Institute of Geoscience, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, 07745, Jena, Germany.
Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
Nat Commun. 2023 Feb 4;14(1):606. doi: 10.1038/s41467-023-36320-7.
When affected by impact, quartz (SiO) undergoes an abrupt transformation to glass lamellae, the planar deformation features (PDFs). This shock effect is the most reliable indicator of impacts and is decisive in identifying catastrophic collisions in the Earth´s record such as the Chicxulub impact. Despite the significance of PDFs, there is still no consensus how they form. Here, we present time-resolved in-situ synchroton X-ray diffraction data of single-crystal quartz rapidly compressed in a dynamic diamond anvil cell. These experiments provide evidence for the transformation of quartz at pressures above 15 GPa to lamellae of a metastable rosiaite (PbSbO)-type high-pressure phase with octahedrally coordinated silicon. This phase collapses during decompression to amorphous lamellae, which closely resemble PDFs in naturally shocked quartz. The identification of rosiaite-structured silica provides thus an explanation for lamellar amorphization of quartz. Furthermore, it suggests that the mixed phase region of the Hugoniot curve may be related to the progressive formation of rosiaite-structured silica.
当受到冲击影响时，石英（SiO）会突然转变为玻璃薄片，即面内变形特征（PDFs）。这种冲击效应是冲击的最可靠指示，对于确定地球记录中的灾难性碰撞（如希克苏鲁伯撞击）具有决定性作用。尽管 PDFs 意义重大，但它们的形成方式仍存在争议。在这里，我们展示了在动态金刚石压腔中快速压缩的单晶石英的时间分辨原位同步辐射 X 射线衍射数据。这些实验为石英在压力高于 15GPa 时转变为具有八配位硅的亚稳罗息盐（PbSbO）型高压相的薄片提供了证据。这种相在减压过程中坍塌为非晶薄片，与自然冲击石英中的 PDFs 非常相似。因此，罗息盐结构二氧化硅的鉴定为石英的层状非晶化提供了一种解释。此外，它表明冲击 H 参数曲线上的混合相区可能与罗息盐结构二氧化硅的逐渐形成有关。
