Can the Magmatic Conditions of the Martian Nakhlites be Discerned via Investigation of Clinopyroxene and Olivine Intracrystalline Misorientations?
Can the Magmatic Conditions of the Martian Nakhlites be Discerned via Investigation of Clinopyroxene and Olivine Intracrystalline Misorientations?
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DOI：
10.1029/2021je007082
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发表时间：
2022-04
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通讯作者：
S. Griffin;L. Daly;S. Piazolo;L. Forman;B. E. Cohen;Martin R Lee;P. Trimby;R. Baumgartner;G. Benedix;B. Hoefnagels
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作者：
S. Griffin;L. Daly;S. Piazolo;L. Forman;B. E. Cohen;Martin R Lee;P. Trimby;R. Baumgartner;G. Benedix;B. Hoefnagels
变形是一种几乎普遍存在的过程，几乎在所有自然形成的岩石中都能观察到。电子背散射衍射 (EBSD) 是一种能够从与代表性 CPO 分析（nakhlites ≥ 300 个晶体）相当的晶内取向错误中推断出滑移系统（塑性变形的一种形式）的技术。对天然样品的广泛实验室和研究已经确定了橄榄石和单斜辉石内特定滑移系统特征的优先地幔条件外在参数。根据这些已知参数，对 16 种不同的火星钠辉石陨石（21 个部分）的橄榄石和辉石（高钙单斜辉石）的晶内取向错误模式进行了分析和评估。对 nakhlite 内高变形区域和低变形区域的研究揭示了 21 个部分中 10 个部分的晶内取向错误模式发生了变化。被解释为冲击（高变形）和就位（低变形）特征，观察到的两种主要变形模式的变形模式变化表明nakhlite源陨石坑的异质采样。我们的研究结果表明，冲击变形在整个钠闪石中普遍存在，并且在解释明显较低变形区域内晶体的晶内取向错误时需要非常小心。
Deformation is a near ubiquitous process that is observed within nearly all naturally forming rocks. Electron backscatter diffraction (EBSD) is a technique that enables slip‐systems (a form of plastic deformation) to be inferred from intracrystalline misorientations at a comparable scale to the representative CPO analysis (≥300 crystals for the nakhlites). Extensive laboratory and studies on naturally occurring samples have identified preferential mantle condition extrinsic parameters for specific slip‐system signatures within olivine and clinopyroxene. Intracrystalline misorientation patterns for olivine and augite (high Ca‐clinopyroxene) for 16 different Martian nakhlite meteorites (21 sections) were analyzed and assessed against these known parameters. Investigation of high and low deformation regions within the nakhlites revealed a shift in intracrystalline misorientation patterns for 10 of the 21 sections. Interpreted as both shock (high deformations) and emplacement (low deformation) signatures, the observed variations in deformation patterns for the two main regimes of deformation indicate heterogeneous sampling of the nakhlite source crater. Our findings indicate that shock deformation is prevalent throughout the nakhlites, and that great care needs to be taken when interpreting intracrystalline misorientations of crystals within apparent lower deformation regions.