William Atkins
Friday, 28 November 2008 22:26
Science -
Climate
Page 2 of 3
The episodes ended about three billion years ago, and are not expected to occur again, according to Davies.
Davies stated,
“The effect is caused by basaltic oceanic crust that is carried deep into the Earth as tectonic plates sink into the Earth’s mantle. The basaltic crust is a little denser than the mantle at most depths, but is lighter within a small depth range about one third of the way down.” [ScienceAlert: “
Old Earth bottled up magma heat ”]
He added,
“The foundered crust tends to accumulate at this depth and, if enough of it collects, can form a ‘basalt barrier’ that prevents deeper mantle material from rising to the surface where it can cool.” [ScienceAlert]
Davies stated,
“The deeper mantle is then slowly heated by radioactivity. Eventually it gets hot enough to break through the barrier and rises in a rush. It melts as it reaches the lower pressures near the top of the mantle and the melted rock erupts as lava flow. The lava flows could pile up to a thickness of ten to fifteen kilometres over much of the Earth.” [ScienceAlert]
“The episodes happened about every hundred million years so the bacteria would have had plenty of time in between to recover. Eventually, as the Earth’s interior slowly cooled, the tectonic plates became thick and heavy enough to break through the basalt barrier and prevent it from reforming, and no further episodes occurred.” [ScienceAlert]
The research performed by Dr. Davies helps to advance the scientific theory about how the continents now present on modern Earth were first formed two to three billion years ago.
The abstract to his paper goes into further detail about the ancient volcanism that occurred on Earth.
Read page three for these details on Davies' research.
