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Spatial and Temporal Variations in Crustal Structure in the Eurasian Basin. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10020157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
To understand the tectonic–magmatic history, crustal structure and crustal accretion mode of the Eurasian Basin in the Arctic, we calculated the crustal thickness, residual bathymetry (RB) and non-isostatic topography of the Eurasian Basin by using the latest bathymetry, free-air gravity anomaly, crustal age and sediment thickness data. The tectonic–magmatic process of the Eurasian Basin can be divided into two stages. During magnetic isochrons 24-13 (C24-C13), the crustal structure of the basin was characterized by regional variations, while the crustal structure of the basin was characterized by local variations during magnetic isochrons 13-0 (C13-0). On the whole, the western part of the basin had a thicker crustal thickness and higher RB than the eastern part of the basin during C24-C13, which should result from the northward movement of Greenland. During magnetic isochrons 24-20 (C24-C20), the crustal structure of the eastern part of the basin had abnormally strong asymmetry. We speculate that there may be mantle upwelling beneath the Kara Sea Shelf in the south of the Eastern Eurasian Basin, which provides a large amount of melt for the crustal accretion of the southern part of the Eastern Eurasian Basin. The melt focusing supply could generate abnormally thick crust (>7 km) during magma enhancement period. The Western Eurasian Basin had stronger spatial variability and more frequency asymmetric polarity reversal than the Eastern Eurasian Basin during magnetic isochrons 6-0 (C6-0). We attribute this to the inflow of the North Atlantic mantle.
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Liu CZ, Wu FY, Liu T, Zhang C, Zhang WQ, Zhang ZY, Zhang Z, Wei W, Lin YZ. An origin of ultraslow spreading ridges for the Yarlung-Tsangpo ophiolites. FUNDAMENTAL RESEARCH 2022; 2:74-83. [PMID: 38933911 PMCID: PMC11197761 DOI: 10.1016/j.fmre.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/20/2021] [Accepted: 07/13/2021] [Indexed: 11/20/2022] Open
Abstract
As relics of ancient ocean lithosphere, ophiolites are the most important petrological evidence for marking the sutures and also play a key role in reconstructing plate configuration. They also provide valuable windows for studying crustal accretion and mantle processes occurring at modern ocean ridges. Abundant ophiolites are distributed along the Yarlung-Tsangpo suture and represent the relics of ocean lithosphere of the Neo-Tethys. They are characterized by an incomplete litho-stratigraphy, of which the mantle section is much thicker than the crustal section. Ocean crustal rocks outcropped in the Yarlung-Tsangpo ophiolites are much thinner than normal ocean crusts (~ 7 km) or even absent. Tectonic settings from which the Yarlung-Tsangpo ophiolites originated remain highly controversial, although an origin of the supra-subduction zone is prevailing. Moreover, their incomplete litho-stratigraphy has been commonly attributed to tectonic dismemberment during the late-stage emplacement after their formation. Nevertheless, such an incompleteness resembles the ocean lithosphere generated at modern ultraslow spreading ridges, such as the Southwest Indian Ridge (SWIR). In this paper, we present several lines of evidence that support the formation of the Yarlung-Tsangpo ophiolites at ultraslow spreading ridges, during which detachment faults were developed. This suggests that the Yarlung-Tsangpo ophiolites might represent the ocean core complexes (OCC) in the Neo-Tethys Ocean. The OCC with high topography in the seafloor were clogged in the trench and preserved as ophiolites through Indo-Eurasia collision. The clogging resulted in the demise of an old subduction and a new subduction was re-initiated beneath the clogged OCC.
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Affiliation(s)
- Chuan-Zhou Liu
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fu-Yuan Wu
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tong Liu
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Chang Zhang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Wei-Qi Zhang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen-Yu Zhang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Zhang
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wu Wei
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yin-Zheng Lin
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Grevemeyer I, Rüpke LH, Morgan JP, Iyer K, Devey CW. Extensional tectonics and two-stage crustal accretion at oceanic transform faults. Nature 2021; 591:402-407. [PMID: 33731945 DOI: 10.1038/s41586-021-03278-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/21/2021] [Indexed: 01/31/2023]
Abstract
Oceanic transform faults are seismically and tectonically active plate boundaries1 that leave scars-known as fracture zones-on oceanic plates that can cross entire ocean basins2. Current descriptions of plate tectonics assume transform faults to be conservative two-dimensional strike-slip boundaries1,3, at which lithosphere is neither created nor destroyed and along which the lithosphere cools and deepens as a function of the age of the plate4. However, a recent compilation of high-resolution multibeam bathymetric data from 41 oceanic transform faults and their associated fracture zones that covers all possible spreading rates shows that this assumption is incorrect. Here we show that the seafloor along transform faults is systemically deeper (by up to 1.6 kilometres) than their associated fracture zones, in contrast to expectations based on plate-cooling arguments. Accretion at intersections between oceanic ridges and transform faults seems to be strongly asymmetric: the outside corners of the intersections show shallower relief and more extensive magmatism, whereas the inside corners have deep nodal basins and seem to be magmatically starved. Three-dimensional viscoplastic numerical models show that plastic-shear failure within the deformation zone around the transform fault results in the plate boundary experiencing increasingly oblique shear at increasing depths below the seafloor. This results in extension around the inside corner, which thins the crust and lithosphere at the transform fault and is linked to deepening of the seafloor along the transform fault. Bathymetric data suggest that the thinned transform-fault crust is augmented by a second stage of magmatism as the transform fault intersects the opposing ridge axis. This makes accretion at transform-fault systems a two-stage process, fundamentally different from accretion elsewhere along mid-ocean ridges.
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Affiliation(s)
- Ingo Grevemeyer
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
| | - Lars H Rüpke
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Jason P Morgan
- Southern University of Science and Technology, Shenzhen, China
| | - Karthik Iyer
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.,GeoModelling Solutions, Zurich, Switzerland
| | - Colin W Devey
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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Haughton GA, Hayman NW, Searle RC, Le Bas T, Murton BJ. Volcanic-Tectonic Structure of the Mount Dent Oceanic Core Complex in the Ultraslow Mid-Cayman Spreading Center Determined From Detailed Seafloor Investigation. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS : G(3) 2019; 20:1298-1318. [PMID: 35860338 PMCID: PMC9285398 DOI: 10.1029/2018gc008032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 06/15/2023]
Abstract
The flanks of the ultraslow-spreading Mid-Cayman Spreading Center (MCSC) are characterized by domal massifs or oceanic core complexes (OCCs). The most prominent of these, Mount Dent, comprises lower-crustal and upper-mantle lithologies and hosts the Von Damm vent field ~12 km west of the axial deep. Here, presented autonomous underwater vehicle-derived swath sonar (multibeam) mapping and deep-towed side-scan sonar imagery lead to our interpretation that: (i) slip along the OCC-bounding detachment fault is ceasing, (ii) the termination zone, where detachment fault meets the hanging wall, is disintegrating, (iii) the domed surface of the OCC is cut by steep north-south extensional faulting, and (iv) the breakaway zone is cut by outward facing faults. The Von Damm vent field and dispersed pockmarks on the OCC's south flank further suggest that hydrothermal fluid flow is pervasive within the faulted OCC. On the axial floor of the MCSC, bright acoustic backscatter and multibeam bathymetry reveal: (v) a volcanic detachment hanging wall, (vi) a major fault rifting the southern flank of Mount Dent, and (vii) a young axial volcanic ridge intersecting its northern flank. These observations are described by a conceptual model wherein detachment faulting and OCC exhumation are ceasing during an increase in magmatic intrusion, brittle deformation, and hydrothermal circulation within the OCC. Together, this high-resolution view of the MCSC provides an instructive example of how OCCs, formed within an overall melt-starved ultraslow spreading center, can undergo magmatism, hydrothermal activity, and faulting in much the same way as expected in magmatically more robust slow-spreading centers elsewhere.
