Chen Y.-T.,Northwest University, China |
Zhang G.-W.,Northwest University, China |
Lu R.-K.,Northwest University, China |
Lu R.-K.,Anhui Institute of Geological Survey |
Zhang Y.-Q.,Lizi Goldmine Company Ltd of China National Gold Group Corporation
Geological Bulletin of China | Year: 2010
The samples of mylonite were collected from the Guozhacuo fault, situated in the southwestern end of Altyn Tagh fault zone, which extends from Guozhacuo to Longmuco and then to Kongkashankou. The plateau ages of the syntectonic biotite contained in the samples by means of 40Ar/40Ar isotopic dating are listed as follows: 105.9 ± 0.5 Ma, 121.5 ± 0.6 Ma, 150.4 ± 0.9 Ma, which indicated that the ductile deformation of early stage occurred in the Late Jurassic and Early Cretaceous in Guozhacuo fault, and they were consistent with main stages of activities of Altyn Tagh fault zone. Consequendy new evidence has been provided for the extension of Altyn Tagh fault zone towards west. That is to say, Guozhacuo fault has the consistent characteristics of deformation geochronology and tectonic attribute with Altyn Tagh fault zone, and the former is the western extension of the latter, both of them are of the same tectonic belt and are also the results of impulsive tectonic activity caused by northward movement of Lhasa block.
Yu X.,China University of Geosciences |
Wang D.,Bureau of Mineral Resources |
Jiang D.,University of London |
Jiang L.,Anhui Institute of Geological Survey |
And 2 more authors.
Acta Geologica Sinica | Year: 2011
The major tectonic zone that passes through the border regions of the Anhui, Zhejiang, and Jiangxi Provinces in southeast China has been commonly referred to as the Wan-Zhe-Gan fault zone. Geologically, this zone consists ofseveral regional fault belts of various ages and orientations. We have categorized the faults into four age groups based on field investigations. The Neoproterozoic faults are northeast striking. They start from the northeast Jiangxi Province and extend northeastward to Fuchuan in Anhui Province, the same location of the northeast Jiangxi-Fuchuan ophiolite belt. The faults probably acted during the Neoproterozoic as a boundary fauIt zone of a plate or a block suture with mélange along the faults. The nearly east-west- or east-northeast-striking faults are of Silurian ages (40Ar/39Ar age 429 Ma). This group includes the Qimen-Shexian fault and the Jiangwang-Jiekou ductile shear belt. They represent a major tectonic boundary in the basement because the two sides of the fault have clear dissimilarities. The third group of faults is north-northeast striking, having formed since the early-middle Triassic with 40Ar/39Ar ages of 230-254 Ma. They form a fault beIt starting from Yiyang in northern Jiangxi and connect with the Wucheng as well as the Ningguo-Jixi faults. This fault belt is a key fault-magmatic belt controing the formation of Jurassic-Cretaceous red basins, ore distribution, magmatic activity, and mineralization. When it reactivated during the late Cretaceous, the belt behaved as a series of reverse faults from southeast to northwest and composed the fourth fault group. Therefore, classifying the Wan-Zhe-Gan fault zone into four fault groups wil1 help in the analysis of the tectonic evolution of the eastern segment of the Jiangnan orogen since the Neoproterozoic era.
Guan H.,Nanjing University |
Guan H.,Anhui Institute of Geological Survey |
Zhu C.,Nanjing University |
Zhu T.,University of Minnesota |
And 2 more authors.
Journal of Asian Earth Sciences | Year: 2016
Rare studies on the aeolian deposit located in north bank of the Yantgze River are documented. Recently, it is found in the field investigations and in bore sections that the loess in the Chaohu lake basin has the largest thickness of over 40. m. In this study, the probability cumulative curves, frequency distribution, the grain size distributions and the discriminant function of the grain size suggest that the loess in the Chaohu lake basin is of eolian origin. The magnetic susceptibility curves of the loess in the basin coincide perfectly with those of the loess in the northern China and the marine isotope stages (MIS), and show that paleoclimatic cycles and sub-cycles were documented since L3 during middle-late Pleistocene in the basin. The MS curve of Paleosol S1, Paleosol S2 and loess L3 in the basin coincide perfectly with MIS5, MIS-7 and MIS-8, respectively. The good correspondence indicates that the loess in the basin has given a sensitive response to the globe paleoclimatic change since L3. On the other hand, the climate changes in some stages recorded by the loess has regional characteristics obviously, which might be the result of the dual effect of globe climate changes and East-Asia monsoon climate changes. The result of geochemical characteristics suggests that the loess in the basin has undergone moderate to strong chemical weathering. Most elements are mobilized during chemical weathering; Na and Ca of the loess are markedly lost and the removal of K is also evident, and chemical weathering doesn't evidently turn into the Si removal stage. The chemical weathering of the loess is more intensive than that of the loess deposits in northwestern China and the upper reaches of the Yantgze River. The intensive chemical weathering has been documented by the loess might be related to strong monsoon climate in Chaohu lake basin. The provenance of the loess also differs from that in northern China, and is discussed firstly with the lithofacies palaeogeography. The well-developed alluvial-lacustrine deposits in the Huaihe floodplain seem to be the major source materials of the loess. © 2015 Elsevier Ltd.
