Textural evidence of mafic-feslic magma interaction in dacite lavas, Clear Lake, California
- Queen's Univ., Kingston, Ontario (Canada)
At Clear Lake, California, the episode of volcanism from 0.65 to 0.30 Ma culminated in production of mixed dacite and rhyodacite lavas with bimodal phenocryst populations exhibiting extreme disequilibrium textures. These lavas formed by the interaction of subequal fractions of mafic recharge magma with the crystal-rich remnants of earlier-formed felsic magma bodies. The blending of basaltic andesite and rhyolite magmas dominated the early stages of mafic-felsic magma interactions. Partial quenching and segmentation of the resulting hybrid magma eventually led to the formation of quenched andesitic inclusions. During later stages of interaction, quenched inclusions suffered extensive disaggregation, contributing crystalline debris and residual silicic liquid to mixed dacites. The large range in mineral compositions and textures imply that given sufficient mafic input, preeruptive mixing is a remarkably efficient process, even in silicic magmas.
- OSTI ID:
- 7159414
- Journal Information:
- American Mineralogist; (United States), Journal Name: American Mineralogist; (United States) Vol. 77:7-8; ISSN AMMIAY; ISSN 0003-004X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
CALIFORNIA
CHEMICAL COMPOSITION
CHEMISTRY
CRYSTALLIZATION
CRYSTALLOGRAPHY
DEVELOPED COUNTRIES
GEOCHEMISTRY
GEOLOGY
IGNEOUS ROCKS
INCLUSIONS
LAVA
MAGMA
MINERALOGY
MIXING
NORTH AMERICA
PETROCHEMISTRY
PETROGENESIS
PETROLOGY
PHASE TRANSFORMATIONS
ROCKS
TEXTURE
USA
VOLCANIC ROCKS