Zierenberg, "The laboratory albitization of mid-ocean ridge basalt," Journal of Geology, vol.
Black diamond represents the composition of seawater at 2[degrees]C and red diamond represents the isochemical dissolution of mid-ocean ridge basalt. The dashed red curve shows the evolution of the fluid composition from fluid-buffered to rock-buffered conditions at a temperature of 400[degrees]C.
Instead of pointing at the composition corresponding to dissolved mid-ocean ridge basalts, the rock-buffered fluid end-member compositions are characterized by Mg-Na depletions and Ca-K enrichment characteristic of the overall fluid/rock interaction process predicted by the model (Figure 6).
Michael, P.J., and Chase, R.L., 1987, The influence of primary magma composition, [H.sub.2]O , and pressure on mid-ocean ridge basalt differentiation: Contributions to Mineralogy and Petrology, v.
Leybourne, M.I., and Van Wagoner, N.A., 1991, Heck and Heckle Seamounts, northeast Pacific Ocean: High extrusion rates of primitive and highly depleted mid-ocean ridge basalts on off-ridge seamounts: Journal of Geophysical Research, v.
and Hoover, J.D., 1984, Composition and depth of origin of primary mid-ocean ridge basalts: Contributions to Mineralogy and Petrology, v.
Today, based mostly on isotopic data from OIB and mid-ocean ridge basalt
(MORB), five types of mantle-source regions, or components, are recognized (Zindler and Hart, 1986; Hofmann, 2003).
The rest of the whole-rock geochemical signature points to a within-plate setting with character transitional between enriched mid-ocean ridge basalts
(EMORB) and ocean-island basalts (OIB) and no prominent crustal contamination (Fig.
They reported mid-ocean ridge basalts
, island arc tholeiites, within-plate tholeiites and alkali basalts.
This new composite magma chamber model has broad implications for the composition of mid-ocean ridge basalts
and how they vary along the ridge crest, the structure and formation of the lower oceanic crust, the circulation of hydrothermal fluids, and the longevity of mid-ocean ridge hydrothermal systems.