Petrogenesis of axial lavas from the southern Chile ridge : Major element constraints
Petrogenesis of axial lavas from the southern Chile ridge : Major element constraints
复制标题
智利南部海脊轴向熔岩的岩石成因：主要元素限制
DOI：
10.1029/97jb00510
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发表时间：
1997
影响因子：
--
通讯作者：
E. Klein
中科院分区：
文献类型：
--
作者：
S. Sherman;J. Karsten;E. Klein
我们提出了主要元素玻璃数据163个岩石样品收集的四个脊段智利南部脊之间的奇洛埃断裂带和智利边缘三重连接，包括目前正在俯冲的智利海沟（段1）。海岭下地幔在小的空间尺度上是不均匀的。正常的洋中脊玄武岩（N-MORB），从所有四个脊段恢复，经历了不同程度的低压分馏，但已产生的相对均匀的范围（F）和初始压力（PO）的熔融略有不均匀的亏损源。1型E-MORB，只发现在第4段，微量元素的亲和力，一些洋岛玄武岩，显示大范围的常量和高MgO的主要元素的变化，并在空间上与N-MORB。2型E-MORB与俯冲带背景有微量元素的密切关系。它们被发现在两个第1节网站和沿着大部分的第3节。为了最小化分馏和源异质性效应并评估熔融条件，E-MORB组合物被双重回溯至8wt% MgO和0.1的K/Ti比。虽然F和PO的大小是依赖于模型的，我们发现，N-MORB和两种类型的E-MORB在相似的熔化条件下产生。这些观测结果表明，扩张速率和地幔温度施加主要控制南部智利海脊热制度。我们看到没有影响的主要元素系统学和熔融条件的最接近的海沟部分的脊俯冲。
We present major element glass data for 163 rock samples collected from four ridge segments of the southern Chile Ridge between the Chiloe Fracture Zone and the Chile Margin Triple Junction, including the segment currently being subducted at the Chile Trench (segment 1). The subridge mantle is heterogeneous at small spatial scales. Normal mid-ocean ridge basalts (N-MORB), recovered from all four ridge segments, have experienced variable extents of low pressure fractionation but have been generated by relatively uniform extents (F) and initial pressures (Po) of melting of a slightly heterogeneous depleted source. Type 1 E-MORB, found only on segment 4, have trace element affinities to some ocean island basalts, display a large range of major element variations at constant and high MgO, and are spatially associated with N-MORB. Type 2 E-MORB have trace element affinities with suprasubduction zone settings. They are found at two segment 1 sites and along most of segment 3. In order to minimize fractionation and source heterogeneity effects and assess melting conditions, E-MORB compositions were double-backtracked to 8 wt % MgO and a K/Ti ratio of 0.1. Although the magnitudes of F and Po are model-dependent, we find that N-MORB and both types of E-MORB were generated under similar melting conditions. These observations indicate that spreading rate and mantle temperature exert primary control on the southern Chile Ridge thermal regime. We see no influence of ridge subduction on the major element systematics and melting conditions of segments closest to the trench.
影响因子：
3.9
作者：
MCKENZIE, D;BICKLE, MJ
通讯作者：
BICKLE, MJ