Sathy Naidu

The Late Quaternary Flow through the Bering Strait Has Been Forced by the Southern Ocean Winds

Because North and South America are surrounded by water, they constitute together a gigantic island whose peripheral sea level is controlled by the winds east of the island, winds along the western boundary of the island, the freshwater flux, and the meridional overturning cell. This idea has been expressed in several articles where a series of analytical models show that the Bering Strait (BS) flow is controlled by the interplay of the Southern Winds (sometimes referred to as the ‘‘Subantarctic Westerlies’’), and the North Hemisphere freshwater flux. Here, the authors report a paleoceanographic analysis of proxies in the BS as well as the Southern Ocean, which clearly support the above through employment of a slowly varying time-dependent version of the coupled Sandal–Nof model. This study shows a very strong correlation between the Southern Ocean winds and the BS flow. A midHolocene weakening of the Southern Winds followed by the cession of freshwater fluxes from the melting Laurentide ice sheet strengthened the BS flow for several thousand years. Increasing the Southern Winds enhances the near surface, cross-equatorial flow from the Southern Ocean to the Northern Hemisphere. This cross-equatorialflowdecreasestheArcticoutflowintotheAtlanticdemonstratingadynamiclinkagebetween the Southern Ocean Winds and the mean flow through the BS.

GIS Based Marine Platinum Exploration, Goodnews Bay Region, Southwest Alaska

Goodnews Bay, southwest Alaska, is known for platinum (Pt) reserve that extends offshore in the Bering Sea. To assess the nearshore placer potential we first collated marine Pt concentrations available since 1960 in a geographic information system (GIS) database. Subsequently, in 2005, we collected 23 pipe dredge sediment samples and 26 vibracores from unexplored sites and analyzed them for Pt. This sampling was supplemented by magnetic (Sea Spy) and seismic (side scan, geoacoustic and datasonic bubble pulser) surveys. Integrating results of geospatial analysis of Pt concentrations with geophysical analysis using GIS techniques led to delineate four locations encouraging for further Pt exploration. Of these, two locations fall close to paleochannels and drowned ultramafic source, while the other two coincide with high energy environments in the Goodnews Bay and close to the Carter Bay.

Exploration and Estimation of Gravel Resource Potential in Southeast Chukchi Sea Continental Shelf off Kivalina, Alaska

Frequent storm surges in the Alaskan arctic result in washovers and high erosion of barrier islands. The village council of Kivalina has resolved to relocate its present location on a barrier island in northwest arctic Alaska to an adjacent onshore site. The relocation plan envisages excavation of the upper 4 meters of the 25-km2 onshore permafrost ground and the construction of a foundation pad. The objective of this research is to estimate the gravel resource potential in the continental shelf off Kivalina. In this context, seismic surveys and sediment sampling were conducted. The seismic surveys were of limited use as they failed to resolve the upper 1–2 m of the seafloor. The lithostratigraphy indicated dominance of the 2.4–3.4 mm size fraction in the region north of Kivalina. The geostatistical analysis indicated an omnidirectional variogram fit to the data with ordinary kriging (OK) producing the best kriging estimate of the gravel resource potential. At least 20 × 106 m3 of gravel above 90% cut-off is present in the upper 0.5 m of the seafloor. The regional Pleistocene glaciation has affected the lateral variations in gravel abundance in the nearshore southeast Chukchi Sea.