Question:
Which characteristic feature(s) best explain(s) the HIMU mantle reservoir?
Which characteristic feature(s) best explain(s) the HIMU mantle reservoir?
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The HIMU mantle reservoir is an important feature in understanding mantle dynamics and the isotopic evolution of Earth's mantle, particularly in oceanic basalts.
Updated On: Apr 12, 2025
- Magmas derived from this reservoir have high 208Pb/204Pb and 206Pb/204Pb
- Magmas derived from this reservoir have high 207Pb/204Pb and 206Pb/204Pb
- This reservoir has evolved with high Th/U
- This reservoir has evolved with high U/Pb
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The Correct Option is B, D
Solution and Explanation
Step 1: Understanding the HIMU Mantle Reservoir
The HIMU (High-µ) mantle reservoir is characterized by specific isotopic features:
(A) Magmas derived from this reservoir have high 208Pb/204Pb and 206Pb/204Pb: This is incorrect. The HIMU reservoir is characterized by high ratios of 207Pb/204Pb and 206Pb/204Pb, not 208Pb.
(B) Magmas derived from this reservoir have high 207Pb/204Pb and 206Pb/204Pb: This is correct. HIMU is characterized by high 207Pb/204Pb and 206Pb/204Pb ratios, which reflect the enrichment of the source in radiogenic lead.
(C) This reservoir has evolved with high Th/U: This is incorrect. The HIMU reservoir is known for having a high U/Pb ratio, not necessarily a high Th/U ratio.
(D) This reservoir has evolved with high U/Pb: This is correct. The HIMU reservoir is known for having a high U/Pb ratio, reflecting its source's enrichment in uranium relative to lead.
Step 2: Conclusion
The correct explanations for the HIMU mantle reservoir are (B) and (D).
The HIMU (High-µ) mantle reservoir is characterized by specific isotopic features:
(A) Magmas derived from this reservoir have high 208Pb/204Pb and 206Pb/204Pb: This is incorrect. The HIMU reservoir is characterized by high ratios of 207Pb/204Pb and 206Pb/204Pb, not 208Pb.
(B) Magmas derived from this reservoir have high 207Pb/204Pb and 206Pb/204Pb: This is correct. HIMU is characterized by high 207Pb/204Pb and 206Pb/204Pb ratios, which reflect the enrichment of the source in radiogenic lead.
(C) This reservoir has evolved with high Th/U: This is incorrect. The HIMU reservoir is known for having a high U/Pb ratio, not necessarily a high Th/U ratio.
(D) This reservoir has evolved with high U/Pb: This is correct. The HIMU reservoir is known for having a high U/Pb ratio, reflecting its source's enrichment in uranium relative to lead.
Step 2: Conclusion
The correct explanations for the HIMU mantle reservoir are (B) and (D).
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