New strike‐slip faults and litho‐units mapped in Chitral (N. Pakistan) using field and ASTER data yield regionally significant results

Abstract

Several image‐processing techniques were used to map the Chitral area, northern Pakistan. In this area, the world's three greatest mountain ranges, the Himalayas, the Karakoram, and the Hindukush blocks, merge together. The area is extremely rugged; local relief is more than 2500 m. Many peaks are higher than 5000 m and Tirch Mir, 12 km north of the mapped area, is 7702 m. ASTER imagery and a digital elevation model developed from the ASTER data are used for decorrelation stretches, principal components analyses, and spectral angle mapper (SAM) classifications. These image‐processing techniques were used to characterize the lithology and structure of the area. This study produced the most current geologic map for fully understanding the interaction between the Kohistan, western Karakoram, and eastern Hindukush blocks along the Shyok Suture and the Tirch Mir Fault. We utilized previously published geologic maps and fieldwork of the area to validate the image classifications. We have discovered two new strike‐slip faults, and recent earthquake activity along the faults indicates that the faults are active. Recognition of these faults has potential tectonic significance, as they may be associated with the Chaman Fault – a major transcurrent fault linking the Indian plate with Pamir. Furthermore, we have discovered an anomalous mineralized zone and further work may uncover new mineral deposits.

Acknowledgements

This work is funded by a National Science Foundation, NDF (OISE) award No. 0350847 award to Khan. We thank Drs Tahir Shah and Liaqat Ali (University of Peshawar) for their help in fieldwork. Dr Kevin Burke and Mike Murphy are thanked for fruitful discussions on the regional tectonics.