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Geochemical tracing of Pacific-to-Atlantic upper-mantle flow through the Drake passage
J A Pearce1, P T Leat, P F Barker
1Department of Earth Sciences, Cardiff University, Cardiff, CF10 3YE, UK. PearceJA@cardiff.ac.uk
Nature
|March 22, 2001
Summary
Geochemical data reveal Pacific mantle outflow into the Drake Passage, driven by regional tectonics, not global mass balance. A mantle domain boundary exists between the Drake Passage and the east Scotia Sea.
Area of Science:
- Geophysics
- Geochemistry
- Earth Science
Background:
- Earth's upper mantle comprises three main reservoirs: Pacific, Atlantic, and Indian oceans.
- Pacific reservoir is contracting, while Atlantic and Indian reservoirs are expanding due to ridge and subduction zone dynamics.
- Mantle flow from Pacific to Atlantic and Indian reservoirs is proposed for mass balance, potentially through specific 'gateways'.
Purpose of the Study:
- To investigate geochemical evidence for Pacific mantle outflow through the Drake Passage.
- To determine the driving forces behind this mantle flow (regional tectonics vs. global mass balance).
- To identify mantle domain boundaries in the Southern Ocean.
Main Methods:
- Analysis of geochemical data from the Drake Passage region.
- Comparison of geochemical signatures to understand mantle reservoir interactions.
- Geodynamic modeling to assess mantle flow dynamics.
Main Results:
- Geochemical data confirm Pacific mantle outflow into the Drake Passage.
- The outflow appears to be primarily influenced by regional tectonic constraints.
- A mantle domain boundary, similar to the Australian-Antarctic discordance, is identified between the Drake Passage and the east Scotia Sea.
Conclusions:
- Pacific mantle outflow into the Drake Passage is confirmed, but driven by local tectonics.
- Global mass balance is not the primary driver for this specific mantle flow.
- The Southern Ocean exhibits distinct mantle domains separated by significant boundaries.
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