Metavolcanic Mountain (86°13′S 126°15′W / 86.217°S 126.250°W / -86.217; -126.250) is a large flat-topped mountain rising to 2,480 metres (8,140 ft) some 5 nautical miles (9 km) north of the Hatcher Bluffs on the east side of Reedy Glacier, Antarctica. Composed largely of dark metavolcanic rock, this mountain contrasts with lighter-colored granites surrounding it. It was mapped by the United States Geological Survey from surveys and U.S. Navy aerial photographs, 1960–64. A geologist, J.H. Mercer of the Institute of Polar Studies, Ohio State University, proposed the name after field work in the vicinity of it and Reedy Glacier.[1][2]

Bedrock geology

The bedrock comprising Metavolcanic Mountain consists largely of eponymous metavolcanic rocks. These metavolcanic rocks belomg to the Wyatt Formation. They consist of fragmented grains of quartz and feldspar, and rounded grains of blue quartz (?). The blue quartz grains are highly strained and partially resorbed. A fine-grained, recrystallized matrix of quartz and feldspar, which contains contains varying amounts of biotite and muscovite, surrounds these grains. The fine-grained matrix locally exhibt a strong secondary foliation. The metavolcanic rocks of the Wyatt Formation of Metavolcanic Mountain lack any primary structures and neither their thickness nor their attitude are known.[3][4]

Sr-Ar dating of rocks Wyatt Formation from Metavolcanic Mountain and elsewhere indicates that these rocks were erupted during the Middle Cambrian Epoch. Thus, the Wyatt Formation were erupted at the surface of the Earth or intruded at shallow depth during the active phase of the Ross Orogeny.[4]

The bedrock underlying the northwest tip of Metavolcanic Mountain is mapped as Granite Harbor Intrusives. These granites contain several zones of tourmaline granite. Adjacent to its contact with Granite Harbor Intrusives, quartz veins are commonly exposed in some outcrops of the Wyatt Formation.[3][4]

Surficial geology

A blockfield (felsenmeer) covers surface of Metavolcanic Mountain. The blockfield consists of boulders of dark metavolcanic rocks and scattered glacial erratics of highly weathered, light colored granite. Typically, the density of erratics is very sparse, not more than one to a square kilometer. A concentration of granitic erratics associted with 1 m (3.3 ft) of light-colored silty till containing cobbles of granitic and sedimentary rock occurs on Metavolcanic Mountain at about 2,700 m (8,900 ft) above sea level and 600 m (2,000 ft) above the subjacent surface of the Reedy Glacier.[5]

A sample of this light-colored silty till of the Sirus Group was found to contain abundant foraminifera, diatoms, radiolarians, sponge spicules, ostracodes, and palynomorphs. The foraminifera consist of a mixture of Late Cretaceous and Eocene taxa. The fossil diatoms consist of Late Eocene through late Oligocene and Pliocene taxa. The Pliocene diatom taxa includes Coscinodisais vulnificus, which ranges from 3.1 to 2.2 myr in age. these fossils provide age constraints for the timing of PreQuaternary glaciations of this part of Antarctica.[6]

See also

  • Morales Peak rises from the southern part of Metavolcanic Mountain
  • Mount Pool rises from the northwest side of Metavolcanic Mountain

References

  1. ↑ Stewart, J., 2011. Antarctica: An Encyclopedia, 2nd ed. Jefferson, North Carolina and London, McFarland & Company, Inc. 1771 pp. ISBN 978-0-7864-3590-6
  2. ↑ "Metavolcanic Mountain". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 2023-10-09.
  3. 1 2 Murtaugh, J.G., 1969. Geology of the Wisconsin Range batholith, Transantarctic mountains. New Zealand Journal of Geology and Geophysics, 12(2-3), pp.526-550.
  4. 1 2 3 Faure, G., and Mensing, T. M., 2010. The Transantarctic Mountains Rocks, Ice, Meteorites and Water. Germany, Heidelberg, Springer Dordrecht. 804 pp. ISBN 978-1-4020-8406-5
  5. ↑ Mercer, J.H., 1968. Glacial geology of the Reedy Glacier area, Antarctica. Geological Society of America Bulletin, 79(4), pp.471-486.
  6. ↑ Webb, P.N., Harwood, D.M., McKelvey, B.C., Mercer, J.H. and Stott, L.D., 1984. Cenozoic marine sedimentation and ice-volume variation on the East Antarctic craton. Geology, 12(5), pp.287-291.
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