Time filter

Source Type

Nanchang, China

Zhang W.,Research Institute No270
Geotectonica et Metallogenia | Year: 2015

Morphology of orebody which describing its shape and internal structure and formation mechanism are important information for mining, researches for the ore genesis, and further geological exploration. The Xiangshan uranium ore field is the largest uranium deposit hosted in volcanic rocks in China. The hosting volcanic complex includes rhyodacite, porphyroclastic lava and late stage sub-volcanic rocks. The orebody form is mainly irregular vein-type and tubular structure. Field investigation and laboratory research show that the high-grade ores are in the forms of breccia and mylonitic structure, while the changes between the ores and the altered wall rock are abrupt, and no marks of faulting were observed. Moreover, the shape of the ore body and its internal structure show no genetic relationship with the territorial stress rupture structure, but present a kind of orebody morphology characteristics related to hydraulic crack structure. Tubular ore body is controlled by the crypto explosive initial fluidization breccia pipe, while vein ore body is shaped by two genetic types with one formed as ore-controlling structure influenced by the altered rock, and the other by the fluid breccia dike and the altered rocks. The present research shows that, in the Xiangshan field, ore-forming structure shaped by fluid breccia and hydrothermally altered rocks constitute the main minerogenetic forms. © 2015, Science Press. All right reserved. Source

Wang Z.,China University of Geosciences | LU G.,Chinese Academy of Geological Sciences | Xu P.,Research Institute No270 | Yang R.,China University of Geosciences | And 5 more authors.
Earth Science Frontiers | Year: 2015

The Nannihu orefield in the integrated exploration area of Western Henan is the largest at present molybdenum mine in China, which is a porphyry-skarn molybdenum deposit, and to which extensive systematic geological studies have been made. But, how to determine in the field the geological characterics of the minerogenetic series or metallogenetic system of the porphyry-skarn molybdenum deposit? And how to distinguish through geological survey the metallogenetic rock series from the metamorphic country rocks of Luanchuan group? These are the vital issues both in regional geological mineral exploration and in the peripheral prospecting and the exploration of deep-seated deposits in the Nannihu Mo-W orefield. This paper researches the Mesozoic granite ore-forming geological event in Western Henan. Based on the porphyry-skarn molybdenum deposit model, the petrological and mineralogical discriminant criteria of the ore-forming geological body are established. And the structural alteration mineral mapping of the Nannihu orefield has been conducted. On the basis of the 9 structure-alteration-petrofacies sections we established the structure-alteration-petrofacies zonation and completed the structure petrofacies mapping of the 1:10000 Nannihu orefield in the range of 6 square kilometers. We discriminated the contact metamorphism of Nannihu rock into thermal contact metamorphism and hydrothermal metamorphism. According to the temperature typomorphic minerals the thermal contact metamorphism can be subdivided into wollastonite hornfels zone, garnet hornfels zone and carbonate hornfels zone. According to the degree of alteration hydrothermal metamorphism is divided into skarn zone, skarn alteration zone and weak skarn alteration zone. Mapping results revealed the distribution of altered rocks. Thermal contact metamorphic belt developed extensively in the south of Nannihu-Sandaozhuang mine. It shows zonal distribution including wollastonite hornfels zone, garnet hornfels zone and carbonate hornfels zone; obviously it is controlled by the lithology of the country rock. Hydrothermal alteration metamorphic belt focuses on the north of Nannihu-Sandaozhuang mine and from east westwards in the order of skarn zone, skarn alteration zone and weak skarn alteration zone. In the south of Nannihu-Sandaozhuang mine the country rocks are carbonate rocks; and in the north of Nannihu-Sandaozhuang mine argillaceous volcanic rocks are dominant. This is the main factor controlling the distribution and development scale of these two types of altered rocks. This research presents a new way of thinking and the actual mapping results of regional mineral survey. It provides a typical study for the basic geological research connecting with the production practice in the geological prospecting, which is of theoretical significance and prospecting value. ©, 2015, Chinese Academy of Forestry. All right reserved. Source

Xu P.,Research Institute No270 | LU G.,Chinese Academy of Geological Sciences | Zhang Y.,China Energy Ltd | Zhou M.,No6 Exploration Institute Of Geology And Mineral Resources | And 7 more authors.
Earth Science Frontiers | Year: 2015