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Affiliation(s)
- G. A. Haughton
- School of Ocean and Earth SciencesUniversity of SouthamptonSouthamptonUK
| | - N. W. Hayman
- Institute for Geophysics, Jackson School for GeosciencesUniversity of TexasAustinTXUSA
| | - R. C. Searle
- Department of Earth SciencesDurham UniversityDurhamUK
| | - T. Le Bas
- National Oceanography CenterSouthamptonUK
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German CR, Lin J. The Thermal Structure of the Oceanic Crust, Ridge-Spreading and Hydrothermal Circulation: How Well do we Understand their Inter-Connections? MID-OCEAN RIDGES 2013. [DOI: 10.1029/148gm01] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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6
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Searle RC, Escartín J. The Rheology and Morphology of Oceanic Lithosphere and Mid-Ocean Ridges. MID-OCEAN RIDGES 2013. [DOI: 10.1029/148gm03] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Ultramafic-Mafic Plutonic Rock Suites Exposed Along the Mid-Atlantic Ridge (10°N-30°N). Symmetrical-Asymmetrical Distribution and Implications for Seafloor Spreading Processes. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm106p0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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8
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Macdonald KC. Linkages Between Faulting, Volcanism, Hydrothermal Activity and Segmentation on Fast Spreading Centers. FAULTING AND MAGMATISM AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm106p0027] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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9
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Structure of Modern Oceanic Crust and Ophiolites and Implications for Faulting and Magmatism at Oceanic Spreading Centers. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm106p0219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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10
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Karson JA. Internal Structure of Oceanic Lithosphere: A Perspective from Tectonic Windows. FAULTING AND MAGMATISM AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm106p0177] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Bird P, Kagan YY, Jackson DD. Plate Tectonics and Earthquake Potential of Spreading Ridges and Oceanic Transform Faults. PLATE BOUNDARY ZONES 2013. [DOI: 10.1029/gd030p0203] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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12
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Zhou H, Dick HJB. Thin crust as evidence for depleted mantle supporting the Marion Rise. Nature 2013; 494:195-200. [DOI: 10.1038/nature11842] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/11/2012] [Indexed: 11/09/2022]
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Ferguson DJ, Calvert AT, Pyle DM, Blundy JD, Yirgu G, Wright TJ. Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology. Nat Commun 2013; 4:1416. [DOI: 10.1038/ncomms2410] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 12/20/2012] [Indexed: 11/09/2022] Open
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Roland E, Lizarralde D, McGuire JJ, Collins JA. Seismic velocity constraints on the material properties that control earthquake behavior at the Quebrada-Discovery-Gofar transform faults, East Pacific Rise. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jb009422] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Escartín J, Lin J. Ridge offsets, normal faulting, and gravity anomalies of slow spreading ridges. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb03267] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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16
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Coulton AJ, Harper GD, O'Hanley DS. Oceanic versus emplacement age serpentinization in the Josephine ophiolite: Implications for the nature of the Moho at intermediate and slow spreading ridges. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb02157] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Wolfe CJ, Purdy GM, Toomey DR, Solomon SC. Microearthquake characteristics and crustal velocity structure at 29°N on the Mid-Atlantic Ridge: The architecture of a slow spreading segment. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb02399] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Cannat M, Fontaine F, Escartín J. Serpentinization and associated hydrogen and methane fluxes at slow spreading ridges. GEOPHYSICAL MONOGRAPH SERIES 2010. [DOI: 10.1029/2008gm000760] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Buck WR, Lavier LL, Poliakov ANB. Modes of faulting at mid-ocean ridges. Nature 2005; 434:719-23. [PMID: 15815620 DOI: 10.1038/nature03358] [Citation(s) in RCA: 285] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Accepted: 01/12/2005] [Indexed: 11/09/2022]
Abstract
Abyssal-hill-bounding faults that pervade the oceanic crust are the most common tectonic feature on the surface of the Earth. The recognition that these faults form at plate spreading centres came with the plate tectonic revolution. Recent observations reveal a large range of fault sizes and orientations; numerical models of plate separation, dyke intrusion and faulting require at least two distinct mechanisms of fault formation at ridges to explain these observations. Plate unbending with distance from the top of an axial high reproduces the observed dip directions and offsets of faults formed at fast-spreading centres. Conversely, plate stretching, with differing amounts of constant-rate magmatic dyke intrusion, can explain the great variety of fault offset seen at slow-spreading ridges. Very-large-offset normal faults only form when about half the plate separation at a ridge is accommodated by dyke intrusion.
