DOI: 10.1016/j.gloplacha.2012.11.008
论文题名: Anisotropy of thermoremanent magnetisation of Cryogenian glaciogenic and Ediacaran red beds, South Australia: Neoproterozoic apparent or true polar wander?
作者: Schmidt P.W. ; Williams G.E.
刊名: Global and Planetary Change
ISSN: 0921-8220
出版年: 2013
卷: 110 起始页码: 289
结束页码: 301
语种: 英语
英文关键词: Glaciation
; Inclination shallowing
; Neoproterozoic
; Palaeomagnetism
; Red beds
; South Australia
Scopus关键词: Glaciation
; Inclination shallowing
; Neoproterozoic
; Palaeomagnetism
; Red bed
; South Australia
; Anisotropy
; Clay minerals
; Deposition
; Geomagnetism
; Magnetization
; Remanence
; Glacial geology
; anisotropic medium
; anisotropy
; atmospheric correction
; compaction
; data set
; depositional environment
; glaciation
; isotherm
; magnetic property
; magnetization
; paleolatitude
; paleomagnetism
; Proterozoic
; red bed
; temperature effect
; Australia
; South Australia
英文摘要: Determining the effects of compaction-related inclination shallowing of remanence directions is crucial for ascertaining the validity of low palaeolatitudes for Neoproterozoic red beds in South Australia that are central to the debate concerning low-latitude Proterozoic glaciation. The inclination correction (or flattening) factor, f, is defined as tan(ID)/tan(IF), where ID and IF are the inclinations of the measured detrital remanence and the ancient inducing field, respectively. The anisotropy can be estimated using anisotropy of magnetic susceptibility and the anisotropy of high-field isothermal remanence (hf-AIR). The elongation-inclination (E-I) method has also been used to infer inclination shallowing. We add the anisotropy of thermoremanent magnetisation (ATR) to these methods. For the late Cryogenian Elatina Formation arenites, which constitute the bulk of the Elatina data set, the inclination correction using f=0.738 derived from ATR increases the palaeolatitude of the Elatina Formation from 6.5±2.2° to 8.8±3.2°, which confirms that the Elatina glaciation occurred near the palaeoequator. Inclination corrections for the Ediacaran argillaceous Brachina and Wonoka formations, using f=0.35-0.38 derived from ATR, are significantly greater than for the more arenaceous Elatina Formation, which increases their palaeolatitudes from ~12° to ~30°. Carbonates from the basal Ediacaran Nuccaleena Formation yielded f=0.8 from ATR, which represents only a small palaeolatitude correction from 19° to 23°. The anisotropy results imply that the characteristic remanent magnetisations carried by all these units were acquired early as depositional remanent magnetisations, essentially at the time of deposition. The shift of the palaeopoles from argillaceous units indicating significantly higher palaeolatitudes introduces a distinctive loop into the late Cryogenian-Ediacaran-Cambrian pole path for Australia. This loop shows similarities with the North American pole path for this period, for which true polar wander (TPW) has been inferred. However, until ages of Neoproterozoic strata in South Australia are better constrained uncertainty persists on whether the similarities of the Australian and North American pole paths reflect TPW. © 2012. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84888768099&doi=10.1016%2fj.gloplacha.2012.11.008&partnerID=40&md5=f6e7e8374828dfa139144385cec024fe
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/11126
Appears in Collections: 全球变化的国际研究计划
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作者单位: CSIRO Earth Science and oResource Engineering, PO Box 136, North Ryde, NSW 1670, Australia
Recommended Citation:
Schmidt P.W.,Williams G.E.. Anisotropy of thermoremanent magnetisation of Cryogenian glaciogenic and Ediacaran red beds, South Australia: Neoproterozoic apparent or true polar wander?[J]. Global and Planetary Change,2013-01-01,110.