The Influence of Geological Burial on the Deformation Characteristics of Bonded Carbonate Rocks

ABSTRACT: Mechanical behaviour of bonded carbonate sediments is dominated by a transition from an intact-elastic deformation regime at small strains to a ductile compression regime at larger strains. Characteristics of the transition depend upon porosity, with both the elastic limit and the transitional stress interval increasing as porosity decreases. The transitional behaviour is demonstrated using uniaxial compression experiments that define two uniaxial stress (k_o) ratios. These represent the stress conditions prevailing during one dimensional compression in the intact-elastic and ductile-compression regimes. When the sediment achieves a volume strain of about 1 %, it leaves the intact-elastic regime and makes an excursion to the ductile-compression regime where further deformation occurs. This excursion is irreversible in mechanical terms, but intergranular bonding is re-established during diagenesis causing a return to the intact-elastic regime. During its geological history, a sediment may make repeated excursions between the two states: in each excursion pore volume is lost.