Geology of Akiyoshi

Abstract

Part Ⅰ of this paper is divided into three chapters. Chapter 1 concerns the fusulinid zones of the Akiyoshi limestone group. Six major fusulinid zones are described as Profusulinella zone, Fusulinella zone, Pseudoschwagerina zone, Parafusulina zone, Neoschwagerina zone and Yabeina zone. Fusulina Zone of upper Middle and Triticites Zone of Upper Pennsylvanian age are missing in the Akiyoshi limestone group. Chapter 2 considers the correlation of the fusulinid zones of the Akiyoshi limestone group with Pennsylvanian and Permian formations of not only other parts of Japan but also of Tethys Sea Region and North America. Stratigraphic relationships among fusulinid zones are also discussed in some detail. Chapter 3 concerns the stratigraphy of the Akiyoshi limestone group. To determine the stratigraphic order of succession twenty-seven sections are chosen and described. The geologic structure of the Akiyoshi limestone group derived from the distribution of fusulinid zones and the tectonic relationships between the Akiyoshi limestone group and non-calcareous Upper Paleozoic groups are also discussed in detai1. Based on the distribution of fusulinid zones, lithology of limestones and mode of occurences of fusulinid fossils, Permian epeirogenic movements in the Akiyoshi region are discussed.