Metamorphic Characteristics and Tectonic Implications of the Kadui Blueschist in the Central Yarlung Zangbo Suture Zone, Southern Tibet

Sun, Guang-Ming; Li, Xuping; Duan, Wen-Yong; Chen, Shuang; Wang, Zeli; Ling, Zhao; Feng, Qingda

doi:10.1007/s12583-018-0854-9

Cited by 16 publications

(2 citation statements)

References 78 publications

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“…The garnet clinopyroxenite samples show relative depletion of HFSEs (e.g., Nb, Zr, and Ti) and relative enrichment of large-ion lithophile elements (e.g., Rb, Sr, Ba, and Pb), which are typical geochemical features of subduction magmatism [63][64][65][66][67][68]. Most subduction-related UHP peridotites are interpreted to be from the lithospheric mantle wedge, above the pre-subduction zone [69,70], which typically exhibits enrichments of oceanic plate-derived elements [68,[71][72][73][74][75]. According to field observations, and petrological and geochemical data, the Hujialin garnet clinopyroxenites are cumulates formed by melt crystallization in the mantle wedge of an ancient subduction zone.…”

Section: Protolith and Structural Modelmentioning

confidence: 99%

Metamorphic Evolution of Garnet-Bearing Ultramafic Rocks in the Hujialin Area, Sulu Ultrahigh-Pressure Orogenic Belt, Eastern China

Wang

Zhang

et al. 2020

Minerals

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The Rizhao Hujialin area is located in the central Sulu ultrahigh-pressure orogenic belt, where garnet clinopyroxenite is exposed in the upper part of an ultramafic rock complex and serpentinized dunite is exposed in its lower part. Based on textural criteria, the garnet clinopyroxenites were divided into three types: Equigranular garnet, porphyroclastic garnet, and megacrystic garnet pyroxenites. The garnet clinopyroxenites have convex-upward chondrite-normalized rare earth element patterns, large positive Pb anomalies, and depletion of high-field-strength elements (e.g., Nb, Zr, and Ti), suggesting a mantle source protolith overprinted by fluid metasomatism. Petrographic, mineral chemistry, phase equilibrium modeling, and zircon U–Pb geochronology data show that the evolutionary stages of the Hujialin garnet clinopyroxenites were as follows: Stage I: formation of the magmatic protoliths; stage II: formation of megacrystic garnet pyroxenite accompanying subduction; stage III: formation of porphyroclastic or equigranular garnet clinopyroxenite with a mineral assemblage of garnet + clinopyroxene + ilmenite + humite accompanying initial exhumation at ~215.0 ± 5.7 Ma; stage IV = progressive cooling and decompression associated with the crystallization of water-bearing minerals such as clinochlore and pargasite at 206 Ma; and Stage V = late epidote amphibolite-facies retrograde metamorphism producing a mineral assemblage of garnet + clinopyroxene + amphibole + chlorite + epidote + ilmenite at ~180–174 Ma associated with fluid activity in shear–tensional fractures and/or pores. The P-T conditions of the peak metamorphism were estimated at 4.5 ± 0.5 GPa and 800 ± 50 °C. Retrograde metamorphism recorded conditions of 1.0 GPa and 710 ± 30 °C during the exhumation and cooling process. The mineral transformation from early high-Al clinopyroxene to garnet and to late diopside records the general metamorphic evolution during subduction and exhumation, respectively. One zircon U–Pb analysis presents the Palaeoproterozoic age of 1817 ± 40 Ma, which is coeval with widespread magmatic and metamorphic events in the North China Craton.

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Section: Protolith and Structural Modelmentioning

confidence: 99%

Metamorphic Evolution of Garnet-Bearing Ultramafic Rocks in the Hujialin Area, Sulu Ultrahigh-Pressure Orogenic Belt, Eastern China

Wang

Zhang

et al. 2020

Minerals

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“…In other areas of the LSN, also only single P-T conditions were reported (Fassmer et al, 2017;Klonowska et al, 2016;Majka et al, 2014a). The lack of a determined P-T path in a wider terrane would block the establishment of the comprehensive geodynamic history (e.g., Rahimi and Massonne, 2020;Zhang et al, 2019;Sun et al, 2018). In order to constrain a more precise P-T evolution for a gneiss of the LSN in the Handöl area and to find further evidence for UHP, we applied phasediagram modeling using PERPLE_X.…”

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confidence: 99%

Pressure-Temperature Evolution of a Mylonitic Gneiss from the Lower Seve Nappe in the Handöl Area, Central Sweden

Massonne

Yuan

2021

J. Earth Sci.

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Ultrahigh-pressure metamorphism has recently been reported from various crustal rocks in the Seve Nappe Complex (SNC) in which microdiamonds were found. However, in gneiss from the Lower Seve Nappe (LSN), neither any direct petrographic indication for UHP was reported nor the metamorphic evolution was well constrained. We studied a mylonitic gneiss from the Handöl area of the LSN and applied phase-diagram modeling and Ti-in-biotite thermometry. Based on the compositions of garnet and biotite and observed mineral assemblages, a path was reconstructed passing through about 8 kbar and 730 °C at prograde metamorphism. Peak-pressure and initial retrograde stages occurred at 9.0-10.2 kbar at 745-775 °C, and 7-9 kbar at <750 °C, respectively. No ultrahigh-pressure evidence was recognized compatible with medium-pressure metamorphism deduced in earlier studies of gneiss from the SNC. As higher peak pressures were reported recently for metamorphic rocks of the LSN, a possible interpretation is that slices or erased blocks were subducted, metamorphosed at different depths, and exhumed in a subduction channel. However, the dominant gneiss of the SNC experienced only a medium-pressure metamorphism in the upper part of the downgoing Baltica Plate. Rocks from different depth levels were brought together in an exhumation channel located between Baltica and the overlying plate.

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A H2O-in-zircon perspective on the heterogeneous water content of crust-derived magmas in southern Tibet

Meng

Xia

et al. 2021

Sci. China Earth Sci.

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Metamorphic Characteristics and Tectonic Implications of the Kadui Blueschist in the Central Yarlung Zangbo Suture Zone, Southern Tibet

Cited by 16 publications

References 78 publications

Metamorphic Evolution of Garnet-Bearing Ultramafic Rocks in the Hujialin Area, Sulu Ultrahigh-Pressure Orogenic Belt, Eastern China

Metamorphic Evolution of Garnet-Bearing Ultramafic Rocks in the Hujialin Area, Sulu Ultrahigh-Pressure Orogenic Belt, Eastern China

Pressure-Temperature Evolution of a Mylonitic Gneiss from the Lower Seve Nappe in the Handöl Area, Central Sweden

A H2O-in-zircon perspective on the heterogeneous water content of crust-derived magmas in southern Tibet

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