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2019yearNo.38volumeNo.10phase

  • The discovery of eclogite-high-pressure granulite association from Hainan Island, South China
    XIA Mengmeng, HU Juan, HU Daogong and LIU Xiaochun
    An eclogite-high-pressure (HP) granulite association were firstly discovered in the Mulantou area, northeastern Hainan Island, South China. The HP rocks occur in the coastal intertidal zone, and consist mainly of garnet, omphacite, hornblende, quartz and rutile, with or without zoisite or plagioclase. Peak p-t conditions of the rocks obtained by conventional geothermobarometers are about 800~850° C and >1.5GPa. U-Pb zircon dating yields metamorphic ages of about 340~300Ma. The occurrence of HP granulite-eclogite association is of great significance for understanding the tectonic affinity of Hainan Island and the tectonic evolution of the eastern Paleo-Tethys.
    2019  .  38(10):    1591-1594    [摘要](18)    [PDF](17)
  • A study of tectonic style of the polymetallic ore concentration area in Southern Lhasa terrane——Evidence from deep seismic reflection profile
    XU Tairan, LU Zhanwu, ZHANG Xuemei, LI Wenhui and JIA Junlian
    The Niangre and Xiongcun areas in the middle section of the Gangdise metallogenic belt have gradually attracted attention due to the continuous discovery of metal deposits such as iron and copper deposits in recent years. However, due to the lack of sufficient geophysical data, the fine structure of the crust in this area has not been clearly understood, which restricts the study of the ore-forming background of this area. Employing the data of 130km deep seismic reflection profile of the Xiongcun-Niangre ore concentration area and encrypted reflection profile inside 25km of the ore concentration area, the authors carried out data processing of tomographic static correction, denoising, energy compensation and velocity analysis, and obtained the reflection image crustal structure of the Xiongcun-Niangre ore concentration area. Based on the geological data of this area, the authors explained and inferred the deep structure of the ore concentration area, revealed multiple faults in the upper crust and various geological phenomena. It is determined that the fault is related to the direction of the magma flow. The results have certain value for the study of the oreforming background of the ore concentration area.
    2019  .  38(10):    1595-1602    [摘要](10)    [PDF](9)
  • The discovery of the sporopollen fossils from the Middle Jurassic Yangye Formation in Qiemo area of Xinjiang and its geological significance
    ZHAO Zhigang, ZHANG Xionghua, LI Xiaoyang, SUN Zhijia, ZENG Jiao and WANG Yunliang
    Abundant sporopollen fossils, which include 37 genera and 81 species, were found for the first time in the Yangye Formation in Jiangalsay, Qiemo, Xinjiang. According to the characteristics and stratigraphic distribution of sporopollen fossils, the age of the Cyathidites-Neoraistrickia-Disacciatrileti belongs to the early stage of Middle Jurassic. The palynological assemblage is well correspondent to that of some regions in Northwest China and North China. By studying the kinship between the sporopollen components and vegetation types, the authors have reached the conclusion that the vegetation at the early stage of Middle Jurassic was mainly composed of Filicinae, lycopods conifers and cycad in Jiangalsay, which suggests that the paleclimate belonged to the tropicalsubtropical humid climate.
    2019  .  38(10):    1603-1614    [摘要](9)    [PDF](10)
  • The tectonic evolution of the Garze-Litang ophiolite mélange zone in the Late Triassic: Constraints from geochronology and geochemistry of the Yongjie batholith in the Garze-Litang area
    QIN Meng, YAN Songtao, WEN Lang, TAN Changhai and DUAN Yanghai
    The Garze-Litang ophiolite mélange zone is an important part of the ‘Three-River’ orogenic belt in Southwest China, which experienced the evolution of paleo-Tethys and formed a complete trench-arc-basin system. The Yidun arc belongs to "the Garze-Litang arc basin system", located on the west side of the Garze-Litang suture zone. Petrological, geochemical and geochronological studies of the Yongjie batholith in the Yidun arc have provided new evidence for tectonic evolution of the GarzeLitang Ocean basin in the Late Triassic. The zircon U-Pb ages of the biotite adamellite and the granitic aplite are 214.2±1.4Ma and 206.2±1.8Ma, suggesting high-K calc-alkaline metaluminous to peraluminous rocks, with REE patterns displaying enriched LREE, flat HREE and obvious negative Eu anomaly, and trace elements showing relative enrichment of large iron lithophile elements Rb, Ba, Th, U and K and depletion of high field strength elements Nb, Ta, P and Ti. Geochemical characteristics show that the biotite adamellite of the Yongjie batholith has the obvious features of subducting granite, and the granitic aplite has the characteristics of collision granite. All these features suggest that the Garze-Litang Ocean basin had the geodynamic setting from subduction to collision in the late Triassic, and it should be the product of the collisional orogeny in the Garze-Litang ophiolite melange belt.
