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Sternai P. Surface processes forcing on extensional rock melting. Sci Rep 2020; 10:7711. [PMID: 32382159 PMCID: PMC7206043 DOI: 10.1038/s41598-020-63920-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/30/2020] [Indexed: 11/09/2022] Open
Abstract
Surface processes and magmatism condition the structural evolution of continental rifts and passive margins through mechanical and thermal effects on the lithosphere rheology. However, their inter-relationships in extensional settings are largely unknown. Here, I use coupled thermo-mechanical geodynamic and landscape evolution numerical modeling to assess the links between erosion of rift shoulders, sedimentation within the rift basin and extensional rock melting. Results suggest that, when the crust is thinner than ~40 km, the extension rate is slower than ~2 cm/yr and the mantle potential temperature is below ~1230 °C, efficient surface processes may double crustal melting by Moho lowering and inhibit mantle decompression melting by ~50% through sediment loading within the rift basin. It is thus likely that surface processes significantly influenced the magmatic activity of a number of extensional settings worldwide - e.g. the Mediterranean, the Gulf of California, the Iberia-Newfoundland margin, and the South China Sea. Because magmatism and surface processes affect jointly the geological carbon cycle, the surface processes forcing on extensional rock melting investigated here involves an additional means of linkage between plate tectonics and climate changes.
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Affiliation(s)
- Pietro Sternai
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy.
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Seismic evidence for a mantle suture and implications for the origin of the Canadian Cordillera. Nat Commun 2019; 10:2249. [PMID: 31113959 PMCID: PMC6529410 DOI: 10.1038/s41467-019-09804-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 03/22/2019] [Indexed: 11/09/2022] Open
Abstract
The origin of the North American Cordillera and its affinity with the bounding craton are subjects of contentious debate. The mechanisms of orogenesis are rooted in two competing hypotheses known as the accretionary and collisional models. The former model attributes the Cordillera to an archetypal accretionary orogen comprising a collage of exotic terranes. The latter, less popular view argues that the Cordillera is a collisional product between an allochthonous ribbon microcontinent and cratonic North America. Here we present new seismic evidence of a sharp and structurally complex Cordillera-craton boundary in the uppermost mantle beneath the southern Canadian Cordillera, which can be interpreted as either a reshaped craton margin or a Late Cretaceous collisional boundary based on the respective hypotheses. This boundary dips steeply westward underneath a proposed (cryptic) suture in the foreland, consisent with the predicted location and geometry of the mantle suture, thus favoring a collisional origin.
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Zhao LF, Mousavi SM. Lateral Variation of Crustal Lg Attenuation in Eastern North America. Sci Rep 2018; 8:7285. [PMID: 29740108 PMCID: PMC5940689 DOI: 10.1038/s41598-018-25649-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/25/2018] [Indexed: 11/09/2022] Open
Abstract
We perform Q Lg tomography for the northeastern part of North America. Vertical broadband seismograms of 473 crustal earthquakes recorded by 302 stations are processed to extract the Lg amplitude spectra. Tomographic inversions are independently conducted at 58 discrete frequencies distributed evenly in log space between 0.1 and 20.0 Hz. This relatively large dataset with good ray coverage allows us to image lateral variation of the crustal attenuation over the region. Obtained Q Lg maps at broadband and individual frequencies provide new insights into the crustal attenuation of the region and its relationship to geological structures and past tectonic activity in the area. The Q Lg shows more uniform values over the older, colder, and drier Canadian Shield, in contrast to higher variations in the younger margins. Results confirm the correlation of large-scale variations with crustal geological features in the area. Existence of low-velocity anomalies, thick sediments, volcanic rocks, and thin oceanic crust are potential sources of observed anomalies. The mean Q values are inversely correlated with average heat flow/generation for main geological provinces.
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Affiliation(s)
- Lian-Feng Zhao
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, P.R. China
| | - S Mostafa Mousavi
- Department of Geophysics, Stanford University, Stanford, CA, 94305, USA.
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Mooney WD, Kaban MK. The North American upper mantle: Density, composition, and evolution. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jb000866] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bouligand C, Glen JMG, Blakely RJ. Mapping Curie temperature depth in the western United States with a fractal model for crustal magnetization. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009jb006494] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Roy M, Jordan TH, Pederson J. Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere. Nature 2009; 459:978-82. [DOI: 10.1038/nature08052] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 04/06/2009] [Indexed: 11/09/2022]
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Liu L, Spasojević S, Gurnis M. Reconstructing Farallon Plate Subduction Beneath North America Back to the Late Cretaceous. Science 2008; 322:934-8. [DOI: 10.1126/science.1162921] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Lijun Liu
- Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA
| | - Sonja Spasojević
- Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael Gurnis
- Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA
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Cammarano F, Romanowicz B. Insights into the nature of the transition zone from physically constrained inversion of long-period seismic data. Proc Natl Acad Sci U S A 2007; 104:9139-44. [PMID: 17483461 PMCID: PMC1890460 DOI: 10.1073/pnas.0608075104] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Imposing a thermal and compositional significance to the outcome of the inversion of seismic data facilitates their interpretation. Using long-period seismic waveforms and an inversion approach that includes constraints from mineral physics, we find that lateral variations of temperature can explain a large part of the data in the upper mantle. The additional compositional signature of cratons emerges in the global model as well. Above 300 km, we obtain seismic geotherms that span the range of expected temperatures in various tectonic regions. Absolute velocities and gradients with depth are well constrained by the seismic data throughout the upper mantle, except near discontinuities. The seismic data are consistent with a slower transition zone and an overall faster shallow upper mantle, which is not compatible with a homogenous dry pyrolite composition. A gradual enrichment with depth in a garnet-rich component helps to reduce the observed discrepancies. A hydrated transition zone would help to lower the velocities in the transition zone, but it does not explain the seismic structure above it.
