ABSTRACT

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

Core P6603-2, taken at a depth of 940 meters, at the location of 10°25N 64°38W, spans the late 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 one third to one quarter of that found in both the sediments above and below, whereas the thorium and protactinium contents remain constant.

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