The origin of HIMU in the SW Pacific : evidence from intraplate volcanism in southern New Zealand and subantarctic islands
Panter, Kurt S.
Blusztajn, Jerzy S.
Hart, Stanley R.
Kyle, K. R.
McIntosh, William C.
MetadataShow full item record
KeywordContinental alkaline basalts; Mantle metasomatism; OIB; HIMU; Sr, Nd and Pb isotopes; West Antarctica; New Zealand; Lithospheric mantle
This paper presents field, geochemical and isotopic (Sr, Nd, Pb) results on basalts from the Antipodes, Campbell and Chatham Islands, New Zealand. New 40Ar/39Ar age determinations along with previous K-Ar dates reveal three major episodes of volcanic activity on Chatham Island (85-82, 41-35, ~5 Ma). Chatham and Antipodes samples comprise basanite, alkali and transitional basalts that have HIMU-like isotopic (206Pb/204Pb >20.3-20.8, 87Sr/86Sr <0.7033, 143Nd/144Nd >0.5128) and trace element affinities (Ce/Pb 28-36, Nb/U 34-66, Ba/Nb 4-7). The geochemistry of transitional to Q-normative samples from Campbell Island is explained by interaction with continental crust. The volcanism is part of a long-lived (~100 Myr), low-volume, diffuse alkaline magmatic province that includes deposits on the North and South Islands as well as portions of West Antarctica and SE Australia. All of the continental areas were juxtaposed on the eastern margin of Gondwanaland at >83 Ma. A ubiquitous feature of mafic alkaline rocks from this region is their depletion in K and Pb relative to other highly incompatible elements when normalized to primitive mantle values. The inversion of trace element data indicates enriched mantle sources that contain variable proportions of hydrous minerals. We propose that the mantle sources represent continental lithosphere that host amphibole/phlogopite-rich veins formed by plume and/or subduction related metasomatism between 500 and 100 Ma. The strong HIMU signature (206Pb/204Pb >20.5) is considered to be an in-grown feature generated by partial-dehydration and loss of hydrophile elements (Pb, Rb, K) relative to more magmaphile elements (Th, U, Sr) during short-term storage at the base of the lithosphere.
Author Posting. © The Author, 2006. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Petrology 27 (2006): 1673-1704, doi:10.1093/petrology/egl024.
Showing items related by title, author, creator and subject.
Zietlow, Daniel W.; Sheehan, Anne F.; Molnar, Peter H.; Savage, Martha K.; Hirth, Greg; Collins, John A.; Hager, Bradford H. (John Wiley & Sons, 2014-02-05)New shear wave splitting measurements made from stations onshore and offshore the South Island of New Zealand show a zone of anisotropy 100–200 km wide. Measurements in central South Island and up to approximately 100 km ...
Multibeam bathymetric surveys of submarine volcanoes and mega-pockmarks on the Chatham Rise, New Zealand Collins, John A.; Molnar, Peter H.; Sheehan, Anne F. (2011-04)Multibeam bathymetric surveys east of the South Island of New Zealand present images of submarine volcanoes and pockmarks west of Urry Knolls on the Chatham Rise, and evidence of submarine erosion on the southern margin ...
Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand Hamdan, Leila J.; Gillevet, Patrick M.; Pohlman, John W.; Sikaroodi, Masoumeh; Greinert, Jens; Coffin, Richard B. (2011-07-04)Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low ...