Erosion and asymmetric relief evolution of the Central Asian Pamir Plateau
Zusammenfassung der Projektergebnisse
I did not achieve and had to modify the research goals – but reached, important, interesting, and provocative results. The new data will help to quantify temporal and spatial tectonic and uplift history of the northwest Pamir – where literally no data have been available prior to this study. We infer from a combination of available and new thermochronology, channel steepness and local relief patterns, as well as the elevation of perched low-relief erosion surfaces that rock uplift of the western Pamir margin in ongoing since less than 10 Ma, in agreement with earlier suggestions, but missing data constraint. GPS data indicate that this is not ongoing today. This pattern implies ~1.5 km surface uplift on, or beneath Vakhsh Thrust System (VTS) and Darvaz Fault System (DFS). The regional distribution river profiles and perched low-relief surface indicate that the Darvaz and Peter- 1.-Range uplifted in large parts together. 1. (a) Perched low relief landscapes document along strike gradients surface uplift along western and northwest Pamir Plateau margin. (b) Within the steep morphology of the uplifted landscapes of central northern Pamir margin none of the transient landscapes are preserved, whereas, in contrast, in the southwest, these transients landscape are still extensively preserved. (c) Another along strike change are documented by the fact that the perched low relief landscapes are observed both in footwall and hangingwall of the Darvaz-Fault stystem along the northern Pamir, whereas along its western margin they are restricted to hanging wall of Darvaz-Fault system, where Darvaz Fault system forms today the main topographic margin. This indicates strong along strike temporal variation fault activity and topographic growth of Pamir Plateau. 2. Along longitudinal river profiles of tributary valley of the main strem river, such as Panj- and Vakhsh-River, we observed pronounced knick zones, with oversteeped and convex profiles; suggest rapid regional base-level drop relative to the transient landscapes. These major knick zones are both observed within the Darvaz- and Peter.1-Range suggesting they evolved during the same uplift event. They imply that the Darvaz and Peter.1.-Range where uplifted synchronously in northwest Pamir. 3. Recently published geodectic data and seismotectonic suggest narrow and sharp crustal shortening gradient along northern Pamir margin supporting the existence of crustal ramp. Seismicity in concentrated in and at the base of a southward deepening, ~9-15-km-thick wedge. These finding agree well our finding of reset Z-He ages, indicating that the present deformation is ongoing since a least 6 Ma. New lowtemperature chronology data with ages as young as 3 - 5 Ma, such as new zircon (U- Th)/He and apatite fission track data suggest rapid cooling, uplift and the existence of deep seated crustal ramps within and between the Darvaz-Fault-System (DFZ) and Vakhsh Thrust System (VTS) since the Late Miocene. In contrast, along the western margin the Darvaz-Fault-System coincides with major topographic boundary, the plateau margin. The discovered perched low-relief landscapes indicate recent uplift of this segment, implying a certain transpressiv component during displacement along the DFZ. In contrast, within the north Pamir the perched low-relief landscapes extend across the DFZ and strong strike-slip component has already been described earlier. However, reset Z-He ages document significant exhumation during deformation with the Peter-1.-Range. 4. New zircon (U-Th/He) ages ranging between ~25-20 Ma document crustal cooling and uplift event of the Darvaz Range. Observed paleo-relief have been in the range of at >1.5 km, prior to its coverage with Neogene sediments. This indicates that the Darvaz range has formed a pronounced and uplifted feature of the northern Pamir during the Early Miocene, before it has been strongly eroded and finally covered by Neogene sediment. These findings have important implication in the context of the recently discussed geodynamic models inferred from excellent new geophysical datasets.
Projektbezogene Publikationen (Auswahl)
- (2013). Late Cenozoic extension and crustal doming in the India-Eurasia collision zone: New thermochronologic constraints from the NE Chinese Pamir, Tectonics, V32/3 p. 763-779
Thiede, R.C., E. R. Sobel, J. Chen, L. M. Schoenbohm, D. F. Stockli, M. Sudo, and M. R. Strecker
(Siehe online unter https://doi.org/10.1002/tect.20050) - (2016). Climate-driven sediment aggradation and incision since the late Pleistocene in the NW Himalaya, India. Earth and Planetary Science Letters, 449, pp.321-331
Dey, S., Thiede, R.C., Schildgen, T.F., Wittmann, H., Bookhagen, B., Scherler, D., Jain, V. and Strecker, M.R.
(Siehe online unter https://doi.org/10.1016/j.epsl.2016.05.050) - (2016). Holocene internal shortening within the northwest Sub-Himalaya: Out-of-sequence faulting of the Jwalamukhi Thrust, India: Tectonics
Dey, S., Thiede, R.C., Schildgen, T., Wittmann, H., Bookhagen, B., Scherler, D., and Strecker, M.
(Siehe online unter https://doi.org/10.1002/2015TC004002) - (2017). Sustained outof-sequence shortening along a tectonically active segment of the Main Boundary thrust: The Dhauladhar Range in the northwestern Himalaya. Lithosphere, 9(5), pp.715-725
Thiede, R.C., Robert, X., Stübner, K., Dey, S. and Faruhn, J.
(Siehe online unter https://doi.org/10.1130/L630.1) - (2018). Fault activity, tectonic segmentation, and deformation pattern of the western Himalaya on Ma timescales inferred from landscape morphology. Lithosphere, 10(5), pp.632-640
Nennewitz, M., Thiede, R.C. and Bookhagen, B.
(Siehe online unter https://doi.org/10.1130/L681.1) - (2018). Segmentation of the Main Himalayan Thrust Revealed by Low‐Temperature Thermochronometry in the Western Indian Himalaya. Tectonics, 37(8), pp.2710-2726
Eugster, P., Thiede, R.C., Scherler, D.,Stübner, K., Sobel, E., and Strecker, M.R.
(Siehe online unter https://doi.org/10.1029/2017TC004752)
