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    Volume 40,2021 Issue 2
      第五届全国青年地质大会基础地质 专辑
    • SUN Xin-chun, WANG Huai-tao, LI Tong-guo, WEI Hai-feng, XU Lei, WANG Xiao-wei

      2021,40(2):171-184, DOI:

      Abstract:

      Zircon U-Pb chronology, rock geochemistry and Sr-Nd isotope have been investigated in this paper to determine the formation time, genesis of rock and formation environment of the granodiorite in Shuangfengshan. The results show that the formation age of Shuangfengshan granodiorite is 334.8±2.1 Ma (MSWD=1.2). The rocks have relatively high SiO2 (55.42%~65.53%), Na2O+K2O (7.42%~8.32%) and Al2O3 values (14.84%~17.53%), as well as K2O/Na2O ratios (0.16~0.29), which indicates that they are calc-alkaline, quasi-aluminum I-type granite. The rocks are rich in Rb, K, Nd, Zr and Hf, and relatively deficient in Nb, Ta, P, Sm and Ti. Nb/La (0.41~1.01) and Hf/Th (0.80~1.15) ratios are close to the data of typical island arc magmatic rocks. (87Sr/86Sr)i(0.706 0~0.709 5) and εNd(t)(-0.22~+0.52) show characteristics of crust-mantle interaction. Combined with regional geological research, the authors hold that Shuangfengshan granodiorite originated from the basaltic lower crust formed in the late Mesoproterozoic on the active continental margin under the underplating of Early Carboniferous basaltic magma, which was the response of the northward subduction of the back-arc basin represented by the Huitongshan-Zhangfangshan ophiolite.

    • YANG Zhen-xi, DING Shu-hong, ZHANG Jing, FAN Xin-xiang, KONG Wei-qiong, ZHAO Ji-chang, JING De-long

      2021,40(2):185-201, DOI:

      Abstract:

      Located on the southern margin of the Central Asian giant orogenic belt, the Beishan orogenic belt is one of the key areas for dissecting the accretionary tectonic process of the southern margin of the Central Asian orogenic belt. Researchers have a great controversy about the closing time of the Paleo-Asian Ocean and focus on whether the Devonian ancient Asian Ocean was still subducting or closed. In this study, the authors firstly identified a pluton with typical adakite characteristics in Heishantou area on the southern margin of the Beishan orogenic belt. The geochemical characteristics and zircon U-Pb chronology of the pluton were studied to discuss its genesis and geodynamic significance. The Heishantou pluton is dominated by granodiorite and partially consist of tonalite. The weighted average age of granodiorite LA-ICP-MS zircon U-Pb is 407.7±1.6 Ma. Geochemical data show that the Heishantou pluton belong to peraluminous, calc-alkaline series, with typical adakite characteristics:high silicon (SiO2=60.85%~67.81%), high alumina (Al2O3=15.59%~16.98%), low magnesium (MgO=0.55%~1.53%,Mg#=0.36~0.46), rich sodium and poor potassium (Na2O=2.65%~3.54%,K2O=1.09%~3.16%,Na2O/K2O=0.96~2.44), high Sr (Sr=253×10-6~487×10-6) low Y and Yb (Y=5.65×10-6~16.70×10-6,Yb=0.37×10-6~0.96×10-6) compositions, with high Sr/Y ratio (25.75~73.58). Their light rare earth elements (LREE) are enriched, with obvious light and heavy rare earth fractionation. The samples do not have obvious Eu anomaly (0.66~1.31, averaging 0.92). Moreover, trace element composition is characterized by enrichment of LILEs such as Rb, K, Th and U, and depletion of high field strength elements HSFEs such as Nb, Ta, Ti and P. Geochemical characteristics show that these adakites were formed by partial melting of the subducting oceanic crust, and the residual minerals of the crust sources might have been garnet and rutile. Based on this study and regional geological data, the authors hold that the Liuyuan Ocean (Paleo-Asian Ocean) was still in the subduction and collision stage during the Early Devonian and had the characteristics of "scissoring" closure from west to east. The upper limit of the closing time of the Paleozoic ocean basin is Early Carboniferous in the Beishan area.

    • YU Jun-peng, WANG Huai-tao, WANG Yu-xi, SUN Xin-chun, REN Wen-xiu, WEI Hai-feng, WANG Xiao-wei

      2021,40(2):202-216, DOI:

      Abstract:

      The Beishan area is an important part of the Central Asian Orogenic Belt. The Tanshanzidong basic complex located west of the Beishan Dashantou complex is an important carrier to reveal the late Paleozoic tectonic evolution on the southern margin of the Central Asian Orogenic Belt. This paper reports that the Tanshanzidong basic complex was emplaced with the zircon U-Pb age of 366.0±2.8 Ma. The rocks are characterized by SiO2 (47.83%~52.25%), K2O (0.12%~0.45%), Na2O (2.47%~3.19%), MgO (5.30%~9.22%) and the evolution from tholeiitic series to calc-alkaline series. The rocks are enriched in LREE with positive Eu anomalies, depleted in Nb, Ta, Zr, Ti and enriched in Rb, Ba, Sr, U, K, with the data Nb/La=0.23~0.46, Hf/Th=0.88~3.81, (87Sr/86Sr)i (0.704 8~0.704 9) and εNd(t) (+3.72~+4.30), suggesting that they were formed in the arc environment of active continental margin. Based on regional geology, the authors hold that the Tanshanzidong basic complex was the product of partial melting of depleted lithospheric mantle, which was replaced by the subduction fluid during the subduction of the northward subduction of back-arc basin represented by Huitongshan-Zhangfangshan ophiolite. These results provide a direct indication for the vertical growth of the crust caused by the late Devonian crust in the Central Asian Orogenic Belt.

    • LI Ying-lei, WU Guang, HE Hong-yun, CHEN Gong-zheng, YANG Fei, LI Tie-gang, SONG Guang-chao, XIAO Jian-wei

      2021,40(2):217-235, DOI:

      Abstract:

      Located in the eastern part of the Central Asian Orogenic Belt, the Jalaid Banner of Inner Mongolia is considered to be controlled by the eastern extension of Erlian-Hegenshan fault. It contains the key information of the subduction and extinction process of the Paleo-Asian Ocean. However, the studies of the Ophiolite mélange in this area are relatively weak. In this study, the ophiolite mélange, tonalites-trondhjemite and alkali feldspar granite assemblages related to island arc environment were found in Shabaertu region. Zircon U-Pb dating of the ophiolite mélange shows that their ages are 279.2±3.3 Ma and 278.2±1.7 Ma, respectively, indicating their emplacement in Early Permian. The ultramafic rocks have low SiO2 content (43.54%~46.38%), low Na2O and K2O values, but rich MgO, with Mg# of 89~94, showing the features of depleted mantle-transitional mantle, which originated from about 70% partial melting of garnet lherzolite. They belong to the supra-subduction zone type (SSZ). The tonalite-trondhjemite is a typical O-type adakite and belongs to the metaluminous and calc-alkaline series, relatively rich in Al2O3 and Sr (averaging 600.00×10-6), but low in Y (averaging 12.50×10-6) and Yb (averaging 1.18×10-6), suggesting that they originated from partial melting of the low-K oceanic crust basalts in subduction environment. The alkali feldspar granites are rich in silicon and alkali and low in iron and magnesium. They have high positive εHf(t) values (averaging + 18.9) and are located above the depleted mantle line, with the in-situ zircon Hf isotope one-stage and two-stage model age equal to or less than the crystallization ages of rocks, so they might have been derived from the island arc type juvenile crust. The Shabaetu ophiolite mélange represents the product of intra-oceanic subduction in the early Middle Permian, implying that the Paleo-Asian Ocean was not closed in the early Middle Permian, and the closure time should be at least after the Middle Permian.

