Cenozoic sedimentation and clay mineralogy in the northern part of the Magellan Trough in the Central Pacific Basin

中太平洋麦哲伦海槽北方12个深海沉积岩芯中粘土矿物组合在新生代表现出系统性和均一性的变化。在大多数情况下，本岩心样品中的蒙皂石被认为是在海底原位形成的。自生火山岩的最可能形成方式是火山玻璃等前体的成岩变化。在这种情况下，来自生物硅的硅必须有助于形成的机制。斜发沸石与蒙皂石的共存支持了这一假说。自生蒙皂石和斜发沸石的形成一直持续到古近纪和中新世，尽管碎屑粘土矿物如伊利石、高岭石和高岭石倾向于在较年轻的沉积物中增加。由于全球气候变化，这些碎屑粘土大小的矿物通过空气流入研究的数量在上新世期间显著增加。太平洋板块的北西西向运动，对接收更多的碎屑类矿物起了一定作用。在目前的核心中存在的间断表明，AABW是无法存款粘土大小的矿物在研究区域的时间。

The clay-sized mineral assemblage in twelve deep-sea sediment cores from the northern part of the Magellan Trough in the Central Pacific shows systematic and homogenous changes throughout the Cenozoic. Smectite in the present core samples is considered to have been formed in sit-subsea in most cases. The most probable mode of formation of the authigenic smective was the diagenetic change of a precurosor such as volcanic glass. In this case, Si derived from biogenic silica must have contributed to the mechanism of the formation. The coexistence of clinoptilolite with smectite supports this hypothesis. The formation of authigenic smectite and dinoptilolite continued through the Paleogene and into the Miocene, even though clastic clay minerals such as illite, chlorite, and kaolinite tend to increase in younger sediments. The inflow of these clastic clay-sized minerals by air to the study remarably increased during the Pliocene owing to global climatic change. The WNW movement of the Pacific plate must have playd a role in receiving more clastic cla-sized minerals. The presence of hiatuses in the present cores suggests that AABW was unable to deposit clay-sized minerals at times in the study area.