Nanjing Institute of Geology and Mineral Resources

Nanjing, China

Nanjing Institute of Geology and Mineral Resources

Nanjing, China
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Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Li H.-K.,Tianjin Institute of Geology and Mineral Resources | Santosh M.,Kochi University | Santosh M.,China University of Geosciences
Terra Nova | Year: 2013

New field observations and zircon U-Pb age data, combined with previous studies, are employed here to evaluate the process of assembly of the Yangtze and Cathaysia Blocks. We show that the process started from the west prior to 1.0 Ga and migrated eastward with the final amalgamation along the suture at around 830-820 Ma. During the period of 850-820 Ma, both the mantle plume which possibly started at 850 Ma and the north-directed plate subduction along the southern margin of the Yangtze Block controlled the formation and closure of a back-arc basin along the middle to eastern segment of the Yangtze Block, as well as the diverse and complex magmatic activities. The closure of the back-arc basin and almost synchronous rift basin overlying the folded "basement" sequence mark the termination of subduction when the Rodinia plume exerted a dominant control on the evolution of the middle to late Neoproterozoic basin and the related magmatic pulses. © 2013 Blackwell Publishing Ltd.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Santosh M.,China University of Geosciences | Zou H.-B.,Auburn University | Li H.-K.,Tianjin Institute of Geology and Mineral Resources | Huang W.-C.,Nanjing Institute of Geology and Mineral Resources
Lithos | Year: 2013

The Fuchuan ophiolite occurs along the easternmost domain of the Jiangnan Orogen, considered as the suture between Yangtze and Cathaysia Blocks in South China. Here we report results from our new field observations, zircon U-Pb ages and Hf isotope of the cumulate units, chemistry and tectonic discrimination of Cr-spinel from the harzburgite, and whole rock geochemistry of the pillow lava from the ophiolite in an attempt to evaluate the Neoproterozoic tectonic evolution of South China. The zircon data indicate that the ophiolite suite formed at 840-820Ma, and the high εHf(t) (8-13) and εNd(t) (3.3-5.7) values suggest that the cumulates were derived from significantly depleted mantle sources. The pillow lavas and the keratophyres, show typical calc-alkalic continental arc-signatures including the enrichment in LREE and LILE, and depletion in HFSE (Nb/La=0.3 to 0.5) and a wide range of εNd(t) values (-1.2 to 2.5). The chromium-spinels from the serpentinized harzburgite show Cr# ranging from 40 to 67 and Mg# from 33 to 60 comparable with the chemistry of spinels from suprasubduction zone (SSZ)-type ophiolites. The geochemical features as well as the association of coeval I-S type granites and several thousand meters of flysch-type sedimentary sequences correlate the Fuchuan ophiolite to SSZ-type. We suggest that the emplacement of the Fuchuan ophiolite suite marks the time of final welding between the Yangtze and Cathaysia blocks in South China at ca.820Ma. © 2013 Elsevier B.V.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Xu Y.-G.,CAS Guangzhou Institute of Geochemistry | Li Z.-X.,Curtin University Australia | Wang H.-Y.,Nanjing Institute of Geology and Mineral Resources | Ye H.-M.,Nanjing Institute of Geology and Mineral Resources
Lithos | Year: 2010

Zircon U-Pb ages and geochemical data are reported for the Piqiang oxide-bearing ultramfic-mafic complex, the Bachu mafic dyke swarm, the Yingan and Kaipaizileike basalts and the Halajun A-type granites in the Tarim Block, Northwest China. The Piqiang complex and the Halajun A-type granites were emplaced at ca. 276Ma and ca. 278Ma, respectively. Together with previously reported geochronological data, the diverse intrusive and extrusive rocks in Tarim show a peak age at ca. 275Ma. Elemental and Nd isotope geochemistry suggests that the spatially and temporally related Piqiang complex (including some dolerite dykes or stocks) and the Halajun A-type granites were formed via crystal fractionation/accumulation of a common plume-derived parental mafic magma (melting degree >10%), coupled with variable extents of crustal contamination. Crystal fractionation/accumulation in one or several magma chambers resulted in the diversity of rocks types. The Bachu mafic dyke swarm shares a similar mantle source with the intrusive rocks in the Piqiang-Halajun area but with a relatively lower degree of partial melting (~5%). In contrast, the basalts were derived from a time-integrated, enriched lithospheric mantle source as suggested by their high-Ti, LREE- and LILE-enriched trace element signature and negative εNd(t) values (-2.0 ~ -2.6). The synchronous yet diverse range of Permian igneous rocks in Tarim can best be accounted for by a Permian mantle plume, which is about 15Ma earlier than the Emeishan plume in southwestern China. © 2010 Elsevier B.V.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Yang D.-S.,CAS Guangzhou Institute of Geochemistry | Wang H.-Y.,Nanjing Institute of Geology and Mineral Resources | Takahashi Y.,Geological Survey of Japan | Ye H.-M.,Nanjing Institute of Geology and Mineral Resources
Gondwana Research | Year: 2011

