Frozen magma lenses below the oceanic crust

Publication Type  Journal Article
Year of Publication  2005
Authors  Nedimovic, M. R.; Carbotte, S. M.; Harding, A. J.; Detrick, R. S.; Canales, J. P.; Diebold, J. B.; Kent, G. M.; Tischer, M.; Babcock, J. M.
Journal Title  Nature
Volume  436
Issue  7054
Pages  1149-1152
Journal Date  Aug 25
ISBN Number  0028-0836
Accession Number  ISI:000231416600044
Key Words  moho transition zone; east pacific rise; oman ophiolite; mantle transition; islands ophiolite; spreading center; beneath; chambers; ridges; origin

The Earth's oceanic crust crystallizes from magmatic systems generated at mid-ocean ridges. Whereas a single magma body residing within the mid-crust is thought to be responsible for the generation of the upper oceanic crust, it remains unclear if the lower crust is formed from the same magma body, or if it mainly crystallizes from magma lenses located at the base of the crust(1-3). Thermal modelling(4-6), tomography(7), compliance(8) and wide-angle seismic studies(9), supported by geological evidence(3,10-18), suggest the presence of gabbroic-melt accumulations within the Moho transition zone in the vicinity of fast- to intermediate-spreading centres. Until now, however, no reflection images have been obtained of such a structure within the Moho transition zone. Here we show images of groups of Moho transition zone reflection events that resulted from the analysis of similar to 1,500 km of multichannel seismic data collected across the intermediate-spreading-rate(19) Juan de Fuca ridge. From our observations we suggest that gabbro lenses and melt accumulations embedded within dunite or residual mantle peridotite are the most probable cause for the observed reflectivity, thus providing support for the hypothesis that the crust is generated from multiple magma bodies.


958AKTimes Cited:8Cited References Count:25

URL  <Go to ISI>://000231416600044
DOI  Doi 10.1038/Nature03944