| One hundred drill core samples were from Deep Sea Drilling Project (DSDP) Sites 94, 98, and 540 were investigated for their palynological contents (pollen, spores, acritarchs, dinoflagellate cysts, and dispersed organic matter) to infer the paleoenvironmenal and paleoceanographic history of the Gulf of Mexico and the Bahamian Platform during the middle Eocene to middle Miocene interval. At Sites 94 and 540, abundant dinoflagellate cysts (chiefly Operculodinium centrocarpum, Lingulodinium machaerophorum, Impagidinium sp., Nematosphaeropsis sp., and Spiniferites spp.) were used as paleoenvironmental indicators. Two alternating palynofacies assemblages were identified from dispersed organic matter analysis: terrestrially influenced assemblage A and marine dominated assemblage B. The palynofacies and dinoflagellate cyst data indicated shallowing from oceanic to inner neritic environment from the Eocene to early Oligocene as global sea level dropped. Alternating neritic and oceanic depositional conditions prevailed during the late Oligocene and the Miocene. Palynomorphs recovered from these deep-water DSDP Sites were evaluated against 11 published studies of the Gulf coastal region and northern Colombia to infer the paleovegetation and/or depositional conditions on the adjacent landmasses. The drill core samples from Site 98 on the Atlantic side of the Bahamian Platform yielded a low diversity palynomorph assemblage. Terrestrially derived palynomorphs were extremely rare, and the dominance of amorphous organic matter indicated is consistent with deposition in marine environments. |
