Fluorine-, yttrium- and lanthanide-rich cerianite-(Ce) from carbonatitic rocks of the Kerimasi volcano and surrounding explosion craters, Gregory Rift, northern Tanzania
Fluorine-, yttrium- and lanthanide-rich cerianite-(Ce) from carbonatitic rocks of the Kerimasi volcano and surrounding explosion craters, Gregory Rift, northern Tanzania
复制标题
富含氟、钇和镧系元素的铍长石（Ce），来自坦桑尼亚北部格雷戈里裂谷的克里马西火山和周围爆炸坑的碳酸盐岩
DOI：
10.1180/minmag.2011.075.6.2813
复制
发表时间：
2011
影响因子：
2.7
通讯作者：
E. Polyakova
中科院分区：
文献类型：
--
作者：
A. Zaitsev;A. Chakhmouradian;O. Siidra;J. Spratt;C. Williams;C. Stanley;S. V. Petrov;S. Britvin;E. Polyakova
摘要铈矿-（Ce），理想的CeO 2，以直径达5 μm的圆形颗粒存在于Kerimasi火山高度蚀变的方解石碳酸岩熔岩中，并以直径达200 μm的自形晶体存在于坦桑尼亚北方格雷戈里裂谷的Kisete和Loluni火山口碳酸岩衍生的残积物中。X射线粉末衍射数据（α = 5.434（5）λ）和拉曼光谱（除了在449 cm-1处的强信号之外，在184和571 cm-1处的小振动模式）表明在Kisete材料中存在必需量的大阳离子和氧空位。微探针分析表明，该矿物含有轻、重三价稀土元素（7.9- 15.5wt%）LREE 2 O3和4.9-9.7重量% HREE 2 O3），并且其富含钇（7.1-14.5重量% Y2 O3）和氟（2.2-3.5重量%）。矿物的单晶结构精修证实了萤石型结构，阳离子-阴离子距离为2.3471（6）nm。铈矿-（Ce）被认为是碳酸岩中的晚期次生矿物。
Abstract Cerianite-(Ce), ideally CeO2, occurs as rounded grains up to 5 μm across in a block of highly altered calcite carbonatite lava from the Kerimasi volcano, and as euhedral crystals up to 200 μm across in carbonatite-derived eluvial deposits in the Kisete and Loluni explosion craters in the Gregory Rift, northern Tanzania. X-ray powder diffraction data (a = 5.434(5) Å ) and Raman spectroscopy (minor vibration modes at 184 and 571 cm-1 in addition to a strong signal at 449 cm-1) suggest the presence of essential amounts of large cations and oxygen vacancies in the Kisete material. Microprobe analyses reveal that the mineral contains both light and heavy trivalent rare earth elements (REE) (7.9-15.5 wt.% LREE2O3 and 4.9-9.7 wt.% HREE2O3), and that it is enriched in yttrium (7.1-14.5 wt.% Y2O3) and fluorine (2.2-3.5 wt.%). Single-crystal structure refinement of the mineral confirms a fluorite-type structure with a cation anion distance of 2.3471(6) Å. The cerianite-(Ce) is considered to be a late-stage secondary mineral in the carbonatitic rocks.