyritic magmas originated from ancient middle-upper crust. Two-stage magmatism and mineralization were superimposed in the Xiangcheng-Shangri-La district. Some ore deposits comprise two episodes of magmatism and associated mineralization such as both 207 ± 3.0 Ma granodiorite and 82.1 ± 1.2 Ma monzogranite intruded in the Xiuwacu deposit, causing Cu–Mo–W polymetallic mineralization. To date, 11 Late Triassic porphyry Cu deposits (e.g. the Pulang giant deposit with 5.1 Mt Cu), and five Late Cretaceous porphyry Cu–Mo (W) deposits (e.g. Tongchanggou Mo deposit with 0.59 Mt Mo) have been evaluated in the Xiangcheng-Shangri-La district. The continuity and inheritance of multiphase magmatism and the new understanding of superimposed mineralization will help to guide future exploration. 相似文献
7.
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. 相似文献
8.
The Fujiawu porphyry Cu–Mo deposit is one of several porphyry Cu–Mo deposits in the Dexing district, Jiangxi Province, Southeast China. New zircon SHRIMP U–Pb data yield a weighted mean 206Pb/238U age of 172.0 ± 2.1 and 168.5 ± 1.4 Ma from weakly altered granodiorite porphyry and quartz diorite porphyry, respectively. Two hydrothermal biotites from granodiorite porphyry give an Ar–Ar step-heating plateau age of 169.9 ± 1.8 and 168.7 ± 1.8 Ma. Hydrothermal apatite exsolved from altered biotite yields an isotope dilution thermal ionization mass spectrometry isochron age of 164.4 ± 0.9 Ma. The apatite age is similar to the ages obtained from hydrothermal rutile (165.0 ± 1.1 and 164.8 ± 1.6 Ma) and indicates that the magmatism and hydrothermal activity in the Fujiawu deposit occurred in the Middle Jurassic. Hydrothermal fluid circulation related to multiple stages of magma emplacement resulted in Cu–Mo mineralization in the Fujiawu porphyry deposit. The zircon SHRIMP U–Pb ages and the published molybdenite Re–Os age (170.9 ± 1.5 Ma) represent the timing of magma crystallization and Mo mineralization, whereas the rutile and apatite U–Pb ages reflect the timing of Cu mineralization following quartz diorite emplacement. The data suggest slow cooling after emplacement of the quartz diorite porphyry. 相似文献
9.
The newly discovered Yuanlingzhai porphyry molybdenum (Mo) deposit in southern Jiangxi province belongs to the group of Mo-only deposits in the Nanling region. The mineralization developed at contact zones between the Yuanlingzhai granite porphyry and Neoproterozoic metamorphic rocks of the Xunwu Formation. Precise LA–MC–ICPMS zircon U–Pb dating of the Yuanlingzhai porphyry, as well as the adjacent western Keshubei and eastern Keshubei granites, yielded ages of 165.49 ± 0.59 Ma, 159.68 ± 0.43 Ma, and 185.13 ± 0.52–195.14 ± 0.63 Ma, respectively. Molybdenite Re–Os isochron ages of the ores are 160 ± 1–162.7 ± 1.1 Ma, which is consistent with the age of large-scale W–Sn deposits in South China. The Yuanlingzhai porphyry is characterized by high K2O, P2O5, and A/CNK (1.33–1.59), and low CaO and Na2O. The rock shows relatively enriched LREE without significant Eu anomalies (Eu/Eu* = 0.80–0.90). Geochemical and mineralogical characteristics indicate that the ore-hosting porphyry is a typical S-type granite generated from the partial melting of crustal material with only minor mantle contribution. Both Harker and evolutionary discrimination diagrams indicate that the Yuanlangzhai and western Keshubei granites are not products of co-magmatic evolution. The Keshubei granites and Xunwu Formation were not significant sources for the components in the porphyry mineralization, but the Yuanlangzhai granite may have supplied some ore-forming material. However, the main ore-forming material was carried by fluids from deep sources, as demonstrated by fluid inclusion and stable isotope data from the molybdenum deposit. The Mo porphyry deposit formed in an extensional setting, and was possibly associated with Jurassic subduction of the Izanagi Plate. 相似文献
10.
