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

本研究的目的是阐明日本西南部舞鹤构造带内带沿着的大规模走滑构造。（1）建立了广岛大学JEOL JXA-8200型电子探针测年分析系统。(2)对九州东部Asaji地区Nioki花岗岩中的锆石进行了SHRIMP测年。结果表明，早白垩世日本西南地区发生了巨大的构造重组。(3)详细的地质测绘和构造分析表明，中国西部吉瓦地区的舞鹤地体是一个右旋走滑构造混杂岩带，含有非变质建造和变质岩石的外来块体。(4)舞鹤地体北方带的年代学和构造地质研究表明，该带可能与俄罗斯普里莫耶西南部的坎卡地块相关。(5)详细的地质填图、岩石学和年代学研究表明，岛根县江津地区的田原川组和蛇绿杂岩分别与舞鹤组和八久野蛇绿岩相关。(6)舞鹤地体三叠纪地层中碎屑锆石和独居石的EPMA测年结果表明，舞鹤地体东部和西部的物源分别归属于冈贺地块和华北地块。(7)上述结果有力地表明，在侏罗纪-早白垩世期间，舞鹤构造带发生了长达沿着500 km的大规模右行走滑运动。

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.