    • DING Cheng-wu, DAI Pan, NIE Feng-jun, ZHANG Zhao-lu, PENG Yun-biao, ZHANG Geng-xin, LI Da-peng, SHEN Ying

      2021,40(2):236-256, DOI:

      Abstract:

      The Tugurige gold deposit is located in the western part of the Xing'an-Mongolia Orogenic Belt (XMOB). This paper describes the geochronologic and petrological-geochemical data of the intrusive rocks in the Tugurige gold deposit. The LA-ICP-MS U-Pb dating of zircons from syenogranite, granite, hornblendite and diorite in the Tugurige gold deposit yielded weighted mean 206Pb/238U ages of 264.5±1.4 Ma, 278.7±1.0 Ma, 280.6±1.3 Ma and 288.0±2.6 Ma respectively. The results show that the ages of gold mineralization (268~259 Ma) and syenogranite (276~265 Ma) are the same within error. Geological and geochronological evidence indicates that the syenogranite and gold mineralization have very close genetic relationships. The intrusive rocks in the Tugurige gold deposit are bimodal intrusive rocks, and belong to the high K calc-alkaline series. They are characterized by enrichment of large ion lithophile (Rb, Pb, K, Sr) and light rare earth elements (LREE) and depletion of high field strength elements (Nb, Ta, P, Ti). The intrusive rocks in the Tugurige gold deposit have some geochemical characteristics of the intrusive rocks in the subduction zone. This indicates that the source of these intrusive rocks was probably altered or affected by subduction events, but can not constrain their geological background. Combined with geological data available, the authors hold that the intrusions and gold mineralization in the Tugurige area were related to post-collisional extension of the Central Asian Orogenic Belt (CAOB).

    • SUN Yong-gang, LI Bi-le, WANG Yong-sheng, LI Liang, ZHANG Xue-hai, ZHAO Chang-ji, LI Ao-peng

      2021,40(2):257-268, DOI:

      Abstract:

      The subduction of the Paleo-Pacific Plate played an important role in the regional tectonic evolution of the eastern margin of the Eurasian continent, but the timing of this event remains ambiguous. To address this issue, this paper reports zircon U-Pb ages, zircon Hf isotopic compositions and petrogeochemical data of whole-rocks for the newly-found hornblende gabbro in Aohua Village, central Jilin Province. Zircon U-Pb dating shows that the hornblende gabbro was formed in Early Jurassic (180.3±2.3 Ma), and has high and uniform εHf(t) values (9.6~11.3). Petrogeochemical analyses show that the samples are characterized by low Si and Al, and high Fe, Mg, and Ca, enrichment of light rare earth elements and large-ion lithophile elements (e.g., Rb, Ba, U, K, and Sr), and depletion of heavy rare earth elements and high-field-strength elements (e.g., Nb, Ta, and Ti), and have weak negative Eu anomalies (δEu=0.67~0.98). They were derived from a depleted lithospheric mantle source that had previously been metasomatized by slab-derived fluids, with unapparent effects of fractional crystallization, crustal contamination and cumulation in the formation process. Combined with rock associations and spatial distri- bution of Early Mesozoic igneous rocks in the eastern part of Northeast China, the authors hold that the subduction of the Paleo-Pacific Plate beneath the Eurasian continent started in Early Jurassic, and the hornblende gabbro was formed in the back-arc setting which might have been closely related to the subduction of the Paleo-Pacific Plate.

    • CUI Fang-hua, XU Xue-chun, ZHENG Chang-qing, YAO Wen-gui, SHI Lu, WANG Lu-yuan

      2021,40(2):269-287, DOI:

      Abstract:

      The large-scale tectono-magmatism and mineralization during Mesozoic in eastern North China Craton resulted from the subduction of paleo-Pacific plate, although the starting time of subduction is still in dispute. In this study, the granitoids from Yaowangmiao-Mopan Mountain pluton in Xingcheng area, western Liaoning Province, were taken for systematic researches, including petrology, zircon U-Pb dating, geochemistry and zircon Hf isotopic analysis. Magmatic zircons yielded weighted mean ages of 193 Ma and 186 Ma, so the Yaowangmiao-Mopan Mountain pluton was emplaced during Early Jurassic. The granitic rocks are composed of quartz monzonite, granodiorite, monzogranite and syenogranite. All of these rocks have high total alkalis content and quasi-aluminous to weakly peraluminous characteristics, belonging to the high-K calc-alkaline series with geochemical characteristics similar to those of I-type granite. These rocks are enriched in LREE and K, Pb and depleted in Nb, Ta, Ti and P. The magmatic zircons of the Early Jurassic granitoids have negative εHf(t) (-12.94~-7.39) and ancient tDM2 values (2.05~1.69 Ga) which indicates that the primary magma was derived from the partial melting of ancient continental crust probably with the mixture of mantle source materials. The Early Jurassic granitic rocks in Xingcheng area of western Liaoning Province have rock assemblages and geochemical characteristics similar to the granitoids formed under the active continental margin related to the subduction of paleo-Pacific plate. The results in this study and regional geological data all indicate that the subduction of paleo-Pacific plate began during Late Triassic-Early Jurassic, and the Early Jurassic granitic magmatism resulted from the response to the subduction of paleo-Pacific plate in eastern North China Craton.

    • WANG Bin, SONG Ming-chun, HUO Guang, ZHOU Ming-ling, XU Zhong-hua, JIANG Lei, SONG Ying-xin, LI Jie

      2021,40(2):288-320, DOI:

      Abstract:

      Located at the junction of the southeastern margin of the North China Craton and the northeastern section of the Dabie-Sulu orogenic belt, the Jiaodong area is an ideal place for studying the transformation of regional tectonic mechanism and craton destruction. In this paper, the authors chose the Late Mesozoic granite as the research object, and carried out detailed petrographic, petrogeochemical, zircon LA-ICP-MS U-Pb geochronological and Sr-Nd isotope studies, focusing on the origin and evolution history of magma and geodynamic mechanism of regional diagenesis and mineralization. The results show that the emplacement ages of Jurassic continental crust remelted Linglong-type granite, Cretaceous crust-mantle mixed Guojialing-type granite and Weideshan-type granite are 163.2~157.9 Ma, 132.9~130.0 Ma, and 121.3~116.7 Ma, respectively, and the emplacement ages of Cretaceous Laoshan-type granite and vein rock are 125.0 Ma and 120.7 Ma, respectively, which are basically in line with the previous age test data. From Jurassic to Early Cretaceous, the chemical composition of granites evolved from high-potassium calc-alkaline series to shoshonite series, i.e., from peraluminous to metaluminous, trace element content evolved from high Ba-Sr to low Ba-Sr and from high Sr, low Y to low Sr and high Y, REE varied from no or weak positive Eu anomaly to significant negative Eu anomaly, and the type of granites varied from S-type to I-type and A-type. It shows the evolution trend from EM2 enriched mantle to EM1 enriched mantle, from enrichment to depletion or from lithosphere to asthenosphere. The Jiaodong area in the Late Mesozoic experienced the transformation from North China-Yangtze tectonic system to Eurasian-Pacific tectonic system and from compression mechanism to extension mechanism. The strong thermal-uplift extension structure in Early Cretaceous provided favorable conditions for large-scale gold mineralization.

