New data on the geological structure of the junction of the Cape Verde Rise, Cape Verde Abyssal Basin, and Bathymetrists Seamounts (Central Atlantic Ocean)

Skolotnev, S. G.; Turko, N. N.; Sokolov, S. Yu.; Peyve, A. A.; Tsukanov, N. V.; Kolodyazhnyi, S. Yu.; Чамов, Н. П.; Baramykov, Yu. E.; Ponomarev, A. S.; Ефимов, В. М.; Eskin, A. E.; Petrova, V. V.; Golovina, L. A.; Lavrushin, V. Yu.; Letyagina, Ekaterina; Shevchenko, E. P.; Krivosheya, Konstantin; Zotov, Leonid

doi:10.1134/s1028334x07070124

“…Turko, Yu.E. Baramykov, and A.S. Ponomarev using bathymetric data obtained during Cruise 23 of the R/V Akademik Nikolai Strakhov (Skolotnev et al, 2007). (1) Location and number of the deep sea drilling program (DSDP) borehole, (2) dredging stations of Cruise 23 of the R/V Akademik Nikolai Strakhov, (3) Mesozoic magnetic lineations and their numbers, (4) western boundary of the Jurassic magnetic quiet zone according to Hayes (1975), (5) Guinea Fracture Zone (Jones, 1987), and (6) Fig.…”

Section: Petrographic Descriptionmentioning

confidence: 99%

“…1). The seamount is approxi mately 3500 m high and is an extinct volcano with a middle Eocene carbonate bank on its flattened top (Skolotnev et al, 2007). Rock samples were recovered at two stations, lower (S2303; 9°13.1′N, 21°15.7′W; depth 2300-2400 m) and upper (S2304; 9°12.9′N, 21°16.8′W; depth 1700-2100 m).…”

Section: Introductionmentioning

confidence: 99%

Origin of submarine volcanism at the eastern margin of the central atlantic: Investigation of the alkaline volcanic rocks of the carter seamount (Grimaldi Seamounts)

Skolotnev

¹

,

Petrova

²

,

Peyve

³

2012

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This paper addresses the composition, geochemistry, isotopic characteristics, and age of rocks from the Carter Seamount of the Grimaldi seamount group at the eastern margin of the Central Atlantic. The age of the seamount was estimated as 57-58 Ma. Together with other seamounts of the Grimaldi system and the Nadir Seamount, it forms a "hot line" related to the Guinea Fracture Zone, which was formed during the late Paleocene pulse of volcanism. The Carter Seamount is made up of olivine melilitites, ankaramites, and analcime bearing nepheline tephrites, which are differentiated products of the fractional crystallization of melts similar to an alkaline ultramafic magma. The volcanics contain xenoliths entrained by melt at different depths from the mantle, layer 3 of the oceanic crust, which was formed at 113-115 Ma, and earlier magma chambers. The rocks were altered by low temperature hydrothermal solutions. The parental melts of the vol canics of the Carter Seamount were derived at very low degrees of mantle melting in the stability field of gar net lherzolite at depths of no less than 105 km. Anomalously high Th, Nb, Ta, and La contents in the volca nics indicate that a metasomatized mantle reservoir contributed to the formation of their primary melts. The Sr, Pb, and Nd isotopic systematics of the rocks show that the composition of the mantle source lies on the mixing line between two mantle components. One of them is a mixture of prevailing HIMU and the depleted mantle, and the other is an enriched EM2 type mantle reservoir. These data suggest that the formation of the Carter Seamount volcanics was caused by extension related decompression melting in the Guinea Fracture Zone of either (1) hot mantle plume material (HIMU component) affected by carbonate metasomatism or (2) carbonated basic enclaves (eclogites) ubiquitous in the asthenosphere, whose isotopic characteristics cor responded to the HIMU and EM2 components. In the former case, it is assumed that the melt assimilated during ascent the material of the metasomatized subcontinental mantle (EM2 component), which was incor porated into the oceanic lithospheric mantle during rifting and the breakup of Pangea.

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“…Evidence for fracture zone offsets is documented by magnetic lineations and gravity anomalies (Figure 3; Hayes and Rabinowitz, 1975;Dash et al, 1976;Williams et al 1990;Verhoef et al 1991;Roest et al 1992;. Additionally brittle deformation through normal, reverse and transverse faults has formed horst and graben structures on the Cape Verde Rise (Figure 3b; Efimov & Skolotnev, 2006;Skolotnev et al, 2007;. The Cretaceous ocean crust, formed at the Mid Atlantic Ridge, is overlain by a several kilometer thick sequence of hemipelagic sediments (Figure 2; Dash et al 1976;Courtney & White, 1986;Williams et al, 1990;Müller et al, 2008;Pim et al, 2008).…”

