Integrated Neogene biochemostratigraphy at DSDP Site 296 on the Kyushu-Palau Ridge in the western North Pacific
Integrated Neogene biochemostratigraphy at DSDP Site 296 on the Kyushu-Palau Ridge in the western North Pacific
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北太平洋西部九州-帕劳海岭 DSDP Site 296 的综合新近纪生物化学地层学
DOI：
10.1127/nos/2019/0549
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发表时间：
2020
影响因子：
2.2
通讯作者：
Okazaki Yusuke
中科院分区：
文献类型：
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作者：
Matsui Hiroki;Horikawa Keiji;Chiyonobu Shun;Itaki Takuya;Ikehara Minoru;Kawagata Shungo;Wakaki-Uchimura Hitomi;Asahara Yoshihiro;Seki Osamu;Okazaki Yusuke
我们重新访问了深海钻探计划（DSDP）站点296的地层，这有希望作为中纬度西北太平洋的参考序列。我们构建了生物地层学（钙质超微化石，浮游有孔虫和放射虫）和化学地层学（锶同位素比，稳定的氧和碳同位素比），以揭示在过去的2000万年（百万年）在站点296连续沉积。钙质超微化石的生物地层包括NN 2-NN 21生物带（早中新世-更新世）的27个生物层，与寒武纪有孔虫和放射虫的生物层相一致。在过去的20万年不间断的沉积进一步支持锶同位素地层对准超微化石基准和相关的稳定同位素数据从底栖有孔虫与同位素汇编从太平洋。精确的年龄-深度模型显示，中新世大部分时间的沉积速率较低（< 2 cm/kyr），上新世-更新世期间的沉积速率较高（2-4 cm/kyr），并可能确定了中新世晚期至上新世早期的“生物繁盛”事件。中中新世沉积的连续性与船载生物地层学形成对比，船载生物地层学推断中中新世期间存在间断（侵蚀或非沉积）。因此，296号站点的订正地层学提供了与北太平洋其他深海站点进行对比的关键。我们的修订的年龄-深度模型提供了一个框架，为未来的研究在中新世的重要气候事件，包括中新世气候最佳，中新世中期的气候转变，和晚中新世全球冷却下的影响下，过去的黑潮。
We revisited the stratigraphy at Deep Sea Drilling Project (DSDP) Site 296, which has promise as a reference sequence for the mid-latitude western North Pacific. We constructed the biostratigraphy (calcareous nannofossils, planktic foraminifera, and radiolaria) and chemostratigraphy (strontium isotope ratios, and stable oxygen and carbon isotope ratios) to reveal continuous sedimentation at Site 296 through the past 20 million years (Myr). The biostratigraphy of calcareous nannofossils comprised 27 biohorizons from biozones NN2 to NN21 (early Miocene to Pleistocene), which are consistent with the biohorizons of planktic foraminifera and radiolaria. The uninterrupted sedimentation throughout the past 20 Myr was further supported by strontium isotope stratigraphy aligned to nannofossil datums and by correlation of stable isotope data from benthic foraminifera with an isotopic compilation from the Pacific Ocean. The refined age-depth model showed low sedimentation rates (< 2 cm/kyr) through most of the Miocene and higher sedimentation rates (2-4 cm/kyr) during the Plio-Pleistocene, and potentially identified the “biogenic bloom” event from the late Miocene to early Pliocene. The continuity of sedimentation through the middle Miocene contrasts with the shipboard biostratigraphy, which inferred a hiatus (erosion or non-deposition) during the middle Miocene. Thus, the revised stratigraphy at Site 296 provides a key to correlation with other deep-sea sites in the North Pacific. Our revised age-depth model provides a framework for future studies of important climatic events during the Miocene, including the Miocene Climatic Optimum, the middle Miocene Climatic Transition, and the late Miocene global cooling under the influence of the past Kuroshio Current.