International Ocean Discovery Program Expedition 371 Preliminary Report : Tasman frontier subduction initiation and paleogene climate-猫眼课题宝

DOI：

10.14379/iodp.pr.371.2018

发表时间：

2018

期刊：

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其他

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作者：

R. Sutherland;G. Dickens;P. Blum;C. Agnini;L. Alegret;J. Bhattacharya;A. Bordenave;Liao Chang;J. Collot;M. Cramwinckel;E. Dallanave;M. Drake;S. Etienne;M. Giorgioni;M. Gurnis;D. Harper;H. Huang;A. Keller;A. Lam;He Li;H. Matsui;C. Newsam;Y. Park;K. Pascher;S. Pekar;D. Penman;S. Saito;W. Stratford;T. Westerhold;Xiaoli Zhou

2017年7月27日至9月26日，国际海洋发现计划（IODP） 371考察队在西南太平洋塔斯曼海钻探了六个地点。主要目的是通过恢复古近系沉积记录来了解汤加-克马德克俯冲的起始。次要目标包括了解古近纪以来的区域海洋学和气候。在58天的总考察时间中，在36.4天的现场钻探中，共钻探了6个地点，回收了2506 m的岩心沉积物和火山岩。在两个地点收集了电缆日志。由于只有深海钻井项目206、207和208在该地区的始新世上部地层中进行了钻探，因此使用岩心和测井资料进行的船载观测代表了对西兰迪亚北部基础知识的重大收获。U1506-U1510五个测点的岩心层段取样了纳米化石和有孔虫软泥或白垩，其中含有粘土含量变化的火山或火山碎屑层段。古新世和白垩纪剖面从富含粘土到主要是粘土岩。在最后一个地点（U1511），发现了一系列深海粘土和硅藻土，其中只有少量的碳酸盐。每个地点底部的地层年龄都在始新世中期到晚白垩世之间，我们的新结果为定义正式的岩石地层单位提供了第一个坚实的基础，这些单位可以在西兰迪亚北部的大部分地区进行测绘，并与新喀里多尼亚和新西兰的陆上地区有关。371考察队回收的材料和数据使主要的科学目标得以实现。所有6个地点都提供了新的地层和古地理信息，这些信息可以通过区域地震地层解释与背景联系起来，从而为俯冲带起源的地球动力学模型提供了强有力的约束。我们的新观测结果可以与板块变形的时间、垂直运动的大小和时间、火山活动的时间和类型直接相关。次生古气候目标虽未全部按计划完成，但获得了重要的西南太平洋气候新记录。

International Ocean Discovery Program (IODP) Expedition 371 drilled six sites in the Tasman Sea of the southwest Pacific between 27 July and 26 September 2017. The primary goal was to understand Tonga-Kermadec subduction initiation through recovery of Paleogene sediment records. Secondary goals involved understanding regional oceanography and climate since the Paleogene. Six sites were drilled, recovering 2506 m of cored sediment and volcanic rock in 36.4 days of on-site drilling during a total expedition length of 58 days. Wireline logs were collected at two sites. Shipboard observations made using cores and logs represent a substantial gain in fundamental knowledge about northern Zealandia, because only Deep Sea Drilling Project Sites 206, 207, and 208 had penetrated beneath upper Eocene strata within the region. The cored intervals at five sites (U1506-U1510) sampled nannofossil and foraminiferal ooze or chalk that contained volcanic or volcaniclastic intervals with variable clay content. Paleocene and Cretaceous sections range from more clay rich to predominantly claystone. At the final site (U1511), a sequence of abyssal clay and diatomite was recovered with only minor amounts of carbonate. The ages of strata at the base of each site were middle Eocene to Late Cretaceous, and our new results provide the first firm basis for defining formal lithostratigraphic units that can be mapped across a substantial part of northern Zealandia and related to onshore regions of New Caledonia and New Zealand. The material and data recovered during Expedition 371 enable primary scientific goals to be accomplished. All six sites provided new stratigraphic and paleogeographic information that can be put into context through regional seismic-stratigraphic interpretation and hence provide strong constraints on geodynamic models of subduction zone initiation. Our new observations can be directly related to the timing of plate deformation, the magnitude and timing of vertical motions, and the timing and type of volcanism. Secondary paleoclimate objectives were not all completed as planned, but significant new records of southwest Pacific climate were obtained.

International Ocean Discovery Program Expedition 371 Preliminary Report : Tasman frontier subduction initiation and paleogene climate

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