40Ar-39Ar dating of detrital white micas, petrography and heavy mineral analysis andwhole-rock geochemistry has been applied to three time-equivalent sections through the SiwalikGroup molasse in SW Nepal [Tinau Khola section (12-6Ma), Surai Khola section (12-1Ma) andKarnali section (16-5Ma)]. 40Ar-39Ar ages from 1415 single detrital white micas show a peak of ages between 20 and 15 Ma for all the three sections, corresponding to the period of most extensive exhumation of the Greater Himalaya. Lag times of less than 5 Myr persist until 10 Ma, indicating Greater Himalayan exhumation rates of up to 2.6 mmyear-1, using one-dimensional thermal modelling.There are few micas younger than 12Ma, no lag times of less than 6Myr after 10Ma and whole-rock geochemistry and petrography show a signi¢cant provenance change at 12Ma indicating erosion from the Lesser Himalaya at this time.These changes suggest a switch in the dynamics of the orogen that took place during the12-10Ma period whereby most strain began to be accommodated by structures within the Lesser Himalaya as opposed to the Greater Himalaya. Consistent data from all three Siwalik sections suggest a lateral continuity in tectonic evolution for the central Himalayas

Szulc, A., Najman, Y., Sinclair, H., Pringle, M., Bickle, M., Chapman, H., et al. (2006). Tectonic evolution of the Himalaya constrained by detrital 40Ar-39Ar, Sm-Nd and petrographic data from the Siwalik foreland basin succession, SW Nepal. BASIN RESEARCH, 18(4), 375-391 [10.1111/j.1365-2117.2006.00307.x].

Tectonic evolution of the Himalaya constrained by detrital 40Ar-39Ar, Sm-Nd and petrographic data from the Siwalik foreland basin succession, SW Nepal

GARZANTI, EDUARDO;ANDO', SERGIO;
2006

Abstract

40Ar-39Ar dating of detrital white micas, petrography and heavy mineral analysis andwhole-rock geochemistry has been applied to three time-equivalent sections through the SiwalikGroup molasse in SW Nepal [Tinau Khola section (12-6Ma), Surai Khola section (12-1Ma) andKarnali section (16-5Ma)]. 40Ar-39Ar ages from 1415 single detrital white micas show a peak of ages between 20 and 15 Ma for all the three sections, corresponding to the period of most extensive exhumation of the Greater Himalaya. Lag times of less than 5 Myr persist until 10 Ma, indicating Greater Himalayan exhumation rates of up to 2.6 mmyear-1, using one-dimensional thermal modelling.There are few micas younger than 12Ma, no lag times of less than 6Myr after 10Ma and whole-rock geochemistry and petrography show a signi¢cant provenance change at 12Ma indicating erosion from the Lesser Himalaya at this time.These changes suggest a switch in the dynamics of the orogen that took place during the12-10Ma period whereby most strain began to be accommodated by structures within the Lesser Himalaya as opposed to the Greater Himalaya. Consistent data from all three Siwalik sections suggest a lateral continuity in tectonic evolution for the central Himalayas
Articolo in rivista - Articolo scientifico
Himalaya; 40Ar-39Ar; Sm-Nd; bulk petrography; heavy minerals
English
2006
18
4
375
391
none
Szulc, A., Najman, Y., Sinclair, H., Pringle, M., Bickle, M., Chapman, H., et al. (2006). Tectonic evolution of the Himalaya constrained by detrital 40Ar-39Ar, Sm-Nd and petrographic data from the Siwalik foreland basin succession, SW Nepal. BASIN RESEARCH, 18(4), 375-391 [10.1111/j.1365-2117.2006.00307.x].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/28658
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