Syn-kinematic emplacement of the Pangong metamorphic and magmatic complex along the Karakorum Fault (N Ladakh)

Rolland, Yan; Mahéo, Gweltaz; Pêcher, Arnaud; Villa, Igor M.

doi:10.1016/j.jseaes.2008.03.009

Cited by 54 publications

(77 citation statements)

References 72 publications

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“…If this is so, the Complex must have cooled across the leucogranite solidus of ∼700°C some time between 18 and 15 Ma, inferred to mark the time of peak magmatism Ravikant et al, 2009;Reichardt et al, 2010;Searle et al, 1998]. This was followed by cooling through the ∼500°C isotherm at around 13.5 Ma, based on three argon cooling age samples: (1) the one presented here, (2) the 13.8 ± 0.1 Ma from hornblende sample 212 from within the Tangtse gorge between Tangtse and Muglib by Dunlap et al [1998], and (3) the 13.6 ± 0.1 Ma from hornblende sample L441 by Rolland et al [2009].…”

Section: Metamorphism Cooling and Deformationmentioning

confidence: 95%

“…[17] There are a number of biotite schist layers in the area, ranging in composition from quartz and feldspar-rich psammitic schists, to muscovite and biotite-rich schists including garnet in places, and minor sillimanite [Rolland et al, 2009]. These layers range in thickness from tens of meters up to 300-400 m thick.…”

Section: Geology Of the Muglib Valley In The Pangong Tso Regionmentioning

confidence: 99%

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Structural complexity resulting from pervasive ductile deformation in the Karakoram Shear Zone, Ladakh, NW India

McCarthy

Weinberg

2010

Tectonics

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[1] The NW-SE trending, ∼800 km long, dextral Karakoram Shear Zone bounds southwest Tibet. We investigate an area immediately NW of the Pangong Lake where midcrustal rocks sections of the shear zone are exposed. Here, the dominant shear zone is characterized by dextral mylonitic rocks sheared at amphibolite facies and partly retrogressed to greenschist facies. These rocks define a kilometric, SE plunging inclinedto-recumbent fold in the footwall of a north directed, oblique dextral thrust that exhumed anatectic rocks of the Pangong Range. Argon cooling ages reveal that the Pangong Range cooled from ∼700°C to 300°C between ∼18-15 and ∼10 Ma, contemporaneously with overthrusting. Toward the SE, closer to the Pangong Lake, this kilometric fold is rotated from its NW-SE trend to an E-W trend, and the sense of shear changes to sinistral, with a broadly north directed thrusting component. The documented structures contradict predictions of normal movement in this area derived from considerations of rigid block behavior of the crust and support the interpretation that the system records dextral transpression. Thrusting and exhumation of the deeper and hot rocks exposed in the Pangong Range, folding of the thrust footwall, and the development of a sinistral E-W trending shear zone are all compatible with transpression caused by a northward push by a rigid indenter such as the Ladakh Batholith.

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Section: Metamorphism Cooling and Deformationmentioning

confidence: 95%

Section: Geology Of the Muglib Valley In The Pangong Tso Regionmentioning

confidence: 99%

Structural complexity resulting from pervasive ductile deformation in the Karakoram Shear Zone, Ladakh, NW India

McCarthy

Weinberg

2010

Tectonics

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“…Leloup & Kienast 1993;Lacassin et al 2004a,b;Valli et al 2007Valli et al , 2008Rolland et al 2008). A simple test of this theory would be that U-Pb monazite ages for peak metamorphism and magmatism would all have to date strike-slip motion along the faults.…”

Section: 'Rigid Block' Modelsmentioning

confidence: 99%

“…(1) Did the metamorphism along the Karakoram Fault result from shear heating Lacassin et al 2004a,b;Valli et al 2007Valli et al , 2008Rolland et al 2008), or was it earlier and unrelated to shearing motion along the fault (Searle et al 1990Phillips et al 2004; (2) Are the deformed leucogranites along the Karakoram Fault synkinematic with respect to strike-slip shearing Lacassin et al 2004a,b;Valli et al 2007Valli et al , 2008Rolland et al 2008;Weinberg & Mark 2008) Relationship between metamorphism, melting and strikeslip shearing…”

