Although there are abundant paleomagnetic data for the circum-arctic cratons, there are few data, at least in the open literature, from rocks at the immediate margins of the Arctic Ocean. Most of the published work comes from Spitzbergen and surrounding islands, Ellesmere and nearby islands in Arctic Canada (Wynne et al., 1983), and from the Brooks Range and North Slope in Alaska (Harbert et al., 1990). Some summary paleomagnetic data are also available from the Soviet Union (Kharmov, 1989a, b), but with a few notable exceptions, insufficient supporting data are provided to assess the likelihood of magnetic overprinting. Such assessment is needed because pervasive overprinting has been found in the Alaskan Arctic.

A common problem in making paleomagnetic studies in both modern and ancient high arctic rocks is the steep inclination of the earth's magnetic field, which degrades declination measurements. The steep inclination, and the fact that many key localities have complex reformational histories that introduce uncertainties in restoring paleohorizontal indicators to modern horizontal, have led many investigators to rely more on paleolatitude than on paleomagnetic pole positions (Stone, 1989). Fortunately, most tectonic reconstructions of the Arctic imply paleolatitude changes well within the resolution of the paleomagnetic technique.

The movement of the major circum-arctic cratons has been defined fairly well from paleomagnetic measurements and seafloor magnetic anomalies, but the motions of the smaller crustal fragments nearer the margins of the Arctic Ocean Basin are largely unconstrained. Because many arctic tectonic models make different predictions concerning plate translations and rotations, they are especially amenable to paleomagnetic testing. For example, the displacements of the paleomagnetic poles that would have occurred had large parts of Chukotka and Alaska rotated about a pivot in the Mackenzie Delta area are quite different from those required by translation of Chukotka-Alaska from a location adjacent to the Lomonosov Ridge (Halgedahl and Jarrard, 1987). A paleomagnetic sampling program in the circum-arctic rim to test major tectonic hypotheses for the arctic region and to provide critical benchmarks for constructing new or revised hypotheses is therefore proposed. Initial investigations should also include the Mesozoic rocks of the New Siberian Islands that are key to rotational models for the Arctic and the assorted lithotectonic terranes and ancient island are sequences that lie between the Siberian shield and nuclear North America. The latter samples would test and help to resolve the timing of the postulated isolation of the Arctic from the Pacific Ocean in Late Mesozoic time.

Teleseismic studies offer considerable potential for study of the tectonics and deep crustal structure of the Arctic Ocean Basin and can provide continuous remote monitoring of current tectonic activity (e.g., Fujita et al., 1990). The acquisition of high-quality seismological data from the Arctic is hampered, however, by a lack of seismic stations near the coast and by the low quality of the few existing stations. In addition, few accessible standardized seismic data are available from the large Soviet sector of the Arctic. These factors have resulted in a relatively high detection threshold, about m_b > 4.5 for earthquakes in the central Arctic Ocean and have limited our ability to conduct detailed tectonic and structural studies of this seismogenic region. This handicap would be removed if a permanent network of modern broad-band digital stations were installed in boreholes at coastal stations and islands around the Arctic Rim. Borehole instruments are needed in the Arctic to reduce noise from seasonal melting and freezing of permafrost. The network should feature standardized formats to facilitate the transfer of earthquake data to researchers worldwide.

The continuous record of seismicity that such a network would compile would be especially useful for studying the central Arctic Ocean Basin, where seismogenic structures appear to generate low-to moderate-magnitude earthquakes with long recurrence intervals. The network would greatly improve understanding of the structure and rheology of the crust and upper

Front Matter (R1-R12)

Executive Summary (1-4)

1 Introduction (5-6)

2 Physiography (7-8)

3 Role of the Arctic in Global Solid-Earth Geoscience (9-13)

4 Rationale for Focusing on the Arctic Ocean Basin and Its Margins (14-18)

5 The Next Stage of Arctic Solid-Earth Geoscience Research (19-45)

6 Logistic Realities and Opportunities (46-55)

7 Research Priorities (56-58)

8 Special Concerns (59-60)

References (61-67)