Outer rocky shores of the mowanbini archipelago, devonian reef complex, canning basin, western Australia

Johnson, ME and Webb, GE (2007) Outer rocky shores of the mowanbini archipelago, devonian reef complex, canning basin, western Australia. Journal of Geology, 115 5: 583-600. doi:10.1086/519779

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Author Johnson, ME
Webb, GE
Title Outer rocky shores of the mowanbini archipelago, devonian reef complex, canning basin, western Australia
Journal name Journal of Geology   Check publisher's open access policy
ISSN 0022-1376
Publication date 2007
Sub-type Article (original research)
DOI 10.1086/519779
Open Access Status File (Publisher version)
Volume 115
Issue 5
Start page 583
End page 600
Total pages 18
Place of publication Chicago
Publisher Univ Chicago Press
Language eng
Abstract The Oscar Range in Western Australia's Canning Basin features inliers of folded Paleoproterozoic quartzite, quartzitic conglomerate, and phyllite that formed islands during the Late Devonian. Undisturbed strata of the Pillara Limestone ( Upper Devonian, Frasnian Stage) surround individual paleoislands that rise above the former seabed with a maximum topographic relief of 90 m. On average, the Mowanbini Archipelago ( aboriginal name for the Oscar Range) lies 15 km off the granitic and metamorphic mainland represented by the Kimberley Block to the north. Devonian facies on outer rocky shores were studied at three localities near the southeast end of the Oscar Range. At the west end of the study area, a Devonian reef margin sits unconformably on Paleoproterozoic phyllite, but to the east, the reef is separated from rocky shores by a wide lagoon. Massive clast- supported conglomerate and sandstone beds interfinger with backreef carbonates where the reef is closest to land. Across the lagoon 2.5 km eastward, differential erosion between steeply dipping quartzite layers interbedded with softer phyllite resulted in low sea stacks, or skerries. Tabular quartzite cobbles and quartz sand were shed by the skerries as a unidirectional apron of " breccia" under shoal water conditions. Nearby offshore stromatoporoid thickets reflect growth orientation aligned with paleocurrents compatible with the breccia apron. On a smaller island 2.5 km farther east, lateral transport of debris from a quartzite shore to a contiguous phyllite sector of the coast conforms to the same pattern of water circulation. Overall, the physical geography of outer rocky shores in relation to the lagoon and barrier reef suggests that waves crashed over the reef to energize a longshore current that moved west to east at one end of the Oscar Range. A rapid rise in sea level probably promoted the burial and preservation of the Mowanbini Archipelago, characteristics shared with other examples of quartzite paleoislands that date from Cambrian to Cretaceous times.
Keyword Geology
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Journal Article Import (ISI/CVs)
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 10 times in Scopus Article | Citations
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Created: Mon, 18 Feb 2008, 14:49:17 EST