Role of melting process and melt–rock reaction in the formation of Jurassic MORB-type basalts (Alpine ophiolites)

Renna, Maria Rosaria; Tribuzio, R.; Sanfilippo, Alessio; Thirlwall, M. F.

doi:10.1007/s00410-018-1456-3

Cited by 16 publications

(9 citation statements)

References 94 publications

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“…The initial melt composition adopted is a primitive MORB-type basalt (Mg# ¼ 70Á75 mol %) associated with the Pineto gabbroic suite (Saccani et al, 2008; Alpine ophiolite), the composition of which is given in Table 7. This primitive melt is characterized by a relatively low Ca/Na ratio (Ca# ¼ 61Á54 mol %), most probably as the result of low degrees of mantle melting (Klein & Langmuir, 1987;Montanini et al, 2008;Saccani et al, 2008;Renna et al, 2018), similar to what was described at the easternmost South-West Indian Ridge (Ca# ¼ 55-60 mol %; Paquet et al, 2016). Such an Na-rich parental melt composition is consistent with the Alpine-Apennine compositional field of gabbroic rocks ( Fig.…”

Section: Thermodynamic Model Of Olivine-consuming Reactive Crystallizsupporting

confidence: 78%

“…Marroni et al, 1998;Tribuzio et al, 2000Tribuzio et al, , 2004Montanini et al, 2008;Saccani et al, 2008), and the Na-rich composition of the basaltic parental melts ( Fig. 14c; Saccani et al, 2008;see Discussion) are consistent with low-degree melting of the upwelling mantle in a slow-to ultraslow-spreading environment (Klein & Langmuir, 1987;Montanini et al, 2008;Saccani et al, 2008;Renna et al, 2018;Fig. 19a).…”

Section: Constraints On the Geodynamic Context And Melt-rock Interactmentioning

confidence: 66%

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Multi-stage Reactive Formation of Troctolites in Slow-spreading Oceanic Lithosphere (Erro–Tobbio, Italy): a Combined Field and Petrochemical Study

Basch

Rampone

Crispini

et al. 2019

Journal of Petrology

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Many recent studies have investigated the replacive formation of troctolites from mantle protoliths and the compositional evolution of the percolating melt during melt–rock interaction processes. However, strong structural and geochemical constraints for a replacive origin have not yet been established. The Erro–Tobbio impregnated mantle peridotites are primarily associated with a hectometre-size troctolitic body and crosscutting gabbroic dykes, providing a good field control on melt–rock interaction processes and subsequent magmatic intrusions. The troctolitic body exhibits high inner complexity, with a host troctolite (Troctolite A) crosscut by a second generation of troctolitic metre-size pseudo-tabular bodies (Troctolite B). The host Troctolite A is characterized by two different textural types of olivine, corroded deformed millimetre- to centimetre-size olivine and fine-grained rounded undeformed olivine, both embedded in interstitial to poikilitic plagioclase and clinopyroxene. Troctolite A shows melt–rock reaction microstructures indicative of replacive formation after percolation and impregnation of mantle dunites by a reactive melt. The evolution of the texture and crystallographic preferred orientation (CPO) of olivine are correlated and depend on the melt/rock ratio involved in the impregnation process. A low melt/rock ratio allows the preservation of the protolith structure, whereas a high melt/rock ratio leads to the disaggregation of the pre-existing matrix. The mineral compositions in Troctolite A define reactive trends, indicative of the buffering of the melt composition by assimilation of olivine during impregnation. The magmatic Troctolite B bodies are intruded within the pre-existing Troctolite A and are characterized by extreme textural variations of olivine, from decimetre-size dendritic to fine-grained euhedral crystals embedded in poikilitic plagioclase. This textural variability is the result of olivine assimilation during melt–rock reaction and the correlated increase in the degree of undercooling of the percolating melt. In the late gabbroic intrusions, mineral compositions are consistent with the fractional crystallization of melts modified after the reactive crystallization of Troctolites A and B. The Erro–Tobbio troctolitic body has a multi-stage origin, marked by the transition from reactive to fractional crystallization and diffuse to focused melt percolation and intrusion, related to progressive exhumation. During the formation of the troctolitic body, the melt composition was modified and controlled by assimilation and concomitant crystallization reactions occurring at low melt supply. Similar processes have been described in ultraslow-spreading oceanic settings characterized by scarce magmatic activity.