The Shangjiazhuang Mo deposit is located on the Jiaodong Peninsula in eastern China, which is famous for the ca. 120 Ma “Jiaodong-type” Au deposits with total Au endowment of over 3000 t. In this paper, we discuss the deposit geology, mineralization age, and geochemical features of the host granodiorite of the Shangjiazhuang Mo orebody. Using this information, we aim to clarify the time and geodynamic mechanism for the Mo deposit, which is another constraint to understand the genesis of Au deposits. The Mo mineralization generally occurs as quartz–sulfide veins within the medium-grained Yashan granodiorite. The alteration consists of potassic alteration, silicification, sericitization, chloritization, and carbonatization with a weak unclear zonation. The ore minerals mainly include molybdenite, chalcopyrite, and pyrite. We measured Re–Os isotopes of molybdenite grains, which yielded a weighted mean model age of 116.9 ± 0.81 (MSWD = 1.03) and a well-constrained 187Re–187Os isochron age of 117.1 ± 1.4 Ma (MSWD = 1.6). These ages are slightly younger than the age of Au mineralization on the Jiaodong Peninsula. Rhenium contents of 5.84–29.99 ppm with an average of 16.4 ppm in molybdenites indicate a crustal source. Whole-rock geochemical compositions show that the granodiorite is high-K calc-alkaline and metaluminous to peraluminous. The samples show low Y contents from 8.2 to 10.5 ppm and Sr/Y ratios from 48.2 to 58.8, displaying an adakitic affinity. The Yashan granodiorite has high initial 87Sr/86Sr ratios of 0.7101 to 0.7104, low εNd(t) values of − 17.6 to − 16.7, and zircon εHf(t) values from − 24.8 to − 17.1, with corresponding Hf model ages of 2.7 to 2.2 Ga. These isotopic data, together with the adakitic affinity of the granodiorite, indicate that the parental magma was derived from ancient crust. Mafic microgranular enclaves (MME) that are contemporaneous with the host granodiorite show SiO2 contents of 57.98–58.41 wt% and depletion in Nb–Ta. The MMEs show enriched initial 87Sr/86Sr ratios of 0.7102 to 0.7106 and low εNd(t) values of − 17.3 to − 16.3. The MMEs are the products of mixing between the metasomatized lithospheric mantle-derived mafic magma and the ancient crust-derived felsic magma. The Early Cretaceous Mo mineralization (120–110 Ma) is slightly younger than the peak time of Au mineralization (126–120 Ma) on the Jiaodong Peninsula, but have a different spatial distribution which suggests different sources of Au and Mo. The “Jiaodong-type” Au deposits were probably related to the upwelling of metasomatized lithospheric mantle, while the Mo mineralization on the Jiaodong Peninsula may delineate a 120–110 Ma Mo metallogenic belt along the southern margin of the North China Craton with the East Qinling, which is related to the melting of ancient crustal sources. The subduction of the Paleo-Pacific slab and accompanying asthenospheric upwelling triggered upwelling of metasomatized lithospheric mantle, forming “Jiaodong-type” Au deposits. Subsequently, the ponding of mantle-derived magmas resulted in partial melting of ancient crust and associated Mo deposits. 相似文献
11.
Bangpu deposit in Tibet is a large but poorly studied Mo-rich (~ 0.089 wt.%), and Cu-poor (~ 0.32 wt.%) porphyry deposit that formed in a post-collisional tectonic setting. The deposit is located in the Gangdese porphyry copper belt (GPCB), and formed at the same time (~ 15.32 Ma) as other deposits within the belt (12 ~ 18 Ma), although it is located further to the north and has a different ore assemblage (Mo–Pb–Zn–Cu) compared to other porphyry deposits (Cu–Mo) in this belt. Two distinct mineralization events have been identified in the Bangpu deposit which are porphyry Mo–(Cu) and skarn Pb–Zn mineralization. Porphyry Mo–(Cu) mineralization in the deposit is generally associated with a mid-Miocene porphyritic monzogranite rock, whereas skarn Pb–Zn mineralization is hosted by lower Permian