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Iceland Is Cool: an Origin for the Iceland Volcanic Province in the Remelting of Subducted Iapetus Slabs at Normal Mantle Temperatures
Iceland is cool: An origin for the Iceland volcanic province in the remelting of subducted Iapetus slabs at normal mantle temperatures G. R. Foulger§1 & Don L. Anderson¶ §Department of Geological Sciences, University of Durham, Science Laboratories, South Rd., Durham, DH1 3LE, U.K. ¶California Institute of Technology, Seismological Laboratory, MC 252-21, Pasadena, CA 91125, U. S. A. Abstract The time-progressive volcanic track, high temperatures, and lower-mantle seismic anomaly predicted by the plume hypothesis are not observed in the Iceland region. A model that fits the observations better attributes the enhanced magmatism there to the extraction of melt from a region of upper mantle that is at relatively normal temperature but more fertile than average. The source of this fertility is subducted Iapetus oceanic crust trapped in the Caledonian suture where it is crossed by the mid-Atlantic ridge. The extraction of enhanced volumes of melt at this locality on the spreading ridge has built a zone of unusually thick crust that traverses the whole north Atlantic. Trace amounts of partial melt throughout the upper mantle are a consequence of the more fusible petrology and can explain the seismic anomaly beneath Iceland and the north Atlantic without the need to appeal to very high temperatures. The Iceland region has persistently been characterised by complex jigsaw tectonics involving migrating spreading ridges, microplates, oblique spreading and local variations in the spreading direction. This may result from residual structural complexities in the region, inherited from the Caledonian suture, coupled with the influence of the very thick crust that must rift in order to accommodate spreading-ridge extension. -
51. Breakup and Seafloor Spreading Between the Kerguelen Plateau-Labuan Basin and the Broken Ridge-Diamantina Zone1
Wise, S. W., Jr., Schlich, R., et al., 1992 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 120 51. BREAKUP AND SEAFLOOR SPREADING BETWEEN THE KERGUELEN PLATEAU-LABUAN BASIN AND THE BROKEN RIDGE-DIAMANTINA ZONE1 Marc Munschy,2 Jerome Dyment,2 Marie Odile Boulanger,2 Daniel Boulanger,2 Jean Daniel Tissot,2 Roland Schlich,2 Yair Rotstein,2,3 and Millard F. Coffin4 ABSTRACT Using all available geophysical data and an interactive graphic software, we determined the structural scheme of the Australian-Antarctic and South Australian basins between the Kerguelen Plateau and Broken Ridge. Four JOIDES Resolution transit lines between Australia and the Kerguelen Plateau were used to study the detailed pattern of seafloor spreading at the Southeast Indian Ridge and the breakup history between the Kerguelen Plateau and Broken Ridge. The development of rifting between the Kerguelen Plateau-Labuan Basin and the Broken Ridge-Diamantina Zone, and the evolution of the Southeast Indian Ridge can be summarized as follows: 1. From 96 to 46 Ma, slow spreading occurred between Antarctica and Australia; the Kerguelen Plateau, Labuan Basin, and Diamantina Zone stretched at 88-87 Ma and 69-66 Ma. 2. From 46 to 43 Ma, the breakup between the Southern Kerguelen Plateau and the Diamantina Zone propagated westward at a velocity of about 300 km/m.y. The breakup between the Northern Kerguelen Plateau and Broken Ridge occurred between 43.8 and 42.9 Ma. 3. After 43 Ma, volcanic activity developed on the Northern Kerguelen Plateau and at the southern end of the Ninetyeast Ridge. Lava flows obscured the boundaries of the Northern Kerguelen Plateau north of 48°S and of the Ninetyeast Ridge south of 32°S, covering part of the newly created oceanic crust. -
Hawaiian Volcanoes: from Source to Surface Site Waikolao, Hawaii 20 - 24 August 2012
