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Geochronology and Petrogenesis of Mafic-Intermediate intrusions on the Northern Margin of the Central Tianshan(NW China): Implications for Tectonic Evolution

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Journal of Earth Science 2019年第2期30卷 323-334页

作者： Hongming Cai He Yang Xiangkuan Gong School of Geology and Mining Engineering Xinjiang University Geography Postdoctoral Research Station Xinjiang University Xinjiang Research Center for Mineral Resources Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences

Late Paleozoic mafic-intermediate intrusions are widespread in the central Tianshan belt, but their tectonic settings remain controversial. Petrogenesis of these intrusions can provide insights into the tectonic evolution of the belt and its adjacent areas. This study presents new whole-rock geochemical and zircon U-Pb geochronology and Hf isotopic data for the Yaxi diorite and Qianzishan gabbro on the northern margin of the central Tianshan(NW China). Zircon U-Pb dating yielded the magma crystallization ages of 313±4 and 295±4 Ma for the Yaxi diorite and Qianzishan gabbro, respectively. They have lower Mg# values, Ni and Cr contents than typical mantle-derived primary melt, with negative correlations between MgO, TFeO and SiO2 contents, indicating clinopyroxene and olivine fractionation during magma evolution. They are characterized by enrichment of large ion lithophile elements(e.g., Rb, Ba and Sr) and depletion of high field strength elements(e.g., Nb, Ta and Ti) with high Ba/Th and Rb/Y, suggesting that their mantle sources had been metasomatized by slab-derived fluids. In addition, the Qianzishan gabbro has high Al2 O3 contents(19.54 wt.%–20.88 wt.%) and positive Eu anomalies(Eu/Eu*=1.09–1.42), which can be attributed to accumulation of plagioclase. Geochemical and zircon Hf isotopic compositions reveal that both the Yaxi diorite and Qianzishan gabbro were derived from depleted lithospheric mantle in the spinel stability field with insignificant crustal contamination. In association with previous investigations, we suggest that the Yaxi and Qianzishan intrusions were emplaced in a subduction-related environment, which means that the subduction of the Junggar Ocean lasted at least to the earliest Permian.

关键词： mafic-intermediate intrusions geochemistry petrogenesis tectonic implication central Tianshan

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intrusions of the Panxi region,China,and their magmatic ore deposits

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Geoscience Frontiers 2013年第5期4卷 479-480页

作者： Nicholas Arndt ISTerre Universite Joseph Fourier38400 St Martin d'HeresFrance

The intrusions of the Panzhihua-Xichang（Panxi） region in southwest China have become well known in the past decade because they host large and rich magmatic oxide deposits that are mined for Fe,Ti and *** intrusions form part of the Emeishan large igneous province（ELIP）,which is commonly believed to be the product of melting in a mantle *** ELIP was emplaced about 260 Ma ago,at the same time as the end-Guadalupian mass *** investigation of the Panxi intrusions therefore provides information relevant to three broad areas of the earth sciences：（1）the petrogenesis of mafic magmas,

关键词： intrusions magmatic Nicholas

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Sm-Nd age of syncollisional mafic-ultramafic intrusions in the Dabie Mountains

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Chinese Science Bulletin 1998年第2期43卷 160-163页

作者： Yonghong Nie Shuguang Li Univ Sci & Technol China Dept Earth & Space Sci Hefei 230026 Peoples R China

A Sm_Nd age of (228±42) Ma with initial ε Nd =-16.4 for the Renjiawan pyroxenite intrusion in the North Dabie terrane is reported. This age with another Sm_Nd age of (230±44) Ma for the Zhujiapu pyroxenite in the same terrane documents that the pyroxenite in the North Dabie terrane are formed during continental subduction time of the Yangtze craton in the Triassic.

关键词： Dabie Mountains mafic_ultramafic intrusions Sm_Nd chronology syncollisional igneous rocks.

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Discriminating characters of ore-forming intrusions in the super-large Chalukou porphyry Mo deposit,NE China

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Geoscience Frontiers 2018年第5期9卷 1417-1431页

作者： Peixin Duan Cui Liu Xuanxue Mo Jinfu Deng Jinhua Qin Yu Zhang Shipan Tian School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Heilongjiang Institute of Geological Survey Harbin 150036China Heilongjiang Province Institute of Regional Geology Survey Harbin 150080China

The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain *** we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum *** U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.

