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Liu J.,Chinese Academy of Geological Sciences | Liu F.,Chinese Academy of Geological Sciences | Ding Z.,Jilin University | Ding Z.,Exploration Institute of Geology and Mineral Resources | And 3 more authors.
Precambrian Research | Year: 2014

Paleoproterozoic granitoid rocks in the Jiaobei Terrane of the North China Craton mainly comprise deformed hornblende/biotite-bearing monzogranitic gneisses, undeformed biotite-bearing syenogranite, and tourmaline-bearing pegmatitic granite. In order to define the emplacement ages, sources, and petrogenesis of the granitoids, we have conducted a coupled LA-ICP-MS U-Pb dating, trace element and in situ Hf isotopic study of zircons from three representative Paleoproterozoic granitoid rocks in the Jiaobei Terrane. Our new zircon U-Pb data yield emplacement ages of 2181±12 and 1801±21Ma for deformed monzogranitic gneiss and undeformed syenogranite, respectively. The deformed hornblende/biotite-bearing monzogranitic gneisses in the Jiaobei Terrane, along with the Liaoji granitoids, define pre-tectonic granitoid events at ca. 2.2-2.0Ga, whereas the undeformed syenogranite corresponds to the post-tectonic or anorogenic granitoid event at ca. 1.8Ga. Zircons from the pre-tectonic hornblende-bearing monzogranitic gneiss have εHf(t) values varying from -2.13 to +6.18 (average=+1.2), two-stage Hf model ages (TDM2) of 2313-2780Ma and same trends of crustal evolution as ca. 2.5Ga TTG rocks, suggesting an origin by remelting of ca. 2.5Ga TTG rocks. Zircons from the pre-tectonic biotite-bearing monzogranitic gneiss have negative εHf(t) values of -7.36 to -2.85 (average=-5.26), two-stage Hf model ages (TDM2) of 2930-3206Ma and the same trends of crustal evolution as ca. 2.7 and/or ca. 2.9Ga TTG rocks, indicating derivation by partial melting of ca. 2.7 and/or ca. 2.9Ga TTG rocks. Zircons from the post-tectonic syenogranite display negative εHf(t) values ranging from-6.58 to -3.26 (average=-4.89), two-stage Hf model ages (TDM2) varying from 2663 to 2868Ma, and the same trends of crustal evolution as ca. 2.5Ga TTG rocks, indicating an origin by partial melting of ca. 2.5Ga TTG rocks. The linear belt of pre-tectonic, deformed A-type granitoid rocks with emplacement ages of 2.2-2.0Ga from the Liaoji area, Jiaobei Terrane, through to the Bengbu area of Anhui Province, together with the coeval mafic intrusions and bimodal volcanic assemblages, suggest that widespread extensions occurred along the Jiao-Liao-Ji Belt in the period of 2.2-2.0Ga. In contrast, the post-tectonic or anorogenic granitoid events may be linked to extensions following the amalgamation of the North China Craton. © 2013 Elsevier B.V. Source


Liu J.,Chinese Academy of Geological Sciences | Liu F.,Chinese Academy of Geological Sciences | Ding Z.,Jilin University | Ding Z.,Exploration Institute of Geology and Mineral Resources | And 2 more authors.
Acta Petrologica Sinica | Year: 2014

