Stability and Thermochemistry of some Chlorine-bearing Calcium Amphiboles

一些含氯钙角闪石的稳定性和热化学

• 批准号: 1725053
• 负责人: David Jenkins
• 金额: $ 28.91万
• 依托单位: SUNY at Binghamton
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1725053&HistoricalAwards=false
• 关键词: Stability; Thermochemistry; some; Chlorine; bearing

Chlorine-rich fluids are important agents in basic geological processes such as (i) transporting metal ions in aqueous brines, (ii) controlling the temperatures and depths in the Earth where hydrated crustal rocks react to denser anhydrous rocks (e.g., granulites and eclogites), and (iii) controlling the nature of the aqueous phase coexisting with silicate melts. These geological processes control, respectively, the formation of economic mineral deposits, the dynamics of mountain building and plate tectonics, and the style of volcanic eruptions. The details of how chlorine-rich fluids interact with crustal rocks are poorly understood, ranging from the near-surface incorporation of chlorine at the seawater-to-rock interface in oceanic crust to the migration of brines in mid- to lower-crustal levels. One of the most common rock-forming minerals into which chlorine is known to substitute at weight-percent levels is calcium-rich amphibole. The amount of chlorine that substitutes into amphiboles depends on the concentration of chlorine in the ambient brine or melt as well as the chemical composition of the host amphibole. A starting point for examining this complex interplay is to determine what compositional variables in the host amphibole exert the greatest control on its chlorine content. The first goal in this proposal is to examine the role that potassium plays, which, based on prior results obtained in this lab, now appears to be extremely important in controlling the chlorine content of amphiboles. Second, the effect of chlorine on the upper-thermal stability of this normally hydrous mineral will be investigated. Third, basic thermochemical data for one or more chlorine-rich amphiboles will be determined. Any rigorous analysis of the substitution of chlorine into an amphibole ultimately requires the fundamental thermochemical data for a given chlorine end-member amphibole. Obtaining these data, which simply do not exist at this time, would be a major contribution to the sciences. This proposal provides educational opportunities for undergraduate and graduate students, and welcomes the participation of under-represented minorities. Opportunities will also be made available for the training of pre-service Earth Science, Chemistry, Physics, and elementary teachers.Research in this proposal will focus on the following three main goals. First, the effect of several key compositional variables (ferrous iron content, potassium content) on the incorporation of chlorine into several calcium amphiboles will be examined. This will build on research already done at Binghamton University on potassium-free calcium amphiboles which were generally found to have very limited chlorine contents. Second, the upper-thermal stability of chlorine-rich amphiboles will be determined by phase-equilibrium methods and compared to the stabilities of their hydroxyl-rich equivalents. At present there are no experimental data demonstrating the effect of chlorine on the thermal stability of an amphibole, so that this information will be of considerable importance. Third, thermochemical data (volume, heat capacity, enthalpy of formation, and third-law entropy) will be obtained by a combination of direct measurements and derivation from the phase-equilibria data. Volume and heat capacity measurements can be made at Binghamton University, while the enthalpy of formation will entail measurements at the University of California at Davis. The third-law entropy will be derived from the thermal stability boundary. Thermochemical data on chlorine-rich amphiboles are absent in the scientific literature, yet such information is fundamental to any rigorous treatment of the partitioning of chlorine between amphibole-bearing rocks and the brine with which it equilibrates. Results from this study should be of interest to those working in a wide range of geological settings, including ocean-rock interactions, mantle chloride metasomatism, deep crustal and upper-mantle metamorphism, and ore-forming bodies and skarns.

