大型斑岩铜矿的遥感信息探讨

遥感影像解译的不同规模级别的线性构造、不同类型的环形构造和线-环组合类型以及色彩异常影像是寻找斑岩铜矿,特别是大型斑岩铜矿床最有用的遥感标志。1.砂岩铜矿的规模直接与不同规模不同级别的线性构造相联系区域性斑岩铜矿带直接受大型区域线性构造带和它们的汇聚格局控制,这种区域线性构造带多为区域压性壳断裂或超壳断裂,在遥感图像上常显示为浅色带,其长度超过100km,被称为主干边缘线性构造带(处于隆起单元向坳陷单元过渡部位,靠近隆起单元一侧).此外,一系列次级线性构造往往与主干边缘线性构造成一定角度相交,共同形成一种贯通性构造,在遥感图像上也常显示为浅色线;并直接控制斑岩铜矿田的分布和矿床的定位,被称为横向线性构造,长度一般1km-100km,主要包括三种类型(略),均显示张性特征。事实上,与斑岩铜矿有关的蚀变矿化直接受控于更低级别的线性构造(断裂和裂隙),它们常构成统一的环状和放射状断裂、裂隙系统。2.不同组合的多层环形影像是斑岩铜矿的不同呈矿环块构造的映像几乎所有的斑岩铜矿都与环块构造有关,特别是Ⅲ或Ⅳ级环块(直径50km-500km,包括环隆、环陷及褶皱-断裂环块等).它们控制了斑岩铜矿的定位。

THE PROBING OF REMOTE SENSING INFORMATION IN LARGE SCALE PORPHYRY COPPER

In remote sensing image interpretation, different grades of linear structure, different types of circular structure, different combinations of linear and circular structure, and color anomaly are the most useful ioformetion for porphyry copper.1. The Scale of Porphyry Copper Connect Directly with Different Grades of Linear Structure Regional porphyry copper zones are controlled directly by large regional linear structure zones and their convergent patters. The regional linear structure zones which show light color zones in image usually are regional compression crustal or over-crustal faults, over 100km in length,called peripheral-major linear structure zones. In addition, a lot of secondary linear structures which intersect with the peripheral-major structures in suitable angle, form joining-up structures, of ten also show light color in image, directly control ore field distribution and deposit location. They are called crosswise linear structure, generally from 1 to 100km in length, mainly include 3 types and show tension characteristics. In fact, more lower grade of linear structures (faultsand fractures) which usually form circle, radiate like fault and fracture system, directly control alteration and mineralization related to the perphyry copper.2. Different Assemblages of Multilayer Circular Image Feature Reflect on Different Circular Structure Blocks Contained Porphyry Copper Almost all porphyry coppers relate to circular blocks, especially to Ⅲ or Ⅳ grade circular structure blocks (D. From 50 to 500km), including upwarped circular blocks, downwarped circular blocks and foldcircular blocks, fault circular blocks etc.. They control the location of porphyry copper. In igneous circular blocks, coppers usually lie in: (1) On the demarcation surface or the center of multilayer circles reflected on batholith and small hidden rock body; (2) Inside or on the edge of multilayer circles reflected on crater and crypto-explosive breccia pipe; (3) In alteration zone, the circular features show the volcanic rock, intrusive rock body, volcanic apparatus and alteration envelope.3. Linear-Circular Structures Jointly Control the Distribution of Deposit or Field of Porphyry Copper The position of linear structure intersecting or contacting with circular block structtire generally indicates the canal of ore fluid and the space of ore capacity, as a result, it control the distribution of deposit or field of porphyry copper. They mainly include: (1) The action that multilayer inter-contacting circles intersect with linear structure; (2) The out -circle section of multilayer concentric circles, haled in the angle area intersected by two groupo of linear structures;(3) The demarcation surface or the center of multi- layer near concentric circlar block, located in the area intersected by two groups of linear structures; (4) In the big circle with small intercontacling circles, two groups of linear structures intersect, a series of more small circles separately appear along the two groups of linear structures in string or belt, the deposit appears in the edges of the more small circles; (5) Two groups of linear structures intersect in double concentic circles, pluy porrphyry copper appears in the edge of small inter circle.4. The boor Anomaly of Circle and Circular Belt Present Alteration Related tO the Mineralization of Porphyry Copper TM and MSS images processed by computer can clearly show the abnormal color circular belt caused by alteration related to porphyry copper. For example, in TM 6/7 (red), 6/5 (green),6/4 (blue)] image of Wunugetushan quartz-sericitization allerations in which deposit is formed present which circular belt, and illite hydromica alterations in light cyan is outer-circular belt,aroud the which one.