Friday, January 6, 2012

Black smokers and deep-sea hydrothermal vents

Recently, scientists who steered a remotely-operated vehicle (ROV) to explore deep-sea hydrothermal vents near Antarctica in 2010 published their remarkable findings in the journal of the Public Library of Science -- Biology (aka PLoS Biology).

This article from the Washington Post describes the findings in "popular media" terminology; here is the report of the actual team that was published in PLoS Biology.

Deep-sea hydrothermal vents are fascinating features and may hold important clues about the ancient history of the earth. They emit water from beneath the deep ocean floor that can be extraordinarily hot -- in some cases as hot as 464° C (over 867° F).

How can water even get that hot? Since we generally have the understanding that water boils at 100° C (or 212° F), we might think water cannot possibly get so hot, until we remember our high-school science class lesson about the fact that boiling temperature changes with pressure.

At lower pressures, water boils at lower temperatures (that's why you can get water to reach a boiling point more quickly when you go up to the mountains, and why you need a pressure suit if you take your body even higher in the atmosphere where the pressure is lower -- if the pressure gets low enough, your own body heat can cause your blood to boil for you).

On the other hand, as pressure increases, the boiling point gets higher. Down deep beneath the ocean where these deep-sea hydrothermal vents are found, the pressure is very high. Beneath the ocean floor, where the water is coming from, the pressure is even higher.

Walt Brown explains that the water that was trapped beneath the crust prior to the flood event (when most of it escaped violently, leading to events that would radically reshape the surface of our globe) was under enormous pressure. At enough pressure, that water reaches something called a "critical point" -- the point at which it will no longer boil. At or above that point, water is known as "supercritical water," incredibly hot and in a form that is something like a liquified gas:
At a pressure of one atmosphere—about 1.01 bar or 14.7 psi (pounds per square inch)—water boils at a temperature slightly above 212°F (100°C). As pressure increases, the boiling point rises. At a pressure of 3,200 psi (220.6 bars) the boiling temperature is 705°F (374°C). Above this pressure-temperature combination, called the critical point, water is supercritical and cannot boil. The initial pressure in the 10-mile-deep subterranean chamber was about 62,000 psi (4,270 bars)—far above the critical pressure. After about a century of tidal pumping, the subterranean water exceeded the critical temperature, 705°F.
This concept of supercritical water is important for understanding other clues on earth, such as the amounts of salt left by the flood, and the amount of limestone on the earth (supercritical water dissolves and holds much more of the chemicals that make up these substances than regular water can). It also helps us to understand the phenomenon of deep-sea hydrothermal vents.

Dr. Brown's hydroplate theory starts with the assumption of water trapped under the earth's surface, which became super-critical water (SCW) under great pressure. The violent escape of this water triggered a global flood. Before that initial breach, however, this supercritical water would have dissolved its way into the rock above and below the trapped water, creating a honeycomb of porous rock where it did so. According to Dr. Brown's theory, the vents deep beneath the ocean that are still spewing super-critical water today represent leftover water that remained in this porous rock at certain places on earth (there is some water remaining below the continents as well, but it is not as likely to spurt out, because there are continents on top of it, unlike that at the bottom of the oceans).

Dr. Brown explains this dissolving process, and how it may be related to the formation of deep-sea hydrothermal vents, as follows:
Quartz was one of the first minerals to dissolve. This opened up tiny grain-size pockets totaling 27% of the volume of granite. Other minerals undoubtedly also dissolved, so the chamber floor and ceiling must have looked like rigid sponges—each a few miles thick. [An interesting ancient writing touches on this. See the quote from The Book of the Cave of Treasures on page 451.] Trapped SCW that filled these tiny pockets remains today. In fact, in 2008, SCW was discovered two miles under the Atlantic floor. Scientists were shocked at finding the first naturally occurring SCW.48 This vast, steady source of superhot water, thick with dissolved minerals (and sometimes hydrocarbons49), is jetting up through the ocean floors as black smokers. [See Figure 56.]
A "black smoker" is the term often used for these vents, especially when minerals dissolved in the super-critical water precipitate out when that water vents out into the extremely cold deep ocean water, forming tall black "smokestacks."

These deep-sea vents are often the home of extremely strange and unique life forms. As the Washington Post article above explains, scientists have discovered huge six-foot worms living next to black smokers, and the image above shows a black smoker located in the Endeavor Main Thermal Area near the Juan de Fuca undersea ridge (at depths of 1200 meters to 1900 meters, or about 3900 feet to over 6200 feet) with a crowded colony of red-gilled tube worms in the foreground. The new Antarctic vents described in the articles and reports above appear to be the home of many new and previously-unknown species, including new species of kiwa crabs, barnacles, and snails (but none of the worms so common at other deep-sea vents).

The species that live near these hydrothermal vents typically eat the bacteria that feed on the chemicals that the vents spew out in the scalding-hot water -- making their food chain non-dependent on solar radiation the way ours is and the way the food chain is for all other known species on earth, according to most scientists.

The conventional explanation for these deep-sea thermal vents involves water that is somehow heated by "geothermal" heat, but although the earth's crust does contain a great amount of heat, the mechanism by which water would become heated to a super-critical temperature is not well accounted-for in the conventional explanation. This is because, in order to get to those temperatures, the water must be under tremendous pressure, and in order to get water to that tremendous pressure, the water must be in a sealed pressure chamber. Water cannot just "seep in" to an open chamber and get pressurized to the levels needed to go super-critical. Dr. Brown explains:
According to evolutionary geology, water not in a closed container seeps down against a powerful increasing pressure gradient a few miles below the ocean floor. There, magma (molten rock) heats the water to these incredible temperatures, forcing it back up through the floor. (SCW could not form by such a process, because of the two conditions highlighted in bold above. Uncontained liquid water, heated while slowly seeping downward, would expand, rise, and cool, long before it became supercritical.) Figure 55 gives a simple explanation. Besides, if the evolutionary explanation were true, the surface of the magma body would quickly cool, form a crust, and soon be unable to transfer much heat to the circulating water. (This is why people can walk over magma days after a crust has formed. The crust insulates the hot magma.) However, black smokers must have been active for many years, because large ecosystems (composed of complex life forms such as clams and giant tubeworms) have had time to become established around the base of smokers.
Thus, the bizarre world of deep-sea hydrothermal vents may be another clue that supports the hydroplate theory. It is certainly another mysterious phenomenon which the conventional theory has difficulty explaining, but which the hydroplate theory explains quite satisfactorily.

Hat tip to the "Articles Desk" section of the Graham Hancock website, where I found the link to the Washington Post article describing the new discoveries at the Antarctic deep-sea vents.