Section: The Cape Verde Archipelagomentioning

confidence: 98%

Magma storage at Ocean Islands: insights from Cape Verde

Barker

¹

,

Rydeblad

²

,

Silva

³

2021

Preprint

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The Cape Verde archipelago is a group of Ocean Islands in the Central Atlantic that forms two chains of islands trending Northwest and Southwest. Several of the islands are considered to be volcanically active, with frequent eruptions on Fogo. We examine the mineral chemistry and thermobarometry of the southern islands; Santiago, Fogo and Brava together with the Cadamosto Seamount. Our objective is to explore the magmatic storage system and implications for volcanic eruptions and associated hazards at Cape Verde. The volcanic rocks at Cape Verde are alkaline and dominantly mafic, whereas the island of Brava and the Cadamosto Seamount are unusually felsic. Clinopyroxene compositions range from 60 to 90 Mg# at Santiago and Fogo. In contrast, at Brava and the Cadamosto Seamount the clinopyroxene compositions are 5 to 75 Mg#. Mineral chemistry and zonation records fractional crystallization, recharge, aggregation of crystals, magma mixing and variations in thermal conditions of the magma at temperatures from 925 to 1250ºC. Magma storage depths at Santiago, Fogo, Brava and the Cadamosto Seamount are between 12 and 40 km, forming deep sub-Moho magma storage zones. Transient magma storage in the crust is suggested by fluid inclusion re-equilibration and pre-eruption seismicity. A global compilation of magma storage at Ocean Islands suggests deep magma storage is a common feature and volcanic eruptions are often associated with rapid magma ascent through the crust. Shallow magma storage is more variable and likely reflects local variations in crustal structure, sediment supply and tectonics. Petrological constraints on the magma plumbing system at Cape Verde and elsewhere are vital to integrate with deformation models and seismicity in order to improve understanding and mitigation of the volcanic hazards.

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“…Evidence for fracture zone offsets is documented by magnetic lineations and gravity anomalies (Figure 3; Hayes and Rabinowitz, 1975;Dash et al, 1976;Williams et al 1990;Verhoef et al 1991;Roest et al 1992;. Additionally brittle deformation through normal, reverse and transverse faults has formed horst and graben structures on the Cape Verde Rise (Figure 3b; Efimov & Skolotnev, 2006;Skolotnev et al, 2007;. The Cretaceous ocean crust, formed at the Mid Atlantic Ridge, is overlain by a several kilometer thick sequence of hemipelagic sediments (Figure 2; Dash et al 1976;Courtney & White, 1986;Williams et al, 1990;Müller et al, 2008;Pim et al, 2008).…”

Section: The Cape Verde Archipelagomentioning

confidence: 99%

Magma Storage at Ocean Islands

Barker

¹

,

Rydeblad

²

,

Silva

³

2021

Geophysical Monograph Series

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The Cape Verde archipelago is a group of Ocean Islands in the Central Atlantic that forms two chains of islands trending Northwest and Southwest. Several of the islands are considered to be volcanically active, with frequent eruptions on Fogo. We examine the mineral chemistry and thermobarometry of the southern islands; Santiago, Fogo and Brava together with the Cadamosto Seamount. Our objective is to explore the magmatic storage system and implications for volcanic eruptions and associated hazards at Cape Verde. The volcanic rocks at Cape Verde are alkaline and dominantly mafic, whereas the island of Brava and the Cadamosto Seamount are unusually felsic. Clinopyroxene compositions range from 60 to 90 Mg# at Santiago and Fogo. In contrast, at Brava and the Cadamosto Seamount the clinopyroxene compositions are 5 to 75 Mg#. Mineral chemistry and zonation records fractional crystallization, recharge, aggregation of crystals, magma mixing and variations in thermal conditions of the magma at temperatures from 925 to 1250ºC. Magma storage depths at Santiago, Fogo, Brava and the Cadamosto Seamount are between 12 and 40 km, forming deep sub-Moho magma storage zones. Transient magma storage in the crust is suggested by fluid inclusion re-equilibration and pre-eruption seismicity. A global compilation of magma storage at Ocean Islands suggests deep magma storage is a common feature and volcanic eruptions are often associated with rapid magma ascent through the crust. Shallow magma storage is more variable and likely reflects local variations in crustal structure, sediment supply and tectonics. Petrological constraints on the magma plumbing system at Cape Verde and elsewhere are vital to integrate with deformation models and seismicity in order to improve understanding and mitigation of the volcanic hazards.

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New data on the geological structure of the junction of the Cape Verde Rise, Cape Verde Abyssal Basin, and Bathymetrists Seamounts (Central Atlantic Ocean)

Cited by 6 publications

References 2 publications

Origin of submarine volcanism at the eastern margin of the central atlantic: Investigation of the alkaline volcanic rocks of the carter seamount (Grimaldi Seamounts)

Origin of submarine volcanism at the eastern margin of the central atlantic: Investigation of the alkaline volcanic rocks of the carter seamount (Grimaldi Seamounts)

Magma storage at Ocean Islands: insights from Cape Verde

Magma Storage at Ocean Islands

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