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341.
342.
保山镇康地块矽卡岩型铅锌矿床成因初探 总被引:4,自引:0,他引:4
保山镇康地块是"三江"南段重要的铅锌多金属成矿区之一,地质构造复杂,铅锌成矿地质条件优越,其中核桃坪与芦子园是近年发现的两个大型铅锌矿床,矿床受近NE向断裂、背斜轴部和地层控制明显,上寒武统核桃坪组与沙河床组大理岩化灰岩为主要赋矿地层,近矿围岩矽卡岩化强烈,流体包裹体,Pb、S、H、O同位素和微量元素等地球化学对比研究表明:核桃坪和芦子园铅锌矿床均经历了中温、高温两个矿化阶段;核桃坪铅锌矿床矿石铅同位素较芦子园铅锌矿床有较高的比值和较大的变化范围,均以高μ值为特征,属于放射性成因铅,暗示其成矿物质以壳源铅为主;硫化物硫同位素均多为较低正值并呈塔式分布,具有岩浆硫特征,两者均无生物硫酸盐热化学还原作用的参与,其中硫同位素分馏已达平衡;与硫化物共生的石英δDH2O(-109‰~-91‰)和δ18OH2O(-4.3‰~2.3‰)同位素研究表明核桃坪矿床成矿流体主要来自深部岩浆水,并遭受后期大气降水或地层水的混合;核桃坪矿床与芦子园矿床的微量元素具有岩浆热液型矿床特征,不同于VMS型、MVT型铅锌矿床。因此,笔者认为两个矿床应属于与深部隐伏岩体有关的中-高温矽卡岩型铅锌矿床,矿区深部隐伏岩体的侵入产生岩浆热液并携带Pb、Zn等成矿物质与地层水或大气降水混合,在背斜轴部与NE向断裂的交汇处形成该类型矿床。 相似文献
343.
Yan-Jun Li Jun-Hao Wei Hua-Yong Chen Jun Tan Le-Bing Fu Gang Wu 《Mineralium Deposita》2012,47(7):763-780
The Maoduan Pb–Zn–Mo deposit is in hydrothermal veins with a pyrrhotite stage followed by a molybdenite and base metal stage. The Re–Os model ages of five molybdenite samples range from 138.6 ± 2.0 to 140.0 ± 1.9 Ma. Their isochron age is 137.7 ± 2.7 Ma. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating of the nearby exposed Linggen granite porphyry gave a 206Pb/238U age of 152.2 ± 2.2 Ma and the hidden Maoduan monzogranite yielded a mean of 140.0 ± 1.6 Ma. These results suggest that the intrusion of the Maoduan monzogranite and Pb–Zn–Mo mineralization are contemporaneous. δ 34S values of sulfide minerals range from 3.4‰ to 4.8‰, similar to magmatic sulfur. Four sulfide samples have 206Pb/204Pb = 18.252–18.432, 207Pb/204Pb = 15.609–15.779, and 208Pb/204Pb = 38.640–39.431, similar to the age-corrected data of the Maoduan monzogranite. These isotope data support a genetic relationship between the Pb–Zn–Mo mineralization and the Maoduan monzogranite and probably indicate a common deep source. The Maoduan monzogranite has geochemical features similar to highly fractionated I-type granites, such as high SiO2 (73.7–75.2 wt.%) and alkalis (K2O + Na2O = 7.8–8.9 wt.%) and low FeOt (0.8–1.3 wt.%), MgO (~0.3 wt.%), P2O5 (~0.03 wt.%), and TiO2 (~0.2 wt.%). The granitic rocks are enriched in Rb, Th, and U but depleted in Ba, Sr, Nb, Ta, P, and Ti. REE patterns are characterized by marked negative Eu anomalies (Eu/Eu* = 0.2–0.4). The Maoduan monzogranite, having (87Sr/86Sr) t = 0.7169 to 0.7170 and εNd(t) = −13.8 to −13.7, was probably derived from mixing of partial melts from enriched mantle and the Paleoproterozoic Badu group in an extensional tectonic setting. 相似文献
344.
J. S. Chen X. X. Sun W. Z. Gu H. B. Tan W. B. Rao H. Z. Dong X. Y. Liu Z. G. Su 《Geochemistry International》2012,50(5):455-465
Despite its extreme aridity, the Badain Jaran Desert is rich in groundwater. In the southeastern part of the desert, it is
characterized by coexistence of high megadunes and a great number of lakes. Deuterium and oxygen 18 isotope compositions as
well as hydrochemistry of groundwater, lake water, soil water and river water were investigated in detail to gain an insight
into their relationships and the origin of the ground-water. The results show that the groundwater and the lake water are
genetically related, but unrelated to local precipitation and the leakage of Heine River at northern slope of Qilian mountain.