limestone–clastic sequences. Coprecipitated pyrite and sphalerite from the Bangpu skarn yield a Rb–Sr isochron age of 13.9 ± 0.9 Ma. In addition, the account of garnet decreases and the account of both calcite and other carbonate minerals increases with distance from the porphyritic monzogranite, suggesting that the two distinct phases of mineralization in this deposit are part of the same metallogenic event.Four main magmatic units are associated with the Bangpu deposit, namely a Paleogene biotite monzogranite, and Miocene porphyritic monzogranite, diabase, and fine-grained diorite units. These units have zircon U–Pb ages of 62.24 ± 0.32, 14.63 ± 0.25, 14.46 ± 0.38, and 13.24 ± 0.04 Ma, respectively. Zircons from porphyritic monzogranite yield εHf(t) values of 2.2–8.7, with an average of 5.4, whereas the associated diabase has a similar εHf(t) value averaging at 4.7. The geochemistry of the Miocene intrusions at Bangpu suggests that they were derived from different sources. The porphyritic monzogranite has relatively higher heavy rare earth element (HREE) concentrations than do other ore-bearing porphyries in the GPCB and plots closer to the amphibolite lithofacies field in Y–Zr/Sm and Y–Sm/Yb diagrams. The Bangpu diabase contains high contents of MgO (> 7.92 wt.%), FeOt (> 8.03 wt.%) but low K2O (< 0.22 wt.%) contents and with little fractionation of the rare earth elements (REEs), yielding shallow slopes on chondrite-normalized variation diagrams. These data indicate that the mineralized porphyritic monzogranite was generated by partial melting of a thickened ancient lower crust with some mantle components, whereas the diabase intrusion was directly derived from melting of upwelling asthenospheric mantle. An ancient lower crustal source for ore-forming porphyritic monzogranite explains why the Bangpu deposit is Mo-rich and Cu-poor rather than the Cu–Mo association in other porphyry deposits in the GPCB because Mo is dominantly from the ancient crust.The Bangpu deposit has alteration zonation, ranging from an inner zone of biotite alteration through silicified and phyllic alteration zones to an outer propylitic alteration zone, similar to typical porphyry deposits. Some distinct differences are also present, for example, K-feldspar alteration at Bangpu is so dispersed that a distinct zone of K-feldspar alteration has not been identified. Hypogene mineralization at Bangpu is characterized by the early-stage precipitation of chalcopyrite during biotite alteration and the late-stage deposition of molybdenite during silicification. Fluid inclusion microthermometry indicates a change in ore-forming fluids from high-temperature (320 °C–550 °C) and high-salinity (17 wt.%–67.2 wt.%) fluids to low-temperature (213 °C–450 °C) and low-salinity (7.3 wt.%–11.6 wt.%) fluids. The deposit has lower δDV-SMOW (− 107.1‰ to − 185.8‰) values compared with other porphyry deposits in the GPCB, suggesting that the Bangpu deposit formed in a shallower setting and is associated with a more open system than is the case for other deposits in this belt. Sulfides at Bangpu yield δ34SV-CDT values of − 2.3‰ to 0.3‰, indicative of mantle-derived S implying that coeval mantle-derived mafic magma (e.g., diabase) simultaneously supplied S and Cu to the porphyry system at Bangpu. In comparison, the Pb isotopic compositions (206Pb/204Pb = 18.79–19.28, 207Pb/204Pb = 15.64–15.93, 208Pb/204Pb = 39.16–40.45) of sulfides show that other metals (e.g., Mo, Pb, Zn) were likely derived mainly from an ancient crustal source. Therefore, the formation of the Bangpu deposit can be explained by a two-stage model involving (1) the partial melting of an ancient lower crust triggered by invasion of asthenospheric mantle-derived mafic melts that provide heat and metal Cu and (2) the formation of the Bangpu porphyry Mo–Cu system, formed by magmatic differentiation in the overriding crust in a post-collisional setting. 相似文献
12.