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Affiliation(s)
- W Roger Buck
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA.
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Embley RW, Lupton JE. Diking, event plumes, and the subsurface biosphere at mid-ocean ridges. THE SUBSEAFLOOR BIOSPHERE AT MID-OCEAN RIDGES 2004. [DOI: 10.1029/144gm06] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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21
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Boettcher MS. Earthquake scaling relations for mid-ocean ridge transform faults. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jb003110] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Tivey MA, Schouten H, Kleinrock MC. A near-bottom magnetic survey of the Mid-Atlantic Ridge axis at 26°N: Implications for the tectonic evolution of the TAG segment. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb001967] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Maurice A. Tivey
- Department of Geology and Geophysics; Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
| | - Hans Schouten
- Department of Geology and Geophysics; Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
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23
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Smith DK, Escartin J, Cannat M, Tolstoy M, Fox CG, Bohnenstiehl DR, Bazin S. Spatial and temporal distribution of seismicity along the northern Mid-Atlantic Ridge (15°-35°N). ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb001964] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Deborah K. Smith
- Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
| | | | | | - Maya Tolstoy
- Lamont-Doherty Earth Observatory; Palisades New York USA
| | - Christopher G. Fox
- National Oceanic and Atmospheric Administration/Pacific Marine Environmental Laboratory; Newport Oregon USA
| | | | - Sara Bazin
- Institut de Physique du Globe de Paris; Paris France
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24
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Cochran JR, Kurras GJ, Edwards MH, Coakley BJ. The Gakkel Ridge: Bathymetry, gravity anomalies, and crustal accretion at extremely slow spreading rates. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb001830] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- James R. Cochran
- Lamont-Doherty Earth Observatory of Columbia University; Palisades New York USA
| | - Gregory J. Kurras
- Department of Geology and Geophysics, School of Ocean Earth Science and Technology; University of Hawaii; Honolulu Hawaii USA
| | - Margo H. Edwards
- Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology; University of Hawaii; Honolulu Hawaii USA
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Tucholke BE, Fujioka K, Ishihara T, Hirth G, Kinoshita M. Submersible study of an oceanic megamullion in the central North Atlantic. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jb000373] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Floyd JS, Mutter JC, Goodliffe AM, Taylor B. Evidence for fault weakness and fluid flow within an active low-angle normal fault. Nature 2001; 411:779-83. [PMID: 11459052 DOI: 10.1038/35081040] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Determining the composition and physical properties of shallow-dipping, active normal faults (dips < 35 degrees with respect to the horizontal) is important for understanding how such faults slip under low resolved shear stress and accommodate significant extension of the crust and lithosphere. Seismic reflection images and earthquake source parameters show that a magnitude 6.2 earthquake occurred at about 5 km depth on or close to a normal fault with a dip of 25-30 degrees located ahead of a propagating spreading centre in the Woodlark basin. Here we present results from a genetic algorithm inversion of seismic reflection data, which shows that the fault at 4-5 km depth contains a 33-m-thick layer with seismic velocities of about 4.3 km s(-1), which we interpret to be composed of serpentinite fault gouge. Isolated zones exhibit velocities as low as approximately 1.7 km s(-1) with high porosities, which we suggest are maintained by high fluid pressures. We propose that hydrothermal fluid flow, possibly driven by a deep magmatic heat source, and high extensional stresses ahead of the ridge tip have created conditions for fault weakness and strain localization on the low-angle normal fault.
