Unit Name: Hazelton Group
Unit Type: Lithostratigraphic
Rank: Group
Status: Formal
Usage: Currently in use
Age Interval: Middle Jurassic - Late Jurassic (175.6 - 145.5 ma)
Age Justification: Tipper and Richards redefined the Hazelton Group to include Early and Middle Jurassic (Sinemurian to early Callovian) strata (Tipper and Richards, 1976).
Province/Territory: British Columbia

Originator: Leach, 1910; revised by Tipper and Richard, 1976, revised by Marsden and Thorkelson, 1992.

Type Locality:
There is no type section that defines the Hazelton Group (Tipper and Richards, 1976).

Distribution:
On the Stikine Terrane (Stikinia), the largest accreted terrane in British Columbia (2000 x 300 km) widespread Lower to Middle Jurassic volcanic and related sedimentary rocks are known as the Hazelton Group. The Hazelton Group is exposed throughout much of central and northern stikinia, extending for approximately 800 km in a semicontinuous belt from latitude 51°N to latitude 58°30'N, and across the entire width of the Stikinia (Wheeler and McFeely, 1987) (Marsden and Thorkelson, 1992; Thorkelson et al., 1995).

Lithology:
Volcanic and related sedimentary rocks (Marsden and Thorkelson, 1992).

Relationship:
Tipper and Richards (1976) and Woodsworth et al. (1985) recognized three formations in the Terrace, Smithers, Hazelton, and McConnell Creek areas. They are, from oldest to youngest, the Telkwa Formation, Nilkitkwa Formation (Carruthers, Ankwell, and Red Tuff members), and Smithers Formation (Yuen and Bait members). In the Whitesail Lake area south of the Smithers area, Hazelton-age rocks have been correlated with the Telkwa and Smithers formations (Tipper, 1979; Diakow and Mihalynuk, 1987; Diakow and Koyanagi, 1988). Rocks equivalent in age to the Nilkitkwa Formation have not been recognized. East of the Whitesail area, in the Nechako River area, the Hazelton Group consists of a generally marine sequence of rhyolitic to basaltic lava and fragmental volcanic rocks intercalated with various sedimentary rocks (Tipper, 1963). From the Bella Coola area, to the south, Baer (1973) described a succession of lava, breccia, and marine sedimentary rocks bearing early Bajocian ammonites. Northwest of Smithers, in the Iskut River, Bowser Lake and Nass River areas, the Hazelton Group is divided into four formations (Grove, 1986; Brown, 1987; Britton and Alldrick, 1988; Anderson and Thorkelson, 1990). They are, from oldest to youngest, the Unuk River Formation, Betty Creek Formation, Mount Dilworth Formation, and Salmon River Formation. Farther to the north, in the Telegraph Creek area, Souther (1972) divided a succession of predominantly marine volcanic and sedimentary rocks into three units (from oldest to youngest, units 13, 14, and 15). In northwestern Telegraph Creek, Brown et al. (1990) described a sequence of four Hazelton Group units with striking similarities to strata in the Iskut River area. They suggested correlations with the Salmon River and Mount Dilworth formations. Their lowest unit may be equivalent to nonmarine facies of the Unuk River or Betty Creek formations. In the Spatsizi River area, east of Telegraph Creek, three temporally distinct volcanic successions occupy a northwest trending belt between the Bowser Basin and Sustut Basin (Gabriesle and Tipper, 1984; Thomson et al., 1986; Evenchick, 1986, 1987; Thorkelson, 1988, 1992; Read and Psutka, 1990). They are, from oldest to youngest, the Griffith Creek volcanics, Cold Fish Volcanics, Spatsizi Group, Mount Brook volcanics, and Quock Formation. In the Toodoggone area, to the southeast of the Cry Lake area Hazelton rocks were informally divided by Carter (1972) into the western sequence which he named the Toodoggone volcanics, and an eastern sequence considered to consist of undivided Hazelton Group rocks. Subsequently, stratigraphic nomenclature has been refined (e.g., Diakow, 1985; Diakow et al., 1991; Marsden, 1990) such that the Toodoggone volcancis are now informally regarded as the Toodoggone formation and seven constituent volcanic members (from oldest to youngest, the Adoogacho, Moyez, Metsantan, McClair, Attycelley, Saunders, and Theban members) (Marsden and Thorkelson, 1992).

