Data report: Pleistocene planktonic foraminiferal oxygen and carbon stable isotope records and their use to improve the age model of Hole U1436C cores recovered east of the Aogashima Volcano
Data report: Pleistocene planktonic foraminiferal oxygen and carbon stable isotope records and their use to improve the age model of Hole U1436C cores recovered east of the Aogashima Volcano
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数据报告：更新世浮游有孔虫氧和碳稳定同位素记录及其用于改进在青岛火山东部发现的 U1436C 孔岩心年龄模型的用途
DOI：
10.14379/iodp.proc.350.201.2016
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发表时间：
2015
影响因子：
3.5
通讯作者：
M. Vautravers
中科院分区：
文献类型：
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作者：
M. Vautravers
国际海洋发现计划（IODP） 350考察队在伊豆弧前盆地西部的中等水深（海平面以下1776米）处（弧前火山aoogashima以东约60公里）采集了U1436地点。U1436位于Ocean Drilling Program Site 792 （Leg 126）以西1.5公里处。场地U1436（拟建场地IBM-4）被设想为一个150米深的岩土工程测试孔，用于未来与D/V Chikyu进行深度钻探（海底以下5500米），提供了更新世火山活动的丰富记录。这里报告的同位素地层学数据延长了时间尺度，提高了船上确定的生物地层学的精度，从而加强了对该地点记录的火山爆发的性质、起源和节奏的进一步研究。对U1436C孔70 m长的浮游有孔虫（Neogloboquadrina duterte）样品的δ18O和δ13C值进行了测量。167个样品的同位素比率被确定，并与远征350期间获得的纳米化石和浮游有孔虫数据一起进行了检查。这些数据可以相当好地确定过去1世纪以来所有的海洋同位素阶段。该数据报告的结果提供了一个精确的年龄尺度，这将增强该地点对火山学家和沉积学家的科学吸引力，并增加他们在后期研究阶段的解释的潜在影响。U1436C孔在北太平洋黑潮附近取芯，任何新的古海洋学和古气候学资料都将有价值。此外，本研究的精细地层格架也清楚地表明，远征350的最初目标可以很容易地扩展到研究地壳演化之外，转向关注地球表面过程的新目标。在国际海洋探索计划（IODP）的第350次探险中，R/V JOIDES Resolution号在西太平洋（菲律宾海）的中等水深处对两个地点进行了取样。这次考察的主要重点是IODP U1437遗址，将利用从海底以下1800米（mbsf）的间隔中恢复的随时间变化的火山作用的沉积记录，研究过去10年的弧后演化。相比之下，IODP Site U1436最初被认为是一个辅助目标，因为它的目的是作为一个短（150米）的地质工程孔，为未来使用D/V Chikyu在IBM-4的潜在钻井做准备，该钻井能力钻到5500 mbsf的弧形中地壳目标。尽管如此，U1436遗址获得了受弧前爆炸性火山作用影响的晚更新世弧前沉积物的潜在连续记录。因此，这个地点提供了一个机会，可以在一个相当近的位置（即在aoogashima火山岛附近）（图F1）调查伊豆弧内晚更新世火山活动的详细历史和演变。一旦钻井不得不在U1437站点停止，并且制定了应急计划，这个额外的目标就变得特别有吸引力。事实上，这一改变意味着U1436站点可以通过多个孔进行取心，以提高整个剖面的质量（即，较少的段段因取心干扰而损失），特别是在含有明显厚的黑色玻璃基性灰层的段段。根据U1436A孔建立的年龄模型，估计该层的初步年龄约为0.75 Ma。U1436井的岩心采收率非常好，尤其是U1436C井，70米岩心采收率达到100%。由于samM.J的时间有限，本研究中使用的样品全部取自U1436C孔。沃特拉弗斯等。资料报告：更新世浮游有孔虫同位素记录的提取，是在350考察之后，在IODP 351考察开始时进行的，因为没有复合剖面，而且U1436C孔的取芯主要使用半长超前活塞盖（HLAPC），因此比U1436A孔的取芯受到的干扰要小得多。在采集之前对样品进行的快速评估显示，通常用于稳定同位素研究的底栖有孔虫物种丰度低，并且在岩心下部不连续出现（例如，杀虫或蛭形虫）。因此，选择了一种浮游有孔虫代替。在这样一个亚热带站点（~32°N；图F1）和黑潮附近，热斜井物种Neogloboquadrina dutertrei（见图F2的插图）最有可能保存完好，并且在整个剖面中以一个单一的、狭窄的尺寸片段足够丰富，从而能够为上更新世站点提供连续的同位素记录。众所周知，海洋方解石中的氧同位素，特别是有孔虫试验中的氧同位素，提供了冰期-间冰期旋回的良好记录。他们通过综合记录当地水温变化（Emiliani, 1955）和海洋δ18O组成的全球变化（由于冰量的变化而随时间变化）的影响来捕获水的δ18O组成（Shackleton, 1967）。在需要连续记录（即不遗漏旋回）的限制下，δ18O所显示的规则和旋回模式及其全球性质使其成为地层对比和非绝对测年的经典（即常规用于~50 y）和直接工具。对于新近纪（即最后23.5 m）尤其如此（Gradstein et al., 2012）， δ18O提供了非常准确的记录。我们将U1436C孔的氧同位素记录与堆积的底栖生物δ18O记录进行了视觉关联，即所谓的LR04（图F3B），该记录的分辨率为~1 ky，由Lisiecki和Raymo（2005）对57个海洋站点的底栖生物δ18O数据进行汇编而成。这使我们能够将新获得的稳定同位素记录从深度尺度转移到年龄尺度，并建立比仅通过生物地层学获得的更详细和精确的地层学（参见Expedition 350方法章节[Tamura et al., 2015]）。图F1。远征350孔U1436C和海洋钻探计划（ODP） 126腿地点792,786和787的位置。U1436位于aoogashima以东60公里处，aoogashima是一座弧形的火山，形成了一个有人居住的小岛。这张图略微修改自Expedition 350总结章节（Tamura et al., 2015b）。
