Could you guys help me with my Geology Homework, “Absolute Dating of Rocks and F
ID: 154320 • Letter: C
Question
Could you guys help me with my Geology Homework, “Absolute Dating of Rocks and Fossils DATING SOME ISOTOPES USED FOR ohotog)aterials Dated Usetud Dating Range Newly formed ages 10 my ages > 10 m.y Lead-206 4.5 bilion years Zecon Uranium-235 Lead-207 713 Potassium-40 Argon-401.3 billion years milion years Zircon 15.9% decayed to daughter Biotte, muscovite, whole volcanic rock ages>50,000 yr Cabon 14 Nrogen-14 5730 years Stolt, Imeuton 100-60.000 84.1 70.7 29.3% decayed Atoms (P) 500 Atoms O 25.0 75% decayed 12.5 87.5% 6.2 3.1 93.8% 969% decayed Half-Lives (Th) Elapsed DECAY PARAMETERS FOR ALL RADIOACTIVE DECAY PAIRS Percent of Percent of Atoms C 0.0 Parent Haill-Lives Atoms (P) 1000 98.9 97.9 0.000 x T 0.015 xT 0.031 xT 16 91.7 84.1 70.7 50.0 35.4 25.0 12.5 62 3.1 0.082 x T 0.125xT 0250xTy .500*T 1,000 x T 1.500 x T 2.000 x T 8.3 15.9 50.0 64.6 75.0 875 93.8 96.9 3.000 x T 4.000 x T 5.000 x T FIGURE 8.11 Radiometric dating. Some isotopes useful for radiometric dating, their decay parameters and their useful a for dating The halif-life of each decay pair is different (top chart), but the graph and decay parameters (bottom charts) are the same for all decay pairs Dating of Rocks, Fossils, and Geologic Events 215Explanation / Answer
Answer- given- calculation for zircon grain from the mass spectrometer. the atoms contain 71% of U-235 and 29% of Pb- 207. the total number of half life elapsed in the zircon crystal is 1/2 half-life or 0.5.half life
the absolute age of lava flow on the basis of zircon is 0.500*t1/2 (half-life)
half-life of U235-Pb207 is 710 million year
= 0.500*710 = 355 million year
so the absolute age of lava flow on the basis of occurrence of zircon grain is 355 million year
the age of the rock is rock lying above the lava flow is younger than 355 million year
the age beneath the lava flow is older than 355 million years.
Answer- the oldest meteorite on the earth is Hypatia in western Egypt in 1996. and Its age is not determined til yet. another oldest meteorite on the earth Allende in 1969. its age is 4.567 billion year. Its age is not determined by U238-Pb 206, it is obtained by Ar40-Ar39
Now it given zircon is dated by U238-Pb 206 method. this zircon contain 71% U-238 and 29% Pb-206
half-life is 4.47 billion year
the age of zircon is 0.500* half-life (4.47 billion years
so age is 2.235 billion year.
if there is no half-life and according to this age of the earth is 4.47 billion year. but the actual age of the earth is 4.567 billion year.
Answer- We have assumed that the amount of C-14 is constant. C-14 is replaced in the organism when the animal died it convert into peat. It is given that peat has 6% of C-14 means it degraded up to 94%. this conversion elapsed 4half-life of C-14.
the age of the peat is = 4* half-life of C-14 = 4*5730 = 22920 year.
Answer- On dating peat bed. we have to avoid younger plant root or limestone bed lying above that because limestone gives older date than the date of peat and plant root will younger date than the date of peat bed.
Answer- ZIrcon forms in magma and cool with igneous rocks. on the acting of various physical weathering agents. it broke down and converted into detrital zircon. If we have found zircon on beach sand that zircon is detrital zircon. If we date that zircon it will never give the modern age. it gives that when zircon grain is formed.
Answer- Seller claims that the age of dinosaur bone is 400 million years ago. yeah, I will suspicious on the authenticity of the bone because first reptiles named Hylonomus appeared on the earth during the late Carboniferous period about 315 million years ago. how could he find the bone of age 400 million years