TY  - JOUR
A1  - Stübner, Konstanze
A1  - Grujic, Djordje
A1  - Dunkl, Istvan
A1  - Thiede, Rasmus  Christoph
A1  - Eugster, Patricia
T1  - Pliocene episodic exhumation and the significance of the Munsiari thrust in the northwestern Himalaya
JF  - Earth & planetary science letters
N2  - The Himalayan thrust belt comprises three in-sequence foreland-propagating orogen-scale faults, the Main Central thrust, the Main Boundary thrust, and the Main Frontal thrust. Recently, the Munsiari–Ramgarh–Shumar thrust system has been recognized as an additional, potentially orogen-scale shear zone in the proximal footwall of the Main Central thrust. The timing of the Munsiari, Ramgarh, and Shumar thrusts and their role in Himalayan tectonics are disputed. We present 31 new zircon (U–Th)/He ages from a profile across the central Himachal Himalaya in the Beas River area. Within a ∼40 km wide belt northeast of the Kullu–Larji–Rampur window, ages ranging from to constrain a distinct episode of rapid Pliocene to Present exhumation; north and south of this belt, zircon (U–Th)/He ages are older ( to ). We attribute the Pliocene rapid exhumation episode to basal accretion to the Himalayan thrust belt and duplex formation in the Lesser Himalayan sequence including initiation of the Munsiari thrust. Pecube thermokinematic modelling suggests exhumation rates of ∼2–3 mm/yr from 4–7 to 0 Ma above the duplex contrasting with lower (<0.3 mm/yr) middle-late Miocene exhumation rates. The Munsiari thrust terminates laterally in central Himachal Pradesh. In the NW Indian Himalaya, the Main Central thrust zone comprises the sheared basal sections of the Greater Himalayan sequence and the mylonitic ‘Bajaura nappe’ of Lesser Himalayan affinity. We correlate the Bajaura unit with the Ramgarh thrust sheet in Nepal based on similar lithologies and the middle Miocene age of deformation. The Munsiari thrust in the central Himachal Himalaya is several Myr younger than deformation in the Bajaura and Ramgarh thrust sheets. Our results illustrate the complex and segmented nature of the Munsiari–Ramgarh–Shumar thrust system.
KW  - Himalaya
KW  - Himachal Pradesh
KW  - Munsiari thrust
KW  - thermochronology
KW  - thermokinematic modelling
KW  - Pliocene
Y1  - 2017
U6  - https://doi.org/10.1016/j.epsl.2017.10.036
SN  - 0012-821X
SN  - 1385-013X
VL  - 481
SP  - 273
EP  - 283
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Hansman, Reuben J.
A1  - Ring, Uwe
A1  - Thomson, Stuart N.
A1  - den Brok, Bas
A1  - Stuebner, Konstanze
T1  - Late Eocene Uplift of the Al Hajar Mountains, Oman, Supported by Stratigraphy and Low-Temperature Thermochronology
JF  - Tectonics
N2  - Uplift of the Al Hajar Mountains in Oman has been related to either Late Cretaceous ophiolite obduction or the Neogene Zagros collision. To test these hypotheses, the cooling of the central Al Hajar Mountains is constrained by 10 apatite (U-Th)/He (AHe), 15 fission track (AFT), and four zircon (U-Th)/He (ZHe) sample ages. These data show differential cooling between the two major structural culminations of the mountains. In the 3km high Jabal Akhdar culmination AHe single-grain ages range between 392 Ma and 101 Ma (2 sigma errors), AFT ages range from 518 Ma to 324 Ma, and ZHe single-grain ages range from 62 +/- 3Ma to 39 +/- 2 Ma. In the 2 km high Saih Hatat culmination AHe ages range from 26 +/- 4 to 12 +/- 4 Ma, AFT ages from 73 +/- 19Ma to 57 +/- 8 Ma, and ZHe single-grain ages from 81 +/- 4 Ma to 58 +/- 3 Ma. Thermal modeling demonstrates that cooling associated with uplift and erosion initiated at 40 Ma, indicating that uplift occurred 30 Myr after ophiolite obduction and at least 10 Myr before the Zagros collision. Therefore, this uplift cannot be related to either event. We propose that crustal thickening supporting the topography of the Al Hajar Mountains was caused by a slowdown of Makran subduction and that north Oman took up the residual fraction of N-S convergence between Arabia and Eurasia.
KW  - thermochronology
KW  - Oman
KW  - uplift
KW  - mountains
KW  - fission-track
KW  - (U-Th)
KW  - He
Y1  - 2017
U6  - https://doi.org/10.1002/2017TC004672
SN  - 0278-7407
SN  - 1944-9194
VL  - 36
SP  - 3081
EP  - 3109
PB  - American Geophysical Union
CY  - Washington
ER  -