Mechanism of smectite-to-illite conversion.

Role of microbes in the smectite-to-illite reaction.

Temperature, pressure, and time have been thought to control the smectite-to-illite (S-I) reaction, an important diagenetic process used for petroleum exploration. We demonstrated that microorganisms can promote the S-I reaction by dissolving smectite through reduction of structural Fe(III) at room temperature and 1 atmosphere within 14 days. This reaction typically requires conditions of 300 d...

Compositional Variation in Component Layers in Natural Illite/smectite

-Published chemical data for suites of mixed-layer minerals from diagenetic sedimentary rocks, hydrothermally altered tufts, and a metasomatic bentonite bed indicate that the layer charge and composition of the different components of illite/smectite (I/S) differ from one geological environment to another. It appears that the composition of the elemental smectite and illite layers in the I/S is...

Porosimetry Measurement of Shale Fabric a N D Its Relationship to Illite/smectite Diagenesis

-The extent of illite/smectite (I/S) reactions is linked with quantitative measurements of shale fabric in a suite of samples from a lower Frio Formation well. Greater illitization of the I/S clays is found in laminated shales that possess a larger pore surface area/pore volume (SA/V) of 3.21 x 106 cm-~ than the adjacent massive shale lithofacies with a SA/V of 1.97 x 106 cm -~. Mean pore diame...

Composition Variation of Illite-vermiculite- Smectite Mixed-layer Minerals in a Bentonite Bed from Charente (france)

Mineralogical and chemical variations were studied in the upper half of a 1 m thick discontinuous bentonite bed interlaminated in the Lower Cenomanian sedimentary formations of the northern Aquitaine basin (France). X-ray diffraction patterns obtained from the <2 μm fraction in the Ca and K-saturated states were decomposed and compared to those calculated from decomposition parameters. They rev...

Smectite/Illite Distribution and Diagenesis in the South Timbalier Area, Northern Gulf of Mexico