High 3He/4He ratios in the Manus backarc basin: Implications for mantle mixing and the origin of plumes in the western Pacific Ocean

Research Article| November 01, 1998 High 3He/4He ratios in the Manus backarc basin: Implications for mantle mixing and the origin of plumes in the western Pacific Ocean Colin G. Macpherson; Colin G. Macpherson 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Search for other works by this author on: GSW Google Scholar David R. Hilton; David R. Hilton 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Search for other works by this author on: GSW Google Scholar John M. Sinton; John M. Sinton 2Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii 96822 Search for other works by this author on: GSW Google Scholar Robert J. Poreda; Robert J. Poreda 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Search for other works by this author on: GSW Google Scholar Harmon Craig Harmon Craig 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Search for other works by this author on: GSW Google Scholar Author and Article Information Colin G. Macpherson 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 David R. Hilton 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 John M. Sinton 2Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii 96822 Robert J. Poreda 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Harmon Craig 1Isotope Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, University of California—San Diego, La Jolla, California 92093-0220 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (11): 1007–1010. https://doi.org/10.1130/0091-7613(1998)026<1007:HHHRIT>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Colin G. Macpherson, David R. Hilton, John M. Sinton, Robert J. Poreda, Harmon Craig; High 3He/4He ratios in the Manus backarc basin: Implications for mantle mixing and the origin of plumes in the western Pacific Ocean. Geology 1998;; 26 (11): 1007–1010. doi: https://doi.org/10.1130/0091-7613(1998)026<1007:HHHRIT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Helium isotope ratios in oceanic glasses provide a high-integrity tracer of contributions from mantle plumes. Despite a diverse array of petrogenetic affinities, glasses from the central part of the Manus Basin—a backarc basin in the western Pacific—have typical plume (or hotspot) 3He/4He ratios that cluster around 12.2RA (±1.0RA n =18, where RA =3He/4He of air), a value significantly higher than the range found in most mid-ocean-ridge basalts (MORB) ([8 ± 1]A). Lavas in other parts of the basin have MORB-like or lower 3He/4He values. A wide range of He concentrations characterizes the Manus Basin glasses: This is considered to reflect the high water content of some lavas, which promotes He loss through volatile degassing. For the most part, it is the degassed lavas that do not show the plume He isotope signature. Results of the present study, together with 3He/4He data for lavas and gases from islands to the south and east of the Bismark Sea, indicate that the focus of mantle plume upwelling is either the center of the Manus Basin or possibly the region to the northwest beneath the volcanic islands of the St. Andrew Strait. This region of plume or hotspot 3He/4He ratios coincides with a domain of anomalously low seismic velocities at the underlying core-mantle boundary, and indicates that the provenance of high-3He/4He magmas in the Manus Basin (and possibly elsewhere) is linked to this boundary layer—either by plume entrainment of lower mantle or, more speculatively, through addition of material from the core-mantle boundary. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.