“Jiaojia type” gold deposits, such as Jiaojia, Xincheng, Sizhuang, etc. They are related with brittle-ductile deformation resulting from tectonics. However the research of brittle-ductile deformation needs to be strengthened at present, especially in terms of quantitative measurement and analysis. The paper studies a drilling core more than 1800 m passing through Jiaojia fault belt, in order to analyze and observe the altered granite in the footwall of the fault. The mineralogical and petrological studies of the samples revealed that the altered belt are composed of beresite-cataclasite zone, strong potash feldspathization zone, weak potash feldspathization zone, and non-altered granite zone. The beresite-cataclasite zone is dominated by brittle deformation with strong alteration and mineralization, whose bandwidth, total deformation quantity and ductile/brittle deformation ratio are 35.7 m, 75%-85% and 0.07 respectively. The strong potash feldspathization zone is characterized by ductile-brittle deformation with weaker alteration and mineralization, whose bandwidth, total deformation quantity and ductile/brittle deformation ratio are 10.6 m, 75%-80% and 0.78 respectively. Weak potash feldspathization zone is dominated by ductile deformation with subtle alteration and mineralization, whose bandwidth, total deformation quantity and ductile/brittle deformation ratio are 76.92 m, 45%-55% and 1.75 respectively. Overall, The major fracture mostly show brittle deformation, and far away from it mainly ductile deformation. The Au-mineralization mainly occurred in the transitional zone between brittle deformation and ductile-brittle deformation, in which beresitic cataclasite and strong potash feldspathization zones are located. ©, 2015, Chinese Academy of Forestry. All right reserved. Source

Chen Z.-L.,Chinese Academy of Geological Sciences | Yang N.,Chinese Academy of Geological Sciences | Wang P.-A.,Chinese Academy of Geological Sciences | Gong H.-L.,Chinese Academy of Geological Sciences | And 6 more authors.
Geological Bulletin of China | Year: 2011

The Xiangshan uranium ore-field is the largest volcanic-related meso-epithermal deposit in China and the uranium-mineralization is tightly controlled by fault activities. As exploited and doveloped for many years, the ore-reserve resource of the deposit is in current crisis, although the potential reservoir is probably great. Therefore, the study in ore-field structures is imminent to provide scientific guidance for ore-prospecting in the deep and surrounding areas. This paper mainly presents field measurement results of joints and fault scratches to identify features of tectonic activities and the principal stress direction, using traditional and modern methods in tectonic stress field research. Stages and times of the tectonic stress field are also determined based on successively superimposed deformation relations and diagenesis ages of volcanic rocks. The result showed that the tectonic stress field in the Xiangshan ore field can be divided into three stages and six periods. Basement deformation and two phases of volcanic activities occurred before the metallogensis, and main mineralization stages could be divided into three periods, and uranium ore bodies were locally dislocated by fault activities after the formation of ore-deposits. Characteristics of different phases of tectonic activities and its relationship to the uranium mineralization were additionally discussed, suggesting that the uranium mineralization was consistent with the evolution of the regional tectonic stress field. Favorable structural ore-forming areas for grade-rich ore-bodies in the Xiangshan uranium ore-field were further pointed out. Source

Chen Z.-L.,Chinese Academy of Geological Sciences | Wang Y.,Chinese Academy of Geological Sciences | Zhou Y.-G.,Chinese Academy of Geological Sciences | Han F.-B.,Chinese Academy of Geological Sciences | And 5 more authors.
Geology in China | Year: 2013

The volcanic-intrusive complexes were dated by the SHRIMP U-Pb dating method of zircons from the Xiangshan uranium orefield, Jiangxi Province. SHRIMP U-Pb dating of zircons from 7 volcanic rocks yielded 206Pb/238U concordant ages from 133Ma to 142Ma. The weighted mean ages of two porphyroclastic lava samples are 134.6±1.0Ma (MSWD=1.5) and 134.1±1.0Ma (MSWD=0.65), respectively, which constrain the latest volcanic eruption in Xiangshan area at 134Ma. Two sub-porphyritic granites from Baquan in northern and Wuzhang in southern Xiangshan uranium orefield have ages of 133.3±0.8Ma (MSWD=0.82) and 134.7±0.9Ma (MSWD=1.08). The consistent ages of granite porphyry with porphyroclastic lava within the error range indicate that these two types of rocks were approximately simultaneously erupted or/and then intruded, probably with similar origins, as also supported by field evidence and previous geochemical analyses. A rhyodacite sample obtained from drill hole No.ZK111A-1 in the upper part of the Daguding Formation at Shutang in western Xiangshan has age of 141.6±1.7Ma (MSWD=0.9), suggesting that the first-cycle of the volcanic eruption should have ended at about 142Ma, most probably during the Late Jurassic. The intrusive age of a quartz-monzonite granite-porphyry sample from drill hole No. ZK19-2 in Gangshangying area is 136.4±1.0Ma (MSWD=1.7), and the age of rhyodacite-porphyry from the Ruyiting section is 137.4±1.7Ma (MSWD=1.11), indicating an interval age of 136-137Ma between the first and the second cycle of volcanic eruption, and both the granite-porphyry and the rhyodacite -porphyry intruded during the interval time of two volcanic movement cycles. The dating results obtained by the authors and the previous researchers show that the second-cycle of the volcanic-intrusive movement in Xiangshan area ranged from 136Ma to 133Ma in time, belonging to early Cretaceous volcanic event. It is also proposed that the Ehuling Formation in Xiangshan area should be Early Cretaceous in age. Source

Discover hidden collaborations