Dating the marine Paleo Record (Geochronology)

Question 1

Radioisotopes

Answer 1

Have an atom that is decaying

Question 2

What are the two ways an atom can decay?

Answer 2

1. Alpha Decay

2. Beta Decay

Question 3

What is Alpha Decay?

Answer 3

Start out with a nucleus of an atom and loose an alpha particle (Helium) – change the mass of the particle and may change the chemical compound.

Question 4

What is Beta Decay

Answer 4

Start out with a nucleus of an atom and loose a beta particle (Electron) – not actually changing the mass. Just changing the atomic number which also changes the chemical compound.

Question 5

What is half-life?

Answer 5

The amount of time for half of the atoms to decay into daughters

Question 6

How does Geochronology work?

Answer 6

Use the radioactive decay to measure time.

time is measured by portion of daughter particles to parent particles.

Question 7

How do half-lives work?

Answer 7

Always reducing (through decay) the parent isotope by 50%

Question 8

What is the approximate time range U-Th dating?

Answer 8

Millions of years

Question 9

What are types of changes in earth systems can be measured with U-Th dating?

Answer 9

Sea floor spreading

Question 10

Uranium - Uranium approximate date range it covers

Answer 10

250, 000 yrs

Question 11

What types of changes can be calculated using U-U dating?

Answer 11

Ocean mixing. (Oceans take about 1,000 yrs to turn over)

Question 12

What does U-U rely on that other geochronological data does not?

Answer 12

Secular Equilibrium

Question 13

Radiocarbon Dating approximate date ranges it covers

Answer 13

Works well for the last 50,000 years.

Question 14

What are the types of short-lived radioisotopes?

Answer 14

1. Silicone 32

2. Lead 210

Question 15

What is the 1/2 life of Silicone 32?

Answer 15

153 yrs

Question 16

What is the half life of Lead 210

Answer 16

22.6 years

Question 17

How are both of the short-lived radioisotopes incorporated into sediments?

Answer 17

Both are deposited by rain and then transported to the marine environment by rivers. The sediment then falls down and gets incorporated into the seafloor.