Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain th...Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain their genesis and tectonic significance.Zircon LA-ICP-MS U-Pb data indicate that the rhyolite and rhyolitic lithic crystal tuff were formed during 137±5 Ma and 143±1 Ma,respectively.These volcanic rocks have high SiO2(70.03%–76.46%)and K2O+Na2O(8.10%–9.52%)contents,but low CaO(0.03%–0.95%)and MgO(0.07%–0.67%)contents,which belong to the peraluminous and high-K calc-alkaline rocks.They are enriched in light rare earth elements(REEs),and exhibit fractionation of light over heavy REEs,withδEu values of 0.37–0.83.The volcanic rocks are enriched in LILEs(e.g.,Rb,U and K)and depleted in HFSEs(e.g.,Nb,Ti,P and Ta).The chemical composition suggests that these volcanic rocks formed by partial melting of crust material.Combined with previous regional research results,the authors consider that the volcanic rocks of the Manketouebo Formation in the Keyihe area were formed under an extensional environment related to the closure of the Mongolia–Okhotsk Ocean.展开更多
The paleoposition of North China Craton in Rodinia has long been in controversial. This paper mainly focuses on the U-Pb geochronological studies of detrital zircons obtained from Bayan Obo Group exposed in the Shangd...The paleoposition of North China Craton in Rodinia has long been in controversial. This paper mainly focuses on the U-Pb geochronological studies of detrital zircons obtained from Bayan Obo Group exposed in the Shangdu area, Inner Mongolia, aiming to provide more information for interprating this problem. Based on the acquired data, this paper comes to the following conclusions. Firstly, the depositional age of Bayan Obo Group might be from Meso- to Neoproterozoic according to the zircons U-Pb dating results. The lower succession of this group, namely Dulahala and Jianshan formations deposited between 1800 and 1650 Ma. The Halahuogete and Bilute formations deposited between 1500 and 1350 Ma. For Baiyinbaolage and Hujiertu formations, their depositional age was 1250-900 Ma. Secondly, for the provenance of Bayan Obo Group, this paper believes detrital zircons with age of 2.51-2.71 Ga and 2.00-2.48 Ga were from Guyang, Xi Ulanbulang and Zhuozi area;the Khondalite Belt provided detrital zircons with age of 1.95-1.80 Ga;zircons with age of 1.60-1.75 Ga might come from granitic rocks in Miyun Area. The magmatism after 1.60 Ga was rarely recorded in the NCC, therefore those zircons with ages younger than 1.60 Ga might come from outside of NCC. The magmatism with the same age existed in Baltic, Amazonia and Laurentia. Based on previous paleomagnetic researches, this paper proposes that NCC might receive detritus from Baltic during 1560-1350 Ma and had affinity with Laurentia and Amazonia at ~0.9 Ga in Rodinia. Baltic, Amazonia and Laurentia might be potential provenances for non-NCC detritus in Bayan Obo Group.展开更多
