E-type MORB

Anomalous ocean ridge (characterized by E-type MORB) spreading centre... 

Within-plate alkali basalts plot in field A within-plate riioleiites plot in fields All and C. E-type MORB plots in field B whilst N-type MORB plots in field D. Volcanic-arc basalts also plot in fields C and D. The several areas of overlap mean that only within-plate alkali basalts and E-type MORB can be identified without ambiguity,... 

Figure SJl The La/lO-Y/lS-Nb/8 discrimination diagram for basalts (after Cabanis and LecoUe, 1989). The plotting coordinates are shown around the margin of the diagram the broken lines are drawn normal to the sides of the triangular diagram. Field 1 contains volcanic-arc basalts, held 2 continental basalts and held 3 oceanic basalts. The subdivisions of the fields arc as follows I A, calc-alkali basalts 1C, volcanic-arc rholeiites IB is an area of overlap between lA and 1C 2A, continental basalts 2B, back-arc basin basalts (although this is less well defined) 3A, alkali basalts from intercontinental rift 3B, 3C, E-type MORB (3B enriched, 3C weakly enriched), 3D, N-type MORB,...

Table 2 Representative analyses of MORBs. Kolbeinsey Ridge, northern EPR, and mid-Cayman Rise encompass much of the global range in extents and pressures of melting. Also shown are examples of an Indian Ocean MORE and composite analyses of a normal (N-MORB), a transitional (T-type) MORE, and an enriched (E-type) MORE from the MAR. 

Rampone E., Hofmann A. W., Piccardo G. B., Vannucci R., Bottazzi P., and Ottolini L. (1996) Trace element and isotope geochemistry of depleted peridotites from an N-MORB type ophiolite (Internal Liguride N. Italy). Contrib. Mineral. Petrol. 123, 61-76. 

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