Tianjin Institute of Geology and Mineral Resources

Tianjin, China

Tianjin Institute of Geology and Mineral Resources

Tianjin, China
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Liang X.,China University of Geosciences | Wang G.,China University of Geosciences | Yuan G.,China University of Geosciences | Liu Y.,Tianjin Institute of Geology and Mineral Resources
Gondwana Research | Year: 2012

The Late Paleozoic Qomo Ri Accretionary Complex (QRAC) in the Central Qiangtang region of Tibet lies at the southern margin of the Longmu Co-Shuanghu suture. QRAC is tectonically linked with the Nierong and Jitang metamorphic complexes in eastern Tibet and the Yunling and Lancang complexes in western Yunnan province, SW China. This metamorphic complex is mainly composed of Late Paleozoic passive continental marginal strata of the South Qiangtang basin, which was underthrust beneath North Qiangtang in the Late Triassic. At least three stages of deformation, D 1, D 2 and D 3, with two corresponding metamorphic events, M 1 and M 2, were identified within the QRAC. D 1 is characterized by a penetrative foliation, S 1, bearing a dextral shear and a corresponding M 1 mineral assemblage of phengite, garnet and quartz. This deformation was interpreted to be the result of the northwestward oblique subduction of the Paleo-Tethys Ocean and dated at 211-219Ma by phengite 40Ar/ 39Ar ages. D 2, a subsequent compression deformation, followed D 1 immediately and exhibits flexural folds and pervasive axial crenulation in foliation S 2. Deformations from D 1 to D 2 indicate that an oblique oceanic subduction was immediately followed by a collision between the North and South Qiangtang blocks along the Longmu Co-Shuanghu suture. The D 3, recorded by minor folds and divisional axial cleavage (S 3), is related to a giant arc structure with an extension of ~50km. © 2011 International Association for Gondwana Research.


Wang Y.,China University of Geosciences | Zhou L.,Chinese Academy of Geological Sciences | Zhao L.,Tianjin Institute of Geology and Mineral Resources
Gondwana Research | Year: 2013

Reactivation of cratonic basement involves a number of processes including extension, compression, and/or lithospheric delamination. The northern margin of the North China Craton (NCC), adjacent to the Inner Mongolian Orogenic Belt, was reactivated in the Late Paleozoic to Early Mesozoic. During this period, the northern margin of the NCC underwent magmatism, N-S compression, regional exhumation, and uplift, including the formation of E-W-trending thick-skinned and thin-skinned south-verging folds and south-verging ductile shear zones. zircon U-Pb SHRIMP ages for mylonite protoliths in shear zones which show ages of 310-290Ma (mid Carboniferous-Early Permian), constraining the earliest possible age of deformation. Muscovite within carbonate and quartz-feldspar-muscovite mylonites from the Kangbao-Weichang and Fengning-Longhua shear zones defines a stretching lineation and gives 40Ar/39Ar ages of 270-250Ma, 250-230Ma, 230-210Ma, and 210-190Ma. Deformation developed progressively from north to south between the Late Paleozoic and Triassic. Exhumation of lower crustal gneisses, high-pressure granulites, and granites occurred at the cratonic margin during post-ductile shearing (~220-210Ma). An undeformed Early Jurassic (190-180Ma) conglomerate overlies the deformed rocks and provides an upper age limit for reactivation and orogenesis. Deformation was induced by convergence between the southern Mongolia and North China cratonic blocks, and the location of this convergent belt controlled later deformation in the Yanshan Tectonic Province. This province formed as older E-W-trending Archean-Proterozoic sequences were reactivated along the northern margin of the NCC. This reactivation has features typical of cratonic basement reactivation: compression, crustal thickening, remelting of the mid to lower crust, and subsequent orogenesis adjacent to the orogenic belt. s of the region transformed from cratonic to orogenic. © 2013 International Association for Gondwana Research.


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.


