U–Pb and Hf isotopic study of zircons of the Helanshan Complex: Constrains on the evolution of the Khondalite Belt in the Western Block of the North China Craton

The Khondalite Belt is an east-west-trending Paleoproterozoic continental-continental collisional belt, separating the Western Block of the North China Craton into the Yinshan Block and the Ordos Block from north to south. In the past years, extensive metamorphic and geochronological investigations for pelitic granulites have been carried out in the Khondalite Belt. However, felsic granulites attract just a little attention although they are widely exposed in the field and potentially preserve key high-pressure information, thus hindering better understanding of the tectonic processes and settings of this critical area. In this study, a link between &#8216;inter-layered&#8217; felsic and pelitic granulites from the Qianlishan Complex of the Khondalite Belt was established based on comprehensive metamorphic analysis. Three distinct metamorphic stages including peak pressure (M1), post-peak decompression (M2) and late retrograde cooling (M3) stages have been identified in the felsic and pelitic granulites. Felsic granulites experienced high-pressure metamorphism up to ~12 kbar, while estimated peak pressure for pelitic granulites is 11-15 kbar. The decompression stage (M2) is represented by cordierite + sillimanite symplectite and/or cordierite coronae with conditions of 5.7-6.5 kbar/800-835 &#176;C in pelitic granulites, and by garnet-sillimanite assemblages formed at conditions of >6.5 kbar/810-865 &#176;C in felsic granulites. The later cooling stage (M3) is indicated by sub-solidus biotite-quartz-plagioclase symplectite and later melt crystallization. Clockwise P-T paths involving near-isothermal decompression and near-isobaric cooling were defined by these mineral assemblages and approximate P-T conditions, which suggest a continent-continent collisional event. SIMS zircon U-Pb dating yields a consistent metamorphic age of ~1.95 Ga from felsic granulites, interpreted as the timing of peak metamorphism. The results, combined with previously reported data, suggest that the Khondalite Belt formed by collision between the Yinshan and Ordos blocks at ~1.95 Ga.

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U–Pb and Hf isotopic study of detrital zircons from the Lüliang khondalite, North China Craton, and their tectonic implications

Geological Magazine ◽

10.1017/s0016756809006396 ◽

2009 ◽

Vol 146 (5) ◽

pp. 701-716 ◽

Cited By ~ 101

Author(s):

XIAOPING XIA ◽

MIN SUN ◽

GUOCHUN ZHAO ◽

FUYUAN WU ◽

LIEWEN XIE

Keyword(s):

North China Craton ◽

North China ◽

Detrital Zircons ◽

Crustal Material ◽

Isotopic Data ◽

Isotopic Study ◽

Metasedimentary Rocks ◽

The North ◽

Wide Range ◽

Western Block

AbstractTwo types of metasedimentary rocks occur in the Trans-North China Orogen of the North China Craton. One type consists of highly metamorphosed supracrustal rocks with protoliths of mature cratonic shale, called khondalites, as found in the Lüliang Complex; rocks of the other type are also highly metamorphosed but less mature, as represented by the Wanzi supracrustal assemblage in the Fuping Complex. U–Pb isotopic data for detrital zircons from khondalites show a provenance dominated by 1.9–2.1 Ga Palaeoproterozoic rocks. These detrital zircons display a wide range of εHfvalues from −16.0 to +9.2 and give Hf isotopic model ages mostly around 2.3 Ga. The high positive εHfvalues approach those for the depleted mantle at 2.1 Ga, highlighting a juvenile crustal growth event in Palaeoproterozoic times. Hf isotopic data also imply thatc.2.6 Ga old crustal material was involved in the Palaeoproterozoic magmatic event. These data are similar to those for the khondalitic rocks from the interior of the Western Block of the North China Craton, suggesting a common provenance. In contrast, other metasedimentary rocks in the Trans-North China Orogen, such as the Wanzi supracrustal assemblage in the Fuping Complex, have a source region with both Palaeoproterozoic and Archaean rocks. Their detrital zircon Hf isotopic data indicate reworking of old crustal material and a lack of significant juvenile Palaeoproterozoic magmatic input. These rocks are similar to the coevally deposited meta-sedimentary rocks in the interior of the Eastern Block. We propose that the Lüliang khondalites were deposited on the eastern margin of the Western Block in a passive continental margin environment and were thrust eastward later during collision with the Eastern Block. Other metasedimentary rocks in the Trans-North China Orogen were deposited on the western margin of the Eastern Block in a continental arc environment. Our data support the eastward subduction model for the Palaeoproterozoic tectonic evolution of the North China Craton.

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LA-ICP-MS U–Pb zircon ages of the Qianlishan Complex: Constrains on the evolution of the Khondalite Belt in the Western Block of the North China Craton

Precambrian Research ◽

10.1016/j.precamres.2009.06.008 ◽

2009 ◽

Vol 174 (1-2) ◽

pp. 78-94 ◽

Cited By ~ 256

Author(s):

Changqing Yin ◽

Guochun Zhao ◽

Min Sun ◽

Xiaoping Xia ◽

Chunjing Wei ◽

...

Keyword(s):

North China Craton ◽

North China ◽

The North ◽

Icp Ms ◽

Western Block ◽

Khondalite Belt

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Comparative studies on two phases of Archaean TTG magmas from different blocks of the North China Craton: petrogenesis and constraints on crustal evolution

Geological Magazine ◽

10.1017/s0016756820000618 ◽

2020 ◽

pp. 1-16

Author(s):

Houxiang Shan ◽

Mingguo Zhai ◽

RN Mitchell ◽

Fu Liu ◽

Jinghui Guo

Keyword(s):

North China Craton ◽

Lower Crust ◽

North China ◽

Tectonic Setting ◽

Source Material ◽

Crustal Growth ◽

Garnet Amphibolite ◽

The North ◽

Western Block ◽

Subducting Slab

Abstract Whole-rock major and trace elements and Hf isotopes of magmatic zircons of tonalite–trondhjemite–granodiorite (TTG) rocks with different ages (2.9, 2.7 and 2.5 Ga) from the three blocks (the Eastern Block, Western Block and Trans-North China Orogen) of the North China Craton were compiled to investigate their respective petrogenesis, tectonic setting and implications for crustal growth and evolution. Geochemical features of the 2.5 Ga TTGs of the Eastern Block require melting of predominant rutile-bearing eclogite and subordinate garnet-amphibolite at higher pressure, while the source material of the 2.7 Ga TTGs is garnet-amphibolite or granulite at lower pressure. The 2.5 Ga TTGs have high Mg#, Cr and Ni, negative Nb–Ta anomalies and a juvenile basaltic crustal source, indicating derivation from the melting of a subducting slab. In contrast, features of the 2.7 Ga TTGs suggest generation from melting of thickened lower crust. The 2.5 and 2.7 Ga TTGs in the Trans-North China Orogen were formed at garnet-amphibolite to eclogite facies, and the source material of the 2.5 Ga TTGs in the Western Block is most likely garnet-amphibolite or eclogite. The 2.5 Ga TTGs in the Trans-North China Orogen and Western Block were generated by the melting of a subducting slab, whereas the 2.7 Ga TTGs in the Trans-North China Orogen derived from melting of thickened lower crust. The Hf isotopic data suggest both the 2.5 and 2.7 Ga TTG magmas were involved with contemporary crustal growth and reworking. The two-stage model age (TDM2) histograms show major crustal growth between 2.9 and 2.7 Ga for the whole North China Craton.

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