In-situ Pb isotopic analysis of sulfides in abyssal peridotites: New insights into heterogeneity and evolution of the oceanic upper mantle

Research Article| February 01, 2014 In-situ Pb isotopic analysis of sulfides in abyssal peridotites: New insights into heterogeneity and evolution of the oceanic upper mantle J. Blusztajn; J. Blusztajn * 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA *E-mails: jblusztajn@whoi.edu; warrenj@stanford.edu. Search for other works by this author on: GSW Google Scholar N. Shimizu; N. Shimizu 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA Search for other works by this author on: GSW Google Scholar J.M. Warren; J.M. Warren * 2Department of Geological and Environmental Sciences, Stanford University, 450 Panama Mall, Stanford, California 94025, USA *E-mails: jblusztajn@whoi.edu; warrenj@stanford.edu. Search for other works by this author on: GSW Google Scholar H.J.B. Dick H.J.B. Dick 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA Search for other works by this author on: GSW Google Scholar Author and Article Information J. Blusztajn * 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA N. Shimizu 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA J.M. Warren * 2Department of Geological and Environmental Sciences, Stanford University, 450 Panama Mall, Stanford, California 94025, USA H.J.B. Dick 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA *E-mails: jblusztajn@whoi.edu; warrenj@stanford.edu. Publisher: Geological Society of America Received: 23 Jul 2013 Revision Received: 29 Oct 2013 Accepted: 04 Nov 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2014 Geological Society of America Geology (2014) 42 (2): 159–162. https://doi.org/10.1130/G34966.1 Article history Received: 23 Jul 2013 Revision Received: 29 Oct 2013 Accepted: 04 Nov 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation J. Blusztajn, N. Shimizu, J.M. Warren, H.J.B. Dick; In-situ Pb isotopic analysis of sulfides in abyssal peridotites: New insights into heterogeneity and evolution of the oceanic upper mantle. Geology 2014;; 42 (2): 159–162. doi: https://doi.org/10.1130/G34966.1 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 Abyssal peridotites and mid-oceanic ridge basalts (MORBs) represent complementary residue-liquid products of melting and melt migration in the oceanic mantle. Because MORBs are mixtures of melts from different mantle depths, their isotopic signature does not directly describe the isotopic composition of the mantle source, but instead describes the local average composition of different parts of the mantle. In contrast, abyssal peridotites, the residues of fractional melting and melt-rock reaction, should shed more light on the distribution of isotopic heterogeneities. We analyzed Pb isotopic compositions in sulfide grains from the Southwest Indian Ridge and the Gakkel Ridge (Arctic Ocean) using the high-resolution Cameca 1280 ion microprobe. Sulfide Pb isotope ratios show very large variations, with 16 grains from 1 sample covering ∼25% of the entire range observed in the oceanic mantle. Pb isotopes in sulfides preserve a record of mantle compositions not seen in whole-rock MORBs from the same area. Sulfides from the Atlantis II Fracture Zone (Southwest Indian Ridge) confirm the presence of ancient refractory material scatter in the oceanic upper mantle. Gakkel Ridge sulfides define a high degree of isotopic variability, suggesting that oceanic mantle, not subcontinental lithospheric mantle, is the main source of such heterogeneity. Our results confirm that the source of MORBs, as represented by abyssal peridotites, is very heterogeneous and that other mantle end-member components are intimately mixed in. In-situ sulfide analysis is a powerful tool to detect the isotopic diversity of the MORB mantle source. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.