Continental Groundwater Flow: Great Artesian Basin.
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Transcript of Continental Groundwater Flow: Great Artesian Basin.
Continental Groundwater Flow: Great Artesian Basin
Great Artesian Basin 2
Great Artesian Basin 3
Great Artesian Basin 4
Great Artesian Basin 5
Western edge ~1.4Ma-old water
(ages in ka)
Cl-36 Isotope dating technique36Cl made by interaction of cosmic rays with 40Ar
in atmosphere (40Ar is ~1% of atmosphere). Nuclear Reaction:
40Ar + cosmic ray energy = 36Ar + 4He
36Cl decays to 36Ar with a halflife of 310,000yr36Cl incorporated into rainwater, but not made
by nuclear reactions in Earth’s interior.Rainwater seeps into ground, where 36Cl
decays slowly away…Amount of remaining 36Cl can be used to date
time since rainfall at surface.
Great Artesian Basin 6
Water moves through basin at ~1-5m/yr, flow-through time of ~1Ma
Great Artesian Basin 7=4
Great Plains (same type of tale)
Great Plains 2
Great Plains 3
Great Plains 4
Implication: water at Boon’s Lick came from Rockies…