000020393 001__ 20393
000020393 041__ $$aEnglish
000020393 100__ $$aTshering, P.
000020393 245__ $$aDetrital muscovite thermochronology in two drainage basins in western Bhutan
000020393 260__ $$c2007
000020393 260__ $$bMassachusetts Institute of Technology
000020393 260__ $$aCambridge, Massachusetts
000020393 502__ $$aThesis (S. M.) - Massachusetts Institute of Technology, Cambridge, Massachusetts 
000020393 520__ $$aNew reconnaissance data for a poorly characterized area in the western Bhutan Himalaya show distinction between the 40Ar/39Ar cooling age distributions of detrital minerals in the two river catchments of the Punatsang chu and the Wang chu. Muscovites from five samples of Wang chu river sands yield ages (corresponding roughly to the time of bedrock cooling through a temperature of ca.350°C) between 9.37± 0.08 Ma and 13.98 ± 0.08 Ma. The majority of ages are less than 13 Ma, and the data for all samples have a unimodal distribution with an average age of ca. 11.4 ± 1.5 Ma. In contrast, muscovites from 14 Punatsang chu samples yield ages with nearly the same total range but with a distinctively multi-modal distribution. Two modes predominate in the Punatsang chu data: one at ca. 11.4 Ma, which is statistically indistinguishable from the single mode of the Wang chu data, and one at ca. 14.5 Ma. The full explanation for this distribution must await further bedrock and detrital dating studies, but one hypothesis is that the out-of-sequence Kakhtang thrust fault system - which is thought to transect the upper reaches of the river catchments - has juxtaposed two bedrock terrains with different cooling histories.
000020393 653__ $$aPlanetary sciences
000020393 653__ $$aAtmospheric science
000020393 653__ $$aEarth Observation
000020393 650__ $$aEarth observation
000020393 8564_ $$uhttp://dspace.mit.edu/handle/1721.1/39008$$yExternal link
000020393 980__ $$aTHESIS