James Ross Island, situated on the east (Weddell Sea) side of the northern tip of the Antarctic Peninsula (at c. 64°09’S, 57°45’W), is a large basaltic volcano with a shield profile. It has a basal diameter of 35-60 km and a summit (Mt Haddington) at 1500 m and it is the largest volcano by far in the Antarctic Peninsula region, and one of the largest in Antarctica. The island dominates the southern end of a large dispersed volcanic field composed of numerous satellite centres, mainly small monogenetic edifices of glaciovolcanic tuya type, whose products are known as the James Ross Island Volcanic Group (JRIVG). Volcanism commenced at c. 12 Ma, at least, but the oldest products
are known only from stones in interbedded glacial sediments (the JRIVG contains Antarctica’s best-dated terrestrial sedimentary record of Neogene glacial and interglacial events). In situ volcanic outcrops date back to 6.25 Ma and > 50 eruptions are documented. Although eruptions were infrequent, on average occurring every few hundred ka, they were typically large and erupted volumes of tens of km3 are common, making it a Neogene flood basalt volcano. Only alkaline basalts and hawaiites were erupted and there is no obvious compositional variation with time.
Most eruptions were glaciovolcanic and effusive, forming spectacular multiple superimposed pahoehoe lava-fed deltas. The lava-fed deltas are typically 200-400 m thick but examples up to 650 m are present. The thickest comprises the satellite centre known as Dobson Dome on the north side of James Ross Island, which was probably constructed at or close to LGM and may have an erupted volume of c. 80 km3. The JRIVG lava-fed deltas are probably the best studied in the world and have been used to evolve generic models for the construction of glaciovolcanic deltas. They have provided uniquely valuable evidence for temporal variations in the thickness of the Neogene Antarctic Peninsula Ice Sheet.
A few tuff cones are also present and were mostly erupted in a marine setting, presumably during interglacial periods. The largest, forming Terrapin Hill, rises to > 600 m and is at least 6 km in basal diameter. It is one of the largest monogenetic tuff cones in the world and is beautifully exposed.
Because no eruptions have been observed, James Ross Island is generally regarded as inactive. However, the volcanic field is probably still active, as suggested by the very long periods of dormancy (hundreds of ka), several units dated as late Pleistocene (by 40Ar/39Ar) and the presence of two essentially pristine scoria cones on eastern James Ross Island. Conversely, there are no steamfields nor have any marine or cryotephras been discovered with JRIVG compositions and there is no volcano-related seismicity.
CVG Research on James Ross Island:
Construction of a marine emplaced tuff cone and implications for Pleistocene sea levels. James Ross Island is currently essentially inaccessible to new fieldwork due to logistical difficulties.
Key References on James Ross Island:
- Nelson, P. H. H., 1975. The James Ross Island Volcanic Group of north-east Graham Land. British Antarctic Survey Scientific Report 54, 1-62.
- Hole, M.J., Saunders, A.D., Rogers, G., Sykes, M.A., 1995. The relationship between alkaline magmatism, lithospheric extension and slab window formation along continental destructive plate margins. In: Smellie, J.L. (Ed.) Volcanism associated with extension at consuming plate margins. Geological Society, London, Special Publication 81, 265-285.
- Skilling, I. P., 1994. Evolution of an englacial volcano: Brown Bluff, Antarctica. Bulletin of Volcanology, 56, 573-591.
- Skilling, I. P., 2002. Basaltic pahoehoe lava-fed deltas: large-scale characteristics, clast generation, emplacement processes and environmental discrimination. In: Smellie, J.L., Chapman, M.G. (Eds.), Volcano–ice interaction on Earth and Mars. Geological Society, London, Special Publication 202, 91-113.
- Kristjanssen, l., Gudmundsson, M.T., Smellie, J.L., McIntosh, W.C. & Esser, R. 2005. Palaeomagnetic and stratigraphical mapping of Miocene—Pliocene basalts in the Brandy Bay area, James Ross Island, Antarctica. Antarctic Science, 17, 409-417.
- Smellie, J.L. 2006. The relative importance of supraglacial versus subglacial meltwater escape in basaltic subglacial tuya eruptions: an important unresolved conundrum. Earth-Science Reviews, 74, 241-268.
- Smellie, J.L., McIntosh, W.C., Esser, R. & Fretwell, P. 2006. The Cape Purvis volcano, Dundee Island (northern Antarctic Peninsula): late Pleistocene age, eruptive processes and implications for a glacial palaeoenvironment. Antarctic Science, 18, 399-408.
- Smellie, J.L., McArthur, J.M., McIntosh, W.C. & Esser, R. 2006. Late Neogene interglacial events in the James Ross Island region, northern Antarctic Peninsula, dated by Ar/Ar and Sr-isotope stratigraphy. Palaeogeography, Palaeoclimatology, Palaeoecology, 242, 169-187.
- Johnson, J.S. & Smellie, J.L. 2007. Zeolite compositions as proxies for eruptive palaeoenvironment. Geochemistry, Geophysics, and Geosystems, 8, Q03009, doi: 10.1029/2006GC001450.
- Smellie, J.L., Johnson, J.S., McIntosh, W.C., Esser, R., Gudmundsson, M.T., Hambrey, M.J. & van Wyk de Vries, B. 2008. Six million years of glacial history recorded in the James Ross Island Volcanic Group, Antarctic Peninsula. Palaeogeography, Palaeoclimatology, Palaeoecology, 260, 122-148.
- Hambrey, M.J., Smellie, J.L., Nelson, A.E. & Johnson, J.S. 2008. Late Cenozoic glacier—volcano interaction on James Ross Island and adjacent areas, Antarctic Peninsula region. Bulletin of the American Geological Society, 120, No. 5-6, 709-731.
- Smellie, J.L., Haywood, A.M., Hillenbrand, C-D., Lunt, D.J. and Valdes, P.J. 2009. Nature of the Antarctic Peninsula Ice Sheet during the Pliocene: geological evidence & modelling results compared. Earth-Science Reviews, 94, 79-94.
- Nelson, A.E., Smellie, J.L., Hambrey, M.J., Williams, M., Vautravers, M., Salzmann, U., McArthur, J.M. & Regelous, M. 2009. Neogene glacigenic debris flows on James Ross Island, northern Antarctic Peninsula, and their implications for regional climate history. Quaternary Science Reviews, 28, 3138-3160.
- Kosler, J., Magna, T., Mlcoch, B., Mixa, P., Nyvlt, D. & Holub, F.V. 2009. Combined Sr, Nd, Pb and Li isotope geochemistry of alkaline lavas from northern James Ross Island (Antarctic Peninsula) and implications for back-arc magma formation. Chemical Geology, 258, 207-218.