Qian J.,Hefei University of Technology |
Chen Z.,Hefei University of Technology |
Zhan H.,Texas A&M University |
Zhan H.,Wuhan University |
Guan H.,Anhui Institute of Geological Survey
Hydrological Processes | Year: 2011
Local cubic law (LCL) is one of the most commonly applied physical laws for flow in single fractures (SF) and fractured media. The foundation of LCL is Darcian flow. This experimental study examines if LCL is valid for flow in a single rough fracture and how the fracture roughness and Reynolds number (Re) affect flow. Similar to the Moody diagram for flow in pipes, a diagram for flow in a single rough fracture has been generated to relate the friction coefficient with Re and the roughness. Under the experimental condition of this study, flow appears to be substantially different from Darcian flow. The flow law of q ∝ enJm appears to be valid for describing the flow scheme where q, e, and J are the unit width flux, the average aperture, and the hydraulic gradient. The value of the power index m is found to be around 0·83 ~ 0·98, less than what has been used in Darcian flow (m = 1). The power index n is around 11·2 and 13·0, much greater than the n value used in the LCL (n = 3), and it increases with the average velocity. The Moody type of diagram shows that the friction factor for flow in SFs is influenced by Re and the roughness. It decreases with Re when Re is small, and becomes less sensitive to Re when Re is large enough. It also increases with the roughness. Copyright © 2010 John Wiley & Sons, Ltd.
Wan Q.,Anhui Institute of Geological Survey |
Du J.,Anhui Institute of Geological Survey
Northwestern Geology | Year: 2015
According to metallogenic geological conditions and characteristics of Tongling area, and results of previous studies, deep mineralization and its process were discussed in this paper. Structural analysis shows that the Tongling area covers more than one deformation system with multiple stages. The deformation is dominant by fold and fault, and the deformation properties of strata below Silurian may have already changed; magmatic process showsthat ore-bearing rock are mainly syntectic granitoid; magma tite has obvious mineralization-exclusive characteristics. Copper-gold related rocks are mainly high-K calc-alkaline rocks, while iron-bearing and sulfur-bearing volcanic intrusionsare basically kohalaite rock series. Spatial distribution of magmatic rocks is mainly controlled by tectonic structure; magmatic hydrothermal migration in deep percolation is of middle scale, intruding upward in shallow as dykes. There is certain coupling relationship between ore-forming rock and surrounding rock. The ore mineralization takes place in Yanshanian. The summary of deposit distribution, types and mineralization law, combined with the mineralization prediction theory, the mineralization area, type and location were predicted. The study can provide reference forthe deep exploration in the Tongling area.
Chen X.-R.,Anhui Institute of Geological Survey |
Chen F.-R.,Anhui Institute of Geological Survey |
Jia S.-J.,Anhui Institute of Geological Survey |
Chen Y.-N.,Anhui Institute of Geological Survey
Geology in China | Year: 2012
Geoc hemical parameters of top and deep soils as well as geochemical baseline and background were calculated based on multi-purpose regional geochemical survey covering Yangtze River-Huaihe River basin of Anhui Province. The concentrations of most elements in top soils are mainly controlled by their concentrations in deep soils. The concentrations of some elements in different soil layen are apparendy different. Soil formation processes and anthropogenic activities have had remarkable impact on the distribution of elemental concentrations in soils. It is demonstrated that soil parent material usually has significant influence on geochemical baseline. Geochemical baselines of soils derived from the same parent materials have the tendency to vary in different geographical units. Therefore calculation of soil geochemical baseline should consider spatial variation. These results can be widely used in eco-geochemistry and related multi-discipline research.
Li B.,Anhui Institute of Geological Survey |
Zhang Z.,Anhui Institute of Geological Survey |
Wu M.,Anhui Institute of Geological Survey |
Zhou T.,Hefei University of Technology |
And 3 more authors.
