Petrology of Lingtse Granite of Linkey-Barapathing Stretch of East Sikkim in the Light of Geostatistical, Chemical and Experimental Studies

The Dalmg Group of rocks ot Darjeehng-Sikkim Himalaya is often traversed by Lingtse granite occurring as thrust sheets In the piesent contnbuhon, a cohesive petrogenetic model of the Lingtse granite (in Linkey Barapathing stietch of East Sikkim) has been proposed based on critical evaluation of its mode of occurrence, petrographic analyses, chemistry and one-atmosphere experimental studies The investigated Lingtse granite, m general, maintains a very close spatial association with the adjoining schistose country rocks and the planar elements like schistosity and crenulation cleavage are found to be continuous from the country rocks to the Lmgtse granites The poor t orrelation amongst several mineralogical parameters is suggestive of open system melt-rock interation A closei scan of several chemical variation diagiams for the investigated Lingtse granites reveals a wide scatter of the data-plots which may be indicative ot metasomatism/hybridization and other processes related to open system Interestingly, presence of nebeckite in Lingtse granite is experimentally verified to be the product of alkali (soda) - silica metasomatism of the chlonte-biotite muscovite schist country rock The A type characteristics of Lmgtse granite is suggestive of syn-or-post collisional tectonic setting of the host terrain.