A PRELIMINARY ANALYSIS OF THE WOOD PRESERVATION RECOVERED FROM THE LATE CRETACEOUS COLERAINE FORMATION OF NORTHERN MINNESOTA

Fossil wood specimens collected from the Coleraine Formation along the Mesabi Iron Range of northern Minnesota are abundant and display a variety of taphonomic signatures. Hill Annex Paleontology Project volunteers have collected several dozens of samples of various sizes during the last five years of field conservation. Detailed macroscopic observations indicate a variety of preservation states ranging from evidently complete replacement by Fe-oxide/hydroxides with no original organic material or structures to what appear to be nearly unaltered original wood tissues. An investigation of the diagenetic mineralogy of the various preservation states was conducted using a variety of techniques including X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometry, and micro-X-ray fluorescence spectrometry. Macroscopic differences in preservation types are reflected in the diagenetic mineralogy observed with these techniques.