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GEOREF RECORD

Petrography, mineralogy, and origin of the syenite pegmatitic segregation veins from La Pena alkaline complex, Mendoza, Argentina

Diego Sebastian Pagano, Miguel Angel Galliski, Maria Florencia Marquez-Zavalia, Milan Novak and Radek Skoda
Petrography, mineralogy, and origin of the syenite pegmatitic segregation veins from La Pena alkaline complex, Mendoza, Argentina (in Mineralogy, crystallography, petrology, economic geology, geochemistry; pegmatite special issue dedicated to Drs. William B. (Skip) Simmons and Karen L. Webber, Alexander U. Falster (prefacer) and Pietro Vignola (prefacer))
The Canadian Mineralogist (July 2016) 54 (4): 803-825

Abstract

The syenite pegmatitic segregation veins (SPSV) of the Early Miocene La Pena 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 (sub 90.3) Ab (sub 8.9) An (sub 0.8) ), nepheline (Ne (sub 74.9) Ks (sub 19.4) Qz (sub 5.7) to Ne (sub 78.7) Ks (sub 20.0) Qz (sub 1.3) ), potassic-hastingsite, dark mica, andradite, scarce clinopyroxene (diopside-hedenbergite), and locally zoned microphenocrysts of Ba-Sr-rich K-feldspar (Or (sub 75.6) Ab (sub 21.7) An (sub 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.


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 54
Serial Issue: 4
Title: Petrography, mineralogy, and origin of the syenite pegmatitic segregation veins from La Pena alkaline complex, Mendoza, Argentina
Title: Mineralogy, crystallography, petrology, economic geology, geochemistry; pegmatite special issue dedicated to Drs. William B. (Skip) Simmons and Karen L. Webber
Author(s): Pagano, Diego SebastianGalliski, Miguel AngelMarquez-Zavalia, Maria FlorenciaNovak, MilanSkoda, Radek
Author(s): Falster, Alexander U.prefacer
Author(s): Vignola, Pietroprefacer
Affiliation: Centro Cientifico Tecnologico-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Instituto Argentino de Nivologia, Glaciologia y Ciencias Ambientales, Mendoza, Argentina
Affiliation: Maine Gem and Mineral Museum, Bethel, ME, United States
Pages: 803-825
Published: 201607
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 48
Accession Number: 2017-080332
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 10 tables, sketch map
S32°41'34" - S32°41'34", W68°59'48" - W68°59'48"
Secondary Affiliation: Universidad Nacional de San Luis, ARG, ArgentinaUniversidad Nacional de Cuyo, ARG, ArgentinaMasaryk University, CZE, Czech Republic
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201742
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