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Abstract:

In this study, we compare the major- and trace-element compositions of olivine, garnet, and clinopyroxene that occur as single crystals (142 grains), with those derived from xenoliths (51 samples) from six kimberlites in the Lucapa area, northeastern Angola: Tchiuzo, Anomaly 116, Catoca, Alto Cuilo-4, Alto Cuilo-63 and Cucumbi-79. The samples were analyzed using electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results suggest different paragenetic associations for these kimberlites in the Lucapa area. Compositional overlap in some of the macrocryst and mantle xenolith samples indicates a xenocrystic origin for some of those macrocrysts. The presence of mantle xenocrysts suggests the possibility of finding diamond. Geothermobarometric calculations were carried out using EPMA data from xenoliths by applying the program PTEXL.XLT. Additional well calibrated single-clinopyroxene thermobarometric calculations were also applied. Results indicate the underlying mantle experienced different equilibration conditions. Subsequent metasomatic enrichment events also support a hypothesis of different sources for the kimberlites. These findings contribute to a better understanding of the petrogenetic evolution of the kimberlites in northeastern Angola and have important implications for diamond exploration. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Registro:

Documento: Artículo
Título:Major- and trace-element compositions of indicator minerals that occur as macro- and megacrysts, and of xenoliths, from kimberlites in Northeastern Angola
Autor:Robles-Cruz, S.E.; Melgarejo, J.C.; Galí, S.; Escayola, M.
Filiación:Department of Crystallography,Mineralogy and Mineral Deposits, University of Barcelona, Barcelona, 08028, Spain
CONICET-IDEAN Institute of Andean Studies, Andean Tectonic Laboratory, University of Buenos Aires, Buenos Aires, C1033AAJ, Argentina
Palabras clave:Angola; Clinopyroxene; Diamond; Garnet; Kimberlite; Mantle xenoliths; Nd isotopes; Olivine; REE; Sm; Thermobarometry
Año:2012
Volumen:2
Número:4
Página de inicio:318
Página de fin:337
DOI: http://dx.doi.org/10.3390/min2040318
Título revista:Minerals
Título revista abreviado:Minerals
ISSN:2075163X
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_2075163X_v2_n4_p318_RoblesCruz

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Citas:

---------- APA ----------
Robles-Cruz, S.E., Melgarejo, J.C., Galí, S. & Escayola, M. (2012) . Major- and trace-element compositions of indicator minerals that occur as macro- and megacrysts, and of xenoliths, from kimberlites in Northeastern Angola. Minerals, 2(4), 318-337.
http://dx.doi.org/10.3390/min2040318
---------- CHICAGO ----------
Robles-Cruz, S.E., Melgarejo, J.C., Galí, S., Escayola, M. "Major- and trace-element compositions of indicator minerals that occur as macro- and megacrysts, and of xenoliths, from kimberlites in Northeastern Angola" . Minerals 2, no. 4 (2012) : 318-337.
http://dx.doi.org/10.3390/min2040318
---------- MLA ----------
Robles-Cruz, S.E., Melgarejo, J.C., Galí, S., Escayola, M. "Major- and trace-element compositions of indicator minerals that occur as macro- and megacrysts, and of xenoliths, from kimberlites in Northeastern Angola" . Minerals, vol. 2, no. 4, 2012, pp. 318-337.
http://dx.doi.org/10.3390/min2040318
---------- VANCOUVER ----------
Robles-Cruz, S.E., Melgarejo, J.C., Galí, S., Escayola, M. Major- and trace-element compositions of indicator minerals that occur as macro- and megacrysts, and of xenoliths, from kimberlites in Northeastern Angola. Minerals. 2012;2(4):318-337.
http://dx.doi.org/10.3390/min2040318