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

该项目将利用熔体包裹体作为一个窗口，了解冈瓦那主要的洪水玄武岩省(巴拉那省、埃滕代卡省、卡鲁省、费拉省)下岩浆管道系统中熔体聚集和地壳同化过程的早期阶段。均一化的熔体包裹体将用电子探针(主要元素；挥发物-Cl、F、S)、激光烧蚀电感耦合等离子体质谱(ICPMS)和MC-ICPMS(痕量元素、铅同位素)和离子探针(H2O、CO2)进行分析。主要目标有两个：(1)利用地壳污染最少的样品在熔体包裹体中记录的成分的多样性，看看它们是否保存了可能更好地限制来源成分的较早、污染较少的岩浆的证据，以及这些来源是在岩石圈还是岩石圈下地幔中。(2)获取有关溢流玄武岩熔体喷发前挥发分含量的数据作为来源特征的指标，挥发饱和压力也将提供一种独特的手段来确定熔体被污染和聚集的压力，从而对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，用于估计熔岩喷发期间的挥发性排放，并应有助于理解在相对较短的时间间隔内大量岩浆喷发对当地和全球环境造成影响的过程。这些结果将引起广泛的科学家的兴趣，包括那些参与古气候研究和建立全球气候变化可能原因模型的科学家。该项目将支持和加强俄勒冈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.