MULTISPECTRAL REMOTE-SENSING OF THE GOSSES BLUFF IMPACT CRATER, CENTRAL AUSTRALIA (NT) BY USING LANDSAT-TM AND ERS-1 DATA

Remote sensing techniques offer a unique chance to analyse and to map planetary impact craters in a relatively short time and at low cost. I n the past, studies were mainly restricted to the search for possible impact sites (e.g. Earth) or for age determinations (crater statistics ). On the basis of Landsat-TM 5 and ERS-1 data the lithological and st ructural characteristics of the complex Gosses Bluff impact crater (Au stralia) has been analysed in order to obtain reasonable lithological classification approaches. The fundamental statistical selection rule for pure colour composites of original TM-data was the calculation of the optimum index factor (OIF), or for hybrid colour composites (e.g. a combination of a original TM-band with a principal component and a r atio) using the widest statistical variance for each dataset. Addition al spectral measurements were carried out for each representative rock unit of the crater specific zones in order to estimate the quality of supervised maximum-likelihood computer classifications for geological mapping. Complementary ERS-1 altimetric data were utilized to study t he resulting crater morphology as an expression of the displacement ef fects and some structural features of the target caused by the crateri ng process (e.g. diameter, fracture pattern, ejecta displacement, etc. ).