地质学
大洋地壳
大洋盆地
结壳
地幔(地质学)
下沉
地球科学
地球化学
地震学
古生物学
构造盆地
俯冲
构造学
作者
Fan Yang,Fan Yang,Xiaolong Huang,Xiaolong Huang,Yi‐Gang Xu,Yi‐Gang Xu,Le Zhang,Peng-Li He,Yu Yang,Liang Liu
出处
期刊:Geology
[Geological Society of America]
日期:2024-04-23
摘要
Additional subsidence of oceanic basins compared to the half-space cooling prediction is thought to be a dynamic response to the underlying mantle convection induced by slab sinking. Here, we identified a significantly elevated proportion (10%−20%) of recycled oceanic crust (ROC) in the source of mid-ocean-ridge basalts (MORBs) from the South China Sea (SCS), illustrating the ROC accumulation within a confined upper-mantle range, possibly as a result of the long-term surrounding subduction events. The presence of this lithological heterogeneity in the ROC leads to an increase in mantle density by 0.45%−0.90% at most, thereby contributing to the observed excessive subsidence in the SCS basin when compared to other small basins affected by dynamic topography, while open oceans experience subsidence primarily due to thermal cooling. We propose that the ROC-induced density change in the upper mantle is crucial for generating the topographic anomalies in oceanic basins influenced by subducted slabs, alongside dynamic topography caused by mantle flow.
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