When scientists discovered a vent site in the Aurora system, they didn't know how exciting it was.
Chris German, senior scientist with the Woods Hole Oceanographic Institute's Department of Geology and Geophysics, said that the vent site they found was one of the least interesting types of vent sites that there are. We came back from the expedition thinking we found a site in the north. If you remove the ice-cover, it's just another vent site.
German and other researchers think this is a very significant finding after further analysis. They believe that this vent and others still to be located within the Gakkel Ridge rift-valley floor could change our understanding of ultra- slow spreading mid-ocean ridges and potentially expand the estimates of valuable marine mineral deposits.
There are implications for ultra- slow ridge cooling, global marine mineral distributions, and the diversity of geologic settings that can host abiotic organic synthesis.
German said that the vent site beneath the ice covered ocean is a great place to study organic synthesis relevant to the origin of life and the search for life beyond Earth. The chemistry of the overlying water column and the geology of the seafloor give us insight into the vent site and reveal its special qualities.
He said that the vent site could be used to prepare for exploring the moons of Enceladus, Jupiter's moon, and other Solar System bodies with oceans that could provide conditions for life.
According to German, the advancement in our understanding about minerals is significant.
The high levels of copper and gold present in the deposits suggest that they could be economically viable in the future.
Previously, this class of vent sites had been dismissed as unable to sustain the growth of large mineral deposits. Scientists used to think that small volcanic systems couldn't grow large mineral deposits.
German said that scientists should give the information to the International Seabed Authority so that they can make better decisions with a better understanding of the natural world.
There is an extensive field of relict mineral deposits associated with a neovolcanic mound located on the Gakkel Ridge. Researchers found that the site is more than 100 meters across. According to the paper, that is large for a volcanically hosted vent on a slow spreading ridge and is comparable to a system that requires large heat fluxes over a long period of time.
The basalt-hosted "black smoker" vents have lower dissolved methane values than Aurora's. The plumes resemble high- temperature ultramafic-influenced vents at slow spreading ridges.
The paper suggests that deep-penetrating fluid circulation may have sustained the long vent at the Aurora field. The pillow basalts seen in outcrops at the seafloor may only represent a thin veneer of oceanic crust.
Similar to meteorites, ultramafic rocks are primitive rocks from the Earth's interior. North America and Europe are spreading apart at a faster rate than the Pacific Ocean.
The significance of the Aurora discovery is that it may add a crucial new data point on what is currently a very sparse chemical plot of these types of hot springs.
Most black smokers interact with basaltic or more silica-rich rock types on the seafloor. Despite heated seawater circulation in iron-rich mantle, we only have chemical compositions for less than a dozen hot springs.
Our understanding of what happens in systems that emit fluids that differ widely from each other has been changed by the few systems we know of. There is a similarity between Aurora's plume and another hot spring, but we have not learned much about the new site. If Aurora fits into the chemical plot that we know or expands it, it will be very exciting.
Vera Schlindwein is interested in the high- temperature vent at Aurora. A professor at the Alfred-Wegener-Institute Helmholtz Center for Polar and Marine Research said that the basalt mound is at a strange location. The southern part of the Gakkel Ridge is called the Lena Trough.
A heat and melt source sufficient to build the Aurora basalt mound and sustain high- temperature vent is more of a surprise. With their highly discontinuous melt supply, ultra slow spreading ridges could hold even more surprises in store.
German said that they were surprised by how diverse the seafloor is. We get surprised when we explore because we don't just find the same things. We are finding new things that are different from what we have seen before.
There are indications of ultramafic influence at the Aurora field on Gakkel Ridge. There is a DOI of 10.1038/s41467-022-3-4014-0.
Journal information: Nature Communications
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