Crystallization conditions of carbonatites and associated alkaline silicate rocks

碳酸盐岩和伴生碱性硅酸盐岩石的结晶条件

• 批准号: 390235678
• 负责人: Privatdozent Dr. Michael Marks
• 金额: --
• 依托单位: Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik (BGI)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/390235678?language=en
• 关键词: Crystallization; conditions; carbonatites; associated; alkaline

Most of the known carbonatite occurrences are spatially and temporally associated with alkaline to peralkaline silicate rocks. The redox conditions during the crystallization of alkaline to peralkaline silicate rocks show considerable variation. The redox conditions estimated for carbonatites, however, seem to be relatively restricted, although their association with alkaline-peralkaline rocks silicate rocks is so typical. This project will investigate (1) the prevailing redox conditions during the crystallization of carbonatitic rocks in general by studying several suitable carbonatite occurrences world-wide and (2) the similarity or difference of redox conditions between carbonatites and spatially and temporally associated alkaline rocks focusing on two typical plutonic and subvolcanic carbonatite-alkaline rock associations (Kaiserstuhl and Kovdor). The silicate-oxide-sulfide assemblages in the samples to be investigated will be studied in detail by means of microscopy, EMPA, oxygen isotope and Mössbauer work to determine their crystallization conditions in terms of fO2, T, aSiO2, and fS2.The expected results will (1) constrain the prevailing redox conditions and possible variations during the crystallization of carbonatitic melts and (2) clarify whether carbonatites and associated alkaline rocks at a given locality crystallize under similar or different redox conditions. In a more general sense, the results of this project are expected to contribute to our knowledge on the variability of redox conditions in the lithospheric mantle (for which carbonatites and alkaline silicate rocks are suitable probes) and the physico-chemical processes involved during the evolution from carbonate-bearing mantle melts towards carbonatites and associated alkaline rocks.

大多数已知的碳酸盐岩发生在空间和暂时与葡萄糖与甲烷烃硅岩石相关。酒精碱到钙氨硅岩石结晶期间的氧化还原条件显示出很大的变化。然而，尽管碳酸盐岩与硅胶岩石岩石岩石的关联是如此典型，但估计碳酸盐估计的氧化还原条件似乎是相对限制的。该项目将通过研究全球范围内的几种合适的碳酸盐岩发生在碳岩岩石结晶过程中的流行氧化还原条件，以及（2）（2）碳酸盐岩与空间和临时酒精岩石之间的氧化还原条件的相似性或差异，专注于两个典型的plutionic和subvolcanitonic cobanatite coclanite-cocerline rockiations-kaiisiations and kaiisiations（KA）。将通过显微镜，EMPA，EMPA，氧同位素和Mössbauer工作详细研究要研究的样品中的硅酮 - 氧化物组合，以确定其结晶条件，以FO2，T，ASIO2和FS2来确定其结晶条件。澄清在给定位置的碳酸盐和相关的酒精岩石是否在相似或不同的氧化还原条件下结晶。从更一般的意义上讲，该项目的结果有望有助于我们对岩石圈地幔中氧化还原条件的可变性的了解（对于碳酸盐的地幔融化了碳酸盐岩的含碳酸盐地幔融化，向碳酸盐融化了碳酸盐和相关的酒精岩石。