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
Bounty Trough Bounty Trough The Bounty Trough is a major submerged feature, a bathymetric depression, of the oceanography of the southwest Pacific Ocean. It is located off the east coast of New Zealand's South Island. It is named after the Bounty Islands near the Eastern end of the trough. The islands in turn, named after . The Bounty Trough is located to the South of the Chatham Rise, and North of the Campbell Plateau. It runs East-West for a distance of some to the deep ocean between the Chatham and Bounty Island groups. The Bounty Trough's western extremity is less than off