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Yang H.-L.,Northwest Nonferrous Metals Party of Geophysical and Geochemical Exploration | Wang R.-T.,Northwest Mining and Geological Exploration Bureau for Nonferrous Metals | Zheng Q.,Northwest Nonferrous Metals Party of Geophysical and Geochemical Exploration | Meng D.-M.,Changan University
Northwestern Geology

The Meizipu gold deposit in Ankang of Shaanxi province is located in the southern margin of Niushandi anticline, Caledonian North-Daba mountain fold belt, Qinling fold belt. The geochemical anomalies are re-delineated through soil regular network geochemical measurements. Results indicate that the anomalies of Au, Ag, Cu, Pb, As, Sb, Bi are obvious, and there are good correlations among Au, Ag and Pb, as well as As, Sb and Bi. Spatial distribution characteristics analysis of anomaly elements reflects that the ore-forming fluid or hydrothermal fluids migrated from southeast to northwest. The validation and analysis of key anomalies confirm that the combination of anomaly, mica-quartz schist and east-north schistosity structure is the indicator for deposit of gold mineralization enrichment area. In addition, geological structure and magmatic activity are ore-controlling factors. The clear combination of Au, As, Pb, Ag, Sb elements and the obvious accumulation center indicate that the anomaly is mineralized anomaly. The soil anomalies of Mt-2, Mt-4 and Mt-5 are the potential exploration region in this area. Characteristics of geochemical anomaly indicate that the denudation of east is stronger than west. Therefore, it can be speculated that concealed ore body of gold may exist in western area, and there is a great prospecting potential. Source

Yuan H.,Northwest Nonferrous Metals Party of Geophysical and Gcochemical Exploration | Wang R.,Northwest Mining and Geological Exploration Bureau for Nonferrous Metals | Wang R.,Changan University | Li W.,No. 712 Party of Northwest Geological Exploration and Mining Bureau for Nonferrous Metals | And 2 more authors.
Northwestern Geology

The Jinduicheng superlarge molybdenum deposit is located at western Henan fracture-uplift area of the southern margin of North China platform Same as the Shijiawan, Dashigou, Wcngongling and Qin- linggou deposits, the Jinduicheng deposit is situated in the outside contact zone of Jinduicheng-Huanglongpu molybdenum ore fields. The formation of this deposit has close relationship with multiple sets of structure and porphyry body. The forms of ore body are basically identical as the ones of rock mass, but the ore body has branch phenomenon and its ore grade will be change from rich to poor as far from the rock mass. When the ore body is far away from the rock mass 600 meters, no mineralization occurred in wall rock, but some lead (silver) ore and gold ore bodies can be found there. Therefore, this deposit has a classical porphyry molybdenum metallogenic model. The differences and changes about geological characteristics of this deposit on longitudinal and latitudinal gradients will provide an important guiding significance for deep prespecting of the other molybdenum bodies in the outside contact zone of Ixioniushan rock mass. Source

Qiugen L.,Key Laboratory ofOrogenic Belts and Crustal Evolution | Qiugen L.,Chinese Academy of Geological Sciences | Shuwen L.,Key Laboratory ofOrogenic Belts and Crustal Evolution | Zongqi W.,Chinese Academy of Geological Sciences | And 4 more authors.
Acta Geologica Sinica

The Zhashui-Shanyang district is one of the most important sulfide deposits in the Qinling Orogen where the formation of porphyry-skarn Cu-Mo deposits has a close genetic link with the Yanshannian magmatism. Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb zircon dating of two granodiorite intrusions (Xiaohekou and Lengshuigou deposits) was investigated in the Zhashui-Shanyang district and the rock-forming ages obtained from 148.3±2.8 to 152.6±1.2 Ma, averaging 150.5 Ma, accompanied by a younger disturbance age of 144.3±1.7 Ma in the Lengshuigou intrusion, which is in excellent agreement with published sensitive high resolution ion micro-probe (SHRIMP) zircon date on the later monzodiorite porphyry phase in the Lenshuigou deposit. Two samples were selected for molybdenite ICP-MS Re-Os isotopic analyses from the Lengshuigou granodiorite porphyry, yielding Re-Os model ages from 149.2±2.7 Ma to 150.6±3.4 Ma, with a weighted mean age of 149.7±2.1 Ma. These mineralization ages overlap rock-forming ages of the host intrusions within the error range. This implies that the mineralization occurred in the Late Jurassic, which belongs to the tectonic phase B event of the Yanshan Movement, not Cretaceous as previously thought. Therefore, the Late Jurassic mineralization of the Zhashui-Shanyang district could be connected to the large-scale Yanshan molybdenum metallogenic period, the geodynamic regime of which is attributable to the far field response of convergence of surrounding plates, perhaps the approximately westward subduction of the Izanagi plate beneath the Eurasian continent. Copyright © 1999-2011 John Wiley & Sons, Inc. All Rights Reserved. Copyright © 1999-2011 John Wiley & Sons, Inc. All Rights Reserved. Source