    • BO Jun-wei, DING Zheng-jiang, SONG Ming-chun, QIU Kun-feng, SUN Feng-yue, JI Pan, XU Hong, ZHANG Ran

      2021,40(2):321-336, DOI:

      Abstract:

      The Liaoshang gold deposit is a newly discovered superlarge gold deposit on the northeast margin of Jiaolai Basin, which is different from "Jiaojia-type" and "Linglong-type" gold deposits by unique gold bearing minerals of pyrite and dolomite. The isotopic analysis of C, O for Au-bearing dolomite and S, Pb for Au-bearing pyrite from this deposit was carried out in order to identify the source of ore-forming materials and fluids for this new type gold deposit. The results show that the δ13CV-PDB and the δ18OV-SMOW values of dolomite range from -4.60‰ to -3.60‰ and 9.6‰ to 10.6‰, respectively. The δ34S values of Au-bearing pyrite vary from +7.2‰ to +9.4‰ with an average of +8.2‰. The results of Pb isotope from Au-bearing pyrite vary from 17.027 to 17.576, 15.435 to 15.503, and 37.706 to 38.205 for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios, respectively. Combined with the tectono-magmatic evolution in the Jiaolai Basin, the authors hold that the ore-bearing C-H-O fluids of the Liaoshang gold deposit mainly originated from the mantle. Furthermore, the meteoric water and crustal ore-forming materials were involved during the ascending process of ore-forming fluids, resulting in the characteristics of crust-mantle mixing. In conclusion, the genetic type of Liaoshang gold deposit should be the pyrite-carbonate vein type low temperature hydrothermal gold deposit.

    • WANG Fang-yue, ZHANG Wen-qi, DUAN Liu-an, WU Jie, GE Can, SUN He, GU Hai-ou, SHEN Rui-wen

      2021,40(2):337-346, DOI:

      Abstract:

      This paper reports a new type of high temperature REE-rich barytocalcite, which occurs in REE-enriched alkaline carbonate veins in Songxian County, Henan Province, East Qinling. The molecular formula of the studied barytocalcites is Ba1.04Ca0.81Sr0.14(CO3)2 (Sr-barytocalcite) based on Stoichiometric calculation using the major element compositions. LA-ICP-MS analyses show high concentrations of Na, K, Fe, Mn, Pb, Y and REEs in the barytocalcite. The total REE concentrations of the barytocalcites are up to 4 080×10-6, which generally show LREE-enriched and HREE-depleted patterns. Contrasting to sedimentary barytocalcite formed in low temperature, backscattered electron images suggest that the studied barytocalcites have two types of high-temperature textures intergrowing with aegirine augite or with quartz + calcite + apatite. The intergrowth of orthomorphic barytocalcite with primary calcite suggests that they were formed in the early stage of alkaline melt evolution, likely crystallized in a carbonate and silicate immiscible environment. The later stage calcites were found in barytocalcites and aegirine augites in patch shape, implying a carbonate metasomatic stage. The assemblage of aegirine augite + K-feldspar + albite + pyroxene + apatite +calcite + quartz + barytocalcite is consistent with that in carbonatites. The features of high Ba, Sr and REE content in the studied carbonatites are also of high similarity to well-known large-scale REE-rich carbonatite ore deposits (e.g., the Maoniuping REE deposit). Together with detailed geological features of the alkaline carbonate veins, the results obtained by the authors could provide a general guideline for exploration of carbonatite REE deposits in the East Qinling region.

    • FENG Xiao-ming, LI Zhu-cang, QI Jian-hong

      2021,40(2):347-362, DOI:

      Abstract:

      The Dewulu pluton is located between Xiahe-Hezuo fault and Lishishan-Weidangshan fault. The hose rock is predominantly composed of granodiorite with subordinate quartz diorite and quartz monzodiorite, and contains a large number of microgranular mafic enclaves (MMEs). Some Cu-Au deposits occur within the pluton and have been studied by many researchers; nevertheless, there are few researches on the pluton. LA-ICP-MS zircon U-Pb dating on the granodiorite of the Dewulu pluton yielded an age of 225.9±1.3 Ma, suggesting that the pluton was formed in the early period of late Triassic, and might have been related to the continental collision between the Yangtze and North China plates. Petrogeochemical studies show that host rocks are characterized by high K2O and low Y and MgO, while the MMEs by low K2O and high Y and MgO. Both host rocks and MMEs have similar features in trace element spider diagram and REE distribution pattern and obvious linear relationship on Al2O3/MgO-SiO2/MgO diagram. These phenomena indicate that material exchange took place in these rocks, and quartz diorite, quartz monzodiorite and granodiorite were generated by the mixing of mafic and felsic magmas resulting from the strong crust-mantle interaction occurring in the extensional environment after the collision of the Yangtze and North China plates. MMEs may be the remnant of the parental mafic magma, and their geochemical characteristics show that they might have been derived from the mantle which was enriched in Au, Cu and other ore-forming elements. The Cu and Au enriched fluid was produced during the evolution of the mixed magma, and precipitated in the Dewulu pluton to form the hydrothermal Cu-Au deposits.

    • JI Xing-zhong, CHEN Qiang, CHENG Zhi-guo, WANG Qian, MA Ke-zhong, LIU Xu

      2021,40(2):363-382, DOI:

      Abstract:

      Emeishan basalts, widely distributed in Sichuan, Yunnan and Guizhou in southwestern China, are the earliest internationally recognized large igneous provinces in China and have been favored by a large number of experts both in China and abroad. Many consensuses have been reached on the basalt in the western part of the Emeishan large igneous province (ELIP), but there are still several controversies in such aspects as the rock associations, the time limit of volcanic activities and the genesis of rocks. With the basalt of Pu'an in western Guizhou, eastern part of ELIP as the study object and through the analysis of typical basalt profiles, the authors detected that the rock types in this area are eruptive facies of volcanic breccia in the first cycle, flooding facies of basalt in the second cycle and volcanic sedimentary facies of tuff in the third cycle from bottom to top. Zircon LA-ICP-MS U-Pb dating from the tuff which is located at the top of the basalt defined the upper time limit of volcanic activity in the east of the ELIP to 250 Ma. The major and trace elements indicate that the basalts in this area are mainly high-Ti and alkaline basalts. The characteristics of Rb-Sr depletion and Ba-Hf enrichment are basically consistent with the geochemical characteristics of basalts in Guizhou, high Ti basalts in the west of ELIP, and OIB. Trace elements show that the origin of the basalt is metasomatic garnet mantle peridotite, and the melt generated by partial melting when rising from the deep mantle plume to the stable area of garnet peridotite was mixed with the continental lithospheric mantle enriched with metasomatic fluids. Crystallization differentiation was significant while the crustal mixing degree was weak during the ascent and migration of magma. The results show that the basalt in the eastern ELIP was formed in the environment of greater depth, low partial melting and high pressure at the edge of the mantle plume.

    • XU Li-juan, LI Ping, LIU Zheng, WANG Guo-chang

      2021,40(2):383-394, DOI:

      Abstract:

      Abundant Neoproterozoic magmatic rocks were emplaced in western Yangtze Block, which are important for reconstructing the Rodinia supercontinent. In this paper, new petrologic, lithogeochemical and geochronological studies of the Eshan granodiorites and porphyritic biotite monzogranites were conducted to explore their origin and geodynamic implications. The porphyritic biotite monzogranites were emplaced at 826.6±2.5 Ma, while the granodiorites have younger crystallization age of 818.3±2.8 Ma. Relative to the porphyritic biotite monzogranites, the granodiorites exhibit lower SiO2 but higher Al2O3, MgO, Fe2O3, TiO2 and P2O5 values. In chondrite-normalized REE patterns and trace element spider diagram, both lithologies are enriched in LREEs; compared with HREEs, they have negative Eu anomalies and are depleted in HFSEs relative to LILEs. The porphyritic biotite monzogranites have enriched Nd isotopic compositions, consistent with those of the granodiorites. The geochemical data indicate that the porphyritic biotite monzogranites are likely to have been derived by partial melting of meta-igneous rocks, leaving a granulite source at ca. 826 Ma and subsequent partial melting of the granulite at ca. 818 Ma, thus producing the Eshan granodiorites with A-type affinities. Combined with data available, the results obtained by the authors reveal that the western Yangtze Block was an active continental margin and the South China Block occupied an external location rather than an internal location within the Neoproterozoic Rodinia.

    • WEI Shuai, YANG Zhi, DENG Yu-feng, CHENG Pei-sheng, CHAN Si-wei, MAO Si-bin, LU Xin-zhe, YUAN Feng

      2021,40(2):395-410, DOI:

      Abstract:

      The intermediate-acid intrusions in northern Anhui Province of Xu-Su arc were formed by multi-stage magma, and a series of skarn (Fe)-Au-Cu-(Mo) and Fe-Cu deposits related to these intermediate-acid intrusive rocks have been developed. In this paper, the authors studied the zircon U-Pb age of diorite porphyrite which hosts the Wangchang skarn-type iron deposit and Re-Os isotopic age of the molybdenite in the largest skarn-type gold deposit (Yangqiaozi Au-Cu deposit) in this area. The LA-ICP-MS U-Pb weighted age of the Wangchang diorite porphyrite zircon is 132.1±1.9 Ma, and the Re-Os isochron age of the molybdenite in the Yangqiaozi deposit is 130.0±3.2 Ma. The authors systematically summarized the diagenetic age, mineralization type and metallogenic regularity in this area. It is considered that the magmatic rocks in this area can be divided into four stages, and the deposits can be divided into four types. Specifically, the first stage magmatic rocks are early Neoproterozoic mafic intrusive rocks (diabase), which are related to the diamond deposits. The second stage magmatic rocks are intermediate acid intrusive rocks formed in the early Jurassic. The third stage magmatic rocks are the Early Cretaceous intermediate-acid intrusive rocks, which are related to skarn type Fe deposits and skarn type (Fe)-Au-Cu-(Mo) deposits. The fourth stage is late Early Cretaceous acid intrusive rocks. The magmaic Cu-Ni deposits related to mafic intrusive rocks were discovered, but there has been no chronological research reported yet. The Fe and Au-Cu mineralization related to intermediate acid intrusive rocks have been widely developed, but just a few Cu-Ni and diamond mineralizations related to mafic intrusive rocks have been discovered in the in northern Anhui Province of Xu-Su arc. The magmatic rocks in the study area were formed in the extensional structural environment of the North China Craton, but were controlled by different geological events. The large-scale diagenesis and mineralization ages in the area are concentrated in the Early Cretaceous, which was probably related to the destruction of the lithosphere of the North China Craton. The chronological and geochemical data of magmatic rocks and mineralization indicate that there may be a hydrothermal gold polymetallic deposit similar to the Jiaodong area in the deep Xu-Su arc area, which provides a reference for future prospecting in this area.

    • CAO Yuan, HE Xiao-hu, TAN Shu-cheng, YANG Jian-yu, LIU Pei-ying

      2021,40(2):411-428, DOI:

      Abstract:

      The Daping Au deposit is one of the most important large-sized gold deposits in the south of the Ailao Mountain-Honghe River ductile shear zone. Due to the disputes on its mineralization timing and tectonic setting, it's difficult to establish the metallogenic model as well as further explore and exploit gold deposits in this belt. In this paper, LA-ICP-MS was used to study the U-Pb geochronology of hydrothermal zircon from Au-bearing quartz veins and magmatic zircon from diorite and granodiorite vein in the Daping Au deposit. The result shows that the age of hydrothermal zircon is 760±10 Ma, suggesting that there was a Neoproterozoic mineralization event for the Daping gold deposit. The magmatic zircons from the diorite and granodiorite vein yielded ages of 773±9 Ma and 766±9 Ma, respectively. These results coincide with the breakup of the zircons from the diorite and granodiorite veins. Therefore, combined with their consistent ages within the error range, the authors hold that the Neoproterozoic gold mineralization event might have been Rodinia supercontinent and the Jinning-Chengjiang large-scaled volcanic-magmatic event in the Ailao Mountain area. The hydrothermal zircons have similar Hf isotopic composition to those of related intrusions of diorite and granodiorite. Although the Eocene-Oligocene was thought to be a main mineralization period for the Daping gold deposit in previous literature, the authors consider that the Daping gold deposit probably resulted from superimposed mineralization from the Neoproterozoic and Cenozoic magmatic-tectonic-hydrothermal events, as shown by the determination of the Neoproterozoic mineralization event in this study.

    • YE Zi-feng, YANG Guang-shu, QIN Long-jiang, CHEN Ai-bing, WANG Kai, ZHOU Yan, MAO Zhi-bo, DAI Zhi-hui

      2021,40(2):429-451, DOI:

      Abstract:

      The Dahongshan iron-copper deposit is hosted in metavolcanic to metasedimentary rocks of the Paleoproterozoic Dahongshan Group. Up to now, the genesis and tectonic environment of these ore-bearing rocks have been still controversial, which seriously restricts the understanding of the metallogenic mechanism and process. In order to identify the original rock types and diagenetic tectonic environment of these host rocks, the authors systematically studied major, trace and rare earth element compositions of main ore-bearing metamorphic rock series, including the meta-sodic volcanic rocks, mica schists and marbles, as well as the gabbro-diabase rocks. According to the results obtained, the ore-bearing rocks are characterized by poor K, Ti and rich Na, the meta sodic volcanic rocks are relatively depleted in Ba, Sr and Ti, weakly depleted in Zr, Hf and Nb, and are enriched in Th, Nd, Sm and La; their total content of rare earth elements are generally low, with LREEs relative enrichment(LREE/HREE=1.84~9.43), significant Eu positive anomalies(δEu=0.91~3.59, mean=1.62), and no obvious Ce anomalies. These characteristics are similar to those of rocks from jet deposition or high temperature submarine volcanism in the modern mid-ocean ridge or intracontinental rift. According to the comprehensive study, the protolith of mica schist may have been a calcareous mudstone, while the protoliths of meta-sodic lavas and meta-sodic tuffs are volcanic rocks which erupted in the bathyal environment, with high Na content. Meta-sodic volcanic rocks and gabbro-diabase rocks show similar anorogenic features to the magmatic rocks in the same period of Kangdian area, indicating that they are all products of magmatic activities in the same continental rift environment which may represent the Columbia supercontinent cracking process on the western margin of Yangtze block. The continental breakup generated some channels for the migration of mantle-derived magma, and provided a good material basis for the formation of the iron copper polymetallic metallogenic belt in Kangdian area.

    • ZHANG Chuan-yu, CAO Xiao-min, LI Wen-chang, TANG Zhong, YU Hai-jun, CHEN Cao-jun, CHENG Yong, LI Rong

      2021,40(2):452-464, DOI:

      Abstract:

      The main types of beryllium deposits in Yunnan Province include pegmatite type, magmatic-hydrothermal vein type, altered granite type and greisen type. The pegmatite type, magmatic-hydrothermal vein type and altered granite type are the most important types of deposits, which account for more than 95% of the total resources of beryllium in Yunnan Province. These deposits are closely related to the high-differentiation granite of crust source and mostly distributed in Gejiu and Dulong regions in southeast Yunnan as well as in Gaoligong Mountain and Shangri-la regions in western Yunnan. The deposits were formed in the late Cretaceous in southeast Yunnan and Oligocene in west Yunnan. Beryllium mineralization in southeast Yunnan resulted from a response to lithospheric extension in western South China in late Yanshanian period. The geodynamic background of beryllium minerali- zation in western Yunnan seems to have been the collision orogeny between the Indian and Eurasian continents. In this paper, the authors propose three prospecting areas, namely Gongshan-Tengchong-Yingjiang, Longling and Maguan-Malipo prospective areas. In the three prospective areas, researchers should focus on finding pegmatite-type beryllium deposits.

