Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of lan
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Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of landslides at these islands with those at Tenerife, La Palma and El Hierro J. Acosta1,∗ , E. Uchupi2 , A. Muñoz1 , P. Herranz1 , C. Palomo1 , M. Ballesteros1 & ZEE Working Group3 1 Instituto
Español de Oceanografıa. f´ Grupo de Cartograff´ıa Multihaz. Corazon ´ de Mar´ıa, 8, 28002 Madrid Hole Oceanographic Institution, Woods Hole, MA 02543, USA 3 A.Carbo, M.Catalan ´ A. Muñoz-Mart´ın, Univ.Complutense, Madrid; J.Mart´ın-Davila, ´ ´ and J.A. Mar´ın, Real Observatorio de la Armada. S.Fernando, Cadiz; C´ F.Perez-Carrillo, C. Mate, de la Marina. ´ ´ Instituto Hidrogrrafico ´ C´ Cadiz. ∗ Corresponding author (E-mail:[email protected]) 2 Woods
Key words: multibeam mapping, Canary Island, avalanches, geomorphology
Abstract In this paper we discuss the results of a swath bathymetric investigation of the Canary archipelago offshore area. These new data indicate that volcanism is pervasive throughout the seafloor in the region, much more that would be suggested by the islands. We have mapped tens of volcanic edifices between Fuerteventura and Gran Canaria and offshore Tenerife, La Gomera, El Hierro and La Palma. Volcanic flows are present between Tenerife and La Gomera and salic necks dominate the eastern insular slope of La Gomera. This bathymetry also supports land geologic studies that indicate that the oceanic archipelago has acquired its present morphology in part by mass wasting, a consequence of the collapse of the volcanic edifices. In the younger islands, Tenerife, La Palma and El Hierro, the Quaternary (1.2 to 0.15 Ma) debris avalanches are readily recognizable and can be traced offshore for distances measured in tens of km. Off the older islands, Lanzarote, Fuerteventura, Gran Canaria and La Gomera (17.5 Ma >17.5 Ma
Gran Canaria Las Palmas Galdar Agaete NW SW R. Nublo
DA DA DA S DA DA
45 30 30 50 30 12
25 10 7 7 10 11
1100 300 200 400 250 150
9 Ma; 4.0-3.5 Ma 4.0-3.5 Ma 12?/14? Ma 15 Ma 4.0-3.5 Ma 4.03.5Ma
La Gomera I II III IV V VI VII VIII
DF? DF? DF? DF? DF? DF? DF? DF?
15 10 45 45 40 20 24 32
10 15 15 8 16 5 7 25
80 80 340 160 300 40 50 300
Tenerife Teno R. Garcia Icod Tigaiga Orotova Anaga Güimar A B C
DA DA DA DA DA DA DA DA DA DA
35 95 95 30 75 33 85 22 17 7
15 30 18 10 40 15 45 4 5 5
400 2200 1500 200 2200 500 2600 80 80 30
La Palma PV CN W-PN E-PN SC
DA DA DA DA DA
50 43 >40 40 50
35 30 15 11 35
1600 700 >300 400 1700
520 80
DA DA S DA Da
60 35 30 45 48
50 25 15 340
1700 1300 1300 350 1800
170
9/15-10/17;17-9 Ka
100 m, blocks 0.25 to 100 m in diameter, and blocks up to 100 m in diameter that were highly brecciated during the transport. The largest of the megablocks blocks (Roque Nublo Plateau) is 1200 m
long, 800 m wide and about 300 m thick (Mehl and Schmincke, 1999). Gran Canaria: Offshore Like the insular margin offshore Lanzarote and Fuerteventura, the margin of Gran Canaria may be mainly the creation of turbidity currents and hemipelagic d
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