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Hao N.,China University of Geosciences | Yuan W.,China University of Geosciences | Zhang A.,Qinghai No 3 Geology And Prospecting Institution | Feng Y.,China University of Geosciences | And 4 more authors.
Journal of Earth System Science | Year: 2015

The East Kunlun Orogenic Belt has undergone a composite orogenic process consisting of multiple orogenic cycles and involving many types of magmatic rocks spread over the whole district. However, due to bad natural geographical conditions and complex superimposed orogenic processes, most of the Caledonian orogenic traces were modified by the late tectonic uplift and denudation, so these rocks are poorly studied. Multiperiodic magmatic activity during the Late Silurian (approximately 420 Ma)-Late Devonian (approximately 380 Ma) exists in the Qimantagh area. We obtained 5 zircon U-Pb ages from the Late Silurian-Late Devonian granitoids in the Qimantagh area. Those ages are 420.6 ± 2.6 Ma (Nalingguole biotite monzogranite), 421.2 ± 1.9 Ma (Wulanwuzhuer potassium granite), 403.7 ± 2.9 Ma (Yemaquan granodiorite), 391.3 ± 3.2 Ma (Qunli granite porphyry), and 380.52 ± 0.92 Ma (Kayakedengtage granodiorite). These granitoids belong to the sub-alkaline, high-K calc-alkaline, metaluminous or weakly or strongly peraluminous series. The rocks are right oblique types, having overall relative LREE enrichment and HREE depletion, though rocks from different times may exhibit different degrees of Eu anomalies or overall moderate Eu depletion. The rocks are rich in large ion lithophile elements (LILE), such as Rb, Th, and K, and high field strength elements (HFSE), such as Zr and Hf, and are depleted in Ba, Nb, Ta, Sr, P, Eu, and Ti. The rocks have complex composition sources. The Late Silurian granitoids are mainly crust-derived. Most of the Devonian granitoids are crust-mantle mixed-source and only some parts of them are crust-derived, especially the Middle Devonian granitoids. Those mid-acidic and acidic intrusive rocks are formed in a post-collision tectonic setting, lithosphere delamination may have occurred in the Early Devonian (407 Ma), and the study area subsequently experienced an underplating of the mantle-derived magma at least until the Late Devonian (380 Ma). © Indian Academy of Sciences. Source

Zhang W.-Q.,Qinghai No 3 Geology And Prospecting Institution | Cai B.-Y.,Qinghai No 3 Geology And Prospecting Institution | Bai G.-L.,Qinghai No 3 Geology And Prospecting Institution | Meng J.-H.,Qinghai No 3 Geology And Prospecting Institution | Luan A.-H.,Qinghai Coal Geological Exploration Institute
Northwestern Geology | Year: 2010

It is hard to achieve favorable prospecting effect by using IP technology of grounding mode in the working areas with the surface covered by gravels or areas with worse grounding conditions. However , Transient Electromagnetics Method of using phrase to phrase loops has advantages that can not be replaced by other methods as no grounding need, high diastropic resolution, and the parameter that can make use of is more, being applicable to various geography environment work, and be subjected to the topographic influence smaller, and favorable effect of mineral prospecting. Rational setting of the emission current is particularly supposed to be noticed, otherwise to be different exploration results. Powerful emission current does not necessarily help to find the abnormality caused by low resistive anomaly and improve abnormal curve amplitude accordingly, which will impact on the final exploration. The importance of setting emission current properly is exemplified by the mineral areas in Dongmozhazhua and Narigongma. Source

Fan C.-A.,Qinghai No 3 Geology And Prospecting Institution | Yan Y.-B.,Qinghai No 3 Geology And Prospecting Institution | Wang Y.-Q.,Qinghai No 3 Geology And Prospecting Institution
Wutan Huatan Jisuan Jishu | Year: 2013

The selection of geophysical methods is very important when geological exploration work is carried out in the areas of traveling dunes. The high precision magnetic surveying is the preferred geophysical technique to find the iron metallic ore. It played a very important role in geological prospecting work in Qimantage area. Tawenchahan area in the middle of the Qimantage metallogenic belt is a favorable area to find skarn type iron metallic ore. Large-scale ground high precision magnetic surveying and drilling is an effective combination in this area. Due to a large area of traveling dunes are distributed in the region with few meters to dozens of meters high and the strata are covered by desert, so the surface geological work is difficult to play a role. Inferred interpretation of the large precision magnetic anomaly is critical in this composition of the exploration method. This article is to illustrate the prospecting effect of 1:10 000 precision magnetic survey in desert areas by examples. Source

Zhna W.-Q.,Qinghai No 3 Geology And Prospecting Institution | Zhang A.-K.,Qinghai No 3 Geology And Prospecting Institution | Meng J.-H.,Qinghai No 3 Geology And Prospecting Institution | Guo K.-M.,Qinghai No 3 Geology And Prospecting Institution | Ma J.-Z.,Qinghai No 3 Geology And Prospecting Institution
Northwestern Geology | Year: 2012

It is very important that choosing the methods of exploration when we carry out geological work in areas whose surface is covered seriously. High-precision magnetic method is the preferred method of geophysical techniques for finding magnetic mineral, and this method played a very important role in geological prospecting work in Qimantage area. There are a large area of sand beams in the west of Nalingguole river, which are a few meters to ten meters in height. According to the data of bore hole, the overburden thickness is 160- 314m. Trail are all covered by desert, and the ground magnetic anomaly is wide-gentle and unobvious. Lack of local geological data led to the interpretation of magnetic survey data is very difficult, and can not provide the exact location to verify bore hole. So the progress of magnetic anomaly interpretation plays a key role. This paper will illustrate examples of using the technology of joint inversion of surface and borehole magnetic data, in order to get more breakthrough in the desert coverage prospecting. Source

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