富氯流体是基本地质过程中的重要因素，例如：(i)在含水盐水中运输金属离子，（ii）控制含水地壳岩石与密度较大的无水岩石（例如麻粒岩和榴辉岩）发生反应的地球温度和深度，以及（iii）控制与硅酸盐熔体共存的水相的性质。这些地质过程分别控制着经济矿床的形成、造山运动和板块构造运动的动力以及火山喷发的方式。富氯流体如何与地壳岩石相互作用的细节，从海洋地壳海水-岩石界面的近表面氯的结合到地壳中下部的盐水迁移，人们知之甚少。一种最常见的形成岩石的矿物是富含钙的角闪洞，氯气以其重量百分比代替了这种矿物。取代角闪洞的氯的数量取决于周围卤水或熔体中氯的浓度以及宿主角闪洞的化学成分。研究这种复杂的相互作用的一个出发点是确定宿主角闪孔中哪些成分变量对其氯含量施加最大的控制。本提案的第一个目标是检查钾所起的作用，根据本实验室先前获得的结果，钾在控制角闪石中的氯含量方面似乎非常重要。其次，氯对这种通常含水矿物的上热稳定性的影响将被研究。第三，将确定一个或多个富氯角闪石的基本热化学数据。任何对氯取代角闪孔的严格分析最终都需要给定氯端元角闪孔的基本热化学数据。获得这些当时根本不存在的数据，将是对科学的重大贡献。该提案为本科生和研究生提供了受教育的机会，并欢迎代表性不足的少数民族的参与。还将提供培训职前地球科学、化学、物理和小学教师的机会。本提案的研究将集中在以下三个主要目标上。首先，几个关键的组成变量（亚铁铁含量，钾含量）对氯进入几个钙角闪石的影响将被检查。这将建立在宾厄姆顿大学对无钾钙角闪石的研究基础上，这种角闪石通常被发现含有非常有限的氯。其次，富氯角闪石的上热稳定性将通过相平衡方法确定，并与它们的富羟基等效物的稳定性进行比较。目前还没有实验数据证明氯对角闪孔热稳定性的影响，因此这一信息将是相当重要的。第三，热化学数据（体积、热容、生成焓和第三定律熵）将通过相平衡数据的直接测量和推导相结合来获得。体积和热容的测量可以在宾厄姆顿大学进行，而生成焓的测量则需要在加州大学戴维斯分校进行。第三定律熵将由热稳定性边界导出。关于富氯角闪石的热化学数据在科学文献中是缺失的，然而这些信息对于任何严格处理含氯角闪石岩石和与之平衡的卤水之间氯的分配都是至关重要的。这项研究的结果应该对那些在广泛的地质环境中工作的人感兴趣，包括海洋-岩石相互作用，地幔氯化物交代，深部地壳和上地幔变质作用，以及成矿体和矽卡岩。

项目成果

CHLORINE-POTASSIUM RELATIONS IN HASTINGSITIC AMPHIBOLES

黑碱角闪石中的氯-钾关系

• DOI: 10.1130/abs/2020am-358490
• 发表时间: 2020
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Matteucci, Jared;Jenkins, David M.
• 通讯作者: Jenkins, David M.

Experimental study of metamorphic reactions and dehydration processes at the blueschist–eclogite transition during warm subduction

• DOI: 10.1111/jmg.12560
• 发表时间: 2020-08
• 期刊: Journal of Metamorphic Geology
• 影响因子: 3.4
• 作者: Nanfei Cheng;D. Jenkins

THERMOCHEMICAL VALUES OF CHLORO-HASTINGSITE AND QUANTIFYING CHLORINE CONCENTRATIONS OF HYDROTHERMAL SYSTEMS

氯黑位点的热化学值和热液系统氯浓度的定量

• DOI: 10.1130/abs/2019am-338555
• 发表时间: 2019
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Jenkins, David M.

The incorporation of chlorine into calcium amphibole

将氯掺入角闪石钙中

• DOI: 10.2138/am-2019-6768
• 发表时间: 2019
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Jenkins, David M.

STABILITY OF SODALITE RELATIVE TO NEPHELINE IN NACL-H2O BRINES AT 0.6 GPA AND 750 °C

0.6 GPA 和 750 °C 的 NACL-H2O 盐水中方钠石相对于霞石的稳定性

• DOI: 10.1130/abs/2018ne-311132
• 发表时间: 2018
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Schneider, Jonathan;Jenkins, David M.
• 通讯作者: Jenkins, David M.