    2019  .  38(10):    1615-1625    [摘要](10)    [PDF](13)
  • Paleozoic magma evolution at the eastern end of Northern Qilian orogenic belt: Evidence from the zircon U-Pb ages, trace elements and Hf isotopic composition of Changgouhe dioritic gneiss
    ZHANG Jiayao, HE Yanhong, CHEN Liang and XU Kexin
    Outcropped at the eastern end of the Northern Qilian orogenic belt in Tianshui area of Gansu Province, Changgouhe dioritic intrusion has traditionally been considered as Precambrian intrusive rocks due to their gneiss structure. The results of LAICP-MS zircon U-Pb dating in this study show two groups of magmatic zircon crystallization ages at 463.3±2.3Ma (MSWD=0.52, n=11) and 443.8 ±2.6Ma (MSWD=0.44, n=9). Zircon trace element analyses show that these two groups share the similar trace element compositions, indicating that they crystallized in a closed magmatic system. t-Eu/Eu* diagram shows that the magmatic zircons of about 460Ma have no Eu anomalies, similar to the REE patterns of mantle-derived zircons. The negative Eu anomaly of about 440Ma magmatic zircons indicates that the parent magma began to crystallize plagioclase, consistent with the process of the anatexis. Therefore, about 460Ma is the formation age of Changgouhe dioritic gneiss, and about 440Ma is the crystallization age of anatexis magma of Changgouhe dioritic gneiss. Hf isotope analysis shows that εHf(t) values of about 460Ma and about 440Ma zircons are 8.23~11.57 and 6.36~8.03 respectively, indicating that mantle-derived juvenile crustal magma was developed at about 460Ma and that more involvement of crustal remelting took place at about 440Ma.
    2019  .  38(10):    1626-1636    [摘要](6)    [PDF](10)
  • LA-ICP-MS zircon U-Pb age of Late Carboniferous quartz diorite in Yiwu area of Xinjiang and its geological significance
    MA Junqiang, YANG Jun, ZHANG Kai, PAN Yanghui, CHENG Bolin and YANG Xiaojun
    The Late Carboniferous intrusions in Yiwu region of Xinjiang were produced in the eastern section of TianshanXingmeng orogenic belt. LA-ICP-MS technological analysis shows that the quartz diorite zircon 206Pb/238U age of the study area is 312.4±1.5Ma (MSWD=0.18, n=30), suggesting Late Carboniferous epoch. The petrochemical data show that the late Carboniferous intrusive rocks in Yiwu region belong to aluminum alkaline rock series characterized by LREE enrichment and HREE flat type, with moderate Eu negative anomaly. Trace elements in rocks are characterized by enrichment of light rare earth elements and large ion lithophile elements such as Ba and Th, and the relative loss of Nb, Ti and P; strong P element loss may be associated with apatite crystallization separation. These elements and the continental crust material have an obvious affinity. These data reveal that the Yiwu region was in a post-collision tectonic environment in the Late Carboniferous.
