High-pressure metamorphic rocks from Tongbaishan, central China: U–Pb and 40Ar/39Ar age constraints on the provenance of protoliths and timing of metamorphism
Introduction
The Paleozoic–Mesozoic Qinling–Dabie–Sulu orogen marks the suture zone between the Sino-Korean and Yangtze cratons. The most important feature of the orogen is the preservation of high-pressure and ultrahigh-pressure (HP/UHP) metamorphic rocks of different ages. Regionally, Cambrian HP/UHP rocks occur in North Qinling (Qinling Group) (Hu et al., 1995, Hu et al., 1996, Yang et al., 2003a), whereas Triassic HP/UHP rocks are mainly distributed in the Dabieshan and Sulu areas (Hacker et al., 1996, Liou et al., 1996). Furthermore, some HP eclogites from the northwestern corner of western Dabieshan (i.e. Hong'an block) appear to have formed during the Silurian or Carboniferous time (Jian et al., 1997, Jian et al., 2000, Xu et al., 2000, Li et al., 2001, Sun et al., 2002). Since HP/UHP metamorphic rocks record the history of continental subduction, collision and subsequent exhumation, the multiple HP/UHP events registered in the Qinling–Dabie–Sulu orogen have well constrained the geodynamic evolution during the assembly of the Sino-Korean and Yangtze cratons.
The Tongbaishan area lies at the junction between the Paleozoic North Qinling orogen and the Mesozoic South Qinling–Dabie–Sulu orogen (Fig. 1). HP eclogites and their retrograde products have recently been recognized in several localities in this area (Wei et al., 1999, Suo et al., 2001, Liu et al., 2005). These rocks clearly holds key to the understanding of the evolution of the Qinling–Dabie–Sulu orogen, and therefore, geochronological data are most critical. Up to the present, however, the ages of these HP rocks remain unconstrained. In this paper, we report SHRIMP U–Pb ages on zircon and 40Ar/39Ar ages on muscovite from metabasites (eclogite and metagabbro) and their country rocks (gneiss, quartzite and schist) from the Tongbaishan area in order to (1) delineate the formation time and provenance of protoliths of the HP rocks, and (2) to date the event of HP metamorphism. The geodynamic evolution between the Sino-Korean and Yangtze cratons will be further discussed in conjunction with the available age data from the Dabie–Sulu HP/UHP metamorphic terrane.
Section snippets
Regional geology and HP metamorphism
The Tongbaishan area is separated from Qinling in the west by the Nanyang basin, and from western Dabieshan in the east by the Dawu fault (Fig. 1). The area comprises three Paleozoic and five Mesozoic metamorphic units. These metamorphic units are separated by large-scale shear zones as a result of extensional detachment at a late stage of exhumation (Zhong et al., 1999, Zhong et al., 2001, Suo et al., 2001). A major shear zone along the southwest boundary of the Tongbai complex (see below) has
Sample description
In order to precisely define ages of protolith and HP metamorphism, two fresh eclogites (samples HYH01-3 and SHZ08-1), a retrograde eclogite (sample GM02-1), a metagabbro (sample DFS03-1), a quartzofeldspathic orthogneiss (sample HYH01-11), a quartzofeldspathic paragneiss (sample SHZ03-5), a pelitic schist (sample TB02-1) and a quartzite (sample DFS06-1) from the northern and southern eclogite zones were chosen for SHRIMP U–Pb zircon dating. Furthermore, samples HYH01-11, SHZ03-5, DFS06-1 and
Sample HYH01-3: eclogite from the northern eclogite zone
Zircons from eclogite sample HYH01-3 are short prismatic and irregular in shape, with 50–150 μm in length. CL images reveal that most zircon grains are oscillatory-zoned, but the oscillatory bands have commonly been thickened and somewhat blurred (Fig. 2a,b). This feature reflects a magmatic origin of the zircons, which have undergone a post-magmatic solid-state recrystallization (Hoskin and Black, 2000). In addition, two zircon grains show grey homogeneous or cloudy-zoned pattern (Fig. 2c).