Yu S.,Chinese Academy of Geological Sciences | Zhang J.,Chinese Academy of Geological Sciences | Li H.,Tianjin Institute of Geology and Mineral Resources | Hou K.,Chinese Academy of Geological Sciences | And 2 more authors.
Gondwana Research | Year: 2013

In this study, we link zircon UPb SHRIMP and LA-ICP-MS geochronology and the LuHf isotopic composition of eclogites and their host gneisses/schists with whole-rock geochemistry of eclogites in the Dulan area to constrain their protoliths and metamorphic relationships. UPb dating suggests that the protolith of one of the eclogites was a Neoproterozoic mafic intrusive rock (828±58Ma) and the protolith of enclosing orthogneiss was an early-Neoproterozoic granitoid (923±12Ma). Detrital zircons from Grt-bearing mica-schists yield ages of 0.9-2.5Ga, with a dominant range of 1.0-1.8Ga, indicating sedimentary sources from Neoproterozoic to Neoarchean crust and a depositional age ≤0.9Ga. The matching metamorphic ages of eclogites (438±5Ma, 436±4Ma) and their country rocks (Grt-bearing mica-schists: 438±4Ma, 439±8Ma; orthogneiss: 427±8Ma) indicate that all studied samples experienced coeval Early Paleozoic HP/UHP metamorphism. The UPb ages and Hf isotopic compositions of the inherited magmatic zircon cores of an eclogite sample (εHf (800)=2.6-9.2, TDM1=1.0-1.3Ga, TDM2=1.1-1.4Ga) suggest that the protolith may be derived from Neoproterozoic depleted mantle with variable proportions of an older crustal component. The magmatic zircon cores of the orthogneiss (εHf (900)=-7.3 to -0.2; TDM2=1.8-2.1Ga) suggest that the parental magma was derived from a Paleoproterozoic crustal source. Hf isotopic compositions of the detrital zircons from the metasediments (εHf(t)=-19.4 to +10.6) suggest three crust formation and reworking events: (1) Archean (TDM2=2.7-2.9Ga) juvenile crust reworked at ~2.5Ga; (2) early Paleoproterozoic (TDM2=2.3-2.5Ga) juvenile crust reworked at ~1.8Ga; and (3) late Paleoproterozoic (TDM2=1.5-1.9Ga) juvenile crust reworked in the Neoproterozoic.Whole-rock geochemical data suggest that the protoliths of the Dulan eclogites were probably derived from a continental rift or an incipient oceanic basin rather than a large, long-lived ocean basin. Thus, combined with field relationships, petrology, geochemistry, zircon U. Pb dating and the Lu. Hf isotopic analysis presented in this paper and reported from previous studies, we suggest that the Dulan eclogites and their country rocks experienced a common UHP metamorphism during Late Ordovician deep continental subduction. © 2012 International Association for Gondwana Research.


Liu C.,Chinese Academy of Geological Sciences | Zhao G.,University of Hong Kong | Liu F.,Chinese Academy of Geological Sciences | Shi J.,Tianjin Institute of Geology and Mineral Resources
Lithos | Year: 2014

The Lu¨liang Complex is located at the western margin of the middle segment of the Trans-North China Orogen, along which the Western and Eastern Blocks amalgamated to form the basement of the North China Craton. The complex consists of the Paleoproterozoic granitic plutons and meta-supracrustal rocks, of which the latter are subdivided into the Jiehekou, Lu¨liang, Yejishan, and Heichashan/Lanhe Groups. A meta-volcanic rock from the Yejishan Group gives a magmatic zircon U-Pb age of 2188±48Ma and εHf(t) values of +0.06 to +5.42. Based on the geochemical characteristics, four different ~2.2Ga igneous rock suits have been identified in the Lu¨liang Complex. The calc-alkaline basalts and andesites show the geochemical features of typical 'normal' arc volcanics with pronounced LREE enrichments relative to HREE, negative Nb, Ta, P and Ti anomalies and εNd(t) values of -2.69 to +2.14. The adakitic rocks are characterized by high Na2O/K2O ratios, weak to positive Eu anomalies, positive Sr and Ba but negative Nb and Ti anomalies, and relatively clustered and near to zero εNd(t) values. The Nb-enriched basalts and andesites have higher Nb, Zr and TiO2 contents, higher Nb/Ta (14.4-19.3) and Nb/U (20.6-23.2) ratios than the majority of arc basalts and andesites and relatively variable εNd(t) values (-1.54 to +3.02). The magnesian andesites are characterized by anomalously high MgO, Cr and Ni contents and have εNd(t) values of -3.90 to +1.17. The occurrence of adakitic rocks, Nb-enriched basalts and andesites and magnesian andesites has been described from many modern arcs featuring subduction of oceanic slab. Therefore, we suggest that similar mechanism may have played an important role in the production of the ~2.2Ga igneous rocks in the Lu¨liang Complex and thus the final collision between the Eastern and Western Blocks along the TNCO must have happened at some time after ~2.2Ga. © 2014 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 | 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.


