Three‐Dimensional Magnetic Models of La Gomera (Canary Islands): Insights Into the Early Evolution of an Ocean Island Volcano

Abstract

An aeromagnetic data set from the island of La Gomera was studied through two inverse modeling approaches that produced complementary views of the inner structure of this volcanic island: (1) a variable magnetization model that identified the main lateral magnetization contrasts and (2) a constant magnetization model that imaged the main magnetic source by assuming that it was a uniformly magnetized body. The modeling reveals intense magnetizations beneath the northern part of La Gomera, which occupy an important portion of the northern submarine edifice, correspond well with outcrops of the submarine volcano (Basal Complex), and confirm that most of the magnetic signal revealed by aeromagnetic mapping in the Canary Islands is due to the intense magnetizations of the intrusive complexes (plutonic bodies and dike complexes) emplaced during the initial stages of growth of the volcanic edifices. The consistency of our models with the results of a previous gravimetric study suggests that these intrusive complexes are denser and more magnetic than the surrounding rocks. The location of the main magnetic source reinforces the interpretation, first suggested by geological evidence, that the submarine and early subaerial growth of La Gomera started to the north of the present island. The elongated shape of these intrusive complexes with a nearly E‐W strike agrees with the orientation of analogous structures on Tenerife and Gran Canaria, suggesting that the initial formation of the central islands of the Canary Archipelago was controlled by a set of regional fractures in a strike‐slip tectonic framework.

Insights into the Magmatic Feeding System of the 2021 Eruption at Cumbre Vieja (La Palma, Canary Islands) Inferred from Gravity Data Modeling

“…Potential field methods have been widely used to study volcanic islands to obtain 3D models of the inner volcanic systems to image magma intrusion beneath the surface. This allows us to delineate the main volcanic structures and constrain the locations of dense intrusive basaltic and ultramafic bodies, as well as geothermal areas, related to the heat flow along the plumbing system (e.g., [3][4][5][6][7][8][9][10]).…”

Strain Pattern and Kinematics of the Canary Islands from GNSS Time Series Analysis

“…The NNW-SSE orientation matches the orientation of stresses obtained by [33] using data from the moderate Mw 5.0 earthquake that occurred between Tenerife and Gran Canaria in 1989 and agrees with the orientation of the regional compression model described by [36,37] for the archipelago. Recent aeromagnetic studies by [38][39][40] in the central islands of the archipelago revealed elongated anomalies with E-W (Tenerife and La Gomera) and ENE-WSW (Gran Canaria) orientations. Furthermore, [39] accounted for the intrusive body found in the submarine edifice of Gran Canaria, which has an ENE-WSW orientation that coincides with the aforementioned fracture suggested by [28].…”

“…More recently, refs. [39,40] suggested that such an orientation could be responsible for the ascent and emplacement of magmas in the early formation phases of the central islands of the archipelago. Moreover, such a deformation pattern with an east-west orientation in the central islands is consistent with the existence of the major tectonic feature that connects the Trans-Alboran Fault System with the Mid-Atlantic Ridge, as suggested by [24] (see Figure 1).…”

“…The analysis and modelling of aeromagnetic anomalies in Tenerife [38] and La Gomera [40] revealed that E-W tectonic features controlled the emplacement of magmas during the early formation of these islands since the most important intrusive complexes formed at the initial stages of their volcanic history are elongated in that direction. This implies that the E-W tectonic lineaments inferred from the present GNSS study represent long-lived tectonic features that have been active during the entire history of the Canary archipelago, from the Miocene to the present.…”