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Li W.,Gansu Geology and Minerals Scientific Information Center | Liu J.,Gansu Provincial Bureau of Geology and Mineral Exploration and Development | Li T.,Geological Survey of Gansu Province | Jia Z.,Gansu Provincial Bureau of Geology and Mineral Exploration and Development
Northwestern Geology | Year: 2015

Au enrichment zone in Xiahe-Hezuo of Gansu Province is located in the west section of Qinling orogenic belt, where the geological condition is complicated, with major Outcropped strata including Carboniferous, Permian, Triassic and Paleogene. In Yanshanian and Indosinian, the intermediate-acid magma intrusive activity is intensive. The faults are mainly overthrust strikeslip faults, with occurrences of secondary fractures and interlayer fracture zones. 47 mineral spots were identified, among which there are 3 large-scale occurrences, 3 middle-scale and 41 small-scaledeposits, indicating great potential for prospecting. Based on the theories and method of geochemical blocks, the authors confirmed geochemical blocks of Au, Ag, Sb and anatomized its structure with GeoMDIS and geochemical data handling. Abnormity conversion from regional to local was studied, family tree of elements geochemistry was established, and the mineralization track of each sub-block was recovered. Results show that the high Au value area is large; blocks of each level concentrate significantly to form Au geochemical province, which is spatial overlaid and combined with Ag and Sb blocks. It is calculated that the total of light gold within 500 m is 1000 t, with the geochemical block characteristics of large and ultra-large gold deposit. The oreforming geological conditions in the study area is favorable; evaluation on Au resources potential has important significance for mineral resources evaluation and exploration.

Zhang X.-H.,Gansu Provincial Bureau of Geology and Mineral Exploration and Development | Feng J.,Geological Survey of Gansu Province | Yin Y.,Gansu Provincial Bureau of Geology and Mineral Exploration and Development | Sun J.-I.,Gansu Institute of Mineral Industry
Northwestern Geology | Year: 2012

Heishan Ni-Cu deposit is situated on the Heishan-Jiznquanzi Fault which is the south margin of Mazongshan middle block within Kazakhstan paleo-plate. The fault has the characteristics of marginal rift on the edge of paleo-plate, and regionally, the fault and rock mass appear the obvious gravity and magnetic anomaly. The ore-bearing rock body intruded into dolomite marble of Qingbaikou Series Dahui-oluoshan Group, and Cambrian Shuanyingshan Formation carbonaceous-siliceous-slate, metamor-feldspar-quartz-sandstone and baritic rock. Viewing from the surface, the body is the pear shape with the outcrop area of nearly 0. 25 km2, slightly longer on the NW direction, about 800 m long and 470 m wide. It is a complex massif developed from multi-intrusive of the same source and period, mainly comprised of plagio-harzburgite, hornblende-olivinite, olivine-hornblende-gabbro, and hornblende gabbro. The first phase is hornblende-gabbro facies which consist of hornblende-gabbro and quartz-syenite block within gabbro. The second phase is olivine-hornblende- gabbro and plagio-harzzburgite facies which consist of olivine-hornblende- gabbro, hornblende-olivine-gabbro, hornblende gabbro, and plagio-harzburgite. The average of chemical composition is similar with ultrabasic rock. The basicity index σ is very low, average is 0. 05, TiO20.28, m/f (Wu Liren) 4.79, Zavaritskiivalues 6 = 56. 00, 5 = 39.77; m' = 81. 68; Na 2O>K2O, the basicity type is Pacific type. The protomagma is characterized of olivine-tholeiite, came from the upper mantle. The average value of Mg/Fe is 4. 79. Ni-Cu orebody with appearance of len, vein and stratiform-like mainly exist the middle and lower part of rock mass. Mother rock and ore-bearing rock mainly consist of harzbeugite, secondly hornblende-gabbro. The ore body is classified into 3 types; insitu liquation, late period injection and contact metamorphic body. The ore minerals include niccolite, chloanthite, chalcopyrite, millerite, magnetic pyrite, chalcocite, as' well as some pyrite, violarite and natural copper. The metal oxide is magnetite. The associated elements have Co, Pt, Pd, Au, Ag, Os, Ir, Ru, Rhodium, Se, Te, Cr etc. The harmful elements have Pb, Zn, As, Bi. The chemical composition of ore is characterized of poor alkali, lower aluminium and calcium. Although a little differences of scale and neme-racalvalues, Heishan Ni-Cu deposit has the same condition with Jnchuan Ni-Cu deposit on geological setting of diagenesis and metallogensis, gravity and magnetic anomaly, occurrence of ore-bearing rock body, feature of ore body, petrochemistry and metallogenic elements, generally, these reflected similarity and consistency of two deposits on diagenesis and metallogenesis. Heishan district would be expected to be potential in depth. Regionally, around the area of gravity and magnetic anomaly on the deep-great fault at the edge of archicontinent or old block, the prospecting targets for magmatic Ni-Cu deposit should be focused on multi-phase intrusive outcrop or small scale concealed basic-ultrabasic complex body with anomaly zone of Fe, Cr, Ni, Co, V, Cu, Zn, Mn.

