TY - JOUR
T1 - Amphibole growth from a primitive alkaline basalt at 0.8 GPa
T2 - Time-dependent compositional evolution, growth rate and competition with clinopyroxene
AU - Bonechi, Barbara
AU - Perinelli, Cristina
AU - Gaeta, Mario
AU - Tecchiato, Vanni
AU - Fabbrizio, Alessandro
N1 - Funding Information:
We are grateful to Keith Daniel Putirka and Alexander Simakin for their useful and constructive comments. The Editor, Michael Roden, is acknowledged for the editorial work. We thank Luca Ziberna (BGI Bayreuth) for preparing APR16GL sample. We thank M. Albano (CNR-IGAG), Dr. R. Jedlicka (Institute of Petrology and Structural Geology, Charles University of Prague) and M. Serracino (CNR-IGAG) for assistance during SEM and EMPA analytical sessions. This article is a contribution of the project “Dipartimenti di Eccellenza" of the Earth Science Department, Sapienza University of Rome, supported by the Italian Ministry of Education, University and Research .
Funding Information:
This research has been conducted with the financial support of the HP-HT Laboratory of the Earth Science Department, Sapienza University of Rome and with the financial support of the project M_011177_14_D_MAGRI_10-MIUR Fund for student support and mobility funded to B.B. by Sapienza University of Rome. A.F. acknowledges support from the GACR (Project 18-01982S).We are grateful to Keith Daniel Putirka and Alexander Simakin for their useful and constructive comments. The Editor, Michael Roden, is acknowledged for the editorial work. We thank Luca Ziberna (BGI Bayreuth) for preparing APR16GL sample. We thank M. Albano (CNR-IGAG), Dr. R. Jedlicka (Institute of Petrology and Structural Geology, Charles University of Prague) and M. Serracino (CNR-IGAG) for assistance during SEM and EMPA analytical sessions. This article is a contribution of the project “Dipartimenti di Eccellenza" of the Earth Science Department, Sapienza University of Rome, supported by the Italian Ministry of Education, University and Research.
Funding Information:
This research has been conducted with the financial support of the HP-HT Laboratory of the Earth Science Department, Sapienza University of Rome and with the financial support of the project M_011177_14_D_MAGRI_10-MIUR Fund for student support and mobility funded to B.B. by Sapienza University of Rome . A.F. acknowledges support from the GACR (Project 18-01982S ).
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2020/2
Y1 - 2020/2
N2 - Amphibole growth rates were experimentally determined at hydrous (3.3–4.2 wt% H2O), isobaric (0.8 GPa) conditions, variable temperature (1030 and 1080 °C) and dwell time (0.25, 3, 6, and 9 h), using as starting material a primitive alkaline basalt from Procida island (Campi Flegrei Volcanic District, south Italy). Amphibole growth rates decrease from 1.5·10−7 to 2.9·10−8 cm s−1 as the duration of the experiments increase from 0.25 to 9 h. Moreover, increasing both temperature and water content leads to similar growth rate increase at constant dwell time. The comparison between amphibole and clinopyroxene growth rates determined at the same experimental conditions reveals for amphibole a faster growth relatively to the coexisting clinopyroxene, regardless of the dwell time. Furthermore, the experimental time appears to be a critical parameter for the composition of synthetic amphiboles; specifically, edenite is the dominant composition in short experiments (≤3 h), particularly, at low temperature (1030 °C), whereas the magnesiohastingsitic amphibole becomes progressively more important shifting towards longer duration and higher temperature run conditions. The magnesiohastingsite, on the basis of the amphibole-liquid Fe-Mg exchange coefficient values, results to be the compositional term representative of amphibole-melt equilibrium at the investigated P-T-H2O conditions. Finally, experimental growth rates from this study have been used to investigate the crystallization time of natural amphiboles and clinopyroxenes from the Oligo-Miocene cumulates of north-western Sardinia (i.e. Capo Marargiu Volcanic District, Italy), yielding crystallization times of 1.46–3.12 yr.
AB - Amphibole growth rates were experimentally determined at hydrous (3.3–4.2 wt% H2O), isobaric (0.8 GPa) conditions, variable temperature (1030 and 1080 °C) and dwell time (0.25, 3, 6, and 9 h), using as starting material a primitive alkaline basalt from Procida island (Campi Flegrei Volcanic District, south Italy). Amphibole growth rates decrease from 1.5·10−7 to 2.9·10−8 cm s−1 as the duration of the experiments increase from 0.25 to 9 h. Moreover, increasing both temperature and water content leads to similar growth rate increase at constant dwell time. The comparison between amphibole and clinopyroxene growth rates determined at the same experimental conditions reveals for amphibole a faster growth relatively to the coexisting clinopyroxene, regardless of the dwell time. Furthermore, the experimental time appears to be a critical parameter for the composition of synthetic amphiboles; specifically, edenite is the dominant composition in short experiments (≤3 h), particularly, at low temperature (1030 °C), whereas the magnesiohastingsitic amphibole becomes progressively more important shifting towards longer duration and higher temperature run conditions. The magnesiohastingsite, on the basis of the amphibole-liquid Fe-Mg exchange coefficient values, results to be the compositional term representative of amphibole-melt equilibrium at the investigated P-T-H2O conditions. Finally, experimental growth rates from this study have been used to investigate the crystallization time of natural amphiboles and clinopyroxenes from the Oligo-Miocene cumulates of north-western Sardinia (i.e. Capo Marargiu Volcanic District, Italy), yielding crystallization times of 1.46–3.12 yr.
KW - Amphibole growth rate
KW - Campi flegrei
KW - High pressure
KW - Primitive alkaline basalt
UR - http://www.scopus.com/inward/record.url?scp=85076597519&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2019.105272
DO - 10.1016/j.lithos.2019.105272
M3 - Article
AN - SCOPUS:85076597519
SN - 0024-4937
VL - 354-355
JO - Lithos
JF - Lithos
M1 - 105272
ER -