Geological effects of the Gulf Stream System on the northern Bermuda Rise

Sohm Abyssal Plain: Evaluating Proximal Sediment Provenance

“…These latter observations could be interpreted as the result of long-term sediment dispersal trends toward the north and west quadrants. These patterns tend to support the oceanographic model of a westerly-directed return flow of the southern leg of the Gulf Stream Gyre above the Sohm Plain study area (Worthington, 1976;Laine, 1978).…”

“…This yellowish-brown layer accumulated between 40 and 165 cm from approximately 20,000 to 12,000 B.P., about the time of the most recent eustatic low sea level stand, followed by a rapid sea level rise. This was a cold period during and following major glaciation at the end of the Pleistocene (Laine, 1978). We also obtained two dates from Vema 22-231, on the plain proper, nearest the Lynch core: 31,700±1400 Figure 2), showing principal sediment types, color, and physical and biogenic structures, and the position and age (in years before present) of radiocarbon-dated samples; (5YR4/4 = moderate to reddish brown; 10YR4/2 = yellowish brown; 10YR6/2 = pale brown; dark vertical bars at right = position of x-radiographed core sections illustrated in Figure 15; see Table 1 for grain-size analyses of selected segments identified at left of log).…”

“…This large clockwise-rotating gyre is located east of Cape Hatteras, extends to about 40° W longitude, and is positioned over the Bermuda Rise and most of the Sohm Abyssal Plain. It is believed to influence the circulation pattern of the deeper waters, including those above the southern Sohm Abyssal Plain (Schmitz, 1977;Laine, 1978).…”

“…Interpretations of acoustically transparent layers are based on JOIDES deep-sea drilling results, bottom photography (Heezen and Hollister, 1971), nephelometry (Biscaye and Eittreim, 1977), and Daniel Jean Stanley and Harrison Sheng, Division of Sedimentology, Smithsonian Institution, Washington, D.C. 20560;Patrick T. Taylor, Earth Survey Applications Division, NASA Goddard Space Flight Center, Greenbelt, Md. 20771;and Robert Stuckenrath, Radiation Biology Laboratory, Smithsonian Institution, Washington, D.C. 20560. studies of water-mass motion (Laine, 1978). Various transport models, for the most part involving resuspension by bottom currents, have evolved from these investigations.…”

“…The discovery of a large clockwise-circulating gyre associated with the Gulf Stream System (Worthington, 1976) has led to a modification of the classic turbidite and nepheloid layer emplacement models for this area. According to Laine and Hollister (1981), flow associated with this gyre resuspends seafloor sediment and also entrains turbidity current flows periodically introduced into the Sohm Abyssal Plain from the Canadian Maritime Margin.…”