Gneiss Dome Formation in the Himalaya and southern Tibet
Published:October 08, 2019
Micah J. Jessup, Jackie M. Langille, Timothy F. Diedesch, John M. Cottle, 2019. "Gneiss Dome Formation in the Himalaya and southern Tibet", Himalayan Tectonics: A Modern Synthesis, P. J. Treloar, M. P. Searle
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Gneiss domes in the Himalaya and southern Tibet record processes of crustal thickening, metamorphism, melting, deformation and exhumation during the convergence between the Indian and Eurasian plates. We review two types of gneiss domes: North Himalayan gneiss domes (NHGD) and later domes formed by orogen-parallel extension. Located in the southern Tibetan Plateau, the NHGD are cored by granite and gneiss, and mantled by the Tethyan sedimentary sequence. The footwall of these were extruded southwards from beneath the Tibetan Plateau and subsequently warped into a domal shape. The second class of domes were formed during displacement on normal-sense shear zones and detachments that accommodated orogen-parallel extension during the Late Miocene. In some cases, formation of these domes involved an early stage of southwards-directed extrusion prior to doming. We review evidence for orogen-parallel extension to provide context for the formation of these gneiss domes. Compilations of pressure–temperature–time–deformation data and temperature–time paths indicate differences between dome types, and we accordingly propose new terminology. Type 1 domes are characterized by doming as an artefact of post-high-temperature exhumation processes in the Middle Miocene. Type 2 domes formed in response to exhumation during orogen-parallel extension in the Late Miocene that potentially post-dates south-directed extrusion.
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Himalayan Tectonics: A Modern Synthesis
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The Himalaya–Karakoram–Tibet mountain belt resulted from Cenozoic collision of India and Asia and is frequently used as the type example of a continental collision orogenic belt. The last quarter of a century has seen the publication of a remarkably detailed dataset relevant to the evolution of this belt. Detailed fieldwork backed up by state-of-the-art structural analysis, geochemistry, mineral chemistry, igneous and metamorphic petrology, isotope chemistry, sedimentology and geophysics produced a wide-ranging archive of data-rich scientific papers. The rationale for this book is to provide a coherent overview of these datasets in addressing the evolution of the mountain ranges we see today.
This volume comprises 21 specially invited review papers on the Himalaya, Kohistan arc, Tibet, the Karakoram and Pamir ranges. These papers span the history of Himalayan research, chronology of the collision, stratigraphy, magmatic and metamorphic processes, structural geology and tectonics, seismicity, geophysics, and the evolution of the Indian monsoon. This landmark set of papers should underpin the next 25 years of Himalayan research.