The Balkhash Metallogenic Belt (BMB) in Kazakhstan, Central Asia, with the occurrence of the super-large Kounrad and Aktogai, the large Borly porphyry Cu–Mo deposits, and the large Sayak skarn polymetallic ore-field, is one of the central regions of the Paleozoic Central Asian metallogenic domain and orogenic belt. In this study, newly obtained SHRIMP zircon U–Pb ages of nine samples and 40Ar/39Ar ages of six mineral samples (inclding hornblende, biotite and K-feldspar) give more detailed constraints on the timing of the granitic intrusions and their metallogeny. Porphyritic monzonite granite and tonalite porphyry from the Kounrad deposit yield U–Pb zircon SHRIMP ages of 327.3 ± 2.1 Ma and 308.7 ± 2.2 Ma, respectively. Quartz diorite and porphyritic granodiorite from the Aktogai deposit yield U–Pb SHRIMP ages of 335.7 ± 1.3 Ma and 327.5 ± 1.9 Ma, respectively. Porphyritic granodiorite and granodiorite from the Borly deposit yield U–Pb SHRIMP ages of 316.3 ± 0.8 Ma and 305 ± 3 Ma, respectively. Diorite, granodiorite, and monzonite from the Sayak ore-field yield U–Pb SHRIMP ages of 335 ± 2 Ma, 308 ± 10 Ma, and 297 ± 3 Ma, respectively. Hornblende, biotite, and K-feldspar from the Aktogai deposit yield 40Ar/39Ar cooling ages of 310.6 Ma, 271.5 Ma, and 274.9 Ma, respectively. Hornblende, biotite, and K-feldspar from the Sayak ore-field yield 40Ar/39Ar cooling ages of 287.3 ± 2.8 Ma, 307.9 ± 1.8 Ma, and 249.8 ± 1.6 Ma, respectively. The new ages constrain the timing of Late Paleozoic felsic magmatism to ∼336 to ∼297 Ma. Skarn mineralization in the Sayak ore-field formed at ∼335 and ∼308 Ma. Porphyry Cu–Mo mineralization in the Kounrad deposit and the Aktogai deposit formed at ∼327 Ma, and in the Borly deposit at ∼316 Ma. The Late Paleozoic regional cooling in the temperature range of ∼600 °C to ∼150 °C occurred from ∼307 to ∼257 Ma. 相似文献
13.
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 εHf(t) values from + 8.7 to + 18.6, and two granodiorite samples exhibit similar εHf(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 SiO2, Al2O3 and MgO contents, low Na2O, P2O5 and TiO2 contents, low Nb/Ta ratios, and slightly positive Eu anomalies. Re–Os dating of molybdenite intergrowth with chalcopyrite yielded a well-constrained 187Re–187Os 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. 相似文献
14.
The Donggebi Mo deposit located in NW China is a newly discovered, large, stockwork-type Mo deposit with ore reserves of 441 Mt @ 0.115% Mo. Ore bodies occur along faults and fractures at the external contact zone of a concealed porphyritic granite and volcaniclastic rocks of Gandun Formation, spatially associated with a fine-grained granite. Mo-bearing veins are mainly assemblages of volatile-rich K-feldspar-quartz-oxide, K-feldspar-quartz, polymetallic sulfides and calcite-quartz. Zircon LA-ICP-MS U–Pb dating yielded concordant ages of 234.6 ± 2.7 Ma and 231.8 ± 2.4 Ma for the porphyritic granite and the fine-grained granite, respectively; molybdenite Re–Os dating gave an isochron age of 234.0 ± 2.0 Ma. These ages further confirm an important and extensive magmatic-metallogenic event in Eastern Tianshan during the Triassic Indosinian orogeny. Whole-rock major and trace element analyses indicate that the granitic rocks associated with Mo mineralization are high in Si, K, Rb, Th, Nb, Ta, Ga and LREE, but low in P, Ti, Sr and Ba, belonging to high-K calc-alkaline granites with A-type features. Magma was likely derived from the re-melting of thickened lower crust in a post-collision compression environment in the Late Permian, experienced strong crystal fractionation and formed the large Donggebi Mo deposit under an intra-plate extension setting in the Early to Middle Triassic. 相似文献
15.
