Yang Y.-Q.,Qinghai Geological Survey |
Li B.-L.,Jilin University |
Ma Y.-H.,No 5 Geological And Mineral Survey Institute Of Qinghai Province |
Zhu M.-X.,No 5 Geological And Mineral Survey Institute Of Qinghai Province
Northwestern Geology | Year: 2014
Aikenglesite Mo (Cu) deposit, a porphyry molybdenum (copper) deposit newly found in Eastern Kunlun in recent years, is located in the east of Kunnan compound splicing belt. The ore bodies are found in the granite porphyry as well as the outside broken monzonitic granite. The research of fluid inclusion in veined ore-bearing quartz and metallogenic characteristics show that the mineralization process can be divided into 4 stages: oxide stage (I), pyrite-pyrrhotite-quartz stage (II), molybdenite-polymetallic sulfide stage (III) and carbonatite stage (IV). The types of fluid inclusions mainly include gas-liquid two-phase inclusions and halite-bearing three-phase inclusions. The fluid belongs to H2O-NaCl system and the range of homogeneous temperature, salinity and density are 150-280°C, 2-30 wt% NaCl and 0.76-1.16g/cm3. The major metal sulfides are formed in low temperature (mainly concentrated on 200°C). After all, it is calculated that the metallogenic depth from middle to late mineralization stage is 1.2-3 km, and the orebodies are well preserved.
Qian Y.,Jilin University |
Sun F.,Jilin University |
Li B.,Jilin University |
Li S.,Qinghai Geological Survey |
Zhao J.,No 5 Geological And Mineral Survey Institute Of Qinghai Province
Acta Geologica Sinica | Year: 2014
In this paper we present new zircon U-Pb ages, whole-rock major and trace element analyses, and zircon Hf isotopic data for magmatic rocks in the Tuotuohe region of the western segment of the Jinshajiang suture. Our aim is to constrain the Early Permian-Late Triassic tectonic evolution of the region. Zircons from the magmatic rocks of the Tuotuohe region are euhedral-subhedral in shape and display fine-scale oscillatory zoning as well as high Th/U ratios (0.4-4.6), indicating a magmatic origin. The zircon U-Pb ages obtained using LA-ICP-MS are 281 ± 1 Ma, 258 ± 1 Ma, 244 ± 1 Ma, and 216 ± 1 Ma, which indicate magmatism in the Early Permian-Late Triassic. A diorite from Bashihubei (BSHN) has SiO2= 57.18-59.97 wt%, Al 2O3= 15.70-16.53 wt%, and total alkalis (Na2O + K2O) = 4.46-6.34 wt%, typical of calc-alkaline and metaluminous series. A gabbro from Bashibadaoban (BSBDB) belongs to the alkaline series, and is poor in SiO2 (45.46-54.03 wt%) but rich in Al2O 3 (16.19-17.39 wt%) and total alkalis (Na2O + K 2O = 5.48-6.26 wt%). The BSHN diorite and the BSBDB gabbro both display an enrichment of LREEs and LILEs and depletion of HFSEs, and they have no obvious Eu anomaly; they have relatively low MgO contents (2.54-4.93 wt%), Mg# values of 43 to 52, and low Cr and Ni contents (8.07-33.6 ppm and 4.41-14.2 ppm, respectively), indicating they differentiated from primitive mantle magmas. They have low Nb/U, Ta/ U, and Ce/Pb ratios (1.3-9.6, 0.2-0.8, and 0.1-18.1, respectively), and their initial Hf isotopic ratios range from +9.6 to +16.9 (BSHN diorite) and +6.5 to +12.6 (BSBDB gabbro), suggesting their primary magmas were derived mainly from the partial melting of a mantle wedge that had been metasomatized by subduction fluids. Taking all the new data together, we conclude that the western and eastern segment of the Jinshajiang suture regions underwent identical processes of evolution in the Early Permian-Late Triassic: oceanic crust subduction before the Early Permian, continental collision during the Early-Middle Triassic, and post-collisional extension from the Late Triassic. © 2014 Geological Society of China.
Wu S.-K.,Chang'an University |
Wu S.-K.,No 5 Geological And Mineral Survey Institute Of Qinghai Province |
Pei X.-Z.,Chang'an University |
Li Z.-C.,Chang'an University |
And 7 more authors.
Geological Bulletin of China | Year: 2012
With clastic rocks of Late Devonian Dacaotan Group on the north margin of West Qinling orogenic belt in eastern Gansu as the study object, the authors used LA-ICP-MS zircon U-Pb isotope geochronologic method to explore the material source of Da caotan Group. The results show that the age spectra of Dacaotan Group detrital zircon can be evidently divided into four groups: 422-518Ma, 756-887Ma, 1100-1231Ma and 2417-2736Ma, of which, the 422-486Ma age data possess the largest proportion, accounting for about 67% of the total data, having relatively concentrated ages, and showing a strong peak. The other ages possess a smaller proportion. The group of 422-518Ma indicates that its material sources were mainly from northern margin of western Qinling orogenic belt and Qilian orogenic belt in adjacent regions. The compositional ages suggest a sedimentary response to the orogenic erosion of a series of igneous rocks caused by the northward subduction and collision of mid-southern Qilian and western-Qinling micro-blocks in the Caledonian period. Detrital zircon U-Pb isotopic age group of 756-887Ma suggests that the material sources might have mainly come from the Qilian orogenic belt and northern margin of western Qinling orogenic belt. The age group of 1100-1231Ma implies that the material sources might have come from Qilian orogenic belt, and 2417-2736Ma age group indicates that the material sources were probably derived from the basement of north Qilian orogenic belt and northern margin of western Qinling orogenic belt, with part of the material sources probably derived from the North China plate basement. A comprehensive analysis shows that the material sources of Dacaotan Group were much more complicated and characterized by obvious diversity, derived from the northern margin of western Qinling orogenic belt, Qilian orogenic belt and the basement of North China plate. The Qilian orogenic belt and the northern margin of western Qinling orogenic belt made significant source contribution to the sedimentation of Dacaotan Group, with the Qilian orogenic belt possessing the dominant role.