Xie G.,Chinese Academy of Geological Sciences |
Mao J.,Chinese Academy of Geological Sciences |
Xiongwei L.,Geological Survey of Hubei Province |
Duan C.,China University of Geosciences |
Yao L.,China University of Geosciences
Lithos | Year: 2011
Late Mesozoic intrusive and volcanic rocks are widespread in the southeast Hubei Province, Middle-Lower Yangtze River Belt (YRB), East China. Detailed in situ zircon U-Pb and Hf isotope, elemental and Sr-Nd-Pb isotopic data are presented in this paper for Late Mesozoic volcanic rocks from the Jinniu Basin, YRB, aiming to constrain their age, petrogenesis, and tectonic implications. The Jinniu volcanic rocks show a bimodal distribution in composition, with dominant rhyolite and dacite, and subordinate basalt and basaltic andesite. New SHRIMP and LA-ICPMS zircon U-Pb ages indicate that the volcanic rocks of three Formations in the Jinniu basin were erupted at quite a short age range of about 5Ma during the Early Cretaceous (130-125Ma). The mafic rocks are moderately enriched in large-ion-lithophile-elements (LILE) (e.g., Ba, Th, U, and Pb) and light rare-earth-elements (LREE), and are characterized by negative Nb, Ta, and Ti anomalies, and relatively high TiO2 (0.72-2.06%) and Nb (9.20-26.5ppm) contents. These analyses indicate that the geochemical characteristics of the mafic rocks in the Jinniu basin are similar to worldwide Phanerozoic Nb-enriched basalt and andesites (NEBA). New in situ zircon U-Pb ages and field geological relationships demonstrate that NEBA in the southeast Hubei Province are not spatially or temporally associated with high-silica adakitic rocks, but were most likely derived from an enriched lithospheric mantle with assimilation of minor crustal materials, and then fractional crystallization during the evolution of the magma. Overall, the felsic rocks in the Jinniu basin have geochemical characteristics, and Sr-Nd-Pb signatures, and in situ zircon Hf isotopic compositions similar to those of the mafic rocks. Compared with the mafic rocks, the felsic rocks are characterized by enriched and variable concentrations of LILE and REE (e.g., Ba=33.3-1372ppm, Y=11.4-33.6ppm, YbC=5.07-18.7), and negative Eu anomalies (δEu=0.22-0.98), as well as a wide range of radiogenic Nd-Pb isotopic values with εNd (t)=-10.2 to -2.4, (206Pb/204Pb)i=17.659-18.705, (207Pb/204Pb)i=15.478-15.663, and (208Pb/204Pb)i=37.654-38.935, and in situ zircon Hf compositions of εHf (t)=-12.7 to -1.8. These features indicate that the genesis of felsic magma in the Jinniu basin is consistent with extensive fractional crystallization and large amounts of crustal contamination from an evolved mafic magma (SiO2=~55%). The bimodal volcanic rocks in this study provide convincing evidence that Early Cretaceous volcanic rocks in the YRB developed in a back-arc extensional tectonic regime. © 2011 Elsevier B.V.
Huang H.,China University of Geosciences |
Zhang Z.,China University of Geosciences |
Kusky T.,Wuhan University |
Santosh M.,China University of Geosciences |
And 4 more authors.
