Contribution of crustal anatexis to the tectonic evolution of Indian crust beneath southern Tibet

King, Jess; Harris, Nigel; Argles, Tom; Parrish, Randall R.; Zhang, Hongfei

doi:10.1130/b30085.1

Cited by 163 publications

(107 citation statements)

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“…Previous studies on the timing of crustal anatexis in the Himalayan orogenic belt indicated that leucogranites formed at 27-10 Ma in the NHGD and the HHCS are typical S-type granites, derived from muscovite dehydration melting of metapelites and characterized by high initial 87 Sr/ 86 Sr ratios of 0.7300-0.7800 and low  Nd from 10 to 15 [1][2][3][4][5][6][7]16,46,47]. Experimental results [6,7], theoretic calculations [22,23] and field investigations [4,16,18] all suggest that fertile metapelites could undergo progressive partial melting with variations in temperature, pressure, and water content, which leads to the formation of granites with different geochemical characteristics in major and trace element as well as in isotope (e.g.…”

Section: Source Rock Of the Paiku Composite Leucogranitementioning

confidence: 99%

“…Granites, migmatites, and high-grade metamorphic rocks are important components within these two belts and record distinct types of metamorphism and partial melting reactions of middle-lower crustal materials in response to the tectonic evolution of the Himalayan orogen [1,4,8,13,14,16,[26][27][28][29]. NHGD within the Tethyan Himalaya consists of a series of semi-continuous oval shape gneiss dome.…”

Section: Geological Setting and Sample Descriptionsmentioning

confidence: 99%

“…All these rock units are separated by ductile detachment fault. Except for the Kangmar Dome, all granites within the NHGD are younger than ~44 Ma [3,4,8,12,13,16,19,26,30]; whereas the granites within the HHCS formed at 37-10 Ma and are characterized by apparently lower melt temperature [3].…”

Section: Geological Setting and Sample Descriptionsmentioning

confidence: 99%

“…These anatectic episodes include (1) dehydration melting of a source consisting dominantly of amphibolite with subordinate pelitic gneiss at thickened crustal conditions [8][9][10][11][12][13][14]. These melting events are represented by older than 35 Ma peraluminous granitoids with relatively high Na/K and Sr/Y ratios; (2) fluid-present melting of metapelite since ~38 Ma to produce granitic melts with high CaO and Sr contents and low Rb/Sr ratios [15][16][17][18]; and (3) late Eocene to early Oligocene anatexis recorded in syn-collision leucogranites and migmatites in the Gyirong area and the Mabja Gneiss Dome [19][20][21]. A large number of studies have demonstrated that metapelites are fertile and could undergo progressive partial melting with variations in temperature, pressure, and water content, which leads to the formation of granites with different geochemical characteristics in major and trace element as well as in isotope (e.g.…”

mentioning

confidence: 99%

“…A large number of studies have demonstrated that metapelites are fertile and could undergo progressive partial melting with variations in temperature, pressure, and water content, which leads to the formation of granites with different geochemical characteristics in major and trace element as well as in isotope (e.g. Sr, Nd) geochemistry [4,6,7,16,18,22,23]. Therefore, these granites provide an important probe to investigate how the middle-lower crustal rocks respond to the tectonic evolution of orogenic belts.…”

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confidence: 99%

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Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet

et al. 2013

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The Paiku composite leucogranitic pluton in the Malashan gneiss dome within the Tethyan Himalaya consists of tourmaline leucogranite, two-mica granite and garnet-bearing leucogranite. Zircon U-Pb dating yields that (1) tourmaline leucogranite formed at 28.2±0.5 Ma and its source rock experienced simultaneous metamorphism and anatexis at 33.6±0.6 Ma; (2) two-mica granite formed at 19.8±0.5 Ma; (3) both types of leucogranite contain inherited zircon grains with an age peak at ~480 Ma. These leucogranites show distinct geochemistry in major and trace elements as well as in Sr-Nd-Hf isotope compositions. As compared to the two-mica granites, the tourmaline ones have higher initial Sr and zircon Hf isotope compositions, indicating that they were derived from different source rocks combined with different melting reactions. Combined with available literature data, it is suggested that anatexis at ~35 Ma along the Himalayan orogenic belt might have triggered the initial movement of the Southern Tibetan Detachment System (STDS), and led to the tectonic transition from compressive shortening to extension. Such a tectonic transition could be a dominant factor that initiates large scale decompressional melting of fertile high-grade metapelites along the Himalayan orogenic belt. Crustal anatexis at ~28 Ma and ~20 Ma represent large-scale melting reactions associated with the movement of the STDS.Himalayan orogenic belt, Northern Himalayan Gneiss Domes, leucogranite, crustal anatexis, tectonic transition Citation:Gao L E, Zeng L S, Hou K J, et al. Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet.

