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

高镁熔岩(科马提岩和苦苦岩)是中白垩世加勒比高原大火成岩省(LIP)中罕见但重要的组成部分。这些熔岩类型对于了解导致它们产生的地幔温度和动力学至关重要，但在其他大洋边缘省份是无法获得的。该项目是对哥斯达黎加最近发现的托图盖尔超镁铁质/镁铁质熔岩进行的综合野外、岩石学和地球化学研究。利用常量元素、微量元素、铂族元素和锶-钕-铅-Os同位素分析，结合40Ar-39Ar测年，对扭动熔岩进行定年，以进一步研究该区与唇部形成有关的岩石成因的时空变异性。托图盖尔套在时间上与东南1000公里处的戈尔戈纳岛科马提岩、苦苦岩和玄武岩有关，但初步数据显示两个地区在地幔来源和热体制方面存在显著差异。了解高镁熔岩的空间变异性将有助于区分加勒比高原形成的快速减压熔融或羽流头部模型。

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.