Geochemistry, Mineralogy, Volcanology Editors' Highlights

New Data from Earth’s Largest Non-Volcanic Rift Margin

Seismic reflection images combined with petrological data provide new constraints on the nature of the basement in the enigmatic Australia-Antarctic oceanic-continent transition zone.

Source: Geochemistry, Geophysics, Geosystems


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The Australia-Antarctic margin is the largest non-volcanic rift margin on Earth. Tectonic models of final lithospheric breakup of this rift system are commonly debated due to a lack of geological constraints from this remote area.

McCarthy et al. [2020] combine multi-channel seismic reflection with petrological data from dredged mantle rocks, providing new constraints on the nature of the basement in this enigmatic oceanic-continent transition zone. Their combined dataset illuminates a 50- to 100-kilometer-wide domain of fertile, cold, subcontinental mantle that was exhumed to the seafloor during rifting. Evidence for syn-rift MORB-melt crystallization at >8 kbar suggests that magnetic anomalies observed within this swath of seafloor record sparse syn-rift volcanism rather than marking the transition to steady-state seafloor spreading.

This research could anchor a range of new studies comparing the Antarctic-Australian margin to other examples such as the Jurassic Western Tethys ocean-continent transition zones.

Citation: McCarthy, A., Falloon, T. J., Sauermilch, I., Whittaker, J. M., Niida, K., & Green, D. H. [2020]. Revisiting the Australian‐Antarctic ocean‐continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle. Geochemistry, Geophysics, Geosystems, 21, e2020GC009040. https://doi.org/10.1029/2020GC009040

—Whitney Behr, Editor, Geochemistry, Geophysics, Geosystems

Text © 2020. The authors. CC BY-NC-ND 3.0
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