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Sedimentology, structure and SHRIMP zircon provenance of the Woodline Formation, Western Australia Implications for the tectonic setting of the West Australian Craton during the Paleoproterozoic [查看] C.E.Hall、S.A.Jones、S.Bodorkos

The Paleoproterozoic Woodline Formation forms a 50 km long, northeast-trending belt of metasedimentary rocks that unconformably overlies Archean granites and greenstones of the Eastern Goldfields Superterrane near the southeastern margin of the Yilgarn Craton. The Woodline Formation is dominated by mature, quartz-rich sandstone units interbedded with siltstones, and represents the remnants of a broader siliciclastic sequence deposited along a passive margin after c. 1737 Ma. The formation is weakly deformed and metamorphosed to lower greenschist facies,with upright northeast-trending folds resulting from northwest–southeast shortening during the Albany–Fraser Orogeny between 1345 Ma and 1140 Ma. An extensional event at c. 1210 Ma is recorded by the emplacement of the northeast-trending Fraser dyke swarm and formation of the grabens that preserved the Woodline Formation. Three hundred and seventy-one U–Pb SHRIMP detrital zircon analyses from six samples from coarse-grained sandstone units of the Woodline Formation indicate a maximum depositional age of 1737±28 Ma (95% confidence). The age data from all six samples show heterogeneity of age spectra from the Eoarchean to the Paleoproterozoic, with an up-sequence diversification of source terranes. Significant probability maxima at 2687 Ma, 2655 Ma and 2629 Ma are consistent with erosion of the underlying Archean granite–greenstone rocks of the Eastern Goldfields Superterrane and the adjacent terranes of the Yilgarn Craton. In comparison, the Paleoproterozoic zircons with maxima at 2245 Ma, 2034 Ma and 1886 Ma do not match known tectonomagmatic events within theWest Australian Craton. Correlation of detrital zircon results from theWoodline Formation with other Paleoproterozoic siliciclastic units around the margin of the Yilgarn reveal a remarkable similarity with the Earaheedy Group, especially with the Paleoproterozoic age peaks indicating a common protosource(s) that is either buried, no longer exists, or is part of an exotic terrane beyond the West Australian Craton.