Age and provenance of protoliths
For the Qinling–Dabie–Sulu orogen, the ages of inherited zircons can be used to determine the provenance of the Sino-Korean or Yangtze craton and therefore the location of the suture (Hacker et al., 1998, Hacker et al., 2006). As generally accepted, the distinctive ca. 750 Ma bimodal magmatism are diagnostic of the Yangtze craton (Hacker et al., 1998, Hacker et al., 2000) and its occurrence was related to the rifting of the supercontinent Rodinia (Li et al., 2003). Four Neoproterozoic protolith
Conclusions
- (1)
U–Pb zircon analyses of eclogite, metagabbro and orthogneiss from the Tongbaishan area reveal an extensive bimodal magmatism in the period of 768–662 Ma, whereas detrital zircons from metasedimentary rocks reveal three major tectonothermal events of 2.49 Ga, 1.93 Ga and 1.85–1.82 Ga. The new age data suggest that the northern margin of the Yangtze craton involves a Paleoproterozoic orogenesis and a Neoproterozoic rifting.
- (2)
40Ar/39Ar dating of muscovite from quartzofeldspathic gneiss and quartzite
Acknowledgements
We would like to thank Ping Jian, Wei Zhang and Biao Song for assistance in the SHRIMP U–Pb zircon analyses and Wen Chen and Yan Zhang in the 40Ar/39Ar muscovite analyses. Critical reviews by two anonymous reviewers and editorial comments by I. Buick substantially improved the manuscript. The research of the senior author was supported by the National Natural Science Foundation of China (No. 40672047), Geological Investigation Project of China Geological Survey (1212010711812) and Free Research
References (76)
- et al.
Constraints on timing of peak and retrograde metamorphism in the Dabie Shan ultrahigh-pressure metamorphic belt, east-central China, using U–Th–Pb dating of zircon and monazite
Chem. Geol.
(2002) - et al.
TEMORA 1: a new standard for Phanerozoic U–Pb geochronology
Chem. Geol.
(2003) - et al.
Fine-scale isotopic heterogeneities and fluids in the deep crust: a 40Ar/39Ar laser ablation and TEM study of muscovites from a granulite–eclogite transition zone
Earth Planet. Sci. Lett.
(1997) - et al.
Coesite-bearing eclogites from the Bixiling Complex, Dabie Mountains, China: Sm–Nd ages, geochemical characteristics and tectonic implications
Chem. Geol.
(1996) - et al.
Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahigh-pressure collisional orogen, China: evidence from zircon ages
J. Asian Earth Sci.
(2003) - et al.
35 Ma old ultrahigh-pressure metamorphism and evidence for very rapid exhumation in the Dora Maira Massif, Western Alps
Lithos
(1997) - et al.
Zircon ages constrain the architecture of the ultrahigh-pressure Qinling–Dabie orogen, China
Earth Planet. Sci. Lett.
(1998) - et al.
The oldest UHP eclogites of the world: age of UHP metamorphism, nature of protoliths and tectonic implications
Chem. Geol.
(2001) - et al.
Geochemical and Geochronological constraints on the suture location between the North and South China Blocks in the Dabie orogen, central China
Phys. Chem. Earth (A)
(2001) - et al.
Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia
Precambrian Res.
(2003)
SHRIMP U–Pb zircon dating of a metagabbro and eclogites from western Dabieshan (Hong'an block), China, and its tectonic implications
Tectonophysics
Dating of prograde metamorphic events deciphered from episodic zircon growth in rocks of the Dabie–Sulu UHP complex, China
Earth Planet. Sci. Lett.
Tectonics of the Qinling (Central China): tectonostratigraphy, geochronology, and deformation history
Tectonophysics
Ages of ultrahigh pressure metamorphism and protolith orthogneisses from the eastern Dabie Shan: U/Pb zircon geochronology
Earth Planet. Sci. Lett.