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Section: Thermodynamic Model Of Olivine-consuming Reactive Crystallizsupporting

confidence: 78%

Section: Constraints On the Geodynamic Context And Melt-rock Interactmentioning

confidence: 66%

Multi-stage Reactive Formation of Troctolites in Slow-spreading Oceanic Lithosphere (Erro–Tobbio, Italy): a Combined Field and Petrochemical Study

Basch

Rampone

Crispini

et al. 2019

Journal of Petrology

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“…Aside from type-1 basalts, a few percent of extrusive basalts can be ascribed as enriched-basalts (E-MORB, types-2 and 3). Additional occurrences of E-MORBs have been reported previously in other fossil OCT in the Alps (External Ligurides and Corsica; Montanini et al, 2008;Renna et al, 2018;Saccani et al, 2008). The enriched nature of these basalts was attributed to the simultaneous melting of the Jurassic ascending asthenosphere (i.e.…”

Section: The Formation Of "E-morb"-like Basalts (Types-2 and 3)supporting

confidence: 68%

“…In contrast, Alpine-Apennine ophiolites expose remnants of the OCTs of the ancient magma-poor Jurassic Alpine Tethys, which provide information not only on the basalts but also on the underlying mantle (Picazo et al, 2016). Previous studies on basalts derived from the fossil Alpine-Tethys OCT show that they are characterized by a wide range of trace element compositions, from depleted basalts (Bill et al, 2000;Desmurs et al, 2002;Durand-Delga et al, 1997;Kramer et al, 2003;Montanini et al, 2008;Piccardo, 2008;Saccani et al, 2008) to enriched basalts (Frisch et al, 1994;Renna et al, 2018;Steinmann and Stille, 1999;Vannucci et al, 1993) leading to various interpretations concerning the parental sources of these basalts. Over the last decade, a considerable data set has been acquired on the mantle rocks from Alpine-Tethys OCTs (Müntener et al, 2010;Picazo et al, 2016;Piccardo, 2016;Rampone et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Geochemical characteristics of basalts related to incipient oceanization: The example from the Alpine‐Tethys OCTs

et al. 2019

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Basalts exposed in the Platta and Tasna nappes (SE Switzerland) derive from the Alpine-Tethys Ocean-Continent Transitions (OCT) and overlie SubContinental Lithospheric Mantle (SCLM). We show that the trace element signatures of these basalts differ from Mid-Ocean Ridge Basalts (MORB). Two types of basalts occur in the OCT: a type-1 showing a "garnet signature" that can be modeled by the partial melting of the SCLM in the spinel stability field and a type-2 characterized by an enrichment in incompatible elements that can be explained by the mixing between garnet-pyroxenite-derived melts and the melting of either a depleted MORB mantle or a refertilized SCLM. Based on geological and geochemical observations we propose that the basalts from the Alpine-Tethys OCTs result from a poly-phase magmatic system that carry an inherited SCLM signature.These basalts should therefore be referred to as OCT-basalts rather than as MOR-basalts.

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“…The equilibration between minerals and migrating melts leads to changes in mineral and melt chemistry at the reaction front, and these reactive melts crystallize new phases around partly resorbed pre-existing minerals, ultimately modifying or even completely replacing the original crystal matrix (Coogan et al, 2000;Lissenberg and Dick, 2008;Suhr et al, 2008;Drouin et al, 2009;Drouin et al, 2010;Sanfilippo et al, 2015;Tamura et al, 2016Ferrando et al, 2018. Whether leading to partial melting of the host rocks or selective dissolution of a crystal matrix, the assimilation of crustal material in the ascending magmas may be sufficiently efficient (Kvassnes and Grove, 2008;Yang et al, 2019) to potentially control the majorand trace element budgets of the melts erupted at the surface (e.g., Lissenberg and Dick, 2008;Lissenberg and MacLeod, 2016;Sanfilippo et al, 2016;Jackson et al, 2018;Renna et al, 2018;Lissenberg et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Early-Stage Melt-Rock Reaction in a Cooling Crystal Mush Beneath a Slow-Spreading Mid-Ocean Ridge (IODP Hole U1473A, Atlantis Bank, Southwest Indian Ridge)

et al. 2020

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Role of melting process and melt–rock reaction in the formation of Jurassic MORB-type basalts (Alpine ophiolites)

Cited by 16 publications

References 94 publications

Multi-stage Reactive Formation of Troctolites in Slow-spreading Oceanic Lithosphere (Erro–Tobbio, Italy): a Combined Field and Petrochemical Study

Multi-stage Reactive Formation of Troctolites in Slow-spreading Oceanic Lithosphere (Erro–Tobbio, Italy): a Combined Field and Petrochemical Study

Geochemical characteristics of basalts related to incipient oceanization: The example from the Alpine‐Tethys OCTs

Early-Stage Melt-Rock Reaction in a Cooling Crystal Mush Beneath a Slow-Spreading Mid-Ocean Ridge (IODP Hole U1473A, Atlantis Bank, Southwest Indian Ridge)

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