DOI: 10.6084/m9.figshare.20445906
title: Stratigraphy of the Agnew-Wiluna Greenstone Belt: review, synopsis and implications for the late Mesoarchean to Neoarchean geological evolution of the Yilgarn Craton

description: Our ability to understand the geological evolution of Archean cratons is fundamentally dependent on stratigraphic reconstructions across greenstone belts. Here, we integrate published stratigraphic, geochemical and geochronological data to produce a revised stratigraphic model for the Agnew-Wiluna Greenstone Belt of the Yilgarn Craton. The Agnew-Wiluna Greenstone Belt records <i>ca</i> 130 m.y. of magmatism that occurred between <i>ca</i> 2820 and 2690 Ma and can be divided into three cycles. Cycle 1 is marked by <i>ca</i> 2820–2740 Ma mafic–ultramafic volcanic rock successions. Cycle 2 is associated with <i>ca</i> 2740–2720 Ma felsic volcanic rocks, associated fragmental deposits and contemporaneous mafic–ultramafic intrusions. Cycle 3 consists of <i>ca</i> 2720–2690 Ma mafic–ultramafic volcanic rock successions and co-magmatic intrusions. Exhumation and reworking of these continental rift basin successions after <i>ca</i> 2690 Ma resulted in two younger, additional, depositional cycles in the Agnew-Wiluna Greenstone Belt. Cycle 4 is associated with intermediate to felsic volcanoclastic rocks and epiclastic rocks erupted/deposited between <i>ca</i> 2690 and 2665 Ma. Cycle 5 is associated with the deposition of polymict conglomerates and sandstones in localised depocentres between <i>ca</i> 2665 and 2655 Ma. The stratigraphic scheme identified at the scale of the Agnew-Wiluna Greenstone Belt is the local expression of craton-wide tectono-thermal events. Our revised stratigraphic model for the Agnew-Wiluna Greenstone Belt and proposed correlations at the craton scale support a para-autochthonous model whereby crust from a proto-Yilgarn continental mass was extended/thinned, favouring the activation of translithospheric pathways associated with the <i>ca</i> 2720–2690 Ma Kalgoorlie Large Igneous Province. Inversion of this intra-cratonic rift basin after <i>ca</i> 2680 Ma led to the protracted activation of shear zones and multiple shifts in sedimentary depocentres. The widespread occurrence of previously unidentified fragments of <i>ca</i> 2820–2720 Ma substrate within the Kalgoorlie-Kurnalpi Rift has significant implications for craton-scale stratigraphic reconstructions and challenges existing terrane and domain boundaries. KEY POINTSWe propose a revised, coherent and testable stratigraphic model for the Agnew-Wiluna Greenstone Belt of the Kalgoorlie Terrane.We compare our revised stratigraphic model for the Agnew-Wiluna Greenstone Belt with that of the Murchison and Southern Cross domains of the Youanmi Terrane in order to build a new space–time–integrated stratigraphic cross-section across the western half of the Yilgarn Craton.We demonstrate for the first time the existence of a magmatic continuum (<i>i.e.</i> no significant magmatic hiatus) between <i>ca</i> 2820 and 2690 Ma, providing the missing link between the geological record of the Youanmi Terrane and that of the Eastern Goldfields Superterrane. We propose a revised, coherent and testable stratigraphic model for the Agnew-Wiluna Greenstone Belt of the Kalgoorlie Terrane. We compare our revised stratigraphic model for the Agnew-Wiluna Greenstone Belt with that of the Murchison and Southern Cross domains of the Youanmi Terrane in order to build a new space–time–integrated stratigraphic cross-section across the western half of the Yilgarn Craton. We demonstrate for the first time the existence of a magmatic continuum (<i>i.e.</i> no significant magmatic hiatus) between <i>ca</i> 2820 and 2690 Ma, providing the missing link between the geological record of the Youanmi Terrane and that of the Eastern Goldfields Superterrane.