Mantle Dynamics and Characteristics of the Azores Plateau
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S41598-020-76691-1 1 Vol.:(0123456789)
www.nature.com/scientificreports OPEN Rifting of the oceanic Azores Plateau with episodic volcanic activity B. Storch1*, K. M. Haase1, R. H. W. Romer1, C. Beier1,2 & A. A. P. Koppers3 Extension of the Azores Plateau along the Terceira Rift exposes a lava sequence on the steep northern fank of the Hirondelle Basin. Unlike typical tholeiitic basalts of oceanic plateaus, the 1.2 km vertical submarine stratigraphic profle reveals two successive compositionally distinct basanitic to alkali basaltic eruptive units. The lower unit is volumetrically more extensive with ~ 1060 m of the crustal profle forming between ~ 2.02 and ~ 1.66 Ma, followed by a second unit erupting the uppermost ~ 30 m of lavas in ~ 100 kyrs. The age of ~ 1.56 Ma of the youngest in-situ sample at the top of the profle implies that the 35 km-wide Hirondelle Basin opened after this time along normal faults. This rifting phase was followed by alkaline volcanism at D. João de Castro seamount in the basin center indicating episodic volcanic activity along the Terceira Rift. The mantle source compositions of the two lava units change towards less radiogenic Nd, Hf, and Pb isotope ratios. A change to less SiO2-undersaturated magmas may indicate increasing degrees of partial melting beneath D. João de Castro seamount, possibly caused by lithospheric thinning within the past 1.5 million years. Our results suggest that rifting of oceanic lithosphere alternates between magmatically and tectonically dominated phases. Oceanic plateaus with a crustal thickness to 30 km cover large areas in the oceans and these bathymetric swells afect oceanic currents and marine life 1,2. -
Azores and Iceland
13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2369 A COMPARATIVE STUDY ON STRONG GROUND MOTION IN TWO VOLCANIC ENVIRONMENTS: AZORES AND ICELAND Carlos S. OLIVEIRA1, Ragnar SIGBJÖRNSSON2, Simon ÓLAFSSON3 SUMMARY The objective of this paper is to present the main results of a comparative study of strong ground motion on the Azores and Iceland. These islands are a super-structural part of the Mid Atlantic Ridge, which marks the boundary between the North-American Plate and the Eurasian Plate and creates a north-south oriented belt of seismic and volcanic activity. The tectonic environments are described and compared emphasising the similarities in the geological structure, including surface geology and its effects on strong ground motion. Furthermore, the seismicity of the Azores and Iceland is compared based on earthquake catalogues using statistical analysis. The strong-motion networks on the islands are described along with the strong-motion data used in the subsequent analysis. The strong-motion data are compared using statistical analysis. The main emphasis is put on attenuation of strong-motion data, characterised by root mean square acceleration and peak ground acceleration. The attenuation is also compared to some of the common attenuation relationships, used by the engineering community in Europe and America. The main findings are that there are significant similarities between the tectonic environments of the Azores and Iceland. Furthermore, the similarities found in seismicity are statistically significant. The attenuation is characterised by rapid decay with increasing distance and high acceleration in the near source area. It is found that the same ground motion estimation models can be applied on the Azores and in Iceland. -
Tectonic-Sedimentary System of the Atlantis‒Meteor Seamounts (North
