( ightly integrated studies across a broa...)UCSB scientists probe sea floor venting to gain understanding of early life on Earth

For this study, Haymon and her UCSB colleagues studied the "flanks" of the mid-ocean ridge, which –?at 40,000 miles long–?is the largest geological feature of Earth, and possibly the solar system. At the mid-ocean ridge the plates comprising the Earth's lithosphere move apart, lava wells up and freezes to form rock. This is how the sea floor is created.

Haymon is interested in the large region of cooling on the sides of the mid-ocean ridge. Possibly 90 percent of the hydrothermal cooling of the sea floor occurs in these flanks, and yet these hydrothermal vents are largely unexplored. The flanks are deeper than the mid-ocean ridge crest. Cooling of the tectonic plates, and the impact of the ridge flank system on the chemistry of the ocean, are fundamental global-scale processes.

On dives in the submersible Alvin, Haymon and her UCSB colleagues –?Ken C. Macdonald, Sara B. Benjamin, and Christopher J. Ehrhardt –?studied "abyssal" underwater hills that cover a large geomorphic terrain on the ocean floor and are the most common landforms on the Earth. However, little is known about hydrothermal venting from these common features.

The team describes newly discovered geological and biological manifestations of hydrothermal activity at two sites on young abyssal hills flanking the East Pacific Rise, a fast-spreading portion of the global mid-ocean ridge system. These are the first reported manifestation of hydrothermal systems associated with abyssal hills on the flanks of a fast-spreading ridge.

"To explain these features, we suggest that abyssal hill hydrothermal venting occurs in frequent bursts, possibly triggered by earthquakes," said Haymon. "Such widespread and oft-repeated pulses of hydrothermal venting may stimulate microbial blooms on abyssal hill fault scarps, thus providing a pot
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Source:University of California - Santa Barbara