A revisit to the Higo terrane, Kyushu, Japan: The eastern extension of the North China–South China collision zone

Geochronology and REE geochemistry of zircon and garnet in pelitic gneisses from the Higo metamorphic terrane, Kyushu, Japan: Constraints on the timing of high–temperature metamorphism

“…3b, 3d, and 3g). These distinct ages from detrital Zrns might indicate metamorphism timing, which is quite consistent with previous reports (Sakashima et al, 2003;Takagi and Arai, 2003;Dunkley et al, 2008;Maki et al, 2014;Osanai et al, 2017;Suga et al, 2017).…”

“…The subsequent retrograde stage promoted new Zrn crystallization from melts and Grt breakdown at~110 Ma, finally involving granitic intrusion into pelitic gneisses at~105 Ma. Although the timing of the HT metamorphism in the Higo metamorphic terrane (~110-120 Ma) is consistent with that of previous studies (e.g., Sakashima et al, 2003;Takagi and Arai, 2003;Dunkley et al, 2008;Maki et al, 2014;Osanai et al, 2017;Suga et al, 2017), this study reconfirmed the rapid HT metamorphism framework from detailed observation of Zrn internal textures, REE chemistry, and U-Pb ages, providing critical information to understand the tectonic evolution of this terrane.…”

“…The youngest detrital Zrn cores shows a maximum depositional age pooled at~130 Ma, approximately 50 Ma younger than previously reported by Suga et al (2017). In contrast, the rim domains, which truncate or overgrow the relic cores, and the domains with a variety of internal zoning such as banded oscillatory and blurred zoning and unzoned to faint oscillatory zoning show concentrated ages of~110 and 120 Ma, with Th/U ratios of 0.06-1.21 (Figs.…”

“…It consists of high-grade metamorphic rocks up to UHT granulite-facies that are characterized by a clockwise P-T evolution and peak metamorphic conditions of 7.8-9.0 kbar and 900-960°C (Osanai et al, 1998). Previously, this terrane was proposed to have metamorphosed at~260-230 Ma (Osanai et al, 1998;Hamamoto et al, 1999;Osanai et al, 2006); however, the recently conducted Zrn geochronology has suggested that the timing of HT-UHT metamorphism is approximately 110-120 Ma because of clustered age data (Sakashima et al, 2003;Takagi and Arai, 2003;Dunkley et al, 2008;Maki et al, 2014;Osanai et al, 2017;Suga et al, 2017). Though its metamorphic evolution in terms of petrography has been well understood, of which the prograde and retrograde metamorphic processes for each metamorphic zone were well reported on the basis of reaction textures, chemical zoning of minerals, and mineral inclusions in porphyroblasts (Hamamoto et al, 1999;Maki et al, 2004;Osanai et al, 2006), it is still obscured in term of P-T-t evolution because of the lack of information regarding the timing of the prograde and retrograde stages.…”

Secular Variation of Early Cretaceous Granitoids in Kyushu, SW Japan: The Role of Mélange Rocks as a Possible Magma Source

“…Although there is along strike subduction, Early Cretaceous magmatism in NE Asia may be related to subduction of the Izanagi plate, whereas in eastern China, it is related to subduction of the Paleo-Pacific plate (Maruyama et al, 1997). Moreover, it is still debated whether the paleogeographic position of Korea and SW Japan belongs to the North China craton or the South China craton (Osanai et al, 1999(Osanai et al, , 2006Ishiwatari and Tsujimori, 2003;Ernst et al, 2007;Oh and Kusky, 2007;Omori and Isozaki, 2011;Suga et al, 2017).…”