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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.

玄武岩和流纹质玻璃上的蚀变层在火山岩中很常见。这些层被称为斜长岩，它们对玻璃向晶相的转化以及玻璃与其他岩石组分或流体的反应有很大影响，后者对元素释放非常重要。特别是斜长岩可以作为扩散屏障，减缓或甚至抑制玻璃蚀变。由于影响孔隙率和渗透性的聚合和沉淀反应，这种屏障的效果可能随时间而改变。微生物在玄武岩玻璃表面形成的坑和管可能提供途径的斜长岩，增强非生物玻璃蚀变。在蚀变层的孔隙度和非平衡纹理的调查结果，和一个新的模型界面耦合溶解再沉淀机制鼓励我们使用改变玻璃样品结合实验工作，以确定玻璃蚀变和斜长岩性质之间的关系，特别是层的孔隙度和溶液化学对玻璃风化速率的影响。将包括在允许微生物定植的温度下暴露于盐水和不同新鲜沃茨的ICDP钻井岩心夏威夷和蛇河平原中的化学性质不同的玄武岩和流纹岩玻璃。我们计划的研究包括（i）玻璃蚀变的岩相学研究，重点是纹理，（ii）使用N2吸附，Hg孔隙率测定，熔融合金浸渍和各种显微技术表征孔隙系统，（iii）孔隙空间中运输的实验研究，（iv）考虑到生物化学因素，通过zeta电位和元素释放速率来确定离子对玻璃溶解的影响，以及（v）在与钻探地点相关的条件下的流体玻璃实验。这些相互作用的知识是需要了解和预测的相互依赖性的斜长岩的形成，玻璃蚀变率，解决方案的组成和生物化学因素。