bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Sediments in the Yutian‐Hotan Oasis, South Xinjiang, China
Authors: Baosheng LI , ZHANG David Dian , Xingjia ZHOU , Feng ZHU , Baoyin YUAN , Guijin MU , Sen LI , Mancun YAN , Heling JIN , Quanzhou GAO , Wu SUN
Published: September 2010

Abstract  Based on investigation of sediments in the Yutian‐Hotan Oasis at the southern margin of the Tarim basin, 14C ages and grain‐size and chemical element analyses, the following views are put forward in this paper.

Sediments in the Yutian‐Hotan Oasis are composed chiefly of “oasis soil”, similar to the recent oasis soil, i.e. brown desert soil, which was formed due to pedogenesis after aeolian sand (sandy loam) and dust (loess) of 3.32–6.64ϕwere deposited.

The ancient Yutian‐Hotan Oasis represented by oasis soil was formed at 13000 a B.P. During the cold period of the past 13000 years, this region is characterized mainly by accumulation of sand and dust storms, and sandy oasis soil was developed in this region due to pedogenesis in an oasis environment; during the warm period, dust falls predominated along with certain current concomitants (lacustrine facies), and silty oasis soil was formed by pedogenesis. Owing to fluctuations of cold and warm climates since 13000 a B.P., sandy oasis soil was deposited alternately with silty oasis soil and lacustrine soils. Nevertheless, the Yutian‐Hotan Oasis has been preserved and developing continuously towards the contemporary time.

At the latest, the oasis became an important site of human inhabitancy at 10000 a B.P., and since then it has been an important base for the propagation and activity of local people in the Tarim Basin.
Geochemistry of Two Types of Basalts in the Emeishan Basaltic Province: Evidence for Mantle Plume‐Lithosphere Interaction
Authors: Zhaochong ZHANG , Fusheng WANG
Published: September 2010

Abstract  Based on the temporal‐spatial distribution and geochemical characteristics, the Emeishan basalts can be divided into two types: high‐P2O‐TiO2 basalt (HPT) and low‐P2O5‐TiO2 basalt (LPT), which differ distinctly in geochemistry: the LPTs are characterized by relatively high abundances of MgO, total FeO and P2O5 and compatible elements (Cr, Ni, Sc), and relatively low contents of moderately compatible elements (V, Y, Yb, Co), LREE and other incompatible elements compared with the HPT. On the diagrams of trace element ratios, they are plotted on an approximately linear mixing line between depleted and enriched mantle sources, suggesting that these two types of basalts resulted from interactions of varying degrees between mantle plume and lithospheric mantle containing such volatile‐rich minerals as amphibole and apatite. The source region of the LPT involves a smaller proportion of lithospheric components, while that of the HTP has a larger proportion of lithospheric components. Trachyte is generated by partial melting of the basic igneous rocks at the base of the lower continental crust. Both the two types of magmas underwent certain crystal fractionation and contamination of the lower crust at high‐level magma chambers and en route to the surface.
Mantle Redox State Evolution in Eastern China and Its Implications
Authors: Jianping LI , Jian WANG
Published: September 2010

Abstract  Using the secondary spinel standard, the authors have precisely measured the Fe3+/Σ Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, and estimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine‐orthopyroxene‐spinel oxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle in eastern China are higher in the south than in the north. Among them, the oxygen fugacity of the North China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, while that of Northeast and South China are the same as that of the global continental mantle. The variations of mantle redox state in eastern China are mainly controlled by the C‐O‐H fluids derived from the asthenospheric mantle. According to the mantle oxidation state, it can be concluded that the C‐O‐H fluids in the lithospheric mantle of eastern China consist mainly of CO2 and minor H2O, but CH4‐rich fluids should come from the asthenosphere where the oxidation state is lower.
A Successive Shift Box‐Counting Method for Calculating Fractal Dimensions and Its Application in Identification of Faults
Authors: Xiaohua SHEN , Lejun ZHOU , Hongsheng LI , Zhongyue SHEN , Shufeng YANG
Published: September 2010

Abstract  Fractal dimensions of a terrain quantitatively describe the self‐organized structure of the terrain geometry. However, the local topographic variation cannot be illustrated by the conventional box‐counting method. This paper proposes a successive shift box‐counting method, in which the studied object is divided into small sub‐objects that are composed of a series of grids according to its characteristic scaling. The terrain fractal dimensions in the grids are calculated with the successive shift box‐counting method and the scattered points with values of fractal dimensions are obtained. The present research shows that the planar variation of fractal dimensions is well consistent with fault traces and geological boundaries.
A Preliminary Study of the Gas Hydrate Stability Zone in the South China Sea
Authors: Chunshuang JIN , Jiyang WANG
Published: September 2010

Abstract  Based on the analysis of sea‐bottom temperature and geothermal gradient, and by means of the phase boundary curve of gas hydrate and the sea‐bottom temperature versus water depth curve in the South China Sea, this paper studies the temperature and pressure conditions for gas hydrate to keep stable. In a marine environment, methane hydrate keeps stable at water depths greater than 550 m in the South China Sea. Further, the thickness of the gas hydrate stability zone in the South China Sea was calculated by using the phase boundary curve and temperature‐depth equations. The result shows that gas hydrate have a better perspective in the southeast of the Dongsha Islands, the northeast of the Xisha Islands and the north of the Nansha Islands for thicker stability zones.
A New Method for Clay Mineral Analysis and Its Application in Geology
Authors: Hejing WANG , Anhuai LU , Tao CHEN
Published: September 2010

