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Tian X, Behn MD, Ito G, Schierjott JC, Kaus BJP, Popov AA. Magmatism controls global oceanic transform fault topography. Nat Commun 2024; 15:1914. [PMID: 38429287 PMCID: PMC10907720 DOI: 10.1038/s41467-024-46197-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
Oceanic transform faults play an essential role in plate tectonics. Yet to date, there is no unifying explanation for the global trend in broad-scale transform fault topography, ranging from deep valleys to shallow topographic highs. Using three-dimensional numerical models, we find that spreading-rate dependent magmatism within the transform domain exerts a first-order control on the observed spectrum of transform fault depths. Low-rate magmatism results in deep transform valleys caused by transform-parallel tectonic stretching; intermediate-rate magmatism fully accommodates far-field stretching, but strike-slip motion induces across-transform tension, producing transform strength dependent shallow valleys; high-rate magmatism produces elevated transform zones due to local compression. Our models also address the observation that fracture zones are consistently shallower than their adjacent transform fault zones. These results suggest that plate motion change is not a necessary condition for reproducing oceanic transform topography and that oceanic transform faults are not simple conservative strike-slip plate boundaries.
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Affiliation(s)
- Xiaochuan Tian
- Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, USA.
| | - Mark D Behn
- Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, USA
| | - Garrett Ito
- Department of Earth Sciences, University of Hawaii, Honolulu HI, USA
| | - Jana C Schierjott
- Department of Earth Sciences, University of Hawaii, Honolulu HI, USA
| | - Boris J P Kaus
- Institute of Geosciences, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Anton A Popov
- Institute of Geosciences, Johannes Gutenberg University Mainz, Mainz, Germany
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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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Marjanović M, Singh SC, Gregory EPM, Grevemeyer I, Growe K, Wang Z, Vaddineni V, Laurencin M, Carton H, Gómez de la Peña L, Filbrandt C. Seismic Crustal Structure and Morphotectonic Features Associated With the Chain Fracture Zone and Their Role in the Evolution of the Equatorial Atlantic Region. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2020; 125:e2020JB020275. [PMID: 33282617 PMCID: PMC7685155 DOI: 10.1029/2020jb020275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/31/2020] [Accepted: 09/01/2020] [Indexed: 06/12/2023]
Abstract
Oceanic transform faults and fracture zones (FZs) represent major bathymetric features that keep the records of past and present strike-slip motion along conservative plate boundaries. Although they play an important role in ridge segmentation and evolution of the lithosphere, their structural characteristics, and their variation in space and time, are poorly understood. To address some of the unknowns, we conducted interdisciplinary geophysical studies in the equatorial Atlantic Ocean, the region where some of the most prominent transform discontinuities have been developing. Here we present the results of the data analysis in the vicinity of the Chain FZ, on the South American Plate. The crustal structure across the Chain FZ, at the contact between ∼10 and 24 Ma oceanic lithosphere, is sampled along seismic reflection and refraction profiles. We observe that the crustal thickness within and across the Chain FZ ranges from ∼4.6-5.9 km, which compares with the observations reported for slow-slipping transform discontinuities globally. We attribute this presence of close to normal oceanic crustal thickness within FZs to the mechanism of lateral dike propagation, previously considered to be valid only in fast-slipping environments. Furthermore, the combination of our results with other data sets enabled us to extend the observations to morphotectonic characteristics on a regional scale. Our broader view suggests that the formation of the transverse ridge is closely associated with a global plate reorientation that was also responsible for the propagation and for shaping lower-order Mid-Atlantic Ridge segmentation around the equator.
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Affiliation(s)
- Milena Marjanović
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Satish C. Singh
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Emma P. M. Gregory
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Ingo Grevemeyer
- GEOMAR Helmholtz Centre of Ocean Research Kiel, RD4—Marine GeodynamicsKielGermany
| | - Kevin Growe
- Applied Geophysics ProgramTU Delft, ETH Zürich, RWTH AachenAachenGermany
| | - Zhikai Wang
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Venkata Vaddineni
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Muriel Laurencin
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Hélène Carton
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | | | - Christian Filbrandt
- GEOMAR Helmholtz Centre of Ocean Research Kiel, RD4—Marine GeodynamicsKielGermany
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Fornari D, Tivey M, Schouten H, Perfit M, Yoerger D, Bradley A, Edwards M, Haymon R, Scheirer D, Von Damm K, Shank T, Soule A. Submarine Lava Flow Emplacement at the East Pacific Rise 9°50´N: Implications for Uppermost Ocean Crust Stratigraphy and Hydrothermal Fluid Circulation. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/148gm08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Abstract
Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.
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Affiliation(s)
- Taras Gerya
- Swiss Federal Institute of Technology Zurich, Department of Geosciences, Zurich, Switzerland.
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Toomey DR, Jousselin D, Dunn RA, Wilcock WSD, Detrick RS. Skew of mantle upwelling beneath the East Pacific Rise governs segmentation. Nature 2007; 446:409-14. [PMID: 17377578 DOI: 10.1038/nature05679] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 02/08/2007] [Indexed: 11/08/2022]
Abstract
Mantle upwelling is essential to the generation of new oceanic crust at mid-ocean ridges, and it is generally assumed that such upwelling is symmetric beneath active ridges. Here, however, we use seismic imaging to show that the isotropic and anisotropic structure of the mantle is rotated beneath the East Pacific Rise. The isotropic structure defines the pattern of magma delivery from the mantle to the crust. We find that the segmentation of the rise crest between transform faults correlates well with the distribution of mantle melt. The azimuth of seismic anisotropy constrains the direction of mantle flow, which is rotated nearly 10 degrees anticlockwise from the plate-spreading direction. The mismatch between the locus of mantle melt delivery and the morphologic ridge axis results in systematic differences between areas of on-axis and off-axis melt supply. We conclude that the skew of asthenospheric upwelling and transport governs segmentation of the East Pacific Rise and variations in the intensity of ridge crest processes.
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Affiliation(s)
- Douglas R Toomey
- Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA.
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Sohn RA. Fine-scale seismic structure of the shallow volcanic crust on the East Pacific Rise at 9°50′N. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jb003152] [Citation(s) in RCA: 25] [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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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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Van Avendonk HJA, Harding AJ, Orcutt JA, McClain JS. Contrast in crustal structure across the Clipperton transform fault from travel time tomography. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jb900459] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lundstrom CC, Sampson DE, Perfit MR, Gill J, Williams Q. Insights into mid-ocean ridge basalt petrogenesis: U-series disequilibria from the Siqueiros Transform, Lamont Seamounts, and East Pacific Rise. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900081] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [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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12
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Van Avendonk HJA, Harding AJ, Orcutt JA, McClain JS. A two-dimensional tomographic study of the Clipperton transform fault. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb00904] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Begnaud ML, McClain JS, Barth GA, Orcutt JA, Harding AJ. Velocity structure from forward modeling of the eastern ridge-transform intersection area of the Clipperton Fracture Zone, East Pacific Rise. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jb03393] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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