Study of methods for extraction of remote sensing information of rocks and altered minerals from Luobusha ophiolite in east Tibet

Abstract

With Luobusha ophiolite as the study case and on the basis of remote sensing data of ETM and ASTER,the authors used the ratio and principal component analysis methods to extract the altered mineral information of iron-stain alteration(magnetite and olivine) and that of hydroxyl alteration(serpentine and chlorite) respectively so as to study the utilization of remote sensing technology to recognize and extract the rock and altered mineral information of ophiolite.In addition,pure pixel index(PPI) method was employed to extract endmember spectrum.In combination with the available field lithologic information,dunite was distinguished from peridotite by methods of spectral angle mapper(SAM) and spectral feature fitting(SFF).On such a basis,the spatial distribution of Luobusha ophiolite rock and its main altered minerals was determined.The results of comparative analysis show that rock and mineral information extracted by different methods and different data types can be verified reciprocally.The extracted information of dunite and peridotite is well consistent with the extracted information of iron-stain alteration and hydroxyl alteration and is also coincident with the result of the ground survey.The results of this study show that the methods proposed in this paper are feasible for extraction of ophiolite rock and mineral remote sensing information,and have good geological effect.