期刊
EARTH AND PLANETARY SCIENCE LETTERS
卷 375, 期 -, 页码 395-407出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.epsl.2013.06.003
关键词
antigorite; seismic anisotropy; subduction; electron backscatter diffraction (EBSD); CPO; LPO
资金
- NSF [EAR0309320, EAR1119403, EAR-0607775, EAR-0745588]
- University of California, Santa Barbara
- Directorate For Geosciences
- Division Of Earth Sciences [1119403] Funding Source: National Science Foundation
We report electron backscatter diffraction (EBSD) measurements of antigorite crystal preferred orientations (CPOs) from 7 samples of antigorite schist from serpentinite melanges adjacent to the Motagua fault system in central Guatemala. The CPOs range from diffuse girdle to point distributions of (001)(atg). Girdle distributions of (001)(atg), are not expected from deformation theory or experiments, suggesting that they are a result of growth rather than deformation, and may thus be topotactically related to the CPO of the olivine from which the antigorite grew. The calculated seismic anisotropy ranges from 6% to 28% in V-p, and 5% to 33% in V-s, and is highest for samples with a point maximum of (001)(atg). For all samples the minimum V-p corresponds to the pole to (001)(atg), and the maximum V-p occurs within the foliation for samples with a clearly defined foliation. Trench-parallel shear-wave splitting observations for subduction zones can best be explained by a combination of olivine B-type CPO and antigorite oriented with (001) parallel to the foliation; only a relatively thin (similar to 20 km) zone of hydrated mantle is required to explain the observed splitting times. (C) 2013 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据