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
Based on comprehensive petrological, geochronological, and geochemical studies, this study analyzed the relationships between the Beiya gold-polymetallic skarn deposit and quartz syenite porphyries, and discussed the ...Based on comprehensive petrological, geochronological, and geochemical studies, this study analyzed the relationships between the Beiya gold-polymetallic skarn deposit and quartz syenite porphyries, and discussed the source（s） and evolution of magmas. Our results suggest that syenite porphyries（i.e. the Wandongshan, the Dashadi, and the Hongnitang porphyries）, which formed between the Eocene and the early Oligocene epochs, are the sources for the gold-polymetallic ores at the Beiya deposit. Carbonate rocks（T2 b） of the Triassic Beiya Formation in the ore district provide favorable host space for deposit formation. Fold and fault structures collectively play an important role in ore formation. The contact zone between the porphyries and carbonates, the structurally fractured zone of carbonate and clastic rocks, and the zone with well-developed fractures are the ideal locations for ore bodies. Four types of mineralization have been recognized： 1） porphyry-style stockwork gold–iron（copper） ore, 2） skarn-style gold-iron（copper and lead） ore in the near contact zone, 3） strata-bound, lense-type lead–silver–gold ore in the outer contact zone, and 4） distal vein-type gold–lead–silver ore. Supergene processes led to the formation of oxide ore, such as the weathered and accumulated gold–iron ore, the strata-bound fracture oxide ore, and the structure-controlled vein-type ore. Most of these ore deposits are distributed along the axis of the depressed basin, with the hypogene ore controlling the shape and characteristics of the oxide ore. This study provides critical geology understanding for mineral prospecting scenarios.展开更多
Since the Cenozoic,especially the Quaternary,tectonic movement has been strengthening in northwestern Yunnan,China.The tectonic elevation rate of mountains changed from 0.3～ 1.7 mm/a(before the Holocene)to 2～ 7.1 mm...Since the Cenozoic,especially the Quaternary,tectonic movement has been strengthening in northwestern Yunnan,China.The tectonic elevation rate of mountains changed from 0.3～ 1.7 mm/a(before the Holocene)to 2～ 7.1 mm/a(after the Holocene).The subsiding velocity of the Holocene basins increases by 1～ 2 orders of magnitude relative to the Pleistocene.The displacement rate of the Quaternary fractures increases continuously.Modern crustal stress values become high.Tectonic deformation speeds up.Seismic activities strengthen.Geothermal flux anomaly is pronounced.The strengthening tectonic activities will result in changes of the topographic frame of northwestern Yunnan,worsen mountain geologic disaster,speed up the contraction of lakes and decrease the regional stability.Therefore,human beings will face the challenge of a more rigorous environment.展开更多
