Kaolin deposits along the Espinho-Albergaria-a-Velha metamorphic belt (NW Portugal): Structural geology and morphotectonics framework | Depósitos de caulino associados à faixa metamórfica de Espinho-Albergaria-a-Velha (NW de Portugal): Quadro geológico estrutural e morfotectónico

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Coelho, A. (Author) Other; Chaminé, Helder I. (Author) Other; Gomes, António Alberto (Author) FLUP; Fonseca, P.E. (Author) Other; Rocha, F. T. (Author) Other

Journal

Title: Cadernos do Laboratorio Xeoloxico de Laxe

Vol. 30

Pages: 89-120

ISSN: 0213-4497

Publisher: Seminario de Estudos Galegos

Indexing

ISI Web of Knowledge

Scopus - 2 Citations

Other information

Authenticus ID: P-007-QPT

Abstract (EN): This work synthesizes the present knowledge of the main occurrences of the kaolin deposits located near the Nw of Portugal and Galicia Atlantic shoreline, namely throughout the Espinho-Albergaria-a-Velha metamorphic belt. A geodynamic insight of the geotectonic and morphostructural control of the several outcropping kaolin deposits is presented in order to establish possible exploration guidelines of the georesources. The observation of a geological resources map of the Iberian Peninsula testifies that kaolin deposits exist all over the territory. Nevertheless, one may conclude that along the Nw Iberia this geological resource is well located, being fitted with major tectonic lineaments. The genesis of these deposits is dependent on several constraints, namely lithology, tectonics and morphology. A multidisciplinary approach was applied to the systematization of residual kaolin deposits located on the South of Porto city, as well on the vicinities of Aveiro region. The deposits that resulted from the hydrothermal alteration of granitic and gneissic rocks, located along the ante-Mesozoic crystalline bedrock of the Nw Iberia, were analysed. This georesource is related to high deformed metamorphic rocks, following particular tectonic corridors (NNW-SSE and NE-SW) and structural nods, related with the Porto-Coimbra-Tomar shear zone. The data obtained by photo-interpretation (at several scales) as well as the analysis of field geologic and morphological aspects allowed us to conclude that all the studied deposits were similarly geotectonic framework. All the studied deposits are located in a similar geologic and geomorphological background. The deposits are established at a maximum altitude of 250 m, on granitic or gneissic substratum, in which there are frequent tectonic nodes and shear zones. This way, we may conclude that the association of the geotectonical, geomorphological, mineralogical and palaeoenvironmental factors were responsible for the kaolin deposits formation, in a first stage by a hydrothermal action and afterwards through a continuous alteration originated by the action of meteoric geofluids.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 32