Spatial variability of source composition and petrogenesis in rift and rift flank alkaline lavas from the Eger Rift, Central Europe

Journal article
(Original article)


Publication Details

Author(s): Haase K, Beier C, Regelous M, Rapprich V, Renno A
Journal: Chemical Geology
Publisher: Elsevier B.V.
Publication year: 2016
ISSN: 0009-2541
Language: English


Abstract


Geochemical data on Oligocene melilititic and nephelinitic rocks from the northern Eger Rift flank in Central Europe reveal significant differences to nephelinites and basanites of volcanic complexes in the rift axis. The mafic rift flank lavas are more enriched in TiO, PO and CaO but have lower SiO compared to the alkaline volcanic rocks in the Eger Rift. The differences in major element compositions imply (1) lower degrees of partial melting beneath the rift flank than beneath the rift axis evident from lower SiO and higher (Ce/Yb) ratios in the off-axis basalts and (2) different assemblages of fractional crystallization. The mafic rift flank magmas experienced crystal fractionation of olivine followed by clinopyroxene fractionation in contrast to early simultaneous olivine and clinopyroxene fractionation in the magmas below the rift basin. In addition, assimilation of continental crustal rocks is associated with crystal fractionation and changes the composition of the lavas. The rift axis lavas are enriched in Nb and Ba relative to La and have higher Sr and lower Nd isotope ratios than the rift flank magmas indicating different mantle sources. The melting zones beneath the rift axis and the rift flank region are separated although they are only some 20km apart and no melt exchange between the magma systems is observed. All magmas probably experienced mixing between a deep carbonatitic and a shallower low-degree silicate melt.



FAU Authors / FAU Editors

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik
Regelous, Marcel PD Dr.
Geozentrum Nordbayern


External institutions
Technische Universität Bergakademie Freiberg


How to cite

APA:
Haase, K., Beier, C., Regelous, M., Rapprich, V., & Renno, A. (2016). Spatial variability of source composition and petrogenesis in rift and rift flank alkaline lavas from the Eger Rift, Central Europe. Chemical Geology. https://dx.doi.org/10.1016/j.chemgeo.2016.11.003

MLA:
Haase, Karsten, et al. "Spatial variability of source composition and petrogenesis in rift and rift flank alkaline lavas from the Eger Rift, Central Europe." Chemical Geology (2016).

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Last updated on 2018-08-08 at 05:15