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The Shyok Suture Zone is an oceanic remnant of the Neo-Tethyan ocean sandwiched between the Ladakh Batholiths to the south and Karakoram Batholith to the north. The Tirit granitoids in this suture are dark-coloured, relatively rich in ferromagnesian minerals and range from granodiorite-tonalite to gabbro-diorite in composition. Mafic igneous enclaves are quite common and they are intruded by NW-SE parallel doleritic and aplitic dykes. The Tirit granitoids have a wide range of major oxide compositions (SiO2 = 52.1-72.11 wt %, TiO2 = 0.21-1.23 wt %, Al2O3 = 11.42-13.52 wt %, MgO = 1.69-10.69 wt % and CaO = 3.24-9.31 wt %) and show calc-alkaline, metaluminous, I-type characteristics, transitional between primitive and mature arc continental plutons. Rare earth elements (REE) show considerable enrichment in light REE (LREE) as compared to the heavy REE (HREE). Late Cretaceous U/Pb dates (74-68 Ma) show that they formed during the pre-collision northward movement of India. The Tirit dykes are only slightly younger and probably part of the same episode.

The Tirit granitoids exposed along the Nubra–Shyok river valleys in northern Ladakh, constitute an important tectonic unit of the Shyok suture zone. They are weakly deformed medium- to coarse-grained, subleucocratic to mesocratic, and compositionally range from granodiorite-tonalite to gabbrodiorite. They are syncollisional, calc-alkaline and volcanic-arc related granitoids. In several places, these granitoids have been intruded by post-collisional doleritic and aplitic dykes. In order to constrain the geological history of the Nubra-Shyok valleys, the crystallization age of zircons from one granodioritic sample of the Tirit granitoids was determined. The new U–Pb zircon age data point to a 71.40 ± 0.36 Ma crystallization age for the Tirit granitoids, which is in close agreement with the previous age estimates of 73.6–68 Ma. This suggests that the collision and suturing of the Shyok marginal basin with the Karakoram block (southern Asian margin) have occurred before 72 Ma and subduction-related major plutonism along the Shyok suture persisted till 68 Ma. However, the collision and suturing of the Indian and Asian plates took place along the Indus suture at 60–50 Ma.