TY  - JOUR
A1  - Keyser, William
A1  - Tsai, Chin-Ho
A1  - Iizuka, Yoshiyuki
A1  - Oberhänsli, Roland
A1  - Ernst, W. G.
T1  - High-pressure metamorphism in the Chinshuichi area, Yuli belt, eastern Taiwan
JF  - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth
N2  - Tectonic blocks and slabs of mafic-ultramafic rocks are distributed discontinuously in the Yuli metamorphic belt of Taiwan. The blocks include rare omphacite metagabbros and gamet-epidote blueschists in the Wanjung and Juisui (Tamayen) areas, respectively. Such high-pressure (HP) mineral assemblages have been attributed to a mid-Miocene subduction event. However, the surrounding psammitic, pelitic and chloritic schists are the dominant greenschist-facies lithologies of the Yuli belt. In the Chinshuichi area, tectonic blocks are enclosed in garnet-bearing metapelites, suggesting elevated pressures. In this area, we recently discovered meta-plagiogranite containing the assemblage glaucophane + omphacite (X-Jd up to 039) + rutile + quartz, indicating P-T conditions near 13 kbar/550 degrees C. New equilibrium phase modeling of a garnet-paragonite mica schist and compositional isopleths for peak assemblage minerals garnet and phengite (Si = 3.33-3.37 pfu) indicate metamorphic conditions of 15.5-17 kbar/530-550 degrees C. These P-T estimates are higher than previously reported in the Yuli belt and suggest that both tectonic blocks and host metapelites underwent HP metamorphism. The juxtaposition of tectonic blocks and metapelites apparently occurred during the formation of a subduction-accretionary complex, followed by exhumation facilitated by a collisional event. These new findings imply that HP metamorphism was not limited to tectonic blocks, and instead played a significant role attending orogenesis in eastern Taiwan. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Equilibrium phase modeling
KW  - Omphacite
KW  - Glaucophane
KW  - Meta-plagiogranite
KW  - High-pressure metamorphism
KW  - Yuli belt
KW  - Tananao Complex
Y1  - 2016
U6  - https://doi.org/10.1016/j.tecto.2015.09.012
SN  - 0040-1951
SN  - 1879-3266
VL  - 692
SP  - 191
EP  - 202
PB  - Elsevier
CY  - Amsterdam
ER  -