DOCSLIB.ORG

Plate Convergence, Transcurrent Faults, and Internal Deformation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Plate Convergence, Transcurrent Faults, and Internal Deformation VOL. 77, NO. 23 JOURNAL OF GEOPHYSICAL RESEARCH AUGUST 10, 1972 Plate Convergence,Transcurrent Faults, and InternalDeformation Adiacentto SoutheastAsia and the WesternPacific THOMAS J. FITCI-I 2 Lamont-Do.herty GeologicalObservatory o.• Columbia University,Palisades, New York 10964 A model for oblique convergencebetween plates of lithosphere is proposed in which at least a fraction of slip parallel to the plate margin results in transcurrent movements on a nearly vertical fault located on the continental side of a zone of plate consumption.In the extreme caseof complete decoupling,only the componentof slip normal to the plate margin can be inferred from underthrusting.Recent movementsin the western Sunda region provide the most convincingevidence for decouplingof slip, which in this region is thought to be oblique to the plate margin. A speculative model for convergencealong the margins of the Philippine Sea is constructedfrom an inferred direction of oblique slip in the Philippine region. This model requires that the triple point formed by the junction of the Japanese and Izu-Bonin trenches and the Nankai trough migrate along the Sagami trough. Absence of an offset between the trenches can be explained by rifting within the Izu-Bonin arc. Transcurrent movements in southwest.Japan and the Tai.wan region suggest that similar movements within well-developed island arcs are initiated during a nascent stage in the development of such plate margins and are often imposed on a pre-existing zone of weakness. The bulgelike configurationof the western margin of the Andaman basin is explained as a result of interarc extension within the western part of the basin. In the Indian Ocean plate south and west of this basin, strike-slip movements inferred from four mechanism solutions, two o.f which are reported in this work, suggest• distribution of stressin which axes of both maximum and minimum compressi.onare nearly horizontal, the stress maximum trending west of north. The larger recent earthquakes in the eastern Sunda region have resulted in deformation within the arc rather than shallow underthrusting at the inferred plate margin. A narrow region between the Celebes basin and the Philippine trench, including the Talaud Islands and a northern extensi.on of the Molucca basin, contains several zones of shallow thrusting. Mechanism solutions show that these movements trend E-W consistent with shortening normal to the arc-related structures in the region. Recent movements near the east coast of Luzon reveal a zone of underthrusting along the inner wall of a trough, marginal to the coast. There is an apparent hiatus in underthrusting between this zone and the one that follows the inner wall of the Philippine trench. Several of the earth's most extensive zones sibly the Nicaragua trough [Maldo•ada-Koer- of transcurrentfaulting are locatedwithin and dell, 196.6].With the exceptionof the Atacama strike parallel to active island arcs and arclike [Arabasz and Allen, 1970], the other fault structures.Allen [1965] discussedevidence for zonesshow evidenceof recent strike-slipmove- movements on three such faults: the Atacama ments contemporarywith plate consumptionin in Chile, the Longitudinal in Taiwan, and the the sameregion. In the work presentedhere such Philippine. To this list can be added the a systemof contrastingmovements is explained Semangkofault in Sumatra [e.g., Katili, 1970], by a model of convergencein which slip that is pbssiblythe median tectonic line in southwest obliqueto the plate margin is at least partially Japan [Karneko,1966; Okada, 1971], and pos- decoupled between parallel zones of trans- current faulting and underthrusting.A similar x Lamont-Doherty Geological Observatory con- model is proposedby Karig and Mammerickx tribution 1830. [1972] to explain an en echelon distribution 2 Now with Department of Geophysics and Geochemistry, The Australian National Univer- of oceanictroughs east of the New Hebrides sity, Canberra, Australia. arc south of 12øS. A schematic cross section of a decoupled Copyright • 1972 by the American Geophysical Union. plate margin is shown in Figure 1. The trans- 4432 •)LATE CONVERGENCEAND TRANSCURRENT FAULTS 4433 Asthenospher• • Asthenosphere Fig. 1. Vertical sectionof a well-developedisland arc in a region of oblique convergence. Decoupling hypothesisis illustrated by transcurrent movement on a vertical fault adjacent to the center of active volcanism. current fault is near an axis of a chain of active either the vertical or the inclined fault are volcanoes,as the Philippine and Semangko obtained by equating horizontal shear stress faults are (Figure 2). One mechanismsolution to the product of the normal stress and the for a recent earthquake shows evidence for coefficientof friction •: strike-slipmovement [Mo.l•ar and Sykes,1969] alongthe Nicaragua trough, a volcanic gra.b•n Vertical fault thatis nearlyparallel to anadjacent section F(cosa- /zsin a) - /zNH (1) of the Middle America trench. Coexistence of activevolcanism and transcurrent. faulting is Inclinedfault extensionunderstandablecan alsoin bethat weaka zone in horizontalof weakness shear,in F(cos a -- /zsin a sin$)sin $ - /zNH (2) and vice versa. A zone of weakness of a dif- where N• is the contribution to normal stress ferent origin can be inferredfor right-lateral from the hydrostaticload. When (1) > (2), movementsalong the median tectonic line horizontalshear occurson the vertical fault [Kaneko, 1966; Okado, 1971]. These move- rather than on the inclinedfault. When a dip mentsparallel 'a zoneof underthrustingalong of 30ø is assumedfor the inclinedfault, the the inner wall of the Nankai trough [e.g., inequalitysimplifies to cosa • (3 • sin e•)/2, Fitch and Scholz, 1971]. In place of recent in whichcase angles of obliqueslip as largeas volcanism,of whichthere is nonein this part 45ø satisfythe inequal!ty,if it is assumed of Japan[e.g., Matsuda e't al., 1967],narrow that • is about 0.7. This argumentis only metamorphicbelts, considered relics of Meso- slightlyweakened by usingan expressionfor zoicplate margins [Miyashiro, 1967], provide obliqueshear rather than horizontalshear in a zone of weakness conducive to horizontal (2). shear. Of the four regions of oblique convergence Decouplingof obliqueslip in the manner revealedby modelsbased on the 'assumption proposedhere is favoredin manyreal situa- of rigid plates[e.g., Le Pichon,1968], one tions becausea nearly verticalsurface con- servesas a type exampleof a plate margin centrates horizontal shear more effectively suchas that illustratedin Figure1. The region than an inclinedsurface of equal or greater is the westernSunda, where horizontal shear strength.This argumentis only weaklyde- and underthrustingoccur concurrently on the pendenton the angleof obliqueslip. Consider Semangkofault and alongthe inner wall of the simplemodel in Figure3, in whichuniform the Java trench,respectively. Directions and horizontalforce per unit area F in the direc- rates of convergencein this regionare com- tionof the slipvector is appliedto a.plate mar- puted from a simplifiedmodel that doesnot gin. Simpleconditions for horizontalshear on includeslip betweenthe Chinaand Eurasian 4434 THOMAS J. FITCH nearly parallels the island arc [Gumper, 1971]. 60N Similarly, underthrustingnorth of Puerto Rico parallelsthe plate margin in this regionmarked by the Puerto Rico trench. Near New Guinea, slip between the major plates is obscuredby movements between small intervening plates [Johnson and Molnar, 1972] and by possible internal deformation in western parts. of this region. A model for decoupled slip similar to that proposedfor the western Sunda arc is used to infer a direction of oblique convergencefor the Philippine arc. From this inference, al- though it is tenuous,a model is constructedfor o convergence along the eastern and western lOS margins of the Philippine Sea. For the western margin, directions and rates of convergence comefrom recent movements (measureddirectly or inferred from seismic evidence or both) Fig. 2. Plate boundaries and major transcur- rent faults in the Far East. Solid boundaries are within selected zones of shallow earthquakes. those that are well defined by recent shallow earth- The spreading history of the mid-oceansystem quakes [e.g., Bc•razangi•d Dorm•n, 1969]. Dashed of active ridgescannot be used,because no part curves extrapolate between well-defined bound- of this system passes through the Philippine aries. Dotted curves represent traces of known Sea. transcurrent faults of great length. MTL, median tectonic line; LF, Longitudinal fault; PF, Philip- No attempt