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    Volume 40,2021 Issue 2
      专题研究
    • ZHANG Li-cheng, WANG Yi-tian, CHEN Xue-feng, MA Shi-qing, WANG Zhi-hua, YU Chang-fa

      2013,32(4):431-449, DOI:

      Abstract:

      The Hongyuntan iron deposit is hosted in pyroclastic rocks of the Lower Carboniferous Yamansu Formation. The ore bodies occur as layers, stratoid bodies or lenses. The principal ore mineral is magnetite, together with minor maghemite, specularite, pyrite and trace chalcopyrite. The gangue minerals include garnet, diopside, actinolite, chlorite, tremolite, epidote, biotite, albite and quartz. The ore structures are mainly of massive and disseminated forms, with occasional banded or veined forms. The ore textures are of subhedral-anhedral granular and metasomatic types. The wall rock alteration shows symmetrical zoning, and the alteration colors change from dark to light from ore bodies outwards. On the basis of observed mineral assemblages and ore fabrics, two periods of ore deposition were recognized, i.e., skarn period and hydrothermal ore-forming period, which could be further subdivided into four metallogenic stages, namely skarn stage, retrograde alteration stage (main ore-forming stage), early hydrothermal stage and quartz-sulfide stage. Electron microprobe analyses show that the end member of garnet is mainly andradite-grossularite. The composition of pyroxene is mainly diopside-asteroite. The amphiboles is composed mainly of actinolite and tremolite with minor magnesiohornblende. The composition of these skarn minerals suggests that skarn in the Hongyuntan iron deposit is calcic skarn, belonging to metasomatic skarn. The characteristics of main and trace elements suggest that the formation of magnetite was closely related to the skarn. In combination with geological characteristics, the authors suggest that the skarn might have resulted from interaction between Ca-rich pyroclastic and Fe-rich magmatic hydrothermal fluid which was transported along the fault system. The formation of magnetite was hence related to the regressive metamorphism of the skarn.

    • Gan Guoliang Yichang Institute of Geology, Mineral Resources, Chinese Academy of Geological Sciences Department of Grologicol, Atmospheric Sciences, lows State Univeraity, Ames, IAS0011, U.S.A

      1993,12(2):144-181, DOI:

      Abstract:

      This paper presents partition coefficients of 69 chemical elements (Li, Rb,Cs, K, Na, Ca, Ba, Sr, Mn, Fe, Mg, Cu, Pb, Zn, Co, Ni, Be, La, Ce, Nd,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, Cr, In, Ga, Al, B,Cd, Sb, Bi, U, Th, Zr, Hf, Si, Ti, Ge, Sn, Mo, Nb, Ta, W, V, P, F, Cl,S, N, O, C, As, Pu, Re, Os, He, Ne, Ar, Kr and Xe) and the univalent radical (OH) in 28 minerals (olivine, clinopyroxene, orthopyroxene, amphibole,biotite, Phlogopite, plagiocla-se, K--feldspar, quartz, magnetite, ilmenite, garnet,zircon, apatite, allanite, topaz, sphene, cordierite, hauyne, leucite, nepheline,whit-lockite, brookite, petovskite, melilite, armalcolite, spinel and rutile) from 8 types of rocks, namely metaluminous (ultra) basic rock, peralkaline (ultra) basic rock, metaluminous intermediate rock, peralkaline intermediate rock,metaluminous acid rock, peralkaline acid rock, peraluminous acid rock and ultra-acid rock. It is found through an integrated ahalysis and comparison that the composition and structure of minnerals and melts seem to be the most important factors controlling mineral-melt element partitioning. Importanceshould be attached to minral structure and Al-supersaturation of melt which have, not been discussed by research workers. Finally, the present state and theproblems to be solved in the study of mineral--melt element partition coefficients are analysed, and the future trends of this research field are predibted.

    • 专题研究
    • HE Shi-ping, WANG Hong-liang, XU Xue-yi, ZHANG Hong-fei, REN Guang-ming

      2007,26(4):295-309, DOI:

      Abstract:

      Early Paleozoic volcanic rocks in Tianshui and Baoji areas along the eastern segment of North Qilian orogenic belt consists of Hongtubu basaltic lavas and Chenjiahe intermediate-acid volcanic rocks. Geochemical analyses show that Hongtubu basaltic lavas are similar to the intercalated basalts in Chenjiahe intermediate-acid volcanic rocks in characteristics, both fallen in the tholeiite series with high TiO2 (1.50%~2.73%). Their∑REE are 65.97×10-6~133.46×10-6 and 78.04×10-6~175.55×10-6 respectively, both are slightly enriched in LREE [(La/YbN being 2.00~4.40 and 2.71~4.40 respectively],and both have no obvious Eu anomaly or weak Eu negative anomaly(δEu being 0.85~1.10 and 0.85~0.99 respectively). Basalts from two groups are typically characterized by selected enrichment of LILEs, low abundances of HFSEs relative to NMORB, and prominent troughs of Nb and Ta, with low Nb/La ratio(0.28~0.43), which indicates the affinity of these volcanic rocks to island arc tholeiite(IAT). In addition, εNd(t)(+2.22~+4.08)values of basalts suggest that their mantle sources are similar to the depleted mantle source. Zr/Nb=17.21~36.33 and Ce/Nb=5.73~8.17, implying geochemical characteristics of N-MORB. Sr, Nd and Pb isotopes from Hongtubu basalts are similar to those in Chenjiahe basalts in composition. In the diagrams of εNd(t)-(87Sr/86Sr)t, (207Pb/204Pb)t-(206Pb/204Pb)t,(87Sr/86Sr)t-(206Pb/204Pb)t and εNd(t)-(206Pb/204Pb)t for basalts, the data are fallen in the DM, EMⅠand EMⅡ areas, probably with a little crustalontamination, indicating that the magma of basalts might have had a mixed gin.Thentermediate-acid volcanic rocks from Chenjiahe belong to the calc-alkaline series,they have relatively high abundances of REE∑REE=127.51×10-6~276.01×10-6), and are significantly enriched in LREE[(La/YbN= 4.79~13.51]. Most intermediate-acid volcanic rocks show weak Eu negative anomaly (δEu=0.53~1.20). The trace element patterns of Chenjiahe acid volcanic rocks are similar to those of the ocean ridge granite (ORG), with marked troughs of Nb, Ta, Zr and Hf. A synthetic study shows that the Chenjiahe intermediate-acid volcanic rocks in the eastern segment of North Qilian orogenic belt were formed in an island-arc setting, whereas the Hongtubu basalts were formed in an intra-arc rift setting (or an initial back-arc basin setting), probably being products of the early spreading evolution of the island_arc system towards the back-arc basin in the eastern segment of North Qilian during late Early Paleozoic. The results obtained provide evidence for the existence of the trench-arc-basin system at the juncture of Qilian and North Qinling orogenic belts.

    • 宝玉石矿物学
    • YAN Ruogu, QIU Zhili, DONG Chuanwan, LI Liufen

      2009,28(3):292-298, DOI:

      Abstract:

      High grade black jadeite is a kind of upscale and fashionable jade material that has become one of the jadeites characterized by fastest growing values in the past 20 years. Based on a comparison of mineralogical and geochemical characteristics between black jadeites (inky black jades)from different producing areas of the world, the authors hold that the black jadeites currently on the market can be mainly classified into jadeite jade, omphacitic jadeite jade and hornblende jade whose main components are jadeite, omphacite and dark green hornblende respectively. They include black chicken jade, ink jadeite and black kosmochlor from Myanmar and jade negro and galactic gold from Guatemala, with black chicken jades similar to those from Myanmar also seen in Japan and Kazakhstan. The research results suggest that the main mineral composition, jade structure and inclusion characteristic combinations of black jadeite jades from different producing areas have their respective typomorphic natures, which can be used as the distinctive characteristics for their sources.

