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Morphology and propagation styles of Miocene submarine basanite lavas at Stanley, northwestern Tasmania, Australia
Goto, Y and McPhie, J (2004) Morphology and propagation styles of Miocene submarine basanite lavas at Stanley, northwestern Tasmania, Australia. Journal of Volcanology and Geothermal Research, 130 (3-4). pp. 307-328. ISSN 0377-0273
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Miocene submarine basanite pillows, lava lobes, megapillows and sheet lavas in the Stanley Peninsula,
northwestern Tasmania, Australia, are well-preserved in three dimensions. The pillows have ropy wrinkles, transverse
wrinkles, symmetrical wrinkles, contraction cracks and three types of spreading cracks on their surfaces, and
concentric and radial joints in the interior. The lava lobes have ropy wrinkles and contraction cracks on their surfaces.
The megapillows are cylindrical with a smoothly curved upper surface and steep sides, and are characterized by
distinct radial columnar joints in the interior. They are connected to pillows that propagate radially from its basal
margin. The sheet lavas are tabular and have vertical columnar joints in the interior. The largest sheet lava shows a
remarkable gradation from a lower 5-m-thick pillow facies to an upper massive facies. The pillows, lava lobes,
megapillows and sheet lavas are inferred to have been emplaced completely below sea level but in a shallow marine
environment. Their morphological features suggest that the pillows grew by episodic rupture of a near-solid crust and
emergence of hot lava, whereas the lava lobes propagated by continuous stretching of the outer skin at the flow front.
The megapillows and sheet lavas were master feeder channels by which molten lava was conveyed to the advancing
pillows. The sheet lavas propagated by repeated processes of pillow formation and overriding by an upper massive
part. Alternating pillow and massive facies commonly found in ocean-floor drill cores and exposed in cross-section in
many subaqueous volcanic successions may have formed by propagation of pillows from the basal margins of
advancing sheet lavas.
|Keywords:||lava morphology; submarine; pillow; propagation style; basanite|
|Journal or Publication Title:||Journal of Volcanology and Geothermal Research|
|Page Range:||pp. 307-328|
|Identification Number - DOI:||10.1016/S0377-0273(03)00311-1|
The definitive version is available at http://www.sciencedirect.com/
|Date Deposited:||04 Oct 2007 06:46|
|Last Modified:||18 Nov 2014 03:22|
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