Radiometric ages for basement rocks from the Emperor Seamounts, ODP Leg 197

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doi: 10.1029/2004GC000704
Author(s): Duncan, Robert A.; Keller, Randall A.
Author Affiliation(s): Primary:
Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 5(8), 13p. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. Accessed on Sept. 13, 2004. 21 refs.; illus., incl. 1 table, sketch map
Summary: The Hawaiian-Emperor seamount chain is the "type" example of an age-progressive, hot spot-generated intraplate volcanic lineament. However, our current knowledge of the age distribution within this province is based largely on radiometric ages determined several decades ago. Improvements in instrumentation, sample preparation methods, and new material obtained by recent drilling warrant a reexamination of the age relations among the older Hawaiian volcanoes. We report new age determinations (40Ar-39Ar incremental heating method) on whole rocks and feldspar separates from Detroit (Sites 1203 and 1204), Nintoku (Site 1205), and Koko (Site 1206) Seamounts (Ocean Drilling Program (ODP) Leg 197) and Meiji Seamount (Deep Sea Drilling Project (DSDP) Leg 19, Site 192). Plateaus in incremental heating age spectra for Site 1203 lava flows give a mean age of 75.8×0.6 (2σ) Ma, which is consistent with the normal magnetic polarity directions observed and biostratigraphic age assignments. Site 1204 lavas produced discordant spectra, indicating Ar loss by reheating and K mobilization. Six plateau ages from lava flows at Site 1205 give a mean age of 55.6±0.2 Ma, corresponding to Chron 24r. Drilling at Site 1206 intersected a N-R-N magnetic polarity sequence of lava flows, from which six plateau ages give a mean age of 49.1±0.2 Ma, corresponding to the Chron 21n-22r-22n sequence. Plateau ages from two feldspar separates and one lava from DSDP Site 192 range from 34 to 41 Ma, significantly younger than the Cretaceous age of overlying sediments, which we relate to postcrystallization K mobilization. Combined with new dating results from Suiko Seamount (DSDP Site 433) and volcanoes near the prominent bend in the lineament [Sharp and Clague, 2002], the overall trend is increasing volcano age from south to north along the Emperor Seamounts, consistent with the hot spot model. However, there appear to be important departures from the earlier modeled simple linear age progression, which we relate to changes in Pacific plate motion and the rate of southward motion of the Hawaiian hot spot.
Year of Publication: 2004
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 03 Geochronology; Absolute age; Ar/Ar; Basement; Biostratigraphy; Cenozoic; DSDP Site 192; Dates; Deep Sea Drilling Project; East Pacific Ocean Islands; Emperor Seamounts; Feldspar group; Framework silicates; Hawaii; Hot spots; Igneous rocks; Koko Seamount; Lava; Leg 19; Leg 197; Louisville trend; Mantle; Mantle plumes; Meiji Seamount; Motions; Nintoku Seamount; North Pacific; Northwest Pacific; ODP Site 1203; ODP Site 1205; ODP Site 1206; Ocean Drilling Program; Oceania; Pacific Ocean; Pacific Plate; Paleogene; Plate tectonics; Polynesia; Silicates; Suiko Seamount; Tertiary; United States; Volcanic rocks; Volcanoes; West Pacific; Whole rock
Record ID: 2004083702
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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