Our clients include people from all walks of life and they ask us all kinds of questions which we are usually happy to answer. But rock formations and geology can be tough one sometimes!
We were happy to discover, however, that Christopher Spencer, part of a group of geologists who went rafting with Rimo Expeditions on the Zanskar River a few years ago put together a very helpful blog post at http://www.travelinggeologist.com
So next time someone asks us what rock formation that is or what to expect on one of our treks or expeditions – as far as geology goes – we can say stuff like this:
Our journey to Ladakh will traverse a cross section of a classic volcanic arc complex. Beginning with the Indus suture zone and the Ladakh oceanic arc proceeding through the Shyok suture zone and all its ophiolite goodness to the Karakorum continental arc. This transect covers nearly 100 million years of subduction magmatism and accretion and over 50 million years of continent-continent collision …
… The Ladakh batholith is characterised by coarse-grained granite and granodiorite with abundant diorite enclaves concentrated at the margins and nearly absent towards its core. In the core of the batholith, large potassium feldspar dominate the mineralogy. The main part of the Ladakh batholith comprises the Late Cretaceous-Eocene (102-50 Ma) granitoids which is bounded on its southern and northern margin by the Indus Group and the Shyok suture zone, respectively …
…Across the Karakorum fault is the Shyok suture zone (my favorite part of the trip). The Shyok suture zone is a thick mélange considered by many to be a remnant of a Cretaceous back-arc basin separating the Ladakh island arc from the Karakoram continental arc and thus the Asian margin. The suture zone is primarily an ophiolite mélange, with mafic volcanics and minor amounts of sediments incorporated in the mix. Within the Shyok suture zone we find many of the classic parts of a supra-subduction ophiolite complex with exception of the sheeted dikes and layered gabbros. However, like many ophiolite complexes the lack of these components might imply either that they did not form as part of the oceanic lithosphere or that were removed during tectonic erosion during continued subduction and collision, which appears to be the case in the Shyok suture zone.
Thank you for the great post!
For the full blog post, please click here.
Some more photos from their blog: