The geochemistry of uranium and thorium isotopes and of protactinium was investigated in cores from the Cariaco Trench. Though the sediments could not be dated, they showed some features characteristic to anoxic basins. Uranium is a very valuable marker for geologic events.

Core P6603-2, taken at a depth of 940 m, at 10°25^primeN long., 64°38^primeW lat., spans the upper Pleistocene. At 356 cm there is a sharp break between the laminated sediments above and a homogeneous clay below. The uranium content shows a significant change at the 354-359 cm interval. The uranium present in this narrow band is only a third to a quarter of that found in the sediments above and below, whereas the thorium and protactinium contents remain constant.

End_of_Article - Last_Page 2044------------