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Vlaha DR, Zuza AV, Chen L, Harlaux M. Hot Cordilleran hinterland promoted lower crust mobility and decoupling of Laramide deformation. Nat Commun 2024; 15:3750. [PMID: 38704380 PMCID: PMC11069518 DOI: 10.1038/s41467-024-48182-8] [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: 11/30/2023] [Accepted: 04/23/2024] [Indexed: 05/06/2024] Open
Abstract
The Late Cretaceous to Paleogene Laramide orogen in the North American Cordillera involved deformation >1,000 km from the plate margin that has been attributed to either plate-boundary end loading or basal traction exerted on the upper plate from the subducted Farallon flat slab. Prevailing tectonic models fail to explain the relative absence of Laramide-aged (ca. 90-60 Ma) contractional deformation within the Cordillera hinterland. Based on Raman spectroscopy of carbonaceous material thermometry and literature data from the restored upper 15-20 km of the Cordilleran crust we reconstruct the Late Cretaceous thermal architecture of the hinterland. Interpolation of compiled temperature data (n = 200) through a vertical crustal column reveals that the hinterland experienced a continuous but regionally elevated, upper-crustal geothermal gradient of >40 °C/km during Laramide orogenesis, consistent with peak metamorphic conditions and synchronous peraluminous granitic plutonism. The hot and partially melted hinterland promoted lower crust mobility and crust-mantle decoupling during flat-slab traction.
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Affiliation(s)
- Dominik R Vlaha
- Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV, USA.
- Department of Geological Sciences and Engineering, University of Nevada, Reno, NV, USA.
- Nevada Geosciences, University of Nevada, Reno, NV, USA.
| | - Andrew V Zuza
- Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV, USA
- Nevada Geosciences, University of Nevada, Reno, NV, USA
| | - Lin Chen
- State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
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Liu M, Gao H. Role of subduction dynamics on the unevenly distributed volcanism at the Middle American subduction system. Sci Rep 2023; 13:14697. [PMID: 37679365 PMCID: PMC10484906 DOI: 10.1038/s41598-023-41740-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023] Open
Abstract
A typical subduction of an oceanic plate beneath a continent is expected to be accompanied by arc volcanoes along the convergent margin. However, subduction of the Cocos plate at the Middle American subduction system has resulted in an uneven distribution of magmatism/volcanism along strike. Here we construct a new three-dimensional shear-wave velocity model of the entire Middle American subduction system, using full-wave ambient noise tomography. Our model reveals significant variations of the oceanic plates along strike and down dip, in correspondence with either weakened or broken slabs after subduction. The northern and southern segments of the Cocos plate, including the Mexican flat slab subduction, are well imaged as high-velocity features, where a low-velocity mantle wedge exists and demonstrate a strong correlation with the arc volcanoes. Subduction of the central Cocos plate encounters a thick high-velocity feature beneath North America, which hinders the formation of a typical low-velocity mantle wedge and arc volcanoes. We suggest that the presence of slab tearing at both edges of the Mexican flat slab has been modifying the mantle flows, resulting in the unusual arc volcanism.
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Affiliation(s)
- Meng Liu
- Department of Earth, Geographic, and Climate Sciences, University of Massachusetts Amherst, 627 North Pleasant St., Amherst, MA, 01003, USA.
| | - Haiying Gao
- Department of Earth, Geographic, and Climate Sciences, University of Massachusetts Amherst, 627 North Pleasant St., Amherst, MA, 01003, USA
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Huang Y, Nakatani T, Nakamura M, McCammon C. Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties. Nat Commun 2019; 10:5557. [PMID: 31804479 PMCID: PMC6895192 DOI: 10.1038/s41467-019-13513-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 11/08/2019] [Indexed: 11/30/2022] Open
Abstract
Recently, high electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. This implies that the for-arc mantle wedge is permeable for aqueous fluids. Here, we precisely determine the dihedral (wetting) angle in an olivine–NaCl–H2O system at fore-arc mantle conditions to assess the effect of salinity of subduction-zone fluids on the fluid connectivity. We find that NaCl significantly decreases the dihedral angle to below 60° in all investigated conditions at concentrations above 5 wt% and, importantly, even at 1 wt% at 2 GPa. Our results show that slab-released fluid forms an interconnected network at relatively shallow depths of ~80 km and can partly reach the fore-arc crust without causing wet-melting and serpentinization of the mantle. Fluid transport through this permeable window of mantle wedge accounts for the location of the high electrical conductivity anomalies detected in fore-arc regions. The authors here perform experiments to investigate the dihedral angle of olivine-H2O and olivine-H2O-NaCl systems. The observed effect of NaCl to decrease dihedral angles allows fluids to percolate through forearc mantle wedge and to accumulate in the overlying crust, accounting for the high electrical conductivity anomalies in forearc regions.
