Two contrasting eclogite types in the Himalayas: implications for the Himalayan orogeny

Lombardo, B.; Rolfo, Franco

doi:10.1016/s0264-3707(99)00026-5

Cited by 146 publications

(129 citation statements)

References 41 publications

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“…It has a well preserved sequence of strata, without intrusion, but the normal fault contact boundary with Paleoproterozoic granitic gneiss was found. High-pressure (HP) mafic granulites [21] or retrograde eclogite [22] were also found as lentoid in both the upper and lower units.…”

Section: Geological Settingmentioning

confidence: 99%

Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya, Tibet: Geochronology and implications

Liao

et al. 2008

Sci. China Ser. D-Earth Sci.

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Granitic gneisses have been widely found in crystalline rocks in theDinggye area of the Higher Himalaya (HHM) and the LhagoiKangri area of the North Himalaya (NHM), Tibet. In the HHM, the gneisses intruded in the granulite-amphibolite facies metamorphosed sedimentary rocks, known as Nyalam group. In the NHM, the gneisses intruded in the amphibolite facies metamorphosed ones, known as LhagoiKangri group. These granitic gneisses are peraluminous monzonitic granites in terms of their mineral assemblage, and are considered as being derived from metamorphosed sedimentary rocks by anatexis based on the transitional relationship of the gneisses with their migmatitized wall rocks. Zircons are similar in crystal shape and interior structure from both gneisses. Most of them are euhedral or subhedral elongated prism-shaped transparent crystals, with fine oscillatory zoning, showing the magmatic genesis. Some of them are short prism-shaped and with relict core inherited from magma source and oscillatory zoning mantle crystallized from magma. SHRIMP U-Pb dating of zicons shows that both the granitic gneisses in the HHM and NHM are Paleoproterozoic (1811.6±2.9 Ma and 1811.7±7.2 Ma, respectively). These ages are similar to those (1815 to 2120 Ma) from granitic gneiss which is widely distributed in the Lesser Himalaya (LHM). The ages of inherited zircons (>2493.9±7.0 Ma, 2095.8± 8.8 Ma, 1874±29 Ma) exhibit the possible presence of several thermal events in Paleoproterozoic. All of the ages suggest the same India basement beneath the different units in Himalaya area, and do not support the idea that the HHM and NHM are accretionary terranes in Pan-Africa orogenic event.The fact that the basement in HHM is as old as or even younger than LHM is inconsistent with the presently prevalent orogenic models such as either extrusion of low-viscosity mid-crust or orogenic channel.

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Section: Geological Settingmentioning

confidence: 99%

Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya, Tibet: Geochronology and implications

Liao

et al. 2008

Sci. China Ser. D-Earth Sci.

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“…Pressure -Temperature (P -T) estimates calculated for the Kaghan valley UHP eclogites are 2.7 to 3.2 GPa, and 760 °C to 790 °C (O'Brien et al, 2001;Kaneko et al, 2003;Rehman et al, 2007). To understand the collision tectonics and to decipher the regional metamorphic processes, geological field and analytical research works were carried out during the last two decades (e.g., Honegger et al, 1982;Greco et al, 1989;Papritz and Rey, 1989;Tonarini et al, 1993;Spencer et al, 1995;Lombardo and Rolfo, 2000;O'Brien et al, 2001;Guillot et al, 2003;Kaneko et al, 2003;Parish et al, 2006 etc.). Rehman et al (2007) estimated the thermobaric structure along the Kaghan valley transect.…”

Section: Introductionmentioning

confidence: 99%

Metamorphic history and tectonic evolution of the Himalayan UHP eclogites in Kaghan valley, Pakistan

Rehman

Yamamoto

Khalil³

et al. 2008

Journal of Mineralogical and Petrological Sciences

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Eclogites of the Kaghan valley, Pakistan Himalaya were investigated petrographically and geochemically. Based on petrography, geochemistry and mineral compositions, metamorphic history and a reasonable tectonic model are proposed. Eclogites exposed in the Kaghan valley are classified into two groups. Group I eclogites appear as massive and Group II are lens -type. Group I eclogites have a mineral assemblage of garnet, omphacitic clinopyroxene, quartz, symplectite with rare epidote and phengite. Accessory minerals include abundant zircon, rutile, ilmenite, and rare apatite. Group II eclogites have a mineral assemblage of garnet, omphacitic clinopyroxene, phengite, quartz/coesite, epidote, and symplectite. In accessory minerals rutile and ilmenite are common while zircon and apatite are rare. Different types of protolith are proposed for these eclogites. Group I eclogites have higher FeO and TiO 2 contents and trace element contents, and seem to be derived from gabbroic protolith. Group II eclogites have lower FeO and TiO 2 and trace element contents and were derived from basalts. Pressure -temperature -time path was constructed for the Kaghan valley eclogites using various mineral assemblages along with textural relationship and inclusions study. At least three distinct metamorphic stages were identified. The first stage is the prograde garnet growth stage deduced from the inclusion paragenesis in garnet core. The second stage records the ultrahigh -pressure metamorphic stage deduced from the presence of coesite inclusions in omphacitic clinopyroxene. The third stage is the decompression stage and is deduced from the quartz -albite -amphibole symplectite portions. These petrological and geochemical results combined with isotopic ages reported elsewhere indicate that basalts and associated gabbroic dikes were emplaced at about 267 Ma when the Indian plate was moving northward and passing above an unknown hot spot. The closure of the Tethys and initiation of collision of the Indian plate with the Kohistan -Ladakh Island Arc is reported from 65 -50 Ma. After that the leading -edge of the Indian plate underwent eclogite facies metamorphism at 49 Ma and when it reached to depths of about 100 km, the ultrahigh -pressure metamorphic event took place at 46 Ma.

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“…Makalu in the north Arun Valley, in the Kharta region of Tibet (Lombardo and Rolfo 2000), and the Makalu-Everest region of the Arun River valley in east Nepal (Parkinson and Kohn 2002). These eclogites are different from those of Pakistan and India, as they did not reach the ultra-high-pressure metamorphism and they are strongly overprinted by subsequent metamorphism, leaving meager evidence for eclogitization.…”

Section: Subduction Metamorphism and Eclogitesmentioning

confidence: 99%

“…These conditions were followed by isothermal decompression down to a pressure of about 0.3 GPa. The peak metamorphism occurred around 30 Ma, whereas their isothermic decompression took place from 20 to 12 Ma (Lombardo and Rolfo 2000;Liu et al 2007;Groppo et al 2007;Kali et al 2010). Corrie et al (2010) used garnet geochronology to measure the timing of eclogitization in the Arun Valley, and they obtained an age of 20.7 ± 0.4 Ma, significantly younger than ultra-high-pressure eclogites from the western Himalaya.…”

Section: Subduction Metamorphism and Eclogitesmentioning

confidence: 99%

Introduction to Higher Himalaya

Dhital

2015

Geology of the Nepal Himalaya

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Two contrasting eclogite types in the Himalayas: implications for the Himalayan orogeny

Cited by 146 publications

References 41 publications

Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya, Tibet: Geochronology and implications

Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya, Tibet: Geochronology and implications

Metamorphic history and tectonic evolution of the Himalayan UHP eclogites in Kaghan valley, Pakistan

Introduction to Higher Himalaya

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