Geological Bulletin of China | Year: 2015
The Dawujian deposit is a typical stratabound skarn W-Mo deposit located on the northeastern margin of the Qin-Hang metallogenic belt. The determination of the ages of the mineralization and the magmatic rocks of the Dawujian deposit is very important for the study of deposit genesis and regional metallogenic regularity. On the basis of geological and petrographic studies, the authors collected the primary types of magmatic rocks and molybdenite of the main mineralization stage and obtained the ages of the magmatic rocks (148.3±2.2 Ma, 148.5±2.1 Ma) by LA-ICP-MS zircon U-Pb dating and the age of mineralization (144.4±1.5 Ma) by Re-Os dating of the Dawujian deposit. The authors also reveal that the Dawujian deposit was formed by magmatite intrusion of the first stage of Yanshanian period (150~136 Ma). This stage seems to be an important metallogenic period in the south of Anhui Province, which was formed in a regional compressional environment from the transform of the Paleo-Tethys tectonic domain to the Pacific tectonic domain. ©, 2015, Science Press. All right reserved.
Guan H.-C.,Nanjing University |
Guan H.-C.,Anhui Institute of Geological Survey |
Li Y.-H.,Anhui Institute of Geological Survey |
Liu D.-B.,Anhui Institute of Geological Survey |
And 2 more authors.
Geology in China | Year: 2015
The OSL dating results show that the deposition of the Xiashu Loess (Xiashu Formation) in the Hefei Basin began in the late period of the Middle Pleistocene. In this study, the major geochemical elements and grain sizes of the Xiashu Loess in Hefei were compared with those of Northwest (NW) loess, Xiashu Loess of Zhenjiang, Wushan Loess and Xuancheng Loess. The provenance of the Xiashu Loess in Hefei was discussed. Studies of geochemical characteristics, grain size content and deposition rate show that the provenance of the Hefei Xiashu Loess differs from that of the nearby Zhenjiang loess and the Northwest China Loess which were derived from the northern deserts. The lithofacies palaeogeography and the paleoclimate indicate that the abundant fine-grained sediments of the alluvial-lacustrine deposits in the Huaihe floodplain seem to be the major source materials of the Hefei Xiashu Loess.
Dong Z.-Y.,Chinese Academy of Sciences |
Dong Z.-Y.,University of Chinese Academy of Sciences |
Liu D.-W.,Chinese Academy of Sciences |
Wang Z.-M.,Chinese Academy of Sciences |
And 6 more authors.
Chinese Journal of Applied Ecology | Year: 2013
By using GIS/RS technology, and from the aspects of landscape structure, river- and road densities, wetness index, geomorphology, and cultivated land productivity, a spatial analysis was made on the potentiality of wetland restoration in Northeast China, with the regions of priority and secondary priority restoration wetlands determined. Then, by using the coordinated development index of crop production and wetland as well as the landscape indices, the wetland restoration effect was verified. In Northeast China, the wetland area of priority restoration was 1.78×106 hm2, among which, farmland and grassland were the main types for restoration, accounting for 96.7% of the total, and mainly located in the Sanjiang Plain in the northeastern part and the Songnen Plain in the central part of Northeast China. The wetland area of secondary priority restoration was 1.03×106 hm2. After the restoration of the wetlands, the wetland area in Northeast China would be increased by 37.4%, compared with the present wetland area, and the value of the coordinated development index of crop production and wetland would increase from 0.539 before restoration to 0.733 after restoration. The landscape pattern would be more benefit to the performance of the ecological functions of the wetlands. This study revealed that the restoration scheme of the wetlands in Northeast China based on spatial analysis was practicable, which could provide data support for the implement of wetland restoration and the improvement of ecological environment in Northeast China.
Huang J.,Anhui Institute of Geological Survey |
Lu R.H.,Anhui Institute of Geological Survey |
Lu R.H.,Northwest University, China |
Chu Z.,No. 6 Geological Party |
Zhang Y.-Q.,Lizi Gold Mine Co.
Geology in China | Year: 2011
The parameters of magnetic fabrics of deformed rocks such as K max, Kint, Kmin, P, T, F, L and E can be used to quantitatively display the behaviors of tectonic deformation. Characteristics of magnetic fabrics of the ductile shear zone in Sandaogou area of Inner Mongolia were analyzed in this study. The results show that most E values are larger than or close to 1; T values larger than 0 are more than those smaller than 0; P values are larger than 1, and the data in graphic variant Flinn of the L.-F parameters of magnetic fabrics are concentrated in the shear zone and the compression zone. It is indicated that the magnetic susceptibility ellipsoid mainly finds expression in flatted ball ellipsoid whose foliation is more developed than lineation. The rocks in Sandaogou ductile shear zone experienced a strong tectonic activity of extrusion shear mechanical mechanism.The stress, strain and deformation characteristics are consistent with field features and microstructure.