Preliminary analysis of grain-size populations with environmentally sensitive terrigenous components in marginal sea setting

Terrigenous components were separated from the bulk sediment of Core A7 from the Okinawa Trough and Core A37 from the Ryukru Trench and grain-size distributions of these sub-samples were analyzed.Based upon and analysis of the grain-size data of the two sedimentary sequences,grain-size populations are identified to be sensitive to sedimentary environmental changes.The modal values and size ranges of the two main grain-size populations in Core A7 are evidently different from those of Core A37,indicating the spatial variability of sediment sources and transport processes between the two places.The downcore variations in the content of the environmentally sensitive sgrain-size populations reveal that during the accumulation of sedimentary material the environment remained relatively stable at the site where Core A7 was collected,except for the apparent events for the formation of two turbidite layers and a volcanic ash layer.However,the sedimentary sequence of Core A37 shows six sedimentary cycles,indicating a highly variable sedimentary environment at this location.     

冲绳海槽南部表层以沉积中的底栖有孔虫

研究了冲绳海槽南部３３个表层样，共分析鉴定底栖有孔虫９３属１３９种，建立了三个底栖有孔虫组合和两个亚组合：１．Ｃｉｂｉｃｉｄｏｉｄｅｓ ｐｒａｅｃｉｎｃｔａ－Ｐｙｒｇｏ ｓｐｐ．组合；（２）Ｃｉｂｉｃｉｄｏｉｄｅｓ－Ｕｖｉｇｅｒｉｎａ组合１：（３）Ｃｉｂｉｃｉｄｏｉｄｅｓ ｗｕｅｌｌｅｒｓｔｏｒｆｉ亚组合；ｂ；Ｈｙａｌｉｎｅａ ｂａｌｔｈｉｃａ－Ｂｕｌｉｍｉｎａ ａｃｕｌｅａｔａ亚组合；（３）Ｅｇ     

城口—鄂西海槽西侧长兴组沉积相特征及其展布规律

在前人对川东地区长兴组沉积相研究成果的基础之上,运用沉积学及层序地层学理论,结合野外剖面的观察和室内岩石薄片的鉴定以及岩石学、古生物学等沉积相标志,分析研究区长兴组沉积相特征。结合城口—鄂西海槽西侧重点勘探区域最新的钻井资料,以及地震解释资料,依据地层等时切片技术,绘制出层序地层格架内沉积相展布图;并分析其演化规律特征。研究表明:长兴组沉积早期发育碳酸盐缓坡沉积模式,长兴中-晚期发育碳酸盐台地沉积模式。其中,碳酸盐缓坡沉积常以薄-中层泥质灰岩与龙潭组顶部的灰岩-硅质条带灰岩互层相接触。研究区长兴组中-晚期碳酸盐台地沉积主要发育了开阔台地相、台地边缘相、台地前缘斜坡相以及盆地相沉积。结合地质资料和地震解释成果分析,进行研究区长兴组有利储集相带预测;并依据条件划分为3个有利相带等级,其中礁滩发育部位为最有利储集相带。     

东海深海生物综合科考纪实（中）

奇形怪状的深海鱼类人类的祖先早在原始社会就已经对鱼类有所了解,然而海洋牛物学家确认深海中有鱼类存侄的事实还足近100多年之事。深海何类的生存环境是世界上最特殊、也是最严峻的。同样,栖息在东海大陆坡和冲绳海槽西侧（水深150～1000余米）的大陆深海鱼类,也常年处于黑暗（水深200米处已一片漆黑）、低温（温度低于4～7℃）、高压（水深每增加10米就会增加1个大气压）、贫食（除中深海区有少量浮游动物外,     

