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Lin W, Yang B, Han B, Hu X. A Review of Subsurface Electrical Conductivity Anomalies in Magnetotelluric Imaging. SENSORS (BASEL, SWITZERLAND) 2023; 23:1803. [PMID: 36850401 PMCID: PMC9959437 DOI: 10.3390/s23041803] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
After 70 years of development, magnetotelluric (MT), a remote sensing technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration and the deep tectonic evolution of the Earth. The electrical resistivity anomalies and their quantitative interpretation are closely related to or even controlled by the interconnected high-conductivity phases, which are frequently associated with tectonic activity. Based on representative electrical resistivity studies mainly of the deep crust and mantle, we reviewed principal electrical conduction mechanisms, generally used conductivity mixing models, and potential causes of high-conductivity including the saline fluid, partial melting, graphite, sulfide, and hydrogen in nominally anhydrous minerals, and the general methods to infer the water content of the upper mantle through electrical anomaly revealed by MT.
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Affiliation(s)
- Wule Lin
- Hubei Subsurface Multi-Scale Imaging Key Laboratory, School of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
| | - Bo Yang
- Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 511458, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China
- China-Pakistan Joint Research Center on Earth Sciences, CAS-HEC, Islamabad 45320, Pakistan
| | - Bo Han
- Institute of Geological Survey, China University of Geosciences, Wuhan 430074, China
| | - Xiangyun Hu
- Hubei Subsurface Multi-Scale Imaging Key Laboratory, School of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
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Crustal Electrical Structure of the Ganzi Fault on the Eastern Tibetan Plateau: Implications for the Role of Fluids in Earthquakes. REMOTE SENSING 2022. [DOI: 10.3390/rs14132990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The initiation and evolution of seismic activity in intraplate regions are controlled by heterogeneous stress and highly fractured rocks within the rock mass triggered by fluid migration. In this study, we imaged the electrical structure of the crust beneath the Ganzi fault using a three-dimensional magnetotelluric inversion technique, which is host to an assemblage of resistive and conductive features extending into the lower crust. It presents a near-vertical low-resistance zone that cuts through the brittle ductile transition zone, extends to the lower crust, and acts as a pathway for fluid migration from the crustal flow to the upper crustal depths. Conductors in the upper and lower crust are associated with saline fluids and 7% to 16% partial melting, respectively. The relationship between the earthquake epicenter and the surrounding electrical structure suggests that the intraplate seismicity is triggered by overpressure fluids, which are dependent on fluid volume changes generated by the decompression dehydration of partially molten material during upwelling and native fluid within the crustal flow.
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Electrical Properties and Anisotropy of Schists and Fault Rocks from New Zealand’s Southern Alps under Confining Pressure. GEOSCIENCES 2022. [DOI: 10.3390/geosciences12030121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Magnetotelluric models spanning the Pacific–Australian Plate boundary in New Zealand’s South Island indicate a localized zone of low electrical resistivity that is spatially coincident with the ductile mid-crustal part of the Alpine Fault Zone (AFZ). We explored the source of this anomaly by measuring the electrical properties of samples collected from surface outcrops approaching the AFZ that have accommodated a gradient of systematic strain and deformation conditions. We investigated the effects of tectonite fabric, fluid saturated pore/fracture networks and surface conductivity on the bulk electrical response and the anisotropy of resistivity measured under increasing confining pressures up to 200 MPa. We find that porosity and resistivity increase while porosity and the change in anisotropy of resistivity with confining pressure (δ (ρ‖/ρ⊥)/δ (peff)) decreases approaching the AFZ, indicating the electrical response is controlled by pore fluid conductivity and modified during progressive metamorphism. Conversely, Alpine mylonites exhibit relatively low resistivities at low porosities, and lower δ (ρ‖/ρ⊥)/δ (peff) than the schists. These findings indicate a transition in both the porosity distribution and electrical charge transport processes in rocks that have experienced progressive grain size reduction and mixing of phases during development of mylonitic fabrics due to creep shear strain within the AFZ.