Abstract  X‐ray diffraction (XRD) peaks in a low‐angle diffraction section of clay minerals, especially those of authigenic origin, have broadening and tailing features in shape. Using the five basic parameters, peak position, peak height, width, shape coefficient and asymmetry, to describe an XRD peak is more accurate, comprehensive and integrated than using only 3 of them, position, height and width. Following the concept of the five basic parameters of an XRD peak, the program Decoform proposed in this study provides more information in mineralogical analyses by fitting actual XRD profiles. In combination with the HW‐IR plot, Decoform can be systematically and accurately used in the comprehensive analyses of crystallinity, domain size, lattice strain and quantitative phase. It is also of value for the geological investigations of diagenesis, metamorphism, basin maturity, structural stress field and so on.
Influences of Low‐Temperature Hydrothermal Fluids on the Re‐distributions and Occurrences of Associated Elements in Coal — A Case Study from the Late Permian Coals in the Zhijin Coalfield, Guizhou Province, Southern China
Authors: Shifeng DAI , Deyi REN , Yuegang TANG , Longyi SHAO , Liming HAO
Published: September 2010

Abstract  The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma‐atomic emission spectroscopy, and a scanning electron microscope equipped with an energy‐dispersive X‐ray analyzer. And, a microscope photometer system (Leitz MPV‐III) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low‐temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally‐altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low‐temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM‐A, HAOM‐B, HAOM‐C, and HAOM‐D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low‐temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low‐temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low‐temperature hydrothermal fluids play a crucial role in the re‐distributions and occurrences of associated elements in coal.
Fractal Principle of Mineral Deposit Size Forecasting and Its Implication for Gold Resource Potential Evaluation in China
Authors: Changjiang LI , Tuhua MA , Xingsheng ZHU , Guowu WANG
Published: September 2010

Mineralization distributions are very heterogeneous in nature. As large or superlarge mineral deposits are quite rare whether in time or in space, it is difficult to detect all the largest mineral deposits in a region in a limited period of time owing to the restriction of technology and exploration degrees—this is called “not all discovered”. However, all discovered large, especially superlarge, mineral deposits generally have a complete census in the geological literatures. On the other hand, not all discovered small mineral deposits are recorded in the geological literatures because for economic reasons people have not much interest in them—this is called “not all recorded”. This practice often results in the observation truncations, that is, the data points near the two ends in an observable population, which is obtained by fitting a power law size‐frequency distribution to discovered mineral deposits in a given region, show concave‐down departure from the correlation line fitted. The authors suggest that the size and number of undiscovered deposits may be forecast by fitting a fractal size distribution to discovered mineral deposit sizes between the upper and lower truncation observations and then extrapolating the scale‐independent area to deposit sizes larger than the upper truncation limit. Based on the statistical results obtained by the fractal size‐frequency distributions of 394 discovered gold deposits with sizes greater than 2 t Au in China and 83 known gold deposits with sizes over 0.3 t Au in the Jiaodong area of China, the authors forecast according to the present commercial standards for gold ores that the total resources of undiscovered gold deposits ranging in tonnage from 50 to 2000 t Au are more than 4500 t in China, and that in the Jiaodong area of China the total resources of potential gold deposits with sizes in the range of 30 to 650 t Au are about 700 t.
Genetic Mechanism of Mineral Inclusions in Zircons from the Khondalite Series, Southeastern Inner Mongolia
Authors: Fulai LIU , Qihan SHEN
Published: September 2010

Abstract  The early Precambrian khondalite series is widely distributed in the Jining‐Zhuozi‐Fengzhen‐Liangcheng area, southeastern Inner Mongolia. The khondalite series mainly consists of sillimanite garnet potash feldspar (or two‐feldspar) gneiss and garnet biotite plagioclase gneiss. These gneissic rocks have commonly experienced granulite‐facies metamorphism. In zircons separated from sillimanite garnet potash feldspar gneisses, many mineral inclusions, including Sil, Grt, Ky, Kfs, Qtz and Ap, have been identified by the Laser Raman spectroscopy. Generally, prograde metamorphic mineral inclusion assemblages such as Ky + Kfs + Qtz + Ap and Ky + Grt + Kfs + Qtz are preserved in the core of zircon, while peak granulite‐facies metamorphic minerals including Sil + Grt + Kfs + Qtz and Sil + Grt + Kfs + Qtz + Ap are identified in the mantle and rim of the same zircon. However, in some zircons are only preserved the peak metamorphic minerals such as Sil + Grt + Kfs + Qtz and Sil + Grt + Kfs + Qtz + Ap from core to rim, and in others are inherited the primary cores with minor mineral inclusions of Kfs + Qtz, with peak metamorphic mineral inclusions around the inherited cores. These data indicate that the mineral assemblage evolution of sillimanite garnet potash feldspar gneisses in the study are did experience a polymorphic transformation of kyanite to sillimanite. In garnet biotite plagioclase gneisses, secondary electron microscopic images reveal that most zircons display distinct zoning textures, which comprise cores and rims, each with distinctive inclusion assemblages. The inherited mineral inclusions, mainly consisting of Kfs + Pl + Qtz, Kfs + Qtz and Kfs + Qtz + Ap, are preserved in the primary cores, while peak granulite‐facies mineral asemblages, including Grt + Bt + Pl + Qtz + Ap, Grt + Bt + Pl + Qtz and Grt + Bt + Pl + Qtz + Rt, are identified on the rims. The occurrence of peak metamorphic mineral inclusions in zircons indicates that these gneissic rocks, including sillimanite garnet potash feldspar gneiss and garnet biotite plagioclase gneiss, have experienced granulite‐facies metamorphism.

