Tsunami deposits on a paleoproterozoic unconformity? The 2.2 ga yerrida marine transgression on the northern margin of the Yilgarn Craton, Western Australia

Desmond F. Lascelles, Ryan J. Lowe

Research output: Contribution to journalArticlepeer-review

Abstract

Large blocks and boulders of banded iron formations and massive hematite up to 40 × 27 × 6 m³ and in excess of 10,000 metric tonnes were detached from an outcrop of the Wilgie Mia Formation during the ca 2.20 Ga marine transgression at the base of the Paleoproterozoic Windplain Group and deposited in a broad band on the wave-cut surface 900 to 1200 m to the east. At the same time, sand and shingle were scoured from the sea floor, leaving remnants only on the western side of the Wilgie Mia Formation and on the eastern sides of the boulders. Evidence suggesting that the blocks were detached and transported and the sea floor scoured by a tsunami bore with a height of at least 40 m is provided by the following: (1) the deposition of the blocks indicates transportation by a unidirectional sub-horizontal force, whereas the smaller boulders are randomly oriented; (2) 900–1200 m separates the banded iron formation (BIF) outcrop and the blocks (3) there is an absence of the basal conglomerate between the blocks; (4) the blocks and boulders rest directly on the wave-cut surface of deeply weathered amphibolites; (5) the blocks and boulders are surrounded and over-lain by fine-grained sandstone of the Windplain Group.

Original languageEnglish
Article number213
Pages (from-to)1-19
Number of pages19
JournalJournal of Marine Science and Engineering
Volume9
Issue number2
DOIs
Publication statusPublished - Feb 2021

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