δD and δ18O values of deep soil water (lower than 40 cm) and groundwater plot on the same evaporation line E11, which shows that they
have the same recharge source. The point of intersection between E11 and LMWL suggests that the groundwater originates from
the water resource which has a weighted mean value that is lighter by some 6‰ δ18O than the local precipitation in Badain Jaran Desert. 3H data of water samples shows that the groundwater in Badain Jaran Desert originates from the water recharged after the nuclear
test. The deep fault zone underground maybe the water circulation channel based on Helium analysis of groundwater. The result
has guiding significance to rational exploitation and utilization of the local groundwater. 相似文献
345.
The 2010 Yushu earthquake triggered landslide hazard mapping using GIS and weight of evidence modeling 总被引:11,自引:3,他引:8
Chong Xu Xiwei Xu Yuan Hsi Lee Xibin Tan Guihua Yu Fuchu Dai 《Environmental Earth Sciences》2012,66(6):1603-1616
The Yushu County, Qinghai Province, China, April 14, 2010, earthquake triggered thousands of landslides in a zone between
96°20′32.9″E and 97°10′8.9″E, and 32°52′6.7″N and 33°19′47.9″N. This study examines the use of geographic information system
(GIS) technology and Bayesian statistics in creating a suitable landslide hazard-zone map of good predictive power. A total
of 2,036 landslides were interpreted from high-resolution aerial photographs and multi-source satellite images pre- and post-earthquake,
and verified by selected field checking before a final landslide-inventory map of the study area could be established using
GIS software. The 2,036 landslides were randomly partitioned into two subsets: a training dataset, which contains 80 % (1,628
landslides), for training the model; and a testing dataset 20 % (408 landslides). Twelve earthquake triggered landslide associated
controlling parameters, such as elevation, slope gradient, slope aspect, slope curvature, topographic position, distance from
main surface ruptures, peak ground acceleration, distance from roads, normalized difference vegetation index, distance from
drainages, lithology, and distance from all faults were obtained from variety of data sources. Landslide hazard indices were
calculated using the weight of evidence model. The landslide hazard map was compared with training data and testing data to
obtain the success rate and predictive rate of the model, respectively. The validation results showed satisfactory agreement
between the hazard map and the existing landslide distribution data. The success rate is 80.607 %, and the predictive rate
is 78.855 %. The resulting landslide hazard map showed five classes of landslide hazard, i.e., very high, high, moderate,
low and very low. The landslide hazard evaluation map should be useful for environmental recovery planning and reconstruction
work. 相似文献
346.
Examination of loose saturated sands impacted by a heavy tamper 总被引:1,自引:1,他引:0
This article examines the densification effects on the loose saturated sands impacted by a heavy steel tamper dropped from a great height (i.e., deep dynamic compaction, DDC). This examination was achieved by carrying out a series of piezocone penetration test (CPTu) soundings before and after the DDC impact. The depths at which densification took place ranged from 6.5 to 9.5 m below the ground surface (BGS) after one pass of DDC, and from 7.5 to 11.0 m BGS after two passes. The propagation of the surface waves generated in DDC disturbed the top 0.3–1.3 m soils. Directly below this disturbed layer, it was the most densified soil layer at the depths of 1.7–4.5 m BGS. The existence of the residual soft peat pockets reduced the densification effects substantially. Both the strength and the stiffness of the loose saturated sands were significantly improved after the DDC treatment. After two passes of impact, the liquefiable soils were densified to the level of unliquefiable along with dramatic reduction in liquefaction probabilities when subjected to earthquake motions. 相似文献
347.
The assessment of water stress with the Water Poverty Index in the Shiyang River Basin in China 总被引:1,自引:0,他引:1
Ruijun Zhang Zhenghu Duan Mingliang Tan Xiaohong Chen 《Environmental Earth Sciences》2012,67(7):2155-2160
The paper is concerned with the application of the Water Poverty Index (WPI) as a holistic tool to assess the Shiyang River Basin’s water stress at the regional level. The basin is one of the inland river basins in China, with the degree of exploitation and utilization of water resources very high and water scarcity most severe. Appropriate indicators are needed to measure water stress for policy making and decision-making. The WPI links physical estimates of water availability with socio-economic factors associated with water scarcity. The study presents details of the methodology used, and the results show that the water stress in Minqin is the most severe in the basin, with a WPI value of 26.3, and that the water situation is the best in Jingchang with a WPI score of 66.9. In addition, measures in the basin are obtained of resources, access, capacity, use and environment. 相似文献
348.
基于有理多项式系数模型的物方面元最小二乘匹配 总被引:2,自引:1,他引:1
针对物方面元最小二乘匹配仅适用于单中心投影框幅式成像的匹配制作区域DSM问题,提出基于有理多项式系数(RPC)模型的物方面元最小二乘匹配算法,结合匹配窗口区域内多中心平行投影方式,构建RPC模型下的投影方程,将物方面元最小二乘匹配算法从适用于单中心投影框幅式成像扩展到适用于多中心投影推扫式成像的立体匹配,并用SPOT5-HRG、GeoEye、IKONOS立体影像进行试验验证。试验表明,RPC模型能用于物方面元最小二乘匹配且不损失匹配精度,增加了物方面元最小二乘匹配的应用范围和价值。 相似文献
349.
Solar photocatalytic decolorization and detoxification of batik dye wastewater using titanium dioxide (TiO2) immobilized on poly‐3‐hydroxybutyrate (P(3HB)) film was studied. The effects of initial dye concentration, catalyst concentration, P(3HB) film thickness, and fabrication methods of the nanocomposite films were evaluated against methylene blue, a standard organic dye. It was observed that 0.4 g of P(3HB)‐40 wt% TiO2 removed 96% of the color under solar irradiation. P(3HB) and TiO2, mixed concurrently in chloroform followed by stirring for 24 h showed a more even distribution of the photocatalyst on the polymer surface and yielded almost 100% color removal. The photocatalytic films were able to completely decolorize real industrial batik dye wastewater in 3 h and induced a chemical oxygen demand (COD) reduction of 80%. Reusability of the 0.4 g P(3HB)‐40 wt% TiO2 film in decolorizing the batik dye wastewater was also possible as it gave a high consistent value of decolorization percentage (>80%) even after the sixth repeated usage. Recovery step of the photocatalysts was also not required in this simple treatment system. The decolorized batik dye wastewater had less/no toxic effects on mosquito larvae, Aedes aegypti, and microalgae, Scenedesmus quadricauda indicating simultaneous detoxification process along with the decolorization process. 相似文献
350.
Trace element and REE geochemistry of fine- and coarse-grained sands in the Ordos deserts and links with sediments in surrounding areas 总被引:1,自引:0,他引:1
Wenbo Rao Hongbing Tan Sanyuan Jiang Jiansheng Chen 《Chemie der Erde / Geochemistry》2011,(2):155-170
In addition to mineral analyses, REE and trace element geochemical characteristics of fine- and coarse-grained sands in the Ordos deserts and other sediments in surrounding areas are investigated.Commonly the samples consist of quartz, feldspar and muscovite and less clinochlore, dolomite and ankerite. In few samples muscovite is absent.REE and trace compositions are spatially uniform for the same grain-size sands, suggesting that they could have the same sources or/and were well homogenized. However, fine- and coarse-grained sands in the Ordos deserts show different REE and trace element compositions. Fine-grained sands show higher contents of REE and trace elements than those of coarse-grained sands. They differ in Eu anomalies and (La/Yb)N ratios although both fractions are characterized by the steep LREE and smooth HREE patterns. The fine- and coarse-grained sands are also distinct in some characteristic element ratios (e.g., Th/Co, La/Sc, Th/Sc and Y/Ni).REE and trace element patterns of the two different grain-size fractions are closely associated with geological properties of individual sources rather than the mineralogical differentiation induced by wind sorting. The coarse-grained sands mainly resulted from sandstone weathering in the Ordos deserts and movements of coarse particles by wind. REE and trace element patterns of fine-grained sands in the Ordos deserts differ from those of sandstones in the Ordos deserts, the alluvial sands in the surrounding mountains and the coarse fluvial sands in the Yellow River. They resemble the fine fluvial sands in the Yellow River. In addition, arid areas of Northwest China such as the Tarim Basin and the Alxa Plateau should not be ruled out as the source of the fine-grained sands in the Ordos deserts because these arid areas reserve plenty of fine-grained sediments and also located in the upwind directions of the Ordos deserts. 相似文献