TY - JOUR

T1 - Plagioclase transfer from a host granodiorite to mafic microgranular enclaves

T2 - diverse records of magma mixing

AU - Pietranik, Anna

AU - Koepke, Jurgen

N1 - Funding Information: J. Gruszczynska and A. Winiecka helped to locate representative samples of the Kośmin enclaves. Master thesis of J. Gruszczynska (Gruszczynska ) contributed to this manuscript. AP acknowledges grant no. N N307 105235 by the Polish Ministry of Science and Higher Education. Comments by Marco Viccaro and an anonymous reviewer and the editor Martin Okrusch are gratefully acknowledged.

PY - 2014/10

Y1 - 2014/10

N2 - Chemical and structural zoning in plagioclase can develop in response to a number of different magmatic processes. We examine plagioclase zonation formed during the transfer of plagioclase from a granodioritic host to a monzodioritic enclave to understand the development of different zonation patterns caused by this relatively simple magma mixing process. The transferred plagioclase records two stages of evolution: crystallization of oscillatory plagioclase in the host granodioritic magma and crystallization of high An zones and low An rims in the hybrid enclave magma. High An zones (up to An72) are formed only in the hybrid enclaves after plagioclase transfer. Plagioclase from a primitive enclave, showing no or only minimal interaction with the host, is An30–43. The implication is that high An zones crystallize only from the hybrid magma and not from the primitive one, probably because of an increase in water content in the hybrid magma. Complex interactions between the two magmas are also recorded in Sr content in plagioclase, which indicates an initial increase in Sr concentration in the melt upon transfer. This is contrary to what is expected from the mixing of low Sr enclave magma with a high Sr granodiorite one. Such Sr distribution in the plagioclase implies that the transfer of the plagioclase took place before the onset of plagioclase crystallization in the enclave magma. Therefore, the mixing between high Sr granodiorite magma and low Sr enclave magma was recorded only in plagioclase rims and not in the high An zones.

AB - Chemical and structural zoning in plagioclase can develop in response to a number of different magmatic processes. We examine plagioclase zonation formed during the transfer of plagioclase from a granodioritic host to a monzodioritic enclave to understand the development of different zonation patterns caused by this relatively simple magma mixing process. The transferred plagioclase records two stages of evolution: crystallization of oscillatory plagioclase in the host granodioritic magma and crystallization of high An zones and low An rims in the hybrid enclave magma. High An zones (up to An72) are formed only in the hybrid enclaves after plagioclase transfer. Plagioclase from a primitive enclave, showing no or only minimal interaction with the host, is An30–43. The implication is that high An zones crystallize only from the hybrid magma and not from the primitive one, probably because of an increase in water content in the hybrid magma. Complex interactions between the two magmas are also recorded in Sr content in plagioclase, which indicates an initial increase in Sr concentration in the melt upon transfer. This is contrary to what is expected from the mixing of low Sr enclave magma with a high Sr granodiorite one. Such Sr distribution in the plagioclase implies that the transfer of the plagioclase took place before the onset of plagioclase crystallization in the enclave magma. Therefore, the mixing between high Sr granodiorite magma and low Sr enclave magma was recorded only in plagioclase rims and not in the high An zones.

UR - http://www.scopus.com/inward/record.url?scp=84925380942&partnerID=8YFLogxK

U2 - 10.1007/s00710-014-0326-6

DO - 10.1007/s00710-014-0326-6

M3 - Article

AN - SCOPUS:84925380942

VL - 108

SP - 681

EP - 694

JO - Mineralogy and petrology

JF - Mineralogy and petrology

SN - 0930-0708

IS - 5

ER -