Detrital zircon multi-chronology, provenance, and low-grade metamorphism of the Cretaceous Shimanto accretionary complex, eastern Shikoku, Southwest Japan: Tectonic evolution in response to igneous activity within a subduction zone

Island Arc ◽  
2017 ◽  
Vol 26 (6) ◽  
pp. e12218 ◽  
Author(s):  
Hidetoshi Hara ◽  
Yoshihiro Nakamura ◽  
Kousuke Hara ◽  
Toshiyuki Kurihara ◽  
Hiroshi Mori ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Detrital Zircon ◽  
Tectonic Evolution ◽  
Low Grade ◽  
Accretionary Complex ◽  
Southwest Japan ◽  
Grade Metamorphism ◽  
Igneous Activity

scholarly journals Progressive Low-Grade Metamorphism Reconstructed from the Raman Spectroscopy of Carbonaceous Material and an EBSD Analysis of Quartz in the Sanbagawa Metamorphic Event, Central Japan

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 854
Author(s):  
Hidetoshi Hara ◽  
Hiroshi Mori ◽  
Kohei Tominaga ◽  
Yuki Nobe
Keyword(s):  
Raman Spectroscopy ◽  
Carbonaceous Material ◽  
Metamorphic Event ◽  
Ebsd Analysis ◽  
Low Grade ◽  
Accretionary Complex ◽  
Metamorphic Complex ◽  
Central Japan ◽  
Grade Metamorphism ◽  
Quartz Grains

Low-grade metamorphic temperature conditions associated with the Sanbagawa metamorphic event were estimated by the Raman spectroscopy of carbonaceous material (RSCM) in pelitic rocks and an electron backscatter diffraction (EBSD) analysis of the quartz in siliceous rocks. Analytical samples were collected from the Sanbagawa metamorphic complex, the Mikabu greenstones, and the Chichibu accretionary complex in the eastern Kanto Mountains, central Japan. Previously, low-grade Sanbagawa metamorphism was only broadly recognized as pumpellyite–actinolite facies assigned to the chlorite zone. The RSCM results indicate metamorphic temperatures of 358 °C and 368 °C for the chlorite zone and 387 °C for the garnet zone of the Sanbagawa metamorphic complex, 315 °C for the Mikabu greenstones, and 234–266 °C for the Chichibu accretionary complex. From the EBSD analyses, the diameter of the quartz grains calculated by the root mean square (RMS) approximation ranges from 55.9 to 69.0 μm for the Sanbagawa metamorphic complex, 9.5 to 23.5 μm for the Mikabu greenstones, and 2.9 to 7.3 μm for the Chichibu accretionary complex. The opening angles of the c-axis fabric approximate 40–50°, presenting temperatures of 324–393 °C for the Sanbagawa metamorphic complex and the Mikabu greenstones. The temperature conditions show a continuous increase with no apparent gaps from these low-grade metamorphosed rocks. In addition, there exists an empirical exponential relationship between the estimated metamorphic temperatures and the RMS values of the quartz grains. In this study, integrated analyses of multiple rock types provided valuable information on progressive low-grade metamorphism and a similar approach may be applied to study other metamorphic complexes.

Sedimentary and Tectonic Evolution of a Trench-Slope Basin in the Nankai Subduction Zone of Southwest Japan

2003 ◽  
Vol 73 (4) ◽  
pp. 589-602 ◽  
Author(s):  
M. B. Underwood ◽  
G. F. Moore ◽  
A. Taira ◽  
A. Klaus ◽  
M. E.J. Wilson ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Tectonic Evolution ◽  
Southwest Japan ◽  
Nankai Subduction Zone ◽  
Trench Slope
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