Overview of Iskut-Hoodoo area

Our 2017 fieldwork was just the latest installment of research in the Iskut River area over the past 25+ years. A number of studies have been previously done in the area, dating back to the earliest geologic explorers like F.A. Kerr. He travelled up the Iskut River in the earlier parts of the 20th century, and eventually published the first detailed account of the geology of this very remote area in 1948 (Kerr, 1948). Forty years later, starting with Stasiuk and Russell (1991), a program began to study the volcanoes of this area. Work by Edwards and Russell (1993), Edwards et al (1994), Edwards and Russell (2002), Edwards et al. (2002), Hauksdottir et al. (1994) and Russell and Hauksdottir (2000) outlined in more detail history of the local volcanoes (10 in total), including descriptions of the rocks (petrology) and their chemical compositions. A trip into this area involves driving north on Highway 37 to a small stopping spot called Bob Quinn, and then either driving on a controlled access road for 40 km along the Iskut River (with shorter helicopter flight), or flying from Bob Quinn by helicopter (longer flight of about 40 min flight; see map below).

Map showing the region around the lower part of the Iskut River.

Our base camp was nestled in-between two volcanoes: the massive Hoodoo Mountain to the south, and the much small Little Bear Mountain to the north. We were flanked by two outlet/valley glaciers, Hoodoo Glacier to the west, and Twin Glacier to the east. Our fieldwork involved making measurements on both of these two glaciers, in addition to making baseline measurements on top of the ice cap that covers Hoodoo Mountain.

This is truly a land of fire and ice. Glaciers still hang from many of the mountain tops, and the 10 volcanoes in the Iskut volcanic field (see map below) include the large Hoodoo Mountain volcanic center, which is made largely of a relatively uncommon type of lava called ‘phonolite’ and closely related ‘trachyte’. These types of lavas are much more common in the East African Rift, and volcanic islands in the oceans, than in North America. Of course one of the most famous volcanoes in the Antarctic, Mount Erebus, has an active lake of phonolite lava within its summit. Interestingly it is also a glacierized volcano (that means the volcano is right now partly covered by a glacier), as is Hoodoo Mountain. Volcanoes with a lot of evidence in their deposits (pillow lava, palagonitized tuff) of ‘tuyas’.

Map with base from GoogleEarth showing the volcanic centers in the Iskut volcanic field. The red star (Hoodoo) showing more silica-rich volcanic deposits, the blue stars are volcanoes with pillows lavas, and the green areas are ‘normal’ subaerial lavas.

Many of these volcanoes have had eruptions since the end of the last Ice Age (Iskut River, Hoodoo at least), and the Lava Fork lava is probably the youngest volcanic eruption. This lava still has rotting trees that were felled by the eruption rotting on its surface! This makes the Iskut volcanic field one of the most likely places in Canada to have more eruptions in the future.

 

References

*Edwards, BR, Russell, JK (2002) Glacial influence on the morphology and eruption products of Hoodoo Mountain volcano, northwestern British Columbia. In Smellie, J and Chapman, M. (eds) Volcano-Ice Interaction on Earth and Mars, Geological Society of London Special Publication 202, 179-194.

*Edwards, BR, Russell, JK, Anderson RG (2002) Subglacial, phonolitic volcanism at Hoodoo Mountain volcano, northwestern Canadian Cordillera. Bull. Volc., DOI 10.1007/s00445-002-0202-9.

*Edwards, BR, Anderson, RG, Russell JK, Hastings, NL, Guo, YT (2000) Geology of the Quaternary Hoodoo Mountain Volcanic Complex and adjacent Paleozoic and Mesozoic basement rocks; parts of Hoodoo Mountain (NTS 104B/14) and Craig River (NTS 104B/11) map areas, northwestern British Columbia. Geological Survey of Canada, Open File Report 3721, scale 1:20 000.

*Edwards, BR (1997): Field, Kinetic and ThermodynamicStudies of Magmatic Assimilation in the Northern Cordilleran Volcanic Province, Northwestern British Co-lumbia. Ph.D. thesis, Univ. of British Columbia, Vancouver, British Columbia.

*Edwards, BR, Edwards, G, Russell, JK (1995) Revised stratigraphy for the Hoodoo Mountain volcanic center, northwestern British Columbia; In Current Research, part A; GSC Paper 95-1A, 105-115. [8]

*Edwards, BR, Russell, JK (1994) Preliminary stratigraphy for the Hoodoo Mountain volcanic center, northwestern British Columbia; In Current Research, Part A; GSC Paper 94-1A, 69-76.

*Hauksdóttir, S., Enegren, E.G. & Russell, J.K. (1994) Recent basaltic volcanism in the Iskut–Unuk rivers area, northwestern British Columbia. Geol. Surv. Can., Current Res. 1994-A, 57-67.

*Kerr, A. (1948) Lower Stikine and western Iskut River areas, British Columbia. Geol. Surv. Can., Mem. 246.

*Russell, J.K., Hauksdóttir, S. (2000) Estimates of crustal assimilation in Quaternary lavas from the northern Cordillera, British Columbia. The Canadian Mineralogist, v. 39, 275-297.

*Russell, JK, Stasiuk, MV, Page, T, Nicholls, J, Rust, A, Cross, G, Schmok, J, Edwards, BR, Hickson, CJ, Maxwell, M (1998) Radar studies of the Hoodoo icecap, Iskut River region, British Columbia; In Current Research, Part A; GSC Paper 98- 1A.

*Stasiuk, M.V. & Russell, J.K. (1990) Quaternary volcanic rocks of the Iskut River region, northwestern British Columbia. Geol. Surv. Can., Pap. 90-1E, 153-157.

 

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