Paleobiogeographical study on the Permian brachiopods of the Akiyoshi Terrane

1994年，对从秋吉石灰岩中采集的大量上石炭统腕足动物标本以及从大沙丘石灰岩中采集的下二叠统标本进行了研究。通过详细的野外调查，采集了二叠纪常盛组腕足类化石。为了比较阿曼二叠纪腕足动物群的区系特征，对阿曼二叠纪腕足动物群进行了研究和描述，并于1995年描述了晚石炭世早期的两种腕足动物Weiningia，讨论了它们的古生物地理意义。本文对秋吉西部邻区三叠纪矿群中的一种小舌属植物进行了鉴别和讨论。三叠纪的舌形虫对于研究二叠纪末海洋无脊椎动物最大规模的灭绝过程具有重要意义。对中二叠世常盛组腕足动物进行了讨论。经初步研究认为：常森腕足动物群与中国南方扬子地台中二叠世晚期至晚二叠世早期的腕足动物群关系密切。常盛腕足动物群的成分具有特提斯暖水区成分和高纬度冷水区成分混合的特点。这一结果已在1995年在加拿大萨德伯里劳伦森大学举行的第三届国际腕足动物大会上发表。为了弄清日本西南部上古生界的地质历史，将尽快对采集到的秋吉石灰岩群石炭纪腕足动物和常盛组二叠纪腕足动物进行描述。

In 1994 a huge number of collected materials on the Upper Carboniferous brachiopods from the Akiyoshi Limestone as well as the Lower Permian specimens from the Taishaku Limestone were examined. Permian brachiopods from the Tsunemori Formation have been collected with the detailed field survey. For the purpose of comparing the faunal character, Permian brachiopod faunas from Oman have been examined and described.In 1995 two species of early Late Carboniferous brachiopod Weiningia have been described and their paleobiogeographical significance was also discussed. A Lingula species was discriminated and discussed from the Triassic Mine Group, distiributed in the western neighboring region of Akiyoshi. The Triassic Lingula is very significant to consider the process of the largest mass extinction occured within marine invertebrates at the end of the Permian. The Middle Permian brachiopod from the Tsunemori Formation have been discussed. The preliminary research of them has been concluded as follows : The Tsunemori brachiopod fauna is closely related with that of the late Middle to early Late Permian of the Yangtze Platform in southern China. Elements of the Tsunemori brachiopod fauna are characterized by mixture of those in the warm water region of Tethys as well as the cool water in the high latitudal regions. This means that the Akiyoshi organic reef complex on a seamount probably collapsed the northern marginal region of the Yangtze Platform at the end of the Middle Permian or the begining of the Late Permian.These preliminary results have been presented and read in the 3rd International Brachiopod Congress held at the Laurentian University, Sudbury, Canada in 1995. The collected Carboniferous brachiopods from the Akiyoshi Limestone Group and the Permian brachiopods from the Tsunemori Formation will be described as soon as possible for the purpose of making clear the geologic history of the Upper Paleozoic of South west Japan.