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Yan’an Beilu, China

Liu F.,Chinese Academy of Geological Sciences | Cao F.,Geophysical and Geochemical Party | Zhang Z.X.,Xinjiang Institute of Ecology and Geography | Li Q.,Chinese Academy of Geological Sciences
Acta Petrologica Sinica | Year: 2014

There are very strong granitic activities in the Keketuohai pegmatite field. The biotite monzogranite bearing megaporphyric crystal in this paper outcrops near the east of No. 3 pegmatite. Its feature in field is very similar to the Aral granite in north. The result of LA-MC-ICP-MS U-Pb dating for the granite indicates that Pb/U ages range from 399.6Ma to 409. OMa (from 19 spot analyses), and the weighted mean age is 405.4 ± 1.4Ma (MSDW = 0.98). As an Early-Devonian pluton, it formed during strongest magma intrusion in region, much earlier than the Aral granite and genetically no relationship with No. 3 pegmatite. Geochemically, the granite is relatively enriched in Si (SiO 2 = 70.69% ∼ 73.81 %), Al (A12 O3 = 14.00% ∼ 15.74%), high K (in general, K20/Na20≥1), relatively poor in Fe, Mg, Ti and P, and its A/CNK ratios range from 1.09 to 1.12, suggesting high K calc-alkaline and strong peraluminous granite. Trace elements in the granite show markedly negative anomalies for Sr, Ti, Ba, P, Nb, Ta and positive anomalies for Th, U, La, Zr, Hf. LREE is relatively markedly fractionated, showing weak enrichment, HREE is weakly fractionated, and Eu has a moderate negative anomaly. 87Sr/86 Sr ratios of samples range from 0.72259 to 0.72810 and Nd/Nd from 0.51235 to 0.51237, closing to that of terrigenous deposits. ISr range from 0.70155 to 0.70341, f Sm/Nd from - 0.32 to -0.26 and Sm/Nd from 0.222 to 0.240, implying a weak fractionated and homogeneous isotopic system for Sm/Nd. εNd (t) range from -3.07 to -2.16 and t2DM concentrates on 1.35Ga, meaning Mid-Proterozoic basement. Based on studying the granite for its major, trace and REE elements, isotopic composition, related ratios, and contrasting with synchronous granite in the region, we suggest that granite in the paper formed in an active continental margin arc setting related to the subduction of plate, where thickening of crust resulted in partial melting of Mid-Proterozoic basement in the margin of Altay micro-continent and the added mantle-derived composition. Finally, biotite monzogranite formed during the fractionation of melting magma and following arising.


Gao Y.,Xian Institute of Geology and Mineral Resources | Li W.,Xian Institute of Geology and Mineral Resources | Qian B.,Xian Institute of Geology and Mineral Resources | Li K.,Xian Institute of Geology and Mineral Resources | And 5 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2014

The Weibao Pb-Zn deposit is located in the western Qimantage, east Kunlun, Xinjiang Province. The stratiform ore bodies are controlled by the strata, and occur in the banded epidote diopsite skarn in middile-lower Langyashan Formation of Jixianian Period. Major Pb-Zn (Cu) ore belongs to epidote diopsite skarn type. The ore minerals consist of galena, sphalerite and chalcopyrite, and the gangue minerals are composed of diopsite, epidote, calsite, chlorite and garnet. The sphalerite is characterized by higher content of Fe (2.206%-2.679%), lower content of Ga, Ge, Cd and Zn/Cd (143-150), and the content of Ag in galena is lower (0.163%-0.210%), which indicates that the metallic minerals may be formed closely with magmatic fluid. There are two types of fluid inclusions, liquid-rich two-phase and gas-rich two-phase. The average homogenization temperatures of two types of inclusions are 268.2 and 273.1℃, respectively. The gas components of CO2, CH4, N2 and H2 in inclusions indicate the ore-forming fluid may be derived from magmatic fluid. In all, the initial ore-forming fluid belongs to immiscibility, characterized by middle-high temperature, high salinity and low density. The values of δ34S vary from 0.49‰ to 2.41‰, which indicates that sulfur in sulfides was mainly from the magma. The sulfides have 206Pb/204Pb values from 18.254 to 18.336, 207Pb/204Pb values from 15.556 to 15.664, 208Pb/204Pb values from 38.060 to 38.367, which suggests that ore-forming metals come from deep magmatic activity, with little crust mixing. In summary, the Weibao Pb-Zn deposit may be a layered skarn type deposit related to Indosinian magmatic activity.


Yuan X.-L.,Geophysical and Geochemical Party | Yuan X.-L.,Urumqi Jinwei Map character Information and Science and Technology Co. | Duan X.-L.,Geophysical and Geochemical Party | Duan X.-L.,Urumqi Jinwei Map character Information and Science and Technology Co. | And 2 more authors.
Wutan Huatan Jisuan Jishu | Year: 2013

In order to realize 3D visualize of the geophysical and geochemical data, we can make discrete data of geological survey to gridding data, then render the grid to screen with OpenGL. This paper describes how to use OpenGL to render and edit 3d scence, and introduces the methods of dealing with large gridding data.


Peng Z.-Q.,Geophysical and Geochemical Party | Peng Z.-Q.,Urumqi Jimwei Map character information and Science and technology Co. | Duan X.-L.,Geophysical and Geochemical Party | Duan X.-L.,Urumqi Jimwei Map character information and Science and technology Co. | Bi W.,Geophysical and Geochemical Party
Wutan Huatan Jisuan Jishu | Year: 2012

Widely used inversion for TEM at present is based on the "Smoke Rings" theory which was referred to as "Smoke Rings inversion". It was first proposed by M. N. Nabighian. According to M. N. Nabighian's theory, Jiang Bangyuan presents a simple and fast approximate inversion method. This thesis trys to complete a TEM inversion software based on Jiang Bangyuan's theory. This software is suitable to the preliminary interpretation on field exploration because of this simplified "Smoke Rings" theory of inversion with a simple calculation and do not need the initial models.


Yuan X.-L.,Geophysical and Geochemical Party | Yuan X.-L.,Urumqi Jimwei Map character information and Science and technology Co. | Duan X.-L.,Geophysical and Geochemical Party | Duan X.-L.,Urumqi Jimwei Map character information and Science and technology Co. | Bi W.,Geophysical and Geochemical Party
Wutan Huatan Jisuan Jishu | Year: 2012

In order to observe 3D graphics, we rotate the scene around X, Y or Z axis, however, it's hard to rotate to the precise position we want. There is a better way that we construct a sphere which contains all the objects in scene . The objects rotate with the rotation of the sphere, and we call this sphere as arcball. This paper introduces the theory of arcball and how to realize the rotation of 3D graphics of geophysics and geochemistry by using arcball.

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