Fossils, including those that occasionally preserve decay-prone soft tissues, are mostly made of minerals. Accessing their chemical composition provides unique insight into their past biology and/or the mechanisms by which they preserve, leading to a series of developments in chemical and elemental imaging. However, the mineral composition of fossils, particularly where soft tissues are preserved, is often only inferred indirectly from elemental data, while X-ray diffraction that specifically provides phase identification received little attention. Here, we show the use of synchrotron radiation to generate not only X-ray fluorescence elemental maps of a fossil, but also mineralogical maps in transmission geometry using a two-dimensional area detector placed behind the fossil. This innovative approach was applied to millimetre-thick cross-sections prepared through three-dimensionally preserved fossils, as well as to compressed fossils. It identifies and maps mineral phases and their distribution at the microscale over centimetre-sized areas, benefitting from the elemental information collected synchronously, and further informs on texture (preferential orientation), crystallite size and local strain. Probing such crystallographic information is instrumental in defining mineralization sequences, reconstructing the fossilization environment and constraining preservation biases. Similarly, this approach could potentially provide new knowledge on other (bio)mineralization processes in environmental sciences. We also illustrate that mineralogical contrasts between fossil tissues and/or the encasing sedimentary matrix can be used to visualize hidden anatomies in fossils.

中文翻译：

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使用同步同步加速器 X 射线荧光和 X 射线衍射图可视化矿化过程和化石解剖结构

化石，包括那些偶尔保存易腐烂的软组织的化石，主要由矿物质组成。访问它们的化学成分可以提供对它们过去生物学和/或它们保存机制的独特见解，从而导致化学和元素成像的一系列发展。然而，化石的矿物成分，尤其是软组织被保存的地方，通常只能从元素数据中间接推断出来，而专门提供物相识别的 X 射线衍射很少受到关注。在这里，我们展示了使用同步加速器辐射不仅生成化石的 X 射线荧光元素图，而且使用放置在化石后面的二维区域探测器生成透射几何中的矿物学图。这种创新方法被应用于通过三维保存的化石制备的毫米厚的横截面，以及压缩的化石。它从同步收集的元素信息中识别并绘制矿物相及其在厘米大小区域的微观分布，并进一步了解纹理（优先取向）、微晶尺寸和局部应变。探索此类晶体学信息有助于确定矿化序列、重建化石环境和限制保存偏差。同样，这种方法可能会提供有关环境科学中其他（生物）矿化过程的新知识。