absolute dating Flashcards
problems with radiometric dating in sed. rocks
weathering and erosion - breaks down closed system, minerals gain or lose atoms
what are symbols for potassium - argon dating
K-Ar
what are the values for K-Ar dating
40K-40Ar
which is the most widely used form of dating
K-Ar
where can you fins Potassium (k)
muscovite
biotite
hornblende
glauconite
what is half life of K
1260 Ma
K can be used to date rocks at..
the time of their crystalisation
how is K-Ar dating unique
11% of potassium decays to for Argon gas WHICH IS NOT FORMED ANY OTHER WAY
in which speed of cooling rocks is K-Ar dating most usedful
rapidly cooled rocks
problem with dating K-Ar rocks?
Ar is a gas so it can escape
which rocks (ign, sed, met,) is Ar found in?
IGNEOUS SEDIMENTARY AND METAMORPHIC
What are symbols for Rubidium - Strontium dating
Rb-Sr
what are values for Rb-Sr
87Rb-87Sr
Rb-Sr is found in which minerals
muscovite
biotite
K-feldspar
what is Rb Rubidium half life
50,000 Ma
benefits of Rb-Sr dating
Rb decays to Sr which is a SOLID so less likely to escape than Argon
best rocks to date using Rb - Sr
metamorphic rocks
which rocks can be dated with Rb-Sr
metamorphic
igneous
how can K-Ar dating be inaccurate in sedimentary rocks?
Daughter Ar is a gas so escapes so there are LESS daughter atoms and the rock is interpreted as OLDER
how can CLASTS in sedimentary rocks be an issue when it comes to K - Ar dating
can give results for a whole range of ages as the clasts are younger than the rest of the rock
problems with dating metamorphic rocks
parent and daughter atoms can be gained and lost during heating events
metamorphosis can RESET THE RADIOMETRIC CLOCK in some minerals and not others
problems in dating igneous rocks
large scale intrusions can take 10,000s years to cool, different parts reach closing temp before others
where are the most reliable igneous rock dates found
small fast cooling intrusions/extrusions
symbols for Uranium - lead dating
Ur-Pb
