Other
Scientific paper
Oct 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997e%26psl.151..205k&link_type=abstract
Earth and Planetary Science Letters, Volume 151, Issue 3-4, p. 205-223.
Other
22
Scientific paper
Phenocryst assemblages, and mineral and melt inclusion compositions of magmas erupted at near-axis seamounts on either side of Valu Fa Ridge provide a hitherto unprecedented insight into the complexity of magma generation in this back-arc basin tectonic setting. Two fundamentally different primitive primary melt compositions are identified based on melt inclusion compositions, olivine phenocryst chemistry, and the early co-crystallisation of either magnesian clinopyroxene (Mg# to 93) or magnesian orthopyroxene (Mg# to 93.5) with magnesian olivine (to Fo94) and Cr-rich spinel (Cr# = 0.78-0.87). One magma type is a H2O-rich (~ 2.5 wt%), high-CaO (~ 14 wt%), low-Al2O3 (~ 8 wt%) magnesian basalt, variants of which occur in both the eastern and western seamounts. The other is a low-Ca boninite-like magma that only occurs as a component of the western seamount magmas. Large and systematic variations in incompatible trace-element compositions of melt inclusions trapped in primitive olivine phenocrysts, reflect an integration of diverse but geochemically related melt fractions to produce the magmas at each seamount. Trace-element systematics require the variable addition of a LILE-, Pb-, and Cl-rich component to the mantle wedge source with increased influence toward the Tofua arc. This component, as invoked in most models of arc magma genesis, is likely to be a supercritical aqueous fluid released by dehydrating subducting ocean crust beneath the volcanic arc front. We propose that southward propagation of the back-arc basin spreading center mantle provided heat necessary to generate both magmatic suites by decompression melting of refractory hydrated sub-arc lithosphere, probably veined by clinopyroxene-rich dykes in the case of the high-CaO magma series. These near-ridge seamount lavas are very similar to those drilled at ODP Site 839 in the Lau Basin, and we suggest that the Site 839 basalts, as well as other Lau Basin seamount arc-like magmas, were produced from sub-arc lithosphere during southward propagation of the Eastern Lau Spreading Center ~ 2-3 Ma.
Crawford Anthony J.
Eggins Stephen
Kamenetsky Vadim S.
Mühe Richard
No associations
LandOfFree
Phenocryst and melt inclusion chemistry of near-axis seamounts, Valu Fa Ridge, Lau Basin: insight into mantle wedge melting and the addition of subduction components does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Phenocryst and melt inclusion chemistry of near-axis seamounts, Valu Fa Ridge, Lau Basin: insight into mantle wedge melting and the addition of subduction components, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Phenocryst and melt inclusion chemistry of near-axis seamounts, Valu Fa Ridge, Lau Basin: insight into mantle wedge melting and the addition of subduction components will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1770604