Tectonic setting and geochemistry of Miocene alkalic basalts from the Jones Mountains, West Antarctica

M. J. Hole, B. C. Storey, W. E. LeMasurier

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Within the Jones Mountains, which form part of the Thurston Island crustal block, uo to 700 m of Miocene (c.10 Ma) pillow basalt and palagonitized volcaniclastic rocks unconformably overlie Jurassic granitic basement and Cretaceous volcanic rocks and dykes. New geochemical analyses demonstrate the alkalic nature of the basalts, which range in composition from alkali basalt to basanite. Unradiogenic Sr-isotope ratios (0.7031-0.7034), coupled with low LILE/HFSE ratios (e.g. Th/Ta c. 1.4, Rb/Nb 0.3-0.9) indicate a predominantly asthenospheric source for the basalts. The Jones Mountains basalts are geochemically similar to the alkalic basalts of Marie Byrd Land, but have consistently lower K/Ba and higher Ba/Nb ratios than Late Cenozoic alkalic basalts along the Antarctic Peninsula. These regional variations in geochemical composition apparently reflect differences in tectonic setting and are not the result of lithospheric interaction or partial melting/crystallization effects. The generation of alkalic magmas along the Antarctic Peninsula was causally related to the formation of slab windows following ridge crest-trench collision and the cessation of subduction, whereas the Jones Mountains alkalic basalts may represent the expression of the northward propagation of the head of the Marie Byrd Land plume.

Original languageEnglish
Pages (from-to)85-92
Number of pages8
JournalAntarctic Science
Volume6
Issue number1
DOIs
Publication statusPublished - 1 Jan 1994

Keywords

  • alkali basalts
  • asthenospheric magmas
  • crustal thinning
  • plume volcanism

Fingerprint Dive into the research topics of 'Tectonic setting and geochemistry of Miocene alkalic basalts from the Jones Mountains, West Antarctica'. Together they form a unique fingerprint.

Cite this