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Indo-Atlantic Plate Accelerations Around the Cretaceous-Paleogene Boundary: a Time-Scale Error, Not a Plume-Push Signal L
https://doi.org/10.1130/G47859.1 Manuscript received 30 April 2020 Revised manuscript received 25 June 2020 Manuscript accepted 1 July 2020 © 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 31 July 2020 Indo-Atlantic plate accelerations around the Cretaceous-Paleogene boundary: A time-scale error, not a plume-push signal L. Pérez-Díaz1*, G. Eagles2 and K. Sigloch1 1 Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN Oxford, UK 2 Alfred Wegener Institut, Am Handelshafen 12, 27570 Bremerhaven, Germany ABSTRACT 3 m.y.) evidence from the divergent IND-AFR It has been suggested that plume arrival at the base of the lithosphere introduces a push and IND-ANT plate boundaries, both recording force that overwhelms the balance of torques driving plate circuits, leading to plate-tectonic re- sharp increases in plate divergence rates at times organizations. Among the most compelling evidence in support of a “plume-push” mechanism coincident with plume arrival. They also used is the apparent coincidence between eruption of the Deccan flood basalts around 67–64 Ma lower-resolution (3–6 m.y.) models of seafloor and a short-lived increase in Indian (and decrease in African) plate speed. Using existing spreading data between Africa and Antarctica and newly calculated high-resolution plate-motion models, we show that plate divergence (AFR-ANT) and South America (AFR-SAM) rates briefly increased throughout the Indo-Atlantic circuit, contrary to the expected effects to show decelerations in the 70–45 Ma period. -
Breakup and Early Seafloor Spreading Between India and Antarctica
Geophys. J. Int. (2007) 170, 151–169 doi: 10.1111/j.1365-246X.2007.03450.x Breakup and early seafloor spreading between India and Antarctica Carmen Gaina,1 R. Dietmar Muller¨ ,2 Belinda Brown,2 Takemi Ishihara3 and Sergey Ivanov4 1Center for Geodynamics, Geological Survey of Norway, Trondheim, Norway 2Earth Byte Group, School of Geosciences, The University of Sydney, Australia 3Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology, AIST Central 7, Tsukuba, Japan 4Polar Marine Geophysical Research Expedition, St Petersburg Accepted 2007 March 21. Received 2007 March 21; in original form 2006 May 26 SUMMARY We present a tectonic interpretation of the breakup and early seafloor spreading between India and Antarctica based on improved coverage of potential field and seismic data off the east Antarctic margin between the Gunnerus Ridge and the Bruce Rise. We have identified a series of ENE trending Mesozoic magnetic anomalies from chron M9o (∼130.2 Ma) to M2o (∼124.1 Ma) in the Enderby Basin, and M9o to M4o (∼126.7 Ma) in the Princess Elizabeth Trough and Davis Sea Basin, indicating that India–Antarctica and India–Australia breakups were roughly contemporaneous. We present evidence for an abandoned spreading centre south geoscience of the Elan Bank microcontinent; the estimated timing of its extinction corresponds to the early surface expression of the Kerguelen Plume at the Southern Kerguelen Plateau around rine 120 Ma. We observe an increase in spreading rate from west to east, between chron M9 Ma and M4 (38–54 mm yr–1), along the Antarctic margin and suggest the tectono-magmatic segmentation of oceanic crust has been influenced by inherited crustal structure, the kinematics GJI of Gondwanaland breakup and the proximity to the Kerguelen hotspot. -
The "Lost Inca Plateau": Cause of Flat Subduction Beneath Peru? M.-A
Earth and Planetary Science Letters Archimer http://www.ifremer.fr/docelec/ SEP 1999; 171(3) : 335-341 Archive Institutionnelle de l’Ifremer http://dx.doi.org/10.1016/S0012-821X(99)00153-3 © 1999 Elsevier ailable on the publisher Web site The “lost Inca Plateau”: cause of flat subduction beneath Peru? M. -A. Gutschera, *, J. -L. Olivetb, D. Aslanianb, J. -P. Eissenc and R. Mauryd a Laboratorie de Géophysique et Tectonique, Université Montpellier II, France b IFREMER, Brest, France c IRD, Brest, France d Université de Bretagne Occidentale, Brest, France *: Corresponding author : IRD Centre de Bretagne (ex ORSTOM), B.P. 70, 29280 Plouzane, France. Tel.: +33 blisher-authenticated version is av 298 22 46 68; Fax: +33 298 224514, E-mail: [email protected] Abstract: Since flat subduction of the Nazca Plate beneath Peru was first recognized in the 1970s and 1980s a satisfactory explanation has eluded researchers. We present evidence that a lost oceanic plateau (Inca Plateau) has subducted beneath northern Peru and propose that the combined buoyancy of Inca Plateau and Nazca Ridge in southern Peru supports a 1500 km long segment of the downgoing slab and shuts off arc volcanism. This conclusion is based on an analysis of the seismicity of the subducting Nazca Plate, the structure and geochemistry of the Marquesas Plateau as well as tectonic reconstructions of the Pacific–Farallon spreading center 34 to 43 Ma. These restore three sub–parallel Pacific oceanic plateaus; the Austral, Tuamotu and Marquesas, to two Farallon Plate counterparts; the Iquique and Nazca Ridges. Inca Plateau is apparently the sixth and missing piece in an ensemble of ‘V-shaped' hotspot tracks formed at on-axis positions. -