International Ocean Discovery Program (IODP) Expedition 350 cored Site U1436 at intermediate water depth (1776 meters below sea level) in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano, Aogashima. Site U1436 lies 1.5 km west of Ocean Drilling Program Site 792 (Leg 126). Site U1436 (proposed Site IBM-4), conceived as a 150 m deep geotechnical test hole for future deep drilling (5500 meters below seafloor) with the D/V Chikyu, provides a rich record of Pleistocene volcanism. Isotopic stratigraphy data reported here extend the timescale and improve the precision of the shipboard-determined biostratigraphy to enhance further investigations on the nature, origin, and rhythm of the volcanic eruptions recorded at this site. The δ18O and δ13C values in selected samples containing planktonic foraminifers (Neogloboquadrina dutertrei) were measured over the 70 m long record from Hole U1436C. Isotopic ratios were determined for 167 samples and are examined in conjunction with nannofossil and planktonic foraminifer datums obtained during Expedition 350. These data allow fairly good identification of all marine isotope stages over the last 1 My. The results from this data report provide a refined age scale that will enhance the scientific appeal of this site to volcanologists and sedimentologists and increase the potential impact of their interpretations in later research stages. Hole U1436C was cored near the Kuroshio Current in the North Pacific Ocean realm, where any new paleoceanographic and paleoclimatologic data would be valuable. Furthermore, the refined stratigraphic framework from this study also clearly shows that the original goals of Expedition 350 can easily be expanded beyond that of the study of the evolution of the Earth’s crust toward new targets focused on Earth surface processes. Introduction During International Ocean Discovery Program (IODP) Expedition 350 on board the R/V JOIDES Resolution, two sites were cored at intermediate water depth in the western Pacific Ocean (Philippine Sea). The main focus of the expedition was IODP Site U1437, at which rear-arc evolution over the last 10 My will be studied using the sedimentary record of changing volcanism through time recovered from an interval extending to 1800 meters below seafloor (mbsf). In contrast, IODP Site U1436 was initially thought of as an ancillary target because it was intended as a short (150 m) geotechnical hole to prepare for potential future drilling at proposed Site IBM-4 using the D/V Chikyu, which has the capacity to drill to the arc middle crust target at 5500 mbsf. Nonetheless, Site U1436 yielded a potentially continuous record of Late Pleistocene fore-arc sediments influenced by arc-front explosive volcanism. This site, therefore, provides an opportunity to investigate in a rather proximal location (i.e., near the volcanic island of Aogashima) (Figure F1) the detailed history and evolution of Late Pleistocene volcanism within the Izu arc. This additional goal became particularly appealing once drilling had to be stopped at Site U1437 and a contingency plan was put in place. Indeed, this change meant that Site U1436 could be cored through more than one hole to improve the quality of the entire section (i.e., with fewer intervals lost to coring disturbance) as well as more particularly in an interval containing a conspicuously thick black glassy mafic ash layer. The preliminary age for this layer, based on the age model constructed for Hole U1436A, was estimated to be about 0.75 