Petrographic and Geochemical Analyses of Mafic Enclaves from Uturuncu Volcano, SW Bolivia
Abstract
Magma mixing is an essential concept in igneous petrology used to classify volcanic systems. Evidence of magma mixing includes magmatic enclaves, which are inclusions emplaced within a host magma of related but distinct composition and of separated genesis. Enclaves are pertinent to our understanding of volcanic systems, as they provide information about the internal processes involved within the magma chamber. The origin of these features is uncertain and a variety of hypotheses exist, including: incorporation of solid wall rock, xenoliths, restite retained from deep crustal melting zones, and cumulate fragments derived from the partially crystalline rinds of upper crustal magma reservoirs. We characterized mafic enclaves within lava flows from Uturuncu Volcano in Southwest Bolivia to determine heterogeneity and evolution of the system and the origin of the enclaves. Methods used were X-ray fluorescence (XRF) and petrographic analyses of thin sections. These analyses were conducted on fifteen samples collected from a variety of lava flows. We present here petrographic and geochemical heterogeneity within mafic enclaves from a single flow and other flows that span the lifespan of Uturuncu volcano. We propose the enclaves originated as undercooled blobs from a deeper crustal reservoir that were not completely mixed with the host melt.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.V43B2574A
- Keywords:
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- 1065 GEOCHEMISTRY / Major and trace element geochemistry;
- 3625 MINERALOGY AND PETROLOGY / Petrography;
- microstructures;
- and textures