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部12个深海沉积物岩心的粘土级矿物组合表现出整个新生代系统的均匀变化。目前岩心样品中的蒙脱石在大多数情况下被认为是在海底形成的。最可能的自生半射影形成方式是火山玻璃等前体的成岩变化。在这种情况下，来自生物二氧化硅的硅一定对形成机制有贡献。斜沸石与蒙脱石的共存支持了这一假设。尽管碎屑粘土矿物如伊利石、绿泥石和高岭石倾向于在较年轻的沉积物中增加，但自生蒙脱石和闪绿沸石的形成从古近纪一直持续到中新世。在上新世期间，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显著增加。太平洋板块的西西北向运动一定在接收更多碎屑级矿物方面发挥了作用。目前岩心中裂缝的存在表明，AABW有时无法在研究区域沉积粘土大小的矿物。

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.