30. Chemical Diversity of Abyssal Volcanic Glass Erupted Along Pacific, Atlantic, and Indian Ocean Sea-Floor Spreading Centers

  1. George H. Sutton,
  2. Murli H. Manghnani,
  3. Ralph Moberly and
  4. Ethel U. Mcafee
  1. W. G. Melson1,
  2. T. L. Vallier2,
  3. T. L. Wright3,
  4. G. Byerly4 and
  5. J. Nelen4

Published Online: 17 MAR 2013

DOI: 10.1029/GM019p0351

The Geophysics of the Pacific Ocean Basin and Its Margin

The Geophysics of the Pacific Ocean Basin and Its Margin

How to Cite

Melson, W. G., Vallier, T. L., Wright, T. L., Byerly, G. and Nelen, J. (1976) Chemical Diversity of Abyssal Volcanic Glass Erupted Along Pacific, Atlantic, and Indian Ocean Sea-Floor Spreading Centers, in The Geophysics of the Pacific Ocean Basin and Its Margin (eds G. H. Sutton, M. H. Manghnani, R. Moberly and E. U. Mcafee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM019p0351

Author Information

  1. 1

    Smithsonian Institution, Washington, D.C. 20560

  2. 2

    Scripps Institution of Oceanography, La Jolla, California 92037

  3. 3

    U.S. Geological Survey, Washington, D.C. 20402

  4. 4

    Smithsonian Institution, Washington, D.C. 20560

Publication History

  1. Published Online: 17 MAR 2013
  2. Published Print: 1 JAN 1976

ISBN Information

Print ISBN: 9780875900193

Online ISBN: 9781118663592

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Keywords:

  • Geophysics—Pacific area—Congress;
  • Woollard, George Prior, 1908

Summary

The abundant glassy rinds and chilled contacts of submarine extrusions and intrusions provide the most reliable indicators of primary magmatic compositions of deep-sea igneous rocks. They are homogeneous at the precision of electron microprobe analyses, so that even small sub-samples are reliable indicators of the composition of larger eruptive units. Analyses of such sea-floor glasses by electron microprobe techniques for Si. Al. Fe. Mg. Ca, Na. K. Ti, and P reveal an extremely diverse compositional spread, ranging from highly differentiated basalt to varieties extremely depleted in large ion lithophile clemcnts. A preliminary look at glasses from active spreading centers suggests that the FETI basalt group (high FeO and TiO2. low MgO) is more common at rapidly spreading ridges (East Pacific rise system) than at slower spreading ridges (Mid-Atlantic ridge system). The data presented here appear for the most part inadequate for meaningful assessment of chemical gradients along spreading centers. There is strong evidence, though, that some segments of spreading centers have erupted similar lava compositions over tens of millions of years. These similar chemical groups are symmetrically distributed on each side of spreading segments as is expected from sea-floor spreading models. There is very little overlap in the compositions of the basaltic chemical groups at the level of precision of the electron probe analyses. However, there are a few Atlantic chemical groups that occur both in the North and South Atlantic. Even these intra-ocean matches of chemical groups from one locality to another are, however. remarkably few. This survey shows the great predominance of various basalt types at spreading centers, but other rock types. including soda rhyolite from the Galapagos rise, occur rarely.