Geological Interpretation And Mineralization Altered Information Extraction With Remote Sensing Images In Nima Area, Tibet

The study area located in the middle of Tibet autonomous region,is an important part of Gangdise Metallogenic Belt. Although it is very rich in available resources,especially metal mine,the entire degree of its exploitation and utilization is still low, because of the bad traffic,tough natural conditions and poor geological survey work in large scale.Therefore,it is very necessary to investigate and study the geology in a large scale in the study area. As the metal mine always contains a large amount of hydroxyl and ferric ions,mineralization altered information anomaly can be characterized to some extent by the hydroxyl and iron anomaly.Based on remote sensing geology theory and the research project, and on the basis of comprehensive collection of the study area and other relevant information, this paper conducts a geological interpretation and mineralization altered information extraction in the sparsely covered and well-exposed study area by using Landsat-7 Enhanced Thematic Mapper Plus(ETM+),Landsat 8 Operational Land Imager(OLI) and Worldview-2 data.Finally, some results have been achieved as follows:(1)1:50,000 geological interpretation has been done. Taking Worldview-2 image as the main data source,this paper selects the optimal band combination image(Worldview-2, 843) for visual interpretation after pretreatment and enhancement of the image. At the same time, ETM+ data is selected to assist structural interpretation Finally, the stratigraphic, lithologic and linear structural information of the study area are obtained. The spatial distribution characteristics of geological structure in the study area was find out.(2)Method "Masking + Independent Component Analysis " has been applied to extract iron alteration and hydroxylation alteration respectively. Refered to the metal deposits data, evaluates the alteration information effectiveness. The result reveals that extraction of anomalies are coincident with the ore-bearing strata.It is effective.(3)A contrast is taken between the two iron alteration extracted by OLI data and Worldview-2 data.Then the author comes to the conclusion that: on the one hand, two kinds of data extraction results match each other,which are both controlled by the regional tectonic activity and intrusive igneous rock.On the other hand, due to the presence of mixed pixel problems, results extracted from OLI data contains more pseudo information. However,Worldview-2 data, which has both Spectral advantages in the visible range and high surface detail detection capability, not only can identify a large range of mineralization anomalies, but also recognize the smaller,which presents patchy distribution in space.Compared with the low-middle resolution data, iron alteration in the high resolution image is described in more detail. Worldview-2 data has a greater advantage in the extraction of iron alteration information.