The Use of the GPS in the Identification of Fossil Shore Platforms and its Tectonic Deformation: an Example from the Northern Portuguese Coast.

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

Authors

Araújo, Maria da Assunção (Author) FLUP; Gomes, António Alberto (Author) FLUP

Journal

Title: Journal of Coastal Research

Vol. 56 No. 2

Pages: 688-692

ISSN: 0749-0208

Publisher: Coastal Education & Research Foundation, Inc.

Indexing

ISI Web of Knowledge - 0 Citations

ISI Web of Science

Scopus - 1 Citation

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Authenticus ID: P-003-QWN

Abstract (EN): Since more than 20 years we have the strong impression that recent tectonics may be active in the northern coastal zone of Portugal. This assumption is compatible with several recent studies on this matter. However, to prove the incidence of recent tectonics, we must find unequivocal deformation marks on the geomorphologic surfaces and on the Pleistocene deposits. Moreover, the deformed surfaces/deposits must be dated. This poses several difficulties as the marine deposits could not be dated by TL and OSL is quite problematic due to the small thickness of the beds and its iron cemented character. In order to overcome these issues, the study of Quaternary sedimentary deposits of the coastal zone of Porto was based upon a very detailed fieldwork and the accurate altitude definition with a GPS (Leica SR20). The use of a static reference to correct the data obtained with the mobile receptor (rover) allowed us to obtain a good precision on the altitude of significant geomorphologic points. This procedure allowed us to characterize the several marine platflorms along this coastline and perform sonic detailed profiles of rock outcrops emerging from sand beaches. Studying the geomorphologic development of present day platforms and its relationship with tidal levels, it was possible to identify some rare tiny platform remains standing above actual platforms (possible Flandrian) and also the more frequent and generally deposit bearing Eemien platform. This work suggests that the last interglacial marine deposits have suffered some tectonic disturbance as they appear at quite different altitudes along this coastal zone. Furthermore, its altitude accompanies the general trend of geomorphologic features: the higher coastal sectors generally bearing higher coastal deposits and higher fossil platforms.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5