Composition and crystalline temperature of nepheline from rocks of an ijolite-melteigite series

Kononova, V. A.; Organova, N. I.; Lomeyko, Ye. I.

doi:10.1080/00206816709474548

Cited by 2 publications

(1 citation statement)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Transparent colorless grains were found in the EU, whereas it is replaced by zeolite-group minerals and locally also by secondary sodalite in a groundmass of K-feldspar in the IU and the SPSV. The compositions of nepheline (Table 7), Ne 74.9 Ks 19.4 Qz 5.7 to Ne 78.7 Ks 20.0 Qz 1 , were calculated according to Kononova et al (1967). The analyzed grains are rich in Ca (1.13 to 2.17 wt.% CaO), as in the nepheline monzonite, nepheline diorite, and theralite from the Messum alkaline complex, Namibia (Blancher et al 2010).…”

Section: Nephelinementioning

confidence: 99%

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

et al. 2016

View full text Add to dashboard Cite

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.

show abstract

Section: Nephelinementioning

confidence: 99%