Ribeira de Fanhões, Fanhões, Loures, Lisbon, Portugali

Regional Level Types
Ribeira de Fanhões	Volcanic Complex
Fanhões	Civil Parish
Loures	Municipality
Lisbon	District
Portugal	Country

This locality is included in the Lisbon Volcanic Complex, formed 72 million years ago by several important volcanic episodes. The outcrops of the LVC can be seen between Lisbon and Mafra, about 40 km to the north, showing basaltic sheets, tuffs, pyroclasts, volcanic breccias, etc., accompanied by a dense net of eruptive dykes.

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Outcrop of Fanhões, at the Casaínhos Stream, south of the locality of Fanhões.

In the area near Fanhões, specifically in the bed of the stream of the same name, a few dozen meters upstream from the confluence with the Casaínhos Stream, the following sequence can be observed:

1 - Compact limestones with rudists and foraminifera (Upper Cenomanian), heavily paleokarstified (Bica Formation).
2 - Carbonate conglomerate, containing elements from the previous level, as well as gray limestone clasts with microbial crusts and evidence of subaerial exposure and pedogenesis (Fanhões Conglomerate).
3 - By combining the observation of this site with nearby outcrops, to the east and west, it is concluded that the conglomerate is overlain by pyroclastic layers and basaltic flows of the Lisbon Volcanic Complex.

This site is the only known location in the Lusitanian Basin where this conglomerate occurs between the limestones with rudists and the Lisbon Volcanic Complex. Along the Casaínhos Stream, to the west, various features of educational interest can be observed in the volcanic deposits and sand dykes cutting through pyroclasts.

Note: The above text was freely translated and adapted from the LNEG geoPortal (https://geoportal.lneg.pt).

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