中文摘要：

俯冲带的碳循环不仅在维持地球表层和地球深部之间的碳平衡方面起着关键的作用，而且还和许多重要的地球深部动力学过程密切相关。热动力学数值模拟和高温高压实验的研究结果表明，俯冲大洋板片中的大多数碳酸盐能够在弧前和弧下深度幸存下来，从而进入更深的地幔中。在地幔过渡带，因为板片滞留所带来的热松弛效应将使幸存下来的碳酸盐以熔体的形式释放出去，其独特的物理化学性质使这些熔体构成了一种有效的交代组分。考虑到地幔过渡带的氧逸度特别低，那些进入未经交代地幔中的碳酸盐熔体将变得不稳定而被还原成其他形式。不过在随后地幔对流上升的过程中，这些被还原的表壳碳又会因为氧逸度在某些临界深度发生突变而氧化熔融，这也许可以解释地幔不同深度所存在的某些高导低速体和地震波各向异性等现象。作为洋壳俯冲的后续过程，陆壳的深俯冲作用也可以将表壳碳带至地幔深处，例如超高压大理岩和碳酸盐化榴辉岩的广泛产出就是最好的证明。超高压变质岩中金刚石的产出表明其构成了表壳碳在地幔深处的一种重要赋存形式，研究显示其形成过程和富碳熔体、流体的活动密切相关。虽然前人针对俯冲带的碳循环已经取得了若干研究进展，然而仍有大量的科学问题亟待解决。最后就一些关键性的问题进行了列举说明，并对未来的研究方向进行了展望。

英文摘要：

Carbon cycling in subduction zones plays a key role in balancing the carbon reservoirs between the surface and the deep Earth, and influences many significant deep geodynamical processes. Results from thermodynamic numerical modeling and experimental petrology suggest that most carbonates in subducted oceanic slabs may survive in the depth range from forearc to subarc and then be transferred into the deeper mantle. Given that subducted slabs may stagnate in the mantle transition zone, later thermal relaxation would lead those surviving carbonates to be liberated into the mantle as melts, which could act as an effective metasomatic agent due to their unique physical and chemical qualities. Because the oxygen fugacity in the mantle transition zone is low, the carbonate melts that transfer into the unmetasomatic mantle would become unstable and be reduced into other forms. During later mantle convection uprising, the reduced supracrustal carbon would induce ＂redox melting＂ at some critical depths responding to the abrupt changes of oxygen fugacity, which might explain some geophysical phenomena at different mantle depths, such as high conductive and low velocity bodies and seismic anisotropy. Following the oceanic subduction, deep continental subduction could also bring some supracrustal carbon into the deep mantle, which is best evidenced by the common occurrences of ultra-high pressure （UHP） marbles and carbonated eclogites. The occurrence of diamond in UHP rocks indicates that diamond constitutes an important host for supracrustal carbon in the deep mantle. Most studies propose that the formation of metamorphic diamond relate to the activities of carbon-rich fluids/melt. Although some achievements have been made on the carbon cycling in subduction zones, there are still many related issues to be addressed. This paper lists some key issues and predicts the future research directions in the last section.