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Liu P.-D.,Henan Institute of Geological Survey
Northwestern Geology | Year: 2014

Laobing gypsum magnetite deposit, a new deposit type, is located in the west side of Ta'axi major fracture. This article is based on the newest investigation results and the analysis a- bout the mining area geology as well as ore deposit geology. Then we get the conclusion about the mineralization process of Laobing gypsum magnetite deposit; the submarine volcanic activities brought a lot of hot solution with salt and metallic solution to form the ore-bearing solution who transferred by the driving of Eh and pH value discrepancy, then under certain physicochemical conditions, iron would precipitate and form magnetite. Meanwhile, interaction between the hot ore-bearing solution and the seawater provided sulfur for anhydrite, thus the symbiosis of gypsum and magnet happened. This phenomenon would help us to deepen understanding about the West Kunlun metallogenic belt and summarize the regional metallogenic regularity.

Wang G.,China University of Geosciences | Zhang S.,China University of Geosciences | Yan C.,China University of Geosciences | Yan C.,Henan Institute of Geological Survey | And 4 more authors.
Computers and Geosciences | Year: 2011

In this paper, we used 3D modeling and nonlinear methods (fractal, multifractal, and probabilistic neural networks (PNN)) for regional mineral potential mapping and quantitative assessment for porphyry and skarn-type Mo deposits and hydrothermal vein-type Pb-Zn-Ag deposits in the Luanchuan region, China. A 3D geological model was constructed from various geological maps, cross sections, boreholes, and gravity and magnetic data. Geological features associated with mineralization were extracted using the 3D geological model and metallogenic models of porphyry and skarn-type Mo and Pb-Zn-Ag deposits. The multifractal method, principal component analysis, and power spectrum-area method were used to separate regional variability from local variability in the geochemical data. A 2.5D forward modeling of gravity and magnetic data was carried out to define the geometry, depth, and physical properties of geological bodies at depth. 3D visualization of the results assisted in understanding the spatial relations between the deposits and the other geological bodies (e.g., igneous intrusions). The PNN method was applied to represent and integrate multiple anomalies for mineral potential modeling. The concentration-area fractal method was used to classify the PNN mineral potential model. Three levels (ground surface and two subsurface horizontal planes) of mineral potential models were evaluated for undiscovered Mo and Pb-Zn-Ag deposits. Validation of the results shows that 3D modeling was useful for not only accurately extracting geological features but also for predicting potential mineral targets and evaluating mineral resources. The mineral potential targets identified consist of eight Mo potential targets and 15 Pb-Zn-Ag potential targets. Based on grade-tonnage data from the known Mo and Pb-Zn-Ag deposits and the results of 3D modeling, estimated potential resources of each of these types of deposits are 10.8 and 153.1. Mt (Pb+Zn is 152.9. Mt and Ag is 0.92. Mt), respectively. © 2011 Elsevier Ltd.

Wang G.,China University of Geosciences | Zhu Y.,China University of Geosciences | Zhang S.,China University of Geosciences | Yan C.,Henan Institute of Geological Survey | And 5 more authors.
Journal of Applied Geophysics | Year: 2012

Three-dimensional (3D) geological modeling is an important method for understanding geological structures and exploring for mineral deposits. The Luanchuan super-large molybdenum polymetallic ore region has a complex geological setting and multiple metallogenic types. 3D geological modeling is implemented by combining geological knowledge with gravitational and magnetic data inversion in the study area. The 3D geological modeling methodology and the results are summarized as follows. (1) Based on the geological setting and the deposits/occurrences, the aim was to constrain and determine the main geological objects in 3D space to construct geological and metallogenic models. (2) Based on geological observations and rock physical measurements to derive qualitative information about geological objects at depths using gravitational and magnetic data inversion, 2.5D forward modeling was used to identify shallow/subsurface geological objects, and the 3D probability method of potential field inversion was used for coarse constraining of geological objects at depths. (3) A combination of geological information with gravitational and magnetic data inversion information was used to determine the space-time genesis of metallogenic objects in potential mineral targets (i.e., Late Jurassic granite intrusions, ore-forming strata, and ore mineralization favorable faults). (4)A 3D model of the study area (17.7. km. ×. 12.0. km. ×. 2.5. km) is associated with the surface and subsurface geological data, which has geophysical information that is beneficial for identifying and evaluating potential prospecting zones. © 2012 Elsevier B.V..

