Blanco-Montenegro, I. and González Montesinos, Fuensanta and Garcia, Alicia and Vieira, Ricardo and Villalain, J.J. (2005) Paleomagnetic determinations on Lanzarote from magnetic and gravity anomalies: Implications for the early history of the Canary Islands. Journal of Geophysical Research-Solid Earth, 110 (B12). ISSN 0148-0227
Restricted to Repository staff only until 2020.
The Bouguer and aeromagnetic anomaly maps of Lanzarote show a gravity high and a dipolar magnetic anomaly over the central part of the island, indicating one isolated source. Assuming that the structure responsible for both anomalies is the same, a methodology has been designed to estimate the total magnetization vector of the source, which is interpreted as a large intrusive body (mafic core) positioned as a result of magma rising to the surface during the early stages of growth of Lanzarote. Considering its geometry to be known from a previous three-dimensional (3-D) gravity model, the approach proposed in this paper is based on the delineation of magnetic contacts through analysis of the horizontal gradient of the reduced-to-the-pole anomaly map, comparison between the gravity and the pseudogravity anomalies, and 3-D forward magnetic modeling. The total magnetization vector obtained by this method is defined by a module of 4.5 A m(-1) and a direction D = -20 degrees and I = 30 degrees. Comparing the paleomagnetic pole, obtained from this direction, with the apparent polar wander path of Africa for the last 160 Myr, it is concluded that the main component of the total magnetization vector is probably a primary natural remanent magnetization (NRM) which could have been acquired between 60 and 100 Ma. This result suggests that the emplacement of magmas at shallow depths linked to the beginning of volcanism in Lanzarote took place during the Upper Cretaceous, thus providing the first evidence of a timeline for the early formative stages of this volcanic island.
|Uncontrolled Keywords:||Geomagnetic Polarity History; Potassium-Argon Ages; La-Palma; Gran-Canaria; Volcanic Stratigraphy; Central Atlantic; Oceanic Island; Fuerteventura; Evolution; Tenerife|
|Subjects:||Sciences > Geology > Seismology|
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|Deposited On:||11 Jul 2012 12:46|
|Last Modified:||17 Jul 2012 09:36|
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