Objective The North China Craton(NCC)is almost continuously widespread TTGs of 3.8–2.5 Ga,and the intrusive peak appears at^2.53 Ga,indicating that the Neoarchean is the most important period of continental growth in...Objective The North China Craton(NCC)is almost continuously widespread TTGs of 3.8–2.5 Ga,and the intrusive peak appears at^2.53 Ga,indicating that the Neoarchean is the most important period of continental growth in the NCC(Wan Yusheng et al.,2017).Recently studies reveal that the TTGs were formed during^2.7 Ga and 2.6–2.5 Ga in southern Jilin Province,NE of the NCC(Wang Chaoyang et al.,2017;Guo et al.,2017),whereas 2.7–2.6展开更多
始太古代及形成时代更古老的岩石十分稀少,任何新的发现都是对最早期陆壳形成演化研究的重要贡献。本文首次报道了华北克拉通冀东地区~3.8 Ga TTG岩石的年龄和地球化学组成。样品J2012为花岗闪长质片麻岩,J2013为侵入花岗闪长质片麻岩...始太古代及形成时代更古老的岩石十分稀少,任何新的发现都是对最早期陆壳形成演化研究的重要贡献。本文首次报道了华北克拉通冀东地区~3.8 Ga TTG岩石的年龄和地球化学组成。样品J2012为花岗闪长质片麻岩,J2013为侵入花岗闪长质片麻岩的花岗闪长岩脉,也遭受变质变形。两者的岩浆锆石年龄分别为3785±8 Ma和3773±6 Ma。尽管岩石的常量元素组成和形成时代类似,但稀土模式明显不同。样品J2012的TREE(稀土总量)和(La/Yb)n比值分别为139.2×10^(-6)和8.44,组成特征与北美4.03 Ga Acasta片麻岩类似,岩浆作用发生在相对低压的条件下,岩浆作用过程中无石榴子石参与而有斜长石存在。样品J2013的TREE和(La/Yb)n比值分别为163.5×10^(-6)和51.16。轻重稀土强烈分异要求花岗闪长岩形成于石榴子石稳定和斜长石不稳定的高压条件下。研究表明,冀东地区在~3.8 Ga时TTG岩浆作用就显示出多样性,支持了古太古代早期—冥古宙陆壳基底广泛存在的认识。根据始太古代岩石类型和组成特征等综合对比,认为鞍本和冀东是华北克拉通2个不同的古陆核形成演化中心。展开更多
Diabase sills with baddeleyite/zircon U-Pb ages of-1.32 Ga have been found in many areas of the North China Craton(NCC)(Peng,2015).Some researchers have proposed that this magmatic event should be related to the break...Diabase sills with baddeleyite/zircon U-Pb ages of-1.32 Ga have been found in many areas of the North China Craton(NCC)(Peng,2015).Some researchers have proposed that this magmatic event should be related to the breakup of the Columbia supercontinent.A few studies have reported this period of granitoids only to be present in the Shangdu,Huade.and Sonid Zuoqi areas(Zhang et al.,2012;Sun I.ixin et al..2018).This study concerns the first discovery of a-1.37 Ga granite in the southern Jilin Province,in the eastern part of the northern margin of the NCC.It has great significance for the study of the breakup of the Colombia supercontinent,the magmatism of the NCC,and the relationship between the supercontinent and other continents during this period.展开更多
基金Supported by Project of National Natural Science Foundation of China(No.41872234)。
文摘Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain their genesis and tectonic significance.Zircon LA-ICP-MS U-Pb data indicate that the rhyolite and rhyolitic lithic crystal tuff were formed during 137±5 Ma and 143±1 Ma,respectively.These volcanic rocks have high SiO2(70.03%–76.46%)and K2O+Na2O(8.10%–9.52%)contents,but low CaO(0.03%–0.95%)and MgO(0.07%–0.67%)contents,which belong to the peraluminous and high-K calc-alkaline rocks.They are enriched in light rare earth elements(REEs),and exhibit fractionation of light over heavy REEs,withδEu values of 0.37–0.83.The volcanic rocks are enriched in LILEs(e.g.,Rb,U and K)and depleted in HFSEs(e.g.,Nb,Ti,P and Ta).The chemical composition suggests that these volcanic rocks formed by partial melting of crust material.Combined with previous regional research results,the authors consider that the volcanic rocks of the Manketouebo Formation in the Keyihe area were formed under an extensional environment related to the closure of the Mongolia–Okhotsk Ocean.
