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Sui L.,Changan University | Sui L.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | Yang Y.,Changan University | Yang Y.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2012

Based on the existing post-processing methods of LiDAR data, a "separated step-by-step" filtering method of point cloud is proposed. First, a "rough" filtering method is applied to the LiDAR point cloud and the "ground points hypothesis" and "non-ground points hypothesis" are gained. Then, a causal auto-regressive model (car model) is imported to do modeling of the ground surface and hypothesis test for the two classes of point clouds, and ground points and non-ground points are classified by the results of the hypothesis testing. Finaly, the reliable classification results are gained. Compared to the "least squares prediction method" and "mathematical morphology", the results of LiDAR point cloud filtering by the "separated step-by-step" processing method are more reliable. Source


Dang B.,Changan University | Dang B.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | Zhao H.,Changan University | Zhao H.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | And 5 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

Triassic Yanchang Formation Chang 10 oil layer is a new oil-bearing layer which was found in the middle-east of Odors basin in 2007. Taking it as an example, on the basis of field outcrop and core observation combined with the indoor sensitivity test, sensitivity test, casting slice physical data, X-ray diffraction, SEM, mercury injection data and so on, the characteristics of reservoir sensitivity and its microscope mechanism were studied. The results show that the studied area Chang10 Reservoir possesses the characteristics such as slight water sensitivity and velocity sensitivity strata, medium-low to low saline sensibility, low-medium to low alkali sensitivity and high-medium to high acid sensitivity. The sensitivity is related to the existence of sensitive minerals such as chlorite-film, laumontite and the complex pore texture formed by diagenesis. Source


Liu C.-J.,Changan University | Pei X.-Z.,Changan University | Pei X.-Z.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | Li Z.-C.,Changan University | And 8 more authors.
Geological Bulletin of China | Year: 2012

The Neoproterozoic granitic gneisses in Tianshui area are located in the Xinyang-Yuanlong ductile shear belt which is the boundary between the North Qinling orogenic belt and the North Qilian tectonic zone. Geochemistry, petrogenesis and tectonic setting of the granitic gneisses are discussed in this paper. The granitic gneisses are rich in SiO2 and Al2O3, with A/CNK being 1.104~1.389, showing the supersaturation of Al and Si and suggesting the features of typical strongly peraluminous S-type granite. The ΣREE range from 128.27×10-6 to 242.09×10-6. Chondrite-normalized REE patterns show a rightward inclination with medium negative Eu anomalies. The trace element geochemistry is characterized by positive anomalies of Cs, Rb, Ba, Th, U, K, La, strongly-depleted negative anomalies of Nb, Ta, Ti, Hf, and evident negative anomalies of Ba, P, Sr. The granitic gneisses have features of crust-derived and typical continent-continent syn-collisional granites. The Paleoproterozoic Qinling Group whose protoliths were immature psammites containing higher pelitic compositions probably served as the source rocks. The generation of granitic gneisses resulted from dehydration melting due to the breakdown of micaceous minerals, with the possible existence of some fractional crystallization. The granitic gneisses suggest a collision between the North Qinling micro-block and its adjacent block in the Early Neoproterozoic period. It is a response of the assembly of Rodinia in West Qinling. Source


Xu T.,Changan University | Pei X.-Z.,Changan University | Pei X.-Z.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | Li R.-B.,Changan University | And 9 more authors.
Geology in China | Year: 2013

Zhangyangou bimodal volcanic rocks are located in Hengxianhe area, Sanchazi Lueyang segment of Mian -Lue tectonic zone. The bimodal volcanic rocks consist of metamorphosed basic volcanic rocks and metamorphosed acid-intermediate rocks in close association, and the protoliths are sub-alkaline basalt and sub alkaline rhyolitic dacite. On account of the higher REE concentrations in basalt than in rhyolitic-dacite, the authors hold that the origin of rhyoliticdacite was partial melting of the crustal material rather than the fractional crystallization of the basaltic magma. Basic volcanic rocks show the intraplate geochemical characteristics such as high Zr concentrations and Zr/Y ratios, and their marks of arc result from the hybridism of the crustal material. The result of U-Pb isotope dating by means of Laser Ablation Inductively Coupled Plasma Mass Spectrometry makes it clear that the formation age of the rhyolite is (728±10) Ma n=4 MSWD=0.14). Combined with the regional geological background, the authors consider that Zhangyangou bimodal volcanic rocks were formed in a continental rift environment under the crust extensional mechanism. The formation of Zhangyangou bimodal volcanic rocks heralded the opening of Neoproterozoic Ocean. This new achievement is of important significance both for the further study of the evolution of Mian Lue tectonic zone and the breakup of Rodinia sunercontinent and other continents on the north margin of the Yangtze block. Source


Wang Y.-C.,Changan University | Wang Y.-C.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | Pei X.-Z.,Changan University | Pei X.-Z.,Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education | And 15 more authors.
Geological Bulletin of China | Year: 2012

The newly identified Mesoproterozoic granitic gneisses are located in Paleoproterozic Longshan Group at the eastern end of Qilian Orogenic belt. In order to accurately determine the formation age of granitic gneisses from Changningyi, the authors carried out single grain zircon micro area U-Pb isotope dating by means of Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The Th/U ratios of zircons from granitic gneisses are between 0.50 and 2.09, and CL images show that the internal zircon has developed typical oscillatory girdle structure of magma growth, which belongs to the product of magma crystallization. And the original rock crystallization age of granitic gneiss is 1765Ma±57Ma, suggesting that granite rock was produced in early Mesoproterozoic period, and was probably formed in an post-orogenic environment, under which North China Block was experiencing the Lüliang movement. In addition, from the captured inherited magma zircon, the authors obtained the inherited ages of 1.95Ga and 2.20Ga. In combination with regional geological data and on the basis of a comprehensive study and analysis, the authors found that Qilian block remained a southwestern part of North China Block in Mesoproterozoic, for they had the same crystalline basement and structural properties. Besides, they both experienced the post orogenic stage and intracontinental stretch cracking stage after Lüliang movement. So they were probably closely related to the polymerization and cracking of Columbia supercontinent. Source

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