Sm-Nd age dating and its significance of chert in soft sediment deformation structures from the Lower Cambrian Zhushadong Formation,Jinan of Shandong Province
Tian Hongshui, Lü Mingying, Zhang Banghua, Sang Zhongxi
School of Civil Engineering, Shandong Jianzhu University, Jinan 250101, Shandong
Abstract In southern Jinan area,some soft sediment deformation structures triggered by earthquake developed in siliceous dolostone layers of the Dingjiazhuang Member of the Lower Cambrian Zhushadong Formation,such as siliceous thixotropic veins,siliceous thixotropic subsidence and wedge, etc. A set of gray black cherts were sampled from the same soft-siliceous subsidence structure. Using the VG354 isotopic mass spectrometer(made in Britain)and the method of isotope mass spectrometry, the 147Sm/144Nd and 143Nd/144Nd isotope ratios of each samples were measured. By means of the Sm-Nd isochron,the cherts have been dating. The diagenetic ages of the 530.8±6.1 Ma were obtained for the set of gray black cherts,belonging to the early stage of the Early Cambrian.As the minimum time for a soft flint (colloidal silica) to form a lithified rock is 0.1 Ma, it can be inferred that the seismic sedimentary events occurred at 530.7±6.1 Ma.Since the dating result is close to the lower bound age of the Canglangpuan Stage,and there is exists no fossil in the Dingjiazhuang Member of the Zhushadong Formation of Shandong Province,and the whole Zhushadong Formation belongs to the Canglangpuan Stage in the key profile of the Zhushadong Formation of Henan Province. So it is implied that the Dingjiazhuang Member of the Zhushadong Formation belongs to the Canglangpuan Stage. Through dating,the first isotopic age of the Lower Cambrian of the western Shandong is got,which is possessed of some reference value and significance to define the time of seismic depositional events in the Early Cambrian,and also provides a new datum for the further study of the Cambrian strata in the area.
About author: Tian Hongshui, born in 1956, is a professor in Shandong Jianzhu University. Now he is mainly engaged in geology and seismic events. E-mail: tianhongshui@126.com.
Cite this article:
Tian Hongshui,Lü Mingying,Zhang Banghua et al. Sm-Nd age dating and its significance of chert in soft sediment deformation structures from the Lower Cambrian Zhushadong Formation,Jinan of Shandong Province[J]. JOPC, 2015, 17(1): 45-50.
Tian Hongshui,Lü Mingying,Zhang Banghua et al. Sm-Nd age dating and its significance of chert in soft sediment deformation structures from the Lower Cambrian Zhushadong Formation,Jinan of Shandong Province[J]. JOPC, 2015, 17(1): 45-50.
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