Structural evolution of the Lopukangri rift, south-central Tibet: Implications for intercontinental deformation, timing of extension of the Tibetan plateau, and evolution of the Himalaya orogen and India-Asia suture zone

Suture zones are often the locus of deformation throughout intercontinental collision. This poses a challenge in developing models of their evolution. The India-Asia suture zone has been a site of continuous deformation for the past ∼55 Ma. Regionally, four crustal structures have been interpreted to play major roles in modifying the suture zone: 1) the Gangdese thrust, 2) the Ayi Shan detachment, 3) the Great Counter thrust, and 4) extensional systems of the Tibetan Plateau. Only some of these have been identified and documented in detail. My research exploits the Lopukangri area which archives products of the deformation associated with each of these structures. Several tectonic units are well-exposed here, including Indian passive margin rocks (Tethyan Sedimentary Sequence), forearc deposits (Xigaze Group), magmatic arc rocks (Gangdese batholith and Linzizong Formation) and syncollision deposits (Tertiary conglomerates). To assess the evolution of the India-Asia suture zone, I integrate field mapping, remote sensing analyses and U-Pb zircon geochronology and 40Ar/39Ar biotite and muscovite thermochronology.