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Sun W.Y.,China University of Geosciences | Sun W.Y.,University of Tasmania | Li S.R.,China University of Geosciences | Santosh M.,China University of Geosciences | Zhang X.Y.,China Metallurgical Geology Bureau
Geological Journal | Year: 2015

The Yanjiagou deposit, located in the central North China Craton (NCC), is a newly found porphyry-type Mo deposit. The Mo mineralization here is spatially associated with the Mapeng batholith. In this study, we identify four stages of ore formation in this deposit: pyrite phyllic stage (I), quartz-pyrite stage (II), quartz-pyrite-molybdenite stage (III), which is the main mineralization stage, and quartz-carbonate stage (IV). We present sulphur and lead isotope data on pyrite, and rhenium and osmium isotopes of molybdenite from the porphyry deposit and evaluate the timing and origin of ore formation. The δ34S values of the pyrite range from -1.1‰ to -0.6‰, with an average of -0.875‰, suggesting origin from a mixture of magmatic/mantle sources and the basement rocks. The Pb isotope compositions of the pyrite show a range of 16.369 to 17.079 for 206Pb/204Pb, 15.201 to 15.355 for 207Pb/204Pb, and 36.696 to 37.380 for 208Pb/204Pb, indicating that the ore-forming materials were derived from a mixture of lower crust (or basement rocks) and mantle. Rhenium contents in molybdenite samples from the main ore stage are between 74.73 to 254.43ppm, with an average of 147.9ppm, indicating a mixed crustal-mantle source for the metal. Eight molybdenite separates yield model ages ranging from 124.17 to 130.80Ma and a mean model age of 128.46Ma. An isochron age of 126.7±1.1Ma (MSWD=2.1, initial 187Os=0.0032±0.0012ppb) is computed, which reveals a close link between the Mo mineralization and the magmatism that generated the Mapeng batholith. The age is close to the zircon U-Pb age of ca. 130Ma from the batholith reported in a recent study. The age is also consistent with the timing of mineralization in the Fuping ore cluster in the central NCC, as well as the peak time of lithosphere thinning and destruction of the NCC. We evaluate the spatio-temporal distribution of the Mo deposits in the NCC and identify three important molybdenum provinces along the northern and southern margins of the craton formed during three distinct episodes: Middle to Late Triassic (240-220Ma), Early Jurassic (190-175Ma), and Late Jurassic to Early Cretaceous (150-125Ma). The third period is considered to mark the most important metallogenic event, coinciding with the peak of lithosphere thinning and craton destruction in the NCC. © 2014 John Wiley & Sons, Ltd. Source

Zhang Z.-W.,China University of Geosciences | Zhang Z.-W.,Bureau of Mineral Resources | Li H.,Geophysical Exploration Academy of China Metallurgical Geology Bureau | Yu B.,Geophysical Exploration Academy of China Metallurgical Geology Bureau | Zhou S.-G.,China Metallurgical Geology Bureau
Applied Mechanics and Materials | Year: 2014

The Dayaoshan, which has nearly 200 gold deposits (or mineralization points), is one of the most important gold deposits distribution areas in Guangxi, and the Gupao gold deposit is an important representative one. Previous researches have carried out numerous works there to guide the gold prospecting work. Due to multiple episodes of gold mineralization and multiple sources materials in ore-forming, there are heated debates on the era of the mine, and the main mineralization age of the Gupao gold deposit is focused on the Caledonian or Early Yanshanian. According to the distribution characteristics of the gold ore body showing in the Zhilong, Gulinao, and Dawangding gold deposit, the discussion of macro-tectonic setting of the area, as well as the comparative study of surrounding gold deposits, we conclude that the main mineralization age of the Dawangding gold deposit is Early Yanshanian, and the main mineralization may be controlled by the nearly east-west trending fold which was caused by the north-south extrusion. © (2014) Trans Tech Publications, Switzerland. Source

Zhang B.,Central South University | Li X.,Central South University | Mao X.,Central South University | Deng H.,Central South University | Zhou S.,China Metallurgical Geology Bureau
International Conference on Geoinformatics | Year: 2016

