Mechanics of V-shaped conjugate strike-slip faults and the corresponding continuum mode of continental deformation

V-shaped conjugate strike-slip faults occur widely on Earth, Venus, and Mars in the solar system. They commonly lie at 60°–75° in map view from the maximum compressive stress (σ 1 ) direction. This fault pattern cannot be explained directly by the Coulomb fracture criterion, which predicts the formation of X-shaped shear fractures at 30° from the σ 1 direction. Possible explanations of this odd fault geometry include rotation of early formed Coulomb fractures or reactivation of preexisting weakness. Here, we show that none of these mechanisms is feasible for the formation of a late Cenozoic conjugate strike-slip fault system in central Tibet. Instead, its initiation can be best explained by distributed deformation during the formation of two parallel and adjoining shear zones that have opposing senses of shear. Our suggestion is based on the current global positioning system (GPS) velocity field in Tibet, which can be divided into two east-trending shear zones: a northern left-slip zone consisting of active ENE-striking left-slip faults, and a southern right-slip zone consisting of active WNW-striking right-slip faults. The correlation between the GPS strain field and the fault pattern suggests that the central Tibet conjugate faults may have initiated as two sets of Riedel shears in the two parallel but separate shear zones. Because the two east-trending shear zones also experience north-south contraction, we refer to this mechanism of conjugate-fault formation as paired general-shear (PGS) deformation. Assuming a Newtonian fluid, the observed Tibetan GPS velocity field requires the paired shear zones to have formed either by gravitational spreading of the Tibetan lithosphere or a horizontal shear at the base of the upper crust or mantle lithosphere. We demonstrate the feasibility of the two inferred mechanisms for the formation of V-shaped conjugate faults using simple sandbox experiments. Our paired general-shear (PGS) model implies that the combined effect of the state of strain and the state of stress favors only one set (i.e., Riedel shear) of Coulomb conjugate shear fractures under general shear flow. It also requires continuum deformation rather than discrete extrusion tectonics as the most dominant mode of deformation during the late Cenozoic development of the central Tibetan Plateau.

[1]  A. Yin.  Cenozoic tectonic evolution of Asia: A preliminary synthesis , 2010 .

[2]  M. Taylor,et al.  Active structures of the Himalayan-Tibetan orogen and their relationships to earthquake distribution, contemporary strain field, and Cenozoic volcanism , 2009 .

[3]  James W. Head,et al.  Formation and evolution of Lakshmi Planum, Venus: Assessment of models using observations from geological mapping , 2008 .

[4]  R. Bendick,et al.  Reconciling lithospheric deformation and lower crustal flow beneath central Tibet , 2007 .

[5]  Edwin Nissen,et al.  Reinterpretation of the active faulting in central Mongolia , 2007 .

[6]  Peizhen Zhang,et al.  Present‐day crustal motion within the Tibetan Plateau inferred from GPS measurements , 2007 .

[7]  Richard W. Allmendinger,et al.  Strain and rotation rate from GPS in Tibet, Anatolia, and the Altiplano , 2007 .

[8]  J. Jackson,et al.  Active tectonics of the Turkish‐Iranian Plateau , 2006 .

[9]  R. Lacassin,et al.  Post 4 Ma initiation of normal faulting in southern Tibet. Constraints from the Kung Co half graben , 2006 .

[10]  D. McKenzie,et al.  Models of crustal flow in the India–Asia collision zone , 2006 .

[11]  G. Peltzer,et al.  Current slip rates on conjugate strike‐slip faults in central Tibet using synthetic aperture radar interferometry , 2006 .

[12]  Y. Hervouët,et al.  Spatial and temporal relationships between compression, strike-slip and extension in the Central Venezuelan Andes: Clues for Plio-Quaternary tectonic escape , 2006 .

[13]  P. Mann,et al.  An overview of the petroleum system of Maracaibo Basin , 2006 .

[14]  G. Axen,et al.  Late Cenozoic shortening in the west-central Alborz Mountains, northern Iran, by combined conjugate strike-slip and thin-skinned deformation , 2006 .

[15]  J. Chorowicz,et al.  Anatolian escape tectonics driven by Eocene crustal thickening and Neogene–Quaternary extensional collapse in the eastern Mediterranean region , 2006 .

[16]  A. Cruden,et al.  Surface topography and internal strain variation in wide hot orogens from three-dimensional analogue and two-dimensional numerical vice models , 2006, Geological Society, London, Special Publications.

[17]  S. Klemperer.  Crustal flow in Tibet: geophysical evidence for the physical state of Tibetan lithosphere, and inferred patterns of active flow , 2006, Geological Society, London, Special Publications.