In this paper we report zircon U-Pb age, chemical compositions of rock-forming minerals, and whole-rock elemental and Sr-Nd isotopic data for the No. II mafic-ultramafic intrusive complex (N2MC) in the Quruqtagh area at the northeastern margin of the Tarim Block, northwestern China to evaluate its petrogenesis and tectonic significance. The N2MC with an exposure area of ca. 12km2 has a funnel-shaped cross-section and intruded the Paleoproterozoic basement. U-Pb zircon dating gives a crystallization age of 760±6Ma. Rock types of the N2MC include lherzolite, pyroxenite, gabbro and minor diorite. Major elements geochemistry of these rocks exhibits a tholeiitic trend with a wide range of SiO2 contents (38.8-60wt.%). On the other hand, they are systematically enriched in LILE, LREE and depleted in HFSE and HREE, thus leading to low HFSE/LREE ratios (e.g., Nb/La≈0.3). Isotopically, the studied rocks are characterized by negative whole-rock εNd(t) values (-7.6 to -2.8) and variable high (87Sr/86Sr)i (0.7095-0.7059). These features, together with chemical compositions of the rock-forming minerals and the presence of the primary phlogopite and hornblende, suggest that N2MC was likely formed via crystal fractionation/cumulation (with negligible crustal contamination) of a tholeiitic magma derived from a metasomatized subcontinental lithosphere mantle (SCLM) in an extensional environment. The enrichment of the mantle source could be ascribed to the metasomatism by subducted-slab-released fluids before partial melting. Overall, reported Neoproterozoic igneous rocks throughout the Tarim Block constitute two major phases of Neoproterozoic igneous activities, i.e., ca. 825-800Ma and ca. 780-745Ma, respectively. Similar to that of many other Rodinian continents, this feature is interpreted to be related to the two phases of Neoproterozoic mantle plume activity under the Rodinia. Furthermore, there exist two types of mafic-ultramafic complex at Quruqtagh, i.e., the ca. 820Ma carbonatite-bearing and the ca. 760Ma tholeiitic, which could reflect the presence of two different mantle sources. © 2010 International Association for Gondwana Research.


Ages and chemical and isotopic compositions of the Permian mafic dyke swarms from Kelamayi, eastern Tianshan and western Tianshan in western part of the Central Asian Orogenic Belt (CAOB), NW China, are reported here in order to gain more insights into the Permian Tarim Large Igneous Province (Tarim LIP). These CAOB mafic (-andesitic) dyke swarms from Kelamayi, eastern Tianshan and western Tianshan were emplaced at 267±3Ma, 278±2Ma and 260-290Ma, respectively, and are coeval with the radiating mafic dyke swarm in the Tarim Block. The dykes in CAOB exhibit subalkalic character in major element compositions, and are enriched in LILE and LREE and depleted in HFSE and HREE, with the exception of a few LREE-depleted samples from western Tianshan. Isotopically, dykes from Kelamayi and western Tianshan are characterized by significant positive εNd(t) values (3.1 to 7.9 for Kelamayi; 7.2 to 7.3 for western Tianshan), while dykes form eastern Tianshan exhibit variable negative εNd(t) values (-0.7 to -3.3). Their geochemical features suggest that the mafic (-andesitic) dykes in CAOB were derived from a recently metasomatized lithospheric mantle source (sub-continental lithosphere mantle) with subsequent variable extents of assimilation of the crustal materials in a non-orogenic setting. In contrast, the mafic dykes in Tarim exhibit systematic chemical signatures similar to those of OIB, indicating that they were derived from a depleted sub-lithospheric mantle source. We thus propose that the Permian Tarim LIP has two different mantle domains for the coeval mafic rocks, i.e., the Tarim domain and the CAOB domain. © 2012 Elsevier B.V.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Zou H.-B.,Auburn University | Li H.-K.,Tianjin Institute of Geology and Mineral Resources | Wang H.-Y.,Nanjing Institute of Geology and Mineral Resources
Gondwana Research | Year: 2013

The Tarim Block is characterized by a double layer structure consisting of a Precambrian basement and Neoproterozoic to Cambrian cover series. It experienced different stages of tectonic evolution since its generation, with similarities and dissimilarities to the North and South China Blocks in many aspects. This has brought about complexities in understanding the tectonic processes of crustal growth and reworking in the Tarim Block. In this contribution, we provide a comprehensive synthesis on the regional geology and analytical data. Based on the study herein, we constructed its tectonic framework and main evolution stages and its sedimentary-magmatic-metamorphic concurrence to the main tectonic events. In the Archean, the 2.80-2.57. Ga Archaean TTG was intruded by the ca.2.53. Ga high Ba-Sr granite, leading to the formation of the Archean proto crust of the Tarim. During the Proterozoic, two periods of tectono-metamorphic events occurred in the Orosirian-Statherian period (2.0-1.8. Ga) and the late Mesoproterozoic to early Neoproterozoic (1.0-0.9. Ga), respectively. They were concurrent with the global assembly of Columbia and Rodinia supercontinents, respectively. Since 760. Ma, Tarim and other landmasses started to split from Rodinia in response to the Rodinian breakup. In the middle to late Neoproterozoic, the Rodinia breakup resulted in the diverse and voluminous intriguing igneous activities along the northern margin of the Tarim. In the Early Cambrian, the Tarim Block drifted away from the other parts of Rodinian landmass in response to the Pan-African tectonic event. During the late Neoproterozoic to the Carboniferous, the early Paleozoic Northern Kunlun orogen was produced by collision of the Qaidam with the southern margin of Tarim, whereas in the late Paleozoic the southern Tianshan orogen was brought about due to collision between the Yili terrane and the northern margin of Tarim. In the Permian, a large igneous province occurred in Tarim, which is the last igneous activity in this block. © 2012 International Association for Gondwana Research.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Zou H.-B.,Auburn University
Lithos | Year: 2013

Zircon U-Pb ages, whole-rock geochemical and zircon Hf isotope data are reported for the Permian A-type quartz syenites-granites in western Tarim Block, Northwest China. Zircon U-Pb dating indicates these alkali plutons were emplaced at 270-277Ma. Elemental geochemistry shows their typical A-type signatures, i.e., high total alkali, HFSE, REE contents and Ga/Al, FeOtot/(FeOtot+MgO) and Nb/Y ratios. Isotopically, their epsilon Nd values vary from -2.6 to 2.0. Based on zircon Hf isotope compositions, they could be divided into two sub-groups: Group I exhibits high positive εHf(t) ranging from 3 to 11 (mostly within the range of 5 to 9), which is highly comparable with the syenites in Bachu area located just south of these plutons. Group II has εHf(t) ranging from -3 to 2. The second group exhibits comparable Nd-Hf isotope compositions with the spatially and temporally related Piqiang ultramafic-mafic complex. Integrating geological, geochemical and Nd-Hf isotope data, we suggest that the A-type syenite-granites were formed via intensive crystal fractionation from a common plume-derived parental mafic magma, coupled with variable extent of crustal contamination. Moreover, the extent of the crustal contamination increase from inner Tarim towards South Tianshan Collisional Belt.A comprehensive synthesis of the coeval A-type granites in the western part of the Central Asian Orogenic Belt (CAOB) shows that they exhibit distinct geochemical features, e.g., large range of εNd(t) and (87Sr/86Sr)i values, high Y/Nb, Yb/Ta and low Nb/La ratios. All these features argue that they were derived from juvenile mafic crust with variable addition of the mafic materials from mantle sources and some old crustal materials or mixing of mantle-derived mafic magma with Precambrian crustal components. We suggest that both the Permian A-type granites from Tarim and western section of CAOB were genetically linked to the Permian Tarim mantle plume, which is concurrent with the two mantle domains for the Permian Tarim Large Igneous Province (LIP). © 2013 Elsevier B.V.