is made to include specialregions pine fault; SF, Semangko fault; ST, Sagami such as interarc basins [Karig, 1970] in these trough. Plate margins east o.f New Guinea are models. Active extension within several of the from Johnso.n c•nd Molnar [ 1972]. basins marginal to the Philippine Sea and southeastAsia probably influencesthe rate and plates (Figure 2). In the absenceof a quan- direction of convergencealong adjacent frontal titative measure of this slip, large corrections arcs. The western part of the Andaman basin to slip vectorsin the Sundaregion are possible; (Figure 4) contains one or more centers.of however,such correctionsare unlikely because spreadingthat became active for the first time computed centers of rotation for the Indian Ocean and Eurasian (including China) plates are nearly 90 ø distant from this arc. The other regionsof oblique convergenceare the western Aleutians [e.g., McKenzie and Parker, 1967], northern
Load more

Recommended publications
  • Year 7 Mastery Booklet
    YEAR 7 MASTERY BOOKLET Unit 2 – Terrifying Tectonics 2019-2020 ARK CURRICLUM PROJECT Unit 2: Terrifying Tectonics What will I be learning this unit? By the end of this unit you will know all about earthquakes and volcanoes – what causes them and their impacts. You will investigate two case studies and will make an important decision about reducing future risks. Lesson 1: What is happening beneath our feet? In this lesson we learn to describe the structure of the earth and to compare its layers. Lesson 2: Why are the plates moving? In this lesson we learn how convection currents are formed and how this causes tectonic plate movement. We will use global maps to identify the main tectonic plates. Lesson 3: What are tectonic hazards and where do they occur? In this lesson we will learn to describe the global distribution of earthquakes and volcanoes, using continents and compass directions. We will also begin to understand the connection between plate boundaries and tectonic hazard distribution. Lesson 4: What causes an earthquake? In this lesson we will solve the mystery of why an earthquake happened in Sichuan in 2008 using a series of clues related to physical features and tectonic processes. Lesson 5: What were the impacts of the 2008 earthquake at Sichuan? In this lesson we are learning to describe and categorise the impacts of the 2008 Sichuan earthquake. We will start to explain why the effects were very severe. Lesson 6: What causes a volcano? In this lesson we are learning why volcanoes form at destructive plate boundaries using the case study of Volcán de Fuego in Guatemala.
    [Show full text]
  • Constraints on the Moho in Japan and Kamchatka
    Tectonophysics 609 (2013) 184–201 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Review Article Constraints on the Moho in Japan and Kamchatka Takaya Iwasaki a, Vadim Levin b,⁎, Alex Nikulin b, Takashi Iidaka a a Earthquake Research Institute, University of Tokyo, Japan b Rutgers University, NJ, USA article info abstract Article history: This review collects and systematizes in one place a variety of results which offer constraints on the depth Received 1 July 2012 and the nature of the Moho beneath the Kamchatka peninsula and the islands of Japan. We also include stud- Received in revised form 12 November 2012 ies of the Izu–Bonin volcanic arc. All results have already been published separately in a variety of venues, and Accepted 22 November 2012 the primary goal of the present review is to describe them in the same language and in comparable terms. Available online 3 December 2012 For both regions we include studies using artificial and natural seismic sources, such as refraction and reflec- tion profiling, detection and interpretation of converted-mode body waves (receiver functions), surface wave Keywords: Kamchatka dispersion studies (in Kamchatka) and tomographic imaging (in Japan). The amount of work done in Japan is Japan significantly larger than in Kamchatka, and resulting constraints on the properties of the crust and the upper- Crustal structure most mantle are more detailed. Upper-mantle structure Japan and Kamchatka display a number of similarities in their crustal structure, most notably the average Moho crustal thickness in excess of 30 km (typical of continental regions), and the generally gradational nature of the crust–mantle transition where volcanic arcs are presently active.
