Geothermobarometry of basaltic glasses from the Tamu Massif, Shatsky Rise oceanic plateau

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doi: 10.1002/ggge.20231
Author(s): Husen, Anika; Almeev, Renat R.; Holtz, François; Koepke, Jürgen; Sano, Takashi; Mengel, Kurt
Author Affiliation(s): Primary:
Leibniz University of Hannover, Institute of Mineralogy, Hannover, Germany
Other:
National Museum of Nature and Science, Japan
Clausthal University of Technology, Germany
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 14(10), p.3908-3928. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 53 refs.; illus., incl. 2 tables
Summary: We present the results of a petrological study of core samples from Tamu Massif (Site U1347), recovered during the Shatsky Rise Integrated Ocean Drilling Program (IODP) Expedition 324. The basaltic glasses from Site U1347 are evolved tholeiitic basalts containing 5.2-6.8 wt% MgO, and are principally located within the compositional field of mid-ocean ridge basalts (MORBs) but they have systematically higher FeO, lower Al2O3, SiO2, and Na2O concentrations, and the CaO/Al2O3 ratios are among the highest known for MORBs. In this sense, glasses from Site U1347 more closely resemble basaltic magmas from the Ontong Java Plateau (OJP), although they still have lower SiO2 concentrations. In contrast to MORB and similar to OJP, our fractionation corrected values of Na2O and CaO/Al2O3 indicate more than 20% of partial melting of the mantle during the generation of the parental magmas of Tamu Massif. The water contents in the glasses, determined by midinfrared Fourier transform infrared (FTIR) spectroscopy, are MORB-like, and vary between 0.18 and 0.6 wt% H2O. The calculated pressure (P)-temperature (T) conditions at which the natural glasses represent cotectic olivine-plagioclase-clinopyroxene compositions range from 0.1 to 240 MPa and 1100 to 1150°C reflecting magma storage at shallow depth. The variation of the glass compositions and the modeled P-T conditions in correlation with the relative ages indicate that there were at least two different magmatic cycles characterized by variations in eruptive styles (massive flows or pillow lavas), chemical compositions, volatile contents, and preeruptive P-T conditions. Each magmatic cycle represents the progressive differentiation in course of polybaric crystallization after the injection of a more primitive magma batch. Magma crystallization and eruption episodes are followed by magmatic inactivity reflected in the core sequence by a sedimentary layer. Our data for Tamu Massif demonstrate that, similar to Ontong Java ocean Plateau, the crystallization beneath Shatsky Rise occurs at different crustal levels. Abstract Copyright (2013), American Geophysical Union. All Rights Reserved.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 05 Petrology, Igneous and Metamorphic; Basaltic composition; Basalts; COMAGMAT; Chain silicates; Clinopyroxene; Computer programs; Crust; Data processing; Eruptions; Expedition 324; Feldspar group; Framework silicates; Geologic barometry; Geologic thermometry; Glasses; IODP Site U1346; IODP Site U1347; IODP Site U1348; IODP Site U1349; IODP Site U1350; Igneous rocks; Integrated Ocean Drilling Program; Leg 198; Magma chambers; Magmas; Magmatic differentiation; Mid-ocean ridge basalts; Mineral assemblages; Nesosilicates; North Pacific; Northwest Pacific; Numerical models; ODP Site 1213; Ocean Drilling Program; Ocean floors; Oceanic crust; Olivine; Olivine group; Ontong Java Plateau; Ori Massif; Orthosilicates; Pacific Ocean; Plagioclase; Pyroxene group; Shatsky Rise; Shirshov Massif; Silicates; Tamu Massif; Thermodynamic properties; Volcanic rocks; Volcanism; West Pacific
Coordinates: N300000 N400000 E1660000 E1540000
Record ID: 2014071016
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union