[en] Nepal is localized in the central part of the Himalayan arc. In uplift since the Cenozoic time, the Himalaya is traditionally divided into six lithotectonic zones extending in parallel belts. From north to south there are respectively: (1) the Trans-Himalayan batholith; (2) the Indus-Tsangpo suture zone; (3) the Tethyan (Tibetan) Himalaya; (4) the Higher (Greater) Himalaya; (5) the Lesser Himalaya; and (6) the Sub-Himalaya.
This PhD thesis is focused on the Tethyan sedimentary rocks exposed in the Nepal Tethyan Himalaya belt and in the thrusting nappes belonging to the Lesser Himalaya. These nappes contain unmetamorphosed sedimentary rocks which might belong to the Tethyan sedimentary succession. The Tethyan Himalaya has preserved highly fossiliferous marine rocks deposited on the shelf and slope of the Indian continental margin from Late Proterozoic-Cambrian through early Eocene times.
The main objective of this PhD thesis is to build a first sedimentological canvas for the Lower Paleozoic and Devonian carbonated rocks of Nepal which could be compared with the Belgian facies. This long distance comparison between the Belgian and the Nepalese basins will allow to have a better understanding of the phenomena that run the global carbonate sedimentation. The methods that will be used to achieve this work are: (1) bed by bed sampling; (2) petrographic analysis and facies modelling; (3) magnetic susceptibility analysis for correlations and eustatism and (4) paleontological datation.
A first sedimentological campaign took place during the months of March and April 2009. It allowed to study three sections around Katmandu valley and two sections in the Annapurna range (Manang area). The sections studied around Katmandu (Pulchauki and Chandragiri Hill) belonged to the Formation of Chandragiri (Ordovician) and Godavari (Devonian) which are mainly constituted by carbonate rocks. The sections described in Manang area are mainly made-up by the terrigeneous rocks of the Dark Band, Tilicho Pass and Tilicho Lake Formation (Silurian to Lower Carboniferous).
The diversity of facies observed in these five sections will be exposed.
