DOI: 10.1016/j.tecto.2020.228453
论文题名: Palaeomagnetism of the Dundas–Fossey Trough, Tasmania: Oroclinal rotation and Late Cretaceous overprinting
作者: Musgrave R.J. ; Job K.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 786 语种: 英语
中文关键词: Cretaceous superchron
; East Gondwana
; Orocline
; Overprint
; Paleomagnetism
; Tasmania
英文关键词: Hematite
; Lithology
; Magnetite
; Rotation
; Temperature
; Asthenospheric flow
; Declination datum
; Late cretaceous
; Low temperatures
; Magnetic analysis
; Meteoric waters
; Palaeomagnetism
; Subduction zones
; Geomagnetism
; asthenosphere
; Cretaceous
; demagnetization
; Gondwana
; hematite
; magnetite
; overprinting
; paleomagnetism
; subduction zone
; trough
; Australia
; Tasmania
英文摘要: The Dundas–Fossey Trough, a curved belt of Early Palaeozoic rocks in western and northern Tasmania, is hypothesised to have developed as an orocline driven by asthenospheric flow behind a rapidly retreating subduction zone on the East Gondwana margin. Rocks of the Wurawina Supergroup from the trough were sampled for a palaeomagnetic test of this hypothesis. Rock magnetic analysis identifies both magnetite and hematite remanence carriers. Hematite carries a normal-polarity overprint which was acquired at relatively low temperature. Thermal demagnetisation over the magnetite unblocking range reveals a linear trend that defines component A, which displays both normal and reversed polarity. Component A passes a modified version of the fold test, indicating that it is pre-deformational. The declination of component A correlates linearly with regional strike, thus passing the orocline test. A palaeomagnetic pole for the Cambrian Owen Group, after correction for oroclinal rotation, is displaced from the Gondwana polar wander path, suggesting that the western limb of the trough may have been rotated anticlockwise by about 40° prior to the development of the orocline, presumably during known Early to Middle Ordovician deformation. Adjustment of the palaeomagnetic declination data to account for this earlier phase of rotation improves the fit parameters of the orocline test. The palaeomagnetic results are consistent with the orocline model for the Dundas–Fossey Trough, and support the inference that the trough extends beneath later cover in southeastern Tasmania. Overprint component B yields a mean pole in broad agreement with other overprints previously observed both in Tasmania and the eastern seaboard of the Australian mainland, and like them appears to have been acquired during the Late Cretaceous normal polarity superchron. We speculate that magnetic overprinting in Tasmania is related to enhanced oxidation by meteoric water driven by regional uplift. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170666
Appears in Collections: 气候变化与战略
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作者单位: Geological Survey of New South Wales, Department of Regional NSW, 516 High Street, Maitland, NSW 2320, Australia; PALM Laboratory, Centre for Frontier Geoscience, Newcastle Institute for Energy and Resources, University of NewcastleNSW 2308, Australia; School of Earth Sciences, University of Tasmania, TAS, Hobart, 7001, Australia
Recommended Citation:
Musgrave R.J.,Job K.. Palaeomagnetism of the Dundas–Fossey Trough, Tasmania: Oroclinal rotation and Late Cretaceous overprinting[J]. Tectonophysics,2020-01-01,786