Site Surveys für IODP-Bohrungen im subtropischen Nordatlantik (Koordination der MARIA S. MERIAN Reise 11)

玛丽亚S. MERIAN Cruise MSM 11由两条航线组成，前往亚热带北大西洋。第一段航程的目的是调查北纬23 '处大西洋中脊西侧的北池沉积盆地。第二航段的主要目标是对Afnca西北部外的大陆坡进行地震勘测和沉积地质调查。这两条腿都致力于准备IODP钻探考察。北池是位于大西洋中脊西侧的一个孤立的沉积物池，为研究深埋沉积物和下伏基底中的微生物群落及其活动提供了机会。选择北池的一个重要理由是，北池的地球化学、水文和地质背景先前已通过一系列DSDP和ODP钻探孔和海底观测站进行了研究。然而，现有的现场勘测数据不足以满足计划在2010财年之前进行的经批准的北池lODP钻探考察。因此，对MSM 11/1进行拟议调查的目标是以详细的方式绘制北池，以便能够精确定位计划的1 ODP孔。这些调查包括北池沉积物-基底界面的详细地震绘图、额外的热流数据以及沉积物的地球化学和微生物取样。此外，对北池周围的上地壳进行疏浚，将有助于更好地确定北池的岩石学背景。拟议的MERIAN巡航考察以及计划中的1 ODP钻探项目将为深层生物圈研究提供独特的综合地球物理、（生物）地球化学和微生物数据集。拟议的MSM 11/2的主要议题是筹备一次题为“西北非洲大陆边缘新近纪古气候和沉积物迁移”的1 ODP考察。在加那利群岛东南部的Cap Bojador与塞内加尔河和冈比亚河的三角洲之间，我们打算收集五个不同地区的地震数据作为现场前调查。10个站点中的4个站点应至少覆盖最近10至15 Ma，以重建Afncan季风的新近纪发展并记录北非大陆上新世早期的干旱化。另外6个地点应勘探高蓄积区的沉积物，以便对亚热带的快速气候变化和相关的沉积物迁移进行高分辨率研究。拟议巡航的另一个主题将是调查Cap Blanc外的粒子传输和特性。将更新CB站（自1988年以来）和CBi站（自2002年以来）沉积物收集器、海洋学和光学传感器的长期系泊设备。在水柱和沉积物表面的颗粒的额外样本将！通过水取样器、现场泵和多芯取样器采集。

MARIA S. MERIAN Cruise MSM 11 comprises two legs to the subtropical North Atlantic. Aim of the first leg is to investigate the North Pond sedimentary basin at the western flank of the Mid Atlantic Ridge at 23'N. Main objectives of the second leg are the seismic survey and sediment geology investigations ofthe continental slope off NW Afnca. Both legs are dedicated to the preparation of lODP drilling expeditions. North Pond, an isolated sediment pond located on the Western flank ofthe mid-Atlantic Ridge, offers the opportunity to study microbial communities and their activities in deeply-buried sediments and the underlying basement. One important argument for choosing North Pond is that the geochemistry, hydrology, and geologic setting of North Pond have been previously studied by a series of DSDP and ODP dnil holes and seafloor observatories. However the existing site survey data are not sufficient for the approved North Pond lODP drilling expedition, scheduled to take place not before FY 2010. The goal ofthe proposed investigations on MSM 11/1 is therefore to map North pond in a detailed way in order to be able to position planned lODP holes precisely. These surveys compromise a detailed seismic mapping of the sediment-basement interface of North Pond, additional heat flow data and geochemical and microbial sampling of the sediments. In addition dredging of the upper crust, surrounding North Pond, will help to better define the petrological setting of North Pond. The proposed MERIAN cruise together with the planned lODP drilling project will provide a unique comprehensive geophysical, (bio)geochemical and microbial data set for the study of the deep biosphere. Main topic of the proposed MSM 11/2 is the preparation of an lODP expedition entitled Neogene Paleoclimate and sediment transport at the continental margin of NW Africa. Between Cap Bojador, southeast of the Canary Islands, and the deltas of rivers Senegal and Gambia we intend to collect seismic data in five different areas as presite survey. 4 out of 10 sites should cover at least the last 10 to 15 Ma to reconstruct the Neogene development of the Afncan monsoon and to document the early Pliocene aridification of the north African continent. Further 6 sites should explore sediments in high accumulation areas for a high resolution study of rapid climate changes in the subtropics and related sediment transport. Another topic of the proposed cruise will be the investigation of particle transport and charactenstics off Cap Blanc. Longterm moorings of sediment traps, oceanographic and optical sensors at stations CB (since 1988) and CBi (since 2002) will be renewed. Additional samples of particles in the water column and at the sediment surface wil! be taken by water samplers, in-situ pumps, and multicorers.