Universität zu Köln

Schneider, K. P., Kirchenbaur, M., Fonseca, R. O. C., Kasper, H. U., Muenker, C. and Froitzheim, N. (2016). Role of crustal assimilation and basement compositions in the petrogenesis of differentiated intraplate volcanic rocks: a case study from the Siebengebirge Volcanic Field, Germany. Contrib. Mineral. Petrol., 171 (6). NEW YORK: SPRINGER. ISSN 1432-0967

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Abstract

The Siebengebirge Volcanic Field (SVF) in western Germany is part of the Cenozoic Central European Volcanic Province. Amongst these volcanic fields, the relatively small SVF comprises the entire range from silica-undersaturated mafic lavas to both silica-undersaturated and silica-saturated differentiated lavas. Owing to this circumstance, the SVF represents a valuable study area representative of intraplate volcanism in Europe. Compositions of the felsic lavas can shed some new light on differentiation of intraplate magmas and on the extent and composition of potential crustal assimilation processes. In this study, we provide detailed petrographic and geochemical data for various differentiated SVF lavas, including major and trace element concentrations as well as Sr-Nd-Hf-Pb isotope compositions. Samples include tephriphonolites, latites, and trachytes with SiO2 contents ranging between 53 and 66 wt%. If compared to previously published compositions of mafic SVF lavas, relatively unradiogenic Nd-143/Nd-144 and Hf-176/Hf-177 coupled with radiogenic Sr-87/Sr-86 and Pb-207/Pb-204 lead to the interpretation that the differentiated volcanic rocks have assimilated significant amounts of lower crustal mafic granulites like the ones found as xenoliths in the nearby Eifel volcanic field. These crustal contaminants should possess unradiogenic Nd-143/Nd-144 and Hf-176/Hf-177, radiogenic Sr-87/Sr-86, and highly radiogenic Pb-207/Pb-204 compositions requiring the presence of ancient components in the central European lower crust that are not sampled on the surface. Using energy-constrained assimilation-fractional crystallisation (EC-AFC) model calculations, differentiation of the SVF lithologies can be modelled by approximately 39-47 % fractional crystallisation and 6-15 % crustal assimilation. Notably, the transition from silica-undersaturated to silica-saturated compositions of many felsic lavas in the SVF that is difficult to account for in closed-system models is also well explained by such amounts of crustal assimilation.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schneider, K. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kirchenbaur, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fonseca, R. O. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kasper, H. U. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muenker, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Froitzheim, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-273127
DOI:	10.1007/s00410-016-1271-7
Journal or Publication Title:	Contrib. Mineral. Petrol.
Volume:	171
Number:	6
Date:	2016
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-0967
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LOWER CONTINENTAL-CRUST; TRACE-ELEMENT; ISOTOPIC COMPOSITIONS; LITHOSPHERIC MANTLE; ALKALINE MAGMATISM; WEHR VOLCANO; LU-HF; TERTIARY; ND; PB Multiple languages Geochemistry & Geophysics; Mineralogy Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27312