REU: Miocene to Recent Sedimentary Conditions on the Peruvian Margin: Apatite Formation, Fluid Circulation, and Diagenesis

秘鲁海域的磷矿主要有三种类型：(1)易碎的浅色纹层，包括小似球粒和结核；(2)以似球粒为主的磷矿砂；(3)通常颜色较深，岩化程度较高的致密结核和硬地层。在海洋钻探项目（ODP） Leg 112中回收的岩心包含所有三种磷矿类型，可以扩展该地区较老的新生代到第四纪沉积物的许多方面的现有信息。因此，本项目的主要目的是：(1)提高对地质记录中控制磷矿岩阶段性沉积的海洋学和沉积学因素的认识；(2)建立地球化学和同位素标准，以区分原始沉积环境中衍生的原生属性与修改后的属性。受地下盐水或后期埋藏成岩作用的影响，或通过沉积过程的再加工和浓缩而获得的。在大陆边缘的磷矿是一个有趣的和潜在的经济矿床。本研究将探讨这些矿床形成的控制因素。秘鲁边缘钻探岩心的沉积物将通过各种地球化学技术进行检查，以寻找气候对地层的影响以及流体流动和成岩作用的沉积后影响的线索。

Three major types of phosphorites occur off Peru: (1) friable light-colored laminae, including small peloids and nodules, (2) phosphatic sands dominated by peloids, and (3) generally darker, well lithified dense nodules and hard-grounds. The cores recovered during Ocean Drilling Project (ODP) Leg 112 contain all three phosphorite types and allow expansion of the existing information on many aspects of the older Cenozoic to Quaternary sediments of this region. Accordingly, the primary aims of this project are to (1) improve the understanding of oceanographic and sedimentologic factors which control the episodic deposition of phosphorites in the geologic record, and (2) to develop geochemical and isotopic criteria which may distinguish primary properites derived in the original depositional environment, from modified properties, those acquired by the influence of a subsurface saline brine or during later burial diagenesis, or by reworking and concentration through sedimentologic processes. %%% Phosphorites on continental margins are an interesting and potentially economical mineral deposit. This study will examine the controlling factors for the formation of these deposits. Sediments from drill cores on the Peruvian margin will be examined by a variety of geochemical techniques for clues to the climatic influences on formation as well as the post- depositional effects of fluid flow and diagenesis.