The gravity field of the Karakoram Mountain Range and surrounding areas
Published:January 01, 2000
A. Caporali, 2000. "The gravity field of the Karakoram Mountain Range and surrounding areas", Tectonics of the Nanga Parbat Syntaxis and the Western Himalaya, M. Asif Khan, Peter J. Treloar, Michael P. Searle, M. Qasim Jan
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A ‘blank on the map’ only 60 years ago, the Karakoram Range has been explored and surveyed with greater difficulty than the Himalaya and Tibet due to its rugged terrain and extensive glaciation. In the past ten years we have succeeded in doubling the number of gravity stations. A substantial improvement in coverage and overall quality was obtained by concentrating on previously unsurveyed areas and by validating older data with more accurate measurements. Our data were merged with earlier data, converted to full Bouguer anomalies and gridded. The resulting Bouguer anomaly map defines very precisely the gravimetric low associated with the Nanga Parbat-Haramosh syntaxis, and the huge negative anomalies between the Karakoram Fault and the Main Karakoram Thrust. Large negative values are now visible also in the Ghujerab-Khunjerab areas. Correlation of the topography and Bouguer anomaly shows that a plate of flexural rigidity with D = 2 × 1024 Nm fits the coherence data in the Karakoram at all but two distinct frequency ranges centred at wavelengths of 80 and 300 km. In a rheologically layered lithosphere developing a buckling instability under horizontal compression, the observed spectral features of the topography and Bouguer gravity anomalies constrain the depth of the competent layers to be in the range 13–20 km and 50–75 km respectively.
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Tectonics of the Nanga Parbat Syntaxis and the Western Himalaya
The western syntaxis of the Himalaya is one of the most exciting frontiers of continental tectonis studies. The region around the mountain of Nanga Parbat has some of the highest peaks, deepest valleys and highest uplift, exhumation and erosion rates known on earth. Surrounding regions include the Hindu Kush and Karakoram mountains (Asian plate), the Kohistan island arc and the Ladakh and Zanskar ranges of the western Himalaya (Indian plate). This volume includes 24 papers on all these regions as well as five new fold-out maps of the eastern Hindu Kush, the Spontang Ophiolite region of Ladakh, part of the west margin of the Indian plate, the Indus syntaxis in Pakistan and the Bouguer gravity anomalies in Pakistan.