Petrology and mineralogy of the La Peña igneous complex, Mendoza, Argentina: An alkaline occurrence in the Miocene magmatism of the Southern Central Andes

Pagano, Diego Sebastián; Galliski, Miguel Ángel; Márquez-Zavalía, María Florencia; Colombo, Fernando

doi:10.1016/j.jsames.2016.02.006

Cited by 12 publications

(3 citation statements)

References 54 publications

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“…(3) a central syenite intrusive with facies of feldspathoid syenite and monzosyenite producing an intrusive breccia at the contact between clinopyroxenite and syenite; (4) syenitic and trachytic porphyries; (5) a swarm of radial and ring dikes of several compositions including feldspathoid-bearing alkali feldspar trachytes, trachytes, and, less frequently, syenite, ledmorites, phonolites, alkaline lamprophyric rocks, intruded by thin tephritic dikes; and (6) scarce isolated bodies of late mafic breccias (Pagano et al 2016).…”

Section: Geological Setting and Petrographymentioning

confidence: 99%

“…The malignite rocks are particularly poor in MgO (2.77 to 3.32 wt.%; Mg# 30-36). On the basis of SiO 2 contents, three groups with ~37, ~45, and ~55 wt.% can be recognized in the LPC rocks, corresponding to: (1) cumulate clinopyroxenite; (2) malignite and tephrite dikes; and (3) syenite, feldspathoid syenite, trachyte, and phonolite (Pagano et al 2016), respectively. Harker diagrams of the LPC rocks show an evolution from group 1 to group 3, and within group 2 from the tephrite to malignite (Fig.…”

Section: Geochemistrymentioning

confidence: 99%

“…Zappettini et al (2015) suggested that a relatively primitive microledmorite (malignite facies) is a suitable candidate for the parental magma of the LPC rocks. Recently,Pagano et al (2016) considered that the parental magma of the LPC had a composition…”

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confidence: 99%

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Petrography, Mineralogy, and Origin of the Syenite Pegmatitic Segregation Veins From La Peña Alkaline Complex, Mendoza, Argentina

et al. 2016

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The syenite pegmatitic segregation veins (SPSV) of the Early Miocene La Peña alkaline complex (LPC), Mendoza, Argentina, are emplaced in a malignite body. They occur as veins, parallel layers, and small elliptical bodies 1 to 6 cm wide and 0.2 to 1 m in length. The veins with a pegmatitic to micropegmatitic texture have a thin dark border composed of andradite, potassic-hastingsite, and dark micas and a thicker internal zone of poikilitic Ba-Sr-poor K-feldspar (Or 90.3 Ab 8.9 An 0.8 ), nepheline (Ne 74.9 Ks 19.4 Qz 5.7 to Ne 78.7 Ks 20.0 Qz 1.3 ), potassic-hastingsite, dark mica, andradite, scarce clinopyroxene (diopsidehedenbergite), and locally zoned microphenocrysts of Ba-Sr-rich K-feldspar (Or 75.6 Ab 21.7 An 2.7 ). Accessory fluorapatite, titanite, interstitial sodalite, and magnetite and secondary abundant Na-and K-rich zeolites, calcite, chlorite-group minerals, and possibly cancrinite have been identified.The textural and mineralogical characteristics of the SPSV show genetic links with the host malignite that belongs to the potassic alkaline series. The SPSV were formed from a residual syenitic melt (malignite) extracted from a parental tephritic magma. In the residual malignite, the concentration of primary crystals (apatite, clinopyroxene, Ba-Sr-rich K-feldspar, and nepheline) formed a crystal network (mush) with the open spaces occupied by small amounts of residual melt enriched in Al, Na, K, and volatiles and depleted in Ba and Sr. Deformation (by shear movements plus magmatic pressures) produced microfractures and fractures which were occupied by residual interstitial melt. In situ crystallization within these fractures resulted in the formation of the SPSV.

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Section: Geological Setting and Petrographymentioning

confidence: 99%

Section: Geochemistrymentioning

confidence: 99%