Genesis of Clay Minerals

Galán, E.; Ferrell, Ray E.

doi:10.1016/b978-0-08-098258-8.00003-1

Cited by 100 publications

(56 citation statements)

References 188 publications

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“…Chester et al (1993) subdivided a fault zone into the fault core, which is a narrow zone close early in the diagenesis by the reaction with groundwater (Nesbitt & Young, 1989) The clay mineral associations identified by XRD and SEM-EDS analysis (Table 2) are evidence of alteration of the protolith, but may conceivably be the result of multiple processes. Their origin is either by direct precipi tation from solution (neoformation), transported with little or no modification (inheritance) or by transformation of one clay mineral to another (transformation) (Galán, 2006). Clay minerals form in different geological environments and the following origins will be considered in this study: subaerial weathering, diagenesis, low-grade metamorphism and hydrothermal alteration (Galán & Ferrell, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Their origin is either by direct precipi tation from solution (neoformation), transported with little or no modification (inheritance) or by transformation of one clay mineral to another (transformation) (Galán, 2006). Clay minerals form in different geological environments and the following origins will be considered in this study: subaerial weathering, diagenesis, low-grade metamorphism and hydrothermal alteration (Galán & Ferrell, 2013).…”

Section: Discussionmentioning

confidence: 99%

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Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Riber¹,

Dypvik²,

Sørlie³

2015

NJG

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As part of the recent discoveries on the Utsira High (Edvard Grieg and Johan Sverdrup fields), altered and fractured basement rocks were for the first time shown to act as a reservoir and possible migration paths for commercial hydrocarbon deposits on the Norwegian Continental Shelf. Altered basement rocks are underlying the main Upper Jurassic reservoir rocks in Johan Sverdrup and the main Cretaceous, Jurassic and Triassic reservoir rocks in Edvard Grieg. In the present study, eighteen basement cores from the Utsira High have been classified and investigated for signs of alteration, including subaerial weathering. The results show highly variable basement composition, including metasandstones, phyllites, granites, granodiorites and gabbroic rocks. In core view most of the basement rocks show signs of a medium to high degree of fracturing. Alteration has taken place in most of the cores, ranging from slight discoloration to disintegration along fractures, and to total fragmentation of the rock. The fragmentation of the rock is commonly associated with the dissolution of primary minerals and precipitation of secondary clays in the newly formed pore space. The upwards increasing disintegration and increasing amount of clay observed in the basement rocks from two of the wells (16/3-4 and 16/1-15) indicate that subaerial weathering was the main alteration agent.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Riber¹,

Dypvik²,

Sørlie³

2015

NJG

View full text Add to dashboard Cite

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“…Churchman and Gilkes (1989) noted an inverse relationship between gibbsite and kaolinite-halloysite abundances in laterites, suggesting that leaching of SiO 2 plays a prominent role in gibbsite development. Joussein (2016) and Galán (2006) observed that the proportion of halloysite to kaolinite decreases as weathering proceeds. Thus, with time, halloysite may be expected to recrystallize to kaolinite.…”

Section: Alteration Pathsmentioning

confidence: 99%

“…Neglecting gibbsite, we observe through formamide treatment that of 34 clay-bearing soils from the Hawaiian islands The occurrence of smectite-group clays is restricted to the base of the weathering profile or the rinds of core stones. Galán (2006) noted that these clays exist where base cation-rich parent rocks, high pH, high silica activity, and elevated base cations are found together. During early weathering, silica and base-cation activities are high due to the hydrolysis of feldspars and pyrox enes, and pH is elevated in relatively fresh rock.…”

Section: Alteration Pathsmentioning

confidence: 99%

“…In terms of detailed weathering paths, and excluding ash-derived Al and Fe, Galán (2006) reviewed the conditions for "kaolinitization. " This included variables for the neo-formation of halloysite to include: high precipitation rates, permeable parent rock, downward and lateral fresh water fluxes, oxidation of Fe 2+ to Fe 3+ , carbonic acid production in soil, leaching of SiO 2 , and high residual Al 3+ concentrations.…”

