Jessup,M.J., Newell,D.L., Cottle,J.M., Berger,A.L. and Spotila,J.A.(2008): Orogen-parallel extension and exhumation enhanced by denudation in the trans-Himalayan Arun River gorge, Ama Drime Massif, Tibet-Nepal. Geology, 36(7), 587-590.

『チベット−ネパールのアマドリム山塊のヒマラヤを貫くアルン峡谷における削剥によって促進された造山帯に平行な拡大と浸食作用による再露出』


Abstract
 Focused denudation and mid-crustal flow are coupled in many active tectonic settings, including the Himalaya, where exhumation of mid-crustal rocks accommodated by thrust faults and low-angle detachment systems during crustal shortening is well documented. New structural and (U-Th)/He apatite data from the Mount Everest region demonstrate that the trans-Himalayan Ama Drime Massif has been exhumed at a minimum rate of 〜1 mm/yr between 1.5 and 3.0 Ma during orogen-parallel extension. The Ama Drime Massif offsets the South Tibetan detachment system, and therefore the South Tibetan detachment system is no longer capable of accommodating south-directed mid-crustal flow or coupling it with focused denudation. Previous investigations interpreted the NNE-SSW-striking shear zone on the west side of the Ama Drime Massif as the Main Central thrust zone; however, our data show that the Ama Drime Massif is bounded on either side by 100-300-m-thick normal-sense shear zone and detachment systems that are kinematically linked to young brittle faults that offset Quaternary deposits and record active orogen-parallel extension. When combined with existing data, these results suggest that the Ama Drime Massif was exhumed during orogen-parallel extension that was enhanced by, or potentially coupled with, denudation in the trans-Himalayan Arun River gorge. This model provides important insights into the mechanisms that exhumed trans-Himalayan antiformal structures during orogen-parallel extension along the southern margin of the Tibetan Plateau.

Keywords: exhumation; mid-crustal flow; extension; denudation; Himalaya; Tibetan Plateau』

Introduction
Previous interpretations of the Ama Drime Massif
Structural evolution and exhumation of the Ama Drime Massif
Discussion and conclusions
Acknowledgments
References cited


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