Mineralogical and seismic properties of serpentinite of Ait Ahmane fault zone of Bou Azzer ophiolite, central Anti-Atlas of Morocco

IF 2 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Comptes Rendus Geoscience Pub Date : 2019-04-01 DOI:10.1016/j.crte.2019.01.002

Mohamed Bhilisse , Hassan Admou , Ali Aydda , Lhou Maacha

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引用次数: 3

Abstract

This paper presents the first seismic measurements of serpentinite of Bou Azzer ophiolite, central Anti-Atlas of Morocco, including seismic velocities and anisotropy. Two serpentinite samples collected from the Ait Ahmane fault zone were analyzed in order to define the mineralogical and seismic features of the natural serpentinite of the Bou Azzer ophiolite. The mineralogical features were investigated using microscopic observation and Raman spectroscopy, while the seismic features were performed using an Electron Backscatter Diffraction (EBSD) instrument. Microscopy and spectroscopy analyses confirmed that the investigated serpentinite suffers from a variable degree of serpentinization, and the antigorite is the dominant variety of serpentine minerals in the study area. The crystal preferred orientation (CPO) results show that the axis [001] of the antigorite deformation is aligned subnormal to the foliation, while the axis [010] is mostly aligned subparallel to the lineation. The seismic anisotropy results are depending on serpentine amount in the rock samples. The sample with a low serpentine amount (30%) shows lowest P- and S-wave anisotropy (Vp = 7.2% and AVs = 6.55%), while the sample with a high amount of serpentine (85%) presents highest P-wave and S-wave anisotropy (Vp = 8.6% and AVs = 11.06%). Consequently, the results indicate that seismic anisotropy increases when increasing the antigorite amount.

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摩洛哥阿特拉斯中部Bou Azzer蛇绿岩Ait Ahmane断裂带蛇纹岩的矿物学和地震性质

本文介绍了摩洛哥中部反阿特拉斯地区Bou Azzer蛇绿岩蛇纹岩的首次地震测量结果，包括地震速度和各向异性。为了确定Bou Azzer蛇绿岩中天然蛇纹岩的矿物学和地震特征，对采自Ait Ahmane断裂带的2个蛇纹岩样品进行了分析。利用显微观察和拉曼光谱研究了矿物学特征，利用电子背散射衍射(EBSD)仪器研究了地震特征。显微镜和光谱学分析证实，研究区蛇纹岩存在不同程度的蛇纹岩化，反长辉石是研究区蛇纹岩矿物的优势品种。晶体择优取向(CPO)结果表明，反长岩变形轴[001]与片理呈亚正向排列，而轴[010]则大部分与线理呈亚平行排列。地震各向异性结果取决于岩石样品中蛇纹石的数量。低蛇纹石含量(30%)样品的纵波和横波各向异性最低(Vp = 7.2%， AVs = 6.55%)，高蛇纹石含量(85%)样品的纵波和横波各向异性最高(Vp = 8.6%， AVs = 11.06%)。结果表明，随着反长岩数量的增加，地震各向异性增大。

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来源期刊

Comptes Rendus Geoscience 地学-地球科学综合

CiteScore

2.80

自引率

14.30%

发文量

审稿时长

5.9 weeks

期刊介绍： Created in 1835 by physicist François Arago, then Permanent Secretary, the journal Comptes Rendus de l''Académie des sciences allows researchers to quickly make their work known to the international scientific community. It is divided into seven titles covering the range of scientific research fields: Mathematics, Mechanics, Chemistry, Biology, Geoscience, Physics and Palevol. Each series is led by an editor-in-chief assisted by an editorial committee. Submitted articles are reviewed by two scientists with recognized competence in the field concerned. They can be notes, announcing significant new results, as well as review articles, allowing for a fine-tuning, or even proceedings of symposia and other thematic issues, under the direction of invited editors, French or foreign.