Palaeomagnetism in the Sines massif (SW Iberia) revisited: evidences for Late Cretaceous hydrothermal alteration and associated partial remagnetization

0397420 - GFÚ 2014 RIV GB eng J - Journal Article
Ribeiro, P. - Silva, P. F. - Moita, P. - Kratinová, Zuzana - Marques, F. O. - Henry, B.
Palaeomagnetism in the Sines massif (SW Iberia) revisited: evidences for Late Cretaceous hydrothermal alteration and associated partial remagnetization.
Geophysical Journal International. Roč. 195, č. 1 (2013), s. 176-191. ISSN 0956-540X. E-ISSN 1365-246X
Grant - others:FCT(PT) PTDC/CTE-GIX/098696/2008
Institutional support: RVO:67985530
Keywords : magnetic fabrics and anisotropy * magnetic mineralogy and petrology * palaeomagnetism applied to tectonics
Subject RIV: DE - Earth Magnetism, Geodesy, Geography
Impact factor: 2.724, year: 2013

This study revisits the palaeomagnetism of the Sines massif in the southwestern Iberian Margin (Portugal). The palaeomagnetic analysis was complemented by a comprehensive study of the magnetic mineralogy by means of rock magnetic measurements and petrographic observations. The overall dispersion of palaeomagnetic directions and their migration observed during stepwise demagnetizations have revealed the superposition of remanence components. We interpret this complex palaeomagnetic behaviour as related to the regional hydrothermalism associated with the last stages of Late Cretaceous magmatic activity. This environment favoured mineralogical alteration and a partial chemical remagnetization, giving in most samples a composite magnetization, which has been erroneously interpreted as the primary one in a previous study, then leading to a questionable model for Cretaceous Iberia rotation. Nonetheless, for some samples a single component has been isolated. Interesting rock magnetic properties and microscopic observations point to a well-preserved magnetic mineralogy for these samples, with magnetite clearly of primary origin.
Permanent Link: http://hdl.handle.net/11104/0225023