Secondary electron microscopic images of zircons from the khondalite series display distinct zoning from core to rim, and are genetically related to the primary, prograde, and peak metamorphic mineral inclusion assemblages respectively. These images reveal irregular zoning patterns and varying thickness of cores and rims. The abundance of inclusions complicates the conventional U‐Pb age dating. Therefore, the SHRIMP micro‐spot U‐Pb method is essential for the protolith and metamorphic age dating of the khondalite series, southeastern Inner Mongolia.
Models of Spatial Structures of Regional Multi‐element Geochemical Anomalies over Copper‐Polymetallic Orefields
Authors: Changyi SHI , Jinhua ZHANG
Published: September 2010

Abstract  Regional stream sediment surveys at a 1:200,000 scale reveal positive and negative regional multi‐element geochemical anomalies over medium to large copper‐polymetallic orefields of different genetic types in China. Regional geochemical anomalies of orefield refer to those geochemical anomalies that are related to metallogenesis of an orefield in a certain area. The anomaly area is typically 10 to 100 km2. The regional multi‐element anomalies related to mineralization can be divided into three groups, that is, the ore‐element anomaly association, indicator element anomaly association, and metallogenic environmental element anomaly association. Their common spatial distributions over ore deposits or orefields possess unique structures.

The model of spatial structure of regional multi‐element geochemical anomalies (RAGSS) of an orefield delineates structural feature possessed by orderly spatial distributions of different groups of multi‐element anomaly associations related to orefield metallogenesis. It is used to outline the common metallogenetic anomaly visage that is composed of the orderly spatial distribution of different groups of multi‐element anomaly associations. The orderly spatial distribution of multi‐element anomalies over an orefield reflects element distributions as they are changed from a dispersed “out‐of‐order” state into a concentrated “orderly” state during the mineralization of an orefield.

Three different patterns of the spatial anomaly structure related to mineralization in an orefield can be concluded: (1) nested pattern; (2) eccentric pattern and; (3) peripheral pattern. There are marked differences between multi‐element anomaly patterns related and not related to mineralization. RAGSS models of orefields can be used to better understand and evaluate regional multi‐element anomalies and identify ore types.
Quantitative Evaluation of the Sea‐level Drop at the End‐Permian: Based on Reefs
Authors: Yasheng WU , Jiasong FAN
Published: September 2010

Abstract  The amplitude of pre‐Quaternary sea level drop, H, can be calculated by using the formula H = D + To, where To is the original thickness from the top of the tidal deposits on the reef core to the bottom of the tidal deposits on the reef front, or to the bottom of the ancient meteoric vadose zone, or to the edge of the mixed‐water dolostone zone. The identity and similarity between the sea‐level drop amplitudes calculated from different reefs far away from each other indicates that such sea‐level changes are eustatic rather than relative changes. Evidence of an end‐Permian sea‐level drop has been found on the Changxingian (i.e. the end of the Palaeofusulina zone) reefs at Ziyun in South China, including algal laminated deposits, sabkha‐related dolostone, desiccation cracks, dissolution collapse breccia. According to calculation based on the meteoric dissolution zone of the reef‐core sequence at Ziyun, Guizhou province, the amplitude of the sea‐level drop at the end‐Permian is about 89.3 m. Calculation via the dolomitized upper part of the Changxingian reef in Lichuan, Hubei Province, yields an 88.9 m amplitude of the sea‐level drop at the end‐Permian. Comparison shows that the sea‐level drop recorded in the two distantly located reefs may be of eustatic type. So the amplitude of the sea level drop of the Tethys Sea at the end‐Permian might be at least 89.3 m.
A New Basal Titanosaur (Dinosauria: Sauropoda) from the Early Cretaceous of China
Authors: Hailu YOU , Feng TANG , Zhexi LUO
Published: September 2010

Abstract  A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria. Its finding also suggests that titanosaurs might have originated in Asia no later than the Early Cretaceous.
An Experimental Calibration on the Sphalerite‐Galena Sulfur Isotope Geothermometer
Authors: Tiping DING , Chengxin ZHANG , Defang WAN , Zhijian LIU , Guilan ZHANG
Published: September 2010