Lithos | Year: 2012
The South Tianshan Collisional Belt (STCB) and northern margin of the Tarim Block (NTB) are key areas for understanding the prolonged tectonic evolution of the Central Asian Orogenic Belt (CAOB). The Halajun region in Xinjiang province, NW China is located within the tectonic transition zone between STCB and Tarim Blocks. Several granitic intrusions and one mafic-ultramafic complex (Piqiang complex) are exposed in this region. Zircon U-Pb dating, whole-rock major oxide, trace element and Nd isotopic data are presented for the Huoshibulake, Tamu, Kezi'ertuo and Halajun II granitic intrusions in this area. New LA-ICP-MS U-Pb age for Kezi'ertuo intrusion, coupled with previously published SHIRMP U-Pb ages for Huoshibulake and Halajun II intrusions and Piqiang complex, reveals that all the igneous rocks in the Halajun region are coeval (~275Ma). Geochemically, the four granitic intrusions show high contents of SiO2, K2O and total alkalis and possess trace element patterns characterized by Rb, Nb, Ta, Zr and Hf enrichment and significantly negative Ba, Sr, P, Eu and Ti anomalies. These features strongly favor an A1-type affinity for the Halajun granitic intrusions. Among the four intrusions, the Kezi'ertuo, Tamu and Halajun II intrusions possess positive to slightly negative εNd(t) values ranging from -0.9 to +0.6, whereas the Huoshibulake intrusion displays less depleted εNd(t) values of -2.6 to -2.9. Our new elemental and isotopic data suggest that the four granitic intrusions were generated by the partial melting of a common Neoproterozoic gabbroic source, probably as a result of the ~275Ma underplating of the asthenosphere mantle-derived magmas. The variable involvement of the mantle components accounts for the range of εNd(t) values. After the generation of the parental magma, alkali feldspar, arfvedsonite, biotite, Fe-Ti oxides and zircon seem to have fractionated prior to the final emplacement of the granitic magmas. In combination with the regional geological history, we propose that the ~275Ma A1-type granitic magmatism in the Halajun region and other areas of the NTB provides a good proxy record for the vertical continental crustal growth in the southern margin of the CAOB during the Permian. Our study, in combination with other geological evidence, indicates that these A1-type felsic and OIB-like mafic-ultramafic rocks, with ages from ~282Ma to ~275Ma, in the southern margin of the CAOB are parts of the Permian Tarim large igneous province and could be genetically related to the Tarim mantle plume. © 2012 Elsevier B.V.
Wang G.-G.,Nanjing University |
Ni P.,Nanjing University |
Yu W.,Nanjing University |
Chen H.,Nanjing University |
And 4 more authors.
Lithos | Year: 2014
The Shapinggou molybdenum deposit is located in the Qinling-Tongbai-Hong'an-Dabie Orogen, which accommodates the largest molybdenum ore belt in the world. New laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb dating, geochemical and Sr-Nd-Hf isotope data for the granitoids at Shapinggou are presented in this paper. Two stages of Early Cretaceous magmatism, 138-128Ma and 116-114Ma, took place at Shapinggou in a post-collisional setting. These granitoids can be divided into four groups, including the early-stage granites (134-129Ma, SiO2=62.33 to 76.27%) and intermediate rocks (129-128Ma, SiO2=52.41 to 60.72%) and the late-stage quartz syenite (116Ma, SiO2=64.09 to 65.12%) and Mo-bearing granite porphyry (114Ma, SiO2=74.95 to 77.26%). The early-stage granites have high Sr contents, Sr/Y and LaN/YbN ratios, but low Y, Yb and MgO contents, showing low-Mg adakitic chemical features. They were possibly generated by partial melting of the thickened mafic lower continental crust. The early-stage intermediate rocks have relatively high MgO contents (2.71 to 4.84%) and Mg# values (46 to 60), but low Sr/Y and LaN/YbN ratios, which were likely derived from a hybrid mantle metasomatized by melts from foundered eclogitic lower continental crust and subsequent fractional crystallization. The late-stage quartz syenite shows chemical features of metaluminous A-type granites, including high abundances of alkalis, HFSE (Zr, Nb), and trivalent REE. The late-stage Mo-bearing granite porphyry displays high SiO2, alkalis, Zr, Ce contents, and A/CNK ratios, but low Ba, Sr, P and Ti, showing affinity to highly fractionated I-type granites. The late-stage quartz syenite and granite porphyry were possibly produced by partial melting of intermediate compositions of middle crust. Our results support the conclusion that there were three-layer continental crusts in the Dabie Orogen prior to Early Cretaceous magmatism and suggest that post-collisional granitoids in the Dabie Orogen were derived from not only lower crust but also middle crust. The giant Shapinggou porphyry Mo deposit was most likely formed by effective transport of volatiles and Mo in a convecting granitic magma column, rather than by direct melting of Mo-enriched sources. The Mo-bearing rocks at Shapinggou are characterized by a high degree of magma differentiation, close associations with A-type granite, and formation at the end of regional magmatism. © 2013 Elsevier B.V.
