Impact of composition and local, bulk and surface structure of fibrous carbonates on their fabric and morphology

尽管含有放射状纤维状和/或束状光学方解石胶结物的碳酸盐被认为是古海洋地球化学的最佳替代物之一，但对其形成及其异常性质的结构起源知之甚少。因此，在本项目中，将研究纤维状放射状方解石的体积和表面结构和组成以及种子形成和生长条件。使用晶体学技术，如晶体结构的分析，全局和空间分辨，以及表面的组成和结构的分析，将获得结构，组成和形态的最完整的关系。天然和合成（实验）样品的比较应允许合理理解所涉及的过程。在晶体生长实验中，也将讨论有节奏生长的问题。特别是改变母液的组成对晶体的形态和组成的影响是有意义的。所有产品都将进行晶体学表征。此外，有机分子，如氨基酸，糖，木质素等的生长过程中的影响将研究考虑微晶形成条件。为了理解原子分辨率的过程，从与这些有机物相互作用的大型方解石晶体的模型系统，包括有机添加层的表面结构将使用掠入射X射线衍射（GIXRD）和原子力显微镜（AFM）实验进行分析。

Although carbonates containing radiaxial fibrous and/or fasicular optical calcite cements are considered to be one of the best proxies for the geochemistry of ancient oceans, their formation and the structural origin of their unusual properties are only poorly understood. Therefore, in this project bulk and surface structure and composition of fibrous radiaxial calcites will be studied together with seed formation and growth conditions. Using crystallographic techniques such as the analysis of the crystal structure, globally and space resolved, and the analysis of the composition and structure of surfaces, a most complete relation of structure, composition and morphology will be obtained. The comparison of natural and synthetic (experimental) samples should allow for a rational understanding of processes involved. In crystal growth experiments also the question of rhythmic growth will be addressed. In particular the influence of changing composition of mother liquor on the morphology and composition of the crystal is of interest. All products will undergo crystallographic characterization. In addition, the influence of organic molecules such as amino acids, sugars, lignin etc. on the growth process will be studied considering micrite formation conditions. For an understanding of processes in atomic resolution, from model systems of large calcite crystals interacting with these organics, the structure of the surface including the organic add-layer will be analyzed using grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) experiments.