Section: Alteration Pathsmentioning

confidence: 99%

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A conceptual model for the rapid weathering of tropical ocean islands: A synthesis of geochemistry and geophysics, Kohala Peninsula, Hawaii, USA

et al. 2018

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Much of the world's population lives in developing countries in regions with deeply weathered soils and thick, subjacent saprolites. These areas are widespread in the tropics and compose an important component of the critical zone (CZ). The Hawaiian Islands (USA) make an excellent natural laboratory for examining the tropical CZ, where the bedrock composition (basalt) is nearly uniform but of variable age and where climate (rainfall) varies greatly. The purpose of this study is to develop a model for rapid weathering to deep regolith profiles in tropical ocean islands.In the Kohala Peninsula, Hawaii, a variably weathered, thick soil and saprolite profile is exposed along sea cliffs in a mesic climate setting. Laterite development includes the entire vadose zone, with a mineralogy that chiefly includes halloysite ± gibbsite and Fe-oxides and mixed Fe-oxides and hydroxide species developed on a 303 ka substrate. Gibbsite-rich horizons occur in enhanced zones of weathering. At the base of the weathering front and on the rinds of core stones, transient smectite clays are developed, but rapidly break down to halloysite. Excess Al and Fe found in soil and saprolite likely originated from the decomposition of volcanic ash deposited on the ground surface from later effusive volcanism.Shear-wave velocity data derived from multichannel analysis of surface waves (MASW) and common depth point (CDP) seismic reflection profiles reveal important internal details of the weathering profiles that complement information derived from nearby rock outcrop along a sea cliff. In addition to identifying the depth of the weathering front, stiff horizons within the laterite correlate to high gibbsite abundances in the MASW profile. Parallel to the paleo-lava flow direction, relict igneous stratigraphy is expressed as seaward-dipping reflectors on CDP profiles, whereas perpendicular to flow, reflector geometry suggests lenticular bodies within laterite.A synthesis of geochemistry and geophysical studies leads to the development of a conceptual model to explain variable weathering within the CZ. First, although there is an overall trend for the downward migration of the weathering front with time, zones of high initial permeability (rubble above or below a'a flows; tephra or scoria deposits) are influenced by both downward and lateral fluxes of water, leading to enhanced weathering in what are now gibbsite-rich horizons. Second, the dense cores of a'a flows with widely spaced joints preserve large core stones that weather inward where halloysite-rich saprolite gives way to smectite-rich rims. Thus, differential weathering is a natural consequence of textural variations in primary igneous stratigraphy with superimposed additions of Al and Fe from the dissolution of basaltic glass. This study shows how weathering features and processes may be synthesized from outcrop, geochemical observations, and geophysical profiles into a multi-stage conceptual model of weathering.

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Oil–water transport in clay‐hosted nanopores: Effects of long‐range electrostatic forces

2020

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Charged clay surfaces can impact the storage and mobility of hydrocarbon and water mixtures. Here, we use equilibrium molecular dynamics (MD) and nonequilibrium MD simulations to investigate hydrocarbon‐water mixtures and their transport in slit‐shaped illite nanopores. We construct two illite pore models with different surface chemistries: potassium–hydroxyl (PH) and hydroxyl–hydroxyl (HH) structures. In HH nanopore, we observe water adsorption on the clay surfaces. In PH nanopores, however, we observe the formation of water bridges because of the existence of a local, long‐range electric field. Our NEMD simulations demonstrate that the velocity profiles across the pore depend strongly on water concentration, pore width and the presence or absence of the water bridge. This fundamental study provides a theoretical basis for understanding nanofluidics with charged surfaces and can be applied in such as biological processes, chemical and physical fields, and the oil and gas extraction in clay‐rich formations.

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Genesis of Clay Minerals

Cited by 100 publications

References 188 publications

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

A conceptual model for the rapid weathering of tropical ocean islands: A synthesis of geochemistry and geophysics, Kohala Peninsula, Hawaii, USA

Oil–water transport in clay‐hosted nanopores: Effects of long‐range electrostatic forces

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