Collaborative Research: Geochemical Investigation of the Tortugal Komatiites of Costa Rica

pylehigh MgO熔岩（komatiites和苦荞岩）是中白垩世加勒比海高原大火成岩省（LIP）中罕见但重要的组成部分。这些熔岩类型对于了解导致其产生的地幔温度和动力学至关重要，但在其他海洋LIP省份却无法获得。该项目是对哥斯达黎加最近发现的Tortugal超基性/基性熔岩进行综合实地、岩石学和地球化学研究。利用主元素、微量元素、铂族元素和Sr-Nd-Pb-Os同位素分析，结合40Ar-39Ar测年，对该地区Tortugal熔岩进行特征分析，以进一步记录该地区与LIP形成相关的岩石成因时空变化。Tortugal套在时间上与东南方向1000 km处的goorgona岛的科马长岩、苦橄岩和玄武岩有关，但初步资料显示两个地区在地幔源和热状态上存在显著差异。了解高MgO熔岩的空间变动性将有助于区分加勒比高原形成的快速减压融化或羽头模式。

9902855PyleHigh MgO lavas (komatiites and picrites) are a rare but important component of the mid-Cretaceous Caribbean plateau large igneous province (LIP). These lava types are critical to understanding mantle temperature and dynamics that lead to their production but are inaccessible in other oceanic LIP provinces. This project is an integrated field, petrological and geochemical study of the recently discovered Tortugal ultramafic/mafic lavas of Costa Rica. Major element, trace element, platinum group element and Sr-Nd-Pb-Os isotope analyses, combined with 40Ar-39Ar dating, will be used to characterize the Tortugal lavas in order to further document the spatial and temporal variability in petrogenesis related to LIP formation in the region. The Tortugal suite is temporally related to the Gorgona Island komatiites, picrites and basalts 1000 km to the southeast, however preliminary data show significant differences in mantle source and thermal regime between the two areas. Understanding the spatial variability in high MgO lavas will help distinguish between rapid decompression melting or plume head models for the creation of the Caribbean plateau.