The state of Meghalaya in NE India is a vibrant landscape where peoples livelihoods are intimately tied to the regional geology and seasonal climate. The climate of Meghalaya is defined by the Indian Summer Monsoon (ISM), which brings immense rainfall during the summer months. Uplift of the Shillong Massif, which dominates the topography of Meghalaya and contributes to orographic ISM precipitation in this region, is associated with historic mega earthquakes. However the long-term seismic history of the region is not well understood. Caves on the southern edge of the Massif, including Mawmluh Cave, provide unique opportunities to both improve understanding of the seismic history of NE India through uranium-thorium (U-Th) dating of tectonically broken speleothems and to study relationships between the ISM and other global climate indices through δ18O analysis of annually laminated speleothems. U-Th dating indicates that new speleothem growth on top of large broken speleothems in Mawmluh Cave initiated within 7 ± 2.2 years following the magnitude 8.7 1950 Assam-Tibet earthquake. These results suggest that dating of older breakdown structures could provide a stronger record of the seismic history of this region. Furthermore, a high-resolution modern speleothem δ18O record from Mawmluh Cave reveals ISM strength and frequency variations correlated with known changes in behavior of the El Niño Southern Oscillation over the past ~60 years, providing a new understanding of the influences on precipitation in NE India and a valuable calibration dataset for long-term speleothem paleoclimate records from this region.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07182014-122440 |
| Date | 22 July 2014 |
| Creators | Myers, Christopher Glen |
| Contributors | Steven L. Goodbred Jr., Jessica L. Oster, Larissa R.G. DeSantis |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07182014-122440/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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