Interesting geology on the sea floor

At www.sciencedaily.com/releases/2012/01/120110114434.htm there is a piece on deep sea vents in the Caribbean – with a difference (published in Nature Communications, January 10th). The vents, or deep sea hot springs we might say, are 5km down in a rift on the Caribbean sea floor. What is novel however is the discovery of 'black smokers', which are vents too, on the upper slope of an undersea mountain which rises 3km from the sea bottom. The mountain formed, it is claimed, when a vast slab of rock was twisted up out of the ocean floor. How did that happen?