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Section: Source Rock Of the Paiku Composite Leucogranitementioning

confidence: 99%

Section: Geological Setting and Sample Descriptionsmentioning

confidence: 99%

Section: Geological Setting and Sample Descriptionsmentioning

confidence: 99%

mentioning

confidence: 99%

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Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet

et al. 2013

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Semibrittle deformation and partial melting of perthitic K‐feldspar: An experimental study

et al. 2014

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To investigate the relationships between deformation, cracking, and partial melting in the lower continental crust, axial compression and hydrostatic experiments were performed on K-feldspar single crystals at temperatures of 700°and 900°C and confining pressures between 0.75 and 1.5 GPa. Sample deformation was carried out at a constant strain rate of~10 À6 s À1 . The samples deformed at 700°C show typical brittle behavior with formation of conjugate fractures and peak stresses that increase with confining pressure. Samples deformed at 900°C show formation of shear fractures, peak stresses below the Goetze criterion, and inverse confining pressure dependence of peak stress, indicating that along the fractures deformation was not dominantly friction controlled. Microstructural and chemical analyses reveal the presence of melt (<6 vol %) of inhomogeneous composition along the shear zones and chemical compositional changes of gouge fragments. In a hydrostatic experiment performed at 900°C, no melt and no compositional changes were observed. These observations indicate that deformation of K-feldspars at high pressures and temperatures is controlled by the simultaneous formation of brittle fractures and melt. The formation of melt is strongly accelerated and kinetically favored by cracking, as demonstrated by the absence of melting in the hydrostatic experiments. However, the melt along fractures does not dramatically weaken the samples, as the melt domains remain isolated during deformation. The fine-grained gouge fragments formed along the fracture systems undergo chemical homogenization. The dominant deformation mechanism in the gouge is likely to be melt-enhanced diffusion creep, which may also assist the chemical homogenization process.

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Hot Versus Cold Orogenic Behavior: Comparing the Araçuaí‐West Congo and the Caledonian Orogens

2017

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Observations and modeling show that temperature controls crustal rheology and therefore also the orogenic evolution of continent‐continent collision zones and the associated tectonic style. In order to explore the effect of temperature in a natural environment, we compare eroded sections through the unusually cold lower Paleozoic North Atlantic Caledonian (Scandian) collision zone and the very hot Brasiliano/Pan‐African Araçuaí‐West Congo orogen. A cold and stiff subducting Caledonian continental margin was able to subduct as a rather coherent unit to ultrahigh‐pressure conditions, twice as deep as the Pan‐African/Brasiliano crust that was quickly heated and softened and got involved in partial melting. Furthermore, the Caledonian collision developed large coherent thrust sheets that were transported hundreds of kilometers toward the foreland. This was never achieved in the hot Araçuaí‐West Congo orogen, where much of the tectonic stress was absorbed by the partially molten central part of the orogen through magmatic state deformation. Major mylonite zones (thrusts) such as those seen in the Caledonides are therefore less common in the Araçuaí‐West Congo orogen. Further, the deep continental subduction in the Caledonides developed a strongly asymmetric collision zone, with rapid variations in pressure and temperature. In contrast, the Araçuaí‐West Congo orogen soon developed into a more symmetric geometry due to its easily flowing hot crust, with a relatively flat base and a corresponding plateau in its upper part. Deformation of the cold Caledonian crust was controlled by plate‐tectonic stress, while gravitational forces more strongly influenced the hot Brasiliano/Pan‐African example.

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Contribution of crustal anatexis to the tectonic evolution of Indian crust beneath southern Tibet

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Cited by 163 publications

References 88 publications

Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet

Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet

Semibrittle deformation and partial melting of perthitic K‐feldspar: An experimental study

Hot Versus Cold Orogenic Behavior: Comparing the Araçuaí‐West Congo and the Caledonian Orogens

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