Huang J.,Hefei University of Technology |
Xiao Y.,Hefei University of Technology |
Gao Y.,University of Houston |
Hou Z.,Hefei University of Technology |
Wu W.,Geological Survey of Hubei Province
Journal of Metamorphic Geology | Year: 2012
Niobium and Ta concentrations in ultrahigh-pressure (UHP) eclogites and rutile from these eclogites and associated high pressure (HP) veins were used to study the behaviour of Nb-Ta during dehydration and fluid-rock interaction. Samples were collected through a ~2km profile at the Bixiling complex in the Dabie orogenic belt, Central-Eastern China. All but one eclogite away from veins (EAVs) display nearly constant Nb/Ta ratios ranging from 16.1 to 19.2, with an average of 16.9±0.8 (2 SE), similar to that of their gabbroic protolith from the Yangtze Block. Nb/Ta ratios of rutile from the EAVs range from 12.7 to 25.3 among different individual grains, with the average values close to those of the corresponding bulk rocks. These observations show that Nb and Ta were not significantly fractionated by prograde metamorphism up to eclogite facies when no significant fluid-rock interaction occurs. In contrast, Nb/Ta ratios of rutile from eclogites close to veins (ECVs) are highly variable from 17.8 to 49.8, which are systematically higher (by up to 17) than those of rutile from the veins. These observations demonstrate that Nb and Ta were mobilized and fractionated during localized fluid flow and intensive fluid-rock interaction. This is strongly supported by Nb/Ta zoning patterns in single rutile grains revealed by in situ LA-ICP-MS analysis. Ratios of Nb/Ta in the ECV-hosted rutile decrease gradually from cores towards rims, whereas those in the EAV-hosted rutile are nearly invariable. Furthermore, the vein rutile shows Nb/Ta zoning patterns that are complementary to those in rutile from their immediate hosts (ECVs), suggesting an internal origin for the vein-forming fluids. The Nb/Ta ratios of such fluids evolved from low values at the early stage of subduction to higher values at later supercritical conditions with increased temperature and pressure. Quantitative modelling was conducted to constrain the compositional evolution of metamorphic fluids during dehydration and fluid-rock interaction focusing on Nb-Ta distribution. The modelling results based on our proposed multistage fluid phase evolution path can essentially reproduce the natural observations reported in the present study. © 2012 Blackwell Publishing Ltd.
Zhou L.,Zhejiang University |
Zhang D.,Hangzhou Normal University |
Wang J.,Hangzhou Normal University |
Huang Z.,Geological Survey of Hubei Province |
Pan D.,State Oceanic Administration
Remote Sensing | Year: 2013
Coal fires have been found to be a serious problem worldwide in coal mining reserves. Coal fires burn valuable coal reserves and lead to severe environmental degradation of the region. Moreover, coal fires can result in massive surface displacements due to the reduction in volume of the burning coal and can cause thermal effects in the adjacent rock mass particularly cracks and fissures. The Wuda coalfield in Northern China is known for being an exclusive storehouse of prime coking coal as well as for being the site of occurrence of the maximum number of known coal fires among all the coalfields in China and worldwide, and is chosen as our study area. In this study, we have investigated the capabilities and limitations of ALOS PALSAR data for monitoring the land subsidence that accompanies coal fires by means of satellite differential interferometric synthetic aperture radar (DInSAR) observations. An approach to map the large and highly non-linear subsidence based on a small number of SAR images was applied to the Wuda coalfield to reveal the spatial and temporal signals of land subsidence in areas affected by coal fires. The DInSAR results agree well with coal fire data obtained from field investigations and thermal anomaly information, which demonstrates that the capability of ALOS PALSAR data and the proposed approach have remarkable potential to detect this land subsidence of interest. In addition, our results also provide a spatial extent and temporal evolution of the land subsidence behavior accompanying the coal fires, which indicated that several coal fire zones suffer accelerated ongoing land subsidence, whilst other coal fire zones are newly subsiding areas arising from coal fires in the period of development. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
Shi D.,Chinese Academy of Geological Sciences |
Lu Q.,Chinese Academy of Geological Sciences |
Xu W.,Chinese Academy of Geological Sciences |
Yan J.,Chinese Academy of Geological Sciences |
And 3 more authors.