Wang G.,China University of Geosciences | Zhang S.,China University of Geosciences | Yan C.,China University of Geosciences | Yan C.,Henan Institute of Geological Survey | And 4 more authors.
Journal of Applied Geophysics | Year: 2012

Fractal and multifractal scaling can be found in a wide variety of geological, geochemical and geophysical applications, which provide important clues to underlying processes. In this study, the multifractal singular value decomposition (MSVD) method was used to delineate geophysical anomalies associated with Mo mineralizations based on 1:25,000 scale gravity and magnetic data in the Luanchuan super-large molybdenum polymetallic ore district. The results show that: (1) negative gravity anomalies in the Luanchuan ore field have strong spatial relationships with Jurassic granite porphyry bodies associated with porphyry- and skarn-type Mo mineralizations; (2) the uncertainty linked with identifying gravity and magnetic anomalies' areas is correlated with cutoffs defined in the multifractal models, which can be utilized to recognize potential Mo mineralization at depths ranging from 500. m to 2000. m; and (3) positive magnetic anomalies have weak spatial correlations with Jurassic granite porphyry bodies, but are strongly correlated with gabbro and syenite porphyries associated with Fe mineralization, and with the boundary of Jurassic granite porphyry. Compared to the 3-D Jurassic granite porphyry model and the 2.5-D gravity and magnetic inversion plots of the study area, the gravity and magnetic anomalies identified by means of the MSVD method can be integrated to identify potential Mo targets. This application demonstrates that the MSVD method is convenient, simple, rapid, and direct for delineating geophysical anomalies and for outlining potential exploration targets without processing multiple geological, geophysical, and geochemical datasets from disparate sources. © 2012 Elsevier B.V.

Li D.,China University of Geosciences | Zhang S.-T.,China University of Geosciences | Yan C.-H.,China University of Geosciences | Yan C.-H.,Henan Institute of Geological Survey | And 5 more authors.
Journal of Geodynamics | Year: 2012

Two late Mesozoic granitoids in the Luanchuan area of the East Qinling orogen are considered; ore-bearing rocks are granite porphyries and granodiorite, with K 2O>Na 2O, appearing in the form of stocks. The Laojunshan rocks contains dominantly monzonitic granite, with K 2O≈Na 2O, in the form of a batholith. Both the ore-bearing rocks and the Laojunshan rocks are highly siliceous and shoshonitic, high-K calc-alkaline, similar to some I-type granites. Light rare earth elements (LREEs) are enriched in both rock suites, although the Luanchuan ore-bearing granitoids have higher concentrations, with (La/Yb) N ratios twice that of the barren Laojunshan granite suite. Ore-bearing rocks have, therefore, undergone greater fractionation of heavy rare earth elements. All Laojunshan rocks have negative Eu anomalies, indicating plagioclase fractionation. δEu values are different in both rock suites, the values in the ore-bearing granites, ranging from 0.52 to 1.04, which are much higher than that of Laojunshan batholith, ranging from 0.4 to 0.65. (La/Sm) N values of ore-bearing granites are 5.32-8.28, while that of Laojunshan batholith are 3.75-5.77, confirming the observation that the ore-bearing granites have undergone a higher degree of strong differentiation than that of Lanjunshan batholith.Major and trace element data, and REE data, combined with isotope data from previous work and the close relationships between the tectonic settings of the barren and ore-bearing rocks indicate that both groups of rocks were derived from the lower crust. At ∼157. Ma, with the tectonic regime in transition from a syn-collisional to a post-collisional setting, highly fractionated granites ascended from their storage area via faults; at ∼145. Ma, ore-bearing plutons, which are triggered by slab melts, formed at the junctions of fault planes trending WNW-ESE and NE-SW. At ∼115. Ma, the tectonic regime changed from compression to extension; in this environment, the barren Laojunshan batholith was emplaced, representing the end of the collisional event. © 2012 Elsevier Ltd.

