Gravimetric and magnetic fabric study of the Sintra Igneous complex: laccolith-plug emplacement in the Western Iberian passive margin

Pedro Terrinha, Emilio L. Pueyo, Aitor Aranguren, José Carlos Kullberg, Maria Carla Kullberg, Antonio Casas-Sainz, Maria do Rosário Azevedo

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The geometry and emplacement of the ~ 96 km2, Late Cretaceous Sintra Igneous complex (SIC, ca. 80 Ma) into the West Iberian passive margin is presented, based on structural data, gravimetric modeling, and magnetic fabrics. A granite laccolith (~ 76 km2, < 1 km thick, according to gravimetric modeling) surrounds a suite of gabbro–diorite–syenite plugs (~ 20 km2, ~ 4 km deep) and is encircled by cone sheets and radial dykes. Anisotropy of Magnetic Susceptibility was interpreted from 54 sites showing fabrics of para- and ferro-magnetic origin. Most fabrics can be interpreted to have a magmatic origin, according to the scarcity of solid-state deformation in most part of the massif. Magnetic foliations are shallowly dipping in the granite laccolith and contain a sub-horizontal ENE–WSW lineation. The gabbro–syenite body displays concentric magnetic foliations having variable dips and steeply-plunging lineations. The SIC can be interpreted to be intruded along an NNW–SSE, 200 km-long fault, perpendicular to the magnetic lineation within the laccolith, and was preceded by the intrusion of basic sills and plugs. The SIC intruded the Mesozoic series of the Lusitanian Basin during the post-rift, passive margin stage, and its geometry was only slightly modified during the Paleogene inversion that resulted in thrusting of the northern border of the intrusion over the country rocks.

Original languageEnglish
Pages (from-to)1807-1833
Number of pages27
JournalInternational Journal Of Earth Sciences
Volume107
Issue number5
DOIs
Publication statusPublished - 1 Jul 2018

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laccolith
magnetic fabric
passive margin
lineation
emplacement
foliation
granite
geometry
magnetic anisotropy
country rock
sill
Paleogene
modeling
dip
Cretaceous
basin
fabric

Keywords

  • Anisotropy of magnetic susceptibility
  • Cretaceous alkaline magmatism
  • Gravimetry
  • Sintra
  • West Iberia margin

Cite this

Terrinha, Pedro ; Pueyo, Emilio L. ; Aranguren, Aitor ; Kullberg, José Carlos ; Kullberg, Maria Carla ; Casas-Sainz, Antonio ; Azevedo, Maria do Rosário. / Gravimetric and magnetic fabric study of the Sintra Igneous complex: laccolith-plug emplacement in the Western Iberian passive margin. In: International Journal Of Earth Sciences. 2018 ; Vol. 107, No. 5. pp. 1807-1833.
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Gravimetric and magnetic fabric study of the Sintra Igneous complex: laccolith-plug emplacement in the Western Iberian passive margin. / Terrinha, Pedro; Pueyo, Emilio L.; Aranguren, Aitor; Kullberg, José Carlos; Kullberg, Maria Carla; Casas-Sainz, Antonio; Azevedo, Maria do Rosário.

In: International Journal Of Earth Sciences, Vol. 107, No. 5, 01.07.2018, p. 1807-1833.

Research output: Contribution to journalArticle

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AU - Terrinha, Pedro

AU - Pueyo, Emilio L.

AU - Aranguren, Aitor

AU - Kullberg, José Carlos

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AU - Casas-Sainz, Antonio

AU - Azevedo, Maria do Rosário

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