Sapphirine-bearing high pressure mafic granulite and its implications in the south Altyn Tagh

2005 ◽  
Vol 50 (3) ◽  
pp. 265
Author(s):  
Jianxin ZHANG
Keyword(s):  
High Pressure ◽  
Mafic Granulite ◽  
The South ◽  
Altyn Tagh

Mineral ages and P-T conditions of Late Paleozoic high-pressure eclogite and provenance of melange sediments from Atbashi in the south Tianshan orogen of Kyrgyzstan

2010 ◽  
Vol 310 (9) ◽  
pp. 916-950 ◽  
Author(s):  
E. Hegner ◽  
R. Klemd ◽  
A. Kroner ◽  
M. Corsini ◽  
D. V. Alexeiev ◽  
...  
Keyword(s):  
High Pressure ◽  
Late Paleozoic ◽  
The South ◽  
South Tianshan

Petrological, geochronological, and geochemical potential accounting for continental subduction and exhumation: A case study of felsic granulites from South Altyn Tagh, northwestern China

2020 ◽  
Vol 132 (11-12) ◽  
pp. 2611-2630
Author(s):  
Yunshuai Li ◽  
Jianxin Zhang ◽  
Shengyao Yu ◽  
Yanguang Li ◽  
Hu Guo ◽  
...  
Keyword(s):  
High Pressure ◽  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Granitic Rocks ◽  
Geodynamic Evolution ◽  
Altyn Tagh ◽  
Rare Earth Element Distribution ◽  
Ultrahigh Temperature

Abstract Deciphering the formation and geodynamic evolution of high-pressure (HP) granulites in a collisional orogeny can provide crucial constraints on the geodynamic evolution of subduction-exhumation. To fully exploit the geodynamic potential of metamorphic rocks, it is necessary to constrain the metamorphic ages, although it is difficult to link zircon and monazite ages to metamorphic evolution. A good case study for understanding these geodynamic processes is felsic granulites in the Bashiwake area, South Altyn Tagh. Petrographic observations suggest that the studied felsic granulites have suffered multi-stage metamorphism, and the distinct metamorphic events were documented by compositional zoning and high Y + heavy rare earth element (HREE) concentrations in the large garnet porphyroblast. Zircon U-Pb dating yielded two major age clusters: one age cluster at ca. 900 Ma represents the age of the protolith for the felsic granulite, and another age cluster at ca. 500 Ma represents the post-UHT (ultrahigh temperature) stage based on the rare earth element distribution coefficients between zircon and garnet. Meanwhile, in situ monazites U-Pb dating yielded a weighted mean 206Pb/238U age of 482 ± 3.5 Ma, and the monazite U-Pb age was interpreted to be in agreement with the metamorphic zircon rims data, which together with zircon recorded the cooling time after the UHT stage. Whole-rock major and trace elements as well as Sr-Nd isotopes suggest that the protolith of the felsic granulite derived from partial melting of ancient crustal materials with the addition of mantle materials. Integrating these results along with previous studies, we propose that the felsic granulites metamorphosed from the Neoproterozoic granitic rocks, and the granitic rocks with associated mafic-ultramafic rocks suffered a common high-pressure–ultrahigh temperature (HP-UHT) metamorphism and subsequent granulite-facies metamorphism. A tentative model of subduction-relamination was proposed for the geodynamic evolution of the Bashiwake unit, South Altyn Tagh.

Petrogenesis of mafic granulite in South Altyn Tagh, NW China: Constraints from petrology, zircon U–Pb chronology, and geochemistry

2019 ◽  
Vol 55 (2) ◽  
pp. 1431-1449 ◽  
Author(s):  
Yunshuai Li ◽  
Jianxin Zhang ◽  
Yanguang Li ◽  
Khan M.G. Mostofa ◽  
Shengyao Yu ◽  
...  
Keyword(s):  
Mafic Granulite ◽  
Nw China ◽  
Altyn Tagh

scholarly journals Quartz paramorphs after former stishovite in UHP eclogite from the South Altyn Tagh, Western China and its Significance

2019 ◽  
Vol 93 (S2) ◽  
pp. 18-18
Author(s):  
Liang LIU ◽  
Danling CHEN ◽  
Junfeng ZHANG ◽  
Lei KANG ◽  
Xiaoying LIAO ◽  
...  
Keyword(s):  
Western China ◽  
The South ◽  
Altyn Tagh

Metamorphic evolution of Raspas complex (Ecuador) and its relation with a J-K belt of melanges in NW of the South American plate.

2020 ◽  
Author(s):  
Mayda Arrieta-Prieto ◽  
Carlos Zuluaga-Castrillón ◽  
Oscar Castellanos-Alarcón ◽  
Carlos Ríos-Reyes
Keyword(s):  
High Pressure ◽  
Subduction Zones ◽  
Mineral Chemistry ◽  
White Mica ◽  
Petrographic Analysis ◽  
South American ◽  
The South ◽  
South American Plate ◽  
Subduction Channel ◽  
Southern Ecuador

<p>High-pressure complexes along the Earth's surface provide evidence of the processes involved in both the crystallization of rocks in the subduction channel and its exhumation. Such processes are key to understand the dynamics and evolution of subduction zones and to try to reconstruct P-T trajectories for these complexes.</p><p>Previous studies on the Raspas complex (southern Ecuador) agree to state that it is composed of metamorphic rocks, mainly blueschists and eclogites, containing the mineral assemblage: glaucophane + garnet + epidote + omphacite + white mica + rutile ± quartz ± apatite ± pyrite ± calcite; which stabilized in metamorphic conditions of high pressure and low temperature. Additionally, the Raspas Complex has been genetically related to accretion and subduction processes of seamounts, which occurred in South America during the Late Jurassic - Early Cretaceous interval; and the exhumation of the complex was related to subduction channels. However, the evidence presented in the existing literature makes little emphasis on the reconstruction of thermobarometric models for the rocks of this complex.</p><p>By combining petrographic observations, whole-rock chemistry, and mineral chemistry in this work; it was possible to determine that pressure values of 10 ± 3 Kbar and temperature values of 630 ± 30 ° C, (obtained by simulations with THERMOCALC®) correspond to an event of retrograde metamorphism, suffered by the complex during its exhumation. This theory is complemented by the specific textures (that suggest this retrograde process) observed during petrographic analysis, such as amphibole replacing pyroxene, garnet chloritization, plagioclase crystallization and rutile replacement by titanite.</p><p>The results obtained, together with the thermobarometry data published for the Arquía complex in Colombia, allow us to establish a P-T trajectory, that may suggest a genetic relationship between these two complexes as a result of the tectonic processes associated with an active subduction margin that affected the NW margin of the South American plate at the end of the Jurassic.</p><p> </p>

Sign in / Sign up

Export Citation Format

Share Document