Sr-Nd isotopic geochemistry of Holocene sediments from the South Yellow Sea: Implications for provenance and monsoon variability
Sr-Nd isotopic geochemistry of Holocene sediments from the South Yellow Sea: Implications for provenance and monsoon variability
复制标题
南黄海全新世沉积物的锶钕同位素地球化学：对物源和季风变化的影响
DOI：
10.1016/j.chemgeo.2017.12.033
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发表时间：
2018-02-20
期刊：
影响因子：
3.9
通讯作者：
Wei, Gangjian
中科院分区：
文献类型：
--
作者：
Hu, Bangqi;Li, Jun;Wei, Gangjian
利用元素地球化学和Sr-Nd同位素特征分析了南黄海全新世陆源沉积物的物源和搬运机制。中国和朝鲜河流沉积物的Sr-87/Sr-86比值相互重叠，而朝鲜河流沉积物的epsilon Nd值与长江和黄河相比，放射性成因普遍较低。此外，这两条大河的eNd值在全新世期间不受矿物分选的影响，相对稳定。我们提出了一个三端元（即长江、黄河和朝鲜河）混合模型来解释中黄海泥（CYSM）的沉积物物源。混合计算结果表明，黄河在大约8 ka之前是CYSM的主要沉积物来源，而长江在大约8 ka之后成为主要的沉积物来源。CYSM全新世河流输沙量的变化与海洋环流、季风气候和流域变化密切相关。在考察了解释YSC-1岩芯Sr-87/Sr-86比值在近8 kyr期间变化的几种假设后，我们初步将其归因于长江流域侵蚀模式的变化。这又与上游（印度夏季风）和中下游（东亚夏季风）季风降水的非同步演变有关。因此，我们的研究结果强调了季风气候对长江流域侵蚀模式在千年时间尺度上的显著影响。
Elemental geochemical and Sr-Nd isotopic signatures are used to decipher terrigenous sediments provenances and transport mechanisms in the South Yellow Sea during the Holocene. Sr-87/Sr-86 ratios in the Chinese and Korean riverine sediments overlap each other, whereas epsilon Nd values of Korean riverine sediments are generally less radiogenic in comparison to the Changjiang and Huanghe. Moreover, eNd values of these two large rivers appear unaffected by mineral sorting and are relative stable during the Holocene. We propose a three end-members (i.e., the Changjiang, the Huanghe, and Korean rivers) mixing model to explain sediment provenances in the Central Yellow Sea Mud (CYSM). Mixing calculations show that the Huanghe is the major sediment contributor to the CYSM before similar to 8 ka (thousand years before 1950 CE), whereas the Changjiang has become the predominant sediment source after similar to 8 ka. Holocene changes in riverine sediment supplies to the CYSM are closely related to the oceanic circulation, monsoon climate, and drainage changes. After examining several hypotheses to explain the variations in Sr-87/Sr-86 ratios of Core YSC-1 during the past similar to 8 kyr, we tentatively attribute that to changes in the erosion patterns of the Changjiang Basin. This in turn is associated with the asynchronous evolution of monsoon precipitation in the upper (Indian Summer Monsoon) and middle-lower Changjiang (East Asian Summer Monsoon). Therefore, our results highlight significant influences of monsoon climate on erosion patterns within the Changjiang catchment at millennial timescales.