Tectonophysics | Year: 2013
To understand the formation and the tectonic process of the Mesozoic middle-lower Yangtze metallogenic belt (YMB), the SinoProbe program deployed a quasi-linear passive source seismic array across the belt. We performed receiver function profiling and measurement of shear-wave splitting parameters with the collected data. Our results show that the Moho depth varies significantly along the profile and that a "mantle uplift" exists right beneath the YMB. We also found that the lower crust of the YMB is different from that of its adjacent areas in structure on the receiver function profile. It possesses seismic anisotropy with direction roughly parallel to the belt. Our SKS/SKKS shear-wave splitting results also show similar belt-parallel azimuthal anisotropy right beneath the YMB. We interpret the seismic anisotropy in the lower crust of the YMB as the result of mineral crystal alignment caused by melting and belt-parallel flow in the Mesozoic ore-forming process. Besides, we observed a nearly south-dipping converter extending from shallow to lower crust beneath the Hefei Basin, which most possibly resulted from the Mesozoic crustal extension. We interpret the "mantle uplift" and the crustal extensional structures to be consequences of asthenospheric upwelling during the Mesozoic ore-forming process. Our results suggest that the lower crust of the YMB was most likely one part of the multi-level metallogenic magma system in the Mesozoic magmatism and mineralization processes, and the formation of the metallogenic belt to be a result much similar to the MASH (Melting, Assimilation, Storage and Homogenization; cf. Hildreth and Moorbath, 1988; Richards, 2003) process. First, the asthenospheric upwelling resulted in a crustal extensional environment; then the melts from the upwelling asthenosphere intruded into the lower crust of the YMB, and assimilation occurred when they mixed with in situ lower crustal materials, which led to the formation of adakitic-like magma; the adakitic-like magma rose up along extensional structures, and reacted with country rocks to form mineral deposits. © 2013 Elsevier B.V.
Li C.,CAS Institute of Vertebrate Paleontology and Paleoanthropology |
Rieppel O.,Field Museum |
Wu X.-C.,Canadian Museum of Nature |
Zhao L.-J.,Zhejiang Museum of Nature History |
Wang L.-T.,Geological Survey of Hubei Province
Journal of Vertebrate Paleontology | Year: 2011
A new genus and species of marine reptile is described from the Pelsonian (Anisian, Middle Triassic) of Luoping County, Yunnan Province, southwestern China. This diapsid reptile with a secondarily closed upper temporal fossa is the sister taxon to Saurosphargis from the lower Muschelkalk (Anisian, Middle Triassic) of central Europe. It further emphasizes the close faunal affinities between the Eastern and Western Tethyan realm. The new taxon is convergent on cyamodontoid placodonts in having developed a dorsal body armor composed of small osteoderms. The underlying ribs are transversely broadened so as to establish contact along their length, thus forming a closed dorsal 'rib basket,' a unique morphology shared with Saurosphargis. © 2011 by the Society of Vertebrate Paleontology.
Jin Z.,CAS Institute of Earth Environment |
Jin Z.,Xi'an Jiaotong University |
Li X.,Hong Kong Polytechnic University |
Zhang B.,Geological Survey of Hubei Province |
And 2 more authors.
Quaternary International | Year: 2013
Daihai Lake is located in a hydrologically closed basin within the transitional zone of the East Asian monsoon, which has experienced significant lake-level fluctuations. The sedimentary sequence of a 12.08m core was analyzed for mobile (Ca, Mg, and Sr) and immobile elements (Al and Fe) and trace metals (e.g., Co, Ni, Cu, Zn, and Pb) in order to study the changes of natural chemical compositions and the potential influences of the historical mining and use of metals during the Holocene period. Climate changes have a significant influence on the concentrations of mobile elements in the Holocene lake sediment; high concentrations occurred during the times with high lake level, resulting from enhanced catchment weathering due to strong monsoon effects. Different from these mobile elements, the variation of immobile elements and trace metals in Daihai Lake sediment shows clear anthropogenic impact of the mining and use of metals in the last several millenniums. A gradual increase in the concentrations and fluxes of metals from ~5000 cal. a B.P. is correlated well with the emergence of Chinese civilization. The concentrations and fluxes of these metals and immobile elements in the sediments increased rapidly between 2100 and 1250cal. a B.P., indicating the extensive use of metals during the Warring States Period (475-221B.C.), and the early Han Dynasty (206B.C.-220A.D.). Further increase of trace metals, such as Cu, Ni, Co, and Pb, after the Medieval Warm Period (1200-800aB.P.) likely reflects the increased metal emissions associated with extensive mining and utilization activities. Similar patterns of sedimentary metals between Daihai Lake in northern China and Liangzhi Lake in central China further indicate significant environmental impacts of the mining and utilization of metals in the progress of Chinese civilization in the past several thousand years. © 2013 Elsevier Ltd and INQUA.
