High resolution analysis of paleoenvironment and material transport during the hot-house Earth system

该研究小组（组长：Hisatake Okada）于1999年利用科学研究补助金（第11691113号）在法国南部开始了一个实地调查和取样项目。该项目旨在对IODP（综合大洋钻探计划）的主要目标之一“极端气候下的古环境”进行初步研究。该团队对白垩纪中期暖事件的OAE1b间隔进行了广泛研究，并获得了包含Paquier间隔的大量柱状剖面，并在OAE1b井段上部进行了多次试钻。（科研资助号15253007）作为法国南部白垩纪中期OAE层序古海洋学研究的第二个项目，我们计划从OAE 1a和OAE 1b层段获得高质量岩心。我们聘请了一家专业公司FORACO来完成这项任务，并成功地从Barrem以北10公里处的Goguel（OAE1a）水平恢复了60米的岩心 ...更多信息 村庄和15米的核心从基利安（OAE1b）水平在圣安德烈。这些是从这些间隔中发现的第一批岩心。为了对这些岩心进行高质量的分析，我们开发了新技术：用特殊树脂固定整个岩心而不干扰断裂部分的技术，以及精密微钻技术，以1 mm的间隔获得样品。除了对整个岩心进行精心的非破坏性分析外，还进行了各种微古生物学、地球化学和沉积学分析。由于这些分析，现在很清楚，在OAE1a事件中黑色页岩形成期间存在两种类型的海洋条件：一种是总水柱变成缺氧的条件，导致海洋生物层的破坏，另一种是缺氧水没有到达透光层，对海洋生物群的影响有限。同样明显的是，在OAE1b事件的基利安水平期间，发生了四个缺氧波动周期。这种波动的原因可以归结为陆地养分供应量的变化引起的初级生产力水平的波动。少

This research group (Leader : Hisatake Okada) had started in 1999 a field survey and sampling project in Southern France using the Grant-in Aid for Scientific Research (No. 11691113). The project was designed as a precursory study for one of IODP (Integrated Ocean Drilling Program)'s main target, the "Paleoenvironment under Extreme Climates". The team had studied extensively the OAE1b interval of Mid-Cretaceous Warm Event, and had obtained a massive columnar section containing Paquier interval, and also had conducted several test drilling at the upper level of OAE1b interval.In this new research project (Grant-in Aid for Scientific Research No. 15253007) designed as the second project to study the paleoceanography of Mid-Cretaceous OAE sequence in Southern France, we have planed to obtain high quality cores from OAE1a and OAE 1b intervals. We have hired a professional company FORACO for this task and have succeeded to recover a 60m core from Goguel (OAE1a) level at 10km north of Barrem … More Village and also 15m cores from Killian (OAE1b) level at St.Andre. These were the first cores ever recovered from these intervals. In order to conduct high-quality analysis for these cores, we have developed new techniques : a technique to fix the whole core by a special type of resin without any disturbance of the fractured portions and a technique of precise micro drilling to obtain samples at one mm intervals.In addition to elaborate non-destructive analysis for the whole cores, various micropaleontological, geochemical and sedimentological analysis has been conducted. As a result of these analysis it is now clear that two types of oceanic conditions existed during the formation of black shales in the OAE1a event : a condition with total water column becoming anoxic resulting a devastation to marine bioshere, and the other in which anoxic water did not reached to photic zone causing a limited effect to marine biota. It is also evident that during the Killian level of OAE1b event four cycles of anoxic fluctuations occurred. The cause of this fluctuations can be deduced to fluctuation of primary production level resulted by changing amount of terrestrial nutrient supply. Less