Adult xxx dating sim game - U pb isotope dating

First of all, uranium will readily substitute for the zirconium (Zr) in the mineral, whereas lead is strongly rejected.For this reason we expect zircons, when formed, to contain some uranium, but virtually no lead.

u pb isotope dating-47

Now since all rocks are somewhat porous, and since we are pretty much obliged to date rocks from near the surface, it's hard to find instances in which uranium has not been lost.

; as you can see from its chemical formula, it is one of the silicate minerals.

Uranium can and often does substitute for the element yttrium, whereas lead cannot, making xenotime suitable for radiometric dating.

The key fact about xenotime is that since it has the same crystal structure as zircon, it can grow on zircon crystals, forming a crust; and this process, of course, cannot begin to take place while the zircon crystal is still locked inside its parent rock.

Now, compounds of uranium are often highly soluble in water (this, indeed, is one of the major problems with U-Pb isochron dating) whereas compounds of lead are stubbornly insoluble.

As a result, we expect speleothems when they are first formed to contain some uranium but little or no lead — just like zircons.There is a difficulty in using radiometric dating to put an age on sedimentary rock.The problem is that sediment is made up of clasts of some parent rock, and when we date these clasts, we are in effect dating the parent rock rather than the sediment as such.The zircon will only start acquiring its xenotime crust after weathering and erosion have freed it from its parent rock and it becomes sediment.So by dating the xenotime crust, we can find out when the zircon it's growing on became sediment; dating the zircon itself would tell you the age of the parent rock.Pb (lead-204), which is neither unstable nor radiogenic.

Tags: , ,