Ma. Core recovery at Site U1436 was excellent, particularly in Hole U1436C, with 100% recovery for the 70 m cored. The samples used in this study were taken exclusively from Hole U1436C because of the limited time available for samM.J. Vautravers et al. Data report: Pleistocene planktonic foraminiferal isotope records pling, which was conducted after Expedition 350 during the transit at the start of IODP Expedition 351, because of the absence of a composite section, and because Hole U1436C was mostly cored using the half-length advanced piston corer (HLAPC) and is consequently much less disturbed than cores from Hole U1436A. A quick assessment of the samples prior to picking revealed low abundances and discontinuous downcore occurrences of benthic foraminiferal species commonly used for stable isotope studies (e.g., Cibicides or Uvigerina). Therefore, one planktonic foraminifer species was chosen instead. At such a subtropical site (~32°N; Figure F1) and in the vicinity of the Kuroshio Current, the thermoclinedwelling species Neogloboquadrina dutertrei (see inset image in Figure F2 for illustration) has the best likelihood to be both well preserved and abundant enough in one single, narrow size fraction throughout the whole section to be able to provide a continuous isotope record for the site over the Upper Pleistocene. It is well established that oxygen isotopes in marine calcite, in particular in foraminifer tests, provide an excellent record of glacial–interglacial cycles. They capture the water δ18O composition through a composite recording of the effects of local water temperature changes (Emiliani, 1955) and global changes in ocean δ18O composition, which varies through time as a consequence of changing ice volume (Shackleton, 1967). Within the limitation imposed by the need for continuous recording (i.e., no missing cycles), the regular and cyclic pattern shown by δ18O and its global nature makes it now a classic (i.e., used routinely for ~50 y) and straightforward tool for stratigraphic correlation and nonabsolute dating. This is particularly true for the Neogene (i.e., the last 23.5 My) (Gradstein et al., 2012), over which δ18O provides a highly accurate record. We visually correlated our oxygen isotope record from Hole U1436C to a stacked δ18O benthic record, the so-called LR04 (Figure F3B), which has a resolution of ~1 ky and was developed from the compilation of the benthic δ18O data from 57 marine sites by Lisiecki and Raymo (2005). This allowed us to transfer our newly obtained stable isotope record from its depth scale to an age scale and establish a more detailed and precise stratigraphy than that obtained via biostratigraphy only (see the Expedition 350 methods chapter [Tamura et al., 2015a]). Figure F1. Location of Expedition 350 Hole U1436C and Ocean Drilling Program (ODP) Leg 126 Sites 792, 786, and 787. Site U1436 lies 60 km east of Aogashima, an arc-front mafic volcano that forms a small and inhabited island. Figure was slightly modified from the Expedition 350 summary chapter (Tamura et al., 2015b).
过去 75 ka 西南极半岛漂移沉积物的古环境记录
DOI：
10.1144/sp381.12
发表时间：
2013
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
Vautravers M
通讯作者：
Vautravers M