关键词： Greater Hinggan Range Chalukou porphyry Mo deposit Geochronology Ore-forming intrusions Mongolia-Okhotsk ocean

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Zircon U-Pb Ages and Geochemistry of Permo-Carboniferous Mafic intrusions in the Xilinhot Area, Inner Mongolia: Constraints on the Northward Subduction of the Paleo-Asian Ocean

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Acta Geologica Sinica(English Edition) 2019年第5期93卷 1261-1280页

作者： WANG Ke LI Yilong XIAO Wenjiao ZHENG Jianping Fraukje MBROUWER School of Earth Sciences State Key Laboratory of Geological Processes and Mineral ResourcesChina University of GeosciencesWuhan 430074China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Geology and Geochemistry Group Department of Earth SciencesVU AmsterdamDe Boelelaan 10851081 HV AmsterdamThe Netherlands

The Central Asian Orogenic Belt(CAOB) resulted from accretion during the Paleozoic subduction of the PaleoAsian Ocean. The Xilinhot area in Inner Mongolia is located in the northern subduction zone of the central-eastern CAOB and outcropped a large number of late Paleozoic mafic intrusions. The characteristics of magma source and tectonic setting of the mafic intrusions and their response to the closure process of the Paleo-Asian Ocean are still controversial. This study presents LA-ICPMS zircon U-Pb ages and geochemical features of mafic intrusions in the Xilinhot area to constrain the northward subduction of the Paleo-Asian Ocean. The mafic intrusions consist of gabbro, hornblende gabbro, and diabase. Their intrusion times can be divided into three stages of 326-321 Ma, 276 Ma and 254 Ma by zircon U-Pb ages. The first two stages of the 326-276 Ma intrusions mostly originated from subduction-modified continental lithospheric mantle sources that underwent a variable degree partial melting(5-30%), recording the subduction of oceanic crust. The third stage of the 254 Ma mafic rocks also show arc-related features. The primary magma compositions calculated by PRIMELT2 modeling on three samples of ~326 Ma and two samples of ~254 Ma show that these mafic samples are characterized by a variable range in SiO2(47.51-51.47 wt%), Al2O3(11.46-15.55 wt%), ΣFeO(8.27-9.61 wt%), MgO(13.01-15.18 wt%) and CaO(9.13-11.67 wt%), consisting with the features between enriched mantle and lower continental crust. The source mantle melting of mafic intrusions occurred under temperatures of 1302-1351°C and pressures of 0.92-1.30 GPa. The magmatic processes occurred near the crust-mantle boundary at about 33-45 km underground. Combined with previous studies, it is concluded that Carboniferous to early Permian(~326-275 Ma) northward subduction of the Paleo-Asian oceanic crust led to the formation of the mafic magmatism in the Baolidao arc zone. The whole region had entered the collision environ

关键词： LA-ICPMS zircon U-Pb age geochemistry mafic intrusions Paleo-Asian Ocean Central Asian Orogenic Belt

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Multiphase porphyry intrusions in the Sungun copper deposit,NW Iran:Evidence from SHRIMP zircon U-Pb dating

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China Geology 2019年第2期2卷 240-242页

作者： Hong-rui Zhang Zeng-qian Hou Tian-nan Yang Zhi-ming Yang Jian-lin Chen Mehraj Aghazadeh Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesChina Geological SurveyMinistry of Natural ResourcesBeijing 100037China State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China Department of Geology Payame Noor UniversityTehran 19395-4697Iran

*** The porphyry copper deposits (PCD) are usually hosted in a multistage intrusive complex but only causallyrelated tospecific magma of high oxidation state and water content. The copper enrichment of the porphyry system is caused by accumulation during magmatic differentiation (Hou ZQ et al., 2015). Thus, study on magmatic evolution and Cu mineralization process is important for understanding the formation of PCD.

关键词： NW Iran Sungun copper deposit Multiphase porphyry intrusions

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Granitoid intrusions and related deposits

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Science China Earth Sciences 1996年第1期39卷 1-6页

作者：孟良义李绪俊 Department of Geology Changchun University of Earth Scienoes Changchun 130026 China

Taking the Bainaimiao copper and gold deposits, Inner Mongolia and the Wushan copper deposits, Jiangxi Province as examples, a discussion is devoted to the relationship between the granitoid intrusions and related deposits from different lines of evidence: the spatial distribution, country rocks and alteration of the deposits, trace element contents and vertical zoning of elements in deposits, the metallogenic preference of granitoid intrusions, the metallogenic models and stable isotopic geology. It is concluded that the ore-bearing fluids mainly come from granitoid magmas and granitoid intrusions are closely associated with the related deposits in space.

关键词： granitoid intrusions hydrotfaennal deposit anomalous geological phenomena.

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Atmospheric deposition of 7Be,210Pb and 210Po during typhoons and thunderstorm in Shanghai, China and global data synthesis

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Science China Earth Sciences 2020年第4期63卷 602-614页

作者： Juan DU Mark BASKARAN Jinzhou DU State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200241China Department of Geology Wayne State UniversityDetroit 48202USA

