[extropy-chat] Deep-earth methane generation
hal at finney.org
Tue May 3 21:41:01 UTC 2005
Mike Lorrey writes:
> The real question to ask the critics of abiotic oil is: if oil ISN'T
> abiotic in origin, then how did all the dino-oil wind up UNDER the deep
> sea-floor (particularly the Gulf of Mexico, which is a pretty old
> plate), which has NEVER been above sea level, and is basaltic crust,
> not above any sedimentary layers at all? Continuing to claim that such
> oil is biotic in origin requires that one believe in Creationism for it
> to have wound up there from biotic sources.
I don't know much about the formation of oil. Are you claiming that
among geologists, there is widespread bafflement about how oil could
have ended up under the Gulf of Mexico? That this is something of an
unsolved mystery in the field? Do you want me to do research and become,
once again, an instant expert on the topic? I don't want to do it unless
you are pretty sure that this is the state of things.
I googled a bit and found one site which claims to explain the origin
of Gulf oil, http://www.lsu.edu/lsutoday/980501/pageone.html :
: The events leading up to the 1980 disaster began about 150 million years
: ago, when the nearly landlocked sea that is now the Gulf of Mexico dried
: up over and over again, said Gary Byerly, chair of LSU's Department of
: Geology and Geophysics. The evaporation of the water left huge layers
: of salt, which were eventually covered by silt and clay. Pressure from
: overlying sediments deformed the flat layers of salt into dome shapes.
: At the same time, the algae that would eventually become the oil
: and gas the Texaco rig workers were looking for were living in the
: Gulf. The climate in that period fluctuated wildly, with years so dry
: the Mississippi River would become a mud flat, followed by years of
: flash flooding, said geologist Ezat Heydari of LSU's Basin Research
: Institute. These conditions also produced great algal blooms. As the
: organisms died and drifted to the bottom, they eventually covered the
: floor of the Gulf to a depth of 500 feet or more, Heydari said. Gradually
: they became covered with silt and sank deeper and deeper into the seabed
: until they began to cook under the pressure and temperature.
: "Oil and gas are formed by thermal processes," said LSU geology professor
: Jeffery Nunn. "Organic material has to be cooked at a temperature of
: 100 degrees Celsius before it will become transformed into oil, and it
: doesn't get that hot till you get to a depth of three kilometers (almost
: 10,000 feet). It takes a long time for something to be buried that deep.
: "The oil deposits we are tapping under the Gulf of Mexico were laid down
: about 60 million years ago," Nunn said, "but even today, organisms are
: dying and falling to the bottom, continuing the process of hydrocarbon
: The salt domes and the oil deposits the rig was searching for are
: relatively recent geological phenomena. But even the earliest seas had
: a profound influence on the planet today, Byerly said.
: Byerly's field of expertise is the Archean Age, including oceans which
: formed at the dawn of time and gave rise to life on earth. "There is
: a lot of overlap between oceanography and geology. Understanding the
: ancient oceans is a major part of understanding geology," he said.
: Scientists now believe that the oceans formed shortly after the earth
: itself and have always been just about as deep and just about as salty
: as they are today. They have not become more salty over the eons, Byerly
: said, because they are constantly drying up and re-forming elsewhere,
: leaving behind great deposits of salt.
: "Scientists used to believe that the ocean basins were ancient and
: the continents were relatively young. Now we know just the opposite is
: true. Ocean basins are the most geologically active places on earth. The
: average age of the Atlantic, for instance, is between 75 and 150 million
: years. But you can find rocks 3.5 billion years old on the continents,"
: he said.
This would seem to contradict at least two of Mike's claims. The Gulf
floor is apparently only about 150 million years old, younger than
many dinosaurs; and it was indeed above water at least intermittently
during the time when the salt formations were created. There are also
apparently many sedimentary layers present. It's also worth noting that
oil is thought to be formed by aquatic life, such as algae, not dinosaurs.
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