1003 … Mineral at time daa of crystallization 同位 e Atoms of parent element 素年 元SEO=0元 e Atoms of daughter element 龄测 50 ..... Mineral after 曲很你非④非 定 one half-life 25 .....-. Mineral after two half-lives 12.5 Mineral 8625 after three 3.125 half-lives 2 3 4 Time Units
同位 素年 龄测 定
8 100 Newly formed Mineral 铀铅法测年 75.0 e Uranium 238(Parent Nuclide 500 e Lead 206(Daughter Nuclide) Eo s c250+---- 12.5 + 1 half-life 2 half-lives 3 half-lives 4 half-lives 4.5 9.0 13.5 18.0 Billion Years Increasing Time Figure 5-10 Rate of radioactive decay of uranium 238 to lead 206. During each half-life, one-half of the remaining amount of the radioactive element decays to its daughter element. In this simplified diagram only the parent and daughter nuclides are shown, and the assumption is made that there was no contamination by daughter nuclides at the time the mineral formed In this conceptual diagram, the millions of atoms actually involved in the decay process cannot be depicted
铀—铅法测年
Pb214 210 Pb? 206 82 Bi214 Lead Bi 1210 铀铅 Bismuth E Po212 Polonium Po214° Po210 85 法测年 Astatine 86 ●Rn222 Radon 87 Francium 88 5 226 Radium Alpha decay step 89 Th 234 Beta decay step Actinium 户a234●Th230 Thoria 91 Protactiniu 92 U238 FIGURE 2.6 Radioactive decay series for anu233t。Lead26、Radi。 active ura un 23名 decays t。 its stabLe end p" oduct eight aLpha a d si ea steps n夏■ ferent isotopes are pr。 duced as intermediate steps in the de一 y senes
铀—铅 法测年
c的形成速率 是2个eccm2 14C dating 14C dating Cosmic radiation Nitroger 14 Cetrbon14 alse into the tissue g with Cl and of living organisms n a fairly constant ratio conerts Carbon 14 Bota decay 45,Nitrogen Beta particle op Proton D Neutron FIGURE 2.11 The carbon cycle showing the formation, dispersal. and decay i carbon 4
14C dating 14 C的形成速率 是2个/sec.cm2 14C dating
C. This beam came B. This beam came A. This was a living tree from an old house from a house when cut by us 1900 1910 1920 19301940 The ring patte match and overlap back into time 187018801890 B B Date of last ring is that of year when we cut tree 1850 1860 This date obtained by c counting back from bark of a This date obtained by counting back C from bark of A through B DE D 14C tree-ring F Specimens taken from ruins patterns dating H when matched and overlapped as indicated, progressively extend the dating back into prehistoric FIGURE 2.12 In the cross-dating method tree ring patterns from different woods are matched against each other to establish a ring-width chronology backward in time
14C & tree-ring patterns dating