A soil micromorphology and X-ray diffraction dataset of Late Quaternary cave sediments from northeast Brazil.
Description
The dataset contains 49 soil micrographs in plane-polarized light (PPL) and 36 soil micrographs in cross-polarized light (XPL). All imagens are stored into 10 folders. The folder title means the layers of the thin section were collected. The file title flowing the general principle: the layer number comes first, then, number of the image, and finally, type of light (PPL or XPL). The micromorphological features of the cave sediments reflect the variability of soil bioturbation and bioclasts, roots channels, oxireduction conditions, and dripping water action. The relict soil microstructure varied to microgranular structure in the layers that have secondary calcium carbonate related to dripping water to massive microstructure in the lowermost thins sections. The shape and size of the orthic and anorthic nodules, quartz grains, clay coatings, voids, bones, microstructure features, etc. can be quantitatively analyzed in any image software. This dataset contains relict soil features, such as microgranular structure, runiquartz1, and iron nodules, which are features usually found in Ferralsols2.These features are present only in the layers that have speleothems, suggesting a relationship of wetter climate with speleothem deposition and Ferrasol genesis. The dataset includes 19 raw powder XRD scans. All diffractograms are stored in one XLS file organized into 2 spreadsheets. The first contains the sample ID and depth of the sampling in the trench profile. The second spreadsheet contain 19 XRD raw data. The mineralogical assemblage of primary minerals is similar across the sediment column but differs significantly by the gibbsite and kaolinite proportion. Gibbsite is absent in the lowermost layers, but peaks are strong in the upper layers, coinciding with speleothem layers and decreasing kaolinite peaks.