On the origin of some mica-lamprophyres: experimental evidence from a mafic minette

Esperança, Sonia; Holloway, John

doi:10.1007/bf00381270

Cited by 129 publications

(74 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Currently, the primary evidence of alkalibasalt fractionation arises from phlogopite-bearing ultramafic xenoliths in alkali-basalts and lamprophyres, which indicate that the fractionation sequence involves the crystallization of olivine + clinopyroxene + phlogopite ± apatite (Buhlmann et al 2000;Dawson and Smith 1992;Downes et al 2004;Giannetti 1982;Giannetti and Luhr 1990;Righter and Rosas-Elguera 2001). Experimental phase-equilibria of hydrous alkali-rich magmas corroborate the limited evidence from high-K ultramafic xenoliths (Barton and Hamilton 1978;Barton and Hamilton 1979;Edgar et al 1980;Elkins-Tanton and Grove 2003;Esperança and Holloway 1987;Melzer and Foley 2000;Righter and Carmichael 1996), yet, until now, an exposed, continuous plutonic sequence documenting such a fractionation sequence has not been described.…”

supporting

confidence: 56%

“…The major and trace element compositions of the derivative melt at 10% fractionation intervals are given in Table 2 This is primarily due to the stability of biotite on the liquidus of these melts, but also to the protracted fractionation of olivine resulting from a stability field increasing with decreasing pressure (Esperança and Holloway 1987;Righter and Carmichael 1996).…”

Section: Model Resultsmentioning

confidence: 99%

“…have found olivine + clinopyroxene + phlogopite ± spinel at multiple saturation (Edgar et al 1980;Elkins-Tanton and Grove 2003;Esperança and Holloway 1987;Melzer and Foley 2000;Righter and Carmichael 1996). Only two studies obtained conditions conducive to orthopyroxene saturation and both required CO 2 to stabilize it (Edgar et al 1980;Sato 1997).…”

Section: Experimental Studies Relevant To the Dariv Fractionation Seqmentioning

confidence: 99%

“…, P, H 2 O, and K 2 O contents will drive this reaction to the right (Esperança and Holloway 1987). This reaction is responsible for the shrinkage of the stability field of olivine in K-rich melts with increasing pressure and the decrease in olivine modal abundance with the appearance of phlogopite (Barton and Hamilton 1978;Barton and Hamilton 1979;Esperança and Holloway 1987;Righter and Carmichael 1996). As we observed a significant interval of olivine fractionation in Dariv (olivine Mg# 87 to 67), this suggests that pressures…”

Section: Experimental Studies Relevant To the Dariv Fractionation Seqmentioning

confidence: 99%

See 3 more Smart Citations

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Bucholz¹

2016

View full text Add to dashboard Cite

Fractional crystallization of mantle-derived basaltic melts is a critical process in producing a compositionally stratified continental crust characterized by a silicic upper crust and a mafic lower crust. This thesis explores outstanding questions associated with fractional crystallization through detailed field, petrological, and geochemical studies of the Dariv Igneous Complex in Western Mongolia. The Dariv Igneous Complex records the crystallization of a high-K primitive arc melt at shallow crustal levels, preserving both biotite-bearing ultramafic and mafic cumulates, as well as liquid-like evolved plutonics, such as (quartz-)monzonites. Chapter 2 presents comprehensive field and petrographic descriptions of the complex and establishes the petrogenetic groundwork to understand the conditions under which it formed. Results of this study indicate that the observed lithologies formed through the fractional crystallization of a high-K hydrous basalt, typical of alkali-rich basalts found in subduction zone settings, at 0.2-0.5 GPa and elevated oxygen fugacities. Chapter 3 presents a quantitatively modeled liquid line of descent (LLD) for the complex based on whole rock geochemical analyses, which is able to explain the trends observed in the monzonitic plutonic series observed in continental arcs. The oxygen isotope trajectory of fractionally crystallizing melts is rigorously constrained through modeling and mineral analyses in Chapter 4. This study indicates that large (1 to 1.8‰) increases in δ 18 O as a melt evolves from basaltic to granitic in composition due to the fractionation of low δ 18 O minerals. As such, the majority of δ 18 O values of upper crustal silicic plutonics can be explained through fractional crystallization of primitive arc basalts alone without needing to invoke assimilation of high δ 18 O crustal material. Finally, Chapter 5 explores the timescales associated with fractional crystallization through high precision U-Pb geochronology of zircon from the Dariv Igneous Complex. Evolution from a basaltic melt to a silica-rich monzonitic melt in the Dariv Igneous Complex occurred in <300 ka. If rates of fractional crystallization are primarily a function of cooling, this study provides an end-member constraint for fractional crystallization of a basaltic melt at relatively cool, shallow crustal levels. Together, these studies advance our understanding of the compositional, isotopic, and temporal variations associated with the formation of the continental crust.

show abstract

supporting

confidence: 56%

Section: Model Resultsmentioning

confidence: 99%

Section: Experimental Studies Relevant To the Dariv Fractionation Seqmentioning

confidence: 99%

Section: Experimental Studies Relevant To the Dariv Fractionation Seqmentioning

confidence: 99%

See 2 more Smart Citations

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Bucholz¹

2016

View full text Add to dashboard Cite

show abstract

“…Using the curves proposed by this author, between 5 and 10 kb, and compositions of alkali feldspar and plagioclase rims in contact with each other, nearsolidus temperatures were determined for these lamprophyres as close to 600°C. The liquidus temperature of Gameleira lamprophyre magma can be estimated using the experimental determinations of Esperança and Holloway (1987) for minette lamprophyres. These authors found olivine-free near-liquidus paragenesis, dominated by diopside and phlogopite, as now reported in the Gameleira lamprophyres, in systems with temperatures around 1070°C and pressures of 10 kb.…”

Section: Mineralogymentioning

confidence: 99%

Petrology of Gameleira potassic lamprophyres, São Francisco Craton

Cid

Campos

Nardi

et al. 2012

An. Acad. Bras. Ciênc.

