Constraining early to middle Eocene climate evolution of the southwest Pacific and Southern Ocean
Constraining early to middle Eocene climate evolution of the southwest Pacific and Southern Ocean
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DOI：
10.1016/j.epsl.2015.11.010
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发表时间：
2016
影响因子：
5.3
通讯作者：
E. Dallanave;V. Bachtadse;E. Crouch;L. Tauxe;C. Shepherd;H. Morgans;C. Hollis;Benjamin R. Hines;S. Sugisaki
中科院分区：
文献类型：
--
作者：
E. Dallanave;V. Bachtadse;E. Crouch;L. Tauxe;C. Shepherd;H. Morgans;C. Hollis;Benjamin R. Hines;S. Sugisaki
南太平洋是古近纪早期最大的洋盆，但其沉积记录缺乏。我们提出了一个新的磁性地层记录，从海洋沉积物，出露沿着中怀帕拉河，南岛，新西兰。沿沿着45 m的地层剖面采集了用于古地磁分析的全方位样品，该剖面涵盖了C23 n至C21 n（51.5-47 Ma）的磁极性年代。这些结果与有孔虫，钙质超微化石，甲藻孢囊（dinocyst）生物地层学从三个不同的探险收集的样品沿着共680米的部分。生物地层学数据表明，相对连续的沉积作用，从下Waipawan到上Heretaungan新西兰阶段（即，较低的Ypresian低Lutetian，55.5至46马）。我们提供了第一个磁性地层学校准年龄为48.88 Ma的基础Heretaungan新西兰阶段（最新的早始新世）。为了提高该剖面气候记录与其它南大洋记录的相关性，我们对大洋钻探计划（ODP）1172站（东塔斯曼高原）和综合大洋钻探计划（IODP）U1356站（南极威尔克斯陆缘）的磁性地层学资料进行了回顾。对离散样本的古地磁研究无法证实1172号地点始新世早期有任何可靠的磁极反转。我们使用强大的磁生物年代学的一系列的dinocyst生物事件，是常见的中怀帕拉，网站1172，和网站U1356，以协助三个记录之间的相关性。一个新的综合年表提供了新的见解的性质和完整性的南部高纬度气候历史来自这些网站。
Studies of early Paleogene climate suffer from the scarcity of well-dated sedimentary records from the southern Pacific Ocean, the largest ocean basin during this time. We present a new magnetostratigraphic record from marine sediments that outcrop along the mid-Waipara River, South Island, New Zealand. Fully oriented samples for paleomagnetic analyses were collected along 45 m of stratigraphic section, which encompasses magnetic polarity Chrons from C23n to C21n (∼ 51.5–47 Ma). These results are integrated with foraminiferal, calcareous nannofossil, and dinoflagellate cyst (dinocyst) biostratigraphy from samples collected in three different expeditions along a total of∼ 80 m of section. Biostratigraphic data indicates relatively continuous sedimentation from the lower Waipawan to the upper Heretaungan New Zealand stages (ie, lower Ypresian to lower Lutetian, 55.5 to 46 Ma). We provide the first magnetostratigraphically-calibrated age of 48.88 Ma for the base of the Heretaungan New Zealand stage (latest early Eocene). To improve the correlation of the climate record in this section with other Southern Ocean records, we reviewed the magnetostratigraphy of Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau) and Integrated Ocean Drilling Program (IODP) Site U1356 (Wilkes Land Margin, Antarctica). A paleomagnetic study of discrete samples could not confirm any reliable magnetic polarity reversals in the early Eocene at Site 1172. We use the robust magneto-biochronology of a succession of dinocyst bioevents that are common to mid-Waipara, Site 1172, and Site U1356 to assist correlation between the three records. A new integrated chronology offers new insights into the nature and completeness of the southern high-latitude climate histories derived from these sites.