Publication: Las rocas ultramáficas alcalinas del Jable de Las Salinas, Fuerteventura, Islas Canarias
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1990
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Sociedad Geológica de España
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Abstract
En este trabajo se aborda el estudio geológico, petrológico y geoquímico de las rocas que forman el núcleo de un complejo ultramáfico-carbonatítico que aflora a lo largo de la costa del Jable de Salinas en el Macizo de Amanay (Fuerteventura, Islas Canarias).
Este complejo, de naturaleza subvoIcánica, se emplazó imbricándose con los episodios intrusivos de las mallas
filonianas características de los Complejos Basales canarios. Está atravesado por un denso "net- work" de
naturaleza feldespática y en determinadas zonas carbonatíticas y rocas ya relacionadas con procesos de fenitización, fundamentalmente flogopitizaciones.
Las rocas ultramáficas a cuyo estudio está dedicado este trabajo están compuestas casi exclusivamente por salita, kaersutita y grandes proporciones de apatito y minerales opacos, con total ausencia de olivino, feldespatos
y feldespatoides.
Geoquímicamente, destacan por su carácter fuertemente subsaturado: porcentajes muy bajos de Si02 y altos
contenidos de Fe total, Ti02 y P20S. Sus características texturales, mineralógicas y químicas sugieren que han sido
originadas por inmjscibilidad líquida.
In this paper the geological, petrological and geochemical features of the alkaline pyroxenites and anphibololites of an ultramafic-carbonatite complex are studied. These rocks crop out in the SW coast of Fuerteventura (Canary Islands), in the area known as Amanay Massif. This subvolcanic complex was emplaced at the same time as the late basaltic dyke swarms of the Basal Complex and was intruded by a dense net-work mainly feldspathic and in sorne places also carbonatitic. Rocks related to fenitization processes are also presento The ultramafic rocks are pyroxenites and amphibololites composed mainly by: salite, kaersutite, apatite, magnetite and ilmenite. One of their most significant characteristics is the modal abundance of apatite and Fe-Ti oxides and the total lack of olivine, feldspars and feldspathoids. GeochemicaIly they present an alkaline and subsaturate trend with very low contents of Si02 and high values of total Fe, Ti02 and P20S. The textural, mineralogical and chemical character of the rocks indicate that they were probably formed by liquid inmiscibility processes.
In this paper the geological, petrological and geochemical features of the alkaline pyroxenites and anphibololites of an ultramafic-carbonatite complex are studied. These rocks crop out in the SW coast of Fuerteventura (Canary Islands), in the area known as Amanay Massif. This subvolcanic complex was emplaced at the same time as the late basaltic dyke swarms of the Basal Complex and was intruded by a dense net-work mainly feldspathic and in sorne places also carbonatitic. Rocks related to fenitization processes are also presento The ultramafic rocks are pyroxenites and amphibololites composed mainly by: salite, kaersutite, apatite, magnetite and ilmenite. One of their most significant characteristics is the modal abundance of apatite and Fe-Ti oxides and the total lack of olivine, feldspars and feldspathoids. GeochemicaIly they present an alkaline and subsaturate trend with very low contents of Si02 and high values of total Fe, Ti02 and P20S. The textural, mineralogical and chemical character of the rocks indicate that they were probably formed by liquid inmiscibility processes.