Mechanisms of alteration of basaltic and rhyolitic glasses considering solution chemistry and passivating properties of palagonite - a case study on ICDP drilling sites Hawaii and Snake River Plain

考虑溶液化学和八角长石钝化特性的玄武岩和流纹岩玻璃的蚀变机制 - 以夏威夷和斯内克河平原 ICDP 钻探地点为例

基本信息

批准号：
215411906
负责人：
Professor Dr. Harald Behrens
金额：
--
依托单位：
Institut für Mineralogie
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/215411906?language=en
关键词：
Mechanisms alteration basaltic rhyolitic glasses

项目摘要

Alteration layers on basaltic and rhyolitic glasses are common in volcanic rocks. Such layers denoted as palagonite have strong influence on transformation of glasses to crystalline phases and reactions of glasses with other rock components or fluids, the latter being of great importance for element release. In particular palagonite may act as diffusion barrier that slows down or even inhibit glass alteration. The effect of such a barrier may change over time due to polymerization and precipitation reactions which affect porosity and permeability. Microorganisms forming pits and tubes in basaltic glass surfaces may provide routes in palagonite which enhance abiotic glass alteration too. Findings on porosity and nonequilibrium textures in alteration layers, and a new model on an interface-coupled dissolution reprecipitation mechanism encouraged us to use altered glass samples in combination with experimental work to determine the relationship between glass alteration and palagonite properties, in particular effects of porosity of layers and solution chemistry on glass weathering rate. Chemically different basaltic and rhyolitic glasses available from ICDP drilling cores Hawaii and Snake River Plain exposed to saline and different fresh waters at temperatures allowing microbial colonization will be included. Our planned research involves (i) a petrographical investigation of glass alteration with focus on texture, (ii) the characterization of pore systems using N2-adsorption, Hg-porosimetry, impregnation with a molten alloy and various microscopic techniques, (iii) an experimental study of transport in pore spaces, (iv) determination of ionic effects on glass dissolution traced by zeta-potential and element release rates considering biochemical factors, and (v) fluid-glass experiments at conditions relevant to the drilling sites. Knowledge of these interactions is needed to understand and predict interdependencies of palagonite formation, glass alteration rates, solution composition and biochemical factors.

玄武岩和流纹镜玻璃上的改变层在火山岩中很常见。这种表示为palo岩的层对玻璃的转化对结晶相和玻璃与其他岩石组件或流体的反应有很大影响，后者对于元素释放非常重要。尤其是紫杉铁矿可能充当扩散屏障，减慢甚至抑制玻璃改变。由于聚合和影响孔隙度和渗透性的降水反应，这种屏障的影响可能会随着时间而变化。在玄武岩玻璃表面形成凹坑和管子的微生物可能会提供紫杉铁的路线，从而增强了非生物玻璃的改变。关于变化层中孔隙率和非平衡纹理的发现，以及界面耦合的溶解重新沉淀机制的新模型鼓励我们将改动的玻璃样品与实验工作结合使用，以确定玻璃改变与帕尔医学性质之间的关系，特别是在层的孔隙率和解决方案化学对玻璃风雨速度的效果上。 ICDP钻井核心可提供的化学上不同的玄武岩和流纹状玻璃包括在允许微生物定植的温度下暴露于盐水和不同新鲜水域的蛇河平原。 Our planned research involves (i) a petrographical investigation of glass alteration with focus on texture, (ii) the characterization of pore systems using N2-adsorption, Hg-porosimetry, impregnation with a molten alloy and various microscopic techniques, (iii) an experimental study of transport in pore spaces, (iv) determination of ionic effects on glass dissolution traced by zeta-potential and element release rates考虑生化因子和（v）与钻井部位相关的条件下的流体玻璃实验。需要了解这些相互作用，以理解和预测葡萄球形成，玻璃改变速率，溶液组成和生化因素的相互依赖性。