    [Show full text]
  • Large and Repeating Slow Slip Events in the Izu-Bonin Arc from Space
    LARGE AND REPEATING SLOW SLIP EVENTS IN THE IZU-BONIN ARC FROM SPACE GEODETIC DATA （伊豆小笠原弧における巨大スロー地震および繰り返し スロー地震の宇宙測地学的研究） by Deasy Arisa Department of Natural History Sciences Graduate School of Science, Hokkaido University September, 2016 Abstract The Izu-Bonin arc lies along the convergent boundary where the Pacific Plate subducts beneath the Philippine Sea Plate. In the first half of my three-year doctoral course, I focused on the slow deformation on the Izu Islands, and later in the second half, I focused on the slow deformation on the Bonin Islands. The first half of the study, described in Chapter V, is published as a paper, "Transient crustal movement in the northern Izu–Bonin arc starting in 2004: A large slow slip event or a slow back-arc rifting event?". Horizontal velocities of continuous Global Navigation Satellite System (GNSS) stations on the Izu Islands move eastward by up to ~1 cm/year relative to the stable part of the Philippine Sea Plate suggesting active back-arc rifting behind the northern part of the arc. We confirmed the eastward movement of the Izu Islands explained by Nishimura (2011), and later discussed the sudden accelerated movement in the Izu Islands detected to have occurred in the middle of 2004. I mainly discussed this acceleration and make further analysis to find out the possible cause of this acceleration. Here I report that such transient eastward acceleration, starting in the middle of 2004, resulted in ~3 cm extra movements in three years. I compare three different mechanisms possibly responsible for this transient movement, i.e. (1) postseismic movement of the 2004 September earthquake sequence off the Kii Peninsula far to the west, (2) a temporary activation of the back-arc rifting to the west dynamically triggered by seismic waves from a nearby earthquake, and (3) a large slow slip event in the Izu-Bonin Trench to the east.
    [Show full text]
  • Philippine Sea Plate Inception, Evolution, and Consumption with Special Emphasis on the Early Stages of Izu-Bonin-Mariana Subduction Lallemand
    Progress in Earth and Planetary Science Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction Lallemand Lallemand Progress in Earth and Planetary Science (2016) 3:15 DOI 10.1186/s40645-016-0085-6 Lallemand Progress in Earth and Planetary Science (2016) 3:15 Progress in Earth and DOI 10.1186/s40645-016-0085-6 Planetary Science REVIEW Open Access Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction Serge Lallemand1,2 Abstract We compiled the most relevant data acquired throughout the Philippine Sea Plate (PSP) from the early expeditions to the most recent. We also analyzed the various explanatory models in light of this updated dataset. The following main conclusions are discussed in this study. (1) The Izanagi slab detachment beneath the East Asia margin around 60–55 Ma likely triggered the Oki-Daito plume occurrence, Mesozoic proto-PSP splitting, shortening and then failure across the paleo-transform boundary between the proto-PSP and the Pacific Plate, Izu-Bonin-Mariana subduction initiation and ultimately PSP inception. (2) The initial splitting phase of the composite proto-PSP under the plume influence at ∼54–48 Ma led to the formation of the long-lived West Philippine Basin and short-lived oceanic basins, part of whose crust has been ambiguously called “fore-arc basalts” (FABs). (3) Shortening across the paleo-transform boundary evolved into thrusting within the Pacific Plate at ∼52–50 Ma, allowing it to subduct beneath the newly formed PSP, which was composed of an alternance of thick Mesozoic terranes and thin oceanic lithosphere.
    [Show full text]
  • Temporal Evolution of Fault Coupling Associated with the Occurrence of Slow Slip Events in Central Japan
    Temporal evolution of fault coupling associated with the occurrence of slow slip events in central Japan Lucile Bruhat∗y1 and Junichi Fukuda2 1Laboratoire de G´eologiede l'ENS { CNRS : UMR8538 { France 2Earthquake Research Institute { Japan Abstract Although interseismic coupling has often been considered to be stationary in time, there is increasing evidence that fault locking can vary both spatially and temporally during the interseismic period. The detection of transient slip behavior in the proximity of locked regions, such as slow slip events or decadal-scale uncoupling events, suggest in fact that the notion of a characteristic interseismic coupling distribution might not be appropriate. This study focuses on interseismic deformation rates in the southeastern part of the Kant¯o area in Japan. This region lies at junction of two subduction zones, leading to a particularly complicated tectonic setting. On the Eastern side, the Pacific plate subducts under the Okhotsk Plate at the Japan Trench, while the Sagami Trough to the south evidences the subduction of the Philippine Sea Plate under the Okhotsk Plate. The Philippine Sea Plate interface has hosted M8 megathrust earthquakes in the vicinity of Tokyo metropolitan area, such as the 1923 Great Kant¯oearthquake. Studies of interseismic deformation rates [Sagiya, (2004); Nishimura et al. (2007)] have shown that these megathrust events are consistent with the presence of a strongly locked asperity on the western extent of the Philippine Sea Plate interface at depths above 15-20km. Meanwhile, offshore the B¯os¯oPeninsula, i.e. on the eastern side of the interface, recurrent slow slip events have been detected in 1996, 2002, 2007, 2011, 2013-2014, and 2018.
