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F-GEO-Naturvitenskap, geofag

U-Pb geochronology of Caledonian eclogites

Awarded: NOK 1.6 mill.

The project will investigate the timing of eclogite formation in the Western Gneiss Region and Seve Nappe Complex of the Scandinavian Caledonides and in North-East Greenland. The presently known chronology of the Western Gneiss Region shows that the high- pressure metamorphic events spanned some 20 million years between about 415 and 395 Ma. The causes and implications of these local differences are not well understood. The project will use high-resolution methods to better understand the reasons for these age variations and to construct realistic models for the terminal collisional processes between Laurentia and Baltica. The Seve Nappe Complex contains the record of older, Ordovician, continental subduction events at ca. 500 Ma and apparently again at 45 0 Ma, predating the amalgamation of the terrane to Baltica during the final Scandian events in the Devonian. The aim of the U-Pb work is to establish a more detailed geochronological data base using the robust mineral zircon to confirm or amend the presen t temporal framework. On that basis it will be possible to reexamine fundamental questions concerning the presumed origin of these terranes from the late-Precambrian continental rim of Baltica, the early collision and subduction history, and the relations hips to other allochthonous terranes within the sequence of nappes. On the technical side, the project aims at developing better and more efficient means for the determination of precise ages and their unambiguous link to particular stages in the evoluti on of high-pressure rocks. This will include field mapping, petrographic characterization by various methods and at various scales, and zircon selection and treatment procedures for the separation of specific growth phases and the elimination of secondary disturbances. The insertion of a well motivated post-doctoral student with previous experience will help to consolidate the technical level of the present U-Pb laboratory at the Department of Geology in Oslo.

Funding scheme:

F-GEO-Naturvitenskap, geofag

Thematic Areas and Topics

No thematic area or topic related to the project