Potentially biogenic carbon preserved in a 4.1 billion year old zircon -...
Δημοσιεύτηκε στις 26 Φεβ 2016
Although
our planet is approximately 4.5 billion years old (Ga), Earth’s fossil
record extends only to 3.5 Ga, the chemofossil record arguably to 3.8
Ga, and the rock record to 4.0 Ga. However, detrital zircons from Jack
Hills, Western Australia range in age up to nearly 4.4 Ga. From a
population of over 10,000 zircons from this locality, we identified one
4.10 Ga zircon that contains primary graphite inclusions in a crack-free
region, and report carbon isotopic measurements on the graphite.
Evidence for carbon cycling or biologic activity can be derived from
carbon isotopic studies, since a high ratio of 12C/13C is characteristic
of biogenic carbon. The 12C-rich isotopic signature of these graphite
inclusions is consistent with a biogenic origin and may be evidence that
a terrestrial biosphere had emerged by 4.1 Ga, or ~300 million years
earlier than has been previously proposed.
our planet is approximately 4.5 billion years old (Ga), Earth’s fossil
record extends only to 3.5 Ga, the chemofossil record arguably to 3.8
Ga, and the rock record to 4.0 Ga. However, detrital zircons from Jack
Hills, Western Australia range in age up to nearly 4.4 Ga. From a
population of over 10,000 zircons from this locality, we identified one
4.10 Ga zircon that contains primary graphite inclusions in a crack-free
region, and report carbon isotopic measurements on the graphite.
Evidence for carbon cycling or biologic activity can be derived from
carbon isotopic studies, since a high ratio of 12C/13C is characteristic
of biogenic carbon. The 12C-rich isotopic signature of these graphite
inclusions is consistent with a biogenic origin and may be evidence that
a terrestrial biosphere had emerged by 4.1 Ga, or ~300 million years
earlier than has been previously proposed.
Κατηγορία
Άδεια
- Τυπική άδεια YouTube
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου