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Zhao S.,Wuhan University | Fu L.,Wuhan University | Wei J.,Wuhan University | Tan J.,Wuhan University | And 3 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2015

Zircon U-Pb age, major and trace elements and Sr, Nd isotope compositions of the Riariqu quartz diorites from the south of the Ganzi-Litang suture zone, northeastern Qiangtang terrane are studied to decipher its petrogenesis and geodynamic significance. LA-ICP-MS zircon U-Pb dating yields an emplacement age of 218±1 Ma for the intrusion. Bulk-rock analyses show that these rocks belong to the calc-alkaline series, with SiO2 contents ranging from 53.02% to 62.06%. They are enriched in Al2O3 (15.84%-17.00%) and CaO (6.71%-8.94%), depleted in TiO2 (0.49%-1.01%) and P2O5 (0.04%-0.12%), defining their metaluminous characteristics. All samples have high concentrations of MgO (3.31%-5.66%), Cr (33.45×10-6-176.64×10-6) and Ni (13.34×10-6-43.62×10-6), and resultant high Mg# (50-62). These rocks are enriched in LREE and LILE, and depleted in HFSE with low REE contents (38.05×10-6-61.58×10-6). The (87Sr/86Sr)i ratios range from 0.706 8 to 0.707 9, and εNd(t) values vary from -5.5 to -1.6. The geochemical and Sr-Nd isotopic compositions of the Riariqu quartz diorites are similar to those of high-Mg dioritoids/sanukitoids. We contend that the Riariqu quartz diorites were derived from low-degree partial melting (10%-15%) of a phlogopite-bearing spinel lherzolite mantle, which was metasomatized by sediment-derived melts. Fractional crystallization of pyroxene and amphibole might also occur during the magma evolution. The geochemical characteristics indicate that the Riariqu quartz diorites are arc-related magmatic rocks, and were generated in a subduction-related tectonic setting. Combined with the ophiolites and continental marginal arc lavas in the study area, and the regional adakites in the Yidun terrane, it is suggested that the Riariqu quartz diorites might be generated during the southwestward subduction of Ganzi-Litang Paleo-Tethys Ocean in the Late Triassic. ©, 2015, China University of Geosciences. All right reserved. Source

Li S.-P.,Qinghai Institute of Geology and Mineral Resources | Li S.-P.,Qinghai Institute of Geological Survey | Huang Q.-H.,Qinghai Institute of Geological Survey | Li X.-X.,Third Institute of Mineral Exploration in Qinghai | And 3 more authors.
Northwestern Geology | Year: 2013

Mohailaheng lead-zinc deposit is located in Jieduo back-arc foreland basin of the north rim of the north of Sanjiang metallogenic belt, its main ore-bearing horizon is the lower carboniferous supported heteropoly group of carbonate group, Containing ore formation and NWW fracture are important ore-controlling factors. Ore minerals are mainly galena, sphalerite, limonite and so on. The research results of lead isotope in the study area show that lead quarries μ is 9. 27-9. 77, the average of μ is less than 9.58, the average of ω is 39.99, lead isotopic composition has the characteristics of normal lead evolution. Lead quarries 206Pb/204 Pb is 18. 51-18. 92, the average of 208Pb/204 Pb is 38. 64, with the characteristics of stable isotopic composition. Lead mineralizing materials have the characteristics of crust-mantle evolution in Zartman lead isotope structure. Based on the above analysis, Mohailaheng lead-zinc mine mainly occurs in thick-super thick layers of carbonate rocks, and the mineralization had no direct relation to magmatic activity, which reflected that the lead came from lead mine construction of the upper earth's crust, lead containing formation or subprime fracture intersection part are favorable metallogenic or prospecting positions. Source

Li S.-P.,Qinghai Institute of Geology and Mineral Resources | Li S.-P.,Qinghai Institute of Geological Survey | Ma H.-Z.,CAS Qinghai Institute of Salt Lakes | Chen Y.-S.,Qinghai Seismological Bureau | And 3 more authors.
Geological Bulletin of China | Year: 2010