    • 综合资料
    • SHEN Qi-han

      2009,28(5):495-500, DOI:

      Abstract:

      This paper has mainly recommended a mineral abbreviation list (see Table 2 and Table 3). Table 2, which contains 243 minerals, was compiled by IUGS Subcommittee on the Systematic of Metamorphic Rocks (SCMR) in 2007. The author selected other 29 minerals and, on such a basis, formulated Table 3. Thus, the total mineral abbreviations come to 272. It is hoped that they can be popularized in future and become more and more perfect through utilization, so as to provide a basis for ultimate standardization and unification.

    • 综述与进展
    • ZHANG Wei

      2014,33(4):747-762, DOI:

      Abstract:

      Cordierite is a mineral material characterized by low thermal expansion coefficient and good thermal shock resistance. Cordierite mineral material is relatively rare in nature, so cordierite is synthesized usually by the method of artificial synthesis. Based on the newest investigation results of synthetic cordierite, this paper deals with the progress of researches on such synthesis methods of cordierite as high purity oxide solid reaction at high temperature, natural mineral solid reaction at high temperature, the utilization of industrial wasted materials, the employment of agricultural wasted materials, the sol-gel and the low-temperature combustion synthesis. At present, the method of natural mineral solid reaction at high temperature is used for the preparation of cordierite in industry. In spite of a lot of advantages, this method also has many disadvantages. Therefore, the development trend of cordierite synthesis seems to solve the problem as to how to apply other synthesis methods to industrial preparation.

    • 专题研究
    • CAO Guang-yue, XUE Huai-min, WANG Jin-guang

      2014,33(6):1019-1038, DOI:

      Abstract:

      In this paper,LA-ICP-MS zircon U-Pb dating was carried out for four samples of volcanic rocks from Qingshan Group in Jiaodong area and, as a result, their concordant ages were obtained, which are 119.4±0.9 Ma, 118.2±1.0 Ma,120.2±0.9 Ma and 120.0±0.8 Ma, respectively. The results show that all the volcanic rocks in Jiaodong area were formed from about 120 Ma to 118 Ma in the Early Cretaceous period. The ages of Qingshan Group volcanic rocks from Shandong Province controlled by Tan-Lu fault are similar to those from the Su-Wan segment of the Tan-Lu fault zone,but younger than those around the Tan-Lu fault zone,which indicates that the duration of volcanic eruption along Tan-Lu fault is probably longer than the duration in other areas under the background of lithospheric thinning in eastern China. Geochemically, all the intermediate and acidic volcanic rocks have high K2O, ALK, LREE values and low MgO, TiO2, Ni, Cr, HREE values. According to the geochemical features, the volcanic rocks can be subdivided into trachyte-trachydacite and rhyolite. The trachyte-trachydacite is characterized by LILE enrichment(Rb,Ba,K)and HFSE depletion(Nb,Ta,Ti,P), but the rhyolite exhibits stronger depletion of Ba,Sr and HFSE (Ti,P). Compared with the rhyolite,the trachyte-trachydacite possesses higher Sr and Ba values as well as La/Nb and Ba/Nb ratios,but lower Rb/Ba ratios and δEu values. All these data indicate that they might have been derived from different magma sources. It is inferred that the trachyte-trachydacite rocks were derived from the mixture of the partial melting of the lower crust(Yangtze Craton or North China Craton)and enriched lithospheric mantle. In addition, the rhyolites were related to the partial melting of the lower crust in the regional extension environment and high geothermal anomaly background with crystallization differentiation during the magma evolution.

    • 宝玉石矿物学
    • GUO Li-he, HAN Jing-yi, LUO Hong-yu

      2006,25(4):349-356, DOI:

      Abstract:

      At present, the infrared transmission spectroscopy is the best technique for determining whether jadeite is polymer-impregnated or not, and the infrared reflectance spectroscopy is a nondestructive and rapid determination method that provides mainly the fundamental frequency vibration spectra data of minerals and shows new application potentials in gemological research, especially in the identification of gem species. The gemological application of IR reflectance spectroscopy and the identification system of IR spectra of gems, including a database of 318 spectra and a searching and identifying program, are described in this paper.

    • 专题研究
    • LIN Guang-chun

      2013,32(4):485-495, DOI:

      Abstract:

      Petrology, geochemical and Nd isotopic data are reported for the Neoproterozoic Danba metabasalt in the Kangdian Rift on the western margin of the Yangtze block. Samples were collected from alkaline basalts, which are enriched in MgO, TiO2, with Mg# being 0.51~0.59. They have high total rare earth elements and show high fractionation between LREE and HREE. The trace elements are characterized obviously by enrichment of Th, Nb, Ta, Zr, Hf and LREE but depletion of Y and HREE. Their geochemical and Nd isotopic characteristics suggest that they are similar to OIB. The basaltic magma was generated in an intraplate setting, and was generated by partial melting of OIB mantle source region, with variable degrees of contamination of SCLM during magma ascending; in addition, some samples might have experienced contamination of the lower crust. These samples reveal some plume magmatism characteristics in petrochemistry, and imply that magmatism was probably related to the Neoproterozoic plume event, which resulted in the breakup of Rodinia supercontinent.

    • ZHANG Kan, ZHU Xiang-kun

      2013,32(4):529-537, DOI:

      Abstract:

      The newly-exposed lower strata of the Xiamaling Formation near Tielingzi Village in Jixian County contain rich siderites. This paper reports the basic geological characteristics of these siderite-rich strata in terms of the field outcrop, petrology and major elements. Studies show that the profile is characterized by black shale interbedded with silty iron-rich layers/siderite concrete layers, and also has minor siltstone. Some iron-rich strata have turned into limonite layers in the outcrop because of intense weathering. Siderite is the main iron mineral phase in the strata. Siderites can form iron concretes, showing micritic or microcrystalline granulitic textures under the microscope, or form silty ferruginous layers with almost a comparable amount of silty quartz; it can also distributed sporadically in siltstone and black shale with relatively coarse particles. There also exists very little siderite residue in weathered limonite layers. The overall features of major elements show that the strata are rich in SiO2, TFe and TOC, but poor in MnO, CaO, MgO, P2O5 and S. Except for ferriciron in weathered layers, there is mainly ferrous iron in the strata. The TOC content decreases in order of siderite concrete, silty iron-rich layer, black shale and siltstone. The correlation diagram between TFe and Al2O3 content shows a negative correlation in iron-rich layers, while a positive correlation between them exists in normal black shale and siltstone, which suggests that iron in the former form originated from the ocean itself, while iron in the latter form originated mainly from terrigenous detritus. In addition, FeO content has a positive correlation with TOC content in fresh samples, which implies that the genesis of siderites may have some relationship with organic matter.

