Late Archaean geodynamic processes: how the Eastern Yilgarn Craton evolved in time and space  

Authors / CoAuthors

Czarnota, K. | Champion, D.C. | Goscombe, B. | Blewett, R.S. | Henson, P.A. | Cassidy, K.F. | Groeneweld, B.R.

Abstract

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 Goldfields Superterrane (EGST) of Yilgarn Craton, WA. The integration of these disciplines has enabled a holistic review of the tectonic history of the EGST, thereby providing a para-autochthonous geodynamic context for its mineralisation. A significant advance has been the recognition of a ~2.81 Ga rifting event off the eastern margin of the Youanmi Terrane which set up the north-northwest trending architecture of the EGST, as expressed in the Nd TDM map. Rifting was followed by the establishment of a convergent margin characterised by a west dipping subduction zone to the east of the EGST. Subduction resulted in the deposition of the 2.715-2.67 Ga volcanic stratigraphy and the emplacement of voluminous TTG magmatism, which resulted in magmatic thickening of the crust. Volcanism was terminated by a ~5 Ma pulse of east-northeast contraction which triggering lithospheric and lower crustal delamination associated with mid-orogenic extension. The lack of ultra-high pressure metamorphism and the presence of high geothermal gradients preclude this event from recording a continent-continent collision. Mid-orogenic extension initiated at 2.665 Ga resulted in the introduction of metasomatised mantle melts (Mafic-granites and Syenites), deposition of late-stage siliciclastic basins (which record anticlockwise PTt paths) and the start of significant economic gold mineralisation in the EGST. The delamination associated with this 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 EGST.

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nonGeographicDataset

eCat Id

68825

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Keywords

• External Publication

( Theme )

• geodynamics

( Theme )

• mineral exploration

• AU-WA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2009-04-20T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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unknown

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geoscientificInformation

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Unknown

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[-32.0, -26.0, 120.0, 128.0]

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