Abstract  A new experimental calibration was undertaken in this study to get a more reliable sphalerite‐galena sulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of natural hydrothermal solution. The high‐precision SF6 method was used in sulfur isotope analyses. The obtained calibration curve for sulfur isotope fractionation between sphalerite and galena can be expressed with the equation 10001nαSp‐Gn = 0.74times106T−2+0.08.
A Metallogenic Model of Gold Deposits of the Jiaodong Granite‐Greenstone Belt
Authors: Jun DENG , Liqiang YANG , Zhongshi SUN , Jianping WANG , Qingfei WANG , Hongbo XIN , Xinjun LI
Published: September 2010

Abstract  An analysis of trace elements and isotopic geochemistry suggest that the ore‐forming materials of gold deposits in the Jiaodong granite‐greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust‐mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono‐metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean‐Proterozoic—the embryonic form of Au‐source system; (2) stable tectonic setting in the Paleozoic—an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic—tectono‐mineralization and tectono‐diagensis; (4) posthumous structural activity in the Cenozoic—destruction of orebodies in the later stage. In the middle and late Indosinian, the Tancheng‐Lujiang fault zone cut deeply into the upper mantle so that the ore‐bearing fluids migrated to higher layers through the crust‐mantle interaction, resulting in alteration and mineralization.
40Ar/39Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh‐Pressure Metamorphic Rocks in Donghai, East China
Authors: Jinyi LI , Tiannan YANG , Wen CHEN , Sihong ZHANG
Published: September 2010

Abstract Recent investigations reveal that the ultrahigh‐pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile‐brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile‐brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite‐plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite‐facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 213.1 ± 0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K‐feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma, 203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K‐feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ages on the ultrahigh‐pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3–4 km/Ma from the mantle (about 80–100 km below the earth's surface at about 240 Ma) to the lower crust (at the depth of about 20‐30km at 220 Ma), and at the rate of 1–2 km/Ma to the middle crust (at the depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km deep at about 204 Ma.
Cenozoic Adakite‐type Volcanic Rocks in Qiangtang, Tibet and Its Significance
Authors: Shen LIU , Ruizhong HU , Caixia FENG , Xiaoguo CHI , Cai LI , Rihong YANG , Tianwu WANG , Wei JIN
Published: September 2010

Abstract Volcanic rocks in the study area, including dache, trachyandesite and mugearite, belong to the intermediate‐acid, high‐K calc‐alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in Al2O3 (15.09–15.64%) and Na2O (>3.6%), high Sr (649–885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg#<0.35), weak Eu anomaly (Eu/Eu*=0.84‐0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062‐0.7079, 143Nd/144Nd=0.51166‐0.51253, εNd = −18.61‐0.02), show that the magma resulted from partial melting (10%‐40%) of newly underplated basaltic lower crust under high pressure (1–4 GPa), and the pedogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.
Post‐collisional Adakitic Porphyries in Tibet: Geochemical and Sr‐Nd‐Pb Isotopic Constraints on Partial Melting of Oceanic Lithosphere and Crust‐Mantle Interaction
Authors: Yongfeng GAO , Zengqian HOU , Ruihua WEI , Rongsheng ZHAO
Published: September 2010

Abstract The distribution of Neogene felsic porphyries intruding in earlier granitic batholiths was mainly controlled by north‐south‐tending rifting zones and normal faults. The main rock types of the felsic porphyries include granodiorite‐porphyry, monzonitic granite‐porphyry and quartz monzonitic porphyry. The porphyries are characterized by high SiO2 (≥64.26%) and Al2O3 (>15% at 70% SiO2), low Y and HREE (Yb) contents, strong enrichment of LILE and LERR, especially K and Sr. Geochemical features of the porphyries show distinct adakitic magma affinity. Nd, Sr and Pb isotopic compositions of the porphyries form a linear alignment from MORB to EM2, suggesting a mixing of the MORB reservoir with the metasomatized mantle reservoir. Considering also the geochemical characteristics of the porphyries and the sequence of observable structural‐thermal‐magmatic events at Gangdise, it is thought that the Neogene porphyries were formed by partial melting of dead subducted oceanic crust in a post‐collision setting. K‐enrichment in the porphyries is attributed to the interaction of slab‐derived melts, i.e., adakites, with the metasomatized mantle during the ascent There might be a delamination of residual eclogites or amphibole eclogites before the eruption of potassic lava on the Tibetan plateau since 13 Ma.
Geochemical Behaviors of REE and Other Trace Elements during the Formation of Strata‐bound Skarns and Related Deposits: A Case Study of the Dongguashan Cu (Au) Deposit, Anhui Province, China
Authors: Qicong LING , Congqiang LIU
Published: September 2010

Abstract REE and other trace elements in the altered marbles, massive skarns and ores, as well as garnet and quartz were determined in order to examine the behaviors of trace elements during hydrothermal alteration. It is demonstrated that the high‐field‐strength (HFS) elements Zr, Hf, Th and Nb were immobile while other trace elements were mobile during the formation of skarns and related deposits. REE and ore‐forming elements such as Cu and Ag in hydrothermally‐altered marbles and skarns were provided primarily by hydrothermal fluids. In the direction transverse of the strata, the more deeply the marbles were altered, the higher the total REE abundance and the larger the negative Eu anomalies would be. The chondrite‐normalized REE patterns of skarns are similar to those of the marbles, but the former are distinguished by much higher REE contents and more remarkable negative Eu anomalies. Those patterns were apparently not inherited from the marble protolith, but were controlled by garnets, which were determined by the hydrothermal solutions involved in the infiltration metasomatism. The hydrothermal fluids are characterized by having slightly right‐hand dipping REE patterns, being enriched in LREE and having strongly negative Eu anomalies. The uptake of REE from hydrothermal fluids during the growth of garnet crystals resulted in the garnets having similar REE patterns to the hydrothermal fluids. Based on the spatial variation of REE in skarns and the structures of the hosting strata, we can get a better understanding of the transport path and pattern of the fluids involved in the formation of skarns and their related deposits. REE geochemistry investigation can help elucidate the genesis of skarns and skarn‐related deposits.
Giant Mineral Deposits and Their Geodynamic Setting in the Lanping Basin, Yunnan, China
Authors: Chunji XUE , Shuwen LIU , Yuchuan CHEN , Rong ZENG , Shihua ZHAO
Published: September 2010

Abstract  There are giant mineral deposits, including the Jinding Zn‐Pb and Baiyangping Ag‐Co‐Cu, and other important mineral deposits (e.g., Baiyangchang Ag‐Cu, Jinman Cu deposits, etc.) in the Lanping Mesozoic‐Cenozoic Basin, Yunnan Province, China. The tabular ore‐bodies and some veins hosted in terrestrial clastic rocks of the Mesozoic‐Cenozoic age and no outcropping of igneous rocks in the giant deposits lead to the proposal of syngenetic origin, but the giant mineral deposits are not stratabound (e.g. MVT, sandstone‐ and Sedex‐type). They formed in a continental red basin with intense crust movement. The mineralization is controlled by structures and lithology and occurs in different strata, and no sedimentary nature and no exhalative sediments are identified in the deposits. The deposits show some relations with organic matter (now asphalt and petroleum) and evaporates (gypsum). The middle‐low‐temperature (mainly 110°C to 280°C) mineralization took place at a depth of about 0.9 km to 3.1 km during the early Himalayan (58 to 67 Ma). The salinity of ore‐forming fluids is surprisingly low (1.6% to 18.0 wt% (NaCl)eq). Affected by the collision of the Indian and Eurasian plates, the mantle is disturbed under the Lanping Basin. The large‐scale mineralization is closely linked with the geodynamics of the crust movement, the mantle and mantle‐flux upwelling and igneous activity. Giant mineral deposits and their geodynamic setting are unique in the Lanping Basin.
Dating and Fluid Geochemistry of the Sarkobu Gold Deposit in Altay, Xinjiang, China
Authors: Rufu DING , Jingbin WANG , Lunshan ZHAO , Zhongmei MA , Jinhong ZHANG
Published: September 2010

Abstract  The dating of fluid inclusions of quartz yields an Ar‐Ar isochrone age of 320.4±6 Ma. Three types of fluid inclusions have been identified with the homogenization temperature ranging from 157°C to 362°C. The homogenization temperature consists of two groups. The first group varies from 157°C to 166°C, and the second from 232°C to 362°C. Their chemical composition is dominated by Na+‐Ca2+‐Mg2+ and Cl−. The relative concentration of ions is characteristic by Na+>Ca2+>K+>Mg2+ and Cl−SO42‐>F−. The δD and δ18O values indicate that the ore‐forming fluid originates from mixing of multi‐source water. The Sarkobu gold deposit has experienced two mineralization stages: gold was enriched during the volcanic‐exhalative‐sedimentary process in the early stage, while the gold deposit was finally formed under compression‐shearing during the orogenic period.
Remote Sensing Geological Exploration Model for Copper and Gold Deposits in the East Tianshan, Xinjiang
Authors: Shoulin ZHANG , Shuixing FU , Chunxia LI
Published: September 2010

Abstract Based on the identification and enhancive processing of information about strata, structure, magmatite, and alteration in ore‐concentrated area in the eastern Tianshan, an exploration mode of remote sensing geology is established. The mode covers basic images composed of TM (7, 4, 1), Munsell space transformation for recognizing rock type, directional matched filtering for enhancing structures, multi‐layer separating and extracting weak alteration information. It will provide a rapid and effective method for geological mapping and metallogenic prediction in this region.
Dating of the Dachang Superlarge Tin‐polymetallic Deposit in Guangxi and Its Implication for the Genesis of the No. 100 Orebody
Authors: Denghong WANG , Yuchuan CHEN , Wen CHEN , Haiqing SANG , Huaqin LI , Yuanfa LU , Kaili CHEN , Zhimao LIN
Published: September 2010

Abstract  The Dachang superlarge Sn‐polymetal deposit in Guangxi, China, is one of the largest tin deposit all over the world. However, this deposit has long been in debate as to its origin. One of the opinions is that the Dachang deposit was formed by replacement of hydrothermal solution originating from Yanshanian granites, and the other is that this deposit was formed by submarine exhalation in the Devonian. This paper presents some new isotopic geochronology data obtained with the 40Ar‐39Ar method for quartz and sanidine from massive ore in the No. 91 and No. 100 orebodies. Analytic results show that the No. 91 orebody was formed at 94.52±0.33 Ma (the plateau age obtained with the 40Ar‐39Ar method for quartz) or 91.4±2.9 Ma (the plateau age obtained with the 40Ar‐39Ar method for feldspar), while the No. 100 orebody was formed at 94.56±0.45 Ma (the plateau age obtained with the 40Ar‐39Ar method for quartz), suggesting that both the No. 91 and the No. 100 orebodies were formed at the Late Yanshanian instead of the Devonian. The No. 100 orebody might be formed by filling of ore materials into caves in Devonian reef limestone. Because the ore‐bearing solution released its pressure and lowered its temperature suddenly in a cave environment, ore minerals were formed concentratedly while water and other materials such as CO2 evaporated quickly, resulting less alteration of host rocks.
He‐Ar Isotopic Systematics of Fluid Inclusions in Pyrites from PGE‐polymetallic Deposits in Lower Cambrian Black Rock Series, South China
Authors: Xiaoming SUN , Min WANG , Ting XUE , Mingyang MA , Yinhe LI
Published: September 2010

Abstract  He‐Ar isotopic compositions of fluid inclusions trapped in pyrites from some representative PGE‐polymetallic deposits in Lower Cambrian black rock series in South China were analyzed by using an inert gas isotopic mass spectrometer. The results show that the ore‐forming fluids possess a low 3He/4He ratio, varying from 0.43×10−8 to 26.39×10−8, with corresponding R/Ra value of 0.003‐0.189. The 40Ar/36Ar ratios are 258–287, close to those of air‐saturated water (ASW). He‐Ar isotopic indicator studies show that the ore‐forming fluids were mainly derived from the formation water or basinal hot brine and sea water, while the content of mantle‐derived fluid or deep‐derived magmatic water might be negligible. The PGE‐polymetallic mineralization might be related to the evolution of the Caledonian miogeosynclines distributed along the southern margin of the Yangtze Craton. During the Early Cambrian, the formation water or basinal hot brine trapped in Caledonian basins which accumulated giant thick sediments was expelled and migrated laterally along strata because of the pressure generated by overlying sediments. The basinal hot brine ascended along faults, mixed with sea water and finally deposited ore minerals.
Fluid Inclusions of Orogenic Gold Deposits in the Zhongchuan Area, Western Qinling and Their Geological Significance
Authors: Zuoheng ZHANG , Jingwen MAO
Published: September 2010

Abstract  Orogenically‐derived gold deposits of the Zhongchuan area in the western Qinling are distributed in the exocontact thermal metamorphic zone. The country rocks hosting the deposits are predominantly of Devonian age with low‐grade metamorphism and strong deformation with the ore deposits directly controlled by multi‐level tectonic systems. Three types of inclusions from these deposits have been recognized: CO2‐H2O, CO2‐rich, and aqueous. The ore‐forming fluids were mainly CO2‐NaCl‐H2O type characterized by rich CO2, low salinity, high temperature and immiscibility. Incorporated with earlier isotopic data, the regional geological setting and features of diagenesis and metallogeny, it can be concluded that the ore‐forming fluids were derived from deep magma and mixed with meteoric and metamorphic water. The deposits formed during an intra‐continent collisional orogeny, and some of the materials derived from the deep might have been involved in the ore‐forming process.
Pb‐Zn‐Ag‐bearing Manganoan Skarns of China
Authors: Yiming ZHAO , Daxin LI
Published: September 2010

Abstract  Manganoan skarns consist of special Mn (Ca, Mg, Fe, Al) silicate metasomatic minerals and are usually associated with Pb‐Zn(Ag) mineralization. They occur chiefly along the lithologic contacts or faults and fractures of carbonate wall rocks distal from the intrusive contact zone, and are combined with Fe, Cu, W, Sn and Cu‐bearing calcic or magnesian skarns occurring in the contact zones to constitute certain metasomatic zoning. Manganoan skarns are formed later than calcic or magnesian skarns. Their rock‐forming temperatures are lower than those of calcic or magnesian skarns. The mineral assemblages of manganoan skarns occurring in different carbonate rocks (limestone or dolomite) are notably different.
Mixed Population Screening for Sulfur Isotopes
Authors: Bin CUI , Lei ZHAO , Zhaoyang ZHAN , Zhijun HE
Published: September 2010

Abstract  Quantitative research of the origin of sulfur isotopes is a difficult problem that has puzzled geochemists all along. In the study of the middle and lower reaches of the Yangtze River and the Dongpo orefield in Hunan Province, the authors successfully applied the mathematical model of mixed population screening to quantitatively resolving the problem on the origin of sulfur isotopes, which is significant in finding out the source of mineralizing matter and metallogenic mechanisms.
Trend of Salt Lake Changes in the Background of Global Warming and Tactics for Adaptation to the Changes
Authors: Mianping ZHENG , Wen QI , Xianfeng JIANG , Yuanyi ZHAO , Minghui LI
Published: September 2010

