High-Pressure Study of Some Large Ions in Mantle Minerals

9903203Harlow 拟议的研究是在高压和高温下对富含钾和氟的矿物/相进行实验研究，这些矿物/相可能在地球上地幔的各种含水环境中保持稳定。 这项研究将从两种化合物开始，这两种化合物已被证明在这种地球条件下是稳定的，但在其他方面还没有得到充分的了解；这些相包括钾长石的含水类似物 K-cymrite (KAlSi3O8onH2O) 和 KMgF3，一种用作硅酸盐钙钛矿类似物的钙钛矿结构相。 该研究将 1) 确定矿物中这些相的压力和温度稳定性上限（适合已知地幔岩石和俯冲到地幔的候选地壳岩石的流体组合），2) 表征相的成分、OH 含量和结构状态，以及 3) 确定组成元素的相间分配。 实验中包括的其他物相包括氟金云母、多晶云母、氟钾丽霞石和钾长石，本研究知识的结果也将提高对其稳定性条件的了解。 实验将在 Walker 型多砧装置中进行，产品将通过电子显微探针、扫描电子显微镜和阴极发光成像、X 射线衍射和 FT-IR 光谱的组合进行分析。 与元素分配到流体和熔体相比，该研究的结果将用于改进对地幔储层中钾和氟储存的预测。

9903203Harlow The proposed research is an experimental investigation at high pressure and temperature of potassium- andfluorine-rich minerals/phases that may be stable in variably hydrous environments of Earth's upper mantle. The study will start with a pair of compounds that have been demonstrated to be stable at such Earth conditions but are otherwise inadequately understood; these phases include K-cymrite (KAlSi3O8onH2O), the hydrous analog of K-feldspar, and KMgF3, a perovskite-structure phase used as an analog for silicate perovskites. The research will 1) determine the upper range of pressure and temperature stability of these phases in mineral(fluid assemblages appropriate to known mantle rocks and to crustal rocks that are candidates for subduction into the mantle, 2) characterize the phases with respect to composition, OH content, and structural state, and 3) determine the inter-phase partitioning of constituent elements. Other phases to be included in experiments will be fluorphlogopite, phengitic mica, fluor-K-richterite, and K-feldspar, and results from this study knowledge will improve the knowledge of their stability conditions as well. Experiments will be carried out in Walker-type multianvil apparati, and products will be analyzed by a combination of electron microprobe, scanning-electron microscopic and cathodoluminescence imaging, x-ray diffraction, and FT-IR spectroscopy. Results from the research will be used to improve predictions of the storage of potassium and fluorine in reservoirs in the mantle as compared to the elements' partitioning into fluids and melts.