Benue Trough the Central African Shear Zone and for the volcanic island of St. Helena in the Atlantic ocean. Three periods of magmatic activity (volcanic action) have been identified, 147–106 Ma, 97–81 Ma and 68–49 Ma. The first is prominent in the north of the trough, and contemporary with magmatism in Brazil, probably occurring during a period of crustal extension before the Atlantic started to open. The second is found only in the south of the trough, and may belong to a period when the extension of the Atlantic had slowed down, ending with a period of compression. The third and last
Timor Trough Further west are the Weber Basin and Banda Trench. Oil and natural gas have been found in the Bonaparte Basin south of the trough and the region is geologically active with numerous earthquakes. Timor Trough The Timor Trough is an oceanic trough that is a continuation of the Sunda Trench that marks the boundary between Indo-Australian Plate's continental shelf and the Timor Plate to the north. It is separated from the Java Trench by a sag near Sumba Island at the Scott Plateau and North Australian Basin, and on the other end becomes Tanimbar trough southeast of the Tanimbar Islands