Liu W.,Hubei University |
Liu W.,Geological Survey of Hubei Province |
Zhang J.,Hubei University |
Sun T.,Geological Survey of Hubei Province |
Wang J.,Hubei University
Journal of Geochemical Exploration | Year: 2014
The Cretaceous Luzong and Ningwu volcanic basins in eastern China contain numerous magnetite-apatite deposits with similar geological characteristics and mineralization ages (~. 130. Ma). These deposits, however, occur at distinctly different burial depths. To explain this difference, LA-ICP-MS apatite U-Pb and fission track double dating of five samples were carried out to establish the thermal histories from crystallization to the exhumation of four representative deposits: the deeply buried Nihe (665-1065. m underground) and Luohe deposits (425-856. m underground) from the Luzong basin; the shallow Meishan deposit (40-530. m underground) and the exposed Dongshan deposit from the Ningwu basin. The cooling histories of the four deposits could be divided into rapid cooling for the Dongshan deposit and slow continuous cooling for the Nihe, Luohe, and Meishan deposits. Combined with geological evidence, it can be determined that the Dongshan and Meishan deposits formed at shallow depths with the Dongshan deposit emplaced at a very high level while the Meishan deposit was emplaced relatively deeper. The Nihe and Luohe deposits were emplaced deeper than the Dongshan and Meishan deposits and the burying of the Shuangmiao volcanic cycle after mineralization increased the burial depth. However, this burial event did not occur in the Ningwu basin. All of these resulted in the different burial of the magnetite-apatite deposits between the two basins prior to 120. Ma while the exhumation after 120. Ma among these deposits was similarly slow and continuous. The metallogenic conditions of both basins were similar but the smaller number and gross reserve of magnetite-apatite deposits in the Luzong basin, we believe that the Luzong basin has better preservation potential for the magnetite-apatite deposits. © 2013 Elsevier B.V.
Ni P.,Nanjing University |
Wang G.-G.,Nanjing University |
Yu W.,Nanjing University |
Chen H.,Nanjing University |
And 4 more authors.
Ore Geology Reviews | Year: 2015
The Shapinggou porphyry Mo deposit, one of the largest Mo deposits in Asia, is located in the Dabie Orogen, Central China. Hydrothermal alteration and mineralization at Shapinggou can be divided into four stages, i.e., stage 1 ore-barren quartz veins with intense silicification, followed by stage 2 quartz-molybdenite veins associated with potassic alteration, stage 3 quartz-polymetallic sulfide veins related to phyllic alteration, and stage 4 ore-barren quartz±calcite±pyrite veins with weak propylitization. Hydrothermal quartz mainly contains three types of fluid inclusions, namely, two-phase liquid-rich (type I), two- or three-phase gas-rich CO2-bearing (type II) and halite-bearing (type III) inclusions. The last two types of fluid inclusions are absent in stages 1 and 4. Type I inclusions in the silicic zone (stage 1) display homogenization temperatures of 340 to 550°C, with salinities of 7.9-16.9wt.% NaCl equivalent. Type II and coexisting type III inclusions in the potassic zone (stage 2), which hosts the main Mo orebodies, have homogenization temperatures of 240-440°C and 240-450°C, with salinities of 34.1-50.9 and 0.1-7.4wt.% NaCl equivalent, respectively. Type II and coexisting type III inclusions in the phyllic zone (stage 3) display homogenization temperatures of 250-345°C and 220-315°C, with salinities of 0.2-6.5 and 32.9-39.3wt.% NaCl equivalent, respectively. Type I inclusions in the propylitization zone (stage 4) display homogenization temperatures of 170 to 330°C, with salinities lower than 6.5wt.% NaCl equivalent. The abundant CO2-rich and coexisting halite-bearing fluid inclusion assemblages in the potassic and phyllic zones highlight the significance of intensive fluid boiling of a NaCl-CO2-H2O system in deep environments (up to 2.3kbar) for giant porphyry Mo mineralization. Hydrogen and oxygen isotopic compositions indicate that ore-fluids were gradually evolved from magmatic to meteoric in origin. Sulfur and lead isotopes suggest that the ore-forming materials at Shapinggou are magmatic in origin. Re-Os dating of molybdenite gives a well-defined 187Re/187Os isochron with an age of 112.7±1.8Ma, suggesting a post-collisional setting. © 2014 Elsevier B.V.