-2
$\begingroup$

What kind of things are lanthanides used for in geochemical studies in terms of high temperature igneous systems and dating rocks from the earth, moon, and solar system?

$\endgroup$
3
  • 3
    $\begingroup$ What particular info did not you understand while reviewing offline and online resources about this topic? $\endgroup$
    – Poutnik
    Jan 21, 2023 at 12:09
  • $\begingroup$ Just can't seem to find anything related to high temperature igneous systems or dating $\endgroup$
    – Emma
    Jan 21, 2023 at 12:19
  • 1
    $\begingroup$ Put then enough relevant details, purpose, background and found partial confusing info in the question. Otherwise responders would be confused what exactly you want to know and especially need to know. $\endgroup$
    – Poutnik
    Jan 21, 2023 at 12:28

1 Answer 1

3
$\begingroup$

What gets used in gechemistry is not really the rare earth elements as such, but minerals containing them. The preference of these elements to for higher oxidation states (+3 or more) and relatively large size of their atoms/ions causes rare earths to be incorporated into different minerals from those that make up most of our felsic or mafic igneous rocks. An example is provided by zircons, which are used in dating rock formations by measuring their lead content versus their uranium content.

Zircons are based on zirconium orthosilicate ($\ce{ZrSiO4}$; note the +4 oxidation state of zirconium). As described in this question, the chemical composition of zircons favors inclusion of rare earth and early transition metals as they are formed. Actinide elements, also having large atoms/ions and sufficiently high oxidation states, also join in, including uranium. Lead, by contrast, is disfavored. Yet zircons are commonly found with lead, which must have emerged after the fact from radioactive decay of heavier elements, principally uranium. Given this mechanism zircons, with their rare-earth-loving formation chemistry, can be used to date the rock formations in which they appear from the amount of heavier elements (assumed to be principally uranium) that have decayed to lead since the formation of the zircon.

$\endgroup$
0

Not the answer you're looking for? Browse other questions tagged or ask your own question.