Middle to late Eocene exhumation of the Greater Himalayan Sequence in the Central Himalayas: Progressive accretion from the Indian plate
| Autor: | Carosi R.[1], Montomoli C.[2, Iaccarino S.[2], Massonne H.-J.[4], Rubatto D.[5, Langone A.[7], Gemignani L.[8], Visonà D.[9] |
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| Přispěvatelé: | Geology and Geochemistry |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
U-Pb geochronology
010504 meteorology & atmospheric sciences P-T-t paths Metamorphic rock Himalaya Metamorphism monazite geochronology Exhumation P-T-t-D paths 010502 geochemistry & geophysics 01 natural sciences 550 Earth sciences & geology Main Central Thrust Kalopani shear zone SDG 14 - Life Below Water pseudosections Tectonics Himalaya Greater Himalayan Sequence metamorphism P-T-t paths U-Pb geochronology exhumation tectono-metamorphic discontinuities Petrology Geomorphology 0105 earth and related environmental sciences Shearing (physics) Geothermobarometry Tectonics Greater Himalayan Sequence Geology Crust Kali Gandaki valley metamorphism tectono-metamorphic discontinuities Geochronology Shear zone in-sequence shearing |
| Zdroj: | Geological Society of America bulletin 128 (2016): 1571–1592. doi:10.1130/B31471.1 info:cnr-pdr/source/autori:Carosi R.[1], Montomoli C.[2,3], Iaccarino S.[2], Massonne H.-J.[4], Rubatto D.[5,6], Langone A.[7], Gemignani L.[8], Visonà D.[9]/titolo:Middle to late Eocene exhumation of the Greater Himalayan Sequence in the Central Himalayas: Progressive accretion from the Indian plate/doi:10.1130%2FB31471.1/rivista:Geological Society of America bulletin/anno:2016/pagina_da:1571/pagina_a:1592/intervallo_pagine:1571–1592/volume:128 Carosi, R, Montomoli, C, Laccarino, S, Massonne, H J, Rubatto, D, Langone, A & Gemignani, L 2016, ' Middle to late Eocene exhumation of the Greater Himalayan Sequence in the Central Himalayas: Progressive accretion from the Indian plate ', Geological Society of America Bulletin . https://doi.org/10.1130/B31471.1 Geological Society of America Bulletin. Geological Society of America |
| ISSN: | 1943-2674 |
| DOI: | 10.1130/B31471.1 |
| Popis: | We investigated a contractional shear zone located in central Nepal, known as Kalopani shear zone. This high-temperature shear zone triggered the early exhumation of the metamorphic core in the Himalayan belt and deeply affected the tectono-metamorphic history of the crystalline rocks soon after the collisional stage. Pseudosection modeling and inverse geothermobarometry reveal that rocks involved in the Kalopani shear zone experienced pressure-temperature conditions between 0.60 and 0.85 GPa and 600 and 660 °C. U-Th-Pb in situ laser ablation– inductively coupled plasma–mass spectrometry and sensitive high-resolution ion microprobe dating on monazite points to retrograde metamorphism related to the Kalopani shear zone starting from ca. 41 to 30 Ma. The kinematics of the Kalopani shear zone and associated erosion and/or tectonics caused the middle-late Eocene exhumation of the Greater Himalayan Sequence in the hanging wall of the Kalopani shear zone at least 9 m.y. before the activities of the middle tectonicmetamorphic discontinuity in the Greater Himalayan Sequence (High Himalayan discontinuity), the Main Central thrust, and the South Tibetan detachment. Structural data, metamorphic conditions, and geochronology from the Kalopani shear zone, compared to those of other major tectonic discontinuities active within the Greater Himalayan Sequence in the Kali Gandaki valley, indicate that shear deformation and exhumation were not synchronous all over the Greater Himalayan Sequence but migrated downward and southward at different lower levels. These processes caused the exhumation of the hanging wall rocks of the activated shear zones. The main consequence is that exhumation has been driven since the middle-late Eocene by an in-sequence shearing mechanism progressively involving new slices of the Indian crust, starting from the metamorphic core of the orogen and later involving the outer portions of the belt. This challenges the common view of exhumation of the Greater Himalayan Sequence mainly driven by the coupled activity of Main Central thrust and South Tibetan detachment between ca. 23 and 17 Ma. |
| Databáze: | OpenAIRE |
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