Study of Ocean Floor Structure and Evolution by Drilling

该研究项目的目的是通过海洋钻探调查地球环境变化的历史和地球内部的地球动力学。本年度主要研究了以下四个主题：1）以巴哈马海岸钻井为基础的海平面变化和碳酸盐岩台地层序地层学研究。研究表明，海侵、加积和间断的形成与海平面变化密切相关，并验证了层序地层学在这类背景下的应用。2）探讨了加州边缘和Sanich湾高分辨率岩心中记录的气候和古海洋快速变化的记录及其原因。结果表明，这些冰芯中记录到了快速降温和升温事件，这表明冰芯和高纬度海洋揭示的类似快速事件（例如海因里希事件）具有全球范围的性质。3）胡安·德富卡海岭及其沉积部分的热液系统和矿床研究基于长期钻孔观测站（CORK）。确定了热液的排泄和补给区域，确定了循环单元的大小。4）巴巴多斯和哥斯达黎加边缘板块俯冲、增生棱柱体水文地质、构造侵蚀研究。CORK实验和随钻测井被认为是非常有用的流体流动和俯冲复合体的物理性质的研究。哥斯达黎加边缘原来是一个边界，这是占主导地位的大规模俯冲侵蚀，而不是沉积物底侵，这是钻井前的首选解释。

The purpose of this research project is to investigate the history of Earth's environmental changes and geodynamics of the Earth interior through ocean drilling. This year, the following four main themes were investigated.1) Study of sea level changes and carbonate platform sequence stratigraphy based on the drilling in the Bahama bank. The study showed that progradation, agradation and hiatus formation were closely related to sea level changes and verified the use of sequence stratigraphy in this kind of setting.2) Investigation of the records and causes of rapid climatic and paleoceanographic changes recorded in the high-resolution core samples of the California margin and Sanich Inlet. The results showed that both rapid cooling and warming events were recorded in these cores suggesting that similar rapid events revealed by ice cores and hig latidude ocean such as Heinrich Event are in global scale nature.3) Study of hydrothermal system and ore deposits in the Juan de Fuca Ridge and its sedimented part based on a long-term borehole observatory (CORK). The area of hydrothermal fluid discharge and recharge was specified and the magnitude of circulation cell was determined. This result contributed significantly to the simulation of the hydrothermal system.4) Study of plate subduction, accretionary prism hydrogeology, tectonic erosion in the Barbados and Costa Rica margins. The CORK experiment and logging while drilling was found to be extremely useful for the study of fluid flow and physical properties of the subduction complex. The Costa Rica margin turned out to be a boundary which is dominated by large-scale subduction erosion, not by sediment underplating which was preferred interpretation before drilling.