A SHRIMP U-Pb zircon geochronology study of the tuff at the bottom of the Lower Cambrian Niutitang Formation at Songlin,Zunyi,South China yielded a mean 206Pb/238U age of 518±5 Ma.It is significantly younger than...A SHRIMP U-Pb zircon geochronology study of the tuff at the bottom of the Lower Cambrian Niutitang Formation at Songlin,Zunyi,South China yielded a mean 206Pb/238U age of 518±5 Ma.It is significantly younger than the Re-Os ages of 537―542 Ma for the overlying polymetallic Ni-Mo-PGE-rich layer in the basal Niutitang Formation at Songlin,suggesting that the Re-Os ages might represent that of the original magma chamber for the Ni-Mo-PGE-rich layer rather than the formation age of the strata.The intra-basinal stratigraphic correlation also implies that the absolute age of the Chengjiang biota should be younger than 518±5 Ma.Our new result,together with the SHRIMP U-Pb zircon age for the K-bentonite in the Zhongyicun member of the Zhujiaqing Formation at the Meishucun section,Yunnan Province,provides a temporal constraint for the Lower Cambrian of the Yangtze Platform in South China.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No.40672053)
文摘A SHRIMP U-Pb zircon geochronology study of the tuff at the bottom of the Lower Cambrian Niutitang Formation at Songlin,Zunyi,South China yielded a mean 206Pb/238U age of 518±5 Ma.It is significantly younger than the Re-Os ages of 537―542 Ma for the overlying polymetallic Ni-Mo-PGE-rich layer in the basal Niutitang Formation at Songlin,suggesting that the Re-Os ages might represent that of the original magma chamber for the Ni-Mo-PGE-rich layer rather than the formation age of the strata.The intra-basinal stratigraphic correlation also implies that the absolute age of the Chengjiang biota should be younger than 518±5 Ma.Our new result,together with the SHRIMP U-Pb zircon age for the K-bentonite in the Zhongyicun member of the Zhujiaqing Formation at the Meishucun section,Yunnan Province,provides a temporal constraint for the Lower Cambrian of the Yangtze Platform in South China.
文摘澄江生物群是认识寒武纪生命大爆发的重要窗口,它的分布范围一直仅限于滇东地区,最近在贵州遵义松林牛蹄塘组底部页岩中发现有Naronia,Archotuba conoidalis,Isoxys,Perspicaris,Lingulepis,Tsunyidiscus,Scenella,水母状化石(medusiform fossil),海绵动物化石Leptomitus,类似半索动物杆壁虫Rhabdopleura化石,软舌螺类Hyolithids,宏观藻类和疑源类化石Zunyiphyton perelegans Yang et Zhao,1999,Yuknessia sp.,Longenema Ding,1996,Sphaerocongregus variabilis等。其中有一部分是属于澄江生物群分子,这是云南省外澄江生物群分子的新发现。由于生物群之下40m处还产大量海绵动物、高肌虫和藻类化石等组成的松林生物群,其上又有下寒武统明心寺组古杯动物群,因此,这一生物群的发现对研究早寒武世生物的演化也具有一定的科学意义,同时,对澄江生物群的古生态学研究也具有重要意义。