Potassium and magnesium salt deposit mainly enriches in the lower gypsum rock salt segment of Tagong Formation in Vientiane basin, Laos. The deposit is mainly composed of salt rock, carnallite, potassium salt, carnallite bearing potassium and a small amount of spar etc, and it belongs to single-layer structure. Trace elements of potassium and magnesium salt deposit such as Br and Rb are directly related to chloride, and therefore work as sign of potassium deposit prospecting in the Vientiane basin. These elements can reflected the development process of the original concentration of salt solution in certain degree. Sr and B with stable geochemical nature concentrate in the brine solution with the increase of brine concentration, so they may be indicative for potassium layer. It is confirm that the Vientiane basin brine comes from the southern Khorat basin by the analysis of trace elements, and it's possible that there is also surface water from deep fracture brine supply. This conclusion can be quite helpful to enrich the ancient solid potassium salt mineralization theory and to guide the research of Lanping-Simao basin evaporite salt and other potash deposits prospecting. Source

Li S.-P.,Qinghai Institute of Geology and Mineral Resources | Li S.-P.,Qinghai Institute of Geological Survey | Xie Z.-Y.,Geology Eight Teams of Qinghai Nonferrous Geological Exploration Bureau | Li X.-X.,The Third Institute of Mineral Exploration in Qinghai | And 3 more authors.
Chinese Rare Earths | Year: 2013

Dafengshan celestine deposit is located in the northwestern Qaidam Basin, composed of four mining areas, named as I, II, III and IV. The ore-bearing strata is the Tertiary Pliocene calcareous shale formation of Shizigou group. The orebodies are mostly thin-bedded and lenticular occurring in carbonaceous calcareous shale. The main ore minerals are celestite and strontianite. Celestite and ore-bearing rocks are characteristed by the lower contents of ∑ REE, LREE/HREE = 5.11~7.48, with an average value of 6.58, exhibiting a light REE enrichment and a significant Eu positive anomaly. The weak cerium negative in the host rock suggests that the mineralizing materials mainly come from deep hot brine. In addition, rich beneficial element fluid in surrounding areas of Qaidam Basin migrated to appropriate locations through chemical, infiltration metasomatism and was mineralized. Source

Li S.-P.,Qinghai Institute of Geological Survey Laboratory with Geological processes | Li S.-P.,Qinghai Institute of Geology and Mineral Resources | Li Y.-X.,Institute of Mineral Exploration in Qinghai | Pan T.,Qinghai Institute of Geological Survey Laboratory with Geological processes | And 6 more authors.
Northwestern Geology | Year: 2012

Elashan magmatic belt, an intersection location for East Kunlun, West Qinling and South Qilian orogenic belt, has complex internal structure and is an important junction in western China and ore concentration area in Qinghai. Marine volcanic widely outcrops in Elashan area and the rock types are ainly amygdaloidal basaltic andesite, amygdaloidal andesite, andesitic volcanic breccia, andesitic crystal-vitric tuff debris, andesitic breccia tuff lava, dacite and rhyolite. Marine volcanic rocks occurs by the volcanic strata, or laminated and lenticular shapes in the Suolaqu sandstone, Xingfucun fine-turbidite and Hekashan coarse-turbidite of the Hongshuichuan Formation, which is the product of a marine environment eruption. Chemical composition of volcanic rocks similar with the average chemical composition of island arc calc-alkaline andesite, The average δEu value is 0. 75 indicating a weak negative anomalies, (La/Sm) N, (Gd/ Yb) N values of the average were 5. 09, 1. 76, and There are significantly fractionated between light and heavy rare earth elements and enrich in LREE. The trace elements such as Ba, Rb and Th are strongly enriched and Ti, Cr and other elements are depleted. The Th×Ta/Hf 2 value is between 0. 029 to 0. 162, shows volcanic arc character. From the above, volcanic rocks of the Hongchuichuan Formation produced in stretching after the collision environment. Source

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