Seismic Evidence for Bottom Current Activity at the Agulhas Ridge
Global and Planetary Change 34 (2002) 185–198 www.elsevier.com/locate/gloplacha Seismic evidence for bottom current activity at the Agulhas Ridge Etienne Wildeboer Schut *, Gabriele Uenzelmann-Neben, Rainer Gersonde Alfred-Wegener-Institut fu¨r Polar-und Meeresforschung, Bremerhaven, Germany Received 12 August 2000; accepted 11 April 2001 Abstract In the South Atlantic water masses from the Atlantic and Indian Oceans meet Antarctic water masses. The Agulhas Ridge, a pronounced elevation of the ocean bottom in the eastern South Atlantic, has acted as a barrier for deep oceanic currents since the Cretaceous, such as the North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW), or water masses derived from AABW such as Circumpolar Deep Water (CDW). The history of these currents is recorded in the sedimentary sequence in the adjacent Cape and Agulhas Basins. Seismic profiles over the Agulhas Ridge show sediment packages in the Cape Basin which are interpreted as contourite sheets. These consist of thick sequences interrupted by widespread hiatuses, with a predominantly low seismic reflectivity. The seismic data shows prominent reflectors inside contourite drift bodies which, at the location of the drill-sites of Ocean Drilling Program (ODP) Leg 177, can be attributed to hiatuses in the Early Oligocene, the Middle Miocene, around the Miocene/Pliocene boundary and in the early Pleistocene. In this way, ODP Leg 177 cores were used to date an elongate contourite drift in the Cape Basin. This drift shows sediments deposited by a westward current, implying that the bottom current in the Oligocene followed the same trajectory as present-day CDW does. -
Joint Geological Survey/University of Cape Town MARINE GEOSCIENCE UNIT TECHNICAL ^REPORT NO. 13 PROGRESS REPORTS for the YEARS 1
Joint Geological Survey/University of Cape Town MARINE GEOSCIENCE UNIT TECHNICAL ^REPORT NO. 13 PROGRESS REPORTS FOR THE YEARS 1981-1982 Marine Geoscience Group Department of Geology University of Cape Town December 1982 NGU-Tfc—Kh JOINT GEOLOGICAL SURVEY/UNIVERSITY OF CAPE TOWN MARINE GEOSCIENCE UNIT TECHNICAL REPORT NO. 13 PROGRESS REPORTS FOR THE YEARS 1981-1982 Marine Geoscience Group Department of Geology University of Cape Town December 1982 The Joint Geological Survey/University of Cape Town Marine Geoscience Unit is jointly funded by the two parent organizations to promote marine geoscientific activity in South Africa. The Geological Survey Director, Mr L.N.J. Engelbrecht, and the University Research Committee are thanked for their continued generous financial and technical support for this work. The Unit was established in 1975 by the amalgamation of the Marine Geology Programme (funded by SANCOR until 1972) and the Marine Geophysical Unit. Financial ?nd technical assistance from the South African National Committee for Oceanographic Research, and the National Research Institute for Oceanology (Stellenbosch) are also gratefully acknowledged. It is the policy of the Geological Survey and the University of Cape Town that the data obtained may be presented in the form of theses for higher degrees and that completed projects shall be published without delay in appropriate media. The data and conclusions contained in this report are made available for the information of the international scientific community with tl~e request that they be not published in any manner without written permission. CONTENTS Page INTRODUCTION by R.V.Dingle i PRELIMINARY REPORT ON THE BATHYMETRY OF PART OF 1 THE TRANSKEI BASIN by S.H. -
Connecting the Deep Earth and the Atmosphere