AGU Chapman Conference on Hawaiian Volcanoes: From Source to Surface Site Waikolao, Hawaii 20 - 24 August 2012 Conveners Michael Poland, USGS – Hawaiian Volcano Observatory, USA Paul Okubo, USGS – Hawaiian Volcano Observatory, USA Ken Hon, University of Hawai'i at Hilo, USA Program Committee Rebecca Carey, University of California, Berkeley, USA Simon Carn, Michigan Technological University, USA Valerie Cayol, Obs. de Physique du Globe de Clermont-Ferrand Helge Gonnermann, Rice University, USA Scott Rowland, SOEST, University of Hawai'i at M noa, USA Financial Support 2 AGU Chapman Conference on Hawaiian Volcanoes: From Source to Surface Site Meeting At A Glance Sunday, 19 August 2012 1600h – 1700h Welcome Reception 1700h – 1800h Introduction and Highlights of Kilauea’s Recent Eruption Activity Monday, 20 August 2012 0830h – 0900h Welcome and Logistics 0900h – 0945h Introduction – Hawaiian Volcano Observatory: Its First 100 Years of Advancing Volcanism 0945h – 1215h Magma Origin and Ascent I 1030h – 1045h Coffee Break 1215h – 1330h Lunch on Your Own 1330h – 1430h Magma Origin and Ascent II 1430h – 1445h Coffee Break 1445h – 1600h Magma Origin and Ascent Breakout Sessions I, II, III, IV, and V 1600h – 1645h Magma Origin and Ascent III 1645h – 1900h Poster Session Tuesday, 21 August 2012 0900h – 1215h Magma Storage and Island Evolution I 1215h – 1330h Lunch on Your Own 1330h – 1445h Magma Storage and Island Evolution II 1445h – 1600h Magma Storage and Island Evolution Breakout Sessions I, II, III, IV, and V 1600h – 1645h Magma Storage -
Variations in Amount and Direction of Seafloor Spreading Along the Northeast Atlantic Ocean and Resulting Deformation of The
Variations in amount and direction of seafloor spreading along the northeast Atlantic Ocean and resulting deformation of the continental margin of northwest Europe Eline Le Breton, P.R. Cobbold, Olivier Dauteuil, Gawin Lewis To cite this version: Eline Le Breton, P.R. Cobbold, Olivier Dauteuil, Gawin Lewis. Variations in amount and direction of seafloor spreading along the northeast Atlantic Ocean and resulting deformation of the continental margin of northwest Europe. Tectonics, American Geophysical Union (AGU), 2012, 31, pp.TC5006. 10.1029/2011TC003087. insu-00756536 HAL Id: insu-00756536 https://hal-insu.archives-ouvertes.fr/insu-00756536 Submitted on 26 Nov 2012 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. TECTONICS, VOL. 31, TC5006, doi:10.1029/2011TC003087, 2012 Variations in amount and direction of seafloor spreading along the northeast Atlantic Ocean and resulting deformation of the continental margin of northwest Europe E. Le Breton,1,2 P. R. Cobbold,1 O. Dauteuil,1 and G. Lewis3 Received 22 December 2011; revised 16 August 2012; accepted 31 August 2012; published 16 October 2012. [1] The NE Atlantic Ocean opened progressively between Greenland and NW Europe during the Cenozoic. -
Wilson Cycle Tectonics: East Greenland-Norway Closure and Opening Trond H. Torsvik (University of Oslo) It Was Not Until Wilson
Wilson Cycle Tectonics: East Greenland-Norway closure and opening Trond H. Torsvik (University of Oslo) It was not until Wilson’s (1966) classic paper Did the Atlantic close and then re-open? that plate tectonic processes were understood to have been operating before Pangea. Wilson’s succession of rifting, crustal subsidence and ocean opening, subduction initiation and ocean closure, and finally continent-continent collision was dubbed the ‘Wilson Cycle’ by Kevin Burke. The ‘Wilson Cycle’ concept also spurred an intensive search for older supercontinents. Baltica became isolated after the break-up of the Rodinia supercontinent and its Late Precambrian separation from Laurentia (Greenland) through the opening of the Iapetus Ocean, and continued so until the latest Ordovician and Silurian, when Baltica first collided with Avalonia and then more forcefully with Laurentia to shape Laurussia during the Scandian part of the Caledonide Orogeny. The Scandian orogenic event was marked by oblique collision and deep subduction of Baltican crust beneath Laurentia. The Iapetus Suture ran through the UK, probably beneath the transition between the platform/inner parts of the Vøring Basin, and continued into the Barents Sea Region and then into the High Arctic. Since the Late Palaeozoic, and directly linked to the break-up of Pangea, the Norwegian continental shelf experienced multi-phase rifting, culminating in the separation of Greenland and Norway and the formation of the Northeast Atlantic Ocean in the Early Tertiary. Continental break-up may be guided by pre-existing rheological heterogeneities due to repeated weakening of continental margins through previous ‘Wilson Cycles’. In the North Atlantic realm, prolonged post-Caledonian extension and sedimentary basin formation exploited lithospheric heterogeneities inherited from a previous ‘Wilson Cycle’, but Early Eocene break-up chose locations and directions unrelated to the previous evolution. -
