摘要
琉球群岛东部海区沉积物中富含大量火山碎屑矿物、岛屿岩石遭受风化蚀变形成的普通角闪石以及水生的铁锰微结核,其重矿物种类、特征、组合分区等与火山作用、沉积环境、地形、物质来源等内外生因素密切相关。通过对本区重矿物的种类、特征及组合分区的研究,初步判断位于研究区北部、菲律宾板块向欧亚大陆俯冲而导致的正在活动的的琉球岛弧区为火山碎屑的主要源区,重矿物成分主要为水携成因来源,受同期火山作用控制;少量紫苏辉石来自先期形成的海岭或海底高原(如冲大东海岭、奄美海岭及九州海岭等)上的火山岩系,是经过剥蚀、搬运再沉积的产物;琉球群岛、九州等火山活动产物受海底高地等阻隔而在本区表现为向南或东南影响力逐渐减小;本区地质历史上的及正在进行的岩浆活动主要以基性及中性岩浆为主。此外,流经本区的黑潮对自生铁锰微结核的富集具有重要影响。
Sediments distributed over the area east of Ryukyu Islands are enriched in volcaniclastic minerals, hornblende and Fe Mn micro-nodules. Types, characteristics and provinces of heavy minerals are closely related to some endogenetic and exogenous factors, suah as volcanism, sedimentary environment, relief and material provenance. Based on the study of types, characteristics and provinces of heavy minerals, it is preliminarily inferred that the ongoing volcaniclastic material is from Ryukyu Islands arc, which is created by the subduction of Philippine plate beneath Eurasian plate; water is the main transportation mean for heavy minerals, the abundance of which is strongly controlled by contemporaneous volcanism. Low-abun- dance hypersthene originates from volcanic rocks on adjacent ridges or seafloor plateaus such as Oki- -Daito ridge, Amami ridge and Kyushu-Palau ridge, which experienced a series of processes such alteration, transportation and re-sedimentation. The abundance of volcaniclastic materials from Ryukyu Islands shows a decreasing trend southwards or southeastwards due to the obduction of seafloor plateaus; ongoing mag- matism or volcanic activity in geologic time is mainly represented by basic-intermediate magmatism. In ad- dition, Kuroshio plays a significant role in the enrichment of Fe-Mn micro-nodules.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2008年第5期21-28,共8页
Marine Geology & Quaternary Geology
基金
国家自然科学基金重点项目(40431002)
国家自然科学基金项目(40706030)
基本科研业务费专项资金项目(2007T09)
关键词
沉积物
重矿物
火山碎屑
火山作用
琉球群岛
sediments
heavy minerals
volcanic clast
volcanism
Ryukyu Islands
