Shaanxi Institute of Regional Survey
Shaanxi Institute of Regional Survey
Zhao S.-L.,Shaanxi Institute of Regional Survey
Geological Bulletin of China | Year: 2011
Aim-to confirm the basin-and-range structural framework evolvement and provenance system of Carboniferous to Permian in Badanjaran basin. Method-by analyzing the content and the combined characteristic of clastic heavy mineral in sections of different depression belts of Carboniferous to Permian. Results-most of the heavy minerals in Badanjaran basin didn't suffer long-distance transport and the heavy minarals combination are different in different secondary units of different periods. In Carboniferous, the combination forms are zircon+apatite in Hongshishan-Heiyingshan depression, zircon+rutile+apatite+tourmaline in Hongliudaquan depression, zircon + rutile+apatite+tourmaline+garnet in Xilinhaote depression with garnet's drastically increasing upwards and zircon + rutile + apatite+ tourmaline in Zhusileng delve. Whereas, in Permian, the combination forms are zincon+apatite+ garnet in Hongshishan-Heiyingshan, zircon+rutile+apatite+tourmaline+garnet in Hongliudaquan depression, zircon + garnet + tourmaline in Xilinhaote depression, zircon+rutile+apatite+tourmaline+garnet in Zhusileng delve. Basin heavily shrinked in Late Permain northwards and marine sedimentary heavy mineral combination is zircon + rutile+apatite + tourmaline. Conclusion-there are two provenance systems in Badanjaran basin, Alashan-Langshan ancient land and Mazongshan slitter palaeohigh.
Liao S.-L.,Wuhan University |
Wei X.-H.,Shaanxi Institute of Regional Survey
Northwestern Geology | Year: 2014
Located in Mianxian County and with a typical heap crystal structure, the Guandipin ophiolite is an important part of the Mian-lue ophiolite structure zone. In this study, rock geochemistry and LA-ICP-MS zircon U-Pb dating are applied to analyze the intrusive environment and period of the amphibolite. The result shows that the amphibolite belongs to Calc-alkaline series with typically high content of MgO and CaO but low K2O. The TiO2 content is similar to that of active continental margin and island arc volcanic rocks. Besides, it is rich in LILE such as Ba, Th, U and LREE, while low in HFSE of Nb and Ta. Moreover, the fractionation of light and heavy REE is not obvious. These features indicate that it is probably the product of the northward subduction of the Mian-lüe oceanic basin under island arc environment. Its geochemistry characteristics are similar to the Indosinian granites, suggesting that they may derive from the same source, and are contaminated by the continental crust. LA-ICP-MS zircon U-Pb dating result shows that the diagenetic age of the amphibolite is 222. 5±2. 1 Ma, which indicates that it was formed in the Late Triassic Epoch. This age is a bit earlier than the granites in the study area, implying that the ancient Mian-lüe was formed in the Late Triassic Epoch. This age is a bit earlier than the granites in the study area, implying that the ancient Mian-liie oceanic crust continued northward subduction until the forming of island arc volcanic rocks in Late Triassic or later, and then entered the collision orogenic stage.
Xing X.-L.,Shaanxi Institute of Regional Survey |
Wang J.-W.,Shaanxi Institute of Regional Survey |
Hu Y.-J.,Shaanxi Institute of Regional Survey
Northwestern Geology | Year: 2013
The output and distribution of ore bodies in Zhaodagou ore section are strictly controlled by the NWW-direction F1∼F5 compressive-shear fault. The tensile fracture formed in early ore-forming stage is the main accumulating space of ore body. Regardless of the ore body or tensile fracture, both of them in deep area show the intermittent extension along the Fl amp;sim; F5 fracture, reflecting that there is extension in the deep area of ore section that F1∼F5 fracture passes through. Therefore, the structural ore-control sign of Zhaodagou ore section is clear, and it is predicated that it has the similar ore - accumulating rules and prospecting sign in ground surface and deep area with the neighboring western area of Zhaodagou and Jindonggou area, which can be regarded as the main prospective area to look for ore body.