The Jinchang gold deposit is located in the easternmost portion of the Central Asian Orogenic Belt (CAOB), and represents one of the major gold districts in eastern Jilin–Heilongjiang provinces of China. The gold ore bodies are hosted mainly in altered Mesozoic granitoids, breccia pipes and ring and radial faults. Gold mineralization consists of alteration (stockwork in hydrothermally altered granites), breccia, and quartz-sulfide vein-types. Alteration assemblages around the alteration-style ore body show a vertical sequence of potassic, phyllic, and propylitic zones.In this study, we present U–Pb and Lu–Hf isotope data on zircons derived from mineralized granophyric granite, biotite monzogranite, granodiorite, and granite porphyry, and sericite Rb–Sr ages from the Jinchang gold deposit. The results show 206Pb/238U ages of 201 ± 3 Ma (MSWD = 1.1), 203 ± 4 Ma (MSWD = 1.4), 201 ± 5 Ma (MSWD = 2.1), and 110 ± 3 Ma (MSWD = 1.6), respectively. Sericite from the gold-mineralized phyllic-altered granodiorite and granite porphyry returns Rb–Sr isochron ages of 110 ± 4 Ma (MSWD = 1.04) and 107 ± 5 Ma (MSWD = 0.91), respectively. Our new data indicate that the gold mineralization at Jinchang took place at ca. 110 Ma and was temporally related to intrusion of the granite porphyry. Zircon ε Hf (200 Ma) values of the ca. 200 Ma granites vary from − 4.8 to + 8.1, with TCDM model ages of 727–1535 Ma, reflecting their derivation mainly by partial melting of juvenile Proterozoic crust. The gold-bearing 110 Ma granite porphyry returns ε Hf (110 Ma) values in the range of − 1.6 to + 9.8, with TCDM model ages of 542–1069 Ma, suggesting partial melts of juvenile Proterozoic crust with notable input of mantle components as compared to the ca. 200 Ma granites. Compiled oxygen (δ18OSMOW = − 0.7–10.1) and hydrogen (δDSMOW = − 99 to − 70) stable isotopic values of quartz from ores indicate that the ore-forming fluids were predominantly exsolved from magmas with minor amount of meteoric water in quartz-sulfide veins at the late stage. The Hf isotope data from the granite porphyry, integrated with the results from previous data on S and Pb isotopic composition of ores, constrain the source of ore-forming components as lower crust with discernible mantle inputs and wall rock assimilation. Our results have implications bearing on the widespread magmatism and metallogenic event during the Early Cretaceous time in East China, and link them to mantle upwelling that contributed both heat and volatiles for crustal melting and scavenging of metals which in turn were concentrated in upper crustal levels through exsolution for the magmas. 相似文献
16.
The Jiadanggen porphyry Cu–(Mo) deposit is newly discovered and located in the Eastern Kunlun metallogenic belt of Qinghai Province, China. Here, we present a detailed study of the petrogenesis, magma source, and tectonic setting of the mineralization causative granodiorite porphyry. The new data indicate that the granodiorite porphyry is characterized by high SiO2 (68.21–70.41 wt.%) and Al2O3, relatively high K2O, low Na2O, and low MgO and CaO concentrations, and is high-K calc-alkaline and peraluminous. The granodiorite porphyry has low Mg# (38–46) values that are indicative of no interaction between the magmas and the mantle. The samples that we have examined have low Nb/Ta (9.17–10.3) and Rb/Sr (0.28–0.39) ratios, which are indicative of crustal-derived magmas. Source region discrimination diagrams indicate that the magmas that formed the granodiorite porphyry were derived from melting of a mixed amphibolite source in the lower crust. The samples have ISr values of 0.70954–0.70979, εNd(t) values of − 8.3 to − 7.9, and t2DM ages ranging from 1644 to 1677 Ma. These indicate that the magmas that formed this intrusion were generated by melting of Mesoproterozoic lower crustal material. Higher K(Rb) contents of the samples indicate that the magma source is high potassium basaltic material in the lower crust, which could be derived from an enriched mantle source. LA-ICP-MS zircon U–Pb dating of the granodiorite porphyry yields a late Indosinian age (concordia age of 227 ± 1 Ma; MSWD = 0.31), which is close to the molybdenite Re–Os isochron age (227.2 ± 1.9 Ma), indicating further the close relationship between the granodiorite porphyry and the Cu–(Mo) mineralization. These samples are LREE and LILE (e.g., Rb, K, Ba, and Sr) enriched, and HFSE (e.g., Nb, Ta, P, and Ti) depleted, especially in P and Ti, similar to the characteristics of volcanic arc magmas. This intrusion most likely formed during the later stage of Indosinian deep subduction of oceanic slab. This was associated with underplating of mantle-derived magmas, which provided heat for crustal melting. Similar to the Jiadanggen granodiorite porphyry, Indosinian hypabyssal intermediate-felsic intrusive rocks, formed under subduction tectonism or a transitional regime from subduction to syn-collision, make up the most important targets for porphyry Cu(Mo) deposits in the Eastern Kunlun metallogenic belt. 相似文献
17.
