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Zhang Z.,Zhejiang University | Wu L.,Zhejiang University | Wang R.,Kunming Institute of Exploration | Zhang J.,Geological Exploration Technologies Institute of Anhui Province
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology)

The first kind of Fredholm integral equation in the downward continuation was solved by adopting conjugate gradient method with the assumption that the coefficient matrix is positive definite. The theoretical model test shows that downward continuation has a very fast convergence rate but suggests poor ability to compress the noise.compared with integral iteration method, conjugate gradient method indicates a faster convergence rate, as well as divergence rate, and is not so applicable. In order to acquire stable solutions the regularization of the operator of the ill-posed problem was carried out and the problem was transformed to solve the minimum value of the least squares estimations. After using the conjugate gradient method to solve the least squares problem, a method was implemented for downward continuation based on CGNR method that has a better ability to suppress noise. Model test demonstrates that this method has strong ability in restraining noise. This method convergence fast and has obvious computation advantage by a comparison with least square steepest descent method. Source

Shu X.-F.,China University of Geosciences | Shu X.-F.,Geological and Mineral Exploration Academy of Qinghai Province | Wang X.-P.,Qinghai Province Nuclear Industry Geology Bureau | Wang X.-P.,Xian Institute of Geology and Mineral Resources | And 2 more authors.
Northwestern Geology

Qimantag metallogenic belt is very important copper-polymetallic metallogenic beltin Qinghai. Copper-lead-zinc deposits in the Hutouya area composed of Hutouya and Yingqinggou deposit. The deposit prospecting has made great progress in recent years, but the genetic types of deposits remains controversial. Through detailed field observations, we collected evidence from different angles, and then determined two genetic types for the deposits: one belongs to hydrothermal deposit related to Triassic bodies, Tanjianshan group in Ordovician to Silurian, and Di'ao Formation in Late Carboniferous; the other related to Mesoproterozoic Langyashan Formation belongs to SEDEX-hydrothermal superimposition-transformation deposit. At the same time, ore-controlling factors were analyzed and prospecting criteria was established to guide the exploration. Source

Chen B.-Y.,Yunnan Nonferrous Metals Geological Bureau | Liu H.-T.,Kunming Institute of Exploration | Yang P.,Institute of Geology | Sun Y.,Yunnan Nonferrous Metals Geological Bureau
Acta Geoscientica Sinica

The global lateritic nickel ore deposits have distinct temporal and spatial distribution regularity, and the lateritic nickel ore bodies are characterized by apparent vertical zoning. The intensity of lateritic nickel mineralization is obviously influenced and controlled by the components of ore-forming parent rock (such as nickel content and lithogeochemical and mineral composition), climate, topography, hydrogeology, structural geology, duration of ore-forming process, and maturity of the weathering crust. Types of lateritic nickel ore deposits are mainly controlled by climate, tectonic setting and the state of structural uplift and also influenced by topography, drainage condition, lithology of ore-forming parent rock and its serpentinization. Source

Yang J.,Central South University | Yang Y.,Central South University | Yang Y.,Kunming Institute of Exploration | Yan L.,Changsha University of Science and Technology | And 4 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

Lijiachong large-span tunnel is excavated below the existing high-voltage transmission tower, and the risk of tunnel construction is very high. Several possible schemes for tunnel construction and foundation reinforcement of high-voltage transmission tower were presented based on risk analysis; and comparison among tunnel excavation using two-side wall drift heading method after mountain grunting consolidation, tunnel excavation using three bench method with the core of surrounding rock remained after tower foundation were reinforced with H-shaped framed girders, and tunnel excavation using three bench method with the core of surrounding rock remained after tower foundation were underpinned are introduced through a 3D numerical analysis of the interaction between tunnel construction and high-voltage transmission tower. The scheme of using H-shaped framed girders to connect the foundations as a whole is adopted. It is shown that after the pile foundations were connected with H-shaped framed girders, the foundations worked as a whole, tunneling using three bench method with the core of surrounding rock remained became safety. Cumulative settlement and uneven settlement were well controlled, and the forces and deformations of the tower were in the allowable ranges. By reinforcing the tower foundations using the H-shaped framed girders, Lijiachong tunnel safely passed beneath the transmission tower; and good economical and technical results are obtained. The results can provide a reference for similar projects. Source

Li J.-S.,Kunming Institute of Exploration | Li G.-D.,Yunnan Nonferrous Metals Geological Bureau | Zhang Y.-X.,Kunming Institute of Exploration | Zhang X.-F.,Kunming Institute of Exploration | Wang C.,Kunming Institute of Exploration
Acta Geoscientica Sinica

Based on an analysis of ore-forming geological background and geological characteristics of the Shanmuqing Fe-Cu deposit in Dongchuan of Yunnan Province and using the information in such aspects as the metallogenic conditions of Fe-Cu deposit of Dongchuan model, the Xikuangshan model of the neighboring area, the dome structure, the gravity-magnetic anomaly, the geochemical anomaly and the mineralization, in combination with the newest results in geological exploration of Yunnan Province, the authors analyzed and studied the ore-prospecting potential of the exploration area. Considering that its metallogenic characteristics and geophysical-geochemical anomaly are similar to those of the Luoyin Fe-Cu ore belt, the authors delineated two gravity-magnetic anomaly belts of Linggongli-Xiaopo and Erbaier-Xinzhai and their nearly areas as prospecting targets. It is inferred that there exists great prospecting potential in search for middle-large ore bodies at the depth. Source

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