皇冠体育app petrology and geochemistry of Nevados de Chillan volcano, Chile. (Report No. WC/95/006)
Abstract
This report describes the petrology and geochemistry of the active volcano of Nevados de Chill谩n, which is situated at 36掳 50'S in the Southern Volcanic Zone of the Chilean Andes.
皇冠体育app study has been carded out at the University of Bristol as part of a broader assessment of the volcanic hazards of Nevados de Chill谩n, which is being undertaken in collaboration with the Servicio Nacional de Geolog铆a y Miner铆a of Chile, the British Geological Survey and the University of Lancaster. 皇冠体育app Nevados de Chill谩n hazard assessment in turn forms part of a wider ranging project entitled Volcanic Hazard Mapping for Development Planning (R5563), which is funded by the Emergency Aid Department of the Overseas Development Administration (ODA). It is led and co-ordinated by the British Geological Survey under the ODA/BGS Technology Development and Research Programme as part of the British Government's provision of aid through technical assistance to the developing countries.
皇冠体育app objective of the Nevados de Chill谩n project is to undertake a volcanic hazard assessment of the volcano using both conventional and experimental mapping techniques, with a view to developing and evaluating methods for the rapid mapping of volcanic hazards and production of hazard zone maps for use by planners and related agencies in developing countries.
A first phase of field survey work was undertaken on Nevados de Chill谩n in February and March 1994, and a second and final phase is being carried out at present. Following the first phase of fieldwork a number of questions arose concerning the stratigraphy and evolution of the volcano, and in particular the relationships between various lava groups that have been erupted from different volcanic centres on the Nevados de Chill谩n complex.
皇冠体育app evaluation of volcanic hazards requires a knowledge and understanding of the structure and geological evolution of a volcanic centre. 皇冠体育app petrological and geochemical study described in this report was undertaken to help elucidate the problems related to lava classification and stratigraphy at Nevados de Chill谩n, and also to gain an insight into the nature of the magmatic processes operating within and beneath the volcano. 皇冠体育app investigation was carried out in close collaboration with other members of the project team who are concerned primarily with the geological mapping and hazard assessment. Through an iterative process drawing upon the petrological and geochemical data, as well as photogeological interpretations and field observations, it has been possible to refine the stratigraphy and geological map of the volcano. This has resulted in a better understanding of the evolution and eruptive history of the volcano as a whole, which will ultimately be reflected in a more realistic assessment of the nature, distribution and impact of potential hazards on the surrounding region.
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