    2019  .  38(10):    1637-1646    [摘要](14)    [PDF](18)
  • Sedimentary environment, formation age and significance of the Middle Permian Zhesi Formation in Zhuolunyinnuoer, Sonid Left Banner, Inner Mongolia
    ZHAI Peng, XU Bei, WANG Zhiwei, TIAN Yingjie, ZHANG Yanjie and YAO Zhongwei
    The Zhesi Formation can be divided into siltstone-shale member in the lower part and conglomerate-sandstone member in the upper part in Zhuolunyinnoer, southern Sonid Left Banner, Inner Mongolia, representing overbank deposition of middle fan subfacies and proximal rapid deposition of inner fan subfacies, respectively and implying a paleogeographic framework characterized by alluvial fan in intracontinental basin with the shallow water and oxidation conditions. Geochronological research on detrital zircon reveals a complex provenance containing the Xing'an-Ailigemiao block, the early Paleozoic arc belt and late Carboniferious and early Permian plutons. The youngest detrital zircon peak age of 281Ma from the Zhesi Formation and another age of 248±3Ma from diorite porphyrite that intruded into the Zhesi Formation were obtained in the study area, which shows that the formation age of the Zhesi Formation is between the Middle Permian and Early Triassic. Regional geology analysis reveals that there existed middle to Late Permian terrigenous clastic sedimentary basins in the central and western parts of the Xing-Meng orogenic belt (XMOB). They were isolated from each other with different sedimentary sequences, suggesting "basin-and-ridge" structure style and intracontinental extensional tectonic setting during the Permian in the XMOB.
    2019  .  38(10):    1647-1659    [摘要](9)    [PDF](6)
  • Chronology, geochemical characteristics and its geological significance of Mesozoic volcanic rocks in Ganzhuyinaobao area, Abag Banner, Inner Mongolia
    YANG Duo, LI Mengmeng, GONG Quande, CHEN Tianhong, MAO Lei, QIN Tian and ZHAO Liang
    LA-ICP-MS zircon U-Pb dating results and geochemical data for the Mesozoic volcanic rocks from the Ganzhuyinaobao area of Inner Mongolia were presented in order to constrain their chronology, petrogenesis and the regional tectonic evolution. Manketouebo Formation persilicic volcanic rocks and Meiletu Formation intermediate volcanic rocks are extensively distributed in the study area. LA-ICP-MS zircon U-Pb dating results show that rocks of the two formations were formed at 163.6±0.6Ma and 139.6±0.7Ma, respectively. Geochemical researches indicate that the volcanic rocks in Manketouebo Formation are characterized by rich silica and alkali but poor TFeO, Al2O3, TiO2, MgO, CaO and Na2O, belonging to the alkaline series. The rocks with characteristics of A-type granite are enriched in LREE and LILE (Rb, Ba, Th, U and K) and depleted in HREE, some(Ba, Sr) and HFSE, especially Nb, Ta, P and Ti, with highly negative Eu anomalies, suggesting that they originated from the melting of the crust rocks. The Meiletu Formation intermediate rocks belong to the alkaline series, with enrichment of alkali, K, Al2O3, TiO2, MgO and (LILEs) Rb, Ba, Th, U, K and depletion of HREE as well as Nb, Ta, Ti, Y, Yb and Lu and weak negative Eu anomalies. They were derived from the melting of mafic iron in the lower crust. Combined with characteristics of petrology and tectonic setting of the area, it is held that Manketouebo Formation persilicic volcanic rocks and Meiletu Formation intermediate volcanic rocks occurred in an intense lithopheric extension tectonic setting that was caused by the collapse or delamination of thickening crust resulting from the subduction of Mongolo-Okhotsk heading to the west slope of Da Hinggan Mountains-northern Hebei-western Liaoning region.
