Publication Date:
2017-04-04
Description:
The origin of bimodal (mafic–felsic) rock suites is a fundamental question in volcanology.
Here we use major and trace elements, high-resolution Sr, Nd and Pb isotope analyses, experimental petrology and thermodynamic modelling to investigate bimodal magmatism at the iconic Carlingford Igneous Centre, Ireland. We show that early microgranites are the result of extensive assimilation of trace element-enriched partial melts of local metasiltstones
into mafic parent magmas. Melting experiments reveal the crust is very fusible, but thermodynamic modelling indicates repeated heating events rapidly lower its melt-production
capacity. Granite generation ceased once enriched partial melts could no longer form and subsequent magmatism incorporated less fertile restite compositions only, producing mafic intrusions and a pronounced compositional gap. Considering the frequency of bimodal magma suites in the North Atlantic Igneous Province, and the ubiquity of suitable crustal compositions, we propose ‘progressively inhibited crustal assimilation’ (PICA) as a major
cause of bimodality in continental volcanism.
Description:
Irish Research Council for
Science, Engineering and Technology (IRCSET)
Science Foundation Ireland basic research
Description:
Published
Description:
4199
Description:
1V. Storia e struttura dei sistemi vulcanici
Description:
JCR Journal
Description:
restricted
Keywords:
Bimodal magmatism
;
crustal contamination
;
isotope geochemistry
;
experimental petrology
;
04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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