View full text Add to dashboard Cite

Gameleira lamprophyres are dykes and mafic microgranular enclaves associated with the shoshonitic Gameleira monzonite. This association belongs to the Paleoproterozoic alkaline magmatism from Serrinha nucleus, northeast Brazil. The liquidus paragenesis is diopside, pargasite, apatite and mica. Reverse zoning was identified in the groundmass alkali feldspar and was related to the undercooling of lamprophyric magma during the emplacement, with high growth rate of pargasite/edenite inducing disequilibrium between feldspars and liquid. Chemical data indicate that the lamprophyres are basic rocks (SiO 2 < 48 wt%), with alkaline character (Na 2 O + K 2 O > 3 wt%) and potassic signature (K 2 O/Na 2 O ≈ 2). High contents of MgO and Cr are consistent with a signature of a primary liquid, and such concentrations, as well as Al, K, P, Ba, Ni-and light rare earth elements, are consistent with an olivine-free metasomatic mantle source enriched in amphibole, clinopyroxene and apatite. By contrast, the ultrapotassic lamprophyres from Morro do Afonso, contemporaneous alkaline ultrapotassic magmatism in Serrinha nucleus, were probably produced by melting of a clinopyroxene-phlogopite-apatite enriched-source. The identification of different mineral paragenesis in the source of potassic and ultrapotassic lamprophyres from Serrinha nucleus can contribute to the understanding of the mantle heterogeneities and tectonic evolution of this region.

show abstract

High Pressure Phase Relations of a Depleted Peridotite Fluxed by CO₂‐H₂O‐Bearing Siliceous Melts and the Origin of Mid‐Lithospheric Discontinuity

Saha

Dasgupta

Tsuno

2018

Geochem Geophys Geosyst

View full text Add to dashboard Cite

We present phase equilibria experiments on a depleted peridotite (Mg# 92) fluxed with variable proportions of a slab‐derived rhyolitic melt (with 9.4 wt.% H2O, 5 wt.% CO2), envisaging an interaction that could occur during formation of continents by imbrication of slabs/accretion of subarc mantles. Experiments were performed with 5 wt.% (Bulk 2) and 10 wt.% (Bulk 1) melt at 950–1175°C and 2–4 GPa using a piston‐cylinder and a multi‐anvil apparatus, to test the hypothesis that volatile‐bearing mineral‐phases produced during craton formation can cause reduction in aggregate shear‐wave velocities (VS) at mid‐lithospheric depths beneath continents. In addition to the presence of olivine, orthopyroxene, clinopyroxene, and garnet/spinel, phlogopite (Bulk 1: 3–7.6 wt.%; Bulk 2: 2.6–5 wt.%) at 2–4 GPa, and amphibole (Bulk 1: 3–9 wt.%; Bulk 2: 2–6 wt.%) at 2–3 GPa (≤1050°C) are also present. Magnesite (Bulk 1: ∼1 wt.% and Bulk 2: ∼0.6 wt.%) is present at 2–4 GPa (<1000°C at 3 and < 1050°C at 4 GPa) and its thermal breakdown coincides with the visual appearance of trace‐melt. However, an extremely small fraction of melt is inferred at all experiments based on the knowledge of fluid‐saturated peridotite solidus and the difference between bulk H2O and total H2O stored in the hydrous phases. Calculated mineral end‐member volume‐proportions were used to calculate VS of the resulting assemblage at experimental conditions and along representative continental geotherms (surface heat flow of 40–50 mWm−2). We note that reactive crystallization of phlogopite ± amphibole by infiltration of 3–10% slab‐derived hydrous‐silicic melt can cause up to 6% reduction in VS and that the estimated reduction in VS increases with increasing melt:rock ratio. The presence of phlogopite limits amphibole‐stability, making phlogopite a more likely candidate for MLDs at >100 km depth.

show abstract

On the origin of some mica-lamprophyres: experimental evidence from a mafic minette

Cited by 129 publications

References 42 publications

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Petrology of Gameleira potassic lamprophyres, São Francisco Craton

High Pressure Phase Relations of a Depleted Peridotite Fluxed by CO₂‐H₂O‐Bearing Siliceous Melts and the Origin of Mid‐Lithospheric Discontinuity

Contact Info

Product

Resources

About

On the origin of some mica-lamprophyres: experimental evidence from a mafic minette

Cited by 129 publications

References 42 publications

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia

Petrology of Gameleira potassic lamprophyres, São Francisco Craton

High Pressure Phase Relations of a Depleted Peridotite Fluxed by CO2‐H2O‐Bearing Siliceous Melts and the Origin of Mid‐Lithospheric Discontinuity

Contact Info

Product

Resources

About

High Pressure Phase Relations of a Depleted Peridotite Fluxed by CO₂‐H₂O‐Bearing Siliceous Melts and the Origin of Mid‐Lithospheric Discontinuity