Study on the large scale strike slip movement along the Maizuru Tectonic Belt

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The Purpose of this study is to clarify the substantive large-scale strike slip tectonics along the Maizuru Tectonic Belt, Inner Zone of Southwest Japan. Tenrane Analysis of Maizuru Belt, Origin of the Pre-Cretaceous Granitic rocks and structural analysis of the melange zone have been done for the above.The results are summarized as follows:(1) Analytical system for EPMA-Dating was established using JEOL JXA-8200 type EPMA in Hiroshima University.(2) SHRIMP dating was carried out for zircons from Nioki Granite in the Asaji Area, Eastern Kyusyu. The result shows that the huge tectonic rearrangement was occurred during Early Cretaceous time in Southwest Japan.(3) Detailed geological mapping and structural analysis revealed that the Maizuru Terrane in the Yoshiwa Area, western Chugoku Province has been developed as an dextral strike-slip tectonic melange zone with exotic blocks of non-metamorphic formation and metamorphic rocks.(4) Geo-chronological and structural geological study for the Northern Zone of the Maizuru Terrane revealed that the Zone could be correlative to the Kanka Massif Southwestern Primoye, Russia.(5) Detailed geological mapping, petrological and geo-chronological study revealed that the Tanohara-gawa Formation and ophiolitic complex in the Gotsu area, Shimane Prefecture were correlative to Maizuru Formation and Yakuno ophiolite respectively.(6) EPMA dating for the detrital zircon and monazite from the Triassic formations in the Maizuru Terrane showed that the provenance of the Eastern and Western parts were attributed to the Kanka Massif and North-China Block respectively.(7) The above mentioned result were strongly suggest that the large-scale dextral strike slip movement up to 500 km had been occurred along the Maizuru Tectonic Belt during Jurassic to Early Cretaceous time.