Development of a Correlated Fe-Mn Crust Stratigraphy Using Pb and Nd Isotopes and Its Application to Paleoceanographic Reconstruction in the Atlantic
Development of a Correlated Fe-Mn Crust Stratigraphy Using Pb and Nd Isotopes and Its Application to Paleoceanographic Reconstruction in the Atlantic
复制标题
利用 Pb 和 Nd 同位素建立相关铁锰地壳地层学及其在大西洋古海洋重建中的应用
DOI：
10.1029/2020pa003928
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发表时间：
2020
影响因子：
3.5
通讯作者：
Josso P
中科院分区：
文献类型：
--
作者：
Josso P
八个铁锰结壳样品跨越整个深度范围内的热带海山在东北大西洋进行了分析Pb和Nd同位素重建水团起源和混合在过去的75马。Pb同位素通过激光烧蚀多集电极电感耦合等离子体质谱仪（LA-MC-ICP-MS）测定，其能够快速产生大的、高空间分辨率的数据集。这使得有可能精确地对比不同样品之间的地层，比较同时期的地层，并根据结壳中大量的间断建立一个复合记录。Pb和Nd同位素数据显示了大西洋东北部各种海洋和大陆端元的影响。这反映了它从晚白垩世的一个受限制的孤立盆地与来自特提斯洋的流入，到一个越来越混合的大型盆地的演变，直到中新世，南大洋的标志占主导地位。较少放射性成因的Nd同位素特征表明拉布拉多海水早在17-15 Ma就影响了东北大西洋盆地，流经北方路线，如查理-吉布斯断裂带。Pb和Nd同位素突出撒哈拉风成尘输入约7马的影响越来越大，赋予一个较小的放射性漂移的二元混合北大西洋水团和河流排放从西部和中部非洲之间。这突出了风成尘输入对大洋铅和钕预算的影响，并支持在晚中新世北非干旱化的早期阶段。这个签名是叠印约3马到现在的一个强大的北大西洋深水签名开始后，北方半球冰川。
Eight ferromanganese crust samples spanning the complete depth range of Tropic Seamount in the northeast Atlantic were analyzed for Pb and Nd isotopes to reconstruct water mass origin and mixing over the last 75 Ma. Pb isotopes were determined by laser ablation multicollector inductively coupled plasma mass spectrometer (LA‐MC‐ICP‐MS), which enables the rapid production of large, high spatial resolution data sets. This makes it possible to precisely correlate stratigraphy between different samples, compare contemporaneous layers, and create a composite record given the abundance of hiatuses in crusts. Pb and Nd isotope data show the influence of various oceanic and continental end‐members in the northeast Atlantic Ocean. This reflects its evolution from a restricted, isolated basins in the Late Cretaceous with influxes from the Tethys Ocean, to an increasingly well‐mixed, large‐scale basin, with a dominant Southern Ocean signature until the Miocene. Less radiogenic Nd isotope signatures suggest Labrador Sea Water influenced the northeast Atlantic basin as early as 17–15 Ma, flowing through a northern route such as the Charlie‐Gibbs Fracture Zone. Pb and Nd isotopes highlight the increasing influence of Saharan eolian dust input about 7 Ma, imparting a less radiogenic excursion to the binary mixing between North Atlantic water masses and riverine discharge from West and Central Africa. This highlights the influence of eolian dust input on the open ocean Pb and Nd budget and supports an early stage of North African aridification in the Late Miocene. This signature is overprinted about 3 Ma to the present by a strong North Atlantic Deep Water signature following the onset of Northern Hemisphere glaciation.