Mawson Formation

Mawson Allan Hills Coombs Hills Prince Albert Mtns., in southern Victoria Land 

Prebble Queen Alexandra Range Otway Massif Grosvenor Mtns., in the central Transantarctic Mountains 

Exposure Hill Mesa Range and nearby nunataks Deep Freeze Range northern Victoria Land 

The phreatomagmatic origin of the Mawson Formation, demonstrated by White and McClintock (2001), was caused by explosions in the subsurface when large amounts of water interacted with basalt magma that had entered rifts in the basement of the Transantarctic Mountains. The water that caused the phreatomagmatic explosion originated primarily from pore water in the Beacon sandstones. In addition, rift valleys that may have formed at the surface may have 

White and McClintock (2001) divided the breccia pipe (or diatreme) in Fig. 12.5 into three sections which they identified as  

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The Exposure Hill Formation of northern Victoria Land occupies the same stratigraphic position as the Mawson Formation in the Allan and Coombs hills of southern Victoria Land. Both formations are composed of volcanic breccias and related pyroclastic rocks that formed at the start of the eruption of the Kirkpatrick Basalt and the intrusion of sills of the Ferrar Dolerite of the Middle Jurassic Ferrar Group which is the subject of Chapter 12. 

Fig. 12.4 The Allan Hills and Coombs Hills at the edge of the polar plateau in southern Victoria Land expose the Mawson Formation as well as the underlying formations of the Beacon Supergroup and the overlying Kirkpatrick Basalt and Ferrar Dolerite sdUs. The Mawson Formation consists of laharic deposits and volcanic breccias interbedded with layers of tuffaceous sandstone. This formation represents a transition from felsic pyroclastics, that characterize the Triassic Lashly Formation, and the large-scale eruption of tholeiitic baseilt in Gondwana during the Jurassic (Adapted from ElUot et til. 2006)...

White and McClintock (2001) considered that the root zone of a phreatomagmatic diatreme can migrate sideways as a result of multiple explosions that shatter the country and thereby expand the root zone. This process can enlarge the volume of brecciated country and cause additional diatremes to form. Accordingly, the Mawson Formation in the Coombs Hills consists of... 

The Mawson Formation in the Coombs HiUs is locally overlain by the Kirkpatrick Basalt and was intruded by dikes and sills of the Ferrar Dolerite. This evidence could mean that the Mawson Formation predates the Ferrar Group. However, the presence of basalt and dolerite clasts in the Mawson Diamictite indicates that basalt was already erupting and that sills of dolerite had already intruded the underlying Beacon rocks when the phreatomagmatic explosions occurred. Therefore, the Mawson Formation is part of the Ferrar... 

Elliot DH (2000) Stratigraphy of Jurassic pyroclastic rocks in the Transantarctic Mountains. J African Earth Sd 31 77-89 Elliot DH (2002) Paleovolcanological setting of the Mawson Formation Evidence from the Prince Albert Mountains, Victoria Land. In Gamble JA, Skinner DNB, Henrys S (eds) Antarctica at the close of the Millennium. The Royal Society of New Zealand Bulletin, vol. 35. Wellington, New Zealand, pp 185-192... 

Clasts of diamictite of the Mawson Formation which is exposed in the Allan and Coombs hills (Section 12.3.1) occur at 60% of the surveyed sites at abundances greater than zero but less than about 8% by number in Fig. 17.7c. The abundances of... 

Mawson, S. Johnston, K. P. Combes, J. R. DeSimone, J. M. Formation of Poly(l,l,2,2-tetrahydroperfluorodecyl acrylate) Submicron Fibers and Particles from Supercritical Carbon Dioxide Solutions. Macromolecules 1995, 28, 3182-3191. 

Mawson S, Johnston KP, Combes JR et al (1995) Formation of poly(l,1,2,2-tetrahydroperfluorodecyl acrylate) submicron fibers and particles from supercritical carbon dioxide solutions. Macromolecules 28(9) 3182—3191... 

Fig. 12.2 Outcrop of Mawson Diamictite in the Allan HUls. The rocks of this formation are unstratified and are composed of dolerite and sandstone clasts in a fine-grained matrix that contains zeolites and other products of hydrothermal alteration (Photo by G. Faure)...

Section Peak Formation. Therefore, the breccias of the Exposure Hill Formation could have formed as a result of phreatomagmatic explosions in the subsurface like those that produced the Mawson Diamictite in the Coombs Hills (White and McClintock 2001). 

BaUance P, Watters WA (1971) The Mawson Diamictite and the Carapace Sandstone formations of the Ferrar Group at Allan Hills and Carapace Nunatak, Victoria Land, Antarctica. New Zealand J Geol Geophys 14 512-527... 

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