Plain Language Summary
Geological samples have a wide range of heterogeneity at different sampling and analytical scales. Cores are usually analyzed after plugging, cutting, and/or crushing which will lead to the issues of inability of studying, and altering, the heterogeneity at the decimeter-scale. This study investigates the areal heterogeneity of mineral compositions, pore structure, and organic matter composition on two sub-dm-sized samples from an outcrop of Eagle Ford Shale. Complementary and integrated approaches of X-ray fluorescence for microscale mapping, (ultra-) small-angle x-ray scattering for pore structure characterization of pore diameters at 1-1000 nm, and wide-angle X-ray scattering for mineral types, in addition to thin section petrography, field emission-scanning electron microscopy, X-ray diffraction, total organic carbon analyses, and pyrolysis, were utilized to investigate the spatial heterogeneity of pore types, mineral and organic matter compositions to derive the correlation of porosity distribution and sedimentary features. This work illustrates the capabilities of relatively quick and non-destructive sampling of dm-scaled sizes and analytical scales of μm-cm for areal heterogeneity studies of natural rocks in various geophysical applications.