ISSN 0024-4902, Lithology and Mineral Resources, 2019, Vol. 54, No. 5, pp. 374–389. © Pleiades Publishing, Inc., 2019. Russian Text © The Author(s), 2019, published in Litologiya i Poleznye Iskopaemye, 2019, No. 5. Tectonic-Sedimentary System of the Atlantis‒Meteor Seamounts (North Atlantic): Volcanism and Sedimentation in the Late Miocene‒Pliocene and Position in the Atlantic‒Arctic Rift System N. P. Chamova, *, I. E. Stukalovaa, S. Yu. Sokolova, A. A. Peivea, N. V. Gor’kovaa, A. A. Razumovskiia, M. E. Bylinskayaa, and L. A. Golovinaa aGeological Institute, Russian Academy of Sciences, Pyzhevskii per., 7, Moscow, 119017 Russia *e-mail: [email protected] Received February 19, 2019; revised February 19, 2019; accepted March 13, 2019 Abstract—The paper analyzes original data obtained on the Atlantis‒Meteor seamount system during Cruise 33 of the R/V Akademik Nikolai Strakhov in the eastern North Atlantic. This system is a volcanic rise formed on the Canary abyssal plate and represents one of the key objects for understanding the geological history of opening of the central segment of the Atlantic Ocean. Basalts, tephrites, and organogenic terrigenous lagoonal marine sediments dredged from the Atlantis, Plato, and Cruiser seamounts are considered. Petrog- raphy and compositions of the Atlantis and Cruiser basalts reflect significant differences in settings of their eruptions. Well-crystallized vesicle-free olivine basalts from the Atlantis Seamount were ejected under deep- water conditions. Glassy vesicular basalts of the Cruiser Seamount are typical of shallow subaerial eruptions. Evidence for the accumulation of tuff breccias and tuff gravelstones of the Plato Seamount in subaerial set- tings are obtained. -
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Index [Italic page numbers indicate major references] Abaco Knoll, 359 116, 304, 310, 323 Bahama Platform, 11, 329, 331, 332, Abathomphalus mayaroensis, 101 Aquia Formation, 97, 98, 124 341, 358, 360 Abbott pluton, 220 aquifers, 463, 464, 466, 468, 471, Bahama volcanic crust, 356 Abenaki Formation, 72, 74, 257, 476, 584 Bahamas basin, 3, 5, 35, 37, 39, 40, 259, 261, 369, 372, 458 Aquitaine, France, 213, 374 50 ablation, 149 Arcadia Formation, 505 Bahamas Fracture Zone, 24, 39, 40, Abyssal Plain, 445 Archaean age, 57 50, 110, 202, 349, 358, 368 Adirondack Mountains, 568 Arctic-North Atlantic rift system, 49, Bahamas Slope, 12 Afar region, Djibouti, 220, 357 50 Bahamas-Cuban Fault system, 50 Africa, 146, 229, 269, 295, 299 Ardsley, New York, 568, 577 Baja California, Mexico, 146 African continental crust, 45, 331, Argana basin, Morocco, 206 Bajocian assemblages, 20, 32 347 Argo Fan, Scotian margin, 279 Balair fault zone, 560 African Craton, 368 Argo Salt Formation, 72, 197, 200, Baltimore Canyon trough, 3, 37, 38, African margin, 45, 374 278, 366, 369, 373 40, 50, 67, 72 , 81, 101, 102, African plate, 19, 39, 44, 49 arkoses, 3 138, 139, 222, 254, 269, 360, Afro-European plate, 197 artesian aquifers, 463 366, 369, 396, 419,437 Agamenticus pluton, 220 Ashley Formation, 126 basement rocks, 74 age, 19, 208, 223 Astrerosoma, 96 carbonate deposits, 79 Agulhas Bank, 146 Atkinson Formation, 116, 117 crustal structure, 4, 5, 46 Aiken Formation, 125 Atlantic basin, 6, 9, 264 faults in, 32 Aikin, South Carolina, 515 marine physiography, 9 geologic -
98-031 Oceanus F/W 97 Final
A hotspot created the island of Iceland and its characteristic volcanic landscape. Hitting the Hotspots Hotspots are rela- tively small regions on the earth where New Studies Reveal Critical Interactions unusually hot rocks rise from deep inside Between Hotspots and Mid-Ocean Ridges the mantle layer. Jian Lin Associate Scientist, Geology & Geophysics Department he great volcanic mid-ocean ridge system hotspots may play a critical role in shaping the stretches continuously around the globe for seafloor—acting in some cases as strategically T 60,000 kilometers, nearly all of it hidden positioned supply stations that fuel the lengthy beneath the world’s oceans. In some places, how- mid-ocean ridges with magma. ever, mid-ocean ridge volcanoes are so massive that Studies of ridge-hotspot interactions received a they emerge above sea level to create some of the major boost in 1995 when the US Navy declassified most spectacular islands on our planet. Iceland, the gravity data from its Geosat satellite, which flew Azores, and the Galápagos are examples of these from 1985 to 1990. The satellite recorded in unprec- “hotspot” islands—so named because they are edented detail the height of the ocean surface. With believed to form above small regions scattered accuracy within 5 centimeters, it revealed small around the earth where unusually hot rocks rise bumps and dips created by the gravitational pull of from deep inside the mantle layer. dense underwater mountains and valleys. Research- But hotspots may not be such isolated phenom- ers often use precise gravity measurements to probe ena. Exciting advances in satellite oceanography, unseen materials below the ocean floor. -