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Zou H.-B.,Auburn University | Wang H.-Y.,Nanjing Institute of Geology and Mineral Resources | Li H.-K.,Tianjin Institute of Geology and Mineral Resources | Ye H.-M.,Nanjing Institute of Geology and Mineral Resources
Precambrian Research | Year: 2012

Neoproterozoic igneous rocks are widely distributed in the Quruqtagh along the northern margin of the Tarim, NW China. Here we report ages, petrography, and geochemistry of two (No. I and No. IV) Neoproterozoic bimodal intrusive complexes and Zhongtuzhan ultramafic dykes in the Quruqtagh, in order to construct a new model of Neoproterozoic tectonic evolution of the Tarim during the breakup of Rodinia. The No. I (̃20km2) and No. IV (̃10km2) bimodal intrusive complexes in Quruqtagh are composed of gabbroic and granitic rocks. New U-Pb ages of the zircons from the two intrusive complexes demonstrate that they were coevally emplaced at ca. 735Ma. The Zhongtuzhan ultramafic dykes were emplaced at ca. 802Ma, broadly coeval with the nearby Qieganbulake ultamafic-mafic-carbonatite complex.The gabbroic rocks from both No. I and No. IV complexes exhibit tholeiitic characters, enrichment in LILE and LREE, and depletion in HFSE and HREE. Isotopically, they are characterized by wide range of whole-rock εNd(t) values (0 to -0) and variable high (87Sr/86Sr)i (0.7095-0.7059). Zircons from the gabbroic samples of the No. I and No. IV complexes have slightly different εHf(t) (-1.5-0.9 and -2.5 to -0.5, respectively), indicating Nd-Hf isotopic decoupling. Zircons from Zhongtuzhan ultramafic dykes have pronounced negative εHf(t) (-14.9 to -11.9), resembling the Hf isotopic compositions of the baddeleyites from the Qieganbulake carbonatite. These features, combined with the presence of the primary phlogopite and hornblende, suggest that the gabbroic rocks were likely formed via combined crustal assimilation and crystal fractionation/cumulation (AFC effects) of a tholeiitic magma originally derived from a metasomatized subcontinental lithosphere mantle (SCLM). In comparison, the granites mingled into the No. I complex display adakitic signatures and pronounced negative εNd(t) values (≤-12), and were derived from partial melting of mafic lower crust due to the underplating of the coeval mafic magma.Our results, in conjunction with previous data in literature, indicate that the Neoproterozoic igneous activities in Quruqtagh could be broadly divided into four phases. They are as follows: (1) the ca. 820-800Ma ultramafic-mafic-carbonatite complex and voluminous adakitic granites and mafic dyke swarm; (2) the ca. 780-760Ma tholeiitic ultramafic-mafic complex and voluminous mafic dyke swarm; (3) the ca. 740-735Ma bimodal complex and bimodal volcanic series; and (4) minor 650-635Ma mafic dykes. The Neoproterozoic igneous activities waned since 740Ma as a result of the dispersing of Tarim from Rodinia. The presence of voluminous mafic rocks of arc-signature and the calc-alkaline granites in this area is due to the interaction between the Rodinian plume and oceanic crust subduction under the Tarim continent before 760Ma. As the Tarim Block was at the periphery of the Rodinia, subduction along the northern margin of the Tarim could last from late Mesoproterozoic to mid-Neoproterozoic (ca. 760Ma). During the subduction, the Rodinian plume (pulses of 825-800 and 780-740Ma) could heat the lithospheric mantle under the continental arc along the northern margin of Tarim, leading to the formation of the voluminous and diverse igneous rocks of arc-signatures. The subduction ceased at ca. 760Ma. The ca. 735Ma bimodal intrusive complex and the coeval Beiyixi basalt unconformably overlying on the ca. 820-800Ma granites, might indicate the dispersing of the Tarim from Australia. © 2011 Elsevier B.V.