Zhang J.,Chinese Academy of Geological Sciences | Yu S.,Chinese Academy of Geological Sciences | Gong J.,Chinese Academy of Geological Sciences | Li H.,Tianjin Institute of Geology and Mineral Resources | Hou K.,Chinese Academy of Geological Sciences
Precambrian Research | Year: 2013

The Dunhuang block, in the easternmost segment of the Tarim craton, exposes Precambrian mafic granulite and felsic gneiss. To better understand the poorly known formation and evolution of the Tarim craton, we carried out detailed field-based petrological and geochronological investigations on the major lithologies of the Dunhuang block. U-Pb dating and Hf isotopic analyses on the mafic granulite and felsic gneiss (TTG gneiss) of the Dunhuang block reveal two distinct age populations: the Latest Neoarchaean (∼2.5. Ga) and the Late Palaeoproterozoic (1.82-1.85. Ga). The zircon magmatic cores and metamorphic rims of tonalitic gneisses yield similar ages of ∼2.5. Ga, supporting the existence of Archean rocks in the Dunhuang block. The short time interval between Latest Neoarchean magmatism and high-grade metamorphism suggests that they were related to the same Latest Neoarchean tectonothermal event. The ∼2.5. Ga zircons show Hf-depleted mantle model ages between 2.55. Ga and 2.8. Ga with a peak at ∼2.7. Ga, suggesting that ∼2.7. Ga juvenile crust of the Dunhuang block was reworked during a 200-300. m.y. period at the end of the Neoarchean. The age of ∼1.85. Ga obtained from the mafic granulites and felsic gneisses is interpreted as the age of high-pressure granulite facies metamorphism. Combined with the Hf isotopic data, these data suggest that the Dunhuang block experienced ∼2.7. Ga crustal growth, a ∼2.5. Ga magmatic-metamorphic event and a 1.82-1.85. Ga (HP) granulite facies metamorphic event. This sequence of events is very similar to that of the North China Craton, implying that the evolutionary history of the Dunhuang block was consistent with that of the North China Craton from the Neoarchean to Paleoproterozoic. © 2012 Elsevier B.V.


Zhang J.,Chinese Academy of Geological Sciences | Gong J.,Chinese Academy of Geological Sciences | Yu S.,Chinese Academy of Geological Sciences | Li H.,Tianjin Institute of Geology and Mineral Resources | Hou K.,Chinese Academy of Geological Sciences
Precambrian Research | Year: 2013

The Alxa block was traditionally considered to be part of the North China Craton, but its metamorphic basement has been poorly studied. Here we present a systematic zircon U-Pb and Hf isotopic investigation on four orthogneiss samples in the Beidashan area of the western Alxa block. The petrographic and geochemical data show that these rocks are granodioritic and trondhjemitic gneisses with TTG (tonalite-trondhjemite-granodiorite) characteristics. Zircons from the TTG gneisses display typical core-rim or core-mantle-rim structures. U-Pb datings and Hf isotopic analyses reveal two distinct age populations: the Latest Neoarchean (~2.5Ga) and the Late Palaeoproterozoic (~1.85Ga). The magmatic zircon cores and metamorphic mantles (rims) of the TTG gneisses were dated at similar ages around 2.5Ga, supporting the existence of Archean rocks in the western Alxa block. The short time interval between the Latest Neoarchean magmatism and the subsequent metamorphism suggests that they were related to the same Latest Neoarchean tectonothermal event. The ~2.5Ga zircons have e{open}Hf(t) mainly between 0.8 and 5.0, TDM (Hf) model ages mainly between 2.6 and 2.8Ga (with a peak at ~2.7Ga) and TDMC (Hf) model ages mainly between 2.7 and 3.0Ga (with a peak at ~2.8Ga). The age of ~1.85Ga obtained from two trondhjemitic gneisses is interpreted as the age of the Late Paleoproterzoic high-grade metamorphism. Our combined datasets show that the TTG gneisses in the Baidashan area of the western Alxa block experienced a main 2.7-2.8Ga crust growth, a ~2.5Ga magmatic-metamorphic event and a ~1.85Ga high-grade metamorphic event. The sequence of events is very similar to that of the other North China Craton. A Combination of the data of Paleoproterozoic metamorphic rocks in the Alxa block suggests that the Alxa block is the western extension of the Khondalite Belt rather than the Yinshan block. © 2013 Elsevier B.V.

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