Atmospherically-delivered ~7Be,^(210)Po and ^(210)Pb in bulk precipitation and air samples collected around the globe have provided valuable quantification on the rates of removal, as well as proportional mixing of attendant air masses;however, such studies during thunderstorm and typhoon events are limited. We report the first continuous time-series rainwater sampling and analysis of ~7Be,^(210)Pb and ^(210)Po from two typhoons and one thunderstorm during 2015 summer in Shanghai. The depositional fluxes within individual rain events of typhoons and thunderstorms varied by a factor of 10 for ~7Be, 5.7 for ^(210)Pb, 7.4 for ^(210)Po,and 7.0 for ~7Be/^(210)Pb activity ratios(AR). Such large observed variations in the depositional fluxes of ~7Be,^(210)Pb,^(210)Po and ~7Be/^(210)Pb activity ratios were attributed to air masses injected from surrounding high pressure system adjoining the typhoon to low pressure system within the typhoon. Based on ~7Be/^(210)Pb activity ratios, we estimated the variations in the fraction of maritime and continental air masses into the typhoon. Observed constancy in the ^(210)Po/^(210)Pb AR indicates that the residence times of air masses contributing to the typhoon during heavy rain are similar. From a synthesis of global fallout of ~7Be and ^(210)Pb during pulse events(precipitation≥50 mm from single rainout event), we quantify the importance of pulse events in the atmospheric fallout of these radionuclides.

关键词： 7Be 210Pb 210Po Typhoon Thunderstorm Air masses intrusions

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Time scales and length scales in magma ?ow pathways and the origin ofmagmatic Ni-Cu-PGE ore deposits

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Geoscience Frontiers 2019年第1期10卷 77-87页

作者： Stephen J.Barnes Jesse C.Robertson CSIRO Mineral Resources

Ore forming processes involve the redistribution of heat, mass and momentum by a wide range of processes operating at different time and length scales. The fastest process at any given length scale tends to be the dominant control. Applying this principle to the array of physical processes that operate within magma flow pathways leads to some key insights into the origins of magmatic Ni-Cu-PGE sulfide ore deposits. A high proportion of mineralised systems, including those in the super-giant Noril'sk-Talnakh camp, are formed in small conduit intrusions where assimilation of country rock has played a major role. Evidence of this process is reflected in the common association of sulfides with varitextured contaminated host rocks containing xenoliths in varying stages of assimilation. Direct incorporation of S-bearing country rock xenoliths is likely to be the dominant mechanism for generating sulfide liquids in this setting. However, the processes of melting or dissolving these xenoliths is relatively slow compared with magma flow rates and, depending on xenolith lithology and the composition of the carrier magma, slow compared with settling and accumulation rates. Chemical equilibration between sulfide droplets and silicate magma is slower still, as is the process of dissolving sulfide liquid into initially undersaturated silicate magmas. Much of the transport and deposition of sulfide in the carrier magmas may occur while sulfide is still incorporated in the xenoliths, accounting for the common association of magmatic sulfide-matrix ore breccias and contaminated "taxitic" host rocks. Effective upgrading of so-formed sulfide liquids would require repetitive recycling by processes such as reentrainment, back flow or gravity flow operating over the lifetime of the magma transport system as a whole. In contrast to mafic-hosted systems, komatiite-hosted ores only rarely show an association with externally-derived xenoliths, an observation which is partially due to the pre

关键词： Magmatic ore deposits Assimilation intrusions Nickel Norilsk Komatiites

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Geology, Geochronology, and Hf Isotopic Composition of the Pha Lek Fe Deposit, Northern Laos: Implications for Early Permian Subduction-Related Skarn Fe Mineralization in the Truong Son Belt

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Journal of Earth Science 2019年第1期30卷 109-120页

作者： Lin Hou Shusheng Liu Linnan Guo Fuhao Xiong Chao Li Meifeng Shi Qiming Zhang Siwei Xu Songyang Wu Chengdu Center China Geological Survey Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation of Ministry of Land and Resources Chengdu University of Technology National Research Center of Geoanalysis Chinese Academy of Geological Science China University of Geosciences

The Truong Son metallogenic belt in central Laos and Vietnam is an important Fe-Cu-Sn-Au polymetallic ore district. The Pha Lek Fe deposit is closely related to Late Carboniferous– Early Permian I-type granitic magmatism, and contains >50 Mt @ 45% to 50% of Fe ore. Ore minerals occur mainly as magnetite and hematite in the skarn alteration zone between a granitic pluton and metamorphosed Middle–Upper Devonian carbonates. The granitic pluton comprises granodiorite and granite, with zircon U-Pb dating indicating synchronous emplacement at 288.2±1.3 and 284.9±1.2 Ma, respectively. Zircons from these granitoids have ε_(Hf)(t) values of 2.9–11.2 and relatively young TDM2 ages(<1.0 Ga), indicating an origin by partial melting of depleted mafic crust or magma mixing. Previous studies have shown that these granitoids have high Y, Yb, and K_2O contents, and low Sr and Na_2O contents, which are interpreted as the melting of mafic continental crust. Pyrite of the main mineralization stage yields an ^(187)Re/^(188)Os-^(187)Os/^(188)Os isochron age of 287±17 Ma, indicating that mineralization is associated with Pha Lek granitic magmatism. A Late Carboniferous–Early Permian subduction-related skarn-type Fe mineralization model is proposed for the Pha Lek deposit. More evidence is needed to verify a hypothesis of volcanic overprinting during Late Triassic post-collisional extension.

关键词： Truong Son belt Pha Lek Fe deposit granitic intrusions geochronology Hf isotopic composition.

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