Which ONE of the following rocks shows the highest reading in the natural gamma ray log?
Show Hint
- Dolomite
- Anhydrite
- Oil Shale
- Limestone
The Correct Option is C
Solution and Explanation
Natural gamma ray logs measure the natural radioactivity of rocks, primarily due to the presence of potassium, uranium, and thorium. Among the listed rocks, {Oil Shale} typically has the highest gamma ray reading because it contains high concentrations of radioactive elements, especially uranium.
- Dolomite generally has lower gamma ray readings as it is a carbonate rock with fewer radioactive elements.
- Anhydrite also typically has lower gamma ray readings compared to oil shale.
- Limestone contains low levels of natural radioactivity as well, contributing to a relatively lower gamma ray response.
Thus, the correct answer is C, Oil Shale.
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