    2019  .  38(10):    1660-1674    [摘要](10)    [PDF](9)
  • Geochemical, age and Hf-in-zircon isotopic characteristics and geological significance of granite and MME from the Mandelinwula pluton, northern Alxa block, Inner Mongolia
    ZHANG Jianjun, ZHANG Lei, WANG Tao and SHI Xingjun
    Early Paleozoic to Early Mesozoic intrusive rocks are widely distributed in northern Alxa region, Inner Mongolia. The temporal and spatial distribution, magma source components and petrogenesis for these rocks are important for studying the tectonic evolution of northern Alxa, and even for studying the late stage evolution of the southern Central Asian orogenic belt. Mandelinwula pluton, located in the west part of the Yabulai-Nuoergong-Honggueryulin tectonic belt, is mainly composed of granite and monzogranite, and mafic microgranular enclaves (MME). The identified MME has fine-grained textures, sinuous margins and diffuse contacts with the host monzogranites, and various disequilibrium textures and mineral assemblages indicate mingling or mixing processes. LA-ICP-MS zircon U-Pb dating yielded ages of 271±3Ma and 271±2Ma for the monzogranite and MME, respectively, indicating that the Mandelinwula pluton was emplaced in Permian instead of in Early Mesozoic as suggested by previous researchers. Zircon εHf(t) values of the monzogranite and enclaves show a wide range and significant overlap from -18.4 to -10.1 (with TDM 1.8~2.3Ga) and -23.6 to -9.1 (with TDM 1.7~2.5Ga), respectively. The source characteristics are similar to those of the intermediate-felsic plutons in the east part of the Yabulai-Nuoergong-Honggueryulin belt of the northern Alxa block. Combined with petrology, geochemistry and Hf-in-zircon isotope studies, the authors propose a plausible magma mixing interpretation for the Mandelinwula monzogranite and MME.
    2019  .  38(10):    1675-1690    [摘要](11)    [PDF](13)
  • Determination of Late Paleozoic metamorphic event in the Langshan area, western Inner Mongolia: New evidence from LA-ICP-MS zircon U-Pb dating of the Wulashan Group
    LIU Pinghua, ZOU Lei, TIAN Zhonghua, JI Lei and SHI Jianrong
    Wulashan Group is one of the important parts of the Precambrian basement in the Langshan area, and accurate determination of the diagenetic and metamorphic timing of the Wulashan Group is of great scientific significance for further discussing the Precambrian geological evolution of the Langshan area. In this paper, the authors carried out a detailed study of the petrological observation and zircon U-Pb dating of hornblende biotite plagioclase gneisses and related granitic leucosomes from Wulashan Group. The result of detrital zircon U-Pb dating and geological investigation of the hornblende biotite plagioclase gneisses indicates that the age of detrital zircons of the gneisses of the Wulashan Group in Langshan area ranges from 2591Ma to 1800Ma, and the youngest group age of detrital zircons is circa 1873Ma. Combined with its metamorphic age of circa 270Ma, it is preliminarily considered that the sedimentary age of the gneisses ranges from 1873Ma to 270Ma. The above and latest studies indicate that, besides Neoarchaean-Paleoproterozoic metamorphic rocks, there are also Mesoproterozoic-Late Paleozoic metasedimentary rocks within the Wulashan Group. The result of cathodoluminescence image analysis and U-Pb dating of zircons indicates that a large number of metamorphic zircons exist in the hornblende biotite plagioclase gneisses. They record a 206Pb/238U weighted average age of 269±4Ma, which represents the timing of the late Paleozoic amphibolite-facies metamorphism of the Wulashan Group in the Langshan area, probably in response to the Late Paleozoic collisional orogenesis between the North China Plate and Siberian Plate. In addition, a reliable 206Pb/238U weighted average age of 264±3Ma of the high-U zircons from the high-silica granitic leucosomes was obtained by pre-ablation dating method. The age (264±3Ma) is interpreted as the diagenetic timing of high-silica granitic leucosomes in the Wulashan Group, which represents the timing of the transformation for the collisional extrusion to post-collisional extension during late Paleozoic orogenesis.
