Petrology and isotopic composition of Quaternary basanites dredged from the Bering Sea continental margin near Navarin Basin

Saved in:
Online Access: Get full text
doi: 10.1139/e93-081
Authors:Davis, Alicé S.; Gunn, Susan H.; Gray, Leda-Beth; Marlow, Michael S.; Wong, Florence L.
Author Affiliations:Primary:
U. S. Geological Survey, Menlo Park, CA, United States
Volume Title:Canadian Journal of Earth Sciences Revue Canadienne des Sciences de la Terre
Source:Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 30(5), p.975-984. Publisher: National Research Council of Canada, Ottawa, ON, Canada. ISSN: 0008-4077
Publication Date:1993
Note:In English with French summary. 37 refs.; illus. incl. 4 tables, sketch map
Summary:These basanites are highly vesicular flow rock and hyaloclastites similar to other alkalic volcanic rocks erupted during the late Cainozoic on islands in this area and in mainland Alaska. K-Ar ages indicate volcanism at approx 1.1 and 0.4 m.y. Similar alkalic volcanism has occurred sporadically at widely separated places in the area for at least the last 6 m.y. Chemically, the alkalic lavas are intraplate basalts similar to those of oceanic islands and in some continental settings. Trace element data indicate that the lavas were generated by small amounts of partial melting of a metasomatized lherzolite source. The relatively primitive compositions, presence of mantle-derived xenoliths in some alkalic lavas, and presence of forsteritic olivine with low CaO and high NiO suggest that magma rose rapidly from great depth. Although lavas from different volcanic centres in the Bering Sea region are similar in many respects, isotopic compositions indicate heterogeneities in the source. The Navarin basanites have higher87Sr/86Sr and lower 143Nd/144Nd than any other lavas so far reported from this region. The 207Pb/204Pb ratios suggest involvement of a crustal component, which may have resulted from metasomatism associated with subduction-related magmatic activity during the early Eocene. Although some volcanic episodes seem to have occurred synchronously at widely separated centres, no large-scale regional extension nor presence of large mantle plumes are indicated. Instead, alkalic volcanism apparently resulted from upwelling and decompressional melting of small isolated mantle diapirs in response to local lithospheric attenuation associated with jostling of blocks during adjustment to regional stresses. [R.E.S.]
Subjects:Absolute age; Alkalic composition; Alkaline earth metals; Basanite; Cenozoic; Continental margin; Dates; Diapirism; Dredged samples; Geochemistry; Igneous rocks; Intraplate processes; Isotope ratios; Isotopes; K/Ar; Lava; Lead; Lithogeochemistry; Major elements; Mantle; Metals; Nd-144/Nd-143; Neodymium; Pb-207/Pb-204; Petrography; Quaternary; Radioactive isotopes; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Trace elements; Upwelling; Volcanic rocks; Volcanism; Alaska; Bering Sea; East Pacific; Navarin Basin; North Pacific; Northeast Pacific; Pacific Ocean; United States; West Pacific
Coordinates:N583900 N583900 W1771254 W1771254
Abstract Numbers:94M/3293
Record ID:1993043551
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Tags: Add Tag
No Tags, Be the first to tag this record!