Abstract  Salt lakes are a mirror of climatic changes and provide holographic records of environmental changes of lakes. According to a study of geological hazards in typical salt lake areas in China and other regions, the authors explain how geological hazards in salt lake areas are caused by natural agents and how humans can seek benefits, avoid hazards and reduce losses on the premise that they have monitored and mastered the trend of salt lake changes in advance and even can store flood and recharge water in lakes and extract saline resources. The climate in western China is probably turning from warm‐dry to warm‐moist. The authors analyze the change trend of salt lakes sensu lato (with salinity≥0.3 wt% (NaCl)eq) and salt lakes sensu stricto (with salinity ≥3.5 wt% (NaCl)eq) in China in such climatic conditions and distinguish three types of salt lake areas (i.e. lake water rising type, lake water falling type and lake water rising and unstable type) according to the characteristics of lake water rising and shrinking. In order to conform to the climatic and lake changes in China's salt lake areas, the authors propose to add and improve hydrological and meteorological observation stations and integrate observations with remote sensing monitoring in important salt lake areas and set up multidisciplinary and interdepartmental basic projects to monitor and study recent climatic and environmental changes in salt lake areas of western China. Moreover, it is necessary to build additional flood‐control and drought‐preventing water conservancy facilities in key salt lake areas and work out measures for ecological protection in salt lake areas. Full consideration should be given to the influence of flooding when building saltfields and implementing capital projects.
Analysis of the Geomorphology and Environmental Geological Problems of Huzhou on the Yangtze River Delta
Authors: Yuehua JIANG , Jingdong WANG , Xueyin YUAN , Runhua WANG
Published: September 2010

Abstract  Geomorphically, Huzhou, which is on the Yangtze River delta is characterized mainly by plains, with small hills. This paper presents a detailed analysis of the environmental geological hazards both natural and those incurred by human activities in different morphologic units. The authors point out that most of the regional environmental geological problems in the natural geologic‐morphologic conditions, such as crustal stability, foundation of soft soil, soil waterlogging and soil erosion, have insignificant effects to the society, or related countermeasures of prevention and control have been adopted. But environmental geological problems incurred by human being's economic activities become more and more severe, for example, water and soil pollution and land subsidence in plain areas resulting from overexploitation of groundwater, and landslides, karst collapses and water and soil loss etc. caused by quarrying in hilly areas.
Mangshan Loess in Central China and the Paleomonsoon Variations since the Last Interglaciation
Authors: Fuchu JIANG , Shubing WANG , Zhizhong ZHAO , Jianli FU
Published: September 2010

Abstract  The Mangshan Yuan is a loess platform on the southern bank of the Yellow River, which is located in northwestern Zhengzhou of Henan Province, China. The typical Zhaoxiayu section of the Mangshan Yuan preserves stratigraphical loess units above S10 with a total thickness of 172.1 m, which includes 15.7 m of the last interglacial paleosol S1, 77.3 m of the last glacial loess L1 that consist of 41.6 m of the late stade L1LL1, 13.2 m of the interstade L1SS1 and 22.5 m of the early stade L1LL2. Based on the age marking points by correlating magnetic susceptibility of the section with the SPECMAP curve, the timescale of the section was constructed, and the average accumulation rate and the resolution of each loess strata over the S2 were subsequently calculated using the susceptibility age model. The results indicate that strata units developed in the glacial, interglacial stages, stadial and interstadial show substantial differences in grain size, average accumulation rate and time resolution ub the Zhaoxiayu section. Specifically, the average accumulation rate of the loess L1LL1 is 3.45 mm/a, whereas that of paleosol S1 is only 0.28 mm/a. Based on the high‐resolution records of magnetic susceptibility and >45 μm fraction percentage of the loess‐paleosol, the summer and winter monsoon variations as well as their interrelations since the last interglaciation have been discussed, which were correlated with the SPECMAP and the GRIP climate records.
Degradation Kinetics of Petroleum Contaminants in Soil‐Water Systems
Authors: Xilai ZHENG , Bingchen WANG , Yuying LI , Wenxiang XIA
Published: September 2010

Abstract  On the basis of site investigation and sample collection of petroleum contaminants in the soil‐water‐crop system in the Shenyang‐Fushun sewage irrigation area, the physical‐chemical‐biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long‐term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes. After a 110‐days' biodegradation test, the degradation rate of residual oil is 9.74%–10.63%, while the degradation rate of aqueous oil reaches 62.43%. This indicates that the degradation rate of low‐carbon aqueous oil is higher than that of high‐carbon residual oil. In addition, although microbial degradation of petroleum contaminants in soils is suitable to the first‐order kinetics equation, the half‐lives of aqueous oil, No. 20 heavy diesel and residual oil in the surface soils (L2–1, S1–1 and X1–1) are 1732 h, 3465 h and 17325 h, respectively.
Three‐Dimensional Gravity Model Applied to Underwater Navigation
Authors: Lei YAN , Hao FENG , Zhongliang DENG , Zhengbing GAO
Published: September 2010

