The organic matter occluded in the silica of fossil diatom frustules is thought to be protected from diagenesis and used for paleoceanographic reconstructions. However, the location of the organic matter within the frustule has hitherto not been identified. Here, we combined high spatial resolution imaging by nanoSIMS and Raman micro-spectroscopy to identify where the organic material is retained in cleaned fossil diatom frustules. NanoSIMS imaging revealed that organic signals were present throughout the frustule but in higher concentrations at the pore walls. Raman measurements confirmed the heterogenous presence of organics but could not, because of lower spatial resolution, resolve the spatial patterns observed by nanoSIMS.

化石硅藻壳中的二氧化硅中所含的有机物被认为可以防止成岩作用，并用于古海洋重建。然而，迄今为止，还没有发现有机物质在壳中的位置。在这里，我们结合了nanoSIMS和拉曼显微光谱技术的高空间分辨率成像，以识别有机材料在清洁化石硅藻壳中的保留位置。NanoSIMS成像显示有机信号遍布整个壳状体，但在孔壁处浓度较高。拉曼测量证实了有机物的异质存在，但由于较低的空间分辨率而无法解析nanoSIMS观察到的空间模式。