Bowers Ridge (Bering Sea): An Oligocene-Early Miocene island arc

Wanke, Maren, Portnyagin, Maxim V., Hoernle, Kaj A., Werner, Reinhard, Hauff, Folkmar, van den Bogaard, Paul and Garbe-Schönberg, Dieter (2012) Bowers Ridge (Bering Sea): An Oligocene-Early Miocene island arc Geology, 40 (8). pp. 687-690. DOI 10.1130/G33058.1.

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Bowers Ridge is an similar to 700 km long arcuate ridge behind the Central Aleutian Arc in the Bering Sea. The lack of age and geochemical data for the ridge has hampered the development of geodynamic models for the evolution of the North Pacific and the Aleutian-Bering Sea region. Here we present the first geochemical and Ar-40/Ar-39 age data for the volcanic basement of Bowers Ridge and a seamount from the western end of the ridge sampled during R/V Sonne cruise SO201-1b. The northern Bowers Ridge basement (26-32 Ma) consists of mafic to intermediate calc-alkaline rocks with adakite-like (Sr/Y = 33-53, La-N/Yb-N = 3.3-7.8), high field strength element (HFSE)-depleted (e.g., Nb-N/La-N = 0.07-0.31) trace element patterns and Sr-Nd-Pb isotope compositions within the Western Aleutian Arc array, implying magma generation above an obliquely subducting slab. The seamount samples (22-24 Ma) are HFSE-rich alkaline olivine basalts (La-N/Yb-N = 3.3-3.9, Nb-N/La-N = 1.0-1.4) with minor arc-type trace element signatures (Pb-N/Ce-N = 1.4-1.6, K-N/Nb-N = 1.7-1.9) but with Pacific mid-oceanic-ridge basalt (MORB)-like isotopic compositions, pointing to an origin by small-degree decompression melting from slightly subduction-modified mantle. The geochemistry of the recovered rocks can be explained by highly oblique subduction along the northern part of Bowers Ridge in its present-day configuration, consistent with an in-situ origin of Bowers Ridge as a Cenozoic island arc.

Document Type: Article
Research affiliation: Kiel University
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1130/G33058.1
ISSN: 0091-7613
Projects: KALMAR, Future Ocean
Date Deposited: 20 Sep 2012 10:05
Last Modified: 17 May 2017 12:59

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