基金financially supported by the National Natural Science Foundation of China (No.41872203)China Geological Survey (No.1212011120709)Doctoral Candidate Inter Discipline Fund of Jilin University (No.10183201837)
文摘The paleoposition of North China Craton in Rodinia has long been in controversial. This paper mainly focuses on the U-Pb geochronological studies of detrital zircons obtained from Bayan Obo Group exposed in the Shangdu area, Inner Mongolia, aiming to provide more information for interprating this problem. Based on the acquired data, this paper comes to the following conclusions. Firstly, the depositional age of Bayan Obo Group might be from Meso- to Neoproterozoic according to the zircons U-Pb dating results. The lower succession of this group, namely Dulahala and Jianshan formations deposited between 1800 and 1650 Ma. The Halahuogete and Bilute formations deposited between 1500 and 1350 Ma. For Baiyinbaolage and Hujiertu formations, their depositional age was 1250-900 Ma. Secondly, for the provenance of Bayan Obo Group, this paper believes detrital zircons with age of 2.51-2.71 Ga and 2.00-2.48 Ga were from Guyang, Xi Ulanbulang and Zhuozi area;the Khondalite Belt provided detrital zircons with age of 1.95-1.80 Ga;zircons with age of 1.60-1.75 Ga might come from granitic rocks in Miyun Area. The magmatism after 1.60 Ga was rarely recorded in the NCC, therefore those zircons with ages younger than 1.60 Ga might come from outside of NCC. The magmatism with the same age existed in Baltic, Amazonia and Laurentia. Based on previous paleomagnetic researches, this paper proposes that NCC might receive detritus from Baltic during 1560-1350 Ma and had affinity with Laurentia and Amazonia at ~0.9 Ga in Rodinia. Baltic, Amazonia and Laurentia might be potential provenances for non-NCC detritus in Bayan Obo Group.
基金supported by the National Science Foundation of China(grant No.41272223)China Geological Survey(grants No.12120114028001,121201004000150017-28 and 121201004000160901-7)Graduate Innovation Fund of Jilin University
文摘Objective The North China Craton(NCC)is almost continuously widespread TTGs of 3.8–2.5 Ga,and the intrusive peak appears at^2.53 Ga,indicating that the Neoarchean is the most important period of continental growth in the NCC(Wan Yusheng et al.,2017).Recently studies reveal that the TTGs were formed during^2.7 Ga and 2.6–2.5 Ga in southern Jilin Province,NE of the NCC(Wang Chaoyang et al.,2017;Guo et al.,2017),whereas 2.7–2.6
文摘始太古代及形成时代更古老的岩石十分稀少,任何新的发现都是对最早期陆壳形成演化研究的重要贡献。本文首次报道了华北克拉通冀东地区~3.8 Ga TTG岩石的年龄和地球化学组成。样品J2012为花岗闪长质片麻岩,J2013为侵入花岗闪长质片麻岩的花岗闪长岩脉,也遭受变质变形。两者的岩浆锆石年龄分别为3785±8 Ma和3773±6 Ma。尽管岩石的常量元素组成和形成时代类似,但稀土模式明显不同。样品J2012的TREE(稀土总量)和(La/Yb)n比值分别为139.2×10^(-6)和8.44,组成特征与北美4.03 Ga Acasta片麻岩类似,岩浆作用发生在相对低压的条件下,岩浆作用过程中无石榴子石参与而有斜长石存在。样品J2013的TREE和(La/Yb)n比值分别为163.5×10^(-6)和51.16。轻重稀土强烈分异要求花岗闪长岩形成于石榴子石稳定和斜长石不稳定的高压条件下。研究表明,冀东地区在~3.8 Ga时TTG岩浆作用就显示出多样性,支持了古太古代早期—冥古宙陆壳基底广泛存在的认识。根据始太古代岩石类型和组成特征等综合对比,认为鞍本和冀东是华北克拉通2个不同的古陆核形成演化中心。
基金the National Science Foundation of China(grant No.41872203 and 41872234)the Doctoral Candidate Interdiscipline Fund of Jilin University(grant No.10183201837).
文摘Diabase sills with baddeleyite/zircon U-Pb ages of-1.32 Ga have been found in many areas of the North China Craton(NCC)(Peng,2015).Some researchers have proposed that this magmatic event should be related to the breakup of the Columbia supercontinent.A few studies have reported this period of granitoids only to be present in the Shangdu,Huade.and Sonid Zuoqi areas(Zhang et al.,2012;Sun I.ixin et al..2018).This study concerns the first discovery of a-1.37 Ga granite in the southern Jilin Province,in the eastern part of the northern margin of the NCC.It has great significance for the study of the breakup of the Colombia supercontinent,the magmatism of the NCC,and the relationship between the supercontinent and other continents during this period.
