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Jia R.-X.,Chinese Academy of science | Jia R.-X.,Beijing Exploration Technology Center for Mineral Resources | Jia R.-X.,Beijing Donia Resources Co. | Fang W.-X.,Chinese Academy of science | And 2 more authors.
Kuangwu Yanshi/ Journal of Mineralogy and Petrology | Year: 2011

The NM deposit is located in the northwest trending magmatic-tectonic belt, northcentral part of Truong Son, which was subjected to right-lateral shearing due to the collision of Sibumasu micro-continent with Indo-China micro-continent along Nan-Uttaradit suture during Permian-Triassic Period. Based on the grain size and spatial distribution,the granites in NM deposit can be classified into medium-coarse grained granite, porphyritic granite and fine grained granite respectively. The geochemical characteristics of different types of granite show that they are high-potassium, calc-alkaline granitoids with the ACNK ratios mostly ranging from 0.9 to 1. 1. Trace elements of the granites show that the variety of LILE enriches in Cs, Rb, Th, U,K, while depletes in Ba and Sr,distinct fractionation of HFSE with clearly negative anomaly of Nb,P and Ti. REE analysis reveals relative high content and distinct fractionation of LREE in contrast to HREE,and moderate to sharp negative Eu anomaly. All of the geochemical features indicate that these different types of granites in NM deposit were derived from the same origin related to the special tectonic setting of post-collision volcanic arc. During the magmatic evolution process from early stage represented by medium-coarse grained granite to last stage represented by fine grained granite, the TFe, TiO 2, MgO 1CaO and Na 2O contents in magma tend to decrease, while the SiO 2 and K 2O contents increase gradually, and the Fe,Cu and Zn (Pb) mineralization is mainly related to the porphyritic granite. Source

Wang L.-Q.,Chinese Academy of Geological Sciences | Gu X.-X.,China University of Geosciences | Tang J.-X.,Chinese Academy of Geological Sciences | Wang H.,Chinese Academy of Geological Sciences | And 3 more authors.
Journal of Chengdu University of Technology (Science and Technology Edition) | Year: 2011

The paper studies the source and characteristics of the ore-forming fluids in the Mengya'a Pb-Zn deposit of Tibet and identifies the genetic type of deposit by studying the typical deposit of this area. It analyzes the altered limestone in the surrounding area, the carbon and oxygen isotopes of hydrothermal calcite and the hydrogen and oxygen isotopes of quartz formed in different mineralization periods, studies the fluid inclusions petrographically, and measures their temperatures and salinity. The resuct shows that in the early post-mineralization stage, the ore-forming fluids were was mainly in the form of magmatic water, while in the later stage, they were mixed with plentiful meteoric water. In the mineralization period, ore-forming fluids were generally characterized by medium-high temperatures and intermediate-low salinity and there was an apparent temperature-dropping trend from the early to the late ore-forming stage. The formation of the deposit is closely related to magmatism and the deposit is a zinc-lead one under the skarn type. Source

Han S.-L.,Central South University | Zhang S.-G.,Central South University | Liu J.-X.,Central South University | Hu H.-J.,Central South University | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2013

In mineral exploration, the apparent resistivity and apparent frequency (or apparent polarizability) parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method. © 2013 The Nonferrous Metals Society of China. Source

Han S.,University of South China | Han S.,Central South University | Zhang S.,Central South University | Liu J.,Central South University | And 3 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2014

There are pre-, syn-, and post-orogenic granites in Shire region of northern Ethiopia. Whole rock Sm-Nd isochron dating results show that diagenetic age of pre-, and post-orogenic ages are 824.4±15.5 Ma and 517.9±5.8 Ma respectively. Major, rare-earth and trace elements of three kinds of granite are obviously different. The pre-orogenic granites are relatively low in MgO and high in SiO2, belonging to the peraluminous series granite, with low K content and slight light REE enrichment, high large-ion lithophile element abundance and relative depletion of HFSE.The syn-orogenic granite belongs to the quasi-aluminous rock and high-potassium calc-alkaline granite, with the light REE enriched pattern, high large-ion lithophile element and HFSE abundances. The post-orogenic granite belongs to the weakly peraluminous high-potassium calc-alkaline granite, which has the chondrite-normalized REE patterns in the type of "gull" with severe depletion in Eu. The large-ion lithophile elements are concentrated, while P and Ti are severely depleted here. Comprehensive study shows both the pre- and syn-orogenic granites are I-type mantle-source granites in the passive continental margin-volcanic island arc tectonic setting; the post-orogenic granites are A2-type crust-source major granites, which were formed from the melting of thinner crust after the closure of oceanic basins and the growth of Arabian-Nubian shield. Source

Jia R.,Chinese Academy of science | Jia R.,Beijing Exploration Technology Center for Mineral Resources | Jia R.,Beijing Donia Resources Co. | Fang W.,Chinese Academy of science | And 2 more authors.
Journal of Rare Earths | Year: 2010

The NM copper polymetal deposit is located in the middle north part of the Truong Son metallogenic belt in Laos, which is the skarn-typed deposit and located in the contact between Indosinian granite and Lower Carboniferous limestone. All the ore-bodies in NM deposit can be divided into four types according to their occurrences: I copper ore-body as the massive restite developed in inner contact near the granite in north part; II-1 zinc-copper ore body and II-2 copper-iron ore body developed within contact between the granite and carbonate rocks, III copper-zinc ore body developed in the cranny among the southern carbonate stratum, indicating that all the ore-bodies were related to Indosinian granite emplacing into the Carboniferous limestone and causing the metallogenic system from closed state getting into half open state. The geochemical characteristics and mineral assemblages of them showed that all the orebodies in NM deposit derived from a similar origin and their ore-forming fluids with the evolution trend from reductive state in early stage to oxidative state in later stage were mainly related to the coupling interaction between post-magmatic hydrothermal fluid and basin fluid. Copyright © 2012 Elsevier B.V. Source

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