The San Martín Anticline: a classic example of a fault-bend fold in the Camisea fold and thrust belt, Central Andes, Perú

Disalvo A.; Rocha E.; Chung Ching J.F.; Doiny Cabré J.P. · Andean Structural Styles: A Seismic Atlas (2022) · DOI: 10.1016/b978-0-323-85175-6.00022-5

Resumen

The Camisea fold and thrust belt is a classic thin-skinned fold and thrust belt with five structural trends, made up of sequentially imbricated thrusts sheets. These thrusts generate several anticlines, many of which hold hydrocarbon accumulations totaling more than 25TCF and 1.3 BBC in the entire area. High-quality 3D depth-migrated seismic allows a detailed interpretation of the San Martín Anticline, which will be the focus of this work since it is a typical structure in the Camisea area. The San Martín Anticline is an excellent example of a duplex formed by imbricated fault-bend folds, with the basal detachment in the Devonian shales and the upper detachment in the lower section of the Cenozoic strata. It can be clearly interpreted, with a thrust fault plane, cutoff angle and dips of the back and frontal limbs that resemble Suppe's first mode fault-bend folds. This structure is folded by a second thrust sheet (Fitzcarraldo) and therefore a break-forward imbricate thrusting style is proposed. Additionally, high angle reverse faults with minor displacement and southern vergence are interpreted in the eastern portion of the San Martín structure. A kinematic evolution of the structure, starting from its undeformed state and reaching the final interpreted cross section, is presented in order to balance and validate the structural cross-sectional interpretation.