The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related ...The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits： Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns.展开更多
以四川省旺苍县水磨—大河地区为研究区,利用美国ASD Field Spec 3便携式地物光谱仪野外实测岩矿波谱数据和ASTER遥感影像数据,基于GIS平台,根据野外实测的岩石光谱曲线和USGS光谱库的典型岩石光谱曲线提取端元波谱,对区域影像像元的光...以四川省旺苍县水磨—大河地区为研究区,利用美国ASD Field Spec 3便携式地物光谱仪野外实测岩矿波谱数据和ASTER遥感影像数据,基于GIS平台,根据野外实测的岩石光谱曲线和USGS光谱库的典型岩石光谱曲线提取端元波谱,对区域影像像元的光谱曲线进行匹配,采用ENVI4.4软件自动信息提取与人机交互解译相结合的方式,进行岩性分类,可以有效地划分区内岩性界线,满足填图需求,对辅助该区区域基础地质调查、矿产普查等具有重要的应用价值。展开更多
Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran a...Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran and is mostly covered by volcanic rocks, which are intruded by porphyritic subvolcanic intrusions in some places. Application of the spectral angle mapper （SAM） technique to Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） images detected sericitic, argillic, and propylitic alterations, silicification, and secondary iron oxides. The alteration is linear and associated within vein-type mineralization. Twelve prospective areas are selected for detailed exploration and based on our processing results, in addition to NW-SE faults, which are associated with Cu mineralization indications, NE-SW faults are also shown to be important. Based on the presence of subvolcanic rocks and numerous Cu ± Pb-Zn vein-type mineralizations, extensive alteration, high anomaly of Cu and Zn （up to 100 ppm）, the age （43.6 to 31.4 Ma） and the initial $78r/S6Sr ratio （0.7047 to 0.7065） of the igneous rocks, and the metallogenic epoch of the Lut block （middle Eocene-lower Oligocene） for the formation of porphyry Cu and epithermal deposits, the studied area shows great potential for porphyry copper deposits.展开更多
基金supported by National Geoscience Database and Geological Survey of Iran
文摘The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits： Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns.
文摘以四川省旺苍县水磨—大河地区为研究区,利用美国ASD Field Spec 3便携式地物光谱仪野外实测岩矿波谱数据和ASTER遥感影像数据,基于GIS平台,根据野外实测的岩石光谱曲线和USGS光谱库的典型岩石光谱曲线提取端元波谱,对区域影像像元的光谱曲线进行匹配,采用ENVI4.4软件自动信息提取与人机交互解译相结合的方式,进行岩性分类,可以有效地划分区内岩性界线,满足填图需求,对辅助该区区域基础地质调查、矿产普查等具有重要的应用价值。
文摘Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran and is mostly covered by volcanic rocks, which are intruded by porphyritic subvolcanic intrusions in some places. Application of the spectral angle mapper （SAM） technique to Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） images detected sericitic, argillic, and propylitic alterations, silicification, and secondary iron oxides. The alteration is linear and associated within vein-type mineralization. Twelve prospective areas are selected for detailed exploration and based on our processing results, in addition to NW-SE faults, which are associated with Cu mineralization indications, NE-SW faults are also shown to be important. Based on the presence of subvolcanic rocks and numerous Cu ± Pb-Zn vein-type mineralizations, extensive alteration, high anomaly of Cu and Zn （up to 100 ppm）, the age （43.6 to 31.4 Ma） and the initial $78r/S6Sr ratio （0.7047 to 0.7065） of the igneous rocks, and the metallogenic epoch of the Lut block （middle Eocene-lower Oligocene） for the formation of porphyry Cu and epithermal deposits, the studied area shows great potential for porphyry copper deposits.
