Carbon dating validity

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A rock, on the other hand, may contain minerals formed at more than one time under a variety of conditions.Under such circumstances the isolation and analysis of certain minerals can indicate at what time these conditions prevailed.If minerals are used for dating, the necessary checks on the ages are achieved by analyzing samples from more than one location and by analyzing different grain sizes or mineral types that respond differently to disturbing events.

The uncertainty in determining the slope is reduced because it is defined by many points.Here, a single uranium–lead isotopic analysis can provide an age more precise than can be obtained by the whole rock isochron method involving many analyses.When single minerals are analyzed, each grain can be studied under a microscope under intense side light so that alterations or imperfections can be revealed and excluded.Similar studies have shown that the samarium–neodymium (Sm–Nd) parent–daughter pair is more resistant to secondary migration but that, in this instance, sufficient initial spread in the abundance of the parent isotope is difficult to achieve.trace minerals may form, each concentrating certain elements and radioactive trace elements within the rock.By careful selection, certain minerals that contain little or no daughter element but abundant parent element can be analyzed.The progressive increase in the abundance of daughter isotopes over time gains a special significance where the parent element is preferentially enriched in either the mantle or the crust. In contrast, modern volcanic rocks in the oceans imply that much of the mantle has a value between about 0.703 and 0.705.

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