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TABLE 1. Results of Isotopic Analyses: Rock Unit A B C Number of Parent Atoms Number of Daughter Atoms 7497 1071 11480 3827 839 2517 Radioactive parent isotopes decay at a constant rate and slowly become stable daughter isotopes. The decay rate is stated in terms of half-lives: the time it takes for one-half (50%) of the parent isotope to decay into the daughter isotope is called the half-life. As the rock ages, the amount of the parent isotope will decrease and the amount of the daughter isotope will increase geometrically (not linearly). Graphs of radioactive decay clearly show this geometrical or exponential decay. To determine the age of an unknown rock, you need to measure the number of parent and daughter atoms in a sample (this data is given to you in the table). The ratio of the daughter atoms to the parent atoms is proportional to the age. But if you know the half-life as well as the number of atoms of both isotopes, you can calculate the age in years-an absolute age. You need to use the following formula: R - Po (R+D) P% is the percent of initial parent atoms remaining in the system Po is the number of parent atoms originally present when the rock formed Pt is the number of parent atoms today (see table) D+ is the number of daughter atoms today (see table). Obviously, the total of the parent and daughter atoms today is equal to the number of parent atoms when the rock formed, since each daughter atom came from a parent atom. When you divide the number of parent atoms today by the number of parent atoms originally, you will get a ratio, such as 1/4 (= 25%) or 1/2 (= 50%). This ratio is the percent of parent atoms remaining in the system today, and is directly related to the number of half-lives that have transpired since the rock crystallized from magma. Please answer the following questions. Please show all your work: write your equations, values, and calculations. 1. What is the absolute age of the basaltic dike, unit A? 2. What is the absolute age of the granite, unit B? 3. What is the absolute age of the folded metamorphic rock, unit C? 4. Compare your measured ages to the initial chart. If you were to use the principles of relative dating, would the order of the observed layers make sense? Explain using the principles in your answer.

TABLE 1. Results of Isotopic Analyses: Rock Unit A B C Number of Parent Atoms Number of Daughter Atoms 7497 1071 11480 3827 839 2517 Radioactive parent isotopes decay at a constant rate and slowly become stable daughter isotopes. The decay rate is stated in terms of half-lives: the time it takes for one-half (50%) of the parent isotope to decay into the daughter isotope is called the half-life. As the rock ages, the amount of the parent isotope will decrease and the amount of the daughter isotope will increase geometrically (not linearly). Graphs of radioactive decay clearly show this geometrical or exponential decay. To determine the age of an unknown rock, you need to measure the number of parent and daughter atoms in a sample (this data is given to you in the table). The ratio of the daughter atoms to the parent atoms is proportional to the age. But if you know the half-life as well as the number of atoms of both isotopes, you can calculate the age in years-an absolute age. You need to use the following formula: R - Po (R+D) P% is the percent of initial parent atoms remaining in the system Po is the number of parent atoms originally present when the rock formed Pt is the number of parent atoms today (see table) D+ is the number of daughter atoms today (see table). Obviously, the total of the parent and daughter atoms today is equal to the number of parent atoms when the rock formed, since each daughter atom came from a parent atom. When you divide the number of parent atoms today by the number of parent atoms originally, you will get a ratio, such as 1/4 (= 25%) or 1/2 (= 50%). This ratio is the percent of parent atoms remaining in the system today, and is directly related to the number of half-lives that have transpired since the rock crystallized from magma. Please answer the following questions. Please show all your work: write your equations, values, and calculations. 1. What is the absolute age of the basaltic dike, unit A? 2. What is the absolute age of the granite, unit B? 3. What is the absolute age of the folded metamorphic rock, unit C? 4. Compare your measured ages to the initial chart. If you were to use the principles of relative dating, would the order of the observed layers make sense? Explain using the principles in your answer.

