Collaborative Research: Using Melt Inclusions to Unravel Lithospheric Mantle and Crustal Contributions to Gondwana Flood Basalts and to Determine Pre-Eruptive Volatile Contents

该项目将使用熔融包裹体作为窗口，以了解冈瓦纳大陆主要溢流玄武岩省（巴拉那、埃滕德卡、卡鲁、费拉尔）下岩浆管道系统中熔融聚集和地壳同化过程的早期阶段。将通过电子探针（主要元素;挥发物- Cl、F、S）、激光烧蚀ICP-MS和MC-ICP-MS（微量元素; Pb同位素）和离子探针（H2O、CO2）分析均质化熔体包裹体。主要目标有两个方面：（1）利用来自地壳污染程度最低的样品的熔体包裹体中记录的成分多样性，看看它们是否保留了早期、污染程度较低的岩浆的证据，这些岩浆可能更好地限制源成分，以及这些源是否在岩石圈或亚岩石圈地幔中。(2)获得关于喷发前溢流玄武岩熔体的挥发性含量的数据，作为源特性的指标，挥发性饱和压力也将提供一种独特的手段，以确定熔体被污染和聚集的压力，从而为溢流玄武岩岩浆管道系统的结构提供新的见解。熔体包裹体数据将提供一种手段，通过它来估计挥发性的排放在熔岩喷发，并应有助于了解的过程负责的地方和全球的环境后果，在相对较短的时间间隔内如此巨大的岩浆喷发。这些结果将引起广大科学家的兴趣，包括那些参与古气候研究和全球气候变化可能原因建模的科学家。该项目将支持和加强俄勒冈州州立大学的地球化学实验室。

This project will use melt inclusions as a window into the earlier stages of the melt aggregation and crustal assimilation processes in magmatic plumbing systems beneath the main Gondwana flood basalt provinces (Parana, Etendeka, Karoo, Ferrar). Homogenized melt inclusions will be analysed by electron-microprobe (major elements; volatiles - Cl, F, S), laser ablation ICP-MS and MC-ICP-MS (trace elements; Pb isotopes), and ion-probe (H2O, CO2). The principal objectives are two-fold: (1) to use the diversity of compositions recorded in melt inclusions from the least crustally-contaminated samples to see whether they preserve evidence of earlier, less-contaminated magmas that might better constrain source compositions and whether these sources are in the lithospheric or sub-lithospheric mantle. (2) to obtain data on the pre-eruption volatile contents of flood basalt melts as an indicator of source characteristics, and volatile saturation pressures will also provide a unique means to determine the pressures at which melts are contaminated and aggregate and thus provide new insight into the architecture of flood basalt magma plumbing systems. The melt inclusion data will provide a means by which to estimate volatile emissions during lava eruptions and should aid the understanding of the processes responsible for the local and global environmental consequences of the eruption of such huge quantities of magma in a relatively short time interval. These results will be of interest to a broad range of scientists, including those involved in palaeoclimate studies and the modelling of the possible causes of global climate change. The project will support and enhance the geochemical laboratories at Oregon State University.