Term
Isotopic dating/Geochronology dating |
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Definition
Determining the ages of rocks through their contained radioactive element. |
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The isotope of a given element has the same atomic number as the element, but a different atomic mass. |
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U-238 and U-235 are two naturally occurring isotopes of uranium. |
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Radioactive decay/radioactivity |
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Definition
The spontaneous disintegration of the nuclei of an atom. |
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Definition
The time that it takes a given amount of a radioactive isotope to be reduced by one half. |
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The constant that reflects the rate at which a radioactive isotope decays per unit of time. |
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N is the number of parent isotopes remaining at time t. |
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Term
N = No(e-/\t) for N for /\ |
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Definition
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Fundamental age equation or age equation |
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Definition
t = (1/ /\)(ln[(D/P)+1]) |
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t = (1/ /\)(ln[(D/P)+1]) for P |
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The amount of remaining original isotopic material |
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Isotope system utilized to date very young rocks and a Pleistocene tree trunk. Has the smallest half-life. |
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Definition
Used to date volcanic deposits containing a dinosaur. Used for minerals that contain element K. |
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The isotopic system with the longest half-life |
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What types of rocks are found at Jack Hills, NW Australia and why are they significant? |
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Definition
Conglomerate. Detrital zircons were eroded, transported, and then deposited as part of the conglomerate. A single detrital zircon was dated at 4.4 b.y. using the U-Pb method. |
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What isotopic system is used for minerals that contain element K? |
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Isotopic system for crystal of zircon |
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What is the oldest Earth material and how old is it? Where is it? |
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Definition
Zircon, 4.4 b.y. Jack Hills, NW Australia. |
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What, how old, and where is the oldest rock dated on Earth? |
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Definition
Acasta gneiss, 4.03 b.y., NW Canada. |
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Can you date the age of the Earth from fossils? |
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Definition
No, the first evidence for life on Earth does not occur until the Archean. In other words, there was no life on Earth until approximately 4.0 billion years ago. Without life there can be no fossils. |
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What mineral and isotopic system were used to date the oldest detrital crystal and rock on planet Earth? |
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