Seismic And Radiometric Methods

Step 1: Understanding the equation.
The given equation relates the isotopic ratios of strontium ( ) to the decay of rubidium ( ) over time. The slope of the isochron line, based on the given data, can be used to calculate the age of the granitic rocks. The isochron data provides the initial ratio of ( ) and the decay constant ( ) for .
Step 2: Given data.
From the diagram, we are given:
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The age of the granite can be calculated using the equation for the slope of the isochron line.
Step 3: Calculation of age.
To calculate the age of the granite, we need to use the equation for the isochron: Where:
- is the final strontium ratio,
- is the initial strontium ratio,
- is the decay constant.
From the diagram, we use the given values and solve for the age , which yields approximately 1.05 Ga.
Step 4: Conclusion.
Therefore, the age of the granite is approximately 1.05 Ga.