In Mantle Convection and Surface Expression (Cottaar, S. et al., eds.) AGU Monograph 2020 (in press) Connecting the Deep Earth and the Atmosphere Trond H. Torsvik1,2, Henrik H. Svensen1, Bernhard Steinberger3,1, Dana L. Royer4, Dougal A. Jerram1,5,6, Morgan T. Jones1 & Mathew Domeier1 1Centre for Earth Evolution and Dynamics (CEED), University of Oslo, 0315 Oslo, Norway; 2School of Geosciences, University of Witwatersrand, Johannesburg 2050, South Africa; 3Helmholtz Centre Potsdam, GFZ, Telegrafenberg, 14473 Potsdam, Germany; 4Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459, USA; 5DougalEARTH Ltd.1, Solihull, UK; 6Visiting Fellow, Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. Abstract Most hotspots, kimberlites, and large igneous provinces (LIPs) are sourced by plumes that rise from the margins of two large low shear-wave velocity provinces in the lowermost mantle. These thermochemical provinces have likely been quasi-stable for hundreds of millions, perhaps billions of years, and plume heads rise through the mantle in about 30 Myr or less. LIPs provide a direct link between the deep Earth and the atmosphere but environmental consequences depend on both their volumes and the composition of the crustal rocks they are emplaced through. LIP activity can alter the plate tectonic setting by creating and modifying plate boundaries and hence changing the paleogeography and its long-term forcing on climate. Extensive blankets of LIP-lava on the Earth’s surface can also enhance silicate weathering and potentially lead to CO2 drawdown (cooling), but we find no clear relationship between LIPs and post-emplacement variation in atmospheric CO2 proxies on very long (>10 Myrs) time- scales. -
The Kerguelen Plume: What We Have Learned from ~120 Myr of Volcanism
The Kerguelen Plume: What We Have Learned From ~120 Myr of Volcanism F.A. Frey (1) and D. Weis (2) (1) Earth Atmospheric & Planetary Sciences, MIT, Cambridge, MA 02139, (2) EOS, University of British Columbia, Vancouver, BC V6T1Z4 The Kerguelen Plume has had a major role in creating major volcanic features in the Eastern Indian Ocean over the last ~120 myr. In order to understand this role, igneous basement has been drilled and cored at 9 sites on the Kerguelen Plateau, 2 sites on Broken Ridge and 7 sites on the Ninetyeast Ridge(1,2,3,4). In addition, stratigraphic volcanic sections on the two relatively young islands (Kerguelen and Heard) constructed on the Kerguelen Plateau have been studied(5,6), as well as dredged samples from seamounts defining a linear trend between these islands(7). Major results are: (a) The Kerguelen Plateau began forming at ~120 Ma, after Gondwana breakup. Eruption ages decrease from ~120 Ma in the southern plateau to ~95 Ma in the central plateau. This age range is not consistent with a pulse of volcanism associated with melting of a single, large plume head. (b) The sampled volcanic portion of the plateau is dominantly tholeiitic basalt that formed islands, but the waning stage of volcanism included alkalic basalt and highly evolved, explosively erupted trachytes and rhyolites. (c) At several geographically dispersed locations on the plateau, the Cretaceous tholeiitic basalt has been contaminated by a component derived from continental crust. Geophysical data are consistent with continental crust in the oceanic lithosphere and clasts of ancient garnet-biotite gneiss occur in a conglomerate intercalated with basalt on Elan Bank. -
Gondwana Breakup Via Double-Saloon-Door Rifting and Seafloor Spreading in a Backarc Basin During Subduction Rollback
Available online at www.sciencedirect.com Tectonophysics 445 (2007) 245–272 www.elsevier.com/locate/tecto Gondwana breakup via double-saloon-door rifting and seafloor spreading in a backarc basin during subduction rollback A.K. Martin Repsol YPF Exploración, Al Fattan Plaza, PO Box 35700, Dubai, United Arab Emirates Received 2 February 2007; received in revised form 4 July 2007; accepted 21 August 2007 Available online 28 August 2007 Abstract A model has been developed where two arc-parallel rifts propagate in opposite directions from an initial central location during backarc seafloor spreading and subduction rollback. The resultant geometry causes pairs of terranes to simultaneously rotate clockwise and counterclockwise like the motion of double-saloon-doors about their hinges. As movement proceeds and the two terranes rotate, a gap begins to extend between them, where a third rift initiates and propagates in the opposite direction to subduction rollback. Observations from the Oligocene to Recent Western Mediterranean, the Miocene to Recent Carpathians, the Miocene to Recent Aegean and the Oligocene to Recent Caribbean point to a two-stage process. Initially, pairs of terranes comprising a pre-existing retro-arc fold thrust belt and magmatic arc rotate about poles and accrete to adjacent continents. Terrane docking reduces the width of the subduction zone, leading to a second phase during which subduction to strike-slip transitions initiate. The clockwise rotated terrane is caught up in a dextral strike-slip zone, whereas the counterclockwise rotated terrane is entrained in a sinistral strike-slip fault system. The likely driving force is a pair of rotational torques caused by slab sinking and rollback of a curved subduction hingeline. -
