Oligocene, Permian and Panafrican zircon ages from rocks of the Balmuccia Peridotite and of the Lower Layered Group in the Ivrea Zone

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Authors:Gebauer, D.; Schmid, R.; von Quadt, A.; Ulmer, P.
Author Affiliations:Primary:
ETH-Zent., Swiss Federal Inst. Technology, Dep. Earth Sci., Zurich, Switzerland
Volume Title:Schweizerische Mineralogische und Petrographische Mitteilungen Bulletin Suisse de Minéralogie et Pétrographie
Source:Schweizerische Mineralogische und Petrographische Mitteilungen = Bulletin Suisse de Minéralogie et Pétrographie, 72(1), p.113-122. Publisher: Stäubli Verlag AG, Zurich, Switzerland. ISSN: 0036-7699
Publication Date:1992
Note:In English; 2 tables, anals.
Summary:U-Pb dating (SHRIMP) of magmatic zircons from a meta-gabbrodiorite dike within the Balmuccia peridotite yields an Oligocene age (31.1±1.5 Ma). Similarly, a meta-gabbrodiorite within the Lower Layered Group (LLG), adjacent to the Balmuccia periodite, yields an age of 26.0±0.8 Ma. Based on petrological data and microstructural observations both rocks must have been emplaced into, and equilibrated within, deep crustal levels. Sm-Nd wholerock data of these two rocks plont on the 600 Ma isochron of PIN and SILLS (1986) established for similar rocks of the LLG. This isochron must thus be reinterpreted as an inherited mantle mixing line possibly resulting from Panafrican mantle melting. The initial εNd-values of +7.7 and +11.1 as well as the geochemical data suggest a heterogeneous depleted mantle source for the two gabbroic rocks, possibly created by ESE subduction of Mesozoic oceanic crust (Valais Trough?).
Subjects:Absolute age; African Plate; Cenozoic; Dates; Electron probe data; Gabbros; Igneous rocks; Ion probe data; Mantle; Mass spectra; Metadiorite; Metaigneous rocks; Metamorphic rocks; Models; Nesosilicates; Oligocene; Orthosilicates; P-T conditions; Paleogene; Paleozoic; Pan-African Orogeny; Partial melting; Peridotites; Permian; Plate tectonics; Plutonic rocks; Precambrian; Proterozoic; SHRIMP data; Silicates; Sm/Nd; Spectra; Tertiary; U/Pb; Ultramafics; Upper Precambrian; Whole rock; Zircon; Zircon group; Alps; Europe; Italy; Ivrea-Verbano Zone; Southern Europe; Balmuccia Peridotite; Lower Layered Group
Abstract Numbers:93M/17
Record ID:1998009598
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique, Vandoeuvre-les-Nancy, France
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