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

Haase, Karsten, Beier, Christoph, Fretzdorff, Susanne, Leat, P. T., Livermore, R. A., Barry, T. L., Pearce, J. A. and Hauff, Folkmar (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 . pp. 115-125. DOI 10.1016/j.chemgeo.2010.11.002.

[img] Text
2011_Haase_Hauff_etal_ChemGeo.pdf - Published Version
Restricted to Registered users only

Download (1167Kb) | Contact
[img] Other
2011_Haase_Hauff_etal_ChemGeo_SuppMat.xls - Supplemental Material
Restricted to Registered users only

Download (46Kb) | Contact

Supplementary data:

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.

Document Type: Article
Keywords: Geodynamics; Volcanology; Partial melting, mantle upwelling, incompatible elements, basalt, mid-ocean ridges
Research affiliation: Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.chemgeo.2010.11.002
ISSN: 0009-2541
Projects: Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 24 Nov 2010 13:47
Last Modified: 07 Dec 2017 13:21
URI: http://oceanrep.geomar.de/id/eprint/10116

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...