Palaeomagnetism of Neoproterozoic glacial rocks of the Huabei Shield: the North China Block in Gondwana

	Palaeomagnetism of Neoproterozoic glacial rocks of the Huabei Shield: the North China Block in Gondwana
	Piper, JDA ; Rui, ZQ
刊名	TECTONOPHYSICS
	1997-12-30
卷号	283 期号:1-4 页码:145-171
关键词	palaeomagnetism Neoproterozoic Cambrian glacial North China
ISSN号	0040-1951
文献子类	Article
英文摘要	A palaeomagnetic study is reported of reddened facies (Fengtai Formation) of Neoproterozoic glacial rocks which underlie Early Cambrian rocks with disconformity in the Huabei (North China/Sino-Korean) Block. The diamictite (preferred age 620-600 Ma) carries a dual polarity remanence residing in hematite of the red matrix. The mean direction derived from 62 samples is D/I = 205.9/-32.4 degrees (alpha(95) = 3.9 degrees) yielding a pole position at 233 degrees E, 62 degrees N. Tests on the matrix deformed beneath dropstones suggest that remanence was fixed before full compaction, although clasts near the base of the formation are largely overprinted. Overlying Early Cambrian sediments of the Houjiashan and Yutaishan formations have a similar remanence also of dual polarity (D/I = 205.5/-32.1 degrees, alpha(95) = 3.9 degrees, 32 samples). The magnetisation in the diamictite is therefore interpreted to have been acquired during loading by the ice sheet and/or the overlying Cambrian succession. Red shales from the Liulaobei Formation (similar to 890-840 Ma) near the base of the Neoproterozoic succession in the Huabei Block yield a contrasting remanence of D/I = 59.4/75.3 degrees (alpha(95) = 7.1 degrees, 19 samples) equivalent to a pole position at 150 degrees E, 43 degrees N. Pole positions from this study accord with Lower-Middle Cambrian poles from the Australian and South China Blocks with North China sited adjacent to northeastern Australia in accordance with recent biogeographic and palaeogeographic models. Although the palaeolatitude derived from the Fengtai diamictite (17 degrees) is Cambrian in age and probably later than the glaciation, the correlation with Australia implies that glaciation in North China took place in low palaeolatitudes (similar to 20 degrees) and reinforces the view that late Neoproterozoic glaciation, at least at this perimeter of Gondwana, occurred at low latitudes. Neoproterozoic-Cambrian poles from North China, South China and Australia fail to conform to the popular Rodinia reconstruction with the latter blocks adjacent to western North America and also fail to support the view that Gondwana formed by the fusion of widely separated eastern and western segments during Pan African orogeny. Instead they accord to poles from Africa and South America in a precursor of Gondwana (Protogondwana). The subsequent Palaeozoic derivation of this supercontinent was probably achieved by intracontinental strike-slip motion during Pan African deformation following extinction of the Afro-Arabian are.
WOS关键词	PALEOZOIC ROCKS ; SOUTH-AUSTRALIA ; SNOWBALL EARTH ; PALEOMAGNETISM ; SUPERCONTINENT ; MA ; LAURENTIA ; INTERVALS ; MINERALS ; BREAKUP
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000071661200006
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/74898]
专题	中国科学院地质与地球物理研究所
通讯作者	Piper, JDA
作者单位	1.Univ Liverpool, Dept Earth Sci, Geomagnetism Lab, Liverpool L69 7ZE, Merseyside, England 2.Acad Sinica, Inst Geol, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Piper, JDA,Rui, ZQ. Palaeomagnetism of Neoproterozoic glacial rocks of the Huabei Shield: the North China Block in Gondwana[J]. TECTONOPHYSICS,1997,283(1-4):145-171.
APA	Piper, JDA,&Rui, ZQ.(1997).Palaeomagnetism of Neoproterozoic glacial rocks of the Huabei Shield: the North China Block in Gondwana.TECTONOPHYSICS,283(1-4),145-171.
MLA	Piper, JDA,et al."Palaeomagnetism of Neoproterozoic glacial rocks of the Huabei Shield: the North China Block in Gondwana".TECTONOPHYSICS 283.1-4(1997):145-171.