Zuo J.-X.,Wuhan University | Zuo J.-X.,Henan Institute of Geological Survey | Tong J.-N.,Wuhan University | Zhao L.-S.,Wuhan University | And 2 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2013

Results of chemical analysis on rock samples collected from the north Pingdingshan Section, Chaohu, Anhui Province, Southeastern China, suggest that main elements of SiO2, Al2O3, Fe2O3, FeO, MgO, Na2O, K2O, TiO2, P2O5 and trace elements of Ba, V, Be, Nb, Zn, Cu, Ni, Co, Pb are rich in the Griesbachian, the Dienerian, as well as in the Smithian Subseries in the Lower Triassic. Eight distinct positive anomalies have been identified in the Lower Triassic on the basis of results of main and trace elements mentioned above. In ascending order, strength, size of anomalies and content of these elements in the Lower Triassic decrease gradually. In contrast to these elements, Sr and CaO are relatively concentrated in the Spathian subseries in the uppermost part of the Lower Triassic. Furthermore, trace element of Sr and main element of CaO enrich gradually up the north Pindingshan Section. Content of the former elements has negative correlation with δ13C values of carbonate, while the content of the later elements is positively related with δ13C values of carbonate. Commonly, δ13C value is used as an indicator of marine primary production and also used as an indicator to define restoration of marine ecological environment. Negative correlation between element contents and δ13C values indicates that the deteriorating marine environment is the tremendous disaster to the Early Triassic marine fauna in the Lower Yangtze region, while the positive correlation between element contents and δ13C values present that the feasible marine environment to the Early Triassic fauna. Eight marine geo-events have been identified in the Early Triassic based on the pronounced anomalies of trace elements and main elements. Strength of these events became weaker and weaker from the early Early Triassic to the late Early Triassic. A plenty of trace elements from the terrestrial volcano eruptions fluxed into the sea during the Late Permian and the Early Triassic, resulting in high content of argillaceous minerals and high grade of trace elements which led to paleocean environment deteriorating. Marine environment recovered as soon as the superfluous trace elements and argillaceous minerals deposited on the sea floor after volcano activities ceased.

Bao Z.,CAS Guangzhou Institute of Geochemistry | Wang Q.,CAS Guangzhou Institute of Geochemistry | Du F.,Henan Institute of Geological Survey
Chinese Journal of Geochemistry | Year: 2011

The Longwangzhuang granite pluton occurs on the southern margin of the North China Craton and consists mainly of biotite syenogranite with aegirine granite being locally distributed. The granites are characterized by high silicon and alkaline contents (SiO2=72.17%-76.82%, K2O+Na2O=8.28%-10.22%, K2O/Na2O≫1), AI (agpaitic index) =0.84-0.95, DI=95-97, ASI (aluminum saturation index)=0.96-1.13, and very high Fe* number (FeO*/(FeO*+Mg)=0.90-0.99), thus the granites are assigned to the metaluminous to weakly peraluminous, alkalic to calc-alkalic ferroan A-type granites. The granites are rich in large ion lithophile elements (LILE), especially high in REE concentrations (REE+Y=854×10-6-1572×10-6); whereas the enrichment of high strength field elements (Nb, Ta, Zr, Hf) is obviously less than that of LILEs, exhibiting mild depletions on trace element spider plots; and the rocks are significantly depleted in Ba, Sr, Ti, and Pb. The low εNd(t) values (-4.5- -7.2) and high model ages (2.3-2.5 Ga) of the granites as well as the low εHf(t) values (-1.11- -5.26) and high Hf model ages (THf1= 2.1-2.3 Ga, THf2=2.4-2.6 Ga) of zircons from the biotite syenogranite suggest that the granites were probably derived from an enriched mantle source. The zircons from the biotite syenogranite are mainly colorless transparent crystals exhibiting well-developed oscillatory zoning on the cathodoluminescence images with a LA-ICPMS zircon U-Pb age of 1602.1±6.6 Ma (MSWD=0.48). Petrochemical, trace elements, as well as Nd and Hf isotopic compositions of the rocks demonstrate that the granites were formed in a within-plate extensional tectonic regime possibly related to the breakup of the Columbia supercontinent. The granites were most likely formed through extreme fractional crystallization of alkali basaltic magma resulted from partial melting of the mantle, which was fertilized by recycling crustal rocks triggered by the delamination of lithospheric mantle and lower crust following the ~1.8 Ga collision and amalgamation of the North China Craton which is part of the Columbia supercontinent. However, contamination of neo-Archean to Paleoproterozoic crustal rocks during the ascent and emplacement of the magma could not be excluded. Being the youngest known anorogenic magmatism on the southern margin of the North China Craton related to Columbia breakup, it might represent the break off of the North China Craton from Columbia supercontinent at the end of Paleoproterozoic. © 2011 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.

