The Cariaco basin, an anoxic basin in the central-eastern Venezuelan continental borderland, is located in the area of overlap of two en echelon right-lateral strike-slip fault zones, the Morón and El Pilar fault zones. On the basis of 28 acoustic reflection profiles across it, the basin is interpreted as a pull-apart basin due to east—west tension in the area of the right-step between the two ... [Show full abstract] fault zones (125 km of overlap and 35 km separation). The offset along the fault zones is less than 100 km, and at least 25 km. Its age is most probably Quaternary, as suggested by the thickness of the sedimentary fill and the estimated rate of deposition, and because strike-slip displacement along the master faults probably began no earlier than the Late Tertiary. The Cariaco basin is the largest pull-apart basin along the Boconó—Morón—El Pilar fault system which is a part of the Caribbean—South America plate boundary.