北黄海西部泥质区全新世以来沉积有机碳埋藏特征

The characteristics of sedimentary organic carbon in the mud area in the western North Yellow Sea since the Holocene

  • 摘要: 北黄海西部泥质区沉积环境稳定、沉积记录连续,是重建过去周边流域变化与黄海海洋环境信息的良好载体。目前围绕北黄海西部泥质区沉积有机碳的研究工作多局限于通过表层沉积物揭示其现代分布特征,对于该泥质区长时间尺度沉积有机碳埋藏过程与机制的研究相对薄弱。通过北黄海西部泥质区W03岩芯的总有机碳指标,重建了全新世以来北黄海西部沉积有机碳的埋藏特征,探讨了气候及海洋环境变化对北黄海西部沉积有机碳埋藏的控制机制。研究表明:海平面上升的停滞期(10.3~9.8 cal.kaBP),发育硬质黏土层,有机碳以陆源输入为主(60.7%),动荡的沉积环境导致总有机碳含量相对较低,平均含量仅为0.22%;海平面上升期(9.8~7.0 cal.kaBP),海源有机碳的贡献增加(47.7%),相对稳定的沉积环境有利于该时期有机碳的埋藏;高海平面以来(7.0 cal.kaBP至今),黄海环流体系逐渐形成,陆源有机碳输入随着东亚冬季风驱动的沿岸流强度变化发生相应的改变,海源有机碳的贡献继续增加(50.0%),总有机碳的含量升高至0.58%。北黄海西部泥质区全新世以来沉积有机碳埋藏主要受控于海平面变化和海洋环流体系的运动。

     

    Abstract: The sedimentary environment of the mud area in the western North Yellow Sea is stable, and the sedimentary record is continuous, making it an excellent proxy for reconstructing paleoenvironment of the local region and surrounding watershed. Previous researches on the sedimentary organic carbon in the mud area are limited to its modern distribution characteristics through surface sediment analysis, and works on the long-term sedimentary processes and mechanisms of organic carbon remain insufficient. Core W03 in the mud area was used to reconstruct the sedimentary environment of organic carbon since the Holocene using sedimentary total organic carbon index, and to clarify the impact of climate and oceanic environmental changes on the source and deposition of organic carbon. During the period of sea level rise stagnation (10.3~9.8 cal.kaBP), a hard clay layer was developed rich in terrestrial organic carbon (60.7%). The turbulent sedimentary environment resulted in a relatively low total organic carbon content (average of only 0.22%). During the period of sea level rising (9.8~7.0 cal.kaBP), marine-sourced organic carbon (47.7%) boomed in a relatively stable sedimentary environment, which was conducive to the burial of organic carbon. Since the high sea level period (7.0 cal.kaBP to present), the Yellow Sea circulation system has been formed gradually, and the input of terrigenous organic carbon has changed correspondingly with the change of coastal current intensity under the East Asian winter monsoon scheme. The contribution of marine organic carbon was increased continuously to 50.0%, and so did the content of total organic carbon (0.58%). Therefore, sedimentary organic carbon in the mud area since the Holocene is controlled by sea level fluctuation and the resultant ocean circulation system.

     

/

返回文章
返回