The paper discusses the features of active tectonics,seismicity and neotectonic environment in the Northwestern Yunnan extensional region.The intensity of both tectonic activity and seismicity is strong near the south...The paper discusses the features of active tectonics,seismicity and neotectonic environment in the Northwestern Yunnan extensional region.The intensity of both tectonic activity and seismicity is strong near the south and north boundaries in the areas,but weak in the middle.The distribution of the strongest subsided areas,lacustrine terrace and Quaternary fold is characterized by the diagonal symmetry.Formation of extensional tectonics in the Northwestern Yunnan can be explained by passive model,experiencing the action of compressional force in the N-S direction and shear force in the SW-NE direction,and classified as a special pull-apart tectonics.The direction of the composite force is NNE,which is coincided with the results acquired by the methods of water-compressed rupture and physical modelling.展开更多
Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge por...Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.展开更多
The regional geologic and geomorphic observations show that an active arcuate normal fault constitutes the main boundary fault of the Haba-Yulong Snow Mountains (HYSM). This fault is called eastern piedmont fault of H...The regional geologic and geomorphic observations show that an active arcuate normal fault constitutes the main boundary fault of the Haba-Yulong Snow Mountains (HYSM). This fault is called eastern piedmont fault of Haba-Yulong Snow Mountains (HYPF). The fault consists of two segments with differential trend; the northern segment is NW-trending and NE-dipping and the southern section is S-N trending and E-dipping. Three sets of fault scarps cutting late Quaternary landforms and their dating results indicate that the fault is a prominent Holocene active fault and its throw rates are 0.3―1.4 mm/a during late Quaternary. The geometry and kinematics of the fault suggest that the arcuate normal faulting or rifting are typical surface deformation pattern at the two tips of the Z-shaped rift zone of northwestern Yunnan, which is related to regional east-west extension accompanying clockwise rota- tion of micro-block.展开更多
北衙金多金属矿田是藏东-金沙江-哀牢山新生代富碱斑岩成矿带中南段的代表性矿床之一,发育一个与富碱斑岩密切相关的金多金属成矿系统。本文较为系统地分析了矿田内的成岩成矿作用特征及其演化过程,并探讨其与印-亚碰撞造山过程的响应...北衙金多金属矿田是藏东-金沙江-哀牢山新生代富碱斑岩成矿带中南段的代表性矿床之一,发育一个与富碱斑岩密切相关的金多金属成矿系统。本文较为系统地分析了矿田内的成岩成矿作用特征及其演化过程,并探讨其与印-亚碰撞造山过程的响应关系。富碱斑岩具有埃达克岩的地球化学亲合性,其源区是喜马拉雅期印-亚碰撞造山造成的软流圈向东挤出汇聚使大规模走滑断裂活化,诱发玄武质下地壳部分熔融的壳幔过渡层,成岩年龄可分为第一期(65～59Ma)、第二期(36～32Ma)、第三期(26～24Ma)和最晚期(3.8～3.6Ma)等4期,其中第二、三期与富碱岩带北段的两期岩浆集中活动时期基本吻合,形成的斑岩对金多金属成矿较为有利。区内金多金属矿床可划分为三个矿床类型和七个矿床亚类,即与喜马拉雅早—中期斑岩有关的金多金属矿床(Ⅰ),包括接触带夕卡岩型、斑岩型和热液充填型(及熔浆型)金多金属矿床;与喜马拉雅第三期斑岩有关的金多金属矿床(Ⅱ),包括爆破角砾岩型和叠加热液改造型金多金属矿床;以及与喜马拉雅期表生作用有关的风化堆积型金矿床(Ⅲ),包括古砂矿型和红色粘土型金矿床。Ⅰ、Ⅱ类型矿床受富碱斑岩及伴生的 NE 到 NNE 向断裂控制,赋存于富碱斑岩体内、内外接触带及其附近围岩的层间破碎带或构造裂隙带中,在成因和空间上与斑岩及隐爆角砾岩等密切有关。成矿物质和成矿流体主要来源于地幔,围岩地层只是提供了成矿的空间,不同类型的矿体之间呈"贯通式"的时间和空间关系,构成了一个统一的喜马拉雅期富碱斑岩-热液型金多金属成矿系统。先期形成矿床明显受后期岩浆热液的叠加改造,但矿化分布和成矿元素组合仍表现为以斑岩为中心,存在 CuAu(Mo)多金属→FeCuAuPbZn 多金属→AuPhZnAg 多金属的分带特征。从最早期含金铁矿床形成之后,原生金矿的次生富集和表生成矿作用就已开始,并形成不同成因类型的风化-堆积型金矿床。其中,古红色粘土型金矿床的成矿主要发生在始新世到渐新世,河-湖相古砂金矿床形成于23～5Ma 期间,红色粘土型(残坡积型)金矿床可从始新世一直延续至今。通过与区域斑岩成岩成矿演化时序的对比,提出与藏东-金沙江-哀牢山斑岩成矿带上的众多矿床一样,北衙矿田内的成岩成矿作也是喜马拉雅期印-亚陆陆碰撞造山带成岩成矿作用在东南缘构造转换带的远程效应,记录了印-亚大陆碰撞造山的详细过程。因而,该矿田深部及外围地区,仍存在巨大的找矿潜力。盐源-丽江断裂带可能也是一务与藏东-金沙江.哀牢山斑岩成矿带联系密切而又相对独立的富碱斑岩成矿带。展开更多
基金supported by the project "Remote Sensing Alteration Abnormity Extraction from Geological Survey in Northwestern Yunnan, China" from China Geological Survey
文摘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.
