Late Cenozoic paleoceanographic changes in the adjacent seas of the Ryukyu Islands.

1. 从宫古群岛以东约2200米水深的海沟斜坡上收集的柱状岩芯[KT84-14-Pl]：这个416英寸长的岩芯记录了过去15万年的许多古海洋条件，根据对底栖有孔虫动物群、钙质纳米浮游生物区系、浮游生物和底栖有孔虫测试的氧和碳稳定同位素、化学成分（特别是碳酸盐）和两个灰层的分析来判断。这项综合研究的手稿已准备好提交给《海洋微古生物学》杂志。1990年初发表了一篇关于地核底栖有孔虫的163种（包括3个新属和10个新种）的专著。从石垣群岛以南2488米水深的海沟斜坡上收集的活塞岩芯[RN87-PC4]：经证实，这个356厘米长的岩芯是由灰层和钙质纳米浮游生物形成的，大约在9万年前。与KT84-14-P1相比，更多的水化变化的影响较小，可能是因为该岩心的位置更靠南。在水深2486 m的喀喇玛裂口东南海沟斜坡上采集的活塞岩芯[RN89-PC3]：这个长386 cm的伸缩岩芯从三方面证据来看，似乎记录了过去约37万年的古海洋状况；浮游有孔虫、钙质纳米浮游生物地层和灰层的氧同位素测量。浮游有孔虫三角洲^<18>响应冰川变化而发生了变化，尽管与KT84-14-P1相比没有观察到更微妙的波动。与KT84-14-P1.4不同，底栖有孔虫动物群也具有类似的责任，主要组成类群在核心中连续出现。在冲绳群岛南部广泛发育的岛尻群，被认为是7 ~ 1.7 Ma期间的海沟斜坡沉积物。然而，根据其底栖有孔虫的初步研究，认为海沟的斜坡条件与现在或第四纪晚期不同。少

1. Piston core [KT84-14-Pl] collected from the trench slope east off the Miyako Islands at the water depth of about 2,200 m: This 416 a long core has recorded many paleoceanographic conditions during the past 150,000 years, judging from analyses of benthic foraminiferal faunas, calcareous nannoplankton floras, oxygen and carbon stable isotopes of planktonic and benthic foraminiferal tests, chemical compositions (particularly carbonate) , and two ash layers. A manuscript of this synthetic study is prepared for submitting to the journal, Marine Micropaleontology. A monograph described 163 taxs (three new genera and 10 new species included) of benthic foraminifera from the core was published in early 1990.2. Piston core [RN87-PC4] collected from the trench slope south off the Ishigaki Islands at the water depth of 2,488 m: It is verified that this 356 cm long care attains to about 90,000 years ago by an ash layer and calcareous nannoplanktons. Benthic foraminiferal change against the glac … More iation change is less responsible than the case of KT84-14-P1, probably because of more southerly location of this core.3. Piston core [RN89-PC3] collected from the trench slope southeast off the Kerama Gap at the water depth of 2,486 m: This telescopic core (386 cm long) seems to have recorded the paleoceanographic situation for the past about 370,000 years based on three fold evidences; oxygen isotope measurements of planktonic foraminifera, calcareous nanno-plankton stratigraphy, and an ash layer. Planktonic foraminiferal delta^<18> has changed in response to glaciation change, although more delicate fluctuation is not observed in comparison with KT84-14-P1. Benthic foraminiferal fauna also similar responsibility and the major component taxa occur rather continuously through the core differing from the case of KT84-14-P1.4. The Shimajiri Group, which is broadly developed in the southern part of the Okinawa Islands, has been regarded as the trench slope sediments during the period from 7 Ma to 1.7 Ma. According to preliminary study of its benthic foraminifera, however, it is suggested that the trench slope condition differs from that of the present day or the latest Quaternary period. Less