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Affiliation(s)
- J S Floyd
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA.
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28
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Barclay AH, Toomey DR, Solomon SC. Microearthquake characteristics and crustalVP/VSstructure at the Mid-Atlantic Ridge, 35°N. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jb900371] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Canales JP, Collins JA, Escartín J, Detrick RS. Seismic structure across the rift valley of the Mid-Atlantic Ridge at 23°20′ (MARK area): Implications for crustal accretion processes at slow spreading ridges. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900301] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Chia CS, Makris NC, Fialkowski LT. A comparison of bistatic scattering from two geologically distinct abyssal hills. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2000; 108:2053-2070. [PMID: 11108343 DOI: 10.1121/1.1308047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The bistatic scattering characteristics of two geologically distinct abyssal hills located on the western flank of the Mid-Atlantic Ridge, known as B' and C', are experimentally compared using data acquired with low-frequency towed-array systems at 1/2 convergence zone (approximately 33 km) stand-off. The comparison is significant because the abyssal hills span the two classes of elevated seafloor crust that cover the Mid-Atlantic Ridge. The highly lineated B' feature is representative of abyssal hills composed of outside corner crust, the most commonly occurring category, whereas the domed C' promontory is representative of the rougher, low-aspect-ratio abyssal hills composed of inside corner crust. The latter are less common and usually restricted to segment valley margins. The mean biazimuthal scattering distributions of the two abyssal hills each exhibit Lambertian behavior with comparable albedos, suggesting that the distinction between abyssal hills composed of differing crust is not significant in modeling long-range reverberation. The adverse effect of using bathymetry that undersamples seafloor projected area in scattering strength analysis is also quantified with data from the B' ridge. Specifically, the use of undersampled bathymetry can lead to significant overestimates in the strength of seafloor scattering.
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Affiliation(s)
- CS Chia
- Massachusetts Institute of Technology, Cambridge 02139, USA
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31
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Embley RW, Chadwick WW, Perfit MR, Smith MC, Delaney JR. Recent eruptions on the CoAxial segment of the Juan de Fuca Ridge: Implications for mid-ocean ridge accretion processes. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900030] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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32
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Hooft EEE, Detrick RS, Toomey DR, Collins JA, Lin J. Crustal thickness and structure along three contrasting spreading segments of the Mid-Atlantic Ridge, 33.5°-35°N. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jb900442] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Canales JP, Detrick RS, Lin J, Collins JA, Toomey DR. Crustal and upper mantle seismic structure beneath the rift mountains and across a nontransform offset at the Mid-Atlantic Ridge (35°N). ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jb900379] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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Preston JR. Reverberation at the Mid-Atlantic Ridge during the 1993 ARSRP experiment seen by R/V Alliance from 200-1400 Hz and some modeling inferences. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2000; 107:237-259. [PMID: 10641634 DOI: 10.1121/1.428357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In July 1993 SACLANTCEN participated in an experiment for the Acoustic Reverberation Special Research Program (ARSRP). The primary objective was to take high resolution measurements to shed light on the detailed physical processes dominating the low frequency scattering from rough topographic features and from deep sediment pond areas. A very detailed set of monostatic and bistatic scattering experiments were conducted just west of the Mid-Atlantic Ridge near 26 degrees N, 47 degrees W. Results from SACLANTCEN's R/V ALLIANCE are presented which show monostatic and bistatic scattering from selected bathymetric features using pulsed sources from 200-1400 Hz and SUS charges. Area water depths ranged from 3300 to greater than 5200 m. The receivers were a horizontal array of 128 elements spaced at 0.5, 1, and 2 m. Source depths varied from 120 to 1200 m and receiver depths ranged from 400 to 500 m. Received reverberation levels are presented as functions of the estimated scatterer position on area bathymetry maps. Results show the same high scattering areas from one seamount were observed in three distinct frequency bands centered at 227, 350, and 700 Hz. Even at 1350 Hz the correlation of scattering highlights with nearby bathymetric features is quite good. Comparisons of measured reverberation and modeled reverberation are presented which suggest that the dominant longer range scattering from the large features is driven by the steep slopes present above the critical depth but that small scale roughness is also essential for strong backscatter.