History:
Leach (1910) discontinued the use of Porphyrite Group in the Smithers and Hazelton areas and introduced two new names. The Hazelton Group was described as a Jurassic Group, with volcanic rocks at its base near Telkwas, that passed northward in a gradual transition to sedimentary rocks near Hazelton. The Skeena Series was considered to be a sedimentary Lower Cretaceous unit characterized by coal and resting unconformably on the Hazelton Group. Leach generally experienced no difficulty in recognizing the Skeena Series, particularly near Telkwa, but near Hazelton there was difficulty in separating the unit from sediments of the Hazelton Group. For the next thirty-five years, these two stratigraphic units were accepted by most geologists in the Smithers-Hazelton region. However, their definition was vague and interpretations varied. Sections that could be shown to be probably Jurassic were commonly included in the Hazelton Group. An Early Cretaceous age or the presence of coal commonly labelled a section of sediments as the Skeena Series. As a result, confusion with Hazelton Group sediments was a problem, particularly where Hazelton Group beds contained coal, however thin and discontinuous. In 1944 Armstrong (1944a, 1994b) included the Skeena Series with the Hazelton Group as he felt that no stratigraphic division could be made between the two. The Skeena Series as a stratigraphic name was abandoned. The Hazelton Group was accepted and applied to rocks far removed from the Hazelton area and became firmly entrenched in the literature. Hanson (1925) divided the group into three units: a Lower Volcanic Division, a Sedimentary Division with Middle Jurassic fossils, and an Upper Volcanic Division. Jones (1926) accepted Hanson's three divisions and added a fourth, an Upper Sedimentary Division. Armstrong (1944a, 1944b) proposed a fivefold subdivision of the Mesozoic rocks of the Hazelton area, namely: (1) a pre-Middle Jurassic volcanic division; (2) a middle Jurassic marine sedimentary division; (3) a Middle or Upper Jurassic volcanic division; (4) an Upper Jurassic or Lower Cretaceous marine and continental sedimentary division; and (5) a Lower Cretaceous or later volcanic division. In 1960 Sutherland Brown (1960) gave the names Red Rose Formation and Brian Boru Formation to Armstrong's upper two divisions of the Hazelton Group, the Lower Cretaceous sediments and the Cretaceous volcanics, respectively. Even with all these refinements, however, the Hazelton Group has remained an imprecise stratigraphic Jurassic-Cretaceous "catch-all" term (Tipper and Richards, 1976). Jurassic stratigraphic nomenclature in north central British Columbia was clarified by Tipper and Richards (1976, p. 5), who redefined the Hazelton Group as "...basaltic to rhyolitic volcanic rocks, sedimentary rocks, their tuffaceous equivalents, and minor limestone that were deposited in Early and Middle Jurassic (Sinemurian to early Callovian) (Marsden and Thorkelson, 1992). The definition proposed by Tipper and Richards (1976) is more restricted than that envisaged by Leach (1910) because it excludes Middle Jurassic and mid-Cretaceous strata now included within the Bowser Lake and Skeena Groups (Tipper and Richards, 1976). Since then, many geologists working in Mesozoic rocks of northern and central British Columbia have adopted that terminology. Marsen and Thorkelson (1992) concur and broaden that description by defining the Hazelton Group as all Lower to Middle Jurassic volcanic and related sedimentary rocks on Stikinia, south of about 58°30'N. This definition is designed to include basinal sedimentary equivalents of the volcanic successions and to exclude distal strata whose origin is generally unrelated to Hazelton volcanism. It is also consistent with a suggestion by H. W. Tipper (personal communication, 1991) that the top of the Hazelton Group should be placed at the end of early Bajocian time. The degrees to which a given sedimentary succession is tomporally, spatially, and lithologically associated with volcanism are the criteria upon which its inclusion in the Hazelton should be based (Marsden and Thorkelson, 1992).

