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Paleobiological study of Ostracoda (Crustacea) in relation to paleogeographical changes of Kyushu to the Ryukyu Islands

介形类（甲壳类）古生物学研究与九州至琉球群岛古地理变化的关系

基本信息

批准号：
15540451
负责人：
IRIZUKI Toshiaki
金额：
$ 1.98万
依托单位：
Shimane University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

The aim of this study is to clarify the relationships between migration and speciation of embayment ostracodes and paleogeographical changes related to relative sea-level changes in Kyushu and the Ryukyu Islands on the basis of biological and paleontological methods. As no studies on recent ostracodes from small bays around the Tokara Strait, which is situated between Amami-ohshima and Tanega-shima Islands, surface sediment samples were collected from Kasari, Isu and Sumiyou Bays in Amami-ohshima Island, central Ryukyu in 2003, and those from Urauchi Bay and Namako Pond in Koshiki-jima Island, southern Kyushu in 2004, to make Recent ostracode faunal and biological analyses. Fossil ostracodes were also obtained especially from Pleistocene deposits in several areas in central Honshu to southern Kyushu. As a result, distribution patterns of embayment ostracodes such as Spinileberis, Bicornucythere, Neomonoceratina and Sinocytheridea were clarified in time and space as follows :1:Sinocytheridea, which is living in high-turbidity and low-salinity bays along the Chinese coast was dominant in Honshu to Kyushu during marine oxygen isotope stage(MIS) 15 to 11. It was extinct in most bays after MIS 10.2:Subtropical taxa (e.g., Neomonoceratina) migrated from the Ryukyu Islands to Kyushu at least until marine oxygen isotope stage(MIS) 12 and were dominant in Honshu to Kyushu during MIS 11 to 5.3.Subtropical taxa became extinct in inner bays along the Pacific side of Honshu and Kyushu because of the decreasing of water temperature during MIS 2.4.The Tokara Strait is the barrier for the subtropical species to migrate from Amami-ohshima Island to southern Kyushu.Thus, enclosed muddy bay ostracodes have been influenced by temporal changes of glacio-eustacy, location of the warm Kuroshio Current, depth and width of the Tokara Strait and the opening of local straits.

本研究的目的是澄清海湾介形类的迁移和物种形成之间的关系和古地理变化相关的相对海平面变化在九州和琉球群岛的生物和古生物学方法的基础上。2003年在琉球中部奄美大岛的笠利湾、伊须湾和隅游湾，以及2004年在九州南部越敷岛的浦内湾和Namako池采集了表层沉积物样品，对近几年来在奄美大岛和种子岛之间的吐噶喇海峡小海湾的介形类进行了区系和生物学分析。化石介形类也获得了特别是从更新世沉积在几个地区在中部本州南部九州。结果表明，湾口介形类如棘介形类、双角介形类、新单角介形类和中华介形类的时空分布格局如下：1.中华介形类生活在中国沿海沿着的高浊度、低盐度海湾中，在海洋氧同位素阶段（MIS）15 ~ 11，在本州至九州占优势。在MIS 10.2之后，它在大多数海湾中灭绝：亚热带分类群（例如，新单角藻（Neomonoceratina）至少在海洋氧同位素阶段（MIS）12之前从琉球群岛迁移到九州，MIS 11 - 5.3期间在本州-九州占优势。MIS 2.4期间，由于水温下降，本州和九州的太平洋侧沿着海湾的亚热带类群灭绝。因此，封闭的泥质海湾介形类受冰川海平面的时间变化、黑潮暖流的位置、吐噶喇海峡的深度和宽度以及当地海峡的开放程度的影响。