Question

You are asked to date a sample from a basaltic lava flow. A feldspar crystal from the basalt sample contains 350 parent isotopes of 40K and 350 daughter isotopes 40Ar. Calculate the age of the feldspar crystal in the lava flow (in Ma or Ga) using the isotopic proportions. The half-life for 40K - 40Ar is 1.3 billion. Show all your calculation steps:

Answer: The age of the basalt lava flow is ________________.

Answer 1

The feldspar crystal from the basaltic lava flow is approximately 1.3 billion years old, calculated based on the equal ratio of parent to daughter isotopes of potassium-40 and argon-40 and the half-life of potassium-40.

Step-by-step explanation:

The age of the feldspar crystal in the lava flow can be determined using the ratio of parent isotopes (40K) to daughter isotopes (40Ar) and the half-life of 40K.

Since the sample contains an equal number of parent and daughter isotopes (350 each), it indicates that one half-life has passed.

With the half-life of 40K being 1.3 billion years, we can determine that the feldspar crystal is approximately 1.3 billion years old.