基金jointly financially supported by “Yunling Scholars” Research Project from Yunnan Province,China Geological Survey Project(No.DD20160124 and 12120114013501)the National Natural Science Foundation of China(grant No.41602103)the “Study on metallogenic regularities and metallogenic series of gold-polymetallic deposits,Northwestern Yunnan Province” research project(E1107)from Yunnan Gold&Mining Group Co.,Ltd
文摘Based on comprehensive petrological, geochronological, and geochemical studies, this study analyzed the relationships between the Beiya gold-polymetallic skarn deposit and quartz syenite porphyries, and discussed the source（s） and evolution of magmas. Our results suggest that syenite porphyries（i.e. the Wandongshan, the Dashadi, and the Hongnitang porphyries）, which formed between the Eocene and the early Oligocene epochs, are the sources for the gold-polymetallic ores at the Beiya deposit. Carbonate rocks（T2 b） of the Triassic Beiya Formation in the ore district provide favorable host space for deposit formation. Fold and fault structures collectively play an important role in ore formation. The contact zone between the porphyries and carbonates, the structurally fractured zone of carbonate and clastic rocks, and the zone with well-developed fractures are the ideal locations for ore bodies. Four types of mineralization have been recognized： 1） porphyry-style stockwork gold–iron（copper） ore, 2） skarn-style gold-iron（copper and lead） ore in the near contact zone, 3） strata-bound, lense-type lead–silver–gold ore in the outer contact zone, and 4） distal vein-type gold–lead–silver ore. Supergene processes led to the formation of oxide ore, such as the weathered and accumulated gold–iron ore, the strata-bound fracture oxide ore, and the structure-controlled vein-type ore. Most of these ore deposits are distributed along the axis of the depressed basin, with the hypogene ore controlling the shape and characteristics of the oxide ore. This study provides critical geology understanding for mineral prospecting scenarios.
基金The study is finicially supported by the Natural Science Foundation of Yunnan Province,China(No.97D031M).
文摘Since the Cenozoic,especially the Quaternary,tectonic movement has been strengthening in northwestern Yunnan,China.The tectonic elevation rate of mountains changed from 0.3～ 1.7 mm/a(before the Holocene)to 2～ 7.1 mm/a(after the Holocene).The subsiding velocity of the Holocene basins increases by 1～ 2 orders of magnitude relative to the Pleistocene.The displacement rate of the Quaternary fractures increases continuously.Modern crustal stress values become high.Tectonic deformation speeds up.Seismic activities strengthen.Geothermal flux anomaly is pronounced.The strengthening tectonic activities will result in changes of the topographic frame of northwestern Yunnan,worsen mountain geologic disaster,speed up the contraction of lakes and decrease the regional stability.Therefore,human beings will face the challenge of a more rigorous environment.
文摘The paper discusses the features of active tectonics,seismicity and neotectonic environment in the Northwestern Yunnan extensional region.The intensity of both tectonic activity and seismicity is strong near the south and north boundaries in the areas,but weak in the middle.The distribution of the strongest subsided areas,lacustrine terrace and Quaternary fold is characterized by the diagonal symmetry.Formation of extensional tectonics in the Northwestern Yunnan can be explained by passive model,experiencing the action of compressional force in the N-S direction and shear force in the SW-NE direction,and classified as a special pull-apart tectonics.The direction of the composite force is NNE,which is coincided with the results acquired by the methods of water-compressed rupture and physical modelling.
文摘Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.
基金Supported by Department of International Cooperation of Ministry of Science and Technology of China (Grant No. 2006DFA21320)China Geological Survey of Ministry of Land and Resources (Grant No. 1212010541404)National Natural Science Foundation of China (Grant No. 40501006)
文摘The regional geologic and geomorphic observations show that an active arcuate normal fault constitutes the main boundary fault of the Haba-Yulong Snow Mountains (HYSM). This fault is called eastern piedmont fault of Haba-Yulong Snow Mountains (HYPF). The fault consists of two segments with differential trend; the northern segment is NW-trending and NE-dipping and the southern section is S-N trending and E-dipping. Three sets of fault scarps cutting late Quaternary landforms and their dating results indicate that the fault is a prominent Holocene active fault and its throw rates are 0.3―1.4 mm/a during late Quaternary. The geometry and kinematics of the fault suggest that the arcuate normal faulting or rifting are typical surface deformation pattern at the two tips of the Z-shaped rift zone of northwestern Yunnan, which is related to regional east-west extension accompanying clockwise rota- tion of micro-block.
文摘北衙金多金属矿田是藏东-金沙江-哀牢山新生代富碱斑岩成矿带中南段的代表性矿床之一,发育一个与富碱斑岩密切相关的金多金属成矿系统。本文较为系统地分析了矿田内的成岩成矿作用特征及其演化过程,并探讨其与印-亚碰撞造山过程的响应关系。富碱斑岩具有埃达克岩的地球化学亲合性,其源区是喜马拉雅期印-亚碰撞造山造成的软流圈向东挤出汇聚使大规模走滑断裂活化,诱发玄武质下地壳部分熔融的壳幔过渡层,成岩年龄可分为第一期(65～59Ma)、第二期(36～32Ma)、第三期(26～24Ma)和最晚期(3.8～3.6Ma)等4期,其中第二、三期与富碱岩带北段的两期岩浆集中活动时期基本吻合,形成的斑岩对金多金属成矿较为有利。区内金多金属矿床可划分为三个矿床类型和七个矿床亚类,即与喜马拉雅早—中期斑岩有关的金多金属矿床(Ⅰ),包括接触带夕卡岩型、斑岩型和热液充填型(及熔浆型)金多金属矿床;与喜马拉雅第三期斑岩有关的金多金属矿床(Ⅱ),包括爆破角砾岩型和叠加热液改造型金多金属矿床;以及与喜马拉雅期表生作用有关的风化堆积型金矿床(Ⅲ),包括古砂矿型和红色粘土型金矿床。Ⅰ、Ⅱ类型矿床受富碱斑岩及伴生的 NE 到 NNE 向断裂控制,赋存于富碱斑岩体内、内外接触带及其附近围岩的层间破碎带或构造裂隙带中,在成因和空间上与斑岩及隐爆角砾岩等密切有关。成矿物质和成矿流体主要来源于地幔,围岩地层只是提供了成矿的空间,不同类型的矿体之间呈"贯通式"的时间和空间关系,构成了一个统一的喜马拉雅期富碱斑岩-热液型金多金属成矿系统。先期形成矿床明显受后期岩浆热液的叠加改造,但矿化分布和成矿元素组合仍表现为以斑岩为中心,存在 CuAu(Mo)多金属→FeCuAuPbZn 多金属→AuPhZnAg 多金属的分带特征。从最早期含金铁矿床形成之后,原生金矿的次生富集和表生成矿作用就已开始,并形成不同成因类型的风化-堆积型金矿床。其中,古红色粘土型金矿床的成矿主要发生在始新世到渐新世,河-湖相古砂金矿床形成于23～5Ma 期间,红色粘土型(残坡积型)金矿床可从始新世一直延续至今。通过与区域斑岩成岩成矿演化时序的对比,提出与藏东-金沙江-哀牢山斑岩成矿带上的众多矿床一样,北衙矿田内的成岩成矿作也是喜马拉雅期印-亚陆陆碰撞造山带成岩成矿作用在东南缘构造转换带的远程效应,记录了印-亚大陆碰撞造山的详细过程。因而,该矿田深部及外围地区,仍存在巨大的找矿潜力。盐源-丽江断裂带可能也是一务与藏东-金沙江.哀牢山斑岩成矿带联系密切而又相对独立的富碱斑岩成矿带。