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Affiliation(s)
- JR Preston
- ARL, The Pennsylvania State University, State College 16804, USA
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Gràcia E, Bideau D, Hekinian R, Lagabrielle Y. Detailed geological mapping of two contrasting second-order segments of the Mid-Atlantic Ridge between Oceanographer and Hayes fracture zones (33°30′N-35°N). ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900161] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Nicolas A, Boudier F, Meshi A. Slow spreading accretion and mantle denudation in the Mirdita ophiolite (Albania). ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900126] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Escartín J, Cowie PA, Searle RC, Allerton S, Mitchell NC, MacLeod CJ, Slootweg AP. Quantifying tectonic strain and magmatic accretion at a slow spreading ridge segment, Mid-Atlantic Ridge, 29°N. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998jb900097] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Thibaud R, Gente P, Maia M. A systematic analysis of the Mid-Atlantic Ridge morphology and gravity between 15°N and 40°N: Constraints of the thermal structure. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97jb02934] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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39
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Gao D, Hurst SD, Karson JA, Delaney JR, Spiess FN. Computer-aided interpretation of side-looking sonar images from the eastern intersection of the Mid-Atlantic Ridge with the Kane Transform. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb00165] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Blackman DK, Cann JR, Janssen B, Smith DK. Origin of extensional core complexes: Evidence from the Mid-Atlantic Ridge at Atlantis Fracture Zone. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb01756] [Citation(s) in RCA: 224] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Tivey MA, Tucholke BE. Magnetization of 0-29 Ma ocean crust on the Mid-Atlantic Ridge, 25°30′ to 27°10′N. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb01394] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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42
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Chaotic topography, mantle flow and mantle migration in the Australian–Antarctic discordance. Nature 1998. [DOI: 10.1038/29226] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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43
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Tucholke BE, Lin J, Kleinrock MC. Megamullions and mullion structure defining oceanic metamorphic core complexes on the Mid-Atlantic Ridge. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb00167] [Citation(s) in RCA: 401] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Smith SE, Casey JR, Bryan WB, Dmitriev L, Silantyev S, Magakyan R. Geochemistry of basalts from the Hayes Transform region of the Mid-Atlantic Ridge. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97jb03208] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Maia M, Gente P. Three-dimensional gravity and bathymetry analysis of the Mid-Atlantic Ridge between 20°N and 24°N: Flow geometry and temporal evolution of the segmentation. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97jb01635] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Lawrence RM, Karson JA, Hurst SD. Dike orientations, fault-block rotations, and the construction of slow spreading oceanic crust at 22°40′N on the Mid-Atlantic Ridge. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97jb02541] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Cochran JR, Sempéré JC. The Southeast Indian Ridge between 88°E and 118°E: Gravity anomalies and crustal accretion at intermediate spreading rates. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jb00511] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Goff JA, Ma Y, Shah A, Cochran JR, Sempéré JC. Stochastic analysis of seafloor morphology on the flank of the Southeast Indian Ridge: The influence of ridge morphology on the formation of abyssal hills. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jb00781] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Tucholke BE, Lin J, Kleinrock MC, Tivey MA, Reed TB, Goff J, Jaroslow GE. Segmentation and crustal structure of the western Mid-Atlantic Ridge flank, 25°25′-27°10′N and 0-29 m.y. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jb03896] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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50
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Jung WY, Vogt PR. A gravity and magnetic anomaly study of the extinct Aegir Ridge, Norwegian Sea. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jb03915] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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