Strontium, Rubidium and Neodymium isotopic composition of sediments of western Pacific marginal basins (Table 1)@en
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The Nd–Sr isotopic signature of fine-grained clastic strata from western Pacific marginal basins has been examined to test the applicability of isotopic fluctuations in basin characterization, stratigraphic correlation, and provenance determinations. Neodymium and strontium isotopic analyses were conducted on Plio–Pleistocene sediments (n = 70) from DSDP/ODP drill cores in the Sea of Japan, Shikoku Basin, and the Sulu Sea. The isotopic values from these basins demonstrate the utility of Nd–Sr isotopic signatures for both interbasinal characterization and provenance evaluation, and intrabasinal stratigraphic correlations. The isotopic signature of the Sulu Sea and the Sea of Japan fluctuates within predictable limits defined by the geology of the source area, and the signature is sensitive to changes in sediment flux from isotopically homogeneous source regions. Isotopic values in the Shikoku Basin deviate strongly from predicted isotopic values with neodymium values significantly lower than expected (epsilon-Nd (-7) to (-9) vs. predicted epsilon-Nd (-2) to (+5)). This isotopically evolved signature could not have been derived from the crustal domains on the basin margins, and requires input from a previously unrecognized source. The isotopic signature of the Shikoku Basin is interpreted to represent aeolian sediment flux into the basin from eastern Eurasia coincident with paleoclimatic change in Late Pliocene to Early Pliestocene time. […]
为验证同位素波动在盆地特征刻画、地层对比及物源判别中的适用性，本研究针对西太平洋边缘盆地细粒碎屑岩的钕-锶同位素特征（Nd–Sr isotopic signature）展开了分析。研究团队对取自日本海、四国盆地（Shikoku Basin）与苏禄海的DSDP/ODP（深海钻探计划/大洋钻探计划）钻探岩心中的70件上新世-更新世沉积物样品开展了钕与锶同位素测试分析。上述盆地的同位素测试结果表明，钕-锶同位素特征可有效应用于盆地间特征刻画、物源评价以及盆地内地层对比。苏禄海与日本海的同位素特征在由物源区地质条件限定的可预测范围内波动，且该特征对来自同位素均一物源区的沉积物通量变化具有敏感性。四国盆地的同位素数值与预测值偏差显著，其钕同位素数值远低于预期值（εNd（epsilon-Nd）值为-7至-9，而预测εNd值为-2至+5）。这种演化程度较高的同位素特征无法由盆地边缘的地壳域提供物源，其物源需来自此前未被识别的区域。研究认为，四国盆地的同位素特征代表了上新世晚期至更新世早期古气候变化阶段，欧亚大陆东部的风尘沉积物通量输入至该盆地。[…]
