Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 5. Results of K-feldspar hydrolysis experiments  

作　　者：Peng Lu Hiromi Konishi Eric Oelkers Chen Zhu 

机构地区：[1]Department of Geological Sciences, Indiana University [2]EXPEC Advance Research Center, Saudi Aramco Oil Company [3]Department of Geology, Faculty of Science, Niigata University [4]Laboratoire de Geochimie, CNRS, 38 Rue Des Trente-Six Ponts,31400 Toulouse, France [5]Earth Sciences, University College London [6]Department of Earth Sciences, Zhejiang University

出　　处：《Chinese Journal Of Geochemistry》2015年第1期1-12,共12页中国地球化学学报

基　　金：grant from the State Key Laboratory of Ore Deposits at the Institute of Geochemistry, Chinese Academy of Sciences

摘　　要：This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fifth paper in our series of ‘‘Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems.'' In the previous four papers we presented batch experiments of alkali-feldspar hydrolysis and explored the coupling of dissolution and precipitation reactions(Fu et al. in Chem Geol91:955–964, 2009; Zhu and Lu in Geochim Cosmochim Acta 73:3171–3200, 2009; Zhu et al.in Geochim Cosmochim Acta 74:3963–3983, 2010; Lu et al. in Appl Geochem30:75–90, 2013). Here, we present the results of additionalK-rich feldspar hydrolysis experiments at 150 °C. Our solution chemistry measurements have constrained feldspar dissolution rates, and our high resolution transmission electron microscopy work has identified boehmite precipitation. Reaction path modeling of K-feldspar dissolution and boehmite precipitation simulated the coupled reactions, but only with forced changes of boehmite rate law in the middle of experimental duration. The results which are reported in this article lend further support to our hypothesis that slow secondary mineral precipitation explains part of the wellknown apparent discrepancy between lab measured and field estimated feldspar dissolution rates(Zhu et al. in Water–rock interaction, 2004).This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fifth paper in our series of ＂Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems.＂ In the previous four papers we presented batch experiments of alkali-feldspar hydrolysis and explored the coupling of dissolution and precipitation reactions （Fu et al. in Chem Geol 91：955-964, 2009; Zhu and Lu in Geochim Cosmochim Acta 73：3171-3200, 2009; Zhu et al.in Geochim Cosmochim Acta 74：3963-3983, 2010; Lu et al. in Appl Geochem 30：75-90, 2013）. Here, we present the results of additional K-rich feldspar hydrolysis experiments at 150℃. Our solution chemistry measurements have constrained feldspar dissolution rates, and our high resolution transmission electron microscopy work has identified boehmite precipitation. Reaction path modeling of K-feldspar dissolution and boehmite precipitation simulated the coupled reactions, but only with forced changes of boehmite rate law in the middle of experimental duration. The results which are reported in this article lend further support to our hypothesis that slow secondary mineral precipitation explains part of the well- known apparent discrepancy between lab measured and field estimated feldspar dissolution rates （Zhu et al. in Waterrock interaction, 2004）.

关 键 词：沉淀反应 水解实验 长石溶解 批处理系统 次生矿物 碱性长石 钾长石 高分辨透射电子显微镜 

分 类 号：P578.968[天文地球—矿物学]