Section: Karakoram Faultmentioning

confidence: 99%

“…Only a few late leucogranite dykes cross-cut the ductile mylonites along both the Tangtse and Pangong strands of the Karakoram Fault, and none of these dykes cut the brittle faults. Rolland et al (2008) proposed that granulite (c. 800 8C, 5.5 kbar)-amphibolite (700-750 8C, 4-5 kbar) to greenschist facies assemblages were developed within the Karakoram Fault zone during strike-slip shearing and suggested that the 'Tangtse granite was emplaced syn-kinematically at the contact between a LT and the HT granulite facies'. They further suggested that 'Microstructures observed within the Tangtse granite exhibit a syn-magmatic dextral S-C fabric' and that 'the Tangtse granite is not offset by, but is rather emplaced within the Karakoram Fault'.…”

Section: Karakoram Faultmentioning

confidence: 99%

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Crustal–lithospheric structure and continental extrusion of Tibet

Searle

Elliott

Phillips

et al. 2011

JGS

240

154

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Crustal shortening and thickening to c. 70-85 km in the Tibetan Plateau occurred both before and mainly after the c. 50 Ma India-Asia collision. Potassic-ultrapotassic shoshonitic and adakitic lavas erupted across the Qiangtang (c. 50-29 Ma) and Lhasa blocks (c. 30-10 Ma) indicate a hot mantle, thick crust and eclogitic root during that period. The progressive northward underthrusting of cold, Indian mantle lithosphere since collision shut off the source in the Lhasa block at c. 10 Ma. Late Miocene-Pleistocene shoshonitic volcanic rocks in northern Tibet require hot mantle. We review the major tectonic processes proposed for Tibet including 'rigid-block', continuum and crustal flow as well as the geological history of the major strikeslip faults. We examine controversies concerning the cumulative geological offsets and the discrepancies between geological, Quaternary and geodetic slip rates. Low present-day slip rates measured from global positioning system and InSAR along the Karakoram and Altyn Tagh Faults in addition to slow long-term geological rates can only account for limited eastward extrusion of Tibet since Mid-Miocene time. We conclude that despite being prominent geomorphological features sometimes with wide mylonite zones, the faults cut earlier formed metamorphic and igneous rocks and show limited offsets. Concentrated strain at the surface is dissipated deeper into wide ductile shear zones.

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Age and structure of the Shyok suture in the Ladakh region of northwestern India: Implications for slip on the Karakoram fault system

et al. 2015

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A precise age for the collision of the Kohistan-Ladakh block with Eurasia along the Shyok suture zone (SSZ) is one key to understanding the accretionary history of Tibet and the tectonics of Eurasia during the India-Eurasia collision. Knowing the age of the SSZ also allows the suture to be used as a piercing line for calculating total offset along the Karakoram Fault, which effectively represents the SE border of the Tibetan Plateau and has played a major role in plateau evolution. We present a combined structural, geochemical, and geochronologic study of the SSZ as it is exposed in the Nubra region of India to test two competing hypotheses: that the SSZ is of Late Cretaceous or, alternatively, of Eocene age. Coarse-continental strata of the Saltoro Molasse, mapped in this area, contain detrital zircon populations suggestive of derivation from Eurasia despite the fact that the molasse itself is deposited unconformably onto Kohistan-Ladakh rocks, indicating that the molasse is postcollisional. The youngest population of detrital zircons in these rocks (approximately 92 Ma) and a U/Pb zircon date for a dike that cuts basal molasse outcrops (approximately 85 Ma) imply that deposition of the succession began in the Late Cretaceous. This establishes a minimum age for the SSZ and rules out the possibility of an Eocene collision between Kohistan-Ladakh and Eurasia. Our results support correlation of the SSZ with the Bangong suture zone in Tibet, which implies a total offset across the Karakoram Fault of approximately 130-190 km.

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Syn-kinematic emplacement of the Pangong metamorphic and magmatic complex along the Karakorum Fault (N Ladakh)

Cited by 54 publications

References 72 publications

Structural complexity resulting from pervasive ductile deformation in the Karakoram Shear Zone, Ladakh, NW India

Structural complexity resulting from pervasive ductile deformation in the Karakoram Shear Zone, Ladakh, NW India

Crustal–lithospheric structure and continental extrusion of Tibet

Age and structure of the Shyok suture in the Ladakh region of northwestern India: Implications for slip on the Karakoram fault system

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