Identification and discovery of ancient continental crust is an important part of exploring the crustal evolutionary history of the early Earth, and zircon U-Pb age combined with zircon Hf isotope analysis is the major method of the research. In this study, we have conducted in situ U-Pb dating, rare earth element concentrations and Hf isotope analyses on detrital zircons from one felsic paragneiss sample collected from the Jiaobei Terrane, and many Early Archean detrital zircons have been identified. They are igneous origin on the base of analyses of their CL images, Th/U ratios and chondrite normalized REE patterns. The result of the U-Pb analyses indicates that two zircons yield ∼ 3. 40Ga (3413Ma and 3400Ma), and other seven zircons yield a weighted mean 207Pb/206Pb age of 3547 ± 19Ma (MSWD = 1. 16), suggesting that two magmatic events took place at ∼ 3. 40Ga and 3. 55Ga, respectively, combined with similar reports of other places in the North China Craton, implying that the Early Archean continental crust is much larger than present exposure of ancient continental crust. Most of these ancient detrital zircons have generally negative εHf(t) values from -6. 19 ∼0.95 (average = -2.54), two-stage Hf model ages of 3737 ∼ 4353 Ma (average = ∼4. 1Ga) which are much older than their U-Pb ages, implying the recycling of ancient continental crust (>3. 55Ga) and crustal growth prior to 4. 1Ga in the North China Craton. Source


Liu J.,Chinese Academy of Geological Sciences | Liu F.,Chinese Academy of Geological Sciences | Ding Z.,Exploration Institute of Geology and Mineral Resources | Liu P.,Chinese Academy of Geological Sciences | Wang F.,Chinese Academy of Geological Sciences
Acta Petrologica Sinica | Year: 2015

Early Precambrian major magmatic events are important geological processes of early growth and evolution of early continental crust. In this paper, we systematically summarized the studies on the petrography, zircon U-Pb geochronology, geochemistry and zircon Hf isotope for representative rocks of the Early Precambrian major magmatic events in the Jiaobei terrane. We defined three stages of Archean continental crustal growth by TTGs magmatisms at ∼ 2.9Ga, 2.7Ga and 2.5Ga, respectively. The TTGs are of geochemical characteristics of typical high-Al TTGs. They have positive zircon εHf(t) values, and two-stage Hf model ages clustering at ca. 3.3 ∼ 2.7Ga. Two alternative tectonic models are proposed to account for petrogenesis of the TTGs: (1) partial melting of thickened mafic lower crust; or (2) partial melting of oceanic crust during slab subduction. Nevertheless, the first one might be more appropriate for the Archean TTGs on the base of temporally episodic emplacements, spatially planar distribution, and low Mg number, Cr and Ni concentrations of the TTGs. We confirmed that there are multi-stage Paleoproterozoic granitic magmatisms by remelting of continental crust. By synthesizing the previous researches, we summarize that the growth and evolutional history of Early Precambrian continental crust in the Jiaobei terrane is following: 1) > ∼ 2.9Ga, the Jiabei terrane were dominated by basic crust (oceanic crust) with limited Early Archean continental crust which had been denuded; 2) At ∼ 2.9Ga, 2.7Ga and 2.5Ga, the ca. 3.3 ∼ 2.7Ga juvenile thickened basaltic lower crust experienced episodic partial melting companied with remelting of continental crust triggered by upwelling of mantle plume, and formed the Archean continental crust consisting of plenty of TTGs and minor continental crust-remelted (high K) granites; 3) During ca. 2.2 ∼ 2.0Ga, the continental crust took place rifting and thinning caused by upwelling of mantle materials, resulting in formation of ca. 2.2 ∼ 2.0Ga granitoids by remelting of the continental crust; 4) During ca. 1.95 ∼ 1.85 Ga, the Jiaobei terrane underwent granulite to high amphibolite facies metamorphism caused by collision-related tectonic processes and closing of the rift; 5) At ∼ 1.8 Ga, the continental crust underwent extension and thinning again caused by upwelling of mantle materials, which resulted in formation of ∼ 1.8 Ga granites by remelting of the continental crust. Source


Liu J.,Chinese Academy of Geological Sciences | Liu F.,Chinese Academy of Geological Sciences | Ding Z.,Jilin University | Ding Z.,Exploration Institute of Geology and Mineral Resources | And 3 more authors.
Acta Petrologica Sinica | Year: 2012

