Primordial earth much more hospitable to life than imagined.
September 17, 2014 at 10:31 am
(This post was last modified: September 17, 2014 at 10:40 am by Anomalocaris.)
The earliest period of earth's history 4.56 billion -3.9 billion years ago, is called Hadean because for much of the history of investigation into primordial earth, no rocks were known to have survived from era and the conditions were thought to be hellish enough to destroy all traces of mineral formed during that era.
But recent advances allowed remains of mineral crystal grain zircon, formed during the Hadean, to be identified in sedimentary rocks formed after 3.9 billion years ago.
Chemical analysis of the Hadean zircon showed far from being formed in one globe spanning ocean of molten magma, the surface of the earth at the time was actually very similar to conditions today, with abundant water, mostly subdued volcanism, warm but not scoulding, probably already an active plate tectonics cycle. Although the atmosphere was warm and wet and suitable for many forms of life, it was poisonous to oxygen breathing animals.
This has two implications:
1. This seem to open the stage back up to life having first formed in benign conditions, rather than under extreme conditions like deep sea hydro thermal vents.
2. The fact that conditions on earth were benign right from the start suggests hospitality to life may be a common and natural condition for young earth like planets, and earth did not require a later coincidence of a series of unlikely events to make it hospitable.
Early earth geologically more benign than modern Iceland.
But recent advances allowed remains of mineral crystal grain zircon, formed during the Hadean, to be identified in sedimentary rocks formed after 3.9 billion years ago.
Chemical analysis of the Hadean zircon showed far from being formed in one globe spanning ocean of molten magma, the surface of the earth at the time was actually very similar to conditions today, with abundant water, mostly subdued volcanism, warm but not scoulding, probably already an active plate tectonics cycle. Although the atmosphere was warm and wet and suitable for many forms of life, it was poisonous to oxygen breathing animals.
This has two implications:
1. This seem to open the stage back up to life having first formed in benign conditions, rather than under extreme conditions like deep sea hydro thermal vents.
2. The fact that conditions on earth were benign right from the start suggests hospitality to life may be a common and natural condition for young earth like planets, and earth did not require a later coincidence of a series of unlikely events to make it hospitable.
Early earth geologically more benign than modern Iceland.