Recycling and recharge at Hasandag stratovolcano, Central Anatolia: insights from plagioclase textures and zoning patterns


Gall H., KÜRKCÜOĞLU B., Cipar J., Crispin K., Furman T.

CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, vol.177, no.8, 2022 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 177 Issue: 8
  • Publication Date: 2022
  • Doi Number: 10.1007/s00410-022-01949-y
  • Journal Name: CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, Aquatic Science & Fisheries Abstracts (ASFA), Artic & Antarctic Regions, Chemical Abstracts Core, Environment Index, Geobase
  • Keywords: Intermediate lavas, Magma mixing, Feldspar zoning, Mg diffusion in plagioclase, Hasandag volcano, Magma recharge, SOUFRIERE HILLS VOLCANO, CALC-ALKALINE, MT. ERCIYES, POSTCOLLISIONAL VOLCANISM, MAGMA STORAGE, DIFFUSION, COLLISION, EVOLUTION, ERUPTION, SR

Abstract

We explore crystal growth and magma recharge during the formation of intermediate lavas using bulk rock compositions and zoning patterns and textural variation in plagioclase feldspars from Hasandag volcano in south-central Turkey. Hasandag intermediate lavas formed primarily through fractionation of the observed mineral phases, and also show abundant evidence for magma mixing and thermochemical disequilibrium. Sparse basaltic andesites originated through mixing of observed mafic and felsic lavas rather than fractionation. Plagioclase phenocrysts from all lava types have uniform core (An(similar to 39)) and variable rim (An(39-64)) compositions, suggesting plagioclase feldspars from a common magma reservoir are present in all erupted lavas. An-rich crystal rims are regularly enriched in Mg, Fe and Ti, indicating mafic recharge and magma mixing. Mixing timescales determined by diffusion modeling of Mg profiles across core-rim boundaries suggest recharge to eruption occurs on the order of up to similar to 45 days. Thermobarometric calculations constrain shallow crustal storage of dacite to 1.5-2 kbar (similar to 5 km) and 800-890 degrees C, with deeper reservoirs for more mafic magmas (up to 35-40 km for basalts). Abundant disequilibrium textures (sieve-textured zones, oscillatory zoning, resorbed and patchy-zoned cores) indicate mobilization of a homogeneous crystal-rich dacitic reservoir by injection of mafic magma. We suggest that incomplete and dynamic physical mixing at shallow crustal levels results in distinct crystal morphologies, some of which record punctuated ascent and storage, while others are erupted rapidly after the influx of new magma.