Marine Geophysical Reconnaissance of Continental Margin North of Paria Peninsula, Venezuela

Abstract

Marine geophysical observations north of the Paria (Venezuela) Peninsula and westernmost Trinidad have delineated three features that dominate the shallow structural pattern of the shelf: (1) Carupano Sea Valley, which extends eastward along the Paria-Araya shoreline and occupies a structural depression bounded on the south by a major fault system; (2) Cumberland Rise, a locally complex structural and topographic high north of the sea valley; and (3) Tobago Trough, which appears to extend southwest across the shelf almost to the Paria-Trinidad coast. The orientation of the positive elements of Cumberland Rise and the trend of magnetic anomalies that seem to be associated with the Carupano depression suggest that both features may be related to the Lesser Antilles arc. Det itus eroded from the Paria-Araya Peninsulas is inferred to have been transported eastward through Carupano Sea Valley into Tobago Trough; the Paria shelf has been built upward and northward by sediments which bypassed the valley and were carried directly offshore, over the Cumberland Rise, to be deposited as foreset beds on an old erosion surface. The extension of the Lesser Antilles arc southwest into the Paria-Araya shelf is marked by a +60 to +100 mgal free-air gravity anomaly. A shallow igneous intrusive extends from Los Testigos Islands northeast along the trend of this anomaly to the upper continental slope, where the intrusive is truncated by a northwest-southeast fault. The fact that the trends of the arc can be traced well into the Paria shelf militates against the presence of an east-west transcurrent fault between Carupano Sea Valley and the Grenada platform.