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.
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.
陈晋鑣,武铁山,张鹏远,等. 1997. 华北区区域地层[M]. 湖北武汉:中国地质大学出版社,46-54. 陈文,万渝生,李华芹,等. 2011. 同位素地质年龄测定技术及应用[J]. 地质学报,85(11):1917-1946. 狄明信,马玉新,田海芹. 1996. 山东新泰盘车沟剖面寒武系硅质岩成因[J]. 石油大学学报,20(增刊):1-5. 国际地层委员会. 2013. 国际地层年度表[J]. 地层学杂志,37(3):257. 刘宝珺. 1980. 沉积岩石学[M]. 北京:地质出版社,232,443-444. 裴放,巴燕,王朝栋,等. 2009. 河南平顶山地区下寒武统朱砂洞组地质特征及成因[J]. 河南地球科学通报,(上册):34-44. 乔秀夫,高林志,彭阳,等. 2001. 古郯庐带沧浪铺阶地震事件层序及构造意义[J]. 中国科学(D辑),31(11):911-918. 乔秀夫,李海兵,邱祝礼. 2013. 震积岩:沉积岩中的古地震记录[A]. 见:冯增昭主编.中国沉积岩[M]. 北京:石油工业出版社,507-615. 山东省地质矿产局. 1991. 山东省区域地质志[M]. 北京:地质出版社,83. 山东省地质矿产局. 1996. 山东省岩石地层[M]. 湖北武汉:中国地质大学出版社,115-135. 田洪水,万中杰,王华林. 2003. 鲁中寒武系馒头组震积岩的发现及初步研究[J]. 地质论评,49(2):123-131. 田洪水,张邦花,祝介旺,等. 2011. 早寒武世初期沂沭断裂带地震效应[J]. 古地理学报,13(6):645-656. 王银喜,顾连兴,张遵忠,等. 2007. 东天山晚石炭世大石头群流纹岩Sr-Nd-Pb同位素地球化学研究[J]. 岩石学报,23(7):1749-1755. 杨杰东,郑文武,陶仙聪,等. 2004. 安徽淮南群四顶山组燧石Sm-Nd 年龄测定[J]. 地质论评,50(4):413-417. 张邦花,田洪水,张增奇,等. 2012. 地质名山馒头山及其附近早寒武世古地震沉积事件研究[J]. 沉积学报,30(6):1021-1031. Tian H S,Zhang Z Q,Zhang B H, et al. 2013. Tectonic taphrogenesis and paleoseismic records from the Yishu Fault Zone in the initial stage of the Caledonian movement[J]. Acta Geologica Sinica(English Edition),87(4):936-947. Wang Yinxi,Yang Jiedong,Chen Jun, et al. 2007. The Sr and Nd isotopic variations of the Chinese Loess Plateau during the past 7Ma:Implications for the East Asian winter monsoon and source areas of loess [J]. Palaeogeography, Palaeoclimatology, Palaeoecology,249(3-4):351-361.郑秀娟