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Niemeijer AR, Boulton C, Toy VG, Townend J, Sutherland R. Large-displacement, hydrothermal frictional properties of DFDP-1 fault rocks, Alpine Fault, New Zealand: Implications for deep rupture propagation. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2016; 121:624-647. [PMID: 27610290 PMCID: PMC4994769 DOI: 10.1002/2015jb012593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 12/31/2015] [Accepted: 01/24/2016] [Indexed: 06/06/2023]
Abstract
The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65-75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP-1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity-strengthening behavior to velocity-weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity-weakening region restricted to higher velocity for higher temperatures. Friction was substantially lower for low-velocity shearing (V < 0.3 µm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate-and-state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity-strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle-plastic transition for quartzofeldspathic compositions.
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Affiliation(s)
- A. R. Niemeijer
- Faculty of Geosciences, HPT LaboratoryUtrecht UniversityUtrechtNetherlands
| | - C. Boulton
- Geology and Geophysics, School of Environmental SciencesUniversity of LiverpoolLiverpoolUK
| | - V. G. Toy
- Department of GeologyUniversity of OtagoDunedinNew Zealand
| | - J. Townend
- School of Geography, Environment and Earth SciencesVictoria University of WellingtonWellingtonNew Zealand
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Boese CM, Townend J, Smith E, Stern T. Microseismicity and stress in the vicinity of the Alpine Fault, central Southern Alps, New Zealand. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jb008460] [Citation(s) in RCA: 69] [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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Bertrand EA, Unsworth MJ, Chiang CW, Chen CS, Chen CC, Wu FT, Türkoğlu E, Hsu HL, Hill GJ. Magnetotelluric imaging beneath the Taiwan orogen: An arc-continent collision. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jb008688] [Citation(s) in RCA: 35] [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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Becken M, Ritter O, Bedrosian PA, Weckmann U. Correlation between deep fluids, tremor and creep along the central San Andreas fault. Nature 2011; 480:87-90. [DOI: 10.1038/nature10609] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Accepted: 09/28/2011] [Indexed: 11/09/2022]
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Thiel S, Heinson G. Crustal imaging of a mobile belt using magnetotellurics: An example of the Fowler Domain in South Australia. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb006698] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fluid and deformation regime of an advancing subduction system at Marlborough, New Zealand. Nature 2009; 460:733-6. [DOI: 10.1038/nature08204] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 06/08/2009] [Indexed: 11/09/2022]
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Muñoz G, Mateus A, Pous J, Heise W, Monteiro Santos F, Almeida E. Unraveling middle-crust conductive layers in Paleozoic Orogens through 3D modeling of magnetotelluric data: The Ossa-Morena Zone case study (SW Iberian Variscides). ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jb004987] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Eberhart-Phillips D, Chadwick M, Bannister S. Three-dimensional attenuation structure of central and southern South Island, New Zealand, from local earthquakes. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jb005359] [Citation(s) in RCA: 41] [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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Herman F, Braun J, Dunlap WJ. Tectonomorphic scenarios in the Southern Alps of New Zealand. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2004jb003472] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Frédéric Herman
- Research School of Earth Sciences; Australian National University; Canberra ACT Australia
| | - Jean Braun
- Research School of Earth Sciences; Australian National University; Canberra ACT Australia
| | - William J. Dunlap
- Research School of Earth Sciences; Australian National University; Canberra ACT Australia