Abstract At present, new integrated navigation, which usesthe location function of reference gravity anomaly map to control the errors of the inertial navigation system (INS), has been developed in marine navigation. It is named the gravity‐aided INS. Both the INS and real‐time computation of gravity anomalies need a 3‐D marine normal gravity model. Conventionally, a reduction method applied in geophysical survey is directly introduced to observed data processing. This reduction does not separate anomaly from normal gravity in the observed data, so errors cannot be avoided. The 3‐D marine normal gravity model was derived from the J2 gravity model, and is suitable for the region whose depth is less than 1000 m.
Model of Reflection Spectra of Rock Surface in 2π Space
Authors: Hongying ZHAO , Hu ZHAO , Lei YAN , Yunsheng ZHAO
Published: September 2010

Abstract  This paper deals with reflection spectra and polarized reflection spectra of 20 sorts of rock in 2π space, and then creates a model of reflection spectra of rock surface in 2π space. We measured the change of reflection and polarized reflection spectra as altering the incidence angle, vertex angle, azimuth angle, band and polarization. The results show that influence of the incidence angle on spectral curves is very strong. And when the vertex angle is constant, the horizontal azimuth polarizes rock spectra, and distorts the circular spectrum to become elliptic. The polarization influences the reflection intensity of rock spectra, but has no evident influence on the characteristics of wave forms of rock in 2π space. Therefore, we can describe the whole reflection spectral characteristics, including polarization, of rock surface in 2π space by measuring and calculating the e and p values in several key directions.
Early Cooling History of Eclogites from the Dabie‐Sulu Orogen: Constraints from Diffusion Kinetics of Garnet
Authors: Daogong CHEN , Hao CHENG
Published: September 2010

Abstract  For the first time, we apply different geospeedometric models to garnet zoning patterns that were obtained in this study from detailed EMP analyses for garnets from eclogites and granulite in the Dabie‐Sulu orogen. Various zonings of cation diffusion were preserved in the garnets, enabling the acquirement of average cooling rates for the high‐to ultrahigh‐pressure rocks without using geochronological approaches. The coesite‐bearing hot eclogites yield fast cooling rates of about 20 to 30°C/Ma subsequent to peak metamorphic temperatures, whereas the cold eclogite gives a relatively slow cooling rate of 8°C/Ma at its initial exhumation. A very slow cooling rate of <0.3°C/Ma is obtained for the granulite at Huangtuling, suggesting that the granulite may not be involved in the continental deep subduction.
Zr, Hf, U, Th and REE‐Fertile Lower Proterozoic Potassic Granite from Parts of Andhra Pradesh, South India
Authors: SINGH Yamuna
Published: September 2010

Abstract The medium‐ to coarse‐grained and porphyritic granitoid of Dharmawaram, Karimnagar district, Andhra Pradesh, south India is a biotite‐hornblende granite with notable contents of rare metal (Zr, Hf, Th) and rare earth (including Y) minerals like zircon, thorite, allanite, monazite and xenotime. Chemically, it is metaluminous (average A/C+N+K = 0.95)‐type, potassic (av. 5% K2O) granite, with dominantly sub‐alkaline characters. It shows up to 8 times enrichment of rare metals (Zr, Hf, U, Th) and rare earths (including Y, Sc), with reference to their abundances in normal unevolved granite, and hence, fertile for some of these elements. Field, petrological, geochemical and isotopic data of potassic granite (PG) indicate involvement of silica‐rich metasedimentary‐basic crustal rocks (amphibole‐quartzite, amphibolite, hornblende‐biotite gneiss, etc.) in its genesis, at a depth range of 30 km. Further, chondrite‐normalized REE patterns demonstrate that low‐degree partial melting of source rocks is the major controlling factor in the genesis of PG. Mild negative Eu‐anomaly (av. Eu/Eu* = 0.48), plots of Ba‐Rb‐Sr in the field of anomalous granite and K/Rb ratios (av. 239) in the range that is shown by normal unevolved granite together indicate less fractionated nature of the PG. Limited fractionation of metalumination‐type, involving hornblende, led to occasional weak alumina saturation. Interestingly, geochemical and petrogenetic features of the studied PG broadly match with those potassic granites which are already known to host anomalously high enrichment of rare metals and rare earths in other parts of Andhra Pradesh and adjoining Karnataka.
Three Stages of Mesozoic Bimodal Igneous Rocks and Their Tectonic Implications on the Continental Margin of Southeastern China
Authors: Guangfu XING , Zhuliang YANG , Rong CHEN , Jialin SHEN , Naiyi WEI , Yuzhang ZHOU
Published: September 2010

Abstract There are large‐scale Mesozoic bimodal igneous rock associations on the continental margin of southeastern China. They aroused extensive attention in the 1980s because of their specific tectonic implications, and have been found frequently during recent geological surveys. This paper reviews the studies of regional Mesozoic bimodal rocks, and concludes that they can be subdivided into three stages, i.e., the Early Jurassic (209–170 Ma, the first (I) stage), the Late Jurassic–early Early Cretaceous (154–121 Ma, the second (II) stage), and the late Early Cretaceous–Late Cretaceous (115–85 Ma, the third (III) stage). These three stages of bimodal rocks were formed in different tectonic settings, and are important indicators for regional Mesozoic tectonic evolution.