Insights on the Indian Ocean Tectonics and Geophysics Supported by GMT Polina Lemenkova
Insights on the Indian Ocean tectonics and geophysics supported by GMT Polina Lemenkova To cite this version: Polina Lemenkova. Insights on the Indian Ocean tectonics and geophysics supported by GMT. Riscuri si Catastrofe, ”Babes-Bolyai” University from Cluj-Napoca, Faculty of Geography, 2020, 27 (2), pp.67- 83. 10.24193/RCJ2020_12. hal-03033533 HAL Id: hal-03033533 https://hal.archives-ouvertes.fr/hal-03033533 Submitted on 1 Dec 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License Riscuri și catastrofe, an XX, vol, 27 nr. 2/2020 INSIGHTS ON THE INDIAN OCEAN TECTONICS AND GEOPHYSICS SUPPORTED BY GMT POLINA LEMENKOVA1 Abstract. Insights on the Indian Ocean Tectonics and Geophysics Supported by GMT. This paper presented analyzed and summarized data on geological and geophysical settings about the tectonics and geological structure of the seafloor of the Indian Ocean by thematic visualization of the topographic, geophysical and geo- logical data. The seafloor topography of the Indian Ocean is very complex which includes underwater hills, isolated mountains, underwater canyons, abyssal and ac- cumulative plains, trenches. Complex geological settings explain seismic activity, repetitive earthquakes, and tsunami. -
Continental Crust Beneath Southeast Iceland
Continental crust beneath southeast Iceland Trond H. Torsvika,b,c,1, Hans E. F. Amundsend, Reidar G. Trønnesa,e, Pavel V. Doubrovinea, Carmen Gainaa, Nick J. Kusznirf, Bernhard Steinbergera,g, Fernando Corfua,h, Lewis D. Ashwalc, William L. Griffini, Stephanie C. Wernera, and Bjørn Jamtveitj aCentre for Earth Evolution and Dynamics, University of Oslo, N-0315 Oslo, Norway; bGeological Survey of Norway, Geodynamics, N-7491 Trondheim, Norway; cSchool of Geosciences, University of Witwatersrand, Wits 2050, South Africa; dVestfonna Geophysical, N-8310 Kabelvåg, Norway; eNatural History Museum, University of Oslo, N-0318 Oslo, Norway, fDepartment of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 3GP, United Kingdom; gHelmholtz Centre Potsdam, GeoForschungsZentrum, Section 2.5 Geodynamic Modelling, D-14473 Potsdam, Germany; hGeosciences, University of Oslo, N-0316 Oslo, Norway; iCore to Crust Fluid Systems/Geochemical Evolution and Metallogeny of Continents, Macquarie University, Sydney, NSW 2109, Australia; and jPhysics of Geological Processes, University of Oslo, N-0316 Oslo, Norway Edited by Norman H. Sleep, Stanford University, Stanford, CA, and approved March 11, 2015 (received for review December 4, 2014) Themagmaticactivity(0–16 Ma) in Iceland is linked to a deep mantle lites, is characterized by high 87Sr/86Sr, intermediate 206Pb/204Pb, plume that has been active for the past 62 My. Icelandic and north- as well as 207Pb/204Pb and 208Pb/204Pb ratios that lie well above east Atlantic basalts contain variable proportions of two enriched the Northern Hemisphere Reference Line (12) (Figs. 3 and 4). components, interpreted as recycled oceanic crust supplied by the These geochemical features, which also include uniformly high 18 plume, and subcontinental lithospheric mantle derived from the δ Obulk-rock of 4.8–5.9‰, have been attributed to an enriched- nearby continental margins. -
Seafloor Hydrothermal Activity Around a Large Non-Transform
Journal of Marine Science and Engineering Article Seafloor Hydrothermal Activity around a Large Non-Transform Discontinuity along Ultraslow-Spreading Southwest Indian Ridge (48.1–48.7◦ E) Dong Chen 1,2, Chunhui Tao 2,3,*, Yuan Wang 2, Sheng Chen 4, Jin Liang 2, Shili Liao 2 and Teng Ding 1 1 Institute of Marine Geology, College of Oceanography, Hohai University, Nanjing 210098, China; [email protected] (D.C.); [email protected] (T.D.) 2 Key Laboratory of Submarine Geosciences, SOA & Second Institute of Oceanography, MNR, Hangzhou 310012, China; [email protected] (Y.W.); [email protected] (J.L.); [email protected] (S.L.) 3 School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China 4 Ocean Technology and Equipment Research Center, School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; [email protected] * Correspondence: [email protected] Abstract: Non-transform discontinuity (NTD) is one category of tectonic units along slow- and ultraslow-spreading ridges. Some NTD-related hydrothermal fields that may reflect different driving mechanisms have been documented along slow-spreading ridges, but the discrete survey strategy makes it hard to evaluate the incidence of hydrothermal activity. On ultraslow-spreading ridges, fewer NTD-related hydrothermal activities were reported. Factors contributing to the occurrence of hydrothermal activities at NTDs and whether they could be potential targets for hydrothermal explo- Citation: Chen, D.; Tao, C.; Wang, Y.; Chen, S.; Liang, J.; Liao, S.; Ding, T. ration are poorly known. Combining turbidity and oxidation reduction potential (ORP) sensors with Seafloor Hydrothermal Activity a near-bottom camera, Chinese Dayang cruises from 2014 to 2018 have conducted systematic towed around a Large Non-Transform surveys for hydrothermal activity around a large NTD along the ultraslow-spreading Southwest ◦ Discontinuity along Indian Ridge (SWIR, 48.1–48.7 E). -
Geophysical Journal International
Geophysical Journal International Geophys. J. Int. (2013) doi: 10.1093/gji/ggt372 Geophysical Journal International Advance Access published October 11, 2013 Cretaceous to present kinematics of the Indian, African and Seychelles plates Graeme Eagles∗ and Ha H. Hoang Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, United Kingdom. E-mail: [email protected] Downloaded from Accepted 2013 September 16. Received 2013 September 13; in original form 2012 November 12 SUMMARY An iterative inverse model of seafloor spreading data from the Mascarene and Madagascar http://gji.oxfordjournals.org/ basins and the flanks of the Carlsberg Ridge describes a continuous history of Indian–African Plate divergence since 84 Ma. Visual-fit modelling of conjugate magnetic anomaly data from near the Seychelles platform and Laxmi Ridge documents rapid rotation of a Seychelles Plate about a nearby Euler pole in Palaeocene times. As the Euler pole migrated during this rotation, the Amirante Trench on the western side of the plate accommodated first convergence and later divergence with the African Plate. The unusual present-day morphology of the Amirante GJI Geodynamics and tectonics Trench and neighbouring Amirante Banks can be related to crustal thickening by thrusting and at Alfred Wegener Institut fuer Polar- und Meeresforschung Bibliothek on October 11, 2013 folding during the convergent phase and the subsequent development of a spreading centre with a median valley during the divergent phase. The model fits FZ trends in the north Arabian and east Somali basins, suggesting that they formed in India–Africa Plate divergence. Seafloor fabric in and between the basins shows that they initially hosted a segmented spreading ridge that accommodated slow plate divergence until 71–69 Ma, and that upon arrival of the Deccan–Reunion´ plume and an increase to faster plate divergence rates in the period 69–65 Ma, segments of the ridge lengthened and propagated. -
21. Tectonic Evolution of the Atlantis Ii Fracture Zone1
Von Herzen, R.P., Robinson, P.T., et al., 1991 Proceedings of the Ocean Drilling Program, Scientific Results,Vol. 118 21. TECTONIC EVOLUTION OF THE ATLANTIS II FRACTURE ZONE1 Henry J.B. Dick,2 Hans Schouten,2 Peter S. Meyer,2 David G. Gallo,2 Hugh Bergh,3 Robert Tyce,4 Phillipe Patriat,5 Kevin T.M. Johnson,2 Jon Snow,2 and Andrew Fisher6 ABSTRACT SeaBeam echo sounding, seismic reflection, magnetics, and gravity profiles were run along closely spaced tracks (5 km) parallel to the Atlantis II Fracture Zone on the Southwest Indian Ridge, giving 80% bathymetric coverage of a 30- × 170-nmi strip centered over the fracture zone. The southern and northern rift valleys of the ridge were clearly defined and offset north-south by 199 km. The rift valleys are typical of those found elsewhere on the Southwest Indian Ridge, with relief of more than 2200 m and widths from 22 to 38 km. The ridge-transform intersections are marked by deep nodal basins lying on the transform side of the neovolcanic zone that defines the present-day spreading axis. The walls of the transform generally are steep (25°-40°), although locally, they can be more subdued. The deepest point in the transform is 6480 m in the southern nodal basin, and the shallowest is an uplifted wave-cut terrace that exposes plutonic rocks from the deepest layer of the ocean crust at 700 m. The transform valley is bisected by a 1.5-km-high median tectonic ridge that extends from the northern ridge-transform intersection to the midpoint of the active transform. -
CHAPTER 2 Aseismic Ridges of the Northeastern Indian Ocean
CHAPTER 2 Aseismic ridges of the northeastern Indian Ocean 2.1 Evolution of the Indian Ocean 2.2 Major Aseismic Ridges 2.2.1 The Ninetyeast Ridge 2.2.2 The Chagos-Laccadive Ridge 2.2.3 The 85°E Ridge 2.2.4 The Comorin Ridge 2.2.5 The Broken Ridge 2.3 Other Major Structural Features 2.3.1 The Kerguelen Plateau 2.3.2 The Elan Bank 2.3.3 The Afanasy Nikitin seamount Chapter 2 Aseismic ridges of the northeastern Indian Ocean 2.1 Evolution of the Indian Ocean The initiation of the Indian Ocean commenced with the breakup of the Gondwanaland super-continent into two groups of continental masses during the Mesozoic period (Norton and Sclater, 1979). The first split of the Gondwanaland may possibly have associated with the Karoo mega-plume (Lawver and Gahagan, 1998). Followed by this rifting phase, during the late Jurassic, the Mozambique and Somali basins have formed by seafloor spreading activity of series of east-west trending ridge segments. Thus, the Gondwanaland super-continent divided into western and eastern continental blocks. The Western Gondwanaland consisted of Africa, Arabia and South America, whereas the East Gondwanaland consisted of Antarctica, Australia, New Zeeland, Seychelles, Madagascar and India-Sri Lanka (Figure 2.1). After initial break-up, the East Gondwanaland moved southwards from the West Gondwanaland and led to gradual enlargement of the intervening seaways between them (Bhattacharya and Chaubey, 2001). Both West and East Gondwanaland masses have further sub-divided during the Cretaceous period. Approximate reconstructions of continental masses of the Gondwanaland from Jurassic to Present illustrating the aforesaid rifting events are shown in Figure 2.1 (Royer et al., 1992). -
The Indian Ocean Diverse Ecosystems Harbor Distinctive Deep-Sea Life and Sought-After Minerals
A fact sheet from April 2018 IFM-GEOMAR The Indian Ocean Diverse ecosystems harbor distinctive deep-sea life and sought-after minerals Overview Vast abyssal plains, mountain chains, and seamounts cover the bottom of the Indian Ocean. Each area is home to life forms suited to its particularities—and each also holds valuable minerals that could be removed through seabed mining. Hydrothermal vents spew superheated, mineral-laden water into their surroundings that, when cooled, forms towers containing copper, cobalt, nickel, zinc, gold, and rare earth elements. These minerals are essential to modern economies. The vent zones are biologically rich as well, supporting mussels, stalked barnacles, scaly-foot snails, and a variety of microbes with potential biomedical and industrial applications. Atop the Indian Ocean’s abyssal plains are more than a billion potato-size nodules with rich concentrations of manganese, copper, cobalt, and nickel. On and near the nodules, wildlife—such as sponges, sea cucumbers, and fish—has evolved to flourish in the deep cold and darkness. Seabed mining is expected to have a significant and long-lasting impact on these deep-sea ecosystems. Mining equipment would remove or degrade habitats, sediment plumes could smother nearby life, and noise and light could harm the unique species that have evolved in order to live here. The International Seabed Authority (ISA) was established by the Law of the Sea treaty to manage seabed mining in areas beyond national jurisdiction while protecting the marine environment. The ISA is drafting regulations to accomplish these objectives with rules on where and how seabed mining could occur.