Marine Protected Areas in the Azores – the Case
Current challenges of the Azorean Marine Protected Areas -- The Faial-Pico MPA -- Gilberto P. Carreira [email protected] Department of Biodiversity and Marine Policy Regional Directorate for Sea Affairs Regional Secretariat of the Sea, Science and Technology Government of the Azores The plan: 1. Why is marine conservation challenging in the Azores? A. Biophysical reasons; B. Great variety if marine uses; C. Institutional complexity. 2. Marine conservation in the Azores: A. International framework; B. The building of marine conservation in the Azores. 3. Implementing MPAs policy – current processes: A. Legal framework; B. Network of marine protected areas; C. Some processes currently under way. 4. Four management instruments to manage MPAs in the Azores: A. Island Natural Parks; B. Marine Park of the Azores; C. Maritime spatial planning; D. Fisheries regulations: i. Santa Maria; ii. Graciosa; iii. São Miguel; iv. The case sudy of the Faial-Pico channel. 5. Management of MPAs in the Azores - What are the DRAM current challenges for the next future? 6. So, what would be a good contribution of AQUACROSS to the implementation of a MPA policy in the Azores? 1 - Why is marine conservation challenging in the Azores? Geography • Far from the mainland; • Islands are spread over 600 km; • Population ~250.000. A small terrestrial territory, and a huge marine territory EEZ: 957 292 Km2 (55% Portugal EEZ; 16.3% EU EEZ); Average depth: ~3000m Specificities of the Azores: Great diversity of unique habitats and ecossystems A. Biophysical -
Hotspots and Mantle Plumes Pdf
Hotspots and mantle plumes pdf Continue The mantle feathers area is hot, upwelling the mantle. A hot spot develops above the train. Magma, generated by a hot spot, rises through rigid slabs of the lithosphere and produces active volcanoes on the Earth's surface. As ocean volcanoes move away from the hotspot, they cool and subside, producing old islands, atolls and seamounts. As continental volcanoes move away from the hotspot, they cool, subside and die out. Hot spots are places inside the mantle where stones melt to generate magma. The presence of a hot spot stems from abnormal volcanism (i.e. not on the plate boundary) such as Hawaiian volcanoes within the Pacific Plate. The Hawaiian hotspot has been active for at least 70 million years, producing a volcanic chain that stretches for 3,750 miles (6,000 km) across the Pacific Northwest. Hot spots also develop under continents. Yellowstone hot spot has been active for at least 15 million years, producing a chain of caldera and volcanic features along the plains of the Snake River, which stretches 400 miles (650 km) west from northwest Wyoming to the Idaho-Oregon border. Keep in mind, however, that these are just theories. No one knows the answer. The honest answer is that many people are working on it but have not yet come up with an answer. Graphics After Morgan, J., 1971, Convection feathers in the lower mantle: Nature, art 230, p. 42-43. Volcanic regions, which are thought to feed on the underlying mantle, are abnormally hot compared to the surrounding mantle Diagram, showing a cross-section across the Earth's lithosphere (yellow) with magma rising from the mantle (red). -
Northward Drift of the Azores Plume in the Earth’S Mantle
ARTICLE https://doi.org/10.1038/s41467-019-11127-7 OPEN Northward drift of the Azores plume in the Earth’s mantle Maëlis Arnould 1,2,3, Jérôme Ganne4, Nicolas Coltice1 & Xiaojun Feng 5 Mantle plume fixity has long been a cornerstone assumption to reconstruct past tectonic plate motions. However, precise geochronological and paleomagnetic data along Pacific continuous hotspot tracks have revealed substantial drift of the Hawaiian plume. The 1234567890():,; question remains for evidence of drift for other mantle plumes. Here, we use plume-derived basalts from the Mid-Atlantic ridge to confirm that the upper-mantle thermal anomaly associated with the Azores plume is asymmetric, spreading over ~2,000 km southwards and ~600 km northwards. Using for the first time a 3D-spherical mantle convection where plumes, ridges and plates interact in a fully dynamic way, we suggest that the extent, shape and asymmetry of this anomaly is a consequence of the Azores plume moving northwards by 1–2 cm/yr during the past 85 Ma, independently from other Atlantic plumes. Our findings suggest redefining the Azores hotspot track and open the way for identifying how plumes drift within the mantle. 1 Laboratoire de Géologie, École Normale Supérieure, CNRS UMR 8538, PSL Research University, 75005 Paris, France. 2 Laboratoire de Géologie de Lyon, Terre, Planètes, Environnement, École Normale Supérieure de Lyon, Université de Lyon, Université Claude Bernard, CNRS UMR 5276, 2 rue Raphaël Dubois, 69622 Villeurbanne, France. 3 EarthByte Group, School of Geosciences, Madsen Building F09, University of Sydney, Sydney 2006 NSW, Australia. 4 IRD, CNRS, GET, Université Toulouse III, 14 Avenue Edouard Belin, 31400 Toulouse, France. -
Source Characteristics of Jurassic Ferropicrites from Dronning Maud
A106 Goldschmidt Conference Abstracts 2005 Basalt Geochemistry and Mantle Dynamics Source characteristics of Jurassic The Azores hotspot: A lower mantle ferropicrites from Dronning Maud origin for Terceira magmas as shown Land, Antarctica by Ne isotopic data 1 2 1,2 1 3 A.V. LUTTINEN AND H. HUHMA P. MADUREIRA , M. MOREIRA AND J. MATA 1Department of Geology, P.O.Box 64, FI-00014 University of 1Institut de Physique du globe de Paris, Université paris VII, Helsinki, Finland ([email protected]) CNRS UMR 7579, 4 place Jussieu, 75005 Paris, France 2Geological Survey of Finland, P.O.Box 123, FI-21520 Espoo, ([email protected]) Finland ([email protected]) 2Centro de Geofísica de Évora/Departamento de Geociências da Universidade de Évora, Rua Romão Ramalho, 59, Middle Jurassic basalts of Vestfjella, western Dronning 7000-671 Évora, Portugal ([email protected]) Maud Land comprise an Antarctic extension of the Karoo 3Centro e Departamento de Geologia da Faculdade de large igneous province. In addition to intrusive equivalents of Ciências da Universidade de Lisboa, Campo Grande, the lavas, crosscutting dolerite dikes include a group of C6-4º Piso, 1749-016 Lisboa, Portugal ([email protected]) picrites with unusually high total FeO (>14 wt.%) and low Al2O3 (<10 wt.%) at given MgO (10–18 wt.%). The picrites The collection of helium isotopic data in the last twenty are probably coeval, or nearly so, with the lavas, although years has shown different signatures for MORB and OIB precise age data are lacking. Mantle-normalised incompatible basalts and this has been used as the basis for the two-layer element fingerprints indicate two subgroups of such mantle model. -
Three-Dimensional Passive £Ow and Temperature Structure Beneath Oceanic Ridge^Ridge^Ridge Triple Junctions
Earth and Planetary Science Letters 204 (2002) 115^132 www.elsevier.com/locate/epsl Three-dimensional passive £ow and temperature structure beneath oceanic ridge^ridge^ridge triple junctions Jennifer E. Georgen a;Ã, Jian Lin b a MIT^WHOI Joint Program in Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA b Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA Received 12 March 2002; received in revised form 4 September 2002; accepted 6 September 2002 Abstract This study uses numerical modeling to investigate generalized characteristics of mantle flow and thermal structure in the vicinity of ridge^ridge^ridge (RRR) triple junctions. Oceanic triple junctions present a unique opportunity to study three-dimensional (3D) mantle dynamics in a tectonic setting considerably different than where only two plates diverge. In many prominent oceanic triple junctions, including Rodrigues, Azores, and Galapagos, the slowest- spreading ridge branch intersects the near-collinear faster-spreading branches quasi-orthogonally. This study focuses on triple junctions free of influence from nearby hotspots, similar to the geometry of the Rodrigues Triple Junction. A finite element model was used to calculate the steady-state 3D velocity flow field and temperature patterns resulting from advective and conductive heat transfer. For the slowest-spreading branch, model results predict a strong component of along-axis velocity directed away from the triple junction. Both upwelling velocity and temperature are calculated to increase along the slowest-spreading ridge toward the triple junction, approaching the upwelling rate and temperature of the fastest-spreading branch. Within 200 km of the triple junction, upwelling velocity is predicted to increase more than threefold along the slowest-spreading ridge. -
Seismicity Along the Azores-Gibraltar Region and Global Plate Kinematics
Seismicity along the Azores-Gibraltar region and global plate kinematics M. Bezzeghoud, C. Adam, E. Buforn, J. F. Borges & B. Caldeira Journal of Seismology ISSN 1383-4649 Volume 18 Number 2 J Seismol (2014) 18:205-220 DOI 10.1007/s10950-013-9416-x 1 23 Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy J Seismol (2014) 18:205–220 DOI 10.1007/s10950-013-9416-x ORIGINAL ARTICLE Seismicity along the Azores-Gibraltar region and global plate kinematics M. Bezzeghoud & C. Adam & E. Buforn & J. F. Borges & B. Caldeira Received: 11 February 2013 /Accepted: 23 December 2013 /Published online: 8 January 2014 # Springer Science+Business Media Dordrecht 2014 Abstract Seismicity along the western part of the between these two independent vector sets. Eurasia–Nubia plate boundary displays very complex Quantitatively, the slip velocities display a linear, non- patterns. The average motion is transtensional in the affine correlation with the norms of the relative kinematic Azores, dextral along the Gloria transform zone and con- velocities. -
The Biodiversity of Terrestrial Arthropods in Azores Manual Versión Española
Revista IDE@ - SEA, nº 5B (30-06-2015): 1–24. ISSN 2386-7183 1 Ibero Diversidad Entomológica @ccesible www.sea-entomologia.org/IDE@ Introduction The biodiversity of terrestrial arthropods in Azores Manual Versión española The biodiversity of terrestrial arthropods in Azores Carla Rego1,2, Mário Boieiro1,2, Virgílio Vieira1,2,3 & Paulo A.V. Borges1,2 1 Azorean Biodiversity Group (GBA, CITA-A) and Platform for Enhancing Ecological Research & Sustainability (PEERS), Universidade dos Açores, Departamento de Ciências Agrárias, 9700 -042 Angra do Heroísmo, Açores, Portugal. 2 cE3c – Centre for Ecology, Evolution and Environmental Changes / Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, 9700-042 Angra do Heroísmo, Açores, Portugal. 3 Departamento de Biologia, Universidade dos Açores, 9501-801 Ponta Delgada, Açores, Portugal 1. The Azores archipelago The Azores are a volcanic archipelago located in the middle of North Atlantic Ocean. Together with the archipelagos of Madeira, Selvagens, Canary Islands and Cabo Verde, they are part of Macaronesia, the “happy islands” (Fernández-Palacios, 2010). The Azorean Islands were discovered by Portuguese naviga- tors in 1427 (Santa Maria), Flores and Corvo being the last islands to be found in 1452. However, accord- ing to old maps its existence was previously known. It is believed that the archipelago received its name from birds that were common in these islands either the Goshawk (Açor in Portuguese) or a local subspe- cies of Buzzard (Buteo buteo rothschildi) that the sailors erroneously identified as goshawks (Frutuoso, 1963). The archipelago is composed by nine main islands and some small islets. The islands are divided in three groups: the eastern group with Santa Maria, São Miguel and Formigas islets, the central group with Terceira, Graciosa, São Jorge, Pico and Faial and the western group composed by Flores and Corvo (Fig.