(Table 2) Fission track ages of apatite and sphene from Paleogene sediments at DSDP Hole 81-555@en

Fission track ages of individual crystals of detrital apatite and sphene separated from early Eocene and Paleocene sandstones at Site 555 indicate the contribution of detritus from source rocks of at least three distinct age groups. A major group of Tertiary (56 ± 3 m.y.) apatite ages is compatible with either contemporaneous or near contemporaneous volcanism or rapid unroofing of high level intrusives like those identified previously on Rockall Island (Jones et al., 1972) and Greenland (Gleadow and Brooks, 1979). Cretaceous (100 ± 20 m.y.) apatite ages are consistent with known high level microgabbroic intrusives on Helen's Reef (Roberts et al., 1974). Such apatite ages could also be derived from basement rocks of very ancient terrains, especially around rifted continental margins where low level heating or uplift has affected the fission track ages of apatites (Gleadow, 1978). […]