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HIGH RESOLUTION CYCLESTRATIGRAPHY BASED ON DARK ANDLITGT COLOR-BANDED CLAYLAYERS

基于深色和浅色带粘土层的高分辨率旋回地层学

基本信息

批准号：
04402014
负责人：
KOIZUMI Itaru
金额：
$ 11.84万
依托单位：
HOKKAID UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04402014/
关键词：
JAPAN SEA DARK AND LIGHT LAYERS EUSTATIC SEALEVEL CHANGES TSUSIMA WARM CURRENT MILANKOVICH CYCLE DANSGAAR-OESCHGER OSCILATION ODP EAST CHINA SEA COASTAL WATER 珪藻群集氷期-間氷期氷河性海水準変動対馬海峡ミランコビッチサイクルダンスガード・オイッシャーサイクル対馬暖流深層水循環

项目摘要

LATE QUATERNARY SEDIMENTS RECOVERED BY THE ODP LEG127 FROM THE BASINAL SITES OF THE JAPAN SEA ARE CHARACTERIZED WITH DISTINCTLY DARK AND LIGHT COLOR-BANDED CLAY.THICKNESS OF THE DARK AND LIGNT LAYERS VARIES FROM A CENTIMETER TO MORE THAN 2 METERS.THESE DARK AND LIGHT LAYERS ARE CORRELATABLE AND SYNCHRONOUS BASIN WIDE,SUGGESTING THEY RECORD SOME SORT OF REGIONAL OR GLOBAL PALEOENVIRONMENTAL CHANGES TO WHICH THE JAPAN SEA RESPONDED AS A SINGLE SYSTEM.IN ORDER TO UNDERSTAND THE IMPLICATION OF THESE DARK AND LIGNT LAYERS,WE ANALYZED LATE QUATERNARY SAMPLES.INFLOW OF THE TSUSIMA WARM CURRENT THROUGH THE TSUSIMA STRAIT WAS SIGNIFICANT DURING SEA LEVEL HIGHSTANDS WHEN HIGH SALINITY OF THE SURFACE WATER OF THE JAPAN SEA ALLOWED INTENSIVE DEEP WATER PRODUCTION AND VENTILATION OF THE BOTTOM.DURING INTERMEDIATE STANDS,THE EAST CHINA SEA COASTAL WATER PROPAGATED TO THE MOUTH OF THE TSUSIMA STRAIT AND FLOWED INTO THE SEA.DUE TO ITS LOWER SALINITY,THE INFLOW OF THE COASTAL WATER CAUSED WEAK DENSITY STRATIFICATION AND SUBDUED PRODUCTION OF DEEP WATER,WHICH RESULTED IN ANOXIC TO EUXINIC BOTTOM WATER CONDITION.DURING THE VERY LOWSTANDS,THE JAPAN SEA WAS NEARLY ISOLATED AND THE SURFACE WATER SALINITY DRASTICALLY DECREASED,CAUSING STRONG DENSITY STRATIFICATION,WHICH RESULTED IN STABLE EUXINIC BOTTOM WATER CONDITION.HIGH RESOLUTION ANALYSES OF THE DARK AND LIGHT LAYERS SUGGESTED THAT MILANKOVICH CYCLE RESULTING FROM THE EARTHS ORBITAL ELEMENTS AS WELL AS DANSGAARD-OESCHGER OSCILLATION REPORTED FROM GREENLAND ICE CORES ARE RECORDED IN THE JAPAN SEA SEDIMENTS AS VARIATION IN ORGANIC CARBON CONTENT,DIATOM ABUNDANCE CHANGES,AND CHANGES IN KOSA FRACTION WITHIN DETRITAL COMPONENT.IT WAS ALSO SUGGESTED THAT PALE-OCEAN CIRCULATION HAS BEEN MOST SENSITIVE TO SEA LEVEL CHANGES DURING INTERMEDIATE STANDS.

日本海晚第四纪沉积物的特征是暗色和浅色条带明显，暗色和浅色层厚度从1厘米到2米以上不等，暗色和浅色层是可共混的，在整个海盆范围内是同步的。它们记录了日本海作为一个单一系统所响应的某些区域或全球性的古环境变化。本文分析了晚第四纪地层样品。在海平面上升期间，当日本海表层海水的高盐度允许深层水的强烈产生和底部的通风时，Tsusima暖流通过Tsusima海峡的流入是显著的。在中期，东海沿岸水传播到Tsusima海峡口并流入大海。由于其盐度较低，沿岸水的流入造成了弱的密度分层和深水的潜生，使深水处于缺氧-缺氧的底层水状态，在极低水位期间，日本海几乎被孤立，表层水盐度急剧下降，造成了强的密度分层，暗、亮层的高分辨率分析表明，米兰科维奇循环与地球轨道元素和Dansgaard循环一样，日本海沉积物中的Oeshger振荡记录了格陵兰冰芯中有机碳含量、硅藻丰度和碎屑组分中Kosa组分的变化，并表明古海洋振荡对中间阶段的海平面变化最为敏感。