Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating.

	Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating.
	Wang, SS ; Hu, HG ; Li, PX ; Wang, YQ
刊名	ACTA PETROLOGICA SINICA
	2001-10-01
卷号	17 期号:4 页码:663-668
关键词	sibetun vertebrate basalt-andesite subvolcanic rock Ar-Ar dating Early Cretaceous
ISSN号	1000-0569
文献子类	Article
英文摘要	The geologic age of the feathered dinosaurs and early birds in Sihetun and its neighboring area in Beipiao, western Liaoning is appointed to different epoches of the Mesozoic Era, such as the Late Jurassic, the Early Cretaceous or the Late Jurassic - Early Cretaceous. Even the dating data are also very different. Recent report of the U-Pb age of 125.2 +/- 0.9 Ma of zircon separated from tuff in the bed 6 of the composite stratigraphic column of Yixian Formation in Sihetun and its neighboring area, indicated that the Sihetun vertebrate belonged to the Early Cretaceous. This paper provides new evidence from Ar-Ar dating. YL29 basalt-andesite was collected from the low part of the bed 2 of the composite stratigraphic column, and the sample yields a K-Ar age of 129.0 +/- 0.9 Ma. The Ar-Ar step-heating experiment performed on the YL29 basalt-andesite yields a remarkably simple pattern. Apparent ages from step 6 similar to 13, comprising over 90 percent of the release of Ar-39, are virtually concordant, and give a plateau age of 128.2 +/- 0.8 Ma. The Ar-Ar total gas age (all 15 steps) on the sample is 128.4 +/- 1.4 Ma. When all steps data are plotted on a correlation or isochron diagram, an age of 128.4 +/- 0.2 Ma is obtained. YL30 diabase was collected from the subvolcanic rock, which intruded into beds 5 similar to9. The Ar-Ar step-heating experiment on this sample yields a virtually concordant set of ages over 93 percent of the release of Ar-39 (step 7 similar to 12) with a plateau age of 122.3 +/- 0.5 Ma. The Ar-Ar total gas age (all 12 steps) on the diabase is 121.1 +/- 1.2 Ma. The age obtained from the isochron plot using all steps data points is 121.8 +/- 1.3 Ma, indistinguishable from the plateau age. About the Jurassic-Cretaceous boundary age, there are continuous disputations internationally and both 135 Ma and 144 Ma are proposed for the boundary. The Chinese geochronologists prefer the forme one. According to above Ar-Ar age data of YL29 basalt-andesite and YL30 diabase, the Sihetun vertebrate assemblage should be the Early Cretaceous in age.
WOS关键词	FEATHERED DINOSAURS ; EVOLUTION
WOS研究方向	Geology
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000172356500018
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/76647]
专题	中国科学院地质与地球物理研究所
通讯作者	Wang, SS
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 2.Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China 3.Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Beijing 100044, Peoples R China
推荐引用方式 GB/T 7714	Wang, SS,Hu, HG,Li, PX,et al. Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating.[J]. ACTA PETROLOGICA SINICA,2001,17(4):663-668.
APA	Wang, SS,Hu, HG,Li, PX,&Wang, YQ.(2001).Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating..ACTA PETROLOGICA SINICA,17(4),663-668.
MLA	Wang, SS,et al."Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating.".ACTA PETROLOGICA SINICA 17.4(2001):663-668.