More than 650 DSDP samples were studied using Masran & Pocock's 1981 classification of particulate organic matter to define a number of particulate organic matter assemblages; these assemblages are characterized both by their source material and the mode of preservation. Both marine and terrestrial sources can be identified. The distribution of these assemblages shows that: (1) the eastern deep North Atlantic, Gulf of Mexico, Caribbean, and Demerara Rise are characterized by a high proportion of marine derived matter; (2) western North Atlantic sites received a high input of terrestrial organic matter; (3) marine-derived material is dominant in Cenomanian sediments of all areas; (4) highly degraded gray amorphous matter, indicating low oxygen conditions, occurs throug out the deep North Atlantic Ocean; (5) circular bodies, occurring in all areas, are interpreted as remains of seaweed spores; and (6) the distribution of various types of organic matter assemblages agrees with the sedimentology studies given in the various reports of the Deep Sea Drilling Project.

The cyclicity reported by sedimentologists is also recognized in the contained organic matter. Its origin must be explained in terms of preservational mode of the organic matter, its original source (marine or terrestrial), and mode of original and final sedimentary deposition.

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