Influence of pH and temperature on the early stage of mica alteration

Abstract

a b s t r a c tMineral dissolution and precipitation reactions actively participate in controlling fluid chemistry during water-rock interaction. In this study, the changes in the biotite and muscovite basal surface nano-morphology were evaluated during interaction with fluids of different pH (pH = 1.1, 3.3 and 5.7) at different temperatures (T = 25°, 120°, and 200°C). Results show that at the nanometre scale resolution of the atomic force microscope (AFM), dissolution generates etch pits with a stair-shaped pattern over the (0 0 1) surface. The flux of dissolved elements decreases when pH increases. However, at pH 5.7, a change was found in the flux after 42 h of reaction when abundant gibbsite and kaolinite coat the dissolving mineral surface. This phenomenon was widely observed at edges of the etch pits by AFM. It was also found that an increase in temperature produces an enhancement in the elemental flux in both micas. Dissolution regime changes after less than one day of interaction at high temperature because of abundant coating formation over the etch pits and edges. The results demonstrate the key role of nanometre size neogenic phases in the control of elemental flux from mica surfaces to solution. The formation of nanometre size coatings, blocking the sites active for dissolution, appears to control the alteration of phyllosilicates even at the early stage of the interaction.

Effects of citrate on the dissolution and transformation of biotite, analyzed by chemical and atomic force microscopy

“…However, the release of Si and Al in the framework of biotite differed from that of K (Maslova et al, 2005;Pachana et al, 2012). Release rates of Si and Al with pH 4.0 citrate solution treatment were increased by 0.2 and 1.2 times, respectively, of the corresponding aqueous solution,.…”

“…In the presence of H + ions, aluminosilicate reacts according to the equation: Al 2 Si 2 O 5 (OH) 4 + 6H + = 2Al 3+ + 2H 4-SiO 4 + H 2 O (Kalinowski and Schweda, 1996); therefore, the coating was speculated to be an amorphous Si-bearing mineral (Shao et al, 2011;Teng et al, 2001;White and Brantley, 1995). Through the clues from boron (B) isotopes in biotite, researchers found that when pH > 4.0, the transformation rate of biotite was significantly greater than the dissolution rate of biotite (Voinot et al, 2013), namely, in a closed and steady environment, the growth of nucleation was relatively effortless on the solid-liquid interface (Pachana et al, 2012).…”

“…In situ AFM studies of biotite basal found that the biotite (0 0 1) surface became ''rougher'' with hydrochloric acid (pH = 1.26), while with oxalic acid (pH = 1.32) there were many etch pits formed and grown (Haward et al, 2011;McMaster et al, 2008). The dissolution process is not always continued during long-term reactions with hydrothermal solutions that have abundant gibbsite and kaolinite coating the dissolving mineral surface (Pachana et al, 2012). This phenomenon could also be seen in the dissolution of phlogopite and orthoclase (Shao et al, 2011;Teng et al, 2001).…”

Influences of pH and CO2 on the formation of Metasilicate mineral water in Changbai Mountain, Northeast China

“…Oelkers et al (2008) gave an overview on the steady-state muscovite dissolution rates at temperatures from 60 to 201°C and 1 B pH B 10.3 as a function of reactive solution K, Si, and Al concentration. The findings of Pachana et al (2012) in analyzing the dissolution generates etch in the surface of biotite and muscovite basal at different pH values (pH 1.1, 3.3, and 5.7) and different temperatures (T = 2.5, 120, and 200°C) were very important, as he concluded that dissolution regime changes with pH values and temperatures. Skopljak and Vlahović (2012) wrote about the genesis of mineral waters in Kiseljak surroundings, and pointed out that the water origin from atmospheric and water descends in the primary aquifer where it becomes enriched with CO 2 and minerals.…”

“…Key factors influencing water-rock interaction include temperature, pH, pressure, catalysis, and rock characteristics (Gérard et al 2002;Oelkers et al 2008;Gysi and Stefánsson 2011;Pachana et al 2012). Gérard et al (2002) investigated the relationships between Si concentration, soil temperature, and H ?…”