TY - JOUR
T1 - Oxygen isotopes in titanite and apatite, and their potential for crustal evolution research
AU - Bruand, Emilie
AU - Storey, Craig
AU - Fowler, Mike
AU - Heilimo, Esa
AU - EIMF (Edinburgh Ion Micro-Probe Facility)
PY - 2019/6/15
Y1 - 2019/6/15
N2 - Oxygen isotope analysis of zircon, often combined with geochronology and Hf isotope analysis, has been pivotal in understanding the evolution of continental crust. In this contribution, we expand the use of underexplored accessory phases (titanite and apatite) by demonstrating that their oxygen isotope systems can be robust, and by developing geochemical indicators involving O isotopes and trace element concentrations to better constrain magma petrogenesis. These minerals have the advantage over zircon of being present in less evolved magmas and being more responsive to igneous processes and crustal metamorphism. We present new data on titanite, apatite and zircon from carefully-selected granitoids through geological time: the Phanerozoic high Ba-Sr granites (Caledonian province, Scotland), Archean sanukitoids (Karelia province, Finland) and a Neoproterozoic basalt-andesite-dacite-rhyolite suite (BADR; Guernsey, Channel Island). We demonstrate: (i) that δ 18O values of the studied accessory minerals are not affected by crystal fractionation, (ii) a strong correlation between δ 18O in all three accessory minerals, showing that apatite and titanite can faithfully record the magmatic δ 18O; (iii) that these accessory minerals can also record metamorphic and/or fluid circulation events during the syn- to post-magmatic history of granitoids.
AB - Oxygen isotope analysis of zircon, often combined with geochronology and Hf isotope analysis, has been pivotal in understanding the evolution of continental crust. In this contribution, we expand the use of underexplored accessory phases (titanite and apatite) by demonstrating that their oxygen isotope systems can be robust, and by developing geochemical indicators involving O isotopes and trace element concentrations to better constrain magma petrogenesis. These minerals have the advantage over zircon of being present in less evolved magmas and being more responsive to igneous processes and crustal metamorphism. We present new data on titanite, apatite and zircon from carefully-selected granitoids through geological time: the Phanerozoic high Ba-Sr granites (Caledonian province, Scotland), Archean sanukitoids (Karelia province, Finland) and a Neoproterozoic basalt-andesite-dacite-rhyolite suite (BADR; Guernsey, Channel Island). We demonstrate: (i) that δ 18O values of the studied accessory minerals are not affected by crystal fractionation, (ii) a strong correlation between δ 18O in all three accessory minerals, showing that apatite and titanite can faithfully record the magmatic δ 18O; (iii) that these accessory minerals can also record metamorphic and/or fluid circulation events during the syn- to post-magmatic history of granitoids.
KW - RCUK
KW - NERC
KW - NE/I025573/1
U2 - 10.1016/j.gca.2019.04.002
DO - 10.1016/j.gca.2019.04.002
M3 - Article
SN - 0016-7037
VL - 255
SP - 144
EP - 162
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -