IODP Survey of the "Shackleton Sites" on the Southwest Iberian Margin

我们对地球气候系统的理解的进步将依赖于我们将海洋，冰芯和陆地序列的高分辨率沉积档案联系起来的能力，并在新的地球系统建模方法的背景下解释这些记录。世界上很少有地方能够有足够详细和明确的海洋-冰-陆地联系。IODP和更广泛的钻探界面临的一个挑战是，从适当的地点确定和恢复海洋、冰和陆地序列，并具有足够的时间分辨率，以研究综合气候系统的过程。一个这样的区域是伊比利亚边缘西南部，在那里已经证明，表面氧同位素记录可以精确地与温度变化相关（即，d18O）。通过比较，在同一个核心的底栖d18 O信号类似于从南极洲的温度记录。此外，狭窄的大陆架和塔霍河的邻近，导致陆地物质迅速进入葡萄牙近海的深海环境，从而提供了大气变化的记录，并使海洋和冰芯记录与欧洲陆地序列相关联。这是海洋中唯一一个明确证明海洋-冰-陆地相关性的地方。因此，非常希望通过JOIDES决议（JR）的钻探来扩展伊比利亚边缘记录，以涵盖上新世-更新世冰川-间冰期旋回的全部范围。为此，由英国领导的16个支持者组成的国际小组向IODP提交了提案771-Full。科学指导和评估小组（SSEP）对该建议表示欢迎并进行了审查，但IODP现场调查小组（SSP）发现地震数据质量方面存在重大不足：“该小组对所提交数据的适当性提出了几项关切，包括对目标的适当成像和场地位置。该小组还讨论了是否需要两条高分辨率线，并认为存在大量迁移沉积物或密集断层的地方值得这两条高分辨率线。“这项提案要求25天的船期来收集满足SSP要求和建议所需的必要地震和沉积物数据。还提出了几个“独立”的科学目标，涉及现代水文和沉积过程的西南伊比利亚边缘，和校准古海洋学代理用于重建过去的变化，在深水循环。这一增值科学将有效利用船舶时间，并为解释IODP获得的底层记录提供所需的关键信息。

Advances in our understanding of the Earth's climate system will rely on our ability to link high-resolution sedimentary archives from the oceans, ice-cores and terrestrial sequences, and to interpret these records in the context of novel Earth system modeling approaches. Few places exist in the world where sufficiently detailed and unambiguous marine-ice-terrestrial linkages are possible. One challenge for IODP, and the broader drilling community in general, is to identify and recover marine, ice and terrestrial sequences from appropriate locations and with adequate temporal resolution to study processes of the integrated climate system. One such region is the southwest Iberian Margin where it has been demonstrated that the surface oxygen isotopic record could be correlated precisely to temperature variations (i.e., d18O) in Greenland ice cores. By comparison, the benthic d18O signal in the same core resembled the temperature record from Antarctica. Moreover, the narrow continental shelf and proximity of the Tagus River results in the rapid delivery of terrestrial material to the deep-sea environment off Portugal, thereby providing a record of atmospheric changes and permitting correlation of marine and ice core records to European terrestrial sequences. This is the only place in the ocean where such marine-ice-terrestrial correlations have been demonstrated unambiguously. It is therefore highly desirable to extend the Iberian Margin record to encompass the full range of Plio-Pleistocene glacial-interglacial cycles by drilling with the JOIDES Resolution (JR).Towards this end, Proposal 771-Full was submitted to IODP by an international group of 16 proponents led by the UK. The proposal was well received and reviewed by the Science Steering and Evaluation Panel (SSEP), but the IODP Site Survey Panel (SSP) identified major inadequacies in the quality of the seismic data:"The panel raised several concerns on the suitability of the submitted data with regard to its appropriateness, both to image the target properly and with regard to the site location. The panel also discussed the need for 2 high-resolution lines and considered that places where Mass Transport Deposits (MTDs) or closely spaced faults were present deserved these 2 high-resolution lines."This proposal requests 25 days of ship time to collect the necessary seismic and sediment data needed to meet the SSP requirements and recommendations. Several "stand-alone" scientific objectives are also proposed related to the modern hydrography and sedimentary processes on the southwest Iberian Margin, and calibration of palaeoceanographic proxies used for reconstructing past changes in deep-water circulation. This value-added science will make effective use of ship time and contribute key information needed to interpret the downcore records to be obtained by IODP.