Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic)

Tartarotti, Paola; Susini, Sara; Nimis, Paolo; Ottolini, Luisa

doi:10.1016/s0024-4937(02)00116-0

Cited by 87 publications

(56 citation statements)

References 46 publications

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“…Melt impregnation and refertilization of the lithospheric mantle is caused by the interstitial crystallization of percolating melts. This process leads to the formation of plagioclase-(±px) rich peridotites, and it has been widely documented in abyssal (Hebert et al 1983;Dick 1989;Cannat et al 1990;Hekinian et al 1993;Constantin et al 1995;Seyler et al 2001;Tartarotti et al 2002;Chazot et al 2005;von der Handt et al 2006) and ophiolitic peridotites (e.g. Menzies 1973;Menzies and Allen 1974;Dick 1977;Jackson and Ohnenstetter 1981;Boudier and Nicolas 1977;Nicolas 1986Nicolas , 1989Tartarotti and Vaggelli 1995;Rampone et al 1997;Dijkstra et al 2001;Piccardo 2003;Piccardo et al 2004Müntener et al 2004;Piccardo and Vissers 2007;).…”

Section: Introductionmentioning

confidence: 97%

Multi-stage melt–rock interaction in the Mt. Maggiore (Corsica, France) ophiolitic peridotites: microstructural and geochemical evidence

Rampone

Piccardo

Hofmann

2008

Contrib Mineral Petrol

114

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Spinel and plagioclase peridotites from the Mt.Maggiore (Corsica, France) ophiolitic massif record a composite asthenosphere-lithosphere history of partial melting and subsequent multi-stage melt-rock interaction. Cpx-poor spinel lherzolites are consistent with mantle residues after low-degree fractional melting (F = 5-10%). Opx + spinel symplectites at the rims of orthopyroxene porphyroclasts indicate post-melting lithospheric cooling (T = 970-1,100°C); this was followed by formation of olivine embayments within pyroxene porphyroclasts by melt-rock interaction. Enrichment in modal olivine (up to 85 wt%) at constant bulk Mg values, and variable absolute REE contents (at constant LREE/HREE) indicate olivine precipitation and pyroxene dissolution during reactive porous melt flow. This stage occurred at spinel-facies depths, after incorporation of the peridotites in the thermal lithosphere. Plagioclase-enriched peridotites show melt impregnation microtextures, like opx + plag intergrowths replacing exsolved cpx porphyroclasts and interstitial gabbronoritic veinlets. This second melt-rock interaction stage caused systematic chemical changes in clinopyroxene (e.g. Ti, REE, Zr, Y increase), related to the concomitant effects of local melt-rock interaction at decreasing melt mass, and crystallization of small (\3%) trapped melt fractions. LREE depletion in minerals of the gabbronoritic veinlets indicates that the impregnating melts were more depleted than normal MORB. Preserved microtextural evidence of previous melt-rock interaction in the impregnated peridotites suggests that they were progressively uplifted in response to lithosphere extension and thinning. Migrating melts were likely produced by mantle upwelling and melting related to extension; they were modified from olivine-saturated to opx-saturated compositions, and caused different styles of melt-rock interaction (reactive spinel harzburgites, vs. impregnated plagioclase peridotites) depending on the lithospheric depths at which interaction occurred.

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Section: Introductionmentioning

confidence: 97%

Multi-stage melt–rock interaction in the Mt. Maggiore (Corsica, France) ophiolitic peridotites: microstructural and geochemical evidence

Rampone

Piccardo

Hofmann

2008

Contrib Mineral Petrol

114

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“…A high modal abundance of plagioclase and pyroxene coupled to a low modal value of olivine (Table 1) is a characteristic feature of melt -impregnated plagioclase peridotites (e.g., Dick, 1989;Tartarotti et al, 2002). In addition, textural characteristics of the Nain lherzolite also strongly indicate that the plagioclase and associated minerals (mainly clinopyroxene) were precipitated from impregnating melt (Fig.…”

Section: Resultsmentioning

confidence: 96%

Post-deformational impregnation of depleted MORB in Nain lherzolite (Central Iran)

Pirnia

Arai

Torabi

2010

Journal of Mineralogical and Petrological Sciences

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Plagioclase lherzolites of Nain mélange, Iran, show peculiar textures that indicate melt impregnation: (1) droplet or bleb -like grains of plagioclase distributed in the peridotite matrix, (2) plagioclase -bearing clinopyroxenite seams, and (3) trails of plagioclase crosscutting pyroxene porphyroclasts. The textural characteristics show post -deformational igneous formation of plagioclase, and possibly, associated clinopyroxene, from the impregnating melt. The melt has precipitated the clinopyroxenite seams and chemically modified all the peridotite minerals. Highly refractory compositions of the precipitated minerals suggest involvement of a highly depleted MORB -like melt. The melt was an increment of partial melt produced by 8% to 10% fractional melting from the MORB source. This is in contrast to the involvement of ordinary MORB in melt impregnation in abyssal plagioclase peridotites. Integration of increments of mantle partial melts to form MORB was possibly incomplete in the very incipient mid -ocean ridge as in the short -lived Nain back -arc basin.

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“…Johnson et al, 1990). Although bulk trace element compositions of these peridotites are heavily modified by alteration on the seafloor, many workers have analyzed the trace element composit~ons (Sr, Zr, Ti, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb, and Y) of relict, unaltered clinopyroxene grains as a means of chemical characterization (Johnson et al, 1990;Johnson and Dick, 1992;Dick and Natland, 1996;Hellebrand et al, 2002;Salters and Dick, 2002;Tartarotti et al, 2002). Using such clinopyroxene compositions, bulk compositions (C,,,,,,,,) of the peridotites can be cdculated for each trace element with the following equation:…”

Section: Abyssal Peridatiresmentioning

confidence: 99%

“…We have compiled a data set from the literature that includes abyssal peridotites having both cpx trace element analyses and modal abundances (data sources are Johnson et at., 1990;Johnson and Dick, 1992;Dick et al, 1984;Dick and Natland, 1996;Hellebrand et al, 2002;Salters and Dick, 2002;Tartarotti et al, 2002). All samples containing more than 1 % modal plagioclase are excluded on the basis that most plagioclase in abyssal peridotites has been interpreted as a secondary phase representative of melt impregnation (Dick, 1989;Tartarotti et al, 2002); as a result, only 5 out of almost 90 samples included have any reported modal plagioclase at all.…”

Section: Abyssal Peridatiresmentioning

confidence: 99%

Geochemical characterization of endmember mantle components

Workman¹

2005

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Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic)

Cited by 87 publications

References 46 publications

Multi-stage melt–rock interaction in the Mt. Maggiore (Corsica, France) ophiolitic peridotites: microstructural and geochemical evidence

Multi-stage melt–rock interaction in the Mt. Maggiore (Corsica, France) ophiolitic peridotites: microstructural and geochemical evidence

Post-deformational impregnation of depleted MORB in Nain lherzolite (Central Iran)

Geochemical characterization of endmember mantle components

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