    [Show full text]
  • Tsunami Deposits and Earthquake Recurrence Along the Nankai
    Tsunami deposits and earthquake recurrence along the Nankai, Suruga and Sagami Troughs OSAMU FUJIWARA1 and JUNKO KOMATSUBARA1 1: Active Fault Research Center, AIST, C7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan ([email protected]) INTRODUCTION Histories of great (M~8) subduction-zone earthquakes inferred from tsunami deposits span 3000 years for the Nankai and Suruga Troughs and nearly 10,000 years for the Sagami Trough. The inferred histories contain variable recurrence intervals. The shortest recurrence intervals, 100-200 years for the Nankai Trough and 150-300 years for the Sagami Trough, are similar to those known from written earthquake and tsunami records in the last 1300 years. Longer intervals inferred from the tsunami deposits probably reflect variability in rupture mode, incompleteness of geologic records, and insufficient research. 130E 140E GEOLOGICAL SETTING The Nankai, Suruga and Sagami Troughs comprising the northeastern subduction margin of the Philippine Sea plate are 40N seismically active areas in the world. The Philippine Sea plate converges with overriding plates at a rate of 49-42 mm/year along the Nankai Trough and 27 mm/year around the Sagami Trough (Seno et al., 1993, 1994). Several source areas (segments) 35N Japan are located along these troughs, each of which are 100 - 150 km long along the trough axis and potentially excites M8-class Trench earthquake accompanied by large tsunami and coastal uplift or subsidence. Earthquakes and tsunamis occurred from these areas have repeatedly damaged the Pacific coast of Japan, including Tokyo Nankai Trough and Osaka metropolitan areas. Trench Trench Izu-Ogasawara Izu-Ogasawara Fig.
    [Show full text]
  • Warping and Cracking of the Pacific Plate by Thermal Contraction
    1 Warping and Cracking of the Pacific Plate by Thermal Contraction David Sandwell & Yuri Fialko Scripps Institution of Oceanography, La Jolla, California, 92093-0225, USA Submitted to Journal of Geophysical Research, March 16, 2004. Lineaments in the gravity field and associated chains of volcanic ridges are widespread on the Pacific plate but are not yet explained by plate tectonics. We propose that they are warps and cracks in the plate caused by uneven thermal contraction of the cooling lithosphere. Top-down cooling of the plate produces large thermoelastic stress that is optimally released by lithospheric flexure between regularly spaced parallel cracks. Both the crack spacing and gravity amplitude are predicted by elastic plate theory and variational principle. Cracks along the troughs of the gravity lineaments provide conduits for the generation of volcanic ridges in agreement with new observations from satellite-derived gravity. Our model suggests that gravity lineaments are a natural consequence of lithospheric cooling so that convective rolls or mantle plumes are not required. Introduction Plate tectonics explains most of the topography of the deep ocean basins, but there is still debate regarding the origin of off-ridge features that are younger than the ambient lithosphere, and especially those that are not aligned with the autochtonic seafloor spreading fabric. The Pacific basin contains three main types of the young off-ridge lineaments (Figure 1). (i) Chains of shield volcanoes such as the Hawaiian-Emperor seamounts are well explained by the mantle plume model [Morgan, 1971; Sleep, 1992]. (ii) Gravity lineaments are prominent at 140-200 km wavelength and are aligned in the direction of absolute plate motion [Haxby and Wessel, 1986] (Figure 1b).
