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Rates of landscape development in the Transhimalaya of northern India: a framework for testing the links among climate, erosion, and tectonics

Dortch, Jason Michael

Abstract Details

2010, PhD, University of Cincinnati, Arts and Sciences : Geology.

Models linking Earth’s surficial (exogenic) processes and internal processes (endogenetic) have been evolved recently, specifically involving the role of glaciation and fluvial incision in unloading rock mass and inducing surface uplift, and the influence of glacial, fluvial, and mass wasting systems in limiting and/or creating topography. However, these models are poorly defined due to a lack of quantified studies of the rates and magnitudes of geomorphic processes that control erosion and landscape development. Furthermore, the regional variability of erosive processes and the role of high magnitude-low frequency processes in landscape development are poorly defined. A key area of the Himalaya-Tibetan orogen, northern Ladakh was therefore examined using field mapping, satellite remote sensing and terrestrial cosmogenic nuclide (TCN) methods to quantify the relative role of these processes and to provide a framework to test the newly developing geologic models. The new data allows linkages between climatic change, long-term temporal variation in the rates of geomorphic processes, and catastrophic events are assessed.

Study of glaciation shows in Ladakh shows showed that glaciations was approximately twice as extensive on the northern side of the Ladakh Range during the same glaciation, which would implies that that erosion should be greater on the northern slopes of the range. To test this assumption, TCN basin wide erosion methods that integrate long-term erosion were undertaken and show that catchments on the southern side of the range erode at ~0.025 mm/yr while three catchments on the northern side erode at ~0.050 m mm/yr. This suggests that erosion rates are dominantly controlled by glaciation.

Seventeen strath terraces in the Himalaya and Transhimalaya were dated using TCN methods to test the temporal variations in the rates of incision. These data were combined with previous studies that show that Holocene fluvial incision rates range from ~0.02 mm/yr to ~26 mm/yr, while Pleistocene fluvial incision rates ≤ 5 mm/yr. This argues that fluvial incision is more important than glacial erosion in shaping landscapes in Ladakh.

Examination and dating of large landslides and catastrophic flood deposits show that there are strong temporal controls on these events, coincident with times of increase rainfall when the monsoon was enhanced.

Climatic records show that the Holocene (0-10 ka) is a generally wet period and that 10-35 ka is generally more arid. Three of the four large landslides occurred during enhanced monsoon phase-2 (~8 ka). This new data, combined with a regional summary of all large and giant landslides dated in the Himalayan-Tibetan Orogen (n=12) shows a strong correlation between sliding occurrence and intensified monsoon precipitation.

These data show that temporal variations in incision rates and landslide occurance are strongly coupled with significant fluctuations in precipitation due to intensified monsoons throughout the Quaternary.

Lewis Owen, PhD (Committee Chair)
Craig Dietsch, PhD (Committee Member)
Marc Caffee, PhD (Committee Member)
Lindsay Schoenbohm, PhD (Committee Member)
David Byer Nash, PhD (Committee Member)
399 p.

Recommended Citations

Citations

  • Dortch, J. M. (2010). Rates of landscape development in the Transhimalaya of northern India: a framework for testing the links among climate, erosion, and tectonics [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275916201

    APA Style (7th edition)

  • Dortch, Jason. Rates of landscape development in the Transhimalaya of northern India: a framework for testing the links among climate, erosion, and tectonics. 2010. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275916201.

    MLA Style (8th edition)

  • Dortch, Jason. "Rates of landscape development in the Transhimalaya of northern India: a framework for testing the links among climate, erosion, and tectonics." Doctoral dissertation, University of Cincinnati, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275916201

    Chicago Manual of Style (17th edition)