冲绳海槽火山岩同位素特征及铀系组分法测年

借助多种分析方法,对采自冲绳海槽北段和中段的火山岩进行了常量元素、稀土元素、Sr-Nd同位素组成分析及铀系组分法年龄测定,在此基础上对此地区的海槽岩浆的起源、演化及岩石类型进行了研究.结果表明(1)海槽晚更新世(大约10万年)以来有一期广泛的酸性火山喷发活动;(2)受板块俯冲的控制,此期火山活动年龄按照与琉球岛弧距离的由近到远而由新到老;(3)海槽北、中段岩浆演化过程相似,其下很可能存在有巨大的、统一的岩浆房,但与海槽南段岩浆作用差异明显,岩浆物质很可能来源于PREMA地幔源区;(4) 此地区的黑色浮岩为钙碱性系列流纹岩,岩石化学组成与海槽产出的白色浮岩相似,形成年代为17.7±2.1 ka.     

神秘的海底黑烟囱

<正>作为我国最先进的一艘综合海洋科考船,国家大科学装置"科学"号考察船的科考活动备受瞩目。它的首航承担着中国科学院战略性先导科技专项"热带西太平洋海洋系统物质能量交换及其影响"(WPOS专项)和国家973项目的"西太平洋海底热液调查"任务。     

Magnetic properties of different grain-sized particles of sediments from the Okinawa Trough and their relationships to sedimentary environment

Multiple magnetic parameters were measured for nine different grain-sized fractions separated from the sediment samples that are representatives of four different sedimentary environments of the Okinawa Trough. Based on the measured results, the contributions of different grain-sized particles to total magnetic susceptibility of bulk sediments, the magnetic mineral assemblage and magnetic domain state as well as their relationships to sedimentary environment were discussed. Our research shows that the magnetic mineral is dominated by magnetite with a small amount of hematite and is primarily in pseudo-single-domain state. That indicates that the different sedimentary environments in the Okinawa Trough have certain correlation in material provenance. The magnetic minerals enrich in different grain-sized particles in response to different sedimentary environments. The contribution of the grain sizes from coarse to fine to coarse and fine to the magnetic susceptibility from the west to the east is in accordance with terrigenous material transportation from continental shelf of the East China Sea to the Okinawa Trough. It also shows difference in magnetic properties as a result of some environmental factors.     

镇巴区块飞仙关组沉积演化及其对储层的控制作用

镇巴区块台地边缘颗粒灰岩储层是重要的勘探层位。根据构造演化背景,通过沉积演化及沉积相分析,认为台地边缘亮晶鲕粒灰岩、亮晶砂屑灰岩储层的展布严格受有利沉积相带所控制,随着城口海槽的成生、发展、萎缩,台缘鲕滩不仅向广海(北大巴)方向发生了迁移,而且发育层位逐步抬高,具有明显穿时性特征。镇巴区块铁溪万源区带飞一段-飞二段发育厚层状鲕粒坝储集层,单层厚度为22~40 m,分布较为稳定,是优质储集层。     

冲绳海槽铜锌黑烟囱枝状构造成因机制及其地质意义

研究表明，冲绳海槽铜锌黑烟囱内发育的枝状构造矿物成分为闪锌矿，在枝状闪锌矿内发育片状黄铜矿鱼骨状构造.枝状构造闪锌矿及其内部生长的鱼骨状黄铜矿具有从烟囱外壁向内部生长的特征.从对该烟囱进行的电子探针分析结果看，组成该烟囱的主要硫化物单矿物（黄铜矿、方铅矿、黄铁矿等）的Cu/Zn值，从外壁至中央通道，具有低-高-低的特征，在该烟囱枝状构造和外壁过渡带达到最高；闪锌矿中特征不明显.Au，As等元素与此有相似的特征.据以上这些特征推断在该烟囱初始喷发时，富含硫化物的高温流体与海水接触，造成了异常高的过饱和度增高，并发生快速冷却结晶，形成闪锌矿淬火构造.外壁的低渗透性阻隔了高温型热液从管壁向海水的扩散，使得高温热液有较为充足的时间在靠近外壁的位置和早期枝状闪锌矿进行物质交换取代，从而有利于在外壁和枝状构造接触部位形成Au，Cu和As异常高富集.