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Affiliation(s)
- Yongsheng Huang
- Department of Earth Science, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
| | - Takayuki Nakatani
- Department of Earth Science, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Michihiko Nakamura
- Department of Earth Science, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Catherine McCammon
- Bayerisches Geoinstitut, University of Bayreuth, 95440, Bayreuth, Germany
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Earthquake swarms and slow slip on a sliver fault in the Mexican subduction zone. Proc Natl Acad Sci U S A 2019; 116:7198-7206. [PMID: 30910959 DOI: 10.1073/pnas.1814205116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Mexican subduction zone is an ideal location for studying subduction processes due to the short trench-to-coast distances that bring broad portions of the seismogenic and transition zones of the plate interface inland. Using a recently generated seismicity catalog from a local network in Oaxaca, we identified 20 swarms of earthquakes (M < 5) from 2006 to 2012. Swarms outline what appears to be a steeply dipping structure in the overriding plate, indicative of an origin other than the plate interface. This steeply dipping structure corresponds to the northern boundary of the Xolapa terrane. In addition, we observed an interesting characteristic of slow slip events (SSEs) where they showed a shift from trenchward motion toward an along-strike direction at coastal GPS sites. A majority of the swarms were found to correspond in time to the along-strike shift. We propose that swarms and SSEs are occurring on a sliver fault that allows the oblique convergence to be partitioned into trench-perpendicular motion on the subduction interface and trench-parallel motion on the sliver fault. The resistivity structure surrounding the sliver fault suggests that SSEs and swarms of earthquakes occur due to high fluid content in the fault zone. We propose that the sliver fault provides a natural pathway for buoyant fluids attempting to migrate upward after being released from the downgoing plate. Thus, sliver faults could be responsible for the downdip end of the seismogenic zone by creating drier conditions on the subduction interface trenchward of the sliver fault, promoting fast-slip seismogenic rupture behavior.
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Gao X, Wang K. Rheological separation of the megathrust seismogenic zone and episodic tremor and slip. Nature 2017; 543:416-419. [PMID: 28264194 DOI: 10.1038/nature21389] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/05/2017] [Indexed: 11/09/2022]
Abstract
Episodic tremor and accompanying slow slip, together called ETS, is most often observed in subduction zones of young and warm subducting slabs. ETS should help us to understand the mechanics of subduction megathrusts, but its mechanism is still unclear. It is commonly assumed that ETS represents a transition from seismic to aseismic behaviour of the megathrust with increasing depth, but this assumption is in contradiction with an observed spatial separation between the seismogenic zone and the ETS zone. Here we propose a unifying model for the necessary geological condition of ETS that explains the relationship between the two zones. By developing numerical thermal models, we examine the governing role of thermo-petrologically controlled fault zone rheology (frictional versus viscous shear). High temperatures in the warm-slab environment cause the megathrust seismogenic zone to terminate before reaching the depth of the intersection of the continental Mohorovičić discontinuity (Moho) and the subduction interface, called the mantle wedge corner. High pore-fluid pressures around the mantle wedge corner give rise to an isolated friction zone responsible for ETS. Separating the two zones is a segment of semi-frictional or viscous behaviour. The new model reconciles a wide range of seemingly disparate observations and defines a conceptual framework for the study of slip behaviour and the seismogenesis of major faults.
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Affiliation(s)
- Xiang Gao
- Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.,Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao 266061, China
| | - Kelin Wang
- Pacific Geoscience Centre, Geological Survey of Canada, Natural Resources Canada, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada.,School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
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Mapping the Distribution of Fluids in the Crust and Lithospheric Mantle Utilizing Geophysical Methods. LECTURE NOTES IN EARTH SYSTEM SCIENCES 2013. [DOI: 10.1007/978-3-642-28394-9_13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Brudzinski MR, Hinojosa-Prieto HR, Schlanser KM, Cabral-Cano E, Arciniega-Ceballos A, Diaz-Molina O, DeMets C. Nonvolcanic tremor along the Oaxaca segment of the Middle America subduction zone. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2008jb006061] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kim Y, Clayton RW, Jackson JM. Geometry and seismic properties of the subducting Cocos plate in central Mexico. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb006942] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Iglesias A, Clayton RW, Pérez-Campos X, Singh SK, Pacheco JF, García D, Valdés-González C. Swave velocity structure below central Mexico using high-resolution surface wave tomography. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb006332] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Chen T, Clayton RW. Seismic attenuation structure in central Mexico: Image of a focused high-attenuation zone in the mantle wedge. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jb005964] [Citation(s) in RCA: 26] [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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Song TRA, Helmberger DV, Brudzinski MR, Clayton RW, Davis P, Pérez-Campos X, Singh SK. Subducting slab ultra-slow velocity layer coincident with silent earthquakes in southern Mexico. Science 2009; 324:502-6. [PMID: 19390043 DOI: 10.1126/science.1167595] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Great earthquakes have repeatedly occurred on the plate interface in a few shallow-dipping subduction zones where the subducting and overriding plates are strongly locked. Silent earthquakes (or slow slip events) were recently discovered at the down-dip extension of the locked zone and interact with the earthquake cycle. Here, we show that locally observed converted SP arrivals and teleseismic underside reflections that sample the top of the subducting plate in southern Mexico reveal that the ultra-slow velocity layer (USL) varies spatially (3 to 5 kilometers, with an S-wave velocity of approximately 2.0 to 2.7 kilometers per second). Most slow slip patches coincide with the presence of the USL, and they are bounded by the absence of the USL. The extent of the USL delineates the zone of transitional frictional behavior.
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Affiliation(s)
- Teh-Ru Alex Song
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road N.W., Washington, DC 20015, USA.
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Husker A, Davis PM. Tomography and thermal state of the Cocos plate subduction beneath Mexico City. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jb006039] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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