[18]  D. Montgomery,et al.  Continental-scale salt tectonics on Mars and the origin of Valles Marineris and associated outflow channels , 2006 .

[19]  D. Cunningham.  Active intracontinental transpressional mountain building in the Mongolian Altai: Defining a new class of orogen , 2005 .

[20]  Chun-yong Wang,et al.  Constraining the extent of crust-mantle coupling in central Asia using GPS, geologic, and shear wave splitting data [rapid communication] , 2005 .

[21]  Seismic anisotropy in western Tibet , 2005 .

[22]  D. Sims,et al.  Evaluating sand and clay models: do rheological differences matter? , 2005 .

[23]  T. Harrison,et al.  Nyainqentanglha Shan: A window into the tectonic, thermal, and geochemical evolution of the Lhasa block, southern Tibet , 2005 .

[24]  T. Harrison,et al.  Cretaceous-Tertiary shortening, basin development, and volcanism in central Tibet , 2005 .

[25]  Bernhard Wieneke,et al.  Shear localisation and strain distribution during tectonic faulting—new insights from granular-flow experiments and high-resolution optical image correlation techniques , 2005 .

[26]  Q. Zhang,et al.  Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism , 2005 .

[27]  P. Kapp,et al.  Indian punch rifts Tibet , 2004 .

[28]  Jeffrey Huang,et al.  Tomographic Inversion of Pn Travel Times in China: Implications for lithosphere thinning and deformation of North China , 2004 .

[29]  Peizhen Zhang,et al.  Continuous deformation of the Tibetan Plateau from global positioning system data , 2004 .

[30]  Wang-Ping Chen,et al.  Earthquakes Beneath the Himalayas and Tibet: Evidence for Strong Lithospheric Mantle , 2004, Science.

[31]  L. Jolivet,et al.  Backarc extension and collision: an experimental approach to the tectonics of Asia , 2004 .

[32]  James Jackson,et al.  Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates , 2004 .

[33]  R. Lacassin,et al.  Large-scale geometry, offset and kinematic evolution of the Karakorum fault, Tibet , 2004 .

[34]  S. Haines,et al.  About the lithospheric structure of central Tibet, based on seismic data from the INDEPTH III profile , 2004 .

[35]  S. Marshak.  Salients, Recesses, Arcs, Oroclines, and SyntaxesA Review of Ideas Concerning the Formation of Map-view Curves in Fold-thrust Belts , 2004 .

[36]  K. Priestley,et al.  Metamorphism, Metastability, Mechanical Strength, and the Support of Mountain Belts , 2004 .

[37]  L. Ding,et al.  Cenozoic Volcanism in Tibet: Evidence for a Transition from Oceanic to Continental Subduction , 2003 .

[38]  J. Malavieille,et al.  Neogene extension and volcanism in the Kunlun Fault Zone, northern Tibet: New constraints on the age of the Kunlun Fault , 2003 .

[39]  Mathilde Vergnolle,et al.  GPS measurements of crustal deformation in the Baikal‐Mongolia area (1994–2002): Implications for current kinematics of Asia , 2003 .

[40]  T. Harrison,et al.  Mesozoic and Cenozoic tectonic evolution of the Shiquanhe area of western Tibet , 2003 .

[41]  T. Harrison,et al.  Tectonic evolution of the early Mesozoic blueschist‐bearing Qiangtang metamorphic belt, central Tibet , 2003 .

[42]  T. Pavlis,et al.  Chasing the Garlock: A study of tectonic response to vertical axis rotation , 2003 .

[43]  J. Saul,et al.  Seismic Images of Crust and Upper Mantle Beneath Tibet: Evidence for Eurasian Plate Subduction , 2002, Science.

[44]  Christopher K. Morley,et al.  The origin and evolution of complex transfer zones (graben shifts) in conjugate fault systems around the Funan Field, Pattani Basin, Gulf of Thailand , 2002 .

[45]  J. Jackson.  Strength of the continental lithosphere: Time to abandon the jelly sandwich? , 2002 .

[46]  M. Brookfield,et al.  The geology and petroleum potential of the North Afghan platform and adjacent areas (northern Afghanistan, with parts of southern Turkmenistan, Uzbekistan and Tajikistan) , 2001 .

[47]  Zhenhan Wu,et al.  Normal faulting in central Tibet since at least 13.5 Myr ago , 2001, Nature.

[48]  C. Morley,et al.  Late Oligocene - Recent stress evolution in rift basins of northern and central Thailand: Implications for escape tectonics , 2001 .

[49]  C. Morley.  Combined escape tectonics and subduction rollback–back arc extension: a model for the evolution of Tertiary rift basins in Thailand, Malaysia and Laos , 2001, Journal of the Geological Society.

