The Himalayan Orogen is one of the classic example of continent-continent collision (e.g., Argand, 1924; Dewey & Bird, 1970; Molnar & Tapponnier, 1975; Tapponnier & Molnar, 1976), characterised by a high convergence rate of 5 cm.yr-1 currently ongoing (Patriat & Achache, 1984; Klootwijk et al., 1992). The NW part of the orogen (NW Syntaxis) is made up of terranes formed during the intra-oceanic (Tethyan) stages of the India-Asia convergence (Ladakh and Kohistan terranes), as well as terranes largely deformed and metamorphosed during the Himalayan orogeny (Karakoram and Indian margins). For this reason, the NW Syntaxis is a key area to reconstruct the various steps of convergence of the Indian and Asian continents, since about 120 Ma.

In this paper, after a brief summary of observations and bibliography on the pre-Himalayan history of the NW Himalaya, followed by a review of our present understanding of the India-Asia convergence in NW Himalaya, we propose a tectonic reconstruction of India-Asia convergence for that part of the chain. This reconstruction is based on the compilation of structural, geochemical and metamorphic data from the area. The intra-oceanic phase of convergence is deduced mainly from the petro-geochemistry of the arc lavas (Rolland et al., 2000; 2002a); while the post-collisional phase is constrained by structural, metamorphic, magmatic and chronological data (Rolland, 2000; Rolland & Pêcher, 2001; Rolland et al., 2001, accepted; Mahéo et al., 2002).