Geology, petrology and age determination of Archaean-Proterozoic basement rocks of western Uganda

该项目旨在通过提高我们对火山及其内部超基性结核的产生的理解，评估鲁文佐里山脉的隆起与托罗安科莱火山场火山作用的产生之间的关系。火山由一种不寻常的钾碱性火成岩组成，被称为kamafuite，这可以通过云母和富含斜辉石的地幔组合的部分熔融来解释，这些地幔组合与火山中的包体相似。Sr、Nd和Os的同位素将用于评估地壳和岩石圈地幔的吸收，从而评估地壳或地幔岩浆室中可能存在的物质。Re-Os将进一步揭示熔融地幔的性质，即软流圈或旧岩石圈及其富集程度。含云母和斜辉石捕虏体的岩石学和矿物化学特征将确定这些岩石是来自地幔的捕虏体还是来自kamafuites的地壳堆积。如果是地幔捕虏体，包括微量元素在内的矿物化学将被用来研究它们是橄榄岩普遍交代的结果还是仅限于矿脉。该地区普遍存在的地幔交代作用导致岩石圈体积的大量增加，这可能是鲁文佐里隆起的一个原因。

This project aims to assess the relationship of the uplift of the Rwenzori mountains to the generation of volcanism in the Toro Ankole volcanic field by improving our understanding of the generation of the volcanics and of the ultramafic nodules within them. The volcanics comprise an unusual type of potassic alkaline igneous rock known as kamafugite that may be explained by partial melting of mica and clinopyroxene-rich mantle assemblages similar to those found as xenoliths within the volcanics. Isotopes of Sr, Nd and Os will be used to assess the uptake of crust and lithospheric mantle and therefore the possible residence in crustal or mantle magma chambers. Re-Os will shed further light on the nature of the mantle that melted, namely asthenosphere or old lithosphere and the extent of its enrichment. Petrological and mineral chemical characterization of the mica- and clinopyroxenebearing xenoliths will ascertain whether these rocks are xenoliths from the mantle or crustal cumulates from the kamafugites. If mantle xenoliths, the mineral chemistry, including trace elements, will be used to investigate whether they are the result of pervasive metasomatism of peridotite or are restricted to veins. Pervasive metasomatism of the mantle has been proposed in this area to result in a large volume increase in the lithosphere - a possible reason for the uplift of the Rwenzoris.