Talc-, Magnesite- and Ti-Clinohumite-Bearing Ultrahigh-Pressure Meta-Mafic and Ultramafic Complex in the Dabie Mountains, China

Zhang, R. Y.; Liou, J. G.; Cong, Bin

doi:10.1093/petrology/36.4.1011

Cited by 184 publications

(119 citation statements)

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“…The complex consists of banded felsic and mafic eclogites that contain thin layers of garnet-bearing cumulate ultramafic rock. Detailed petrological and geochemical studies have been made by Zhang et al (1995). All the eclogite samples in this study are light in colour and rich in kyanite, the same as type (3) of ''foliated kyanite-rich, talc-bearing coesite eclogite'' described by Zhang et al (1995) who distinguished six types of eclogites in Bixiling.…”

Section: Petrology and Fluid Inclusionsmentioning

confidence: 65%

“…Detailed petrological and geochemical studies have been made by Zhang et al (1995). All the eclogite samples in this study are light in colour and rich in kyanite, the same as type (3) of ''foliated kyanite-rich, talc-bearing coesite eclogite'' described by Zhang et al (1995) who distinguished six types of eclogites in Bixiling. The light-coloured eclogites contain garnet, omphacite, quartz, kyanite and phengite, along with minor rutile (Fig.…”

Section: Petrology and Fluid Inclusionsmentioning

confidence: 65%

“…The minerals show little alteration, deformation or weathering. Zhang et al (1995) concluded that the ultramafic metamorphic assemblages formed at 700-800°C and 47-67 kbar, following initial emplacement at normal crustal levels and subsequent subduction to great depths (>100 km) during the collision of the Sino-Korean and Yangtze cratons. T (°C) at 30 kbar.…”

Section: Petrology and Fluid Inclusionsmentioning

confidence: 99%

“…1) (Xu et al, 1992;Zhang et al, 1995;Ye et al, 2000Ye et al, , 2001Ye et al, , 2002Xu et al, 2003) and, as a consequence, have become the focus of intense geological research on the characteristics of UHP metamorphism (Li et al, 1993;Okay et al, 1993;Hacker and Wang, 1995;Liu et al, 1995;Cao and Zhu, 1996;Chavagnac and Jahn, 1996;Hacker et al, 1998;Yang and Jian, 1998;Cong and Wang, 1999;Yang et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Metamorphic temperatures and pressures of ca. 600-1140°C and 18-67 kbar were estimated (Okay, 1993;Zheng, 1993a,b;Zhang et al, 1995;Xiao et al, 2000). Extremely deep burial is demonstrated by ubiquitous coesite and local diamond (Xu et al, 1992(Xu et al, , 2003Ye et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Paleozoic ages and excess 40Ar in garnets from the Bixiling eclogite in Dabieshan, China: New insights from 40Ar/39Ar dating by stepwise crushing

Qiu

Wijbrans

2006

Geochimica et Cosmochimica Acta

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The 40 Ar/ 39 Ar stepwise crushing technique is applied for the first time to date garnet from ultra-high-pressure metamorphic (UHPM) eclogites. Three garnet samples from the Bixiling eclogites analyzed by 40 Ar/ 39 Ar stepwise crushing yield regular, predictable age spectra, and a clear separation between excess 40 Ar and concordant plateau and isochron ages. All three age spectra begin with high apparent ages followed by step by step decreasing ages, and finally age plateaux with apparent ages in the range from 427 ± 20 to 444 ± 10 Ma. The data points constituting the age plateaux yield excellent isochrons with radiogenic intercept ages ranging from 448 ± 34 to 459 ± 58 Ma, corresponding to initial 40 Ar/ 36 Ar ratios from 292.1 ± 4.5 to 294.5 ± 6.7, statistically indistinguishable from the modern air. The high initial ages are interpreted to derive from secondary fluid inclusions containing excess 40 Ar, whereas the plateau ages are attributed to gas from small primary fluid inclusions without significant excess 40 Ar. The plateau ages are interpreted to approximate the time of garnet growth during initial UHPM metamorphism. Phengite analyzed by laser stepwise heating yielded a complicated two-saddle age spectrum with a scattered isochron corresponding to age of 463 ± 116 Ma and initial 40 Ar/ 36 Ar ratio of 1843 ± 1740 indicative of the presence of extraneous 40 Ar within phengite. These concordant isochron ages measured on minerals diagnostic of eclogite grade metamorphism strongly suggest that Dabie UHPM eclogites were first formed in the early Paleozoic, during the same event that caused the Qinling-Northern Qaidam Basin-Altyn Tagh eclogites.

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Section: Petrology and Fluid Inclusionsmentioning

confidence: 65%

Section: Petrology and Fluid Inclusionsmentioning

confidence: 65%

Section: Petrology and Fluid Inclusionsmentioning

confidence: 99%