RUI: Thermal Consequences and Textural Signatures of Reinjection in Mafic Sills

RUI：镁铁质基岩回注的热后果和结构特征

• 批准号: 1551247
• 负责人: Michael Zieg
• 金额: $ 16.34万
• 依托单位: Slippery Rock University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2021-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1551247&HistoricalAwards=false
• 关键词: RUI; Thermal; Consequences; Textural; Signatures

Just as volcanoes have alternating periods of eruption and repose, igneous intrusions can also have alternating periods of injection and crystallization. This study will provide a better understanding of the emplacement process and its effects in intrusive systems, specifically in mafic sills. The study will identify the diagnostic physical and chemical signatures of magma reinjection into a partially crystalline system and the specific textural characteristics of a reinjection horizon that can be used to determine its timing and thermal conditions. Diagnostic criteria for recognizing reinjections in mafic systems will allow this process to be positively identified in other intrusions and will place important constraints on models for magma chamber formation and evolution. In addition, the data to be developed (texture, composition, and mineralogy profiles) will be widely distributed as a resource for developing and testing petrologic hypotheses, and for recognizing additional processes beyond those specifically addressed in this study.The primary goal of this study is to define the detailed signature of reinjection events using a continuous drill core profile through a diabase sill (the Black Sturgeon sill) from Nipigon, Ontario. Petrographic data will include modal mineralogy, textures (crystal size distributions), and fabric (alignment factor). Geochemical data will include bulk-rock major and trace-element chemistry and mineral compositions. Preliminary results have been used to tentatively identify the positions and effects of several reinjection events in the Black Sturgeon sill. This project will document the fine-scale variations around these sites and locate and characterize other potential reinjection zones. These textural and compositional variations will provide a set of discrete criteria that can be used to demonstrate and document the existence of reinjection horizons in magmatic systems. Numerical cooling models will then be integrated with textural observations and with MELTS modeling to provide quantitative constraints on the emplacement history of the Black Sturgeon sill, including the timing and spatial distribution of the individual replenishment events.

正如火山有交替的喷发期和休止期，火成岩侵入物也有交替的注入期和结晶期。这项研究将有助于更好地理解侵入过程及其对侵入系统的影响，特别是对岩石技能的影响。该研究将确定岩浆再注入部分结晶系统的诊断性物理和化学特征，以及可用于确定其时间和热条件的再注入层的特定结构特征。识别基性系统中再注入的诊断标准将使这一过程在其他侵入中得到积极识别，并将对岩浆房形成和演化模型施加重要约束。此外，待开发的数据（结构、成分和矿物学剖面）将广泛分布，作为开发和测试岩石学假设的资源，并用于识别本研究中专门讨论的其他过程。本研究的主要目标是通过安大略省Nipigon的辉绿岩储层（Black Sturgeon储层）的连续岩心剖面来定义回注事件的详细特征。岩石学数据将包括模态矿物学、结构（晶体尺寸分布）和结构（排列因子）。地球化学数据将包括大块岩石主要元素和微量元素化学和矿物组成。初步结果已用于初步确定几次回注事件在黑鲟池中的位置和影响。该项目将记录这些地点周围的细微变化，并定位和描述其他潜在的回注区。这些结构和成分的变化将提供一套离散的标准，可用于证明和记录岩浆系统中回注层的存在。然后，数值冷却模型将与纹理观测和熔融体建模相结合，以提供黑鲟鱼储层就位历史的定量约束，包括单个补给事件的时间和空间分布。