[50]  A. Casas,et al.  Analogue models of transpressive systems , 2001 .

[51]  Wenjin Zhao,et al.  Seismic polarization anisotropy beneath the central Tibetan Plateau , 2000 .

[52]  A. Yin.  Mode of Cenozoic east‐west extension in Tibet suggesting a common origin of rifts in Asia during the Indo‐Asian collision , 2000 .

[53]  D. Hilton,et al.  Southern limit of mantle-derived geothermal helium emissions in Tibet: implications for lithospheric structure , 2000 .

[54]  Leigh H. Royden,et al.  Topographic ooze: Building the eastern margin of Tibet by lower crustal flow , 2000 .

[55]  An Yin,et al.  Geologic Evolution of the Himalayan-Tibetan Orogen , 2000 .

[56]  P. DeCelles,et al.  High times on the Tibetan Plateau: Paleoelevation of the Thakkhola graben, Nepal , 2000 .

[57]  T. Harrison,et al.  Blueschist-bearing metamorphic core complexes in the Qiangtang block reveal deep crustal structure of northern Tibet , 2000 .

[58]  S. Marshak,et al.  Controls on the geometry of fold-thrust belt salients , 1999 .

[59]  T. Harrison,et al.  Significant late Neogene east-west extension in northern Tibet , 1999 .

[60]  P. Davis,et al.  Comparison of shear wave splitting and finite strain from the India‐Asia collision zone , 1997 .

[61]  P. Cobbold,et al.  Least squares restoration of Tertiary thrust sheets in map view, Tajik depression, central Asia , 1997 .

[62]  X. Wang,et al.  Did the Indo-Asian collision alone create the Tibetan plateau? , 1997 .

[63]  Wang,et al.  Surface Deformation and Lower Crustal Flow in Eastern Tibet , 1997, Science.

[64]  Thomas J. Owens,et al.  Implications of crustal property variations for models of Tibetan plateau evolution , 1997, nature.

[65]  Handong Tan,et al.  Partially Molten Middle Crust Beneath Southern Tibet: Synthesis of Project INDEPTH Results , 1996, Science.

[66]  L. Royden.  Coupling and decoupling of crust and mantle in convergent orogens: Implications for strain partitioning in the crust , 1996 .

[67]  U. Schärer,et al.  The Ailao Shan-Red River shear zone (Yunnan, China), Tertiary transform boundary of Indochina , 1995 .

[68]  A. Nercessian,et al.  Seismic anisotropy as an indicator of mantle flow beneath the Himalayas and Tibet , 1995, Nature.

[69]  T. Harrison,et al.  Activation of the Nyainqentanghla Shear Zone: Implications for uplift of the southern Tibetan Plateau , 1995 .

[70]  K. Hodges,et al.  Evidence for Tibetan plateau uplift before 14 Myr ago from a new minimum age for east–west extension , 1995, Nature.

[71]  T. Harrison,et al.  Tertiary structural evolution of the Gangdese Thrust System, southeastern Tibet , 1994 .

[72]  H. Perroud,et al.  Paleomagnetic evidence for Cenozoic block rotations in the Tadjik depression (Central Asia) , 1994 .

[73]  E. Fielding,et al.  Erosion and tectonics at the margins of continental plateaus , 1994 .

[74]  Eric J. Fielding,et al.  How flat is Tibet , 1994 .

[75]  M. Alavi.  TECTONICS OF THE ZAGROS OROGENIC BELT OF IRAN - NEW DATA AND INTERPRETATIONS , 1994 .

[76]  Kerry E Sieh,et al.  HOLOCENE SLIP RATE OF THE CENTRAL GARLOCK FAULT IN SOUTHEASTERN SEARLES VALLEY, CALIFORNIA , 1993 .

[77]  H. Perroud,et al.  A paleomagnetic study of Tertiary formations from the Kyrgyz Tien‐Shan and its tectonic implications , 1993 .

[78]  R. E. Powell.  Chapter 1: Balanced palinspastic reconstruction of pre-late Cenozoic paleogeology, southern California: Geologic and kinematic constraints on evolution of the San Andreas fault system , 1993 .

[79]  Declan G. De Paor,et al.  Strain and kinematic analysis in general shear zones , 1993 .

[80]  Giorgio Ranalli,et al.  Critical stress difference, fault orientation and slip direction in anisotropic rocks under non-Andersonian stress systems , 1992 .

[81]  Kerry E Sieh,et al.  Surficial offsets on the Central and Eastern Garlock Fault associated with prehistoric earthquakes , 1991 .

[82]  P. Davy,et al.  Experiments on shortening of a 4-layer model of the continental lithosphere , 1991 .

