The longevity of the South Pacific isotopic and thermal anomaly

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doi: 10.1016/0012-821X(91)90015-A
Authors:Staudigel, Hubert; Park, Kye Hun; Pringle, Malcolm S.; Rubenstone, J. L.; Smith, W. H. F.; Zindler, Alan
Author Affiliations:Primary:
Scripps Inst. Oceanogr., La Jolla, CA, United States
Other:
Lamont-Doherty Geol. Obs., United States
U. S. Geol. Surv., United States
Korea Sci. Cent., South Korea
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 102(1), p.24-44. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:1991
Note:In English. 53 refs.; illus. incl. 3 tables, sketch maps
Summary:The South Pacific is anomalous in terms of the Sr, Nd and Pb isotope ratios of its hot spot basalts, a thermally enhanced lithosphere, and possibly a hotter mantle. We have studied the Sr, Nd and Pb isotope characteristics of 12 Cretaceous seamounts in the Magellans, Marshall and Wake seamount groups (western Pacific Ocean) that originated in this South Pacific Isotopic and Thermal Anomaly (SOPITA). The range and values of isotope ratios of the Cretaceous seamount data are similar to those of the island chains of Samoa, tahiti, Marquesas and Cook/Austral in the SOPITA. These define tow major mantle components suggesting that isotopically extreme lavas have been produced at SOPITA for at least 120 Ma. Shallow bathymetry and weakened lithosphere beneath some of the seamounts studied suggests that at least some of the thermal effects prevailed during the Cretaceous as well. These data, in the context of published data, suggest: (1) SOPITA is a long-lived feature, and enhanced heat transfer into the lithosphere and isotopically anomalous mantle appear to be an intrinsic characteristic of the anomaly. (2) The less pronounced depth anomaly during northwesterly plate motion suggests that some of the expressions of SOPITA may be controlled by the direction of plate motion. Motion parallel to the alignment of SOPITA hot spots focuses the heat (and chemical input into the lithosphere) on a smaller cross section than oblique motion. (3) The lithosphere in the eastern nd central SOPITA appears to have lost its original depleted mantle characteristics, probably due to enhanced plume/lithosphere interaction, and it is dominated by isotopic compositions derived from plume materials. (4) We speculate that the origin of the SOPITA, and possibly the DUPAL anomaly is largely due to focussed subduction through long periods of the geological history of the earth, creating a heterogeneous distribution of recycled components in the lower mantle.
Subjects:Alkaline earth metals; Anomalies; Basalts; Cretaceous; Crust; Geochemistry; Heat flow; Hot spots; Igneous rocks; Isotopes; Lead; Mesozoic; Metals; Movement; Nd-144/Nd-143; Neodymium; Oceanic crust; Plate tectonics; Rare earths; Seamounts; Sr-87/Sr-86; Stable isotopes; Strontium; Tectonophysics; Thermal regime; Volcanic rocks; Marshall Islands; Micronesia; North Pacific; Oceania; Pacific Ocean; South Pacific; Wake; West Pacific Ocean Islands; Magellan Seamounts; Ocean island basalts; Ratios; SOPITA; South Pacific isotopic and thermal anomaly
Coordinates:N050000 N250000 E1750000 E1450000
Abstract Numbers:91M/3120
Record ID:1991021917
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand
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