Seeking Evidence for Reactive Assimilation in a Hybrid Pluton

PI寻求资金，以确定混合混合深成岩的源成分，并了解它们被纳入的机制。他提出，基本的过程包括分解和结晶物质与硅酸盐熔体反应的同化作用。特别地，可能不需要同化物的大规模熔化。相反，在同化物的部分熔融（例如脱水熔融）过程中形成的固体随着捕虏体的解体而被并入岩浆中。同化和结晶过程中的反应促进了捕虏体的化学混合和物理解体，并在很大程度上负责大量同化的隐蔽性。该项目的目标是确定火成岩内反映不同程度的地壳与地幔输入的中尺度和微尺度区域。这项工作将集中在岩相和矿物学的不均匀性，可能会保留证据的精细规模，神秘的混合，即使原始的纹理和矿物学已被修改的反应过程中同化和结晶。这项工作是专门针对矿物的识别和表征-无论是斑晶或捕虏晶-早于杂交事件以及反应物矿物进行混合签名。PI建议在弗吉尼亚州南部的马廷斯维尔火成岩杂岩（MIC）中研究这些过程，这是一种具有混合同位素特征的辉长岩-辉长岩杂岩。MIC非常适合这项研究，因为：1）同位素化学与MIC内的主要和微量元素化学密切相关; 2）该系统（玄武岩侵入泥质岩）地质特征良好，对比强烈，简单; 3）已在岩体中鉴定出矿物和矿物凝块，并初步解释为来自围岩。此外，岩石学上独特的阶段，包括分区，尘埃斜长石的岩体和蓝石英的围岩提供了明显的分析目标。要获得的数据包括一套完整的岩石分析，矿物化学和分区数据，包括主要和微量元素和氧同位素。更广泛的影响：PI将把这项研究的信息纳入他正在进行的K-12教师培训计划，其中已经包括了花岗岩岩浆的起源和成分的大部分。如果这一建议得到支持，将寻求更多的支持，以创建一个基于调查的火成岩展览，强调拟议的研究结果。该博物馆是经济萧条地区（企业区）学校参观和替代学习的焦点，该地区约50%的学龄人口是非洲裔美国人和西班牙裔。

The PI seeks funding to identify source components in hybrid mixed plutonic rocks and to understand the mechanisms by which they are incorporated. He proposes that the fundamental process involves assimilation by disaggregation and reaction of crystalline materials with silicate melts. In particular, wholesale melting of assimilant may not be required. Instead, solids formed during partial melting (e.g. dehydration melting) of the assimilant are incorporated into the magma as the xenolith disaggregates. Reactions during assimilation and crystallization promote both chemical mixing and physical disintegration of xenoliths and are largely responsible for the cryptic character of bulk assimilation. The goal of this project is to identify mesoscale and microscale regions within igneous rocks that reflect varying degrees of crust vs. mantle input. The work will focus on petrographic and mineralogical heterogeneities that may preserve evidence of fine-scale, cryptic mixing even if original textures and mineralogy have been modified by reactive processes during assimilation and crystallization. The work is specifically aimed at the identification and characterization of minerals - either phenocrysts or xenocrysts - that predate the hybridization event as well as reactant minerals that carry a hybrid signature. The PI proposes to investigate these processes in the Martinsville Igneous Complex (MIC) in southern Virginia, a gabbro-diorite complex with a hybrid isotopic signature. The MIC is well-suited for this study because; 1) isotope chemistry is strongly correlated with major and trace element chemistry within the MIC; 2) the system (a basaltic intrusion into pelitic rocks) is geologically well-characterized, highly contrasting, and simple and; 3) minerals and mineral clots have been identified in the pluton that are tentatively interpreted as being derived from the country rocks. Additionally, petrographically distinctive phases, including zoned, dusty plagioclase in the pluton and blue quartz in the country rocks provide obvious analytical targets. Data to be acquired unclude a suite of whole rock analyses, and mineral chemical and zoning data including major and trace elements and oxygen isotopes.Broader impacts: The PI will incorporate information from this study into his ongoing program of K-12 teacher training, which already includes a large component on the origin and composition of granitic magmas. If this proposal is supported, additional support will be sought to create an inquiry-based exhibit on igneous rocks that emphasizes the results of the proposed research. This museum is a focal point for school visitation and alternative learning in an economically depressed region (Enterprise Zone) where approximately 50% of the school-age population is African-American and Hispanic.