[83]  L. Jolivet,et al.  Right‐lateral shear along the Northwest Pacific Margin and the India‐Eurasia Collision , 1990 .

[84]  P. Molnar,et al.  Right-lateral shear and rotation as the explanation for strike-slip faulting in eastern Tibet , 1990, Nature.

[85]  Philip England,et al.  Extension during continental convergence, with application to the Tibetan Plateau , 1989 .

[86]  P. Molnar,et al.  Fault plane solutions of earthquakes and active tectonics of the Tibetan Plateau and its margins , 1989 .

[87]  A. Yin.  Origin of regional, rooted low-angle normal faults: A mechanical model and its tectonic implications , 1989 .

[88]  R. Armijo,et al.  Late Cenozoic right‐lateral strike‐slip faulting in southern Tibet , 1989 .

[89]  J. Dewey,et al.  Tectonic evolution of the India/Eurasia collision zone , 1989 .

[90]  J. Brun,et al.  Some Experiments on Block Rotation in the Brittle Upper Crust , 1989 .

[91]  G. Lister,et al.  The origin of metamorphic core complexes and detachment faults formed during Tertiary continental extension in the northern Colorado River region, U.S.A. , 1989 .

[92]  G. Peltzer,et al.  Formation and evolution of strike‐slip faults, rifts, and basins during the India‐Asia Collision: An experimental approach , 1988 .

[93]  A. Sylvester.  Strike-slip faults , 1988 .

[94]  François Robert,et al.  High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits , 1988 .

[95]  G. Mandl.  Mechanics of Tectonic Faulting: Models and Basic Concepts , 1988 .

[96]  P. Davy,et al.  Indentation tectonics in nature and experiment. I: Experiments scaled for gravity , 1988 .

[97]  G. Mandl.  Tectonic deformation by rotating parallel faults: the bookshelf mechanism , 1987 .

[98]  R. Armijo,et al.  Quaternary extension in southern Tibet: Field observations and tectonic implications , 1986 .

[99]  Philip England,et al.  FINITE STRAIN CALCULATIONS OF CONTINENTAL DEFORMATION .2. COMPARISON WITH THE INDIA-ASIA COLLISION ZONE , 1986 .

[100]  J. Jackson,et al.  A block model of distributed deformation by faulting , 1986, Journal of the Geological Society.

[101]  G. Peltzer,et al.  On the mechanics of the collision between India and Asia , 1986, Geological Society, London, Special Publications.

[102]  G. Mandl,et al.  Fault geometries in basement-induced wrench faulting under different initial stress states , 1986 .

[103]  P. Coney,et al.  Cordilleran metamorphic core complexes: Cenozoic extensional relics of Mesozoic compression , 1984 .

[104]  A. Nur,et al.  Block rotation by strike-slip faulting: Structural and paleomagnetic evidence , 1984 .

[105]  James Jackson,et al.  Active tectonics of the Alpine—Himalayan Belt between western Turkey and Pakistan , 1984 .

[106]  A. Nercessian,et al.  Lhasa block and bordering sutures— a continuation of a 500-km Moho traverse through Tibet , 1984, Nature.

[107]  P. R. Cobbold,et al.  Propagating extrusion tectonics in Asia: New insights from simple experiments with plasticine , 1982 .

[108]  P. Tapponnier,et al.  Mesozoic ophiolites, sutures, and arge-scale tectonic movements in Afghanistan , 1981 .

[109]  A. Şengör,et al.  Post-collisional tectonics of the Turkish-Iranian plateau and a comparison with Tibet , 1979 .

[110]  Gregory A. Davis,et al.  Garlock Fault: An Intracontinental Transform Structure, Southern California , 1973 .

[111]  R. E. Wilcox,et al.  Basic Wrench Tectonics , 1973 .

[112]  G. Mandl,et al.  Fully Developed Plastic Shear Flow of Granular Materials , 1970 .

[113]  J. Tchalenko.  Similarities between Shear Zones of Different Magnitudes , 1970 .

[114]  R. Freund.  Rotation of Strike Slip Faults in Sistan, Southeast Iran , 1970, The Journal of Geology.

[115]  J. Tchalenko,et al.  Structural Analysis of the Dasht-e Bayaz (Iran) Earthquake Fractures , 1970 .

[116]  F. Donath.  EXPERIMENTAL STUDY OF SHEAR FAILURE IN ANISOTROPIC ROCKS , 1961 .

[117]  E. M. Anderson,et al.  The dynamics of faulting : and dyke formation with applications to Britain , 1953, Geological Magazine.

[118]  M. King Hubbert,et al.  Theory of scale models as applied to the study of geologic structures , 1937 .