Search results for: maastritchian

Authors: Njoku, Joy

Abstract:

The re-calibration of the Campanian to Maastritchian of some parts Anambra basin was carried outusing samples from two exploration wells (Amama-1 and Bara-1), Amama-1 (219M–1829M) and Bara-1 (317M-1594M). Palynological and Paleontological analyses werecarried out on 100 ditch cutting samples. The faunal and floral succession were of terrestrialand marine origin as described and logged. The well penetrated four stratigraphic units inAnambra Basin (the Nkporo, Mamu, Ajali and Nsukka) the wells yielded well preservedformanifera and palynormorphs. The well yielded 53 species of foram and 69 species ofpalynomorphs, with 12 genera Bara-1 (25 Species of foram and 101 species of palynormorphs). Amama-1permitted the recognition of 21 genera with 31 formainiferal assemblage zones, 32 pollen and 37 sporesassemblage zones, and dinoflagellate cyst, biozonation, ranging from late Campanian – earlyPaleocene. Bara-1 yielded (60 pollen, 41 spore assemblage zone and 18 dinoflagellate cyst).The zones, in stratigraphically ascending order for the foraminifera and palynomorphs are asