Universität zu Köln

Brandl, Philipp A., Genske, Felix S., Beier, Christoph ORCID: 0000-0001-7014-7049, Haase, Karsten M., Sprung, Peter ORCID: 0000-0003-4862-1415 and Krumm, Stefan H. (2015). Magmatic Evidence for Carbonate Metasomatism in the Lithospheric Mantle underneath the Ohre (Eger) Rift. J. Petrol., 56 (9). S. 1743 - 1775. OXFORD: OXFORD UNIV PRESS. ISSN 1460-2415

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Abstract

Magmas erupted in intracontinental rifts typically form from melting of variable proportions of asthenospheric or lithospheric mantle sources and ascend through thick continental lithosphere. This ascent of magma is accompanied by differentiation and assimilation processes. Understanding the composition of rift-related intracontinental volcanism is important, particularly in densely populated active rift zones such as the Ohre (Eger) Rift in Central Europe. We have sampled and analysed nephelinites from Zelezna hurka (Eisenbuhl), the youngest (<300 ka) Quaternary volcano related to the Ohre Rift where frequent earthquake swarms indicate continuing magmatic activity in the crust. This nephelinite volcano is part of a larger eruptive centre (Mytina Maar) representing a single locality of recurrent volcanism in the Ohre Rift. We present a detailed petrographic, mineralogical and geochemical study (major and trace elements and Sr-Nd-Hf-O isotopes) of Zelezna' hurka to further resolve the magmatic history and mantle source of the erupted melt. We find evidence for a highly complex evolution of the nephelinitic melts during their ascent to the surface. Most importantly, mixing of melts derived from different sources and of strong chemical contrast controls the composition of the erupted volcanic products. These diverse parental melts originate from a highly metasomatized subcontinental lithospheric mantle (SCLM) source. We use a combined approach based on mineral, glass and whole-rock compositions to show that the mantle underneath the western Ohre Rift is metasomatized dominantly by carbonatitic melts. The nephelinites of Zelezna hurka formed by interaction between a carbonatitic melt and residual mantle peridotite, partial crystallization in the lithospheric mantle and minor assimilation of upper continental crust. Thermobarometric estimates indicate that the stagnation levels of the youngest volcanism in this part of the Ohre Rift were deeper than the focal depths of recent earthquake swarms, indicating that those are not directly linked to magma ascent. Furthermore, close mineralogical and geochemical similarities between the Zelezna 'hurka nephelinite and fresh kimberlites may point towards a genetic link between kimberlites, melilitites and nephelinites.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Brandl, Philipp A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Genske, Felix S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Beier, Christoph UNSPECIFIED orcid.org/0000-0001-7014-7049 UNSPECIFIED Haase, Karsten M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sprung, Peter UNSPECIFIED orcid.org/0000-0003-4862-1415 UNSPECIFIED Krumm, Stefan H. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-393660
DOI:	10.1093/petrology/egv052
Journal or Publication Title:	J. Petrol.
Volume:	56
Number:	9
Page Range:	S. 1743 - 1775
Date:	2015
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1460-2415
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language UDACHNAYA-EAST KIMBERLITE; GREEN-CORE CLINOPYROXENES; TRACE-ELEMENT; CENTRAL-EUROPE; PERIDOTITE XENOLITHS; VOLCANIC PROVINCE; BOHEMIAN MASSIF; LU-HF; OLIVINE MELILITITES; ALKALINE MAGMATISM Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/39366