PALYNOZONATION, CHRONOSTRATIGRAPHY AND PALEOENVIRONMENT OF DEPOSITION OF THE ALBIAN TO PLIOCENE SEDIMENTS OF NZAM-1 WELL, ANAMBRA BASIN, SOUTHEASTERN NIGERIA

Palynology was used as tool to investigate the stratigraphic sequence of Anambra Basin based on identified discrepancies in formation ages. The study was predicated on establishing palynological zones, chronostratigraphy and paleoenvironment of deposition of sediments using Nzam-1 well. The analyses involved lithological description and palynological studies using 556 and 132 samples respectively. Lithological textural characteristics were determined while palynological analyses involved decarbonisation, maceration, sieving, oxidation, heavy liquid separation, mounting of macerals on glass slides and observation of prepared slides under the microscope.

Lithostratigraphy of the analyzed well contains various lithoafacies such as shale, sandstone, siltstone, their heterolith and intercalated gypsum. Ten palynological zones were established including Forma PO 304 Lawal zone 1, dated Albian-Lower Cenomanian; Cretacaeiporites spp. acme zone 2, dated Upper Cenomanian-Turonian; Zlivisporites blanensis zone 3, dated Coniacian-?Santonian; Milfordia spp. Acme zone 4, dated Campanian; Foveotriletes margaritae zone 5, dated Lower Maastrichtian; Longapertites margaritae zone 6, dated Middle Maastrichtian; Spinizonocolpites bacculatus zone 7, dated Upper Maastrichtian; Mauritiidites crassibaculatus zone 8, dated Lower Paleocene; Monoporites annulatus zone 9, dated Middle Eocene; Echitirolporites spinosus zone 10, dated Upper Miocene-Pliocene age. In the Nzam-1, Ajali Sandstone was not encountered.. Sequnce stratigraphy analysis indicated six sequences of events characterized by 5 sequence boundaries (SB) and 8 maximum flooding surfaces (MFS). Paleoenvironment of deposition vary tremendously from fluviatile through marginal marine to open marine systems. The established palynological zones would assist in solving stratigraphic problems; optimize hydrocarbon exploration in Anambra Basin and other Cretaceous sedimentary basins in Nigeria.