| Autor: |
Richard Blewett, David C. Champion, P.B. Groenewald, Ben Goscombe, Karol Czarnota, Paul Henson, Kevin F. Cassidy |
| Rok vydání: |
2010 |
| Předmět: |
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| Zdroj: |
Precambrian Research. 183:175-202 |
| ISSN: |
0301-9268 |
| DOI: |
10.1016/j.precamres.2010.08.004 |
| Popis: |
Over the last decade there have been significant advances in our understanding of the stratigraphy, magmatism, deformation, metamorphism and timing of mineralisation, in the eastern Yilgarn Craton (EYC) of Western Australia. The integration of these disciplines has enabled a holistic review of the tectonic history of the EYC which favours a paraautochthonous tectonic model. A significant advance has been the recognition of a ∼2810 Ma rifting event off the eastern margin of the Youanmi Terrane which set up the north-northwest trending architecture of the EYC. Rifting was followed by a ∼100 Myr long phase of tectonic activity initiated by the establishment of a convergent margin at 2715 Ma characterised by a west-dipping subduction zone to the east of the EYC. Subduction was associated with the deposition of 2715–2670 Ma volcanic stratigraphy and the emplacement of voluminous tonalite-trondhjemite-granodiorite magmatism, which resulted in magmatic thickening of the crust. Volcanism was terminated by a ∼5 Myr pulse of east-northeast contraction followed by mid-orogenic extension possibly linked to lithospheric and lower crustal delamination. The lack of ultra-high pressure metamorphism and the presence of high geothermal gradients preclude this contractional event from recording continent–continent collision. Mid-orogenic extension at 2665 Ma resulted in the introduction of metasomatised mantle melts (mafic-granites and syenites), deposition of siliciclastic basins (which record metamorphic anticlockwise PTt paths) and the start of significant economic gold mineralisation in the EYC. High stretching factors and/or delamination associated with this extension event resulted in significant heat input into the base of the crust, which eventually led to the emplacement of Low-Ca (crustal melt) granites and cratonisation of the EYC. Major gold mineralisation postdates mid-orogenic extension, and was associated with renewed compression-transpression (∼2650 Ma) and the development of steep predominantly north-northwest striking sinistral and later north to north-northeast striking dextral strike–slip faults during Low-Ca granite emplacement. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect