Application of Spectral Angle Mapper Classification to Discriminate Hydrothermal Alteration in Southwest Birjand,Iran, Using Advanced Spaceborne Thermal Emission and Reflection Radiometer Image Processing     

Maryam ABDI  Mohammd H. KARIMPOUR 《《地质学报》英文版》2012,86(5):1289-1296

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.  相似文献   

Geology and Hydrothermal Alteration of the Duobuza Gold‐Rich Porphyry Copper District in the Bangongco Metallogenetic Belt,Northwestern Tibet     

Guangming LI  Jinxiang LI  Kezhang QIN  Ji DUO  Tianping ZHANG  Bo XIAO  Junxing ZHAO 《Resource Geology》2012,62(1):99-118

The Duobuza gold‐rich porphyry copper district is located in the Bangongco metallogenetic belt in the Bangongco‐Nujiang suture zone south of the Qiangtang terrane. Two main gold‐rich porphyry copper deposits (Duobuza and Bolong) and an occurrence (135 Line) were discovered in the district. The porphyry‐type mineralization is associated with three Early Cretaceous ore‐bearing granodiorite porphyries at Duobuza, 135 Line and Bolong, and is hosted by volcanic and sedimentary rocks of the Middle Jurassic Yanshiping Formation and intermediate‐acidic volcanic rocks of the Early Cretaceous Meiriqie Group. Simultaneous emplacement and isometric distribution of three ore‐forming porphyries is explained as multi‐centered mineralization generated from the same magma chamber. Intense hydrothermal alteration occurs in the porphyries and at the contact zone with wall rocks. Four main hypogene alteration zones are distinguished at Duobuza. Early‐stage alteration is dominated by potassic alteration with extensive secondary biotite, K‐feldspar and magnetite. The alteration zone includes dense magnetite and quartz‐magnetite veinlets, in which Cu‐Fe‐bearing sulfides are present. Propylitic alteration occurs in the host basic volcanic rocks. Extensive chloritization‐silicification with quartz‐chalcopyrite or quartz‐molybdenite veinlets superimposes on the potassic alteration. Final‐stage argillic alteration overlaps on all the earlier alteration. This alteration stage is characterized by destruction of feldspar to form illite, dickite and kaolinite, with accompanying veinlets of quartz + chalcopyrite + pyrite and quartz + pyrite assemblages. Cu coexists with Au, which indicates their simultaneous precipitation. Mass balance calculations show that ore‐forming elements are strongly enriched during the above‐mentioned three alteration stages.  相似文献   

松辽盆地白兴吐铀矿床成因讨论   总被引：1，自引：0，他引：1  

吴仁贵  徐喆  宫文杰  蔡建芳  宁君 《铀矿地质》2012,28(3):142-147

研究表明,白兴吐铀矿床具有以下几个特点:(1)高岭石化、碳酸盐化、黄铁矿化、水云母化、绢云母化和赤铁矿化等低温热液蚀变发育,铀矿物与热液成因的胶状-团块状和莓状黄铁矿、铁白云石、赤铁矿等共生;(2)工业铀矿化呈脉状,铀矿物组合以铀石为主,少量为沥青铀矿和含钛铀矿物;(3)碳(δ13C为-2.68‰～-10.49‰)、氧(δ18 O为-10.74‰～-17.1‰)、硫(δ34S为12.24‰～14.33‰和-33.06‰)等同位素特征呈现出与大气成因水、岩浆热作用、生物改造和硫酸盐、碳酸盐岩的溶解作用关系密切。因此,认为矿床的成因具有明显的氧化作用和热液作用双重特征,铀矿化是浅部氧化作用和深部流体作用的综合结果,即矿床具有渗入型与渗出型"双开放成矿系统"的成因特点。  相似文献   

相山铀矿田与斯特列利措夫铀矿田特征对比   总被引：1，自引：0，他引：1  

方锡珩 《铀矿地质》2012,(5):265-272

相山铀矿田和斯特列利措夫铀矿田均产于破火山口中,相山火山盆地的基底为震旦系变质岩,斯特列利措夫盆地的基底为多期活化的片麻状花岗岩。两盆地的破火山口盖层均为陆相火山岩系,相山破火山口火山岩系为酸性和中酸性岩,斯特列利措夫破火山口火山岩系则为酸性和基性火山岩呈互层产出。破火山口内的构造和蚀变作用发育程度存在明显差异,这是两个铀矿田成矿远景不同的主要原因。  相似文献   

全国铀矿资源潜力评价遥感数据处理与应用     

潘蔚  谢迎春  罗富生  刘建军  李瀚波  张建文  宫宝昌  谢联文  韩晓青  梁春丽  肖青  江露芳  樊芸湘  吴艳萍 《铀矿地质》2012,(6):383-387

通过遥感标准影像图制作、地质构造的解译推断和遥感蚀变信息提取等研究,将我国大陆划分为8大遥感特征区,对多条巨型控岩控盆断裂的分布特征进行修正和补充,在多个预测工作区中发现了隐伏断裂、火山机构、岩溶漏斗等,通过分析预测区内构造斜坡带和局部排泄带分布、岩体和断裂带的蚀变等成矿条件,结合铀矿地质信息预测了92片有利成矿区。  相似文献   