    2019  .  38(10):    1691-1710    [摘要](8)    [PDF](10)
  • Geochemical characteristics and zircon U-Pb geochronology of the Baijiafen augamite granite in Anshan of the North China platform and its significance
    WEN Dejuan
    The genesis and chronology of Archaean TTG rocks is the key to understanding the problems concerning the beginning of the pre-plate tectonics and plate tectonics and their evolution process. It is an important sign of continental crust accretion and one of the hotspots and difficulties in the study of Archaean geologic bodies. Geochemical characteristics and zircon U-Pb dating of Baijiafen intrusion were studied in Anshan area. The data show that the rock mass has the characteristics of orthogneiss, with high Si, Na content, low TFeO, MgO, CaO content, low light and heavy REE content and some changes. The REE content of rocks is low, REE is 12.6×10-6~119.34×10-6 and LREE/HREE ratio is 8.98~13.11. Trace elements of rocks are characterized by enrichment of K, Rb and Ba and depletion of Nb, Ce, Zr, Sm, Ti, Y and Yb; K/Rb mean ratio is 229.37, Rb/Sr mean ratio is 0.58, Ba/Sr mean ratio is 3.28, and Y/Nb mean ratio is 3.36, suggesting that the rock mass is the product of magmatism, with a part being the product of intracrustal recycling or being affected by continental crustal materials. The weighted average age of 207Pb/206Pb is 3816±14Ma. The zircon has clear oscillating zonal structure. Th/U ratios of all core zircon analytical points range from 0.05 to 0.54. It has the characteristics of magmatic zircon and represents the crystallization age of Baijiafen trondhjemite. The age data of 3613~3651Ma and 3331Ma represent a magmatic event in the early Archaean and a thermal event in the important period of continental crust accretion.
    2019  .  38(10):    1711-1717    [摘要](9)    [PDF](10)
  • Zircon U-Pb age of bertonite of Upper Ordovician Wufeng Formation in Southeast Yangtze platform and its geological significance
    YE Fei, PAN Wen, ZUO Yong, YIN Tinglong, JIANG Tianrui, YANG Shengtang, YANG Guanglong, ZHOU Ling, LIU Jian, ZHAN Pengcai, ZHOU Ning and QIN Zhigui
    A layer of bentonite is usually developed in upper Ordovician and lower Silurian strata of southeast Yangtze platform in Sinan area. Sampling was done in Wufeng Formation of upper Ordovician and Longmaxi Formation of lower Silurian in Luowantuo of Sinan, high precision U-Pb dating was conducted and as a result, the stratigraphic sedimentary age of Wufeng Formation and Longmaxi Formation in this area were constrained. The data obtained provide reliable evidence for volcanic eruption and stratigraphic chronology near Ordovician and Silurian boundary of southeast Yangtze platform in Sinan area. The age data are correlated well with the data obtained in Dabashan of northwest China, which is a little later than the age of Ordovician bentonite in southeast of the North China Craton (449.0~465.8Ma). The volcanic activity was probably related to the subduction of Cathaysian plate to Yangtze plate. During Middle-Late Ordovician and late Early Silurian, many volcanic eruptions influenced the chemical condition and ecological environment of the ocean in that period and caused the extinction and glacier initiation since middle-late Ordovician.
    2019  .  38(10):    1718-1725    [摘要](9)    [PDF](8)
  • Zircon U-Pb age of the felsite porphyry veins in western Fuzhou basin of Fujian Province and its geological significance
    LIN Musen, WU Lingxiao and WANG Cuizhi
    This paper presents U-Pb zircon geochronology, petrology, and major and trace elements of Cretaceous felsite porphyry veins in western Fuzhou basin, Fujian Province. These data were used to investigate the genetic relationship between felsite porphyry and Fuzhou composite granite body. Felsite porphyry shows purplish gray color and is mainly composed of orthoclase phenocrysts, and the well-developed flow structure is present on the margin. Felsite porphyry veins have a NE-trending strike and intruded into Fuzhou composite granite body. Felsite porphyry shows the features of calc-alkali and I-type granites, with the emplacement age being 97.4Ma; it was formed in the transition period between early Fuzhou composite granite body (111~100Ma) and late Fuzhou composite granite body (95~90Ma). The geochemical characteristics between the above three phase rock types present a graduallychanged transitional relation on the time scale. That is, this felsite porphyry is the product of the tectonic regimes conversion between Early and Late Cretaceous in southeastern China. The authors thus hold that the transformation age may be 97Ma.
