Holocene monsoonal dynamics and fluvial terrace formation in the northwest Himalaya, India
- 1Institut für Geowissenschaften, Universität Potsdam, 14415 Potsdam, Germany
- 2Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA
- 3Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
- 4Institut für Geowissenschaften, Universität Potsdam, 14415 Potsdam, Germany
Abstract
Aluminum-26 and beryllium-10 surface exposure dating on cut-and-fill river-terrace surfaces from the lower Sutlej Valley (northwest Himalaya) documents the close link between Indian Summer Monsoon (ISM) oscillations and intervals of enhanced fluvial incision. During the early Holocene ISM optimum, precipitation was enhanced and reached far into the internal parts of the orogen. The amplified sediment flux from these usually dry but glaciated areas caused alluviation of downstream valleys up to 120 m above present grade at ca. 9.9 k.y. B.P. Terrace formation (i.e., incision) in the coarse deposits occurred during century-long weak ISM phases that resulted in reduced moisture availability and most likely in lower sediment flux. Here, we suggest that the lower sediment flux during weak ISM phases allowed rivers to incise episodically into the alluvial fill.
Footnotes
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↵*bodo{at}crustal.ucsb.edu; Current address: Institute for Crustal Studies, University of California–Santa Barbara, Santa Barbara, California 93106, USA
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- Accepted 28 February 2006.
- Received 8 February 2006.
- Revision received 23 February 2006.
- The Geological Society of America, Inc.
