The earliest mantle fabrics formed during subduction zone infancy
The earliest mantle fabrics formed during subduction zone infancy
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DOI：
10.1016/j.epsl.2013.06.031
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发表时间：
2013-09
影响因子：
5.3
通讯作者：
Y. Harigane;K. Michibayashi;T. Morishita;K. Tani;H. Dick;O. Ishizuka
中科院分区：
文献类型：
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作者：
Y. Harigane;K. Michibayashi;T. Morishita;K. Tani;H. Dick;O. Ishizuka
沿南伊豆-小笠原海沟向陆斜坡的菲律宾海板块最古老的壳幔剖面（~ 52 Ma）的哈尔兹伯尔岩保存了俯冲带婴儿期形成的地幔结构；那是在太平洋板块俯冲到菲律宾海板块下面的初始阶段。哈尔茨布尔土的原生矿物相对较新鲜，尽管它们的蛇纹石化程度较重，并表现出非等粒状的叶间织构，在橄榄石（001）[100]和Opx(100)[001]中具有晶体优先取向模式。哈尔茨伯基岩具有残余橄榄岩的特征，而与哈尔茨伯基岩在同一位置获得的暗粒岩则为俯冲开始时弧火山作用的最早阶段提供了证据。我们认为（001）[100]橄榄石模式在未成熟的弧前地幔中开始形成，并在原位大洋岛弧俯冲的初始阶段增加了板源含水流体。
Harzburgites obtained from the oldest crust–mantle section in the Philippine Sea plate (∼ 52 Ma) along the landward slope of the southern Izu–Ogasawara Trench, preserve mantle fabrics formed during the infancy of the subduction zone; that is during the initial stages of Pacific plate subduction beneath the Philippine Sea plate. The harzburgites have relatively fresh primary minerals despite of their heavy serpentinizations, and show inequigranular interlobate textures, and crystal preferred orientation patterns in olivine (001)[100] and Opx (100)[001]. The harzburgites have the characteristics of residual peridotites, whereas the dunites, obtained from the same location as the harzburgites, provide evidence for the earliest stages of arc volcanism during the inception of subduction. We propose that the (001)[100] olivine patterns began forming in immature fore-arc mantle with an increase in slab-derived hydrous fluids during the initial stages of subduction in in situ oceanic island arc.