马里亚纳海槽区粘土矿物组成及分布特征

根据７个岩芯粘土矿物的研究，马里亚纳海槽晚更新世以来的沉积物中主要粘土矿物是蒙皂石，其次是少量ＦｅＭｇ绿泥石和伊利石．蒙皂石和ＦｅＭｇ绿泥石主要是海底基性火山物质蚀变形成的自生矿物，伊利石主要是来自海槽北面和西北面陆上岩石的风化产物．蒙皂石由海槽北部向南部呈增加趋势，而伊利石则呈减少趋势．此外，在距今大约４５ｋａ～１０ｋａ形成的地层中蒙皂石呈减少趋势，伊利石则呈增加趋势．上述粘土矿物组成及分布主要与物质来源、火山活动、海底浊流以及古气候变化的影响有关．

Clay Mineral Composition and Distribution in the Mariana Trough

Clay minerals in the seven cores taken from the Mariana Trough during SONNE cruises 57 and 69 were studied by means of X-ray diffractometry. The results have revealed that smectite dominatees in the sediments deposited in the Mariana Trough since the Late Pleistocene and next comes a small amount of FeMg chlorite and illite. Smectite and FeMg chlorite are mainly authigenic mierals formed by submarine alteration of volcanic materials, whereas illite is chiefly terrigenous clastic mineral derived from the weathered rocks on the land to the north and northwest of the Mariana Trough. The distributions of these minerals show that from north to south in the Mariana Trough smectite tends to increase,while illite to decrease. FeMg chlorite does not change very much in its content. Such a distribution pattern is thought to be chieny caused by the influence of continental sources and the turbidity current flowing from east to west in the Mariana Trough. Vertically,a tendency that smectite decreases while illite increases in found mostly in the strata formed in a period from 45 ka tO 10 ka B. P.. This phenomenon is considered to be probably attributed to the influence of paleoclimatic change.