First evidence of lamprophyric magmatism within the Subbetic Zone (Southern Spain)
Puga, Encarnación (Instituto Andaluz de Ciencias de la Tierra)
Beccaluva, Luigi (Università di Ferrara. Dipartimento di Scienze della Terra)
Bianchini, Gianluca (CNR - Instituto di Geoscienze e Georisorse (IGG))
Díaz de Federico, Antonio (Instituto Andaluz de Ciencias de la Tierra)
Díaz Puga, Miguel Ángel (Universidad de Almería. Departamento de Hidrogeología)
Álvarez-Valero, Antonio M. (Instituto Andaluz de Ciencias de la Tierra)
Galindo Zaldívar, Jesús (Universidad de Granada. Departamento de Geodinámica)
Wijbrans, Jan (Vrije Universiteit Amsterdam)

Data:	2010
Resum:	Two drillings carried out at Cerro Prieto (Province of Málaga), together with additional geophysical data, revealed the existence of an igneous body formed of rock-types previously unknown in the Subbetic zone. The recovered rocks, emplaced under hypoabyssal conditions, are predominantly porphyric, containing olivine, diopside and TiO2-rich phlogopite phenocrysts (up to 1-2 mm in size) within a micro-to-hypocrystalline groundmass componed of alkali-feldspar, diopside, phlogopite and abundant magnetite, and could be classified as "alkali minettes" lamprophyres. They contain numerous xenocrysts corroded by the magma and centimetric ultrafemic xenoliths deriving from the mantle. Clinopyroxenes yield crystallisation temperatures from about 1150 to 1320º C and pressures ranging from about 4 to 17 kbar, suggesting 50 km as the minimum depth of the magma sources. The chemical compositions of these lamprophyres are similar to intra plate alkali-basalts, derived from oceanic-island-basaltic-type highly metasomatized mantle sources. 40Ar/39Ar dating of a phlogopite mineral separate gave an age of 217±2. 5 Ma. However, these rocks are more similar to the Permian alkaline lamprophyres in the Spanish Central System than to the Mesozoic dolerites and basalts widespread throughout the Subbetic Zone. We propose that the Cerro Prieto subvolcanic event represents the onset of a widespread magmatic phase induced by the post-Hercynian extensional tectonic activity that also affected the whole South-Iberian Paleomargin, within a geodynamic context that ultimately led to the opening of the Atlantic and the Neotethys oceans, accompanied by intrusion of basic magmas along their continental margins.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Lamprophyric magmatism ; Metasomatized mantle ; Subbetic Zone ; Betic Cordilleras ; Southern Spain
Publicat a:	Geologica acta, Vol. 8, Núm. 2 (Junio 2010) , p. 111-130, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/202688
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001526
DOI: 10.1344/105.000001526

22 p, 1.5 MB

El registre apareix a les col·leccions:
Articles > Articles publicats > Geologica acta
Articles > Articles de recerca