Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

Druet, M.; Muñoz-Martı́n, A.; Granja-Bruña, José Luis; Carbó-Gorosabel, A.; Llanes, P.; Catalán, Manuel; Maestro, Adolfo; Bohoyo, Fernando; Martín-Dávila, J.

doi:10.1080/17445647.2019.1644214

Cited by 8 publications

(5 citation statements)

References 37 publications

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“…The south central area of the map shows a dipolar anomaly (around 11.5°W longitude and 42.4°N latitude) that correlates with the Galicia Bank region (the highest and biggest of the seamounts, see Figure 1 for location), but slightly shifted towards the southeast with respect to the highest area (See minimum bathymetry point in the Magnetic anomaly map over the shaded relief model, Main Map). The same displacement to the southeast is also observed in the corresponding Bouguer Anomaly map (Druet et al, 2019), associated to a relatively thicker continental crust in this area of the seamounts region (Druet et al, 2018). The NE-SW trending positive anomaly that borders the seamounts region to the northwest and north can be correlated to the existence of a peridotite ridge to the northwest of the seamounts region (e.g.…”

Section: Brief Magnetic Anomaly Map Description and Interpretationsupporting

confidence: 72%

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Magnetic anomalies of the NW Iberian continental margin and the adjacent abyssal plains

et al. 2020

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The NW Iberian margin is a hyperextended continental margin, formed during the opening of the North Atlantic Ocean, where a subsequent partial tectonic inversion has undergone during the Alpine Orogeny. This succession of tectonic episodes determines the magnetic signature of the margin. The Spanish Exclusive Economic Zone Project has carried out seven one-month cruises between 2001 and 2009. To extend and densify the spatial coverage, we have used data from the World Digital Magnetic Anomaly Map. Here, we describe the methodology used for the acquisition and data processing of the magnetic field data. The use of diverse instrumentation, a non-complete external field's cancelation, and the use of different magnetic core field models, contributed to the total error budget. To reduce it, we have used a leveling algorithm which minimizes all these contributions. Finally, a statistical analysis was applied using crossover residuals, showing a resolution better than 28 nT.

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Section: Brief Magnetic Anomaly Map Description and Interpretationsupporting

confidence: 72%

“…Inset shows the location of the study area represented on the Main Map. Modified from Druet et al (2019).…”

Section: Data Acquisition and Processingmentioning

confidence: 99%

Magnetic anomalies of the NW Iberian continental margin and the adjacent abyssal plains

et al. 2020

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“…Published works investigating the Mesozoic rift domains in the WIM distinguish two sectors. In the northern sector, the continental hyperextended crust stretches for more than 300 km and the exhumed mantle domain extends westwards of the GB (Druet et al, 2019). In the southern sector, contrastingly, the hyperextended crust extends for 200 km before reaching the same transition (Pedrera et al, 2017).…”

Section: Crustal Structure and Domains Of The Wimmentioning

confidence: 97%

“…It developed conjugate to the Newfoundland margin during the Mesozoic rifting (Péron-Pinvidic and Manatschal, 2009). Its crustal structure, although debated in minor aspects, is formed by a series of structural domains from East to West (e.g., Péron-Pinvidic and Manatschal, 2009;Ramos et al, 2016;Druet et al, 2019;Merino et al, 2021) and includes a Variscan basement (Schulmann et al, 2022). The segmentations observed within the WIM resulted from the northward migration of extension and successive late Jurassic to early Cretaceous extensional phases (e.g., Malod and Mauffret, 1990;Péron-Pinvidic et al, 2007;Tucholke et al, 2007;Merino et al, 2021).…”

Section: Crustal Structure and Domains Of The Wimmentioning

confidence: 99%

Offshore seismicity clusters in the West iberian Margin illustrated by two decades of events

Fernández‐Viejo

Fernández

Cadenas

2023

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Abstract. An analysis of two decades (2003–2022) of seismicity recorded by the Spanish and Portuguese seismic networks along the West Iberian passive margin has resulted in a better understanding of the distribution of moderate seismic activity in this intraplate submarine area. The study provides a precise trend of specific alignments inferred from the density maps of seismicity, giving an accurate depiction of event distribution along two wide stripes that extend 700 km long through the ocean floor in a WNW-ESE direction. These bands are parallel to the Africa-Eurasia plate boundary but are distinctly separated from its related seismicity by approximately 300 km and 700 km, respectively. This is a sufficient distance to be considered as intraplate activity. When trying to relate this seismicity to structural and geophysical features, a conclusive picture doesn't emerge. The earthquakes occur indiscriminately across thinned continental, hyperextended, and exhumed mantle rift domains. They fade out in the proximity of undisputed oceanic crust, but some events extend beyond. The hypocentral depths signal a considerable amount of events nucleating in the upper mantle. The focal mechanisms, although scarce, are predominantly strike-slip. Considering these observations, hypothesis ranging from subduction initiation, development of strained corridors or local structures of the margin, have been discussed in order to explain this relatively anomalous seismicity. However, some of them do not portray convincing arguments, while others are too unspecific. None of them are flawless, suggesting that several factors may be at play. Despite being one of the most probed passive margins in the world, the present geodynamical status of the West Iberian Margin manifested in its modern seismicity remains unknown. Interpreting this data within a global tectonic plate framework, together with the potential addition of seafloor seismometers, may provide the key to understanding this activity along one of the most archetypical margins of the Atlantic Ocean.

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“…The gravity method can supplement sources of information for the completion and interpretation of geological maps. This geophysical survey technique measures variations in the gravitational field related to changes in subsurface densities, geometric distribution, and depth of rocks or any crustal bodies of interest (Druet et al, 2019;Kearey et al, 2002). Mapping with gravity method is done at various scales depending on the specific objectives and the study region.…”

Section: Introductionmentioning

confidence: 99%

Bouguer Anomaly of Central Cebu, Philippines

et al. 2020

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Cebu Island in Central Philippines consists of a Cretaceous basement complex capped by mostly Tertiary sedimentary units. Recent mapping conducted in Central Cebu revealed limited exposures of lithologies, especially those comprising the basement complex. The gravity method was utilized to generate Bouguer anomaly maps for Central Cebu. These geophysical maps provide the first images of the subsurface extent of the basement units. A prominent nearly circular gravity anomaly high is consistently observed in the Bouguer anomaly maps coinciding with the location of dense basement and intrusive rocks. However, field mapping revealed the very limited surface exposure of these units. The gravity highs recognized in the residual anomaly maps may correspond to the larger extent of the intrusive units at depth. The broad gravity high observed in the regional anomaly map may define the extent of the subsurface distribution of the Cretaceous basement complex.

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Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

Cited by 8 publications

References 37 publications

Magnetic anomalies of the NW Iberian continental margin and the adjacent abyssal plains

Magnetic anomalies of the NW Iberian continental margin and the adjacent abyssal plains

Offshore seismicity clusters in the West iberian Margin illustrated by two decades of events

Bouguer Anomaly of Central Cebu, Philippines

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