    [Show full text]
  • Seismotectonic Modeling of the Repeating M 7-Class Disastrous Odawara Earthquake in the Izu Collision Zone, Central Japan
    Earth Planets Space, 56, 843–858, 2004 Seismotectonic modeling of the repeating M 7-class disastrous Odawara earthquake in the Izu collision zone, central Japan Katsuhiko Ishibashi Research Center for Urban Safety and Security/Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan (Received February 16, 2004; Revised July 15, 2004; Accepted July 21, 2004) Odawara City in central Japan, in the northernmost margin of the Philippine Sea (PHS) plate, suffered from severe earthquake disasters five times during the last 400 years with a mean repeat time of 73 years; in 1633, 1703, 1782, 1853 and 1923. In this region, non-volcanic Izu outer arc (IOA), the easternmost part of the PHS plate, has been subducted beneath Honshu (Japanese main island), and volcanic Izu inner arc (IIA) on the west of IOA has made multiple collision against Honshu. I hypothesize ‘West-Sagami-Bay Fracture’ (WSBF) beneath Odawara, a north-south striking tear fault within the PHS plate that has separated the descending IOA crust from the buoyant IIA crust, through examinations of multiple collision process and the PHS plate configuration. WSBF is considered a blind causative fault of the 1633, 1782 and 1853 M 7 Odawara earthquakes, and is inferred to have ruptured also during the 1703 and 1923 great Kanto earthquakes simultaneously with the interplate main fault. A presumable asperity on WSBF just beneath Odawara seems to control the temporal regularity of earthquake occurrence. Though WSBF has not yet been detected directly, it is considered an essential tectonic element in this region, which might be a fracture zone with a few or several kilometer thickness actually.
    [Show full text]
  • UNIT 10 Plate Tectonics Study Guide
    UNIT 10 Plate Tectonics Study Guide Chapters 1, 2, 9, and most of book (Revised 7/18) UNIT 10 HOMEWORK worth 10 points VIDEO WEB HIT HOMEWORK: Write two paragraphs with minimum of three sentences each (PHYSICAL GEOLOGY 1303) (Revised 7//18) UNIT 10 Video Hits For Unit 10 Video Hit, go to the “DMC HOME” website; in Search box –type “Kramer”, select “Faculty Listing”; click on Walter Vernon Kramer, click on Website“, scroll down and click GEOL 1303; then select “Video Hit Link Number 10”, and click on icon, watch video of life forms that don’t need sunlight!. [IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED) General -Tectonics: the branch of geology that studies regional and global structural features on Earth -Plate tectonics: the unifying theory of global dynamics. The lithosphere is believed to be broken into individual plates that move in response to convection within the Earth’s upper mantle. -Plate tectonics theory explains the interrelationships of volcanoes, earthquakes, climate, mountains, and even evolution. Historical Studies of the Ocean Floor -Evidence for tall mountains under the Mid-Atlantic Ocean was presented in the 1850s. -The laying of the transatlantic telegraph cable 1860s proved that there was a mountain range in the middle of the Atlantic Ocean. 1850 map 1908 map FYI In 1878, Wyville Thompson compiled ocean depth data from the scientific sailing ship (the HMS Challenger) and collected samples of rock (basalt) from these deep-underwater mountains. Thirty years later in 1908, this data was compiled and the results further implied an extensive mid-Atlantic mountain range (which was largely ignored).
    [Show full text]
  • The Plate Theory for Volcanism
    This article was originally published in Encyclopedia of Geology, second edition published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author’s institution, for non-commercial research and educational use, including without limitation, use in instruction at your institution, sending it to specific colleagues who you know, and providing a copy to your institution’s administrator. All other uses, reproduction and distribution, including without limitation, commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution’s website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at: https://www.elsevier.com/about/policies/copyright/permissions Foulger Gillian R. (2021) The Plate Theory for Volcanism. In: Alderton, David; Elias, Scott A. (eds.) Encyclopedia of Geology, 2nd edition. vol. 3, pp. 879-890. United Kingdom: Academic Press. dx.doi.org/10.1016/B978-0-08-102908-4.00105-3 © 2021 Elsevier Ltd. All rights reserved. Author's personal copy The Plate Theory for Volcanism Gillian R Foulger, Department of Earth Sciences, Science Laboratories, Durham University, Durham, United Kingdom © 2021 Elsevier Ltd. All rights reserved. Statement of Plate Theory 879 Background, History, Development and Discussion 879 Lithospheric Extension 880 Melt in the Mantle 881 Studying Intraplate Volcanism 882 Examples 883 Iceland 883 Yellowstone 885 The Hawaii and Emperor Volcano Chains 886 Discussion 888 Summary 888 References 888 Further Reading 889 Statement of Plate Theory The Plate Theory for volcanism proposes that all terrestrially driven volcanism on Earth’s surface, including at unusual areas such as Iceland, Yellowstone and Hawaii, is a consequence of plate tectonics.
    [Show full text]
  • A Trench Fan in the Izu-Ogasawara Trench on the Boso Trench Triple Junction, Japan
    Marine Geology, 82 (1988) 235-249 235 Elsevier Science Publishers B.V., Amsterdam Printed in The Netherlands A TRENCH FAN IN THE IZU-OGASAWARA TRENCH ON THE BOSO TRENCH TRIPLE JUNCTION, JAPAN WONN SOH, ASAHIKO TAIRA and HIDEKAZU TOKUYAMA Ocean Research Institute, University of Tokyo, 1-15.1, Minamidai, Nakano-ku, Tokyo 164 (Japan) (Received November 20, 1987; revised and accepted January 12, 1988) Abstract Soh, W., Taira, A. and Tokuyama, H., 1988. A trench fan in the Izu Ogasawara Trench on the Boso Trench triple junction, Japan. Mar. Geol., 82: 235-249. The Mogi Trench Fan, 18 km in diameter, is located in the 9.1 km deep Izu Ogasawara Trench. Analysis of the morphology and internal structure of the Mogi Fan was based on 3.5 kHz records, seismic reflection profiles and Seabeam bathymetry. The Mogi Fan was fed from a point source, and displays an even-shaped partial cone morphology which can be divided into upper, middle and lower fans. The upper fan is defined as an apparent topographic mound, having a large-scale single channel with well-defined levees that appear to be composed mainly of coarse-grained turbidites. The middle fan is characterized by divergent channels and lobes. The lower fan is a smooth mound with no channel features. It is postulated that the lower fan is constructed chiefly by turbidity currents that reflected back from the higher outer slope. Seismic reflection records across the fan show deformation resulting from plate subduction in the upper fan; this deformation can be traced laterally to the lower bulge of the inner slope neighbouring the Mogi Fan.
    [Show full text]
  • Magnetic and Gravity Interpretation of Yaloc-69 Data from the Cocos Plate Area
    AN ABSTRACT OF THE THESIS OF Richard Shih-Ming Lu for the Master of Science (Name) (Degree) in Geophysics presented on ig-il (Major) (Date) Title:MAGNETIC AND GRAVITY INTERPRETATIONOF YALOC-69 DATA FROM THE COCOS PLATE AREA Abstract approved: Redacted for Privacy Donald F. Heinrichs Magnetic, gravity and bathymetry data werecollected on an ex- tended cruise of the R/V Yaquina in 1969.The last set of data was ob- tamed from those track lines leaving thePanama Basin.The area covered is mainly the Cocos plate (Molnarand Sykes, 1969).The data is analyzed and compared with resultsof previous workers and the geophysical implications considered. Generally speaking, from the magnetic partof the data, both direct and indirect methods show supportof Vine and Matthew's (1963) hypothesis of sea-floor spreadingand the subsequent principles of new global tectonics.The most northern magnetic anomaly profile across the East Pacific rise(at 18. 3°N) shows a spreading rate about 3 cm/yr. and the most southern one(at 12. 8°N) shows a rate about 5. 2 cm/yr.The Cocos plate has been assumed to movein a northeast- southwest direction(N30°E to N45°E), and rotate with respect to the Pacific plate about a pole at40°N, 11 0°W with an angular velocity of -7 19. 6x10 deg. /yr. (Larson and Chase, 1970).New material comes up from the west boundary -the East Pacific rise, and the south boundary - the Galapogos rift, causing theCocos plate to underthrust the Americans plate at the middle American arc.Some of the points of.
    [Show full text]