Dating of eclogite-facies zircons: the age of Alpine metamorphism in the Sesia-Lanzo Zone (Western Alps)
Earth Planet. Sci. Lett.
UHP metamorphism and exhumation of the Dabie Orogen, China: evidence from SHRIMP dating of zircon and monazite from a UHP granitic gneiss cobble from the Hefei Basin
Geochim. Cosmochim. Acta
U–Pb, Hf and O isotopes evidence for two episodes of fluid-assisted zircon growth in marble-hosted eclogites from the Dabie Orogen
Geochim. Cosmochim. Acta
40Ar/39Ar thermochronology from the northwestern Dabie Shan: constraints on the evolution of Qinling–Dabie orogenic belt, east-central China
Tectonophysics
Zircon U–Pb age and Hf–O isotope evidence for Paleoproterozoic metamorphic event in South China
Precambrian Res.
Zircon U–Pb age and Hf isotope evidence for 3.8 Ga crustal remnant and episodic reworking of Archean crust in South China
Earth Planet. Sci. Lett.
Zircon U–Pb and oxygen isotope evidence for a large-scale 18O depletion event in igneous rocks during the Neoproterozoic
Geochim. Cosmochim. Acta
Zircon U–Pb age, Hf and O isotope constraints on protolith origin of ultrahigh-pressure eclogite and gneiss in the Dabie orogen
Chem. Geol.
Timing of collision of the Sino-Korean and Yangtze cratons: U–Pb zircon dating of coesite-bearing eclogites
Geology
Geochronology and isotopic character of ultrahigh-pressure metamorphism with implications for collision of the Sino-Korean and Yangtze Cratons, central China
Tectonics
Geochemical, age, and isotopic constraints on the location of the Sino-Korean/Yangtze suture and evolution of the Northern Dabie complex, east central China
Geol. Soc. Am. Bull.
The magmatism and deformation times of the Xidatan rock series, East Kunlun Mountain
Sci. China (Ser. B) (Supplement),
Preliminary study of microscale zircon oxygen isotopes for Dabie–Sulu metamorphic rocks: ion probe in situ analyses
Chin. Sci. Bull.
New achievements in the study of the excess argon in HP–UHP metamorphic minerals
Geochim. Cosmochim. Acta (Supplement)
Permo-Triassic collision, subduction-zone metamorphism, and tectonic exhumation along the East Asian continental margin
Annu. Rev. Earth Planet. Sci.
40Ar/39Ar geochronology and exhumation of high-pressure to ultrahigh-pressure metamorphic rocks in east central China
Geology
The Qinling–Dabie ultra-high-pressure collisional orogen
Exhumation of ultrahigh-pressure continental crust in east central China: Late Triassic–Early Jurassic tectonic unroofing
J. Geophys. Res.
High-temperature geochronology constraints on the tectonic history and architecture of the ultrahigh-pressure Dabie–Sulu Orogen
Tectonics
An empirical evaluation of the argon diffusion geometry in muscovite
Earth Planet. Sci. Lett.
Metamorphic zircon formation by solid-state recrystallization of protolith igneous zircon
J. Metam. Geol.
Petrography and metamorphism study on high-ultrahigh pressure eclogite from Guanpo area, northern Qinling Mountains
J. Mineral. Petrol.
Sm/Nd isochron age of eclogite from northern Qinling Mountains
Acta Mineral. Sin.
High-pressure/ultrahigh-pressure eclogites from the Hong'an Block, east-central China: geochemical characterization, isotope disequilibrium and geochronological controversy
Contrib. Mineral. Petrol.
Cited by (122)
Origin of the Early Cretaceous Be mineralization in the Tongbai-Dabie orogen, central China
2023, Ore Geology ReviewsArchean–Paleoproterozoic magmatism in the Xishui Complex, South China: Implications for crustal evolution and amalgamation of the Yangtze Block
2023, Journal of Asian Earth SciencesA new model for the segmentation, propagation and linkage of the Tan-Lu fault zone, East Asia
2023, Journal of Asian Earth Sciences