Title Petrology, geochemistry and K-Ar age constraints of the eastern De Gerlache Seamount alkaline basalts (Bellingshausen Sea, Southeast Pacific)
Author Hagedorn, B.; Gersonde, R.; Gohl, R.; Hubberten, H.
Author Affil Hagedorn, B., Alfred Wegener Institute for Polar and Marine Research, Potsdam, Federal Republic of Germany
Source Polarforschung, 76(3), p.87-94, . Publisher: Alfred-Wegener-Institut für Polar- und Meeresforschung and Deutschen Gesellschaft für Polarforschung, Bremerhaven, Federal Republic of Germany. ISSN: 0032- 2490
Publication Date 2007
Notes In English with German summary. 50 refs. GeoRef Acc. No: 284327
Index Terms Southern Ocean--Bellingshausen Sea; Pacific Ocean--Southeast Pacific; absolute age; alkali basalts; basalts; Bellingshausen Sea; Cenozoic; chemical composition; dates; De Gerlache Seamount; East Pacific; igneous rocks; K/Ar; Miocene; Neogene; Pacific Ocean; Peter I Island; petrology; South Pacific; Southeast Pacific; Southern Ocean; Tertiary; volcanic rocks
Abstract The De Gerlache Seamounts are two topographic highs in the Bellingshausen Sea, southeastern Pacific. Petrological and geochemical studies together with K-Ar age determinations were carried out on four dredged basalt samples collected during a RV "Polarstern" expedition (ANT-XII/4) in 1995. Minor and trace element composition suggest alkaline basalt compositions. Compared to alkaline basalts of adjacent West Antarctica (the Jones Mountains) and of Peter I Island, the samples have lower mg-numbers, lower Ni and Cr contents and lower high field-strength elements (HFSE)/Nb and large-ion lithophile elements (LILE)/HFSE ratios. Three of the four samples have low K, Rb, and Cs concentrations relative to alkaline basalts. The K-depletion and other elemental concentrations may be explained by 1.1% melting of amphibole bearing mantle material. Additionally, low Rb and Ba values suggest low concentrations of these elements in the mantle source. K-Ar age determinations yield Miocene ages (20-23 Ma) that are similar in age to other alkaline basalts of West Antarctica (Thurston Island, the Jones Mountains, Antarctic Peninsula) and the suggested timing of onset of Peter I Island volcanism (~10-20 Ma). The occurrence of the DGS and Peter I Island volcanism along an older but reactivated tectonic lineation suggests that the extrusions exploited a zone of pre-existing lithospheric weakness. The alkaline nature and age of the DGS basalts support the assumption of plume activity in the Bellingshausen Sea.
Publication Type journal article
Record ID 83987