The Mechanical Nature of the Lithosphere Beneath the Eastern Central Atlantic Hotspots. (13th March 2023)

• Record Type: Journal Article
• Authors: Jiménez‐Díaz, Alberto; Negredo, Ana M.; Kirby, Jon F.; Sánchez‐Pastor, Pilar; Fullea, Javier; Ruiz, Javier; Pérez‐Gussinyé, Marta; Yu, Chuanhai
• Is Part Of: Geochemistry, geophysics, geosystems. Volume 24:Number 3(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-13
• Subjects: hotspots -- effective elastic thickness -- lithospheric structure; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 550.5
• DOI: 10.1029/2022GC010608
• Languages: English
• ISSNs: 1525-2027

Abstract

Abstract: The Eastern Central Atlantic (ECA) region includes the Azores, Canary, Cape Verde, Great Meteor, and Madeira hotspots. These hotspots exhibit a large variety of characteristics and are rooted in the lithosphere ranging in age from newly created at the Mid Atlantic Ridge to Jurassic at the NW Africa Atlantic margin. Therefore, the ECA region represents an excellent scenario to investigate in an integrated way the effects of hotspots on the mechanical structure of oceanic lithosphere. Here, we calculate the effective elastic thickness ( T e ) of the lithosphere from an analysis of gravity and topography. Azores hotspot is characterized by a T e < 10 km, whereas the Great Meteor, Cape Verde, and Madeira hotspots have intermediate T e (15–30 km) values. In contrast, the Canary hotspot is characterized by a much higher T e (>50 km), forming the largest and most prominent mechanical feature in the ECA. All the hotspots except Canary show standard elastic thickness values when compared to average values for the same age lithosphere and to other oceanic areas in the world. The high strength of the Canary hotspot may be related to the highly depleted mantle composition in the area. The comparison between the elastic thickness distribution and the upper mantle seismic velocity structure shows no correlation between the T e estimated at the ECA hotspots (with the exception of Azores) and the presence of low shear‐wave velocity anomalies in the underlying mantle. This lack of correlation suggests a negligible effect of upper mantle temperature anomalies on the flexure of the ECA region. Plain Language Summary: The upwelling of hot mantle material can modify drastically the thermal and mechanical properties of the rigid outer layer of the Earth (the lithosphere). In this study, we investigate the mechanical effects of the Azores, Canary, Cape Verde, Great Meteor, and Madeira hotspots on the oceanic lithosphere in the Eastern Central Atlantic. To do so, we use gravity and elevation data to analyze the spatial distribution of the effective elastic thickness of the lithosphere in this region, which is a proxy for the lithospheric strength. All of these hotspots except Canary show standard elastic thickness values when compared to the average thickness of the same age lithosphere. In contrast, the lithosphere in the Canary region is much stronger, and this high strength may be related to the nature of the underlying mantle. Finally, the presumed presence of hot mantle beneath these hotspots does not produce any weakening of the overlying lithosphere. Key Points: The mechanical effects of the Eastern Central Atlantic hotspots are investigated The Azores, Cape Verde, Great Meteor, and Madeira hotspots show standard T e values The Canary hotspot is the notable exception, with a complex pattern of T e