Major provenance of Jurassic sediments in Luxi uplift, eastern North China,derived from the northern North China Block: Evidences from detrital zircon U-Pb and Hf isotopic geochronology
Xu Jianqiang1,2, Li Zhong1, Shi Yonghong3
1. Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;
2. Graduate University of Chinese Academy of Sciences,Beijing 100049;
3. School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009
Relatively successive sequences of Late Mesozoic are preserved and exposed in Luxi uplift,eastern North China Block(NCB),which is an important region to study the Late Mesozoic tectonic evolution of the eastern NCB.In this study,detrital zircon U-Pb-Hf isotopic compositions of two Jurassic arkosic sandstones,respectively sampled from the Fangzi and Santai Formations,are measured through LA-MC-ICP-MS method,with aim to trace the Jurassic sediment provenances and tectonic-paleogeographic configuration.The two sample have very similar U-Pb age spectrums which can be divided into four major groups:Phanerozoic(Ⅰ),Late Mesoproterozoic to Early Neoproterozoic(Ⅱ),Paleoproterozoic(Ⅲ)and Neoarchean(Ⅳ).Detrital zircons of Group Ⅲ and Group Ⅳ broadly match the age spectra of the basement of NCB which exposed widely in the northern part.No Middle Neoproterozoic(850～700 Ma)magmatic zircon regarded as the provenance diagnostic for the South China Block(SCB)and Triassic metamorphic zircon are found in this study,ruling out the possibility of clastic provenance transportation from the Sulu orogen(belongs to SCB),adjacent to the Luxi area at present,to the Luxi area.The detrital zircons age of Phanerozoic age(393～256 Ma)from the two samples recording the Late Paleozoic magmatic activities which are not found both in Luxi and its peripheral areas,but can be well compared with that of the north NCB and the northern Xing-Meng orogen belt(XMOB).Furthermore,considerable proportion of Phanerozoic zircons(183 Ma, 462 Ma and 324～154 Ma)from the two samples with positive εHf(t)values(+0.9～+12.7)have similar Hf isotopes characteristic to the XMOB as well.In addition,the proportions of Phanerozoic zircons and the Phanerozoic zircons with positive εHf(t)value in the sandstone of Fangzi Formation are both higher than that of Santai Formation.This research proposes that an evident mountain or provenance region once increasingly developed along northern NCB during Early to Late Jurassic,easily providing mass clastic materials southward and becoming the major provenance of the Jurassic sediments in Luxi.
. Major provenance of Jurassic sediments in Luxi uplift, eastern North China,derived from the northern North China Block: Evidences from detrital zircon U-Pb and Hf isotopic geochronology[J]. Chinese Journal of Geology, 2012, 47(4): 1099-1115.