We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Wednesday, May 8, 2013
Ancient Earth Crust Stored in Deep Mantle
It may be possible to map this effect in other recycled volcanic
rocks worldwide and give us an indirect way to see the ancient past.
At least we now know that it is possible.
Slowly but surely we are advancing our knowledge of geological
history and piecing together an awesome history.
At the same time, we can look across at Venus and see another
prospective planet to terraform also. The surface rock temperature
remains at over 600C and will remain there until we cause the planet
to be bombarded with comets that pack plenty of of water and carbon.
That would cause the temperature to quickly collapse and set the
stage for a repeat of earth's history.
Scientists have long
believed that lava erupted from certain oceanic volcanoes contains
materials from the early Earth's crust. But decisive evidence for
this phenomenon has proven elusive.
New research from a
team including Carnegie's Erik Hauri demonstrates that oceanic
volcanic rocks contain samples of recycled crust dating back to the
Archean era 2.5 billion years ago. Their work is published in
Oceanic crust sinks
into the Earth's mantle at so-called subduction zones, where two
plates come together. Much of what happens to the crust during this
journey is unknown. Model-dependent studies for how long subducted
material can exist in the mantle are uncertain and evidence of very
old crust returning to Earth's surface via upwellings of magma has
not been found until now.
The research team
studied volcanic rocks from the island of Mangaia in Polynesia's Cook
Islands that contain iron sulfide inclusions within crystals.
In-depth analysis of the chemical makeup of these samples yielded
The research focused
on isotopes of the element sulfur. (Isotopes are atoms of the same
element with different numbers of neutrons.) The measurements,
conducted by graduate student Rita Cabral, looked at three of the
four naturally occurring isotopes of sulfur--isotopic masses 32, 33,
The sulfur-33 isotopes
showed evidence of a chemical interaction with UV radiation that
stopped occurring in Earth's atmosphere about 2.45 billion years ago.
It stopped after the
Great Oxidation Event, a point in time when the Earth's atmospheric
oxygen levels skyrocketed as a consequence of oxygen-producing
photosynthetic microbes. Prior to the Great Oxidation Event, the
atmosphere lacked ozone. But once ozone was introduced, it started to
absorb UV and shut down the process.
This indicates that
the sulfur comes from a deep mantle reservoir containing crustal
material subducted before the Great Oxidation Event and preserved for
over half the age of the Earth.
measurements place the first firm age estimates of recycled material
in oceanic hotspots," Hauri said. "They confirm the
cycling of sulfur from the atmosphere and oceans into mantle and
ultimately back to the surface," Hauri said.