Xu Z.-Q.,Chinese Academy of Geological Sciences | He B.-Z.,Chinese Academy of Geological Sciences | Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Zhang J.-X.,Chinese Academy of Geological Sciences | And 2 more authors.
Precambrian Research | Year: 2013

Based on new petrographic observations and zircon U-Pb geochronological data of the Precambrian basement from deep drilling cores in the Tarim basin and comparison with the Precambrian basements surrounding orogenic belts of the Tarim basin, we reconstruct a possible unified Tarim block. Data presented in this contribution lead to a three-fold subdivision of the pre-900. Ma basement of the Tarim block into the North Tarim terrane, the South Tarim terrane and the Central Tarim terrane. The North Tarim terrane containing Precambrian basements of the northern part of the Tarim basin, the Korla-Kuluketage and the Dunhuang area possesses a ca. 2.7-2.5. Ga or an even older continental nucleus and underwent multiple phases of magmatic and metamorphic events at ca. 2.0-1.8. Ga, 1.0-0.8. Ga and 760-687. Ma. The South Tarim terrane including Precambrian basements of the southern part of the Tarim basin, eastern Kunlun and western Kunlun orogenic belts, possesses a 2.4-2.3. Ga continental nucleus and underwent 2.0-1.75. Ga and 1.0-0.8. Ga metamorphic and magmatic events. The Central Tarim terrane encompassing Precambrian basement of the central part of the Tarim basin and the Altun orogenic belt, is characterized by magmatic arc system during 940-890. Ma. The unified Tarim Block was assembled as part of Rodinia supercontinent after series of geological processes, e.g. (1) breakup between the North and South Tarim terranes, (2) formation of the Central Tarim ocean, (3) subduction-related magmatic arc accretion, and (4) finally amalgamation of the North and South Tarim terranes during 1.0-0.8. Ga. There are two phases of the middle Neoproterozoic magmatic activities at 820-760. Ma and 760-687. Ma, respectively. They were most possibly related to the two phases of the Rodinia plume activities. The late Mesoproterozoic to Sinian assembly and breakup of the Rodinia led to the typical double-layered structure of the Tarim Block, i.e. the Pre-Nanhuaian basement and the Nanhuaian to Sinian cover sequence. Based on this study, we suggest that the unified Tarim Block, composed of Precambrian basement of Tarim basin and its surrounding orogenic belts, should be more large than the present Tarim basin. © 2013 Elsevier B.V.


Chen Z.-H.,Nanjing Institute of Geology and Mineral Resources | Xing G.-F.,Nanjing Institute of Geology and Mineral Resources
International Geology Review | Year: 2013

We present zircon U-Pb ages, Hf isotopes, and whole-rock geochemistry of the Xiaochuan gneissic granite intrusion, SE China, to constrain its petrogenesis and provide insights into early crustal evolution of the Cathaysia Block. LA-ICP-MS zircon U-Pb dating of a representative sample yields a weighted mean 206Pb/207Pb age of 1839 ±16 Ma, interpreted as the emplacement age of the Xiaochuan granite. Zircons have εHf(t) values ranging from-8.1 to 2.7 and T DM2 model ages from 2.23 to 3.03 Ga. The granites are strongly peraluminious (A/CNK = 1.14-1.41), with relatively high FeOt, TiO2, and CaO/Na2O, and low CaO, Al2O3/TiO2, and Rb/Sr values. In addition, they show strongly negative Ba, Sr, Nb, and Ta and positive Th and Pb anomalies in the primitive mantle-normalized spider diagram, similar to other Cathaysia Palaeoproterozoic S-type granites. The geochemical and Hf isotopic signatures suggest that the Xiaochuan gneissic granites were generated by partial melting of Archaean crustal materials in an intraplate extensional setting. Our results, combined with existing geochronological data, further demonstrate that the Wuyishan terrane is underlain by Palaeoproterozoic crystalline basement. © 2013 Copyright 2013 Taylor & Francis.

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