遥感蚀变异常在地质矿产勘查工作中的应用   总被引：2，自引：0，他引：2  

王宝林  朱锁  丛丽娟  高秀花 《华南地质与矿产》2011,(1):64-68

阐述利用遥感数据提取蚀变异常的机理、方法、数据源及在不同找矿阶段的应用.以内蒙古西部阿拉善左旗沙拉西别地区为例,讨论了遥感找矿的预测应用;以内蒙古西部朱拉扎嘎金矿为例,讨论了遥感找矿在详查工作阶段的应用.通过研究认为,遥感蚀变异常可以为野外勘探前期的预测阶段提供重要的找矿信息,为详查阶段提供精确的定位信息.遥感技术是贯...  相似文献   

安徽省南陵县吕山金矿床地质特征及找矿方向探讨   总被引：2，自引：0，他引：2  

谢祖军 《安徽地质》2011,21(3):180-185

安徽省南陵县吕山金矿床是一个受菱形地块剪切带控制的中低温变质热液中型矿床。矿化带、蚀变带严格受剪切带控制,通过矿床地质特征阐述、成矿物质来源、成矿物理化学条件、成矿环境、成矿温度、成矿压力和成矿深度、成因模式等分析,提出找矿方向。  相似文献   

Regional oxygen isotope systematics of felsic volcanics; a potential exploration tool for volcanogenic massive sulphide deposits in the Iberian Pyrite Belt     

C. Lerouge  Y. Deschamps  M. Joubert  E. Bchu  A. -M. Fouillac  J. A. Castro 《Journal of Geochemical Exploration》2001,72(3)

Regional oxygen isotopic sytematics have been performed mainly on the felsic volcanic footwall rocks of the orebodies but also on purple schist characteristic of the hanging wall series, around two giant VMS deposits in the Spanish Iberian Pyrite Belt, Riotinto and La Zarza. As the terranes of the Iberian Pyrite Belt, these two giant deposits have been affected by the Hercynian tectono-metamorphic events, strongly modifying their geometry. About 60 and 40 samples were collected over a 10×4 km² area at Riotinto and a 3×2 km² area at La Zarza, respectively. Whole-rock powders were analysed for oxygen by CO₂-laser fluorination. At both sites, a same type of low-δ¹⁸O anomaly down to +3.6‰, well differentiated from the regional background (up to 20‰), was identified near the orebodies. The lowest δ¹⁸O values (+4 to +11‰) correspond to the chlorite hydrothermal halo, essentially restricted to the feeder zones of the orebody. Intermediate δ¹⁸O values (+9 to +15‰) correspond to the sericite hydrothermal halo, mostly developed laterally to the orebody until 0.5–1 km. The regional background (+16 to +20‰) is represented by spilitised volcanic rocks. A same kind of low anomaly, but with less contrast, was defined in purple schist in the immediate hanging wall of the orebodies. All these results demonstrate that, despite high geometrical modifications of the orebodies related to the Hercynian tectonics, oxygen isotopic anomalies recorded by volcanic host rocks during the emplacement of the mineralising hydrothermal systems are still identified. This strongly suggests that oxygen isotopic systematics could be useful to identify target areas in the Iberian Pyrite Belt, as already demonstrated on other VMS targets in the world.  相似文献   

大别造山带超高压变质岩稳定同位素地球化学   总被引：3，自引：0，他引：3  

郑永飞  傅斌  龚冰 《安徽地质》2000,(3)

通过对大别造山带超高压变质岩的氢、氧和碳同位素地球化学研究，发现了显著的稳定同位素异常。结果对扬子板块向华北板块的俯冲提供了如下化学地球动力学制约： (1)北大别榴辉岩和基性麻粒岩与南大别超高压榴辉岩和片麻岩一样，具有较低的δ 18O值，表明它们在板块俯冲前经历了高温地表水热液蚀变，在超高压变质阶段流体以亏损 13C为特征； (2)部分低δ 18O值榴辉岩的共存矿物对之间保存了氧同位素平衡分馏，记录了榴辉岩相变质温度，指示这些榴辉岩在地幔的居留时间较短，折返初期的冷却速率较大； (3)退变质作用过程中存在显著的差异性氢氧同位素交换，早期阶段流体具有内部缓冲性质，而晚期则具有外部来源； (4)东大别大理岩显著富集 13C，反映出其母岩灰岩的沉积环境为封闭的大陆边缘盆地，西大别苏家河大理岩的δ 13C值接近于正常海相碳酸盐，指示其母岩形成环境为宽广开阔的海洋。  相似文献   

基于ASTER的康古尔塔格金矿带热液矿化蚀变信息提取          下载免费PDF全文

吴梦娟  周可法  王金林  王珊珊  张楠楠  周曙光 《地质找矿论丛》2016,31(4):555-563

新疆东天山的康格尔塔格金矿带矿产资源丰富,其重要控矿要素之一是韧性剪切带。文章使用ASTER数据提取该地区遥感矿化蚀变信息,并选择康古尔塔格金矿带的部分区域(因受数据获取限制,选择N41°38′—N42°20′、E91°20′—E92°20′范围)作为研究区。研究表明,区内矿化围岩蚀变特征明显,可通过分析研究区岩矿光谱特征以及ASTER数据光谱特征,分别选择假彩色合成、波段比值、特征向量主成分分析法(Crosta Technique)等图像处理技术来识别并提取研究区的矿化与蚀变矿物信息。结合ArcGIS将提取的矿化和蚀变信息与该地区的矿点与构造图层叠加,并对叠加成果图进行分析与对比,从叠加图中发现研究区中的金矿床沿韧性剪切带南侧的韧性剪切过渡带分布。通过阅读该地区的相关地质资料、成果文献等,对提取的矿化和蚀变信息进行验证;结果证明ASTER数据在相似干旱地区进行遥感蚀变信息提取具有可行性,此法用于相似地域找矿具有很好的应用前景。  相似文献