Bian Y.-M.,Henan Institute of Geological Survey | Yu J.,Chinese Academy of Geological Sciences | Shao Z.-G.,Chinese Academy of Geological Sciences | Han J.-E.,Chinese Academy of Geological Sciences | He C.-G.,Chinese Academy of Geological Sciences
Acta Geoscientica Sinica | Year: 2013

Based on an analysis of Sporopollen assemblages of fluvial-lacustrine sediments in Paiku Co basin of Tibet since late Pleistocene, the authors divided the climate evolution into seven stages as follows: During 127-72 ka B.P, the climate was warm and humid, and broad-leaved and coniferous mixed forests constituted the main vegetation here. Between 66 ka B.P and 56 ka B.P., the climate turned into warm and dry, and the vegetation changed into wood grassland. During 56-49 ka B.P., the climate was characterized again by wetness and warmness and broad-leaved and coniferous mixed forest-dominated forest steppe. From 49 to 46 ka B.P., the climate was temperate and dry, and the vegetation turned into wood grassland. Between 46 and 31 ka B.P, the basin had a cool and wet climate, and the wood grassland here was in a lower temperature environment. During 31-15 ka B.P., the climate turned into cold, and the vegetation displayed alpine grassland. Since 11 ka B.P, the climate here has turned from warm and dry to cool and wet, and the vegetation has changed from bushveld into forest bushveld. It is thus concluded that the climate and environment in this region have experienced several evident cold-warm and dry-humid fluctuations in the general trend of gradually becoming arid.

Gao Y.-M.,Chinese Academy of Geological Sciences | Chen Y.-C.,Chinese Academy of Geological Sciences | Tang J.-X.,Chinese Academy of Geological Sciences | Li X.-F.,Henan Institute of Geological Survey | And 2 more authors.
Geological Bulletin of China | Year: 2011

Located in the Gongbo'gyamda County of Tibet, the Yaguila Pb-Zn, Mo deposit is a porphyry Mo skarn-hydrothermal vein type deposit occurring in the eastern part of the Gangdise belt. For the purpose of finding out the mineralization time of the porphyry type molybdenum deposit in the Nianqingtanggula mineralization belt, the authors selected five molybdenite samples from the Yaguila ore district to perform the Re-Os dating. The Re-Os dating yielded weighted average model ages of (64.27 ±0.9) to (65.97±1.13) Ma, varying in a narrow range, and an isochrone age of 65.0±1.9Ma (MSWD=3.2). It is proved that the porphyry type molybdenum deposit of the Yaguila ore district was formed during Early Eocene. The results indicate that there occurred large scale ore-forming processes during the main Indian-Asian collision period in the Gangdise belt.

Peng S.,CAS Nanjing Institute of Geology and Palaeontology | Zhu X.,CAS Nanjing Institute of Geology and Palaeontology | Zuo J.,Henan Institute of Geological Survey | Lin H.,CAS Nanjing Institute of Geology and Palaeontology | And 2 more authors.
Acta Geologica Sinica | Year: 2011

This paper briefly summarizes an officially ratified Global Standard Stratotype-section and Point (GSSP) and a proposed GSSP for global stages of the Cambrian System. The Luoyixi section near Luoyixi town, Guzhang, northwestern Hunan is ratified as the boundary stratotype for the base of the global Guzhangian Stage, which is the upmost stage of an unnamed series termed provisionally as Cambrian Series 3. The GSSP position lies 121.3 m above the base of the Huaqiao Formation in the section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Lejopyge leavigata. The Duibian B section at Duibian village, Jiangshan, western Zhejiang, is proposed as the boundary stratotype for the base of the proposed global Jiangshanian Stage that is the second stage of the Furongian Series. The proposed GSSP position lies 108.12 m above the base of the Huayansi Formation in the section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalius. This horizon is also with the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimhata.

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