Unifying natural and laboratory chemical weathering with interfacial dissolution–reprecipitation: A study based on the nanometer-scale chemistry of fluid–silicate interfaces

Abstract

in particular the leached layer theory. Most importantly, our data provide critical evidence for 51 a single mechanism based on interfacial dissolution-reprecipitation. This concept not only 52 unifies weathering processes for the first time, but we also suggest that nanoscale-surface 53 processes can have a potentially negative impact on CO 2 uptake associated with chemical 54 weathering. The results in this study, when combined with recently published research on 55 fluid-assisted mineral replacement reactions, supports the idea that dissolution-reprecipitation 56 is a universal mechanism controlling fluid-mineral interactions . 57Based on this we propose the existence of a chemical weathering continuum based solely on 58 the interfacial dissolution-reprecipitation mechanism. 59 3

Pressure solution in rocks: focused ion beam/transmission electron microscopy study on orthogneiss from South Armorican Shear Zone, France

“…We suggest that the nano-scale observations of the quartz -white mica phase boundaries show direct evidence for operation of island-and-channel model as described in Wassmann and Stöckhert (2013), while K-feldspar -quartz phase boundaries represents amorphous layers formed via interface-coupled dissolution-reprecipitation as described by Hellmann et al (2012). …”

“…Although there is number of papers focusing on pressure solution and dissolution-precipitation, we will mainly discuss the models of Wassmann and Stöckhert (2013) and Hellmann et al (2012) for which we found direct evidence in our natural samples.…”

“…The development of different features along the phase boundaries is mainly controlled by the crystallography of the phases sharing a common interface, together with the presence of fluids that either leaches or directly dissolve the mineral phases. In addition, the local dislocation density in quartz may play an important role during pressure solution.We suggest that the nano-scale observations of the quartz -white mica phase boundaries show direct evidence for operation of island-and-channel model as described in Wassmann and Stöckhert (2013), while K-feldspar -quartz phase boundaries represents amorphous layers formed via interface-coupled dissolution-reprecipitation as described by Hellmann et al (2012). …”

“…This includes studies on chemical and biochemical weathering (e.g. Hellmann et al 2012;Daval et al 2013;Bray 2014), archaeological findings damage (e.g. Rodriguez-Navarro and Benning 2013) or during mineral replacement (e.g.…”

Foreword to the Research Front on ‘Mineral–Organic Interactions in Aqueous Systems’

“…[3] The environmental implications of mineral surface chemistry are manifold and diverse. They include atmospheric CO 2 drawdown associated with silicate mineral dissolution, [4,5] removal from solution of adsorptive metal and oxyanion contaminants, [6] nutrient retention for plant growth [7] and organic matter stabilisation against microbial biodegradation. [8] Through a combination of macroscopic experiments, molecular spectroscopy studies, and molecular modelling, environmental chemists are developing an improved understanding of the molecular-scale controls over the rates and extents of mineral surface reactions.…”