Reconstructing the provenance of siliciclastic marine sediment is important for understanding sediment pathways and constraining palaeoclimate and erosion records. However, physical fractionation of different size fractions can occur during sediment transport, potentially biasing records derived from bulk sediment. In this study, records of radiogenic Sr and Nd isotopic composition and K/Al ratio of the separated clay fraction, as well as bulk grain size, are presented, measured from deep-sea sediments recovered from International Ocean Discovery Program (IODP) Sites U1456 and U1457 in the Arabian Sea. These new records are compared with published bulk sediment records to investigate the influence of sediment transport on these proxies and to constrain provenance evolution and its relationship to climate variability since middle Miocene time. Correlations between grain size and the bulk sediment isotopic composition confirm that transport processes are influencing the bulk sediment record. This relationship, although present, is not as strong in the clay-fraction isotopic records. Heterogeneity of bulk sediment likely drives differences between bulk and clay records, thought to be largely controlled by sediment transport processes. The isotopic records reveal variations in provenance that correlate with climatic change at 8–7 Ma, as well as an increase in overall provenance variability beginning at c. 3.5 Ma, likely linked to monsoon strength and glacial–interglacial cycles. The clay-fraction records highlight the potential value of measuring proxy records from multiple size fractions to help constrain provenance records as well as investigate sediment transport and/or weathering and erosion processes recorded in deep-sea sediment archives.

中文翻译：

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印度河扇中粘土分数锶和钕同位素：对沉积物运输和物源的影响

重建硅质碎屑海洋沉积物的物源对于了解沉积物路径和约束古气候和侵蚀记录具有重要意义。然而，在沉积物运输过程中可能会发生不同尺寸部分的物理分馏，这可能会使来自散装沉积物的记录产生偏差。在这项研究中，提供了从国际海洋探索计划 (IODP) 站点 U1456 回收的深海沉积物中测量的放射性 Sr 和 Nd 同位素组成和分离粘土部分的 K/Al 比以及体积粒度的记录和 U1457 在阿拉伯海。将这些新记录与已发表的大量沉积物记录进行比较，以研究沉积物迁移对这些代理的影响，并限制物源演化及其与中新世中期以来气候变化的关系。颗粒大小和大块沉积物同位素组成之间的相关性证实了运输过程正在影响大块沉积物记录。这种关系虽然存在，但在粘土分数同位素记录中并不那么强烈。大块沉积物的异质性可能导致大块和粘土记录之间的差异，这在很大程度上受沉积物输送过程的控制。同位素记录揭示了与 8-7 Ma 的气候变化相关的物源变化，以及从 大块沉积物的异质性可能导致大块和粘土记录之间的差异，这在很大程度上受沉积物输送过程的控制。同位素记录揭示了与 8-7 Ma 的气候变化相关的物源变化，以及从 大块沉积物的异质性可能导致大块和粘土记录之间的差异，这在很大程度上受沉积物输送过程的控制。同位素记录揭示了与 8-7 Ma 的气候变化相关的物源变化，以及从C。3.5 Ma，可能与季风强度和冰期-间冰期循环有关。粘土分数记录突出了测量多种尺寸分数的代理记录的潜在价值，以帮助限制来源记录以及调查深海沉积物档案中记录的沉积物迁移和/或风化和侵蚀过程。