The Jiaobei terrane located in the eastern margin of the North China Craton (NCC), is commonly regarded as the southwestern segment of the Jiao-Liao-Jiao belt, and underwent polyphase magmatic and metamorphic events during Early Precambrian. In order to confirm the nature of the ∼2. 5Ga magmatic event which is the most significant magmatic event in the Jiaobei terrane, as well as in the NCC, in this study, two representative tonalitic and granitic gneiss samples with zircon U-Pb ages of ∼ 2. 5Ga are performed in zircon Hf isotopic analysis. The results of total 69 zircon Hf isotopic analyses show that they have positive εHf(t) values ranging from 10. 71 to 3. 0 with an average of 6. 02: Their two-stage Hf model ages (tDM2) mainly range from 2. 6Ga to 2. 9Ga (an average of 2747Ma), and older than their zircon 207Pb/206 Pb ages of ∼2. 5Ga, suggest that the ∼2. 5Ga TTG and granitic rocks were mainly derived from remelting or reworking of juvenile crusts forming during 2. 6 ∼2. 9Ga. In addition, a few zircons from the gneisses have strongly positive εHf(t) values of 7. 03 to 10. 71, and their zircon Hf model ages are close to zircon U-Pb ages representing the timing of zircon growth, indicative of new addition of coeval depleted mantle material to crust. Based on the results of zircon Hf isotopic analyses presented in this study and available Nd isotopic data published in previous studies, we suggest that the ∼2. 5Ga magmatic event in the Jiaobei terrane represents the remelting or reworking of juvenile crust, which is linked to the underplating of large amounts of mantle-derived magmas, and ∼ 2. 9Ga and 2. 7 ∼ 2. 8Ga are two periods of crustal growth, especially, 2. 7 ∼ 2. 8Ga is the most significant period of crustal growth in the Jiaobei terrane, as well as other areas in the NCC. Source


Liu J.,Chinese Academy of Geological Sciences | Liu F.,Chinese Academy of Geological Sciences | Liu P.,Chinese Academy of Geological Sciences | Wang F.,Chinese Academy of Geological Sciences | Ding Z.,Exploration Institute of Geology and Mineral Resources
Acta Petrologica Sinica | Year: 2011

Tonalite-trondhjemite-granodiorite (TTG) gneisses and granitic gneisses are widely distributed in the Early Precambrian metamorphic basement of Jiaobei terrane. In this study, we link cathodoluminescence (CL) images, U-Pb ages, and trace element compositions obtained from distinct zircon domains of complex zircons to unravel the origin, polyphase protolith and metamorphic ages of TTG gneisses and granitic gneisses in Jiaobei terrane. Zircons separated from 6 studied samples record four groups of magmatic ages of 2909 ±13Ma, 2738 ±23Ma, 2544 ±15 ∼2564 ±12Ma and 2095 ±12Ma, and two groups of metamorphic ages of 2504 ±16 ∼2513 ±32Ma and 1863 ±41Ma. A combined study of previously geochemical and Nd isotope data provides insight into the nature of TTG gneisses and granitic gneisses in the Jiaobei terrane. The TTG magmatic event took place at ∼2738 Ma may represent the major crust-growth episode. In contrast, the magmatic event took place at 2544 ∼ 2564Ma may represent the remelting of the older crustal materials, which was the most significantly magmatic event in the North China Craton (NCC). Whereas the magmatic event took place at ∼2095 Ma may reflect a period of magmatism related to an extension setting along the Jiao-Liao-Ji tectonic belt. A Neoarchean metamorphic event (2504 ∼ 2513Ma) may be linked to the underplating of large amounts of mantle-derived magmas which are considered to be related to upwelling mantle plumes (hot-spots). A Paleoproterozoic metamorphic event (∼1863Ma) recorded in the TTG gneisses, however, is consistent with the timing of high-pressure (HP) granulite facies metamorphism of mafic and pelitic HP granulites in Jiaobei terrane, implying the TTG gneisses also experienced the Paleoproterozoic HP granulite facies metamorphism. These evidences indicate that a significant continent-continent collision event did take place within the Jiaobei terrane at Paleoproterozoic. Source

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