A subduction influence on ocean ridge basalts outside the Pacific subduction shield.
A subduction influence on ocean ridge basalts outside the Pacific subduction shield.
复制标题
俯冲对太平洋俯冲盾构外洋脊玄武岩的影响
DOI：
10.1038/s41467-021-25027-2
复制
发表时间：
2021-08-06
影响因子：
16.6
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Yang AY;Langmuir CH;Cai Y;Michael P;Goldstein SL;Chen Z
板块构造旋回产生化学性质不同的洋中脊玄武岩和岛弧火山岩，后者富含Ba、Rb、Th、Sr和Pb等元素，但由于俯冲板块富含水的通量而贫化Nb。来自弧后盆地的具有中间成分的玄武岩表明，这种板片通量可以被输送到弧的火山前缘后面并并入地幔流中。因此，令人费解的是为什么在洋中脊玄武岩中很少发现俯冲改变的地幔熔融物。在这里，我们报告了来自北极加克尔海脊的第一个具有明显弧特征的洋中脊玄武岩样本，类似于弧后盆地玄武岩。 576 个 Gakkel 样本的新高精度数据集表明该地区存在普遍的俯冲影响。这种影响也可以在大西洋和印度洋中脊玄武岩中发现，但在太平洋洋中脊玄武岩中几乎不存在。这种半球尺度的上地幔异质性反映了软流圈地幔的俯冲改造，软流圈地幔融入了地幔流，其地理分布主要受包围太平洋180米的“俯冲盾”控制。简单的建模表明，相当于弧输出的约 13% 的板片通量被纳入对流上地幔中。
The plate tectonic cycle produces chemically distinct mid-ocean ridge basalts and arc volcanics, with the latter enriched in elements such as Ba, Rb, Th, Sr and Pb and depleted in Nb owing to the water-rich flux from the subducted slab. Basalts from back-arc basins, with intermediate compositions, show that such a slab flux can be transported behind the volcanic front of the arc and incorporated into mantle flow. Hence it is puzzling why melts of subduction-modified mantle have rarely been recognized in mid-ocean ridge basalts. Here we report the first mid-ocean ridge basalt samples with distinct arc signatures, akin to back-arc basin basalts, from the Arctic Gakkel Ridge. A new high precision dataset for 576 Gakkel samples suggests a pervasive subduction influence in this region. This influence can also be identified in Atlantic and Indian mid-ocean ridge basalts but is nearly absent in Pacific mid-ocean ridge basalts. Such a hemispheric-scale upper mantle heterogeneity reflects subduction modification of the asthenospheric mantle which is incorporated into mantle flow, and whose geographical distribution is controlled dominantly by a “subduction shield” that has surrounded the Pacific Ocean for 180 Myr. Simple modeling suggests that a slab flux equivalent to ~13% of the output at arcs is incorporated into the convecting upper mantle.
登录
查看更多内容
影响因子：
5.3
作者：
HOFMANN, AW;WHITE, WM
通讯作者：
WHITE, WM
影响因子：
5.3
作者：
DIXON, JE;STOLPER, E;DELANEY, JR
通讯作者：
DELANEY, JR
影响因子：
3.5
作者：
Gale, Allison;Dalton, Colleen A.;Schilling, Jean-Guy
通讯作者：
Schilling, Jean-Guy
影响因子：
64.8
作者：
DUPRE, B;ALLEGRE, CJ
通讯作者：
ALLEGRE, CJ
影响因子：
5.3
作者：
CHAUVEL, C;HOFMANN, AW;VIDAL, P
通讯作者：
VIDAL, P