Magmatic evolution of a dying spreading axis: evidence for the interaction of tectonics and mantle heterogeneity from the fossil Phoenix Ridge, Drake Passage

Journal article
(Original article)


Publication Details

Author(s): Haase K, Beier C, Fretzdorff S, Leat P, Livermore R, Barry T, Pearce J, Hauff F
Journal: Chemical Geology
Publisher: Elsevier
Publication year: 2011
Volume: 280
Pages range: 115-125
ISSN: 0009-2541
Language: English


Abstract


New 40Ar–39Ar ages of 5.6 to 1.3 Ma for lavas from the fossil Phoenix Ridge in the Drake Passage show that magmatism continued for at least 2 Ma after the cessation of spreading at 3.3 ± 0.2 Ma. The Phoenix Ridge lavas are incompatible element-enriched relative to average MORB and show an increasing enrichment with decreasing age, corresponding to progressively decreasing degrees of partial melting of spinel peridotite after spreading stopped. The low-degree partial melts increasingly tap a mantle source with radiogenic Sr and Pb but unradiogenic Nd isotope ratios implying an ancient enrichment. The post-spreading magmas apparently form by buoyant ascent of enriched and easily fusible portions of the upper mantle. Only segments of fossil spreading ridges underlain by such enriched and fertile mantle show post-spreading volcanism frequently forming bathymetric highs. The Phoenix Ridge lavas belong to the Pacific, rather than the Atlantic, mantle domain in regional Sr–Nd–Pb space. Our new data show that the southern Pacific Ocean mantle is heterogeneous containing significant enriched portions that are preferentially tapped at low melt fractions. Isotopic mapping reveals that Pacific-type upper mantle flows eastward through Drake Passage and surrounds the subducting Phoenix Plate beneath the Bransfield Basin.



FAU Authors / FAU Editors

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik


External institutions
British Antarctic Survey
Cardiff University
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
Open University (OU)
Research Centre Juelich GmbH


How to cite

APA:
Haase, K., Beier, C., Fretzdorff, S., Leat, P., Livermore, R., Barry, T.,... Hauff, F. (2011). Magmatic evolution of a dying spreading axis: evidence for the interaction of tectonics and mantle heterogeneity from the fossil Phoenix Ridge, Drake Passage. Chemical Geology, 280, 115-125. https://dx.doi.org/10.1016/j.chemgeo.2010.11.002

MLA:
Haase, Karsten, et al. "Magmatic evolution of a dying spreading axis: evidence for the interaction of tectonics and mantle heterogeneity from the fossil Phoenix Ridge, Drake Passage." Chemical Geology 280 (2011): 115-125.

BibTeX: 

Last updated on 2018-05-07 at 06:23