This is a brief research report about the recently-discovered and currently being explored Dahutang tungsten deposit (or ore field) in northwestern Jiangxi, south-central China. The deposit is located south of the Middle–Lower Yangtze River valley Cu–Au–Mo–Fe porphyry–skarn belt (YRB). The mineralization is genetically associated with Cretaceous porphyritic biotite granite and fine-grained biotite granite and is mainly hosted within a Neoproterozoic biotite granodiorite batholith. The Dahutang ore field comprises veinlets-disseminated (~ 95% of the total reserve), breccia (~ 4%) and wolframite–scheelite quartz vein (~ 1%) ore styles. The mineralization and alteration are close to the pegmatite shell between the Cretaceous porphyritic biotite granite and Neoproterozoic biotite granodiorite and the three styles of ore bodies mentioned above are related to zoned hydrothermal alteration that includes greisenization, K-feldspar alteration, silicification, carbonatization, chloritization and fluoritization arranged in time (early to late) and space (bottom to top).Five samples of molybdenite from the three types of ores have been collected for Re/Os dating. The results show Re/Os model ages ranging from 138.4 Ma to 143.8 Ma, with an isochron age of 139.18 ± 0.97 Ma (MSWD = 2.9). The quite low Re content in molybdenite falls between 0.5 ppm and 7.8 ppm that is indicative of the upper crustal source. This is quite different from molybdenites in the YRB Cu–Au–Mo–Fe porphyry–skarn deposits that contain between 53 ppm and 1169 ppm Re, indicating a mantle source.The Dahutang tungsten system is sub-parallel with the YRB porphyry–skarn Cu–Au–Mo–Fe system. Both are situated in the north margin of the Yangtze Craton and have a close spatial–temporal relationship. This possibly indicates a comparable tectonic setting but different metal sources. Both systems are related to subduction of the Paleo-Pacific plate beneath the Eurasian continent in Early Cretaceous. The Cu–Au–Mo–Fe porphyry–skarn ores are believed genetically related to granitoids derived from the subducting slab, whereas the porphyry W deposits are associated with S-type granitoids produced by remelting of the upper crust by heat from upwelling asthenoshere. 相似文献
18.
The Lanping basin is a significant Pb–Zn–Cu–Ag mineralization belt of the Sanjiang Tethyan metallogenic province in China. Over 100 thrust-controlled, sediment-hosted, Himalayan base metal deposits have been discovered in this basin, including the largest sandstone-hosted Pb–Zn deposit in the world (Jinding), and several Cu ± Ag ± Co deposits (Baiyangping, Baiyangchang and Jinman). These deposits, with total reserves of over 16.0 Mt Pb + Zn, 0.6 Mt Cu, and 7000 t Ag, are mainly hosted in Meso-Cenozoic mottled clastic rocks, and strictly controlled by two Cenozoic thrust systems developed in the western and eastern segments of the Lanping basin.To define the metallogenic history of the study area, we dated nine calcite samples associated with copper sulfides from the Jinman Cu deposit by the Sm–Nd method and five molybdenite samples from the Liancheng Cu–Mo deposit by the Re–Os method. The calcite Sm–Nd age for the Jinman deposit (58 ± 5 Ma) and the molybdenite Re–Os age for the Liancheng deposit (48 ± 2 Ma), together with previously published chronological data, demonstrate (1) the Cu–Ag mineralization in the western Lanping basin mainly occurred in three episodes (i.e., ∼56–54, 51–48, and 31–29 Ma), corresponding to the main- and late-collisional stages of the Indo–Asian orogeny; and (2) the Pb–Zn–Ag (±Cu) mineralization in the eastern Lanping basin lacked precise and direct dating, however, the apatite fission track ages of several representative deposits (21 ± 4 Ma to 32 ± 5 Ma) may offer some constraints on the mineralization age. 相似文献
19.
