Abstract
A high-resolution record of Indian summer monsoon variability preserved by speleothem carbonate mineralogy
Abstracts with programs - Geological Society of America, Vol.31(7), p.153
Geological Society of America, 1999 annual meeting
1999
Abstract
Stalagmites from Siddha Baba Guffa (28 degrees 15'N, 84 degrees 00'E; elevation approximately 1000 m), a well-ventilated, dolomitic cave in the Pokhara Valley, central Nepal, preserve a mineralogical record of Indian summer monsoon variability over the past 2300 years. Annually-deposited aragonite layers formed between 2300 and 1500 yr B.P. indicate reduced monsoon moisture and high cave aridity, while alternating calcite/aragonite laminae deposited after 1500 yr B.P. record increased summer monsoon moisture and a more humid cave atmosphere during the summer monsoon. The mechanism driving aragonite crystallization appears to be linked to inhibition of calcite precipitation by Mg-rich dripwater in an evaporative cave environment.The transition from aragonite-only layers to aragonite/calcite laminae at 1500+ or -20 (2 std dev) yr B.P. is abrupt and suggests that monsoon precipitation increased suddenly at this time. Dense, optically clear calcite from 450+ or -7 to 360+ or -20 yr B.P. (1550 to 1640 A.D.) and during two shorter intervals after 1640 A.D. indicate cool and/or moist conditions coincident with the Little Ice Age. The interval following approximately 1800 A.D. is predominantly aragonite and may mark warming at the end of the Little Ice Age. Similar changes in monsoon regime have been noted from regional continental records, but most are limited either in temporal resolution or geographic distribution. Karst is abundant throughout central Nepal, and thus speleothems may provide unique insight into short duration changes in the character of the Indian summer monsoon throughout the Holocene and late Pleistocene.
Details
- Title: Subtitle
- A high-resolution record of Indian summer monsoon variability preserved by speleothem carbonate mineralogy
- Creators
- Rhawn F Denniston - University of IowaLuis A GonzalezMark K ReaganYemane Asmerom
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.31(7), p.153
- Conference
- Geological Society of America, 1999 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1999 annual meeting
- Language
- English
- Date published
- 1999
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240806002771
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