气候变化领域集成服务门户(CCPortal): Deciphering deformation in ultramafic intrusions via magnetic fabric (AMS) and palaeomagnetic studies, Savannah Ni-PGE camp, NW Australia

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DOI	10.1016/j.tecto.2020.228608
	Deciphering deformation in ultramafic intrusions via magnetic fabric (AMS) and palaeomagnetic studies, Savannah Ni-PGE camp, NW Australia
	Austin J.R.; Patterson B.O.
发表日期	2020
ISSN	00401951
卷号	793
英文摘要	Knowledge of the internal architecture of mafic-ultramafic intrusions is critical to efficient targeting of magmatic Ni-PGE mineralisation. However, the visual homogeneity of such rocks in drill-core, coupled with poor outcrop in many areas can make their structure difficult to decipher using standard techniques. In this study we use measurements of anisotropy of magnetic susceptibility (AMS) and remanent magnetisation to examine the structural history of four adjacent, temporally equivalent, ultramafic intrusions from the east Kimberley Province, NW Australia. Whilst temporally equivalent, the intrusions have contrasting shape including bladed dyke, sill and stock geometries, and are hosted in rocks of contrasting rheology, including mafic granulite and meta-sedimentary migmatite. Early palaeomagnetic signatures present at Savannah and Savannah North originally had shallow NNE- to ENE-oriented inclinations, consistent with acquisition at low palaeolatitudes at ca 1800 Ma. However, these primary magnetisations were subsequently rotated during the ca. 1810 Ma Mount Stafford Event and/or ca. 1400–1200 Ma Yampi Orogeny, demonstrating that significant deformation occurred post-emplacement. Magmatic fabrics observed in AMS data for Savannah, Savannah North and Dave Hill all show evidence of NE or SW rotation during the same events. However, whilst there are similarities in the implied shortening directions across all four intrusions, they each preserve a unique deformation style, which is attributed to the unique shape of each intrusion coupled with the contrasting rheology of their respective host rocks. Each intrusion preserves a common dominant palaeomagnetic signature which is consistent with a high-grade metamorphic overprint at ca. 1200 Ma during the latter stages of the Yampi Orogeny. The lack of subsequent rotation of this dominant palaeomagnetic signature demonstrates that the majority of deformation pre-dates the Yampi event. This study demonstrates that even where tectonic conditions are similar, that intrusion shape and host rock rheology exert strong control on their deformation style. © 2020
关键词	Anisotropy of magnetic susceptibility (AMS)Kimberley Province Mafic – ultramafic intrusion Nickel-PGE mineralisation Palaeomagnetism Tectonothermal history
英文关键词	Core drilling; Deformation; Elasticity; Geomagnetism; Magnetic anisotropy; Magnetic susceptibility; Magnetization; Sedimentary rocks; Structural geology; Anisotropy of magnetic susceptibility; High grades; Internal architecture; Mafic granulites; Magmatic fabrics; Magnetic fabrics; Measurements of; Mineralisation; Nickel compounds; deformation; igneous intrusion; magnetic anisotropy; magnetic susceptibility; mineralization; paleomagnetism; petrogenesis; petrology; ultramafic rock; Australia; Kimberley [Western Australia]; Western Australia; Dioscorea trifida
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207708
作者单位	CSIRO Mineral Resources, 36 Bradfield Rd, Lindfield, NSW 2070, Australia
推荐引用方式 GB/T 7714	Austin J.R.,Patterson B.O.. Deciphering deformation in ultramafic intrusions via magnetic fabric (AMS) and palaeomagnetic studies, Savannah Ni-PGE camp, NW Australia[J],2020,793.
APA	Austin J.R.,&Patterson B.O..(2020).Deciphering deformation in ultramafic intrusions via magnetic fabric (AMS) and palaeomagnetic studies, Savannah Ni-PGE camp, NW Australia.Tectonophysics,793.
MLA	Austin J.R.,et al."Deciphering deformation in ultramafic intrusions via magnetic fabric (AMS) and palaeomagnetic studies, Savannah Ni-PGE camp, NW Australia".Tectonophysics 793(2020).