The plutonic crust of Kohistan and volcanic crust of Kohistan–Ladakh, north Pakistan/India: lessons learned for deep and shallow arc processes

<jats:title>Abstract</jats:title> <jats:p> The Kohistan–Ladakh terrane, northern Pakistan/India, offers a unique insight into whole-arc processes. This research review presents summaries of fundamental crustal genesis and evolution models. Earlier work focused on arc sequence definition. Later work focused on holistic petrogenesis. A new model emerges of an unusually thick ( <jats:italic>c.</jats:italic> 55 km) arc with a <jats:italic>c.</jats:italic> 30 km-thick batholith. Volatile-rich, hornblende ± garnet ± sediment assimilation-controlled magmatism is predominant. The thick batholith has a complementary mafic–ultramafic residue. Kohistan crustal SiO <jats:sub>2</jats:sub> contents are estimated at >56%. The new-Kohistan, silicic-crust model contrasts with previous lower SiO <jats:sub>2</jats:sub> estimates ( <jats:italic>c.</jats:italic> 51% SiO <jats:sub>2</jats:sub> crust) and modern arcs that imply <35 km crustal thicknesses and arc batholith thicknesses of <jats:italic>c.</jats:italic> 7 km. A synthetic overview of Kohistan–Ladakh volcanic rocks presents a model of an older, cleaved/deformed Cretaceous volcanic system at least 800 km across strike. The Jaglot–Chalt–Dras–Shyok volcanics exhibit predominant tholeiitic-calc-alkaline signatures, with a range of arc-related facies/tectonic settings. A younger, post-collisional, Tertiary silicic volcanic system (the Shamran–Dir–Dras-2–Khardung volcanics) lie unconformably upon Cretaceous basement, and erupted within an intra-continental tectonic setting. Kohistan–Ladakh tectonic model controversies remain. In essence, isotope-focused researchers prefer later (Tertiary) collisions, whilst structural field-geology-orientated researchers prefer an older (Cretaceous) age for the Northern/Shyok Suture. </jats:p>