Magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR) provides the opportunity to probe composition of and ordering in minerals involved in the formation and alteration of sediments. MAS-NMR has the capability to detect a large number of elements, including aluminum, silicon, boron, oxygen, and magnesium. The chemical state, structural location, and with cross polarization, hydration character and surface proximity can also be determined using this method. Although MAS-NMR is relatively new and quantitative methodology is still being developed, a variety of geologic processes have been clarified through its application. Use of ²⁷Al NMR allows detailed determination of the smectite-illite transformation by monitoring the movements of aluminum in o tetrahedral positions and resultant cation ordering. Because ²⁷Al is detectable to low ppm levels, clay mineral components can be determined well below XRD detection levels. The ²⁹Si and ²⁷Al MAS-NMR have sufficient resolution to discriminate between minerals in a natural assemblage but not with the resolution of XRD. Quadrupolar nuclei such as ²⁷Al have relatively poor spectral resolution as compared to nonquadrupolar nuclei such as ²⁹Si. However, modern high field instrumentation can discriminate between most aluminum-containing minerals including aluminum oxides, hydroxides, oxyhydroxides, clays, and feldspars, as well as trace aluminum levels in quartz, cristobalite, and tridymite. The combination of ²⁷Al and ^{29 /SUP>Si NMR (and availability of other nuclei) provide a powerful aid to the resolution of exploration and production problems including determination of minor to trace amorphous components, hydration state of elements in cherts and clays, and formation damage.}

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