Wang H.,Chinese Academy of Geological Sciences | Yang Z.,Capital Normal University | Tong Y.,Chinese Academy of Geological Sciences | Gao L.,Chinese Academy of Geological Sciences | And 2 more authors.
International Geology Review | Year: 2016

The mechanism of deformation associated with the Cenozoic collision of India with Asia along the eastern boundary remains a poorly understood aspect of the tectonic evolution of the southwestern South China Block (SCB). Consequently, we carried out a palaeomagnetic investigation of Palaeogene red beds of the Dayao area of Yunnan Province in order to contribute to understanding the Palaeogene evolution of the SCB. A characteristic higher temperature magnetic component (HTC), with an unblocking temperature from 660°C to 680°C, was determined by principal component analysis (PCA), and positive fold tests indicated that the remanence was a primary magnetization. The mean direction of the HTC from the Dayao area is Ds = 27.8° Is = 33.1° κ = 64.8, α95 = 4.3° after tilt correction. Compared with other palaeomagnetic results from the SCB, our data suggest that the central part of the Chuan–Dian Fragment (CDF) experienced approximately 16.3 ± 4.7° clockwise rotation with respect to East Asia. Rotation of the CDF occurred along the left-lateral Xianshuihe–Xiaojiang Fault Systems (XSF-XJF), which exhibit an arc-shaped curve centred on the Eastern Himalayan Syntaxis. The XSF-XJF was approximated by a circle centred on a Euler pole at Lat. = 26.5° N, Lon. = 97.2° E (α95 = 0.2°), based on 11 reference points selected from the fault system. The clockwise rotation of the CDF resulted in left-lateral shearing along the XSF-XJF system, with a left-lateral displacement of ~200 km. The nature of diverse intense local deformation along the Xianshuihe-Xiaojiang left-lateral strike-slip fault systems is also discussed. © 2016 Taylor & Francis

Wang F.C.,Geological Survey of Gansu Province | Wang S.S.,Northwest University, China | Li T.D.,Exploration Team of Geophysics | Cai X.J.,Gansu Academy of Engineering Geology | Zhao L.,Lanzhou University
Acta Petrologica Sinica | Year: 2011

The granites were widely distributed in Qilianshan area, the mainly age is Early Paleozoic era, it can be divided into three types: ( 1) high Sr and low Y type granite ( adakite) ; ( 2 ) low Sr and high Y type granites; ( 3 ) A-type granite, according to the geochemistry. The granites of high Sr and Low Y type are divided into O-type (Na-riched) and C-type (K-riched) , the former is mainly in the eastern section of Qilianshan, the latter is mainly in the western part of Qilianshan. There are two main types of the copper mineralization in Qilianshan: Shijuli-type and Heishishan-type, the former is associated with the ophiolites, the latter is associated with the porphyry (adakite). Gold mineralization in the area are mainly distributed in the western part of Qilianshan, such as Hanshan and Yingzuishan, the mainly (such as Chelugou, Heicigou, Jiagongtai) are relates to adakite. Tungsten-tin-molybdenum mineralization in Qilianshan are mainly distributed in the western part of Qilianshan, the most are related to high Sr and low Y type granite (such as Yeniutan, Xiaoliugou, Jinfosi and Chaidanuoshan granites). Lead-zinc is associated with low Sr and high Y type granite (such as Nanba). The Xiaotieshan lead-zinc mine is related to A-type granites, it probably belong to latter of collision.

Liu S.,Geological Survey of Gansu Province
Northwestern Geology | Year: 2015

The Dewulu skarn-type copper deposit is located in western Qinling of south Shangdan Suture, Gansu Province. The intrusion of Dewulu ismainly granodiorite. The impulsive intrusion of the comagmatic magma formed granodiorite porphyry and micro-crystal quartz diorite, the later metalliferous magmatic hydrothermal filled and replaced the wall rock and formed skarnization marble and diopside-garnet skarn. The main industrial orebody occurs in the skarn. Mineralization concentrated in the complex zone that intercalated by intrusive dykes. The ore shoot occurs in the cove of the intrusion or the extending area of the apophyse. During the Indosinian movement in Middle-Late Triassic, deep earth crust melted and became magma, containing abundant mineral resources. Research results show that magma of deep crust melts carried abundant metallogenic materials to replace the wall rock and make the ore mineral precipitate in the condensation and diagenetic process, forming skarn-typeand hydrothermal-type mixed copper deposit. Areaswith early Yanshanian granodiorite, granite diorite porphyry (vein), quartz diorite porphyrite and diopside-garnet skarn, skarnization marble, area containing malachite, azurite, ferritization, and other oxidized minerals, accompanied by area with magnetic anomaly, secondary halo of copper and low resistivity, are favorable prospecting places. Thus, the Longdegang-Meiwuxinsi district is considered to be a favorable area for ore prospecting. More exploration and research work should be conducted there.

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