TY - JOUR
T1 - Kyanite-paragonite-bearing assemblages, Northern Fiordland, New Zealand
T2 - rapid cooling of the lower crustal root to a Cretaceous magmatic arc
AU - Daczko, N. R.
AU - Clarke, G. L.
AU - Klepeis, K. A.
PY - 2002/12
Y1 - 2002/12
N2 - Fiorland, New Zealand exposes the lower crustal root of an Early Cretaceous magmatic arc that now forms one of Earth's most extensive high-P granulite facies belts. The Arthur River Complex, a dioritic to gabbroic suite in northern Fiordland, is part of the root of the arc, and records an Early Cretaceous history of emplacement, tectonic burial, and high-P granulite facies metamorphism that accompanied partial melting of the crust. Late random intergrowths of kyanite, quartz and plagioclase partially pseudomorph minerals in the earlier high-T assemblages of the Arthur River Complex, indicating high-P cooling of an over thickened crustal root by c. 200 °C. The kyanite intergrowths are themselves partially pseudomorphed by paragonite, commonly in the presence of phengitic white mica. Biotite-plagioclase intergrowths that partially pseudomorph phengitic white mica and diopside-plagioclase intergrowths that partially pseudomorph jadeitic diopside, combined with published thermochronology results, are consistent with later rapid decompression. A short duration anticlockwise P-T path may be explained by the high-P juxtaposition of comparatively cool upper crustal rocks following their tectonic burial and under thrusting during the waning stages of Early Cretaceous orogenesis. This was then followed by the decompression giving the rapid exhumation within 20 Myr of peak metamorphism, as suggested by the isotopic data.
AB - Fiorland, New Zealand exposes the lower crustal root of an Early Cretaceous magmatic arc that now forms one of Earth's most extensive high-P granulite facies belts. The Arthur River Complex, a dioritic to gabbroic suite in northern Fiordland, is part of the root of the arc, and records an Early Cretaceous history of emplacement, tectonic burial, and high-P granulite facies metamorphism that accompanied partial melting of the crust. Late random intergrowths of kyanite, quartz and plagioclase partially pseudomorph minerals in the earlier high-T assemblages of the Arthur River Complex, indicating high-P cooling of an over thickened crustal root by c. 200 °C. The kyanite intergrowths are themselves partially pseudomorphed by paragonite, commonly in the presence of phengitic white mica. Biotite-plagioclase intergrowths that partially pseudomorph phengitic white mica and diopside-plagioclase intergrowths that partially pseudomorph jadeitic diopside, combined with published thermochronology results, are consistent with later rapid decompression. A short duration anticlockwise P-T path may be explained by the high-P juxtaposition of comparatively cool upper crustal rocks following their tectonic burial and under thrusting during the waning stages of Early Cretaceous orogenesis. This was then followed by the decompression giving the rapid exhumation within 20 Myr of peak metamorphism, as suggested by the isotopic data.
KW - Cooling
KW - High-P granulites
KW - Magmatic arc
KW - P-T path
KW - Thermobarometry
UR - http://www.scopus.com/inward/record.url?scp=0036907463&partnerID=8YFLogxK
U2 - 10.1046/j.1525-1314.2002.00421.x
DO - 10.1046/j.1525-1314.2002.00421.x
M3 - Article
AN - SCOPUS:0036907463
SN - 0263-4929
VL - 20
SP - 887
EP - 902
JO - Journal of Metamorphic Geology
JF - Journal of Metamorphic Geology
IS - 9
ER -