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Extraction of Mineral Alteration Zone from ETM+ Data in Northwestern Yunnan,China
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作者 赵志芳 张玉君 +1 位作者 成秋明 陈建平 《Journal of China University of Geosciences》 SCIE CSCD 2008年第4期416-420,共5页
Alteration is regarded as significant information for mineral exploration. In this study, ETM+ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan (云南), China. The ... Alteration is regarded as significant information for mineral exploration. In this study, ETM+ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan (云南), China. The principal component analysis (PCA) of ETM+ bands 1, 4, 5, and 7 was employed for OH alteration extractions. The PCA of ETM+ bands 1, 3, 4, and 5 was used for extracting Fe^2+ (Fe^3+) alterations. Interfering factors, such as vegetation, snow, and shadows, were masked. Alteration components were defined in the principal components (PCs) by the contributions of their diagnostic spectral bands. The zones of alteration identified from remote sensing were analyzed in detail along with geological surveys and field verification. The results show that the OH^- alteration is a main indicator of K-feldspar, phyllic, and prophilized alterations. These alterations are closely related to porphyry copper deposits. The Fe^2+ (Fe^3+) alteration indicates pyritization, which is mainly related to hydrothermal or skarn type polymetallic deposits. 展开更多
关键词 mineral alteration extraction from ETM+ data PCA OH^- alteration Fe^2+ (Fe^3+) alteration northwestern Yunnan China
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Geochronology, Geochemistry and Tectonic Significance of the Early Carboniferous Gabbro and Diorite Plutons in West Ujimqin, Inner Mongolia 被引量:13
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作者 Shiwei Ma Changfeng Liu +3 位作者 Zhiqin Xu Zhiguang Zhou Jinyuan Dong Hongying Li 《Journal of Earth Science》 SCIE CAS CSCD 2017年第2期249-264,共16页
Early Carboniferous gabbros and diorites are distributed in West Ujimqin, Inner Mongolia. The LA-ICP-MS zircon U-Pb ages of the gabbro and diorite samples are 321± 2 Ma(MSWD=0.65) and 319.4± 1.5 Ma(MSWD=0... Early Carboniferous gabbros and diorites are distributed in West Ujimqin, Inner Mongolia. The LA-ICP-MS zircon U-Pb ages of the gabbro and diorite samples are 321± 2 Ma(MSWD=0.65) and 319.4± 1.5 Ma(MSWD=0.42), respectively. In addition, new geochemistry data from three gabbro and three diorite samples are presented. All six samples show high Al_2O_3 contents but low-TiO_2 contents, belonging to tholeiitic and calc-alkali basalt series. All of the samples have similar chondrite normalized REE patterns characterized by moderate depletion in LREE similar to normal middle oceanic ridge basalt(MORB). The MORB and PM-normalized trace element patterns show the enrichment in large ion lithophile elements(LILE, e.g., Rb, Ba and Sr), depletion in high field strength elements(HFSE) and distinctly negative Nb and Ta anomalies similar to volcanic arc basalt. Furthermore, as shown in the correlation plots of La/Ba vs. La/Nb, Ba/La vs. Ce/Pb, Th/La vs. Ce/Pb, Nb/La vs. Ba/Rb, and Nb/Y vs. La/Yb, the magma source has underwent contamination and metasomatism from the subduction fluid. According to the Zr/Nb, La/Nb, and La/Ta ratios and the Nb/Y vs. Zr/Y and Sm/Yb vs. La/Sm diagrams, the magma was derived from shallow depleted lithospheric mantle and formed by moderate(5%~20%) partial melting of spinel lherzolites. Tectonic setting discrimination diagrams reveal that the gabbros and diorites display both characteristics of MORB and volcanic arc basalt, which is consistent with their geochemical characteristics. On the basis of the geochemical features of these samples, combined with regional geological data and many previous researches in the study area, the Early Carboniferous gabbros and diorites of West Ujimqin are suggested to be formed in an intensely extensional rift setting, and a limited immature ocean basin probably formed after subsequent development. 展开更多
关键词 zircon U-Pb age geochemistry extensional setting Early Carboniferous West Ujimqin
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Detrital zircon dating and tracing the provenance of dinosaur bone beds from the Late Cretaceous Wangshi Group in Zhucheng, Shandong, East China 被引量:4
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作者 Wei An Hong-Wei Kuang +7 位作者 Yong-Qing Liu Nan Peng Ke-Min Xu Huan Xu Peng Zhang Ke-Bai Wang Shu-Qing Chen Yan-Xia Zhang 《Journal of Palaeogeography》 SCIE CSCD 2016年第1期72-99,共28页
The mass burial of dinosaur bone fossils in the Late Cretaceous Wangshi Group in Zhu- cheng, Shandong Province has been a research focus in recent years. However, the prov- enance of the dinosaur bone fossils and the ... The mass burial of dinosaur bone fossils in the Late Cretaceous Wangshi Group in Zhu- cheng, Shandong Province has been a research focus in recent years. However, the prov- enance of the dinosaur bone fossils and the accurate depositional age of the bone beds remain ambiguous. Through U-Pb dating of detrital zircons collected from six conglom- erate samples from the dinosaur bone beds, we found that the youngest single grain age (YSG) of sample 090414-24-D was 77.3 Ma, representing the maximum depositional age of the dinosaur fossil beds and sediments. This also indicates that the Hongtuya Formation was deposited during the Campanian. Dating results revealed an age peak of 120 110 Ma, which corresponds with the peak age of volcanic rocks of the Lower Cretaceous Qingshan Group. The volcanic rocks of the Qingshan Group are mainly exposed in Laiyang, to the north of Zhucheng, although a few also appear to the south and northwest. Through analysis of conglomerate composition and palaeocurrents in the sediments containing the bone beds, we found that the three different data sets of gravel compositions of the con- glomerates were mainly composed of volcanic or pyroclastic rocks. Three different data sets of palaeocurrents suggested that the main sediment source of the Wangshi Group dinosaur bone beds was from the north-northwest of the Basin. Only one data set had a provenance south of the basin. This study revealed that the areas of Laiyang and the Yishu Fault Zone were the main provenance areas of both the dinosaur bone fossils and the sediments of the Wangshi Group in Zhucheng. The southern margin of the Zhucheng Basin may be a secondary source area. This research provides an important basis for judging the deposition time and the sediment source of fossil layers in the Wangshi Group, as well as reconstructing the palaeogeography of the Wangshi Group in the liaolai Basin. 展开更多
关键词 Dinosaur bone beds Provenance Detrital zircon Geochronology Wangshi GroupShandong Zhucheng
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