Gce Model Questions Vol1 2024 Geography Question 23

Practice objective / multiple choice question 23 from the 2024 Gce Model Questions Vol1 Geography examination.

Gce Model Questions Vol1 2024 Geography Objective / Multiple Choice Medium Difficulty
Question 23 GCE_MODEL_QUESTIONS_VOL1 • 2024 • GEOGRAPHY • objective

A rock sequence consists of three layers: Layer A (basalt) contains a mineral dated by the K-Ar method at 150 ± 5 Ma; Layer B (sandstone) contains a fossil that indicates a minimum age of 120 Ma; Layer C (limestone) contains a zircon grain that yields a concordant U-Pb age of 110 ± 3 Ma. Assuming no post‑depositional alteration, determine the most probable age range (in millions of years) for the deposition of the sandstone Layer B and explain any apparent discrepancy between the fossil and the radiometric ages.

Answer Options

Correct Answer A. Between 120 Ma and 150 Ma; the fossil gives a minimum age that is compatible with the radiometric ages of the adjacent layers, so no real discrepancy exists.
B. Between 115 Ma and 145 Ma; the fossil provides a maximum age, which contradicts the younger radiometric dates.
C. Between 110 Ma and 130 Ma; the fossil appears older than the radiometric ages, suggesting a discrepancy.
D. Between 130 Ma and 160 Ma; the fossil age conflicts with the radiometric ages, indicating possible reworking.
Correct Answer
A
Correct Option:
Between 120 Ma and 150 Ma; the fossil gives a minimum age that is compatible with the radiometric ages of the adjacent layers, so no real discrepancy exists.

About This Question

This is Gce Model Questions Vol1 2024 Geography Question 23. It is one of the objective questions from the 2024 Gce Model Questions Vol1 Geography examination.

Difficulty level: Medium .

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