    2019  .  38(10):    1726-1732    [摘要](6)    [PDF](8)
  • Zircon U-Pb age, Sr-Nd isotopic characteristics and its geological significance of the granites from the Meixian zinc-lead polymetallic deposit, central Fujian Province
    XIAO Xiaoniu, FEI Lidong, YU Xinming, QIN Xinlong, XIAO E and LIU Rongfang
    In order to discuss the genesis of the granites in the Meixian orefield of central Fujian Province, this paper reports petrography, geochronology and Sr-Nd isotope data. Zircon U-Pb dating yielded an age of 158±3Ma for the Xiaojiao granites, indicating that they were formed in Late Jurassic in the middle Yanshanian period. Isotopically, sample analyses show high and variable initial ISr ratios (0.707099~0.710082) but low and constant εNd(t) (-9.79~-10.92), showing crust source characteristics obviously and indicating that Meixian granites are highly fractionated I-type granites. Combined with previous research results, it is held that the granites of the middle Yanshanian period in Meixian area were formed by the sub-reduction stretching and extension of the paleo-Pacific plate to the Eurasian plate, and were emplaced at the extention orogenic stage within the plate.
    2019  .  38(10):    1733-1739    [摘要](7)    [PDF](8)
  • The identification of Jurassic stratigraphy in southern Hainan Island: Evidence from detrital zircon U-Pb ages and Hf isotopic compositions
    HU Zailong, WANG Yong, ZHAO Xiaoming, WEI Changxin, LIN Yihua, YUAN Haijun, MENG Zhongying and WU Nianwen
    The Hainan Island has long been considered as lacking the Jurassic deposition, which suggests that Hainan Island and interior continent have different Mesozoic evolutions. In this study, the authors conducted detrital zircon U-Pb analysis for the fuchsia clastic rocks in the Jianling and Hailuoling section and the Early Cretaceous Lumuwan Formation rocks, which are located at Sanya, southern Hainan. The zircon U-Pb dating results of the fuchsia clastic rocks from the two sections illustrate similar age spectra and oldest depositional age (172~174Ma). They are completely different from the spectrum of the underlying Late Ordovician Yuhong Formation and Early Cretaceous Lumuwan Formation samples. Together with previous tectonic and igneous activity records as well as the zircon Hf isotopic characteristics of the fuchsia clastic rocks, the authors hold that the deposition of the fuchsia clastic rocks in Jianling and Hailuoling must have occurred during 172~158Ma in the Middle-Late Jurassic periods. The sedimentary provenance and tectonic background were similar to those of the contemporary sedimentary rocks in eastern Guangdong and Fujian, indicating a uniform tectonic environment during the Middle-Late Jurassic in the southeast coastal area of South China.
    2019  .  38(10):    1740-1757    [摘要](11)    [PDF](12)
  • Potash assessment models and resource potential analysis in China
    SHANG Pengqiang, QI Caiji, JIAO Sen, XIONG Xianxiao, GUAN Bingting and ZHANG Yang
    Aimed at calculating ore resources and providing proposal of scientific industrial policy, the authors carried out scientific researches on mineralization characteristics and assessment of resource potential in the past several years. The discovered potash deposits, which can be divided into 12 Ⅲ grade metallogenic belts, are mainly of Quaternary saline lake-type located in Cenozoic continental basin in western China with a Quaternary metallogenic age. On the basis of researches on typical deposits, regional metallogenic and predictive factors, four different kinds of potash metallogenic prediction models were summarized, namely Quarternary salt lake type, deep-subterranean bittern type, clastic rock type and carbonate type. Adopting comprehensive geological information model, the authors delineated 320 minimum predicting areas and 42 grade Ⅲ prediction areas. Furthermore, 3.263 billion tons of KCl at the depth shallower than 6000m and 1.51 billion tons of KCl at the depth shallower than 500m were predicted on the basis of metallogenic prediction model proposed by the authors. These researches indicate that the north Qaidam Basin and Tarim Basin carry more potash resources quantity than other places in China and the potash resources in the two basins are mainly of Quaternary salt-lake type and deep-subterranean bittern type. These resource potential predictions reveal the degree of the present study of potash deposits and are of great significance for potash prospecting.
    2019  .  38(10):    1758-1767    [摘要](12)    [PDF](16)

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