UCSB scientists probe sea floor venting to gain understanding of early life on Earth

February 28, 2005

New keys to understanding the evolution of life on Earth may be found in the microbes and minerals vented from below the ocean floor, say scientists at the University of California, Santa Barbara. The UCSB scientists are making new contributions to this field of inquiry in their studies of seafloor hydrothermal fluid discharge into the Earth's oceans, which has been occurring ever since the oceans first formed four billion years ago. Conditions below the sea floor may most closely mimic the environment when life began.

"There is a great deal of interest in the microbes of the Earth's crust because the strategies by which they survive may be similar to the earliest strategies of life on Earth, and perhaps also on other planetary bodies," said Rachel M. Haymon, UCSB professor of geology.

Newly discovered geological and biological manifestations of hydrothermal activity at two sites on the sea floor to the west of Central America are reported by Haymon, lead author, and three other UCSB geologists in the February issue of the journal, Geology.

The discovery of deep sea hot springs and an abundance of microbes in the subseafloor are among the most remarkable scientific findings in Earth science during the latter half of the twentieth century, and have now become a powerful motivation for research and exploration, according to the National Science Foundation, a major funder of this work. The NSF explains that subseafloor ecosystems may represent both the cradle of life on Earth and a model for the exploration and discovery of life on other planets.

"We are highly conscious of the importance of microbes in the grand scheme of things," said Haymon. "Indeed, they are the greatest biomass on the planet. They are strongly implicated as the earliest life here and perhaps elsewhere."

The direct linkages between life and planetary processes on the volcanically active, deep-sea, mid-ocean ridge system can only be understood through tightly integrated studies across a broad range of disciplines in geophysics, geology, chemistry, biology, and oceanography, according to the NSF.

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 potential food source for ridge flank biota, and an opportunity for researchers to sample the biosphere below the sea floor."

The sides of abyssal hills are fault escarpments (or scarps) created by vertical uplift of the seafloor during many events of fault slippage that produce frequent earthquakes. The scarps are cliffs that expose and provide access to the subseafloor, without the need for drilling, making it easier to tease out what is living at depth in oceanic crust. The fluids that emerge may come in bursts when earthquakes occur; fluid flow may therefore repeat episodically over hundreds of thousands of years as abyssal hills are uplifted and spread away from the mid-ocean ridge crest.

Haymon compared the subsurface microbes they found to those living in hot springs such as those at Yellowstone National Park.

Source: UCSB

Explore further: Evidence of ancient life discovered in mantle rocks deep below the seafloor

Related Stories

Jupiter's moon Europa

September 30, 2015

Jupiter's four largest moons – aka. the Galilean moons, consisting of Io, Europa, Ganymede and Callisto – are nothing if not fascinating. Ever since their discovery over four centuries ago, these moons have been a source ...

Saturn's moon Titan

October 5, 2015

In ancient Greek lore, the Titans were giant deities of incredible strength who ruled during the legendary Golden Age and gave birth to the Olympian gods we all know and love. Saturn's largest moon, known as Titan, is therefore ...

Jupiter's moon Ganymede

October 16, 2015

In 1610, Galileo Galilei looked up at the night sky through a telescope of his own design. Spotting Jupiter, he noted the presence of several "luminous objects" surrounding it, which he initially took for stars. In time, ...

The moons of Jupiter

September 15, 2015

Jupiter was appropriately named by the Romans, who chose to name it after the king of the gods. In addition to being the largest planet in our Solar System – with two and a half times the mass of all the other planets combined ...

Newly discovered ocean plume could be major source of iron

August 19, 2013

(Phys.org) —Scientists have discovered a vast plume of iron and other micronutrients more than 1,000 km long billowing from hydrothermal vents in the South Atlantic Ocean. The finding, soon to be published in the journal ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

A blue, neptune-size exoplanet around a red dwarf star

November 25, 2015

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.