SILURIAN AND DEVONIAN CORALS OF JAPAN

Abstract

Coral assemblages and their faunal sequence for the Silurian and Devonian in four major regions of Japan are reviewed. In Yokokurayama the G, fauna with Hatysttes is Early to Middle Silurian and the G. fauna with Schedohatysttes is mainly Late Silurian. The Kawauchi Formation of Hikoroichi corresponds to G, and a part of G,. The Okuhinotsuchi Formation of Arisu is mainly correlatable with the G,. The Ohno fauna of Hikoroichi with Xystrtphyttum and the FUkuji fauna are both Early Devonian in age, but their composition is quite different from each other. The Nakazato fauna of Hikoroichi is Middle Devonian. These faunas are composed mostly of cosmopolitan genera. The development of coral faunas may indicate the strong contrast in litho- and biofacies between the Pacific side (outer zone of Southwest Japan and Northeast Japan) and the Japan Sea side (inner zone of Southwest Japan) during the Silurian and Devonian. Key w 0 r d s: coral biostratigraphy, paleogeography, Silurian, Devonian, Japan.