Tectonics of the Nanga Parbat syntaxis and the western Himalaya: an introduction

Treloar, Peter J.; Searle, Michael P.; Khan, Muhammad Asif; Jan, M. Qasim

doi:10.1144/gsl.sp.2000.170.01.01

Cited by 16 publications

(12 citation statements)

References 24 publications

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“…Concerning the two domains evidenced at a regional scale and separated by the Raikhot fault, the different observed stress patterns probably reflect two different stages of the tectonic activity, of different ages. East of the Raikhot fault, most of the Nanga Parbat pop‐up anticline was in the ductile deformation field up to recently, as indicated by 4 to 11 Ma monazite U/Pb ages obtained on the high‐grade migmatitic gneisses [ Smith et al , 1992], 1 to 5 Ma Ar/Ar cooling ages of biotite obtained in these gneisses [ Treloar et al , 2000; Schneider et al , 2001], the intrusion of granites as young as 1 Ma [ Zeitler at al. , 1993], and the shallow (5–6 km) present‐day brittle‐ductile transition as revealed by seismic investigations [ Meltzer et al , 2001].…”

Section: Discussionmentioning

confidence: 99%

Stress field evolution in the northwest Himalayan syntaxis, northern Pakistan

et al. 2008

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pp. 26International audienceWe have conducted a systematic inversion of striated fault planes throughout northern Pakistan in order to better depict the temporal and spatial variations in stress patterns. Two domains are evidenced at a regional scale, separated by the active Raikhot fault, the western boundary of the Nanga Parbat spur. West of this fault, a wrench-type stress field with σ1 axis oriented around N–S predominates in the Karakorum and in Kohistan. It predates Pliocene-Quaternary exhumation of Nanga Parbat and corresponds to the Miocene or earlier regional stress field related to Indian-Asian convergence. East of the Raikhot fault, compression parallel to the belt accounts for initiation of the Nanga Parbat anticlinorium after 5 Ma. It is followed by predominant post-2 Ma extension, both parallel to the belt and NNE–SSW oriented. Thus, in the N–W Himalayan syntaxis, multidirectional extension is juxtaposed on short timescales to shortening either parallel or perpendicular to the belt. Such juxtaposition could be characteristic of strain and stress partitioning during oblique convergence

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Section: Discussionmentioning

confidence: 99%

Stress field evolution in the northwest Himalayan syntaxis, northern Pakistan

et al. 2008

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“…There is a rapid drop to “background levels” after circa 470 Ma, falling further to zero by circa 1100 Ma, and a small cluster of ages at circa 1600 Ma (Figure 3a). Ar loss in older grains precludes accurate provenance analysis, but ages are consistent with known tectonothermal events affecting rocks of the Indian plate, including a Pre‐Cambrian metamorphic event, Cambro‐Ordovician and Carboniferous plutonism possibly associated with Pan‐African orogenesis and Neo‐Tethyan rifting, and Jurassic and Early Cretaceous thermal events [ Treloar et al , 1989b; Treloar and Rex , 1990; Gaetani and Garzanti , 1991; Smith et al , 1994; Garzanti et al , 1999; Treloar et al , 2000] (see section 2.2). Some contribution from the Kohistan arc might also be expected.…”

Section: Balakot Formationmentioning

confidence: 75%

“…In the footwall of the MMT, many of the Indian plate rocks attest to a polymetamorphic and deformational pre‐Himalayan history. Granulite facies metamorphism and migmatisation affected the Indian plate basement gneisses at circa 1850 Ma [ Treloar et al , 2000], reflected in the cooling ages of a variety of minerals [ Chamberlain et al , 1989; Zeitler et al , 1989; Treloar et al , 1989b; Treloar and Rex , 1990; Schneider et al , 1999] A mafic dyke intrusion event crosscuts the metamorphic fabric at circa 1600 Ma [ Treloar et al , 2000]. Dating of a series of granitoids suggests a period of magmatism, probably related to the Pan‐African orogeny, in the Cambro‐Ordovician, circa 400–500 Ma, with a cluster of ages at circa 470 Ma [ Le Fort et al , 1979; Zeitler et al , 1989; Chamberlain et al , 1989; Treloar et al , 1991, 2000; Foster et al , 1999; Lombardo et al , 2000].…”