    • Zhou Zheng

      1997,16(1):81-90, DOI:

      Abstract:

      From the discovery of the first new mineral hsianghualite in 1958 to the end of 1995,74 new minerals found in China had been approved by IMA CNMMN. Among them, 2/3 were discovered after 1981. The discovery of new minerals in China has the following features:(1) With the development of analytical methods, the number of new minerals discovered per year increases gradually: from the end of 1950s to 1960s, only one new mineral was discovered every year on the average, whereas from 1980s till now, three new minerals were discovered averagely every year. (2) The structures of many new minerals have been determined. (3) Most of the new minerals are in the lower category, mainly in the monoclinic system, and perfect crystals are rare; hsianghualite has the most abundant crystal faces, whose ideal faces can reach 146. (4) Among those new minerals, silicates take the first place in number, followed by native elements, alloys, and then oxides. (5) The modes of occurrence of new minerals are varied, most of them occurring in oxidized zones of various deposits and deposits related to ma fic or ultramafic rock masses. There are a few new minerals occurring in skarn and placer deposits or even in cosmic dusts and meteorite.(6) The new minerals are characterized by wide but uneven distribution. Till now, new minerals have been discovered in 20 provinces or autonomous regions, especially in Hebei, Qinghai, Inner Mongolia and Henan. The number of new minerals found in North China is larger than that found in South Chine. (7) The number of discoverers of new minerals is in tens. The first discoverer of new mineral is Prof. Huang Yunhui, whereas Prof. Yu Zuxiang is the one who discovered the most numerous new minerals in China, totally disclosing 11 new minerals by himself or together with other experts. Most of the discoverers are members of the Chinese Academy of Geological Sciences, China University of Geosciences, and Institute of Geochemistry, Academia Sinica as well as other educational and scientific research institutions. The discovery of new minerals has promoted the development of mineralogy in China. Tens of discoverers were awardees of the National Natural Sciences Prize or the Science and Technology Progress Prize of the Ministry of Geology and Mineral Resources for the discovery and research results of new minerals in 1980s. More than 60 new mineals discovered in China were collected by the Geological Museum of China, with some of them exhibited in the Minerals and Rocks Exhibiting Room.

    • 其他
    • LUO Yue-ping, DENG Wang-hui, DUAN Ti-yu, WANG Chun-sheng

      2011,30(Z1):181-186, DOI:

      Abstract:

      As more and more treated turquoises appear on Chinese gem market, the authors collected lots of turquoises from different deposits on Chinese gem market in order to sum up the characteristics of the natural turquoises on Chinese gem market. At the same time, different types of treated turquoises were studied to find general difference between them and natural turquoises. The results show that natural turquoise and treated turquoise have different shades of color, inclusions and appearances. IR spectra of both natural and treated turquoises were studied, indicating that there are absorption peaks at 1 735, 1 600 and 1?500 cm-1 in treated turquoises, which are caused by the man-made polymer. If the turquoise is treated by polymer, there are absorption peaks at 1 735, 1 600 and1 500 cm-1 in a turquoise, and this can serve as convincing evidence in this aspect.

    • 专题研究
    • ZHU Xin-you, WANG Yan-li, CHENG Xi-yin, TIAN Ye

      2016,35(1):16-32, DOI:

      Abstract:

      There are several types of xenoliths, such as monzonite, quartz diorite porphyry, black rock and greisen schlieren, in the alkali feldspar granite of the Yaogangxian tungsten deposit, Hunan Province. The xenoliths are different in geological and geochemical characteristics, sources and evolution paths, which implies the genesis and magma evolution history of the Yaogangxian granite. In this paper, the authors studied the petrology, geochemistry of the xenoliths, alkali feldspar granite, and monzonite batholiths formed in late Jurassic period. It is detected that the monzonite inclusion (Ⅰb) came from early crystallization of deep magma chamber similar to the monzonite batholith. The quartz diorite porphyry and black rock xenoliths seem to have been the residue of Precambrian metamorphic rocks in the melting. The greisen schlieren resulted from the transition from the alkali feldspar granite stage to the magma-hydrothermal stage. The fine biotite granite xenolith (Ⅲb) in the quartz porphyry was captured from the supplementary granite which was differentiated from the main magma, or from the granite pluton formed from the supplementary rocks. The granite (Ⅰ) was rich in volatiles, which resulted in strong contamination of the xenoliths, and a certain amount of fluorite, mica, tourmaline and sulfide minerals formed in the xenoliths. The Yaogangxian granite is a product of the intrusion of highly fractionated magma derived from the magma chamber equivalent to monzonite batholith. The quartz porphyry magma directly resulted from the residue of segregation from fractional crystallization of magma chamber, rather than from the alkali feldspar granite of Yaogangxian. It is suggested that the magma evolved in order of magma chamber (main) (coarse monzonite) → fine biotite granite (supplementary) → alkali feldspar granite → magma-hydrothermal transition fluid (tungsten mineralization) → quartz porphyry veins.

    • LI Yu-long, YANG Zhu-sen, TIAN Shi-hong, ZHAO Zhi-yi, LU Shi-yin, ZHANG Yao, LIU Ying-chao

      2015,34(5):648-664, DOI:

      Abstract:

      Two kinds of carbonate hosted Pb-Zn deposits, namely carbonate-rich Pb-Zn deposits and fluorite-rich Pb-Zn deposits, extensively exist in the same Pb-Zn metallogenic belt in the world according to the classification based on gangue mineral assemblages. The relationship between the two kinds of deposits remains unclear. In the middle part of the 'Sanjiang' metallogenic belt in the Tibetan Plateau, the Dongmozhazhua carbonate-rich Pb-Zn deposit and the Mohailaheng fluorite-rich Pb-Zn deposit occur in the same carbonate-hosted Pb-Zn ore concentration area. In the two deposits, the carbonate strata are host rocks, the thrust faults are the main ore-controlling structures, the main orebody attitudes are of stratabound type, and sphalerite and galena are the main ore minerals. However, calcite and dolomite are the main gangue minerals in the Dongmozhazhua deposit while calcite and fluorite are the main gangue minerals in the Mohailaheng deposit. The geochemical features of rare earth elements (REE) in calcium-bearing minerals are different in the two deposits. The REE values of calcite in the Dongmozhazhua deposit are mainly characterized by obvious fractionation of LREE and HREE, enrichment of LREE, negative Eu anomalies and 'V'_shaped curves of chondrite-normalized REE patterns with right deviation. In contrast, the REE values of calcite and fluorite in the Mohailaheng deposit are chiefly characterized by no obvious fractionation between LREE and HREE, negative Eu anomalies and 'M'_shaped curves of chondrite-normalized REE patterns with right deviation. The total concentrations of REE (∑REE) of calcite (0.46×10-6~10.79×10-6) in the Dongmozhazhua deposit are higher than those in the Mohailaheng deposit (0.25×10-6~5.88×10-6). The geochemistry of the REE indicates that calcium-bearing minerals in the two deposits were all precipitated from a kind of hydrothermal fluids which had nothing to do with igneous activities. The salinity and reducibility of the fluids decreased with the sulfide precipitation. The two kinds of deposits had similar hydrothermal fluids; nevertheless, there existed another kind of fluid for the Mohailaheng deposit, which was a kind of fluorine-rich fluid from deep metamorphic basement. This fluorine-rich fluid controlled the location of the fluorite-rich carbonate hosted Pb-Zn deposits and could be used to explain the phenomenon why this kind of Pb-Zn deposits were more easily precipitated near the main thrust faults and the lowest carbonate strata in the region. The result achieved by the authors could answer the question why the carbonate-rich Pb-Zn deposit and the fluorite-rich Pb-Zn deposit can occur in the same region and same time in the world.

