Collision Tectonics

As an outgrowth of IGCP430 we constructed a multi-disciplinary GIS database (TETHYS) applied (as a case study) as a tool for studying ongoing and recent responses to the collisions of northward-drifting Gondwana fragments with continental Eurasia. The database integrates digitized geological, structural, geodetic, remote sensing, sample-based and geochemical, isotopic, geophysical, and radiometric age data.

In the context of this project, we have focused research on the timing of the Indo-Asia collision and its relatively complicated expression in the western Himalayas, our preliminary results indicating the presence of a discrete Kohistan-Ladakh block between the two major continents. While the inferred respective collisions of this block with India and Asia have been assumed to have been sequential, the precise collision sequence remains unclear. As a means of clarifying this issue, we have undertaken to combine field, remote sensing, geochronologic, geochemical, and isotopic studies of related magmatic products in northern Kohistan, along with a reassessment of published paleomagnetic data.

On the basis of work so far completed we have developed a provisional model suggesting that Kohistan/Ladakh collided with India prior to the terminal India-Eurasia collision, the latter defined by the Shyok suture. Meanwhile, utilizing ASTER remote sensing data for remote (and arid) parts of western Pakistan, as a means of discriminating major ophiolite lithologic constituents, we are creating a series of detailed ophiolite maps which, in combination with published and ongoing geochemical studies, appear to indicate that the ophiolites represent intra-oceanic forearc complexes, or fragments thereof, associated with a series of back-arc opening episodes.

Sources of Funding

National Science Foundation (EAR)

National Science Foundation (OISE)

References and Publications

Xiong, Y., Khan, S. D., Mahmood, K., and Sisson, J. 2011. Lithological mapping of Bela Ophiolite with remote sensing data. International Journal of Remote Sensing, 32(16), 4641-4658.

Khan, S. D., Walker, D. J., Hall, S., Burke, K., Shah, M. T., and Stockli, L. 2009. Did Kohistan-Ladakh island arc collide first with India? Geological Society of America Bulletin, 121 (3/4), 366-384.

Khan, S. D., and Mahmood, K., 2008."The Application of Remote Sensting Techniques to the Study of Ophiolites. Earth-Science Reviews.

Khan, S. D., Heggy, E., Fernandez, J. 2007. Mapping exposed and buried lava flows using synthetic aperture radar and ground-penetrating radar in Craters of the Moon lava field. Geophysics, 72(6), 161-174.

Khan, S. D., Flower, M. F. J., Sultan, M. I. Sandvol. E. 2006. Introduction to TETHYS- An Interdisciplinary GIS Database for Studying Continental Collisions. Journal of Asian Earth Sciences, 26(6), 613-625.

Khan, S. D., Glenn, N. 2006. New Strike Slip Faults and Litho-Units Mapped in Chitral (N. Pakistan) Using Field and ASTER Data Yield Regionally Significant Results. International Journal of Remote Sensing, 27(2), 4495-4512.