Section: Geological Background Of the Himalayamentioning

confidence: 99%

A reinterpretation of the Balakot Formation: Implications for the tectonics of the NW Himalaya, Pakistan

et al. 2002

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[1] The Balakot Formation of the Himalayan foreland basin in Pakistan was originally described as a >8 km thick clastic red bed succession within which are stratigraphically intercalated four gray marl bands containing fossils dated at 55-50 Ma. On this basis, and the reported conformable contact with the underlying Paleocene Patala Formation, the Balakot Formation red beds were interpreted as tidal facies dated at 55-50 Ma, by >20 Myr the oldest foreland basin sediments eroded from the metamorphic orogen. However, our new detailed structural mapping shows the Balakot Formation to be in tectonic contact with the underlying Patala Formation, and the marl bands to be structurally intercalated with the red beds. Hence neither the nature of the Balakot Formation lower contact nor the intercalated marl bands can be used to date the red beds. Our Ar/Ar dating of 257 individual detrital white micas from the Balakot Formation red bed sandstones shows that the red bed succession must be younger than 37 Ma, and we thus conclude that the first exposed foreland basin continental sediments eroded from the metamorphic mountain belt were deposited after 37 Ma, at least 15 Myr later than previously believed. These new structural, stratigraphic, and isotopic data from the Balakot Formation provide new constraints to the early tectonic evolution of the mountain belt, result in reassessment of the facies and provenance of the Balakot Formation, and force reconsideration of models of orogenesis, basin evolution, and the timing and diachroneity of India-Asia collision that are based on the original documentation of the Balakot Formation.

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“…Rapidly evolving terranes and tectonic systems often yield a small range of ages for mineral geochronometers that have very different closure temperatures, including polygenetic Th-and U-bearing accessory minerals formed at or close to peak metamorphic conditions (e.g., Dallmeyer et al, 1986;Dokka et al, 1986;Goodwin and Renne, 1991;Baldwin et al, 1993Baldwin et al, , 2004Brown and Dallmeyer, 1996;Platt et al, 1998;Treloar et al, 2000;Di Vincenzo and Palmeri, 2001;Zeitler et al, 2001;de Jong, 2003;Štípská et al, 2004;Çelik et al, 2006;Schulmann et al, 2008;Pitra et al, 2010;Wilke et al, 2010;Charles et al, 2012;Cubley et al, 2013a,b;Daoudene et al, 2013). Tectonically exhumed terranes generally experienced rapid cooling, whereas exhumation by erosion record slow cooling (e.g., Dallmeyer et al, 1986;Dokka et al, 1986;Baldwin et al, 1993Baldwin et al, , 2004Brown and Dallmeyer, 1996;Platt et al, 1998;Charles et al, 2012;Cubley et al, 2013a,b;Daoudene et al, 2013;Scibiorski et al, 2015), unless erosion was forced by extreme exhumation and became the driving force, as exemplified by the eastern and western Himalayan syntaxes (e.g., Treloar et al, 2000;Zeitler et al, 2001).…”

Section: Tectonically-induced Coolingmentioning

confidence: 99%

Fast cooling following a Late Triassic metamorphic and magmatic pulse: implications for the tectonic evolution of the Korean collision belt

2015

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International audienceWe discuss the evolution of Korea in the context of a relatively short-lived, tectonically induced, magmatic and metamorphic pulse that affected large portions of the crust of the peninsula's southern part during the Late Triassic. Recent 40Ar/39Ar single grain laser step-heating dates imply a prolonged metamorphic recrystallization between 243 and 220 Ma, which occurred in distinct phases that were not coeval throughout the peninsula. We obtained identical plateau ages between 231.4 ± 0.8 and 228.9 ± 0.8 Ma (1σ; 85–95% 39Ar release) on single grains of detrital muscovite from Jurassic sandstones (Gimpo Group). A literature review shows that the ages of detrital muscovites are identical to: (1) concordant 40Ar/39Ar ages of biotite (228 Ma) and amphibole (230 Ma) in amphibolites of the Deokjeongri Gneiss Formation and the Weolhyeonri Complex, pointing to very rapid cooling of 100–150 °C/Ma, and (2) 231–229 Ma muscovite from the low-grade metamorphic mid-Paleozoic turbidites of the Taean Formation. The efficiency of cooling is further underlined by the near-coincidence of these 40Ar/39Ar ages with 243–229 Ma (average: 234.6 Ma) zircon U–Pb ages in the Gyeonggi Massif and the Hongseong belt, in the literature. It is argued that the Late Triassic magmatic and metamorphic pulse is superimposed on an earlier tectono-metamorphic event, possibly related to collision, indicated by: (1) ~ 243–237 Ma muscovite ages, or age components in age spectra, and (2) two generations of folds and associated tectonic foliations truncated by ~ 229.5-Ma-old syenites and earlier mafic dykes. The Late Triassic thermal pulse could have been the result of post-collisional delamination of the lower crust and uppermost mantle, and/or oceanic slab break-off, which is also suggested by almost coeval, widespread mantle-sourced Mg-rich potassic magmatism. Continuing ductile deformation is shown by mylonitization of Late Triassic magmatic rocks; an ~ 220 Ma muscovite age may be related to this

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Tectonics of the Nanga Parbat syntaxis and the western Himalaya: an introduction

Cited by 16 publications

References 24 publications

Stress field evolution in the northwest Himalayan syntaxis, northern Pakistan

Stress field evolution in the northwest Himalayan syntaxis, northern Pakistan

A reinterpretation of the Balakot Formation: Implications for the tectonics of the NW Himalaya, Pakistan

Fast cooling following a Late Triassic metamorphic and magmatic pulse: implications for the tectonic evolution of the Korean collision belt

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