M�ron fault zone, north-central Venezuelan borderland: Identification, definition, and neotectonic character

Abstract

Location of the southern Caribbean plate boundary has been hindered mainly because it is in large part submerged. Analysis of 28 acoustic reflection profiles along the north-central Venezuelan borderland, and a review of published data, suggest that this borderland is the site of a complex fault zone, formally defined as the Moron fault zone, which encompasses the nodal region of the Bocono-Oca-El Pilar fault system. The Moron fault zone consists of: (1) an eastward extension of the Oca-Chirinos fault zone at about 10° 50′ N latitude; (2) a probable eastward continuation of the Bocono-Moron faults along the Venezuelan coast, which splits into the Avila and Macuto faults, north and east of Caracas; (3) the Tacagua fault, which is a southeastward trending splinter fault of the Oca-Chirinos fault zone; (4) and the westward extension of the Cariaco pull-apart basin and the El Pilar fault zone. All of these faults and fault zones are active, as shown by offset sea bottom, offset Pleistocene-Holocene features, and seismicity. It is suggested that the Oca-Chirinos fault zone represents a formerly more active part of the plate boundary. Since the Late Tertiary (?) or Quaternary, the Bocono fault zone was incorporated into the plate boundary, and the northwestern block (Bonaire block) was thrust northeastward over the Caribbean crust.