Jürgen Kropp^a, Arthur Block^a, Werner von Bloh^a Thomas Klenke^b, Hans-Joachim Schellnhuber^a

Sedimentary Geology 109, 37-51 (1997)

^aPotsdam Institute for Climate Impact Research (PIK), Telegrafenberg, P.O. Box 60 12 03, D-14412 Potsdam, Germany.

^bInstitute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, P.O. Box 2503, D-26111 Oldenburg, Germany

Abstract

Structure resulting from biogenic carbonate sedimentation of microbial mats in Recent siliclastic tidal flat sediments of the North Sea are analyzed quantitatively by a novel combination of scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM/EDX) imaging and subsequent multifractal analysis. Evaluation of calcium distribution patterns and their links to sediment-intrinsic mineralization processes show that the applied geometrical technique is an efficient tool for detecting microscopic variations in elemental distributions and related 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; and (ii) multifractal spectra are measures for the spatial inhomogeneity of authigenic calcification processes acting on the sedimentary structure. This implies that elemental distribution patterns in a sedimentary system are scale-independent phenomena. The detection of multifractal measures alsp opens a way towards a systematic survey of dynamic processes occuring in sedimentary structures.

Keywords: Early diagenesis, Carbonate cements, Microbial mats, Fractals, SEM/EDX