Astoria Fan

45°15′00″N 126°15′00″W / 45.25000°N 126.25000°W / 45.25000; -126.25000

The Astoria Fan is a submarine fan. It has sediment, radiating asymmetrically southward from the mouth of the Astoria Canyon. From Astoria Canyon's mouth, the fan extends about 100 kilometres (62 mi) to its western end, which is the Cascadia Channel. The fan proper ends 160 kilometres (99 mi) south of the canyon mouth, although its depositional basin extends southward another 150 kilometres (93 mi) to the Blanco fracture zone.[1]

Astoria Fan is generally asymmetrical. It extends roughly 55 miles (89 km) west of the mouth of Astoria Canyon, and about 55 miles (89 km) north, to Willapa Channel. Others trace different dimensions.[2]

Headed west, the fan crosses the continental shelf, trending sinuously down to the base of the continental slope. Near Astoria Canyon, it is at a depth of 2,740 metres (8,990 ft). The fan is approximately 75 miles (121 km) long. It varies in width from 1.5 miles (2.4 km) to 8.3 miles (13.4 km).[3] It has numerous tributaries.[4] The fan extends about 100 kilometres (62 mi) to its western boundary, which is the Cascadia Channel.

Ash from the eruption of Mount Mazama has been found, in Astoria Fan.[1] It may have been cut in the Pleistocene.[4] It appears the Missoula Floods helped carve the fan.[5]

Astoria Fan merges into Astoria Canyon, 9 miles (14 km) west of the Columbia River mouth. In the past, buried Pleistocene channels appear to have connected the two.[4]

Nearby submarine canyons

All of the following submarine canyons are near, headed north to south:[6][7]

See also

Local geography

References

  1. ^ a b C. Hans Nelson (1985). "Astoria Fan, Pacific Ocean". Submarine Fans and Related Turbidite Systems. Frontiers in Sedimentary Geology. Springer. pp. 45–50. doi:10.1007/978-1-4612-5114-9_8. ISBN 978-1-4612-9570-9.
  2. ^ Cartlon, Hans (1968). "Marine Geology of Astoria Deep-Sea Fan" (PDF). Oregon State University. Retrieved 2017-09-19.
  3. ^ Nelson, C. Hans (December 6, 1982). "The Astoria Fan: An elongate type fan" [The Astoria Fan: An elongate type fan]. Geo-Marine Letters. 3 (2–4): 65–70. doi:10.1007/BF02462449. S2CID 131111461.
  4. ^ a b c C.H. Nelson, P.R. Carlson, J.V. Byrne, and T.R. Alpha (1970). "Development of the Astoria Canyon-Fan physiography and comparison with similar systems". Marine Geology. 8 (3–4): 259–291. Bibcode:1970MGeol...8..259N. doi:10.1016/0025-3227(70)90047-2. Retrieved 18 September 2017.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ Embley, Bob (June 9, 2010). "Astoria Canyon: A Natural Laboratory". NOAA. Retrieved 2017-09-19.
  6. ^ Steelquist, Robert (July 26, 2017). "Seafloor". NOAA. Retrieved 23 August 2017.
  7. ^ "Exploring Olympic Coast National Marine Sanctuary & Quinault Canyon". Nautilus Live. August 17, 2017. Retrieved 19 September 2017.