Authors(s): Deepa Arya1, Gunjan Arya1, 2, R.B. Ananth3
Date of Publication: September, 2025
Publication reference: J. Ind. Geophys. Union, 29(5) (2025), 339-353
Abstract:
The Lansdowne klippe in the Lesser Himalaya is a thrust-plunging syncline comprising Precambrian granite and granite gneiss, prominently exposed around Jaiharikhal-Lansdowne in Garhwal region. The study area consists metasedimentary rocks, quartzose-phyllite, mylonite/phyllonite, granitic and augen gneisses. Granites exhibit medium-coarse, hypidiomorphic, and porphyritic textures with minerals Pl-Kfs-Qtz-Bt-Mus-Tour-Mag-Ap-Zr-Ep. Granite gneisses exhibit a mineral composition similar to that of granite, but with a well-developed foliation plane. Near fault zones, mylonitic textures with quartz ribbons and sericite occurrences, indicate NW-SE shearing. Textural features (porphyritic, perthitic) and geochemical characteristics (alkalic-ferroan, peraluminous), suggest slow cooling from a direct magmatic origin within syn-collisional to post-orogenic settings.
Keywords: Garhwal Himalaya, Lansdowne-Jaiharikhal granite and granite gneiss, Lansdowne klippe, Mineral chemistry, Geochemistry, Syn-collisional.