References:
Anderson, R.G. and Thorkelson, D.J., 1990. Mesozoic stratigraphy and setting for some mineral deposits in Iskut River map area, northwestern British Columbia; in Current Research, Part E; Geological Survey of Canada, Paper 90-1E, p. 131-139.
Armstrong, J.E., 1944a. Preliminary map, Smithers, British Columbia; Geological Survey of Canada, Paper 44-23, scale 1:126 720.
Armstrong, J.E., 1944b. Preliminary map, Hazelton, British Columbia; Geological Survey of Canada, Paper 44-24, scale 1:126 720.
Baer, A.J., 1973. Bella Coola-Laredo Sound Map Areas, British Columbia; Geological Survey of Canada, Memoir 372, 119 pages, plus maps.
Britton, J.M. and Alldrick, D.J., 1988. Sulphurets Map Area; in Geological Fieldwork 1987, British Columbia Ministry of Energy, Mines and Petroleum Resources, Paper 1988-1, pp. 199-209.
Brown, D.A., 1987. Geological setting of the volcanic hosted Silbak Premier mine, northwestern British Columbia (104A/4, B/1); M.Cs. thesis, University of British Columbia, Vancouver.
Brown, D.A., Greig, C.J., and Gunning, M.H., 1990. Geology of the Stikine River-Yehiniko Lake area, northwestern British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Open File 1990-1.
Carter, N.C., 1972. Toodoggone River Area; in Geology, Exploration and Mining in British Columbia, B.C. Ministry of Energy, Mines and Petroleum Resources, p. 63-70.
Diakow L.J., 1985. Potassium-argon age detreminations from biotite and hornblende in Toodoggone volcanic rocks; British Columbia Ministry Energy, Mines Petroleum Research Geological Fieldwork 1984, p. 298-300.
Diakow, L.J. and Koyanagi, V., 1988. Stratigraphy and Mineral Occurrences of Chikamin Mountair and Whitesail Reach Map Areas; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1987, Paper 1988-1, pages 155-168.
Diakow, L.J. and Mihalynuk, M., 1987. Geology of the Whitesail Reach and Troitsa Lake Areas; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1986, Paper 1987-1, pages 171-179.
Diakow, L.J., Panteleyev, A., and Schroeter, T.G., 1991. Jurassic epithermal deposits in the Toodoggone River area, Northern British Columbia: Examples of well-preserved, volcanic-hosted, precious metal mineralization; Economic Geology, v. 86, p. 529-554.
Evenchick, C.A., 1986. Structural style of the northeast margin of the Bowser Basin, Spatsizi map area, north-central British Columbia; in Current Research, Part B, Geological Survey of Canada, Paper 86-1B, pages 733-739.
Evenchick, C.A., 1987. Stratigraphy and Structure of the Northeast Margin of the Bowser Basin, Spatsizi Map Area, Northcentral British Columbia; in Current Research, Part A, Geological Survey of Canada, Paper 87-1A, pages 719-726.
Gabrielse, H. and Tipper, H.W., 1984. Bedrock geology of Spatsizi map area (104 H); Geological Survey of Canada, Open File 1005, scale 1:250 000.
Grove, E.W., 1986, Geology and mineral deposits of the Unuk River-Salmon River-Anyox area. British Columbia Ministry of Energy, Mines and Petroleum Resources, Bulletin 63, 434 p.
Hanson, G., 1925. Driftwood Creek Map-area, Babine Mountains, British Columbia; Geological Survey of Canada, Summary Report 1924, Part A.
Jones, R.H.B., 1926. Geology and Ore Deposits of Hudson Bay Mountain, Coast District, B.C.; Geological Survey of Canada, Department of Mines, Summary Report, 1925, Part A, pages 120A-143A.
Leach, W.W., 1910. The Skeena River district; Geological Survey of Canada, Summary Report 1909.
Marsden, H., 1990. Stratigraphic, structural and tectonic setting of the Shasta Au-Ag deposit, north-central British Columbia; Unpublished M.Sc. thesis, Carleton University, Ottawa, Ontario.
Marsden, H., and Thorkelson, D.J., 1992. Geology of the Hazelton volcanic belt in British Columbia; implications for the Early to Middle Jurassic evolution of Stikinia: Tectonics, v. 11, p. 1266-1287.
Read, P.B. and Psutka, J., 1990. Geology of the Ealue Lake east-half (104H/13E) and Cullivan Creek (104H/14) map areas, British Columbia; Geological Survey of Canada, Open File 2241.
Souther, J.G., 1972. Telegraph Creek map-area, British Columbia; Geological Survey of Canada, Paper 71-44, 39p.
Sutherland Brown, A., 1960. Geology of the Rocher Deboule Range; B.C. Ministry of Energy, Mines and Petroleum Resources, Bulletin 43, 78 pp.
Thomson, R.C., Smith, P.L., and Tipper, H.W., 1986. Lower to Middle Jurassic (Pliensbachian to Bajocian) stratigraphy of the northern Spatsizi area, north-central British Columbia; Canadian Journal of Earth Sciences, v. 23, p. 1963-1973.
Thorkelson, D.J., 1988. Jurassic and Triassic volcanic and sedimentary rocks in the Spatsizi map-area, north-central British Columbia; in Current Research, Part E; Geological Survey of Canada, Paper 88-1E, p. 43-48.
Thorkelson, D.J., 1992. Volcanic and tectonic evolution of the Hazelton Group in Spatsizi River (104H) map-area, North-Central British Columbia, Ph.D. thesis, pp. 1-281, Carleton University, Canada.
Thorkelson, D.J., Mortensen, J.K., Marsden, H. and Taylor, D.C., 1995. Age and tectonic setting of Early Jurassic episodic volcanism along the north eastern margin of the Hazelton Trough, northern British Columbia; in Jurassic Magmatism and Tectonics of the North American Cordillera, D.M. Miller and C.J. Busby (ed.); Geological Society of America, Special Paper 299, p. 83-94.
Tipper, H.W. and Richards, T.A., 1976. Jurassic stratigraphy and history of North-central British Columbia; Geological Survey of Canada, Bulletin 270, 73 p.
Tipper, H.W., 1963. Nechako River map-area, British Columbia; Geological Survey of Canada, Memoir 324, 59 p. Contains "A" Series map no. 1131A, Scale 1:253,440.
Tipper, H.W., 1979. Jurassic Stratigraphy of the Whitesail Lake Map Area, British Columbia; in Current Research, Part A, Geological Survey of Canada, Paper 79-1, pages 31-32.
Wheeler, J.O. and McFeely, P., 1987. Tectonic assemblage map of the Canadian Cordillera; Geological Survey of Canada Open File 1565.
Woodsworth, G.J., Hill, M.L., and van der Heyden, P., 1985. Preliminary Geologic Map of Terrace (NTS 103I, East Half) Map Area, British Columbia; Geological Survey of Canada, Open File 1136, scale 1:125 000.

Source: LEXICON_BC
Contributor: Michael Pashulka
Entry Reviewed: No
Name Set: Lithostratigraphic Lexicon
LastChange: 20 Jan 2011