Xie G.,Chinese Academy of Geological Sciences | Mao J.,Chinese Academy of Geological Sciences | Wang R.,Geological Exploration Institution | Ren T.,Northwest Mining and Geological Exploration Bureau for Nonferrous Metals | And 2 more authors.
Journal of Asian Earth Sciences

The newly discovered porphyry Cu deposits in the South Qinling Belt (SQB) have not been well researched as compared with the large porphyry Mo province in the southern North China Block (S-NCB), and the origin of granitoids associated with porphyry Cu mineralization in the Zha-Shan district, SQB is poorly constrained. Here, we present detailed zircon U-Pb geochronological, whole rock elemental and Sr-Nd isotopic data for important Late Mesozoic granitoid stocks associated with porphyry Cu deposits in the Zha-Shan district; these data are used to constrain the age and the source of magmas that formed these granitoids, and implication of regional metallogeny. The new zircon LA-ICPMS U-Pb ages presented here indicate that the granitoids related to porphyry Cu system at Chigou, Beishagou, Shuangyuangou and Yuanjiagou developed at 148-144Ma, 144Ma, 145-144Ma and 146Ma, respectively. These rocks are high-K calc-alkaline I-type granitoids, which are enriched in large ion lithophile elements (e.g., Th, U, and Pb) and light rare earth elements, are depleted in Nb, Ta and Ti, characterizing by wide variations in initial εNd(t) (-3.8 to -9.5), and moderate radiogenic Sr isotopes ((87Sr/86Sr)i=0.7046 to 0.7093). These features indicate that the magmas that formed the granitoids related to porphyry Cu system in the Zha-Shan district formed as a result of variable degrees of mixing between crustal and metasomatic lithospheric mantle. The new zircon LA-ICPMS U-Pb ages in this study, combined with previous published data, suggest that regional-scale Late Jurassic to Early Cretaceous granitoid stocks, and associated porphyry Cu and Mo systems in both the S-NCB and SQB formed almost contemporaneously, with 147-139Ma porphyry Mo deposits in the S-NCB and 148-145Ma porphyry Cu deposits in the SQB. The Cu-related intrusions contained a greater contribution of lithospheric mantle component than the Mo-related intrusions in the East Qinling Orogeny. © 2014 Elsevier Ltd. Source

Chen L.-H.,Aluminum Coperation of China | Wang R.-T.,Northwest Mining and Geological Exploration Bureau for Nonferrous Metals | Liu W.-D.,Aluminum Coperation of China
Northwestern Geology

Weibei bauxite belt is one of the two biggest bauxite belts in Shaanxi province. These deposits lying on the top of unconformity surface of Lower Paleozoic carbonate rocks are karst type bauxite deposits. Strictly controlled by basal ancient karst landform, the ore bodies generally show a stratiformlike, lenticular, and funnel-shaped pattern. The ore type is diasporic bauxite, mainly showing the clast, oolith, mud textures, and having a compact mass and stratiform structure. The main chemical compositions include Al 2O 3, SiO 2, Fe 2O 3 and TiO 2, with the average content of Al 2O 3 being 55.05%64.97%, SiO 2 12.44%-15.16%, and a A/S ratio of 3. 63-5. 22. The ore bodies are mainly controlled by hiatus, paleoclimate, paleolatitude, ancient landform, and so forth. Compared with the bauxite deposits in Henan and Shanxi provinces in which the bauxite ore bodies are mainly deposited, Weibei area has similar metallogenic geology and climate conditions, so it has a great prospecting perspective in Weibei area for exploring bauxite deposits, although the grade is somewhat low. Source

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