Large-scale overturned structure of the Northern Chichibu Belt in western Shikoku, Southwest Japan

Tomohiro Tsuji, Masayuki Sakakibara
2008 Chishitsugaku zasshi  
A Jurassic accretionary complex within the Northern Chichibu Belt, Yanadani area, western Shikoku, is divided into three distinct geologic units units , , and based on the constituent rocks and geologic structure. Unit is characterized by pelitic mélange containing blocks of greenstone, chert, limestone, and terrigenous clastic rocks. Unit consists mainly of psammitic and pelitic phyllites, and Unit consists of large blocks of greenstone-limestone complex with alternating beds of sandstone,
more » ... s of sandstone, mudstone, and pelitic mélange. The contacts between the units are northward-dipping faults. Here, we propose a method of analyzing grading structure, and there by younging direction, which involves grain-size measurements under the microscope. The younging directions of coherent sequences and pillow lava were determined at localities. These data reveal consistent younging directions within large-scale blocks, demonstrating that the strata of Units and , and the terrigenous clastic rocks of Unit are overturned, younging to the south. In contrast, the greenstone-limestone complex within Unit is not overturned, and youngs to the north. This large-scale overturned structure within the Northern Chichibu Belt is interpreted to represent a large-scale overturned fold. Abstract
doi:10.5575/geosoc.115.1 fatcat:yviny3ajujemjj7bdug2uoty6e