Open AccessOn the use of nominally anhydrous minerals as phenocrysts in volcanic rocks: A review including a case study from the Carpathian–Pannonian Region
Author(s) -
Zsófia Pálos,
István Kovàcs,
Dávid Karátson,
Tamás Bíró,
Judit Sándorné Kovács,
Éva Bertalan,
Anikó Besnyi,
György Falus,
Tamás Fancsik,
Martina Tribus,
László Előd Aradi,
Csaba Szabó,
Viktor Wesztergom
Publication year - 2019
Publication title -
central european geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.253
H-Index - 24
eISSN - 1789-3348
pISSN - 1788-2281
DOI - 10.1556/24.62.2019.03
Subject(s) - phenocryst , plagioclase , geology , geochemistry , volcano , melt inclusions , pannonian basin , volcanic rock , anhydrous , earth science , mineralogy , quartz , paleontology , chemistry , organic chemistry
The past decade has seen a great number of studies dealing with magmatic water contents and how these could be retrieved by the nominally anhydrous minerals’ (NAMs) trace structural hydroxyl (water) contents. Constraints have been made to magmatic hygrometry with clinopyroxene and plagioclase. Although results suggest that the method is more flexible and reliable than melt inclusion studies, they also indicate that the trace hydroxyl contents could still be overprinted by syn- and post-eruptive processes. Clinopyroxenes can hold more structural hydroxyl than plagioclases. A comprehensive review is presented with the inclusion of all published results so far to compile the available pieces of information. As a case study, micro-FTIR measurements are made of a representative set of plagioclase phenocrysts from the Börzsöny Mts. (Carpathian–Pannonian Region). The samples were selected to represent the progress of the volcanic activity in time and space, considering the petrologic and geochemical evolution of volcanic products in well-defined volcanostratigraphic positions. The syn- and post-eruptive cooling rate seems to have the greatest effect on water retention. This means that the systematic investigation of water in volcanic phenocrysts can contribute to distinguish the slowly and rapidly cooling parts of the volcanostratigraphic units.