Geological, Biological, and Chemical Oceanography of the 

 Eastern Central Chukchi Sea^ 



A. S. Naidu - and G. D. Sharma ^ 



GEOGRAPHIC AND GEOLOGIC SETTINGS 



The nearshore environment of the eastern 

 central Chukchi Sea lies west of northwest 

 Alaska (fig. 1). East of Point Barrow this sea 

 merges imperceptibly into the western Beau- 

 fort Sea. The coastline between Point Barrow 

 and Point Lay is very slightly curved, but 

 further south to Cape Lisburne the coast is 

 distinctly embayed. Between Icy Cape and 

 Point Lay a barrier-spit-lagoon-delta complex 

 characterizes the coastline. 



The oceanography of the Chukchi Sea off 

 Alaska's northern coast has not been investi- 

 gated as thoroughly as that portion between 

 the Bering Strait and Cape Lisburne in the 

 southeastern Chukchi Sea. From a few sound- 

 ings made by Moore (1964) and Creager and 

 McManus (1965) it is suggested that the off- 

 shore area between Icy Cape and Point Lay is 

 shallow (<25 m), very flat and featureless. 

 Contrary to this the topography off Point Hope 

 is relatively steep and is characterized by the 

 presence of a submarine valley (Creager and 

 McManus, 1966). In the area we investigated 

 there is a net northward movement of currents 

 over the year (Aagaard and Coachman, 1964), 

 although presence of a local clockwise gyre has 

 been indicated off Cape Lisburne by Fleming 

 and Heggarty (1966). 



The eastern central Chukchi Sea is covered 

 with ice almost 8 months of the year. The 

 climate over this sea and the hinterland is 

 dominated by long severe winters and short 

 cool summers, with a mean annual temperature 

 around 20° F. The average rainfall of 10 inches 

 is comparable to that in arid and semiarid 

 regions. The northwestern coast of Alaska is 



^ Institute of Marine Science, Contribution No. 119. 

 ' Institute of Marine Science, University of Alaska. 



generally windy and storms are not uncom- 

 mon. 



The drainage basin ad,)acent to the eastern 

 central Chukchi Sea coast consists of the 

 Coastal Plain and the Foothill Provinces 

 (Payne et al., 1951) ; the latter pass in the 

 southeast into the Brooks Range. Cape Lis- 

 burne consists of a limestone promontory. The 

 geology of the southern hinterland of the east- 

 ern central Chukchi Sea, extensively studied by 

 Smiley (1969a and 1969b), is composed of the 

 predominantly marine Kukpowruk and non- 

 marine Corwin Formations of Early Albian to 

 possibly Cenomanian age. These rock types are 

 chiefly conglomerates, graywackes, sandstones, 

 shales and limestones, with coal beds confined 

 to the nonmarine formations. In far north- 

 western Alaska the coastal plains are overlain 

 with Quaternary glacial and glacio-fluvial sedi- 

 ments, alluvium and beach deposits. 



METHODS AND MATERIALS 



The geological sampling yielded a suite of 

 107 sediment samples from the nearshore 

 marine environment of the eastern central 

 Chukchi Sea (fig. 1). Of the total samples col- 

 lected, 73 were obtained with a Van Veen 

 and/or Shipek grab sampler, 13 were short 

 cores obtained with a gravity corer, one was a 

 long piston core and 15 were handpicked from 

 the beach surface. The beach samples were 

 taken from a few transects across the barrier 

 in the vicinity of Point Lay to study the nature 

 of arctic barrier beach deposits coincident with 

 the beginning of ice push onto the beaches. 



To minimize metal contamination, the 13 

 gravity core samples were collected in plastic 

 core liners with no metal core barrel or core 

 catcher. The gravity corer was dropped only 

 on stations which had relatively muddy bot- 



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