Carbon isotope cycle and mantle structure -: art. no. L05603
Carbon isotope cycle and mantle structure -: art. no. L05603
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DOI：
10.1029/2003gl018873
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发表时间：
2004-03-04
影响因子：
5.2
通讯作者：
Lécuyer, C
中科院分区：
文献类型：
--
作者：
Coltice, N;Simon, L;Lécuyer, C
尽管沉积物和上地幔岩石的δ (13)C在地球历史上没有观察到变化，但碳同位素循环可能不是处于稳定状态。上地幔δ (13)C为- 5ppm，与俯冲碳的δ (13)C接近- 1ppm不同。事实上，大部分俯冲碳是由碳酸盐组成的：85%的俯冲沉积碳加上海洋地壳低温热液蚀变形成的碳酸盐。由于没有观测到地幔和沉积岩的长期演化，重碳的净俯冲通量需要由深部地幔过程来补偿。Gyr尺度碳同位素旋回的端元模型表明，它可能是来自深部原始储层的通量，也可能是俯冲洋壳在核幔边界的分离作用。
Despite that no change is observed in the delta(13)C of sediments and upper mantle rocks over the Earth's history, the carbon isotope cycle is probably not at steady state. The delta(13)C of - 5parts per thousand of the upper mantle is different from that of the subducted carbon, which is close to -1parts per thousand. Indeed, most of the subducted carbon is made of carbonates: 85% of subducted sedimentary carbon plus carbonates formed by low temperature hydrothermal alteration of oceanic crust. Since no long term evolution is observed for the mantle and sedimentary rocks, the net subduction flux of heavy carbon requires to be compensated by a deep mantle process. End-member models for the carbon isotope cycle at the Gyr scale suggest that it could be a flux from a deep primitive reservoir or the segregation of subducted oceanic crust at the core-mantle boundary.