Clastic clay minerals

Various forms of macro- and microelements differ in their ability to migrate and redistribute among the soil profile. The elements contained in clastic minerals are practically immobile. The elements, bound to finely dispersed clay minerals, are either co-transported with clay particles, or are involved in sorption-desorption processes. Part of the elements are found in concretions and also in very thin coating films of hydrated iron oxides some elements make a part of specially edaphic organic compounds. 

Fine clastic sediments, mostly mudrocks, in contrast to their coarser counterparts, are either derived by first cycle weathering of silicate minerals or glass, or from recycling of older mudrocks. Physical comminution plays only a secondary role. The average shale is composed of 40-60% clay minerals, 20-30% quartz, 5-10% feldspar and minor iron oxide, carbonate, organic matter, and other components (Yaalon, 1962 Shaw and Weaver, 1965). Granitic source rocks produce shales richer in kaolinite and illite, the... 

Lynch, F. L., 1997, Frio shale mineralogy and the stoichiometry of the smectite-to-illlite reaction the most important reaction in clastic sedimentary diagenesis. Clays Clay Miner. 45 618-631. 

Thermocatalytic sulfate reduction probably is the main source of H2S in the deep subsurface (25.81). The reactions in Table II, based on the evolution of H2S and CO2 by sulfate reduction of hydrocarbons in clastic sequences where there is available SO42- (i.e. sequences with evaporite beds or cements), illustrate the importance of this process to diagenesis. Not only does it provide a diagenetic sink for Fe via pyrite, but depending on the relative availability of reactants, can either cause precipitation or dissolution of calcite and alter feldspars to clay minerals. 

Anchizone after Kibler (1964, 1968), a transitional zone between the diagenetic zone and the epizone as defined by IC mean values between 0.42 and 0.25 A°20. [Kaolinite and/or dioctahedral illite/smectite interstratified clay mineral with more than about 10% expandable layers are absent in normal clastic rocks, but they may persist in carbonate rocks, and in organic matter-rich, Na-rich and K-poor shales.]... 

Frey M (1987) Very low-grade metamorphism of clastic sedimentary rocks. In Low Temperatrrre Metamorphism. M Frey (ed) Blackie and Son Ltd, Glasgow Frey M, Robinson D (1999) Low-Grade Metamorphism. Blackwell Science, Oxford Grabb SMB, Peacor DR, Jiang W-T (1991) Transmission electron microscope observations of ilhte polytypism. Clays Clay Minerals 39 540-550... 

From these mineralogical and geochemical data we may reconstruct the formations of the Upper Silurian as potential source rocks for hydrocarbons. The widespread presence of large proportions of iUitic-kaolinitic clay minerals indicates that the Silurian sedimentation took place under relative tectonic stability and that the supply of the clastic material came from a peneplaned region with humid climate resulting in a weathering zone of illito-kaolinitic composition. 

Clastic sedimentary rocks are mainly composed of quartz, feldspar, rock fragments (lithic), clay minerals and mica. Clastic sedimentary rocks are further subdivided into conglomerates (mainly composed of rounded gravels), breccias (mainly composed of rounded... 

Clays are clastic sediments, i. e., they consist mainly of the remains of pre-existing rocks which have been broken down by weathering and/or erosion. The clay minerals are present in the form of very small particles (<0.002 mm) which have been deposited mainly in water — fresh, brackish or marine. Geologically the clays, along with shales, marls, etc., are classed as argillaceous rocks. The term "clay" is more especially reserved for material which has no pronounced bedding planes and which forms a plastic mass when wet. The principal constituents are the clay... 

Clay a group of complex silicate minerals that have sheet-like molecular structure or any clastic fragment that is less than 1/256 mm in size. 

The Wyoming deposits of Green River Formation oil shale received different stratigraphic names, but they show some striking similarities to the distribution in Colorado (9). The bottom section called the Tipton Shale Member is predominately clay-rich oil shale similar to that in Colorado. The next section, called the Wilkins Peak Member, contains dolomite-rich oil shale layers interspersed with layers of saline minerals, particularly trona, or with clastic deposits away from the depositional centers. The uppermost section, called the Laney Member, consists of dolomite-rich deposits formed during a reexpansion of ancient Gosuite Lake. 

Chelate A dissolved species, typically organic, with two or more funcHonal groups that are capable of sharing pairs of electrons with a metal caHon Clastic Material composed of pieces of pre-exisHng rocks Clay Rock or mineral with a grain size less than 4 fim (for geologists 2 /am for soil scientists), often consisHng of hydrous aluminum silicates... 

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