The Eastern Qinling Orogen (EQO) is a major composite collisional zone located between the North China and the Yangtze cratons. This contribution combines geological and Hf–isotopic data from magmatic rocks associated with mineralization to gain insights into links between the crust architecture and metallogeny, and to focus exploration in the orogen.The new zircon U–Pb dates reported in this study are 434 ± 2 Ma for diorite, 433 ± 2 and 436 ± 2 Ma for monzogranite, and 454 ± 2 Ma for granodiorite in the Nanzhao area; 225 ± 2 Ma for syenite and 160 ± 1 Ma for monzogranite at Songxian; and 108 ± 1 and 102 ± 1 Ma for syenogranite in eastern Fangcheng. Combining our data with those from the entire EQO reveals seven major magmatic events since the Cambrian. These magmatic events took place during the Cambrian–Silurian associated with subduction, Early Devonian magmatism related to a collisional event, Early Permian to Late Triassic magmatism related to subduction, Late Triassic collisional magmatism, Late Triassic to Early Jurassic post–collision magmatism, and Jurassic–Cretaceous magmatism during intra–continental subduction.Lu-Hf isotopic data collected from granitic rocks for this study give εHf(t) values of: − 1.4 to 10.9 for diorite and monzogranite at Nanzhao; − 27.1 to − 15.6 for syenite and − 27.5 to − 25.1 for monzogranite at Songxian; and − 12.9 to − 3.4 for syenogranite in the eastern Fangcheng. Combining Hf isotopic data for the EQO from previous studies, we have evaluated the spatio–temporal distribution of Hf isotopic compositions. The resultant Hf isotopic maps highlight the location of the Kuanping Suture as an important tectonic boundary between the North China and the Yangtze cratons, which separates the EQO into a north part with an old and reworked lower crust and a southern part representing a juvenile lower crust.The Hf isotopic mapping of the EQO also provides information on the distribution of mineral deposits. Porphyry and porphyry–skarn Mo(–W) deposits are associated with magmatic rocks were emplaced in zones with low–εHf and high TDMc values representing old and reworked crustal components. In contrast, porphyry and porphyry–skarn Cu(–Mo) deposits are associated with magmatic rocks emplaced in domains with variable εHf and TDMc values characterized by dominantly reworked old crustal components with minor juvenile material. The magmatic source for the intrusions is characterized by low–εHf and high TDMc values, which are granite–related Mo or Pb–Zn–Ag mineralization. 相似文献
20.
Lai-min Zhu Guo-wei Zhang Yan-jing Chen Zhen-ju Ding Bo Guo Fei Wang Ben Lee 《Ore Geology Reviews》2011,39(1-2):46-62
East Qinling is the largest porphyry molybdenum province in the world; these Mo deposits have been well documented. In West Qinling, however, few Mo deposits have been discovered although granitic rocks are widespread. Recently, the Wenquan porphyry Mo deposit has been discovered in Gansu province, which provides an insight into Mo mineralization in West Qinling. In this paper we report Pb isotope compositions for K-feldspar and sulfides, S isotope ratios for sulfides, the results obtained from petrochemical study and from in situ LA-ICP-MS zircon U-Pb dating and Hf isotopes. The granitoids are enriched in LILE and LREE, with REE and trace element patterns similar to continental crust, suggesting a crustal origin. The Mg# (40.05 to 56.34) and Cr and Ni contents are high, indicating a source of refractory mafic lower crust. The εHf(t) values of zircon grains from porphyritic monzogranite range from ? 2.9 to 0.6, and from granitic porphyry vary from ? 3.3 to 1.9. The zircons have TDM2 of 1014 to 1196 Ma for the porphyritic monzogranite and 954 to 1224 Ma for the granitic porphyry, implying that these granitoids were likely derived from partial melting of a Late Mesoproterozoic juvenile lower crust. The Pb isotope compositions of the granitoids are similar to granites in South China, showing that the magma was sourced from the middle–lower crust in the southern Qinling tectonic unit. The Pb isotopic contrast between the Mo-bearing granitoids and ores shows that the Pb in the ore-forming solution was derived from fractionation of a Triassic magmatic system. δ34S values of sulfides are between 5.02 and 5.66‰, similar to those associated with magmatic-hydrothermal systems. LA-ICP-MS zircon U-Pb dating yields crystallization ages of 216.2 ± 1.7 and 217.2 ± 2.0 Ma for the granitoids, consistent with a previously reported molybdenite Re-Os isochron age of 214.4 ± 7.1 Ma. This suggests that the Mo mineralization is related to the late Triassic magmatism in the West Qinling orogenic belt. In view of these geochemical results and known regional geology, we propose that both granitoid emplacement and Mo mineralization in the Wenquan deposit resulted from the Triassic collision between the South Qinling and the South China Block, along the Mianlue suture. Since Triassic granitoid plutons commonly occur along the Qinling orogenic belt, the Triassic Wenquan Mo-bearing granitoids highlight the importance of the Triassic tectono-magmatic belt for Mo exploration. In order to apply this metallogenic model to the whole Qinling orogen, further study is needed to compare the Wenquan deposit with other deposits. 相似文献