On the basis of analysis of manganese metallogenesis conditions in the western Guangxi and southeastern Yunnan area, some geological variables, including sedimentary basins, synsedimentary faults, deposit facies, strata, lithology combinations, digital topographical features, aeromagnetic anomalies, etc., were built by spatial analysis methods of GIS field model. To solve the information asymmetry problem between prediction areas and known areas, this paper brought a method for mineral resources quantitative prediction limited by spatial extent of action, which matched metallogenesis conditions of prediction with prediction models built in known areas to ensure the information symmetry. To avoid subjectivity of evidence designation in the weights of evidence (WofE) method, linear regression analysis method was applied to filter the evidences. A method considering not only manganese deposits' number but also their quantities was taken to lower the information loss in the binary conversion of evidences. © 2015 IEEE. Source

Li W.-C.,China University of Geosciences | Liu X.-L.,China University of Geosciences | Zeng P.-S.,China Metallurgical Geology Bureau | Yin G.-H.,Yunnan Geological Survey
Geology in China | Year: 2011

The Pulang porphyry copper deposit is a typical Indo-Chinese porphyry copper deposit in Zhongdian area, hosted in southern composite body of the Yidun structural-magmatic belt. The composite rock body is a hypabyssal -ultrahypabyssal intermediate -acid porphyry (porphyrite) body, which can be divided into three invasion stages, i.e., quartz diorite porphyrite, quartz monzonite porphyry, and granodiorite-porphyry. Geochemical characteristics show that the rocks are enriched with Ba, La, Rb, Sr, K, chalcophile elements Cu, Pb, and siderophile elements Mo, Ni, and are depleted in Nb, Zr, Hf and Ti. Porphyry (porphyrite) is the same as the rock series of granite island, belonging to cale-alkaline suite, and their genetic types are also similar to each other, belonging to I-type granite. The ore bodies are controlled by structures. The porphyry copper deposit mainly occurs in the Indo -Chinese intermediate -acid porphyry (porphyrite), and the mineralization was controlled by such factors as magmatic rocks, emplacement formation, uranium migration, hydrothermal alteration and structural space, which joindy constituted a porphyry metallogenic system characterized by the structural-magmatic- hydrothermal coupling in Indo-Chinese period. Source

Liu X.,CAS Institute of Tibetan Plateau Research | Hsu K.J.,CAS Institute of Geology and Geophysics | Ju Y.,China Metallurgical Geology Bureau | Li G.,Chinese Academy of Geosciences | And 4 more authors.
Journal of Asian Earth Sciences | Year: 2012

We present a new interpretation of tectonic evolution in southern Tibet that is drastically different from the existing models. A detailed tectono-sedimentary study crossing the Yarlung Zangpo ophiolite zone shows that many geological features are different from those commonly described in large subduction collision models. For example, no N-S oriented shear zones are found between the ophiolitic sequence and country flysch strata, whereas a conformable contact relationship is recognized between them. A tectonic window exists inside the ophiolite body in the Bailang region. Some intrusion-like mafic-ultramafic bodies occurred in the Renbu region, where the country strata are in sub-concordant contact with these bodies and show contact metamorphic aureole. Toward the west, the ophiolite zone was separated by flysch sequences into sub-parallel branches. In the Lhasa region, the sedimentary facies are similar on both sides of the Zangpo Valley, and have preserved an intact Mesozoic basin system. Instead of ophiolite rocks, volcaniclastic deposits occurred in the corresponding location of the ophiolite in the Zangpo Valley. Consequently, we conclude that the Zangpo ophiolite zone has a tectonic affinity of back-arc basin with its spasmodic growth of juvenile oceanic crust. The real tectonic suture, or the closure zone of the Neotethys, should be represented by the High Himalaya Central Gneiss Unit, which shows a large scale strong shearing in same orientation, high metamorphism and protracted re-mobilization. The oceanic crust subducted northward and split off the Himalaya continental front arc, created the Zangpo back-arc basin since Late Triassic. The collapse of the Zangpo back-arc basin by supra-subduction occurred since the Eocene. The final collision between India and the Himalayan arc took place since Late Eocene with a re-mobilized large shear system. The major mylonitic zones migrated progressively southward with bulk of shear slip absorbing the crust of north India and south Tibet. © 2012 Elsevier Ltd. Source

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