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Affiliation(s)
- Fabio Cammarano
- Berkeley Seismological Laboratory, University of California, 215 McCone Hall, Berkeley, CA 94720, USA.
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Reston TJ. The formation of non-volcanic rifted margins by the progressive extension of the lithosphere: the example of the West Iberian margin. ACTA ACUST UNITED AC 2007. [DOI: 10.1144/sp282.5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractNon-volcanic margins such as the West Iberian margin exhibit certain characteristics, such as a deficit of synrift igneous rock, a zone of exhumed subcontinental mantle in the continent–ocean transition and an apparent extension discrepancy. These observations can be explained as a consequence of the progressive extension of the lithosphere above relatively cool mantle. The evolving rheological stratification of the lithosphere controls the style of extension at different lithospheric levels at different times; extension is probably heterogeneous at all stages, with lower crustal and upper mantle boudinage controlling the patterns of thinning and mantle upwelling early in the rift history, and complete crustal embrittlement and mantle serpentinization controlling the formation of late-stage detachment faults. Extension in the brittle crust is via multiple phases of faulting, with a general focusing of extension towards the incipient ocean.The lack of melt is explained by a combination of heterogeneous extension of the lower lithosphere and a cool subcontinental geotherm. The extension discrepancy may in places be controlled by depth-dependent stretching of the crust through lower crustal boudinage, but may also simply be the result of incomplete recognition of the entire polyphase faulting history. The latter seems to be the case for West Iberia.Evidence for all these processes can be found at the West Iberian rifted margins as well as those preserved and partially exposed in the Alps.
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Affiliation(s)
- T. J. Reston
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
- IFM-GEOMAR, Wischhofstrasse 1-3, D24148 Kiel, Germany (e-mail: )
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Hafkenscheid E, Wortel MJR, Spakman W. Subduction history of the Tethyan region derived from seismic tomography and tectonic reconstructions. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jb003791] [Citation(s) in RCA: 239] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Waite GP, Schutt DL, Smith RB. Models of lithosphere and asthenosphere anisotropic structure of the Yellowstone hot spot from shear wave splitting. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jb003501] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gregory P. Waite
- Department of Geology and Geophysics; University of Utah; Salt Lake City Utah USA
| | - Derek L. Schutt
- Department of Geology and Geophysics; University of Wyoming; Laramie Wyoming USA
| | - Robert B. Smith
- Department of Geology and Geophysics; University of Utah; Salt Lake City Utah USA
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Karlstrom KE, Whitmeyer SJ, Dueker K, Williams ML, Bowring SA, Levander AR, Humphreys ED, Keller GR. Synthesis of results from the CD-ROM Experiment: 4-D image of the lithosphere beneath the Rocky Mountains and implications for understanding the evolution of continental lithosphere. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/154gm31] [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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Freed AM, Bürgmann R. Evidence of power-law flow in the Mojave desert mantle. Nature 2004; 430:548-51. [PMID: 15282602 DOI: 10.1038/nature02784] [Citation(s) in RCA: 249] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 06/24/2004] [Indexed: 11/08/2022]
Abstract
Studies of the Earth's response to large earthquakes can be viewed as large rock deformation experiments in which sudden stress changes induce viscous flow in the lower crust and upper mantle that lead to observable postseismic surface deformation. Laboratory experiments suggest that viscous flow of deforming hot lithospheric rocks is characterized by a power law in which strain rate is proportional to stress raised to a power, n (refs 2, 3). Most geodynamic models of flow in the lower crust and upper mantle, however, resort to newtonian (linear) stress-strain rate relations. Here we show that a power-law model of viscous flow in the mantle with n = 3.5 successfully explains the spatial and temporal evolution of transient surface deformation following the 1992 Landers and 1999 Hector Mine earthquakes in southern California. A power-law rheology implies that viscosity varies spatially with stress causing localization of strain, and varies temporally as stress evolves, rendering newtonian models untenable. Our findings are consistent with laboratory-derived flow law parameters for hot and wet olivine--the most abundant mineral in the upper mantle--and support the contention that, at least beneath the Mojave desert, the upper mantle is weaker than the lower crust.
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Affiliation(s)
- Andrew M Freed
- Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
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