A micromechanical investigation of diagenetically-induced changes to the anisotropic elastic properties of calcareous mudstones

Abstract Microscale diagenetic changes that occur during burial exert a profound influence on the elastic and mechanical properties of sediments—but are poorly quantified. The focus here is how diagenesis influences carbonate-rich mudstones, which subject to wide range physical chemical changes. Nanoindentation data for gas-window (180 $$^\circ$$ ∘ C) Eagle Ford formation samples give intrinsic indentation moduli clay-sized calcite matrix $$M =$$ M = 40–50 GPa, contrasts with 60–77 GPa fills foraminifera tests, closer values highly crystalline calcite. weakly anisotropic. Inverse analysis immature (< 70 organic-rich chalks gives much lower biogenic calcite, between 17 30 GPa; also more anisotropic, $$M_1/M_3 \sim$$ 1 / 3 ∼ 1.3. Diagenesis, includes recrystallisation pore-filling cementation, results in becoming elastically stiffer behaving an increasingly isotropic manner, agreement grain scale studies using atomic force microscopy. demonstrate nanoindentation can resolve contributions response suggest structural addition need be accounted rock-physics models mud-rich sediments.