MULTIFRACTAL CHARACTERIZATION OF MICROBIALLY INDUCED MAGNESIAN CALCITE FORMATION IN RECENT TIDAL FLAT SEDIMENTS

Structures resulting from biogenic carbonate cementation of microbial mats in Recent siliciclastic tidal flat sediments of the North Sea are analyzed quantitatively by a novel combination of scanning electron m icroscopy and energy-dispersive X-ray spectrometry (SEM/EDX) imaging a nd subsequent multifractal analysis. Evaluation of calcium distributio n patterns and their links to sediment-intrinsic mineralization proces ses show that the applied geometrical technique is an efficient tool f or detecting microscopic variations in elemental distributions and rel ated minerals within sedimentary matrices. Two main conclusions can be drawn: (i) magnesian calcite is a rapidly formed product of the early diagenesis of organic matter in Recent bioactive marine sediments; an d (ii) multifractal spectra are measures for the spatial inhomogeneity of authigenic calcification processes acting on the sedimentary struc ture. This implies that elemental distribution patterns in a sedimenta ry system are scale-independent phenomena. Processes causing such patt erns have occurred over certain periods with varying rates and on diff erent scales. The detection of multifractal measures also opens a way towards a systematic survey of dynamic processes occurring in sediment ary structures.