    • ZHANG Wen, WU Tai_ran, HE Yuan_kai, FENG Ji_cheng, ZHENG Rong_guo

      2010,29(6):719-731, DOI:

      Abstract:

      Beishan area is located in the west of Inner Mongolia and Gansu Province, which is the conjunction zone of Tarim plate, Sino-Korea plate and Kazakhstan plate and plays an important role in the study of the Central Asia Orogenic Belt (CAOB). The relationship of the three plates is so complicated that there exists much controversy concerning Paleozoic tectonic evolution in this area. Granitoids, especially Late Paleozoic granitoids, are widely distributed in Beishan area, which are of great importance in the study of Paleozoic magmatic evolution. Through analyzing the spatial and temporal distribution of the Late Paleozoic granitoids, we can find the relationships between these granitoids and explore the crust-mantle interaction in Beishan area during Late Paleozoic, which is important for determining the geotectonic evolution of this area. In the southern belt of Beishan, the most important tectonic event in Permian is the formation of Yin'aoxia rift zone, which makes the study of Late Paleozoic evolution more complex. The results of studying Xijianquanzi granite lying in the southern belt of Beishan in such aspects as major elements, trace elements, REE and LA-ICP-MS zircon U-Pb geochronology have provided new evidence for regional tectonics. The LA-ICP-MS zircon U-Pb age of Xijianquanzi granite is 266.1±2.2 Ma, and the Hf modal ages are 746~871 Ma. εHf(t) values are +1.3~+4.7 with an averageof +2.7, which implies the mixture of crustal and mantle.derived magmas. This feature coincides with that of other areas in the Central Asia Orogenic Belt (CAOB). Therefore, the granites in the belt may have similar magma sources. The granitic body mainly consists of monzonitic granites which belong to alkaline series with high content of SiO2 (74.33%~76.67%), Na2O+K2O (9.26%~9.57%, NK/A=0.9~1.08) and K2O (Na2O/K2O<1) . In addition, chondrite-normalized REE patterns and primitive mantle normalized geochemical patterns of all samples are approximately parallel to each other, which shows that they evolved from the same magma source. Chondrite-normalized REE patterns of the intrusive body are of “V" types and show enrichment of light rare earth elements (LREE) with low ratio of (La/Yb) N (3.18~5.29) and negative Eu anomalies (δEu =0.10~0.16). Except for Eu, the abundance of rare earth elements are demonstrably over 10 times that of chondrite. Depletion of Nb, Ba, Sr, Ti, P and enrichment of Rb, Th, K can be seen in the spidergram. Based on regional geological and geochemical characteristics, the authors have reached the conclusion that the Xijianquanzi intrusive body is an alkali-rich potassium-high granite which is a mixed product of crustal and mantle-derived magmas and was formed at the stage of rifting in the post-collisional extensional period, affected greatly by Yin'aoxia rift zone. This implies that the area entered into the stage of rifting in Middle Permian.

    • 综合资料
    • ZHANG Xi-huan, REN Yu-feng

      2008,27(2):135-151, DOI:

      Abstract:

      本文以表格的形式列举了经国际矿物学协会(IMA)新矿物与矿物命名委员会(CNMMN)批准、并于2003年度正式发表的新矿物共55种,其中硅酸盐31种,磷酸盐5种,砷酸盐2种,硫酸盐4种,硫化物3种,碳酸盐2种,钒酸盐2种,硼酸盐1种,硒化物1种,硫盐1种,氧化物1种,氢氧化物1种,复杂卤化物1种.文中表格依次列出了矿物的中外文名称及化学式、晶系及晶胞参数、主要粉晶数据、物理性质、光学性质、产状及共生(伴生)组合等.

    • 中国大陆环境典型斑岩型矿床成矿规律和找矿模型:研究进展(Ⅱ)专辑
    • ZHOU Jin-sheng, JI Xian-hua, YANG Zhu-sen, HOU Zeng-qian, ZHUANG Liang-liang

      2015,34(4):557-567, DOI:

      Abstract:

      In the magma-related deposits, the ore-forming plutons generally experienced high-degree evolution and differentiation, so its petrologic and geochemical characteristics can only reflect the final state of magma evolution. The evolution of ore-hosted magma and the geochemical behavior of main metallogenic elements in the evolution remain unclear. However, the study of contemporaneous and sympatric magmatic rocks provides a potential solution for this question. Here the authors made a case study of the northern Gangdise Pb-Zn ore belt in Tibet formed in the early period of continental collision. Based on the statistical study of lots of published geochemical analyses of magmatic rocks from the Gangdise belt, this paper presents the evolution of magma and its control of metallogenesis. The results suggest that, besides the crystallization differentiation of magma itself, crustal contamination was another factor controlling the evolution from basic magma to acid magma during differentiation. It is also found that most of the magmatic rocks formed in the early period of continental collision are less oxidized and less hydrous; nevertheless, when magma evolved to the middle and late period, the oxidation of magma increased with progressive evolution. Mantle-derived magmas are enriched in S and H2O, which experienced underplating at the base of Zn-enriched crust materials and induced partial melting. Crust-derived magmas experienced high-degree evolution, and finally resulted in the formation of the northern Gangdise Pb-Zn ore belt.

    • 综合资料
    • AI Yu-jie, FAN Guang

      2015,34(1):117-128, DOI:

      Abstract:

      This paper presents a collection of 31 new uranium minerals approved by the Commission on New Minerals, Nomenclature and Classification (CNMMN) of the International Mineralogical Association (IMA) between January 2003 and December 2013. It lists the mineral names both in English and Chinese together with their structural formulae, crystal structure data, physical and optical properties, localities and modes of occurrence. The crystallochemical classification and characteristics of these new minerals are discussed. Some suggestions are put forward concerning China's uranium minerals research work in the hope of providing valuable reference for China's uranium researchers.

    • 专题研究
    • SHI Jian-rong, LIU Fu-lai, LIU Ping-hua, MENG En, LIU Chao-hui, YANG Hong, WANG Fang, CAI Jia

      2014,33(1):29-50, DOI:

      Abstract:

      Eclogites and blueschists are exposed mainly as slices or variable tectonic lenses within garnet phengite schists in Habutengsu area, southwestern Tianshan Mountains, Xinjiang. In this paper, petrography, mineralogical chemistry and p-T conditions of the eclogites and blueschists were studied in detail. The eclogites could be divided into four groups, i.e., glaucophane eclogites, paragonite eclogites, epidote eclogites, and glaucophane-garnet amphibolites (retrograde eclogites), whereas blueschists could be divided into three groups, namely glaucophane-bearing garnet-muscovite-albite schists, garnet-muscovite-glaucophane schists and garnet-muscovite-glaucophane-quartz schists. Major mineral assemblages are Grt+Omp+Pg+Ep for the fresh eclogites, Grt+Gln+Amp for the retrograde eclogites, and Grt+Gln+Phe+Pg+Ab+Qtz for the blueschists. Porphyroblastic garnets show perfect prograde zoning, with XMn and XFe deceasing and XMg and XCa increasing from the core to the rim, which indicates a process of increasing temperature and prograde metamorphism. According to the paragenetic assemblages of inclusions within garnet as well as in matrix, four stages of metamorphism were recognized, viz., pre-peak lawsonite-blueschist facies metamorphic stage, peak eclogite facies stage (t=543~579℃, p=1.5~1.6 GPa), retrograde epidote-blueschist facies stage (t=~450℃, p<1.0 GPa), and post-peak retrograde blueschist-greenschist facies stage (t<400℃, p<0.5 GPa). The p-T pseudosection calculation shows that the peak metamorphic conditions were 520~550℃ and 1.7~1.9 GPa for the eclogites, and 520~620℃ and 1.7~2.3 GPa for the blueschists, similar to the results of traditional geothermobarometer. Previous researchers reported coesites preserved in some eclogites and country rocks, which suggested that partial eclogites and partial country rocks within the southwestern Tianshan metamorphic belt underwent UHP metamorphism, but this conclusion is inconsistent with the results constrained by the eclogites in this study. The possible reasons might be as follows: ① the eclogites were affected by later thermal events, which led to the partial variation of both minerals and whole rock compositions. On the basis of the changed whole-rock compositions, the traditional thermobarometer Grt-Cpx-Phe and phase equilibrium simulations certainly show relatively low pressure results, and ② not all eclogites from the southwestern Tianshan underwent UHP metamorphism, and HP-UHP eclogites may represent the metabasites subducted to different depths.

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    Editor:Zengqian Hou

    Started in:1982

    ISSN 1000-6524

    CN 11-1966/P