Preliminary chemical and isotopic characterization of high-altitude spring waters from eastern Nepal Himalaya

Metamorphic degassing from active collisional orogens supplies a significant fraction of CO2 to the atmosphere, thus playing a fundamental role even in today's Earth carbon cycle. Appealing clues for a contemporary metamorphic CO2 production in active orogens are represented by the widespread occurrence, along the whole Himalayan belt, of CO2 rich hot-springs mainly localized along major tectonic discontinuities. In contrast to these well-studied hot-springs, almost no chemical and isotopic data are actually available for cold-springs, especially for those located at high-altitude and in remote areas of the Himalayas. In the framework of the Ev-K2-CNR SHARE (Stations at High Altitude for Research on the Environment) Project, we have started a preliminary chemical and isotopic study on high-altitude cold-springs located at different structural levels in the eastern Nepal Himalayas. Chemical and isotopic data obtained from the high-altitude cold-springs are compared with those obtained by previous authors from hot-springs located along the MCT. The isotopic signature of stable isotopes of hydrogen and oxygen could help to identify the waters sources in the investigated Himalayan sectors, to individuate mixing phenomena between waters of different provenience and possible connection with different circulation nets. These first measurements on high-altitude springs from remote areas of eastern Nepal represent a first step towards a better definition of a reliable scenario of water resources availability and will contribute to the understanding of the water cycle in the studied area.