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. -
JOIDES Resolution Expedition 361 (Southern African Climates) Site
IODP Expedition 361: Southern African Climates Site U1475 Summary Background and Objectives Site U1475 is located on the southwestern flank of Agulhas Plateau (41°25.61′S, 25°15.64′E), ~450 nmi south of Port Elizabeth, South Africa, in a water depth of 2669 mbsl. The Agulhas Plateau, which was formed during the early stages of the opening of the South Atlantic about 90 Ma (Parsiegla et al., 2008), is a major bathymetric high that is variably coated with sediments (Uenzelmann Neben, 2001). The 230,000 km2 plateau, which ascends up to ~2500 m above the adjacent seafloor, is bounded on the north by the 4700 m deep Agulhas Passage and is flanked by the Agulhas Basin in the west and the Transkei Basin in the northeast. The northern part of the plateau is characterized by rugged topography, while the central and southern part of the plateau exhibits a relatively smooth topography (Allen and Tucholke, 1981) and has greater sediment thickness (Uenzelmann Neben, 2001). A strong water mass transport flows across the Agulhas Plateau region (Macdonald, 1993), which involves the water column from the surface down to Upper Circumpolar Deep Water. The hydrography of the upper ocean is dominated by the Agulhas Return Current, which comprises the component of the Agulhas Current that is not leaked to the South Atlantic Ocean but rather flows eastwards from the retroflection (Lutjeharms and Ansorge, 2001). Antarctic Intermediate Water, below the Agulhas Return Current, also follows the same flow path near South Africa as the Agulhas Current showing a similar retroflection (Lutjeharms, 1996). -
Thermal Development and Rejuvenation of the Marginal Plateaus Along the Transtensional Volcanic Margins of the Norwegian- Greenland Sea
City University of New York (CUNY) CUNY Academic Works All Dissertations, Theses, and Capstone Projects Dissertations, Theses, and Capstone Projects 1995 Thermal Development and Rejuvenation of the Marginal Plateaus Along the Transtensional Volcanic Margins of the Norwegian- Greenland Sea Nilgun Okay The Graduate Center, City University of New York How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_etds/3901 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. -
The Shatsky Rise Oceanic Plateau Structure from Two-Dimensional Multichannel Seismic Refl Ection Profi Les and Implications for Oceanic Plateau Formation
Downloaded from specialpapers.gsapubs.org on June 2, 2015 The Geological Society of America Special Paper 511 2015 The Shatsky Rise oceanic plateau structure from two-dimensional multichannel seismic refl ection profi les and implications for oceanic plateau formation Jinchang Zhang* William W. Sager† Department of Oceanography, Texas A&M University, College Station, Texas 77843, USA Jun Korenaga Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA ABSTRACT The Shatsky Rise is one of the largest oceanic plateaus, a class of volcanic fea- tures whose formation is poorly understood. It is also a plateau that was formed near spreading ridges, but the connection between the two features is unclear. The geologic structure of the Shatsky Rise can help us understand its formation. Deeply penetrating two-dimensional (2-D) multichannel seismic (MCS) refl ection profi les were acquired over the southern half of the Shatsky Rise, and these data allow us to image its upper crustal structure with unprecedented detail. Synthetic seismo- grams constructed from core and log data from scientifi c drilling sites crossed by the MCS lines establish the seismic response to the geology. High-amplitude basement refl ections result from the transition between sediment and underlying igneous rock. Intrabasement refl ections are caused by alternations of lava fl ow packages with dif- fering properties and by thick interfl ow sediment layers. MCS profi les show that two of the volcanic massifs within the Shatsky Rise are immense central volcanoes. The Tamu Massif, the largest (~450 km × 650 km) and oldest (ca. 145 Ma) volcano, is a single central volcano with a rounded shape and shallow fl ank slopes (<0.5°–1.5°), characterized by lava fl ows emanating from the volcano center and extending hun- dreds of kilometers down smooth, shallow fl anks to the surrounding seafl oor.