The mineralogy, petrology, metamorphic PTDt trajectory and exhumation mechanism of blueschists, south Tianshan, northwestern China

Gao, Jun; He, Guojian; Mao-song, LI; Xiao, Xia; Tang, Ya‐Bin; Wang, Jun; Min, Zhao

doi:10.1016/0040-1951(95)00026-6

Cited by 169 publications

(140 citation statements)

References 23 publications

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“…At the Kulehu and Serikeya localities (Fig. 1B), N-MORB-type tholeiite and E-MORB-like alkali basalt were interpreted to be derived from mantle sources with the involvement of sea-floor sediments and the subcontinental lithosphere Tang et al, 1995b;Long et al 2006;Ma et al 2006a). The ophiolitic rocks in the Yushugou and Tonghuashan mélanges (Fig.…”

Section: Lateral Correlations Of the Ophiolitic Mélanges In The Southmentioning

confidence: 99%

“…This belt consists of greenschist-, blueschist-and eclogite-facies rocks, which were probably transformed from sea-floor deposits and basaltic rocks (Gao et al, , 1999Ai et al, 2006). Isotopic ages of 415-343 Ma (phengite 40 Ar/ 39 Ar plateau and Sm-Nd isochron) were obtained for eclogite and blueschist (Dobretsov et al, 1987;Xiao et al, 1992;Gao et al, 1995bGao et al, , 2000Gao et al, , 2006Gao and Klemd, 2003), and the peak HP metamorphism was considered to have occurred at ~345 Ma (Gao and Klemd, 2003;Klemd et al, 2005). In addition, eclogites and blueschists yielded younger ages of 331~302 Ma (recrystallized phengite 40 Ar/ 39 Ar plateau and Rb-Sr isochron) that were regarded as reflecting the timing of retrograde metamorphism during exhumation of the HP metamorphic rocks (Gao and Klemd, 2003;Stupakov et al, 2004;Klemd et al, 2005;Simonov et al, 2008;Wang et al, 2010).…”

Section: Hp Metamorphic Complex and Related Ophiolitic Rocksmentioning

confidence: 99%

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Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)

et al. 2011

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of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China). Tectonophysics, Elsevier, 2011, 497 (1-4) ABSTRACTIn the southern Chinese Tianshan, the southernmost part of the Central Asian Orogenic Belt (CAOB), widespread ophiolitic mélanges form distinct tectonic units that are crucial for understanding the formation of the CAOB. However, the polarity of oceanic subduction and age of orogeny are still in controversy. In order to better understand these geological problems, a comprehensive study was conducted on the

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Section: Lateral Correlations Of the Ophiolitic Mélanges In The Southmentioning

confidence: 99%

Section: Hp Metamorphic Complex and Related Ophiolitic Rocksmentioning

confidence: 99%

Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)

et al. 2011

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“…1). The Tian Shan stretches from NW China to Kirghizia and Tajikistan and is situated along the southwestern margin of the Central Asia Orogenic Belt (Gao et al, 1995;Sengör et al, 1993;Volkova and Budanov, 1999). In the Chinese part of the South Tian Shan, the HP/LT belt extends along the Southern Central Tian Shan suture for at least 200 km, separating the Tarim craton to the south and the Yili -central Tian Shan block to the north.…”

Section: Geology and Sample Descriptionmentioning

confidence: 99%

“…The HP/LT sequences occur discontinuously within a Paleozoic accretionary wedge (Gao et al, 1995(Gao et al, , 1998) and predominantly comprise eclogite-, blueschist-, and greenschist-facies metasedimentary rocks. Subordinate metavolcanic rocks, ultramafic slices and lenses of Silurian marble occur as exotic blocks and point towards an origin as tectonic mélange (Gao et al, 1999;van der Straaten et al, 2008).…”

Section: Geology and Sample Descriptionmentioning

confidence: 99%

Tracing the effects of high-pressure metasomatic fluids and seawater alteration in blueschist-facies overprinted eclogites: Implications for subduction channel processes