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Sutherland R, Eberhart-Phillips D, Harris RA, Stern T, Beavan J, Ellis S, Henrys S, Cox S, Norris RJ, Berryman KR, Townend J, Bannister S, Pettinga J, Leitner B, Wallace L, Little TA, Cooper AF, Yetton M, Stirling M. Do great earthquakes occur on the Alpine Fault in central South Island, New Zealand? A CONTINENTAL PLATE BOUNDARY: TECTONICS AT SOUTH ISLAND, NEW ZEALAND 2007. [DOI: 10.1029/175gm12] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Geophysical structure of the Southern Alps Orogen, South Island, New Zealand. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/175gm04] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Ritter O, Hoffmann-Rothe A, Bedrosian PA, Weckmann U, Haak V. Electrical conductivity images of active and fossil fault zones. ACTA ACUST UNITED AC 2005. [DOI: 10.1144/gsl.sp.2005.245.01.08] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractWe compare recent magnetotelluric investigations of four large fault systems: (i) the actively deforming, ocean-continent interplate San Andreas Fault (SAF); (ii) the actively deforming, continent-continent interplate Dead Sea Transform (DST); (iii) the currently inactive, trench-linked intraplate West Fault (WF) in northern Chile; and (iv) the Waterberg Fault/Omaruru Lineament (WF/OL) in Namibia, a fossilized intraplate shear zone formed during early Proterozoic continental collision. These fault zones show both similarities and marked differences in their electrical subsurface structure. The central segment of the SAF is characterized by a zone of high conductivity extending to a depth of several kilometres and attributed to fluids within a highly fractured damage zone. The WF exhibits a less pronounced but similar fault-zone conductor (FZC) that can be explained by meteoric waters entering the fault zone. The DST appears different as it shows a distinct lack of a FZC and seems to act primarily as an impermeable barrier to cross-fault fluid transport. Differences in the electrical structure of these faults within the upper crust may be linked to the degree of deformation localization within the fault zone. At the DST, with no observable fault-zone conductor, strain may have been localized for a considerable time span along a narrow, metre-scale damage zone with a sustained strength difference between the shear plane and the surrounding host rock. In the case of the SAF, a positive correlation of conductance and fault activity is observed, with more active fault segments associated with wider, deeper and more conductive fault-zone anomalies. Fault-zone conductors, however, do not uniquely identify specific architectural or hydrological units of a fault. A more comprehensive whole-fault picture for the brittle crust can be developed in combination with seismicity and structural information. Giving a window into lower-crustal shear zones, the fossil WF/OL in Namibia is imaged as a subvertical, 14 km-deep, 10 km-wide zone of high and anisotropic conductivity. The present level of exhumation suggests that the WF/OL penetrated the entire crust as a relatively narrow shear zone. Contrary to the fluid-driven conductivity anomalies of active faults, the anomaly here is attributed to graphitic enrichment along former shear planes. Once created, graphite is stable over very long time spans and thus fault/shear zones may remain conductive long after activity ceases.
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Affiliation(s)
- O. Ritter
- GeoForschungsZentrum Potsdam, Telegrafenberg
D-14473 Potsdam, Germany
| | - A. Hoffmann-Rothe
- GeoForschungsZentrum Potsdam, Telegrafenberg
D-14473 Potsdam, Germany
| | - P. A. Bedrosian
- GeoForschungsZentrum Potsdam, Telegrafenberg
D-14473 Potsdam, Germany
| | - U. Weckmann
- GeoForschungsZentrum Potsdam, Telegrafenberg
D-14473 Potsdam, Germany
| | - V. Haak
- GeoForschungsZentrum Potsdam, Telegrafenberg
D-14473 Potsdam, Germany
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Van Avendonk HJA, Holbrook WS, Okaya D, Austin JK, Davey F, Stern T. Continental crust under compression: A seismic refraction study of South Island Geophysical Transect I, South Island, New Zealand. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003jb002790] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - W. Steven Holbrook
- Department of Geology and Geophysics; University of Wyoming; Laramie Wyoming USA
| | - David Okaya
- Department of Geological Sciences; University of Southern California; Los Angeles California USA
| | - Jeffrey K. Austin
- Department of Geology and Geophysics; University of Wyoming; Laramie Wyoming USA
| | - Fred Davey
- Institute of Geological and Nuclear Sciences; Lower Hutt New Zealand
| | - Tim Stern
- School of Earth Sciences; Victoria University of Wellington; Wellington New Zealand
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Connolly JAD, Podladchikov YY. Fluid flow in compressive tectonic settings: Implications for midcrustal seismic reflectors and downward fluid migration. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003jb002822] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J. A. D. Connolly
- Earth Sciences Department; Swiss Federal Institute of Technology; Zurich Switzerland
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Scherwath M. Lithospheric structure across oblique continental collision in New Zealand from wide-anglePwave modeling. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb002286] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Eberhart-Phillips D, Bannister S. Three-dimensional crustal structure in the Southern Alps region of New Zealand from inversion of local earthquake and active source data. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000567] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Stephen Bannister
- Institute of Geological and Nuclear Sciences; Lower Hutt New Zealand
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