Applications and Investigations in Earth Science (9th Edition)
Applications and Investigations in Earth Science (9th Edition)
9th Edition
ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Chapter1: The Study Of Minerals
Section: Chapter Questions
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TABLE 1. Results of Isotopic Analyses: Rock Unit A B C Number of Parent Atoms Number of Daughter Atoms 7497 1071 11480 3827 839 2517 Radioactive parent isotopes decay at a constant rate and slowly become stable daughter isotopes. The decay rate is stated in terms of half-lives: the time it takes for one-half (50%) of the parent isotope to decay into the daughter isotope is called the half-life. As the rock ages, the amount of the parent isotope will decrease and the amount of the daughter isotope will increase geometrically (not linearly). Graphs of radioactive decay clearly show this geometrical or exponential decay. To determine the age of an unknown rock, you need to measure the number of parent and daughter atoms in a sample (this data is given to you in the table). The ratio of the daughter atoms to the parent atoms is proportional to the age. But if you know the half-life as well as the number of atoms of both isotopes, you can calculate the age in years-an absolute age. You need to use the following formula: R - Po (R+D) P% is the percent of initial parent atoms remaining in the system Po is the number of parent atoms originally present when the rock formed Pt is the number of parent atoms today (see table) D+ is the number of daughter atoms today (see table). Obviously, the total of the parent and daughter atoms today is equal to the number of parent atoms when the rock formed, since each daughter atom came from a parent atom. When you divide the number of parent atoms today by the number of parent atoms originally, you will get a ratio, such as 1/4 (= 25%) or 1/2 (= 50%). This ratio is the percent of parent atoms remaining in the system today, and is directly related to the number of half-lives that have transpired since the rock crystallized from magma. Please answer the following questions. Please show all your work: write your equations, values, and calculations. 1. What is the absolute age of the basaltic dike, unit A? 2. What is the absolute age of the granite, unit B? 3. What is the absolute age of the folded metamorphic rock, unit C? 4. Compare your measured ages to the initial chart. If you were to use the principles of relative dating, would the order of the observed layers make sense? Explain using the principles in your answer.
Transcribed Image Text:TABLE 1. Results of Isotopic Analyses: Rock Unit A B C Number of Parent Atoms Number of Daughter Atoms 7497 1071 11480 3827 839 2517 Radioactive parent isotopes decay at a constant rate and slowly become stable daughter isotopes. The decay rate is stated in terms of half-lives: the time it takes for one-half (50%) of the parent isotope to decay into the daughter isotope is called the half-life. As the rock ages, the amount of the parent isotope will decrease and the amount of the daughter isotope will increase geometrically (not linearly). Graphs of radioactive decay clearly show this geometrical or exponential decay. To determine the age of an unknown rock, you need to measure the number of parent and daughter atoms in a sample (this data is given to you in the table). The ratio of the daughter atoms to the parent atoms is proportional to the age. But if you know the half-life as well as the number of atoms of both isotopes, you can calculate the age in years-an absolute age. You need to use the following formula: R - Po (R+D) P% is the percent of initial parent atoms remaining in the system Po is the number of parent atoms originally present when the rock formed Pt is the number of parent atoms today (see table) D+ is the number of daughter atoms today (see table). Obviously, the total of the parent and daughter atoms today is equal to the number of parent atoms when the rock formed, since each daughter atom came from a parent atom. When you divide the number of parent atoms today by the number of parent atoms originally, you will get a ratio, such as 1/4 (= 25%) or 1/2 (= 50%). This ratio is the percent of parent atoms remaining in the system today, and is directly related to the number of half-lives that have transpired since the rock crystallized from magma. Please answer the following questions. Please show all your work: write your equations, values, and calculations. 1. What is the absolute age of the basaltic dike, unit A? 2. What is the absolute age of the granite, unit B? 3. What is the absolute age of the folded metamorphic rock, unit C? 4. Compare your measured ages to the initial chart. If you were to use the principles of relative dating, would the order of the observed layers make sense? Explain using the principles in your answer.
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