Morainic Ridge Complex, Eastern Barents Sea

Valery Gataullin 1 and Leonid Polyak2 1 NIl Morgeo, Riga, Latvia; 2Byrd Polar Research Center, Ohio State University, U.S.A.

The seafloor of the eastern Barents Sea west of Novaya Zemlya is characterized by a rough to­pography with a system of elongated holes and ridges reaching 200-300 km in length and 50-100 m in relative height (Figs. 1-2). Most ridges are concentrated in several large, arcuate belts subparallel to the Novaya Zemlya coastline [Epshtein and Gataullin, 1993], similar to mo­rainic ridge belts around the continental mar­gins of Norway and Svalbard [e.g., Vo"en and KristofJersen, 1986). The structure and mor­phology of the ridges suggest that they are marginal moraines, presumably formed by the retreating ice sheet centered over Novaya Zemlya during the deglaciation of the Barents Sea [e.g., Polyak et al., 1995].

Sparker profiles (Fig. 2) exemplify the cross-sections of a large morainic belt (A) and a small isolated ridge (B). Seismic and borehole data show that the ridges are composed of stiff Quaternary diamicton with inclusions of soft Mezosoic bedrock. The diamicton overlies the bedrock with a prominent erosional unconform­ity, known from the western Barents Sea as the Upper Regional Unconformity (URU) [Solheim and KristojJersen, 1984]. The seismic signature of the diamicton is chaotic with short, diversely oriented reflectors (Fig. 2). In topographic depressions, the diamicton is overlain by a thin cover of soft postglacial mud.

Acknowledgments. This publication was made possible in part by Grant LF 1000 from the Intema­tional Science F01Dldation to V. Gataullin.

REFERENCES

Epshtein, O. G., and V. N. Gataullin, Lithology and conditions of formation of QuaternaIy deposits in the eastem part of the Barents Sea (Novaya Zemlya side), Lithology and Mineral Resources (USSR), 28, 84-94, 1993.

Polyak, L., S. 1. Lehman, V. Gataullin, and A 1. T. Jull, Two-step deglaciation of the southeastern Barents Sea, Geology, 23, 567-571, 1995.

Solheim, A, and Y. Kristoffersen, The physical en­vironment, western Barents Sea. Sediments above the upper regional 1Dlconformity: thickness, seismic stratigraphy and outline of the glacial history, Norsk Polarinst. Skrifter 179 B, 26 pp., 1984.

Vorren, T.O., and Y. Kristoffersen, Late Quaternary glaciation in the south-western Barents Sea, Boreas, 15,51-59,1986.

L. Polyak, Byrd Polar Research Center, 1090 Car­mack Rd., Columbus, OH 43210, U.S.A

Figure 1. Overview and study area map with bathymetric contours in meters, location of boreholes (black dots), and the transect on Fig. 2. Dashed lines show major morainic ridges.

82 T. A. Davies et al. (eds.), Glaciated Continental Margins© Chapman & Hall 1997

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A

A

B

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Admiralty Bank

.. , "' ;' I~' , '

~4km

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E

Novaya Zemlya Trough

300

2km ., . 20 ms i]

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Figure 2. Geological transect across the morainic ridge complex based on seismic records and borehole data, with fragments of sparker profiles showing the details of morainic ridge structure. URU - Upper Regional Unconformity. The sparker profiles were performed by the Arctic Marine Geotechnical Expedition (AMIGE, Murmansk, Russia) by means of a SAC-3 seismoacoustic complex with a multi-electrode sparker array; source energy 21d, central frequency 350 Hz, tow depth 1 m.

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