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	Is there a precursor to the Cretaceous normal superchron? New paleointensity and age determination from Liaoning province, northeastern China
	Zhu, RX ; Lo, CH ; Shi, RP ; Pan, YX ; Shi, GH ; Shao, J
	2004
关键词	paleointensity Ar-40/Ar-39 dating Cretaceous normal superchron andesitic basalt EARTHS MAGNETIC-FIELD GEOMAGNETIC-FIELD VOLCANIC-ROCKS INTENSITY HAWAII TIME INTERCALIBRATION PALEOMAGNETISM STANDARDS SEQUENCES
英文摘要	Although the geomagnetic reversal record for the past 160 Myr is relatively well documented, whether a precursor exists before the onset of the Cretaceous normal superchron (CNS) remains a contentious topic in the study of the evolution of geomagnetic reversals. In the present study we have tried to find out if new paleointensity data can provide more information about this topic. A paleointensity, geochronologic and paleomagnetic investigation has been conducted on four andesitic basalt lava flows from Hulahada in Liaoning Province, northeastern China. Radiometric Ar-40/Ar-39 dating experiments indicate the volcanism occurred at about 122.7 +/- 0.6 Myr, corresponding to marine anomaly Mln. Thermomagnetic experiments and hysteresis loops show that the main magnetic carrier of remanence are titanomagnetites with Curie temperatures of similar to580degreesC. Thirty-eight samples from three lavas underwent Thellier-Thellier paleointensity experiments with systematic partial thermoremanent magnetization (pTRM) checks. Ten samples from the studied lavas yield reliable paleointensity estimates with a mean virtual dipole moment (VDM*) of (4.8 +/- 0.2) x 10(22) Am-2, about half the strength of the modern-day field. Our paleointensity results in conjunction with previous data suggest that there is no precursor to the CNS. (C) 2004 Elsevier B.V. All rights reserved.; Geochemistry & Geophysics; SCI(E); CPCI-S(ISTP); 0
语种	英语
DOI标识	10.1016/j.pepi.2004.01.008
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/254611]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Zhu, RX,Lo, CH,Shi, RP,et al. Is there a precursor to the Cretaceous normal superchron? New paleointensity and age determination from Liaoning province, northeastern China. 2004-01-01.

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