摘要：Layered evaporite sequences (LESs) comprise interbeddedweak layers (halite and, commonly, bittern salts) and strong layers(anhydrite and usually non-evaporite rocks such as carbonates andsiliciclastics). This results in a strong rheological stratification, with arange of effective viscosity up to a factor of 105. We focus here onthe deformation of competent intrasalt beds in different endmember modes ofsalt tectonics, even though combinations are common in nature, using acombination of conceptual, numerical, and analog models, and seismic data. Inbedding-parallel extension, boudinage of the strong layers forms rupturedstringers, within a halite matrix, that become more isolated with increasingstrain. In bedding-parallel shortening, competent layers tend to maintaincoherency while forming harmonic, disharmonic, and polyharmonic folds, withthe rheological stratification leading to buckling and fold growth bybedding-parallel shear. In differential loading, extension and the resultantstringers dominate beneath suprasalt depocenters, while folded competent bedscharacterize salt pillows. Finally, in passive diapirs, stringers generatedby intrasalt extension are rotated to near vertical and encased in complexfolds during upward flow of salt. In all cases, strong layers areprogressively removed from areas of salt thinning and increasingly disruptedand folded in areas of salt growth as deformation intensifies. The varyingstyles of intrasalt deformation impact seismic imaging of LES and associatedinterpretations. Ruptured stringers are often visible where they have lowdips, as in slightly extended salt layers or beneath depocenters, but arepoorly imaged in passive diapirs due to steep dips. In contrast, areas ofslightly to moderately shortened salt typically have well-imaged, mostlycontinuous intrasalt reflectors, although seismic coherency decreases asdeformation intensifies. Similarly, wells are most likely to penetratestrong layers in contractional structures and salt pillows, less likely inextended salt because they might drill between stringers, and unlikely intall passive diapirs because the stringers are near vertical. Thus, bothseismic and well data may be interpreted to suggest that diapirs and otherareas of more intense intrasalt deformation are more halite rich than isactually the case.
