Ichnology of the late Pleistocene Port Morant Formation of southeastern Jamaica

Late Pleistocene lagoonal siliciclastic strata (approximately 10 m thick) of the Port Morant Formation, exposed on the southeastern side and east of Port Morant Harbour, southeast coastal Jamaica, contain a relatively abundant and moderately diverse ichnofauna that is described herein in detail. The sequence contains soft-sediment ichnotaxa (Ophiomorpha nodosa Lundgren, 1891; Palaeophycus tubularis Hall, 1847; Thalassinoides paradoxicus (Woodward, 1830)) and those formed as a consequence of bioerosion (Caulostrepsis cf. contorta Bromley and D'Alessandro, 1983, C. cretacea (Voight, 1971), C. taeniola Clarke, 1908; Clionoides thomasi Fenton and Fenton, 1932; Entobia ovula Bromley and D'Alessandro, 1984, Entobia isp. or ispp; Gastrochaenolites cf. cluniformis Kelly and Bromley, 1984, O. simplex Bromley, 1981). Only P. tubularis, O. paraboloides and O. simplex have previously been described from the Jamaican rock record; the remainder are therefore formally documented for the first time. The sequence can be subdivided into three units. In ascending stratigraphic order, unit 1 comprises an erosionally-based boulder conglomerate, and units 2 and 3 of clay-rich, calcareous, fine-to course-grained sandstones. Small scleractinian coral patch reefs and isolated heads occur at the base of unit 2, and laterally discontinuous (southwards) pebble conglomerates are present at the base of unit 3. Soft-sediment ichnotaxa occur in units 2 and 3, whereas bioerosional ichnotaxa occur in association with unit 1, the patch reefs of unit 2, and two abundantly fossiliferous horizons near the top of unit 3.