Straaten¹,

Halama²,

John³

et al. 2012

Chemical Geology

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Nils, Tracing the effects of high-pressure metasomatic fluids and seawater alteration in blueschist-facies overprinted eclogites: Implications for subduction channel processes, Chemical Geology (2011Geology ( ), doi: 10.1016Geology ( /j.chemgeo.2011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

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“…Some deepseated metamorphic slabs were exhumated to shallow crustal levels along suture zones, e.g. the blueschist slab at Kumux in the northern margin of the southern Tianshan ( Gao et al, 1995), the eclogite blocks in the Hark Mountains of the southwestern Tianshan ( Gao et al, 1997 andGao et al, 1999), and the granulitic blocks in the northern margin of the southern Tianshan ( Shu et al, 1996 andWang et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Geological, geochronological and geochemical features of granulites in the Eastern Tianshan, NW China

Shu

Charvet

et al. 2004

Journal of Asian Earth Sciences

120

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This paper reports new results on the petrology, geochronology and geochemistry of two kmscale high-pressure granulite exposures, namely the Weiya and the Yushugou granulites, that occur in the central and southern Tianshan Paleozoic sub-belts, respectively. Petrological and geochemical results suggest that the Weiya and the Yushugou granulites are different in both the rock types and geological structures. The protolith of the Weiya granulite is basic to intermediate rocks, and that of the Yushugou granulite is basic rocks; the former is distributed as fault-bounded blocks within the Precambrian schist-gneiss, and the latter occurs as thrust slabs in the allochthonous ophiolitic mélange. Observation of deformation structures provides some evidence for two-phase ductile deformation of the Tianshan granulites, characterized by deformed garnet-pyroxene and deformed feldspar-quartz microstructures, corresponding to rheological conditions of the lower crustal level and of the middle crustal level, respectively. The deformation structures also indicate that the Weiya granulite was involved in the late stage retrograde metamorphism forming new amphibole, following a thrusting movement toward the north and ductile deformation of feldspar-quartz grains. The Yushugou granulite underwent strong ductile shearing during the Silurian-Devonian interval. Three stages of metamorphism are recorded by mineral assemblages of the Weiya granulite: M 1 =Pl+Qtz+Bt, M 2 =Cpx+Grt+Pl+Qtz+Atp±Opx, and M 3 =Amp+Ep+Pl+Bt+Qtz, in contrast to a two-stage metamorphic history of the Yushugou granulite: M 1 =Cpx+Grt+Pl±Hyp, M 2 =Amp+Pl+Qtz±Bt. The P-T condition estimates suggest that the Weiya granulite was formed between 910-1025 °C and 1.08-1.12 GPa, and underwent retrograde metamorphism at 650-670 °C, while the peak metamorphism of the Yushugou granulite took place between 800-870 °C and 0.88-1.13 GPa. Geochemical characteristics (major, REE and incompatible elements) of the Weiya and Yushugou granulites indicate that their protoliths were formed in a volcanic arc setting, implying that a late Precambrian active continental margin may have existed in the study area. The Sm-Nd isochron dating for the Weiya granulite suggests that the peak metamorphism occurred at 538±24 Ma, which was likely related to the ancient plate subduction. The 40 Ar/ 39 Ar dating on amphibole grains separated from the Weiya granulite yielded a plateau age of 432±1 Ma for the retrograde metamorphism, which represents an exhumation age, suggesting a significant early Paleozoic tectonothermal event.

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The mineralogy, petrology, metamorphic PTDt trajectory and exhumation mechanism of blueschists, south Tianshan, northwestern China

Cited by 169 publications

References 23 publications

Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)

Paleozoic tectonics of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China)

Tracing the effects of high-pressure metasomatic fluids and seawater alteration in blueschist-facies overprinted eclogites: Implications for subduction channel processes

Geological, geochronological and geochemical features of granulites in the Eastern Tianshan, NW China

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