Pedogenic weathering of tonalite in southern California

Identifying a reference frame for calculating mass change during weathering: A review and case study utilizing the C# program assessing element immobility and critical ratio methodology

“…However, as shown below the resulting estimates of elemental and bulk mass change produce a coherent picture of regolith development that is consistent with existing petrologic and clay mineralogic data and our knowledge of common fluid-rock interactions (e.g., Nettleton et al, 1970;Nesbitt, 1979;Nesbitt andYoung, 1984, 1989;Nesbitt and Markovics, 1997;White et al, 2001;Graham et al, 2010;Girty et al, 2014;Parizek and Girty, 2014). For instance, the transformation of biotite to vermiculite is widely recognized as a common alteration process occurring within the regolith, as is the translocation of clay particles (April et al, 1986;April et al, 2004;Aspandiar and Eggleton, 2006;Bisdom et al, 1982;Harraz and Hamdy, 2010;Jolicoeur et al, 2000;Nettleton et al, 1970;Wilson, 2004). Hence, our expectation is that mass balance calculations utilizing the selected framework elements will indicate that K mass has been lost from ZR I and ZR II, while the translocation of kaolinite (Al 2 Si 2 O 5 (OH) 4 ) into the saprock system at ZR III should have introduced an increase in Si and Al mass.…”

“…It is therefore not surprising that as fluids continued to access the biotite structure, loss of K mass persisted, and ultimately resulted in small amounts of kaolinite forming at this site. Such reactions between downward migrating solutions and biotite are well documented in the literature (April et al, 1986;April et al, 2004;Aspandiar and Eggleton, 2006;Bisdom et al, 1982;Harraz and Hamdy, 2010;Jolicoeur et al, 2000;Nettleton et al, 1970;Wilson, 2004). However, the interplay between fluids and the base silicate framework did not produce a statistically significant change in bulk mass (Table 5).…”

“…For example, within the general area of their study, the floor of the steep-sided canyon containing the Santa Margarita River is 15 m to~50 m wide. Several tributaries, hanging 50-90 m above the floor of the canyon, dissect a broad undulating upland terrain covered by a thick section of regolith capped by Entisols, Inceptisols, and Alfisols (Knecht, 1971;Nettleton et al, 1970). These relationships suggest that the regolith exposed in the walls of the Santa Margarita River sampled by Girty et al (2013) largely formed prior to its down cutting.…”

Illite neoformation in plagioclase during weathering: Evidence from semi-arid Northeast Brazil

“…There has been sporadic discussion of clay mica being pedogenically formed under arid and semi-arid climates by conversion of a swelling clay (e.g. smectite) to a 1 nm mineral (e.g., Nettleton et al, 1970). However, such examples emphasize the transformation of one clay mineral species into another and not the neoformation of clay mica from primary rock-forming tectosilicates as demonstrated here (Figs.…”

Elemental translocation and loss from three highly weathered soil–bedrock profiles in the southeastern United States

“…Dilation may also be attributed to infilling of macropores with illuviated silt and clay-sized particles (Brimhall et al, 1991a,b), which were frequently observed on the surfaces of macropores of the Tarrus saprolite. Dilation of C horizons may also be caused by transformations of rock-forming minerals that result in expansion, for example, weathering of mica to form vermiculite (Folk et al, 1982;Nettleton et al, 1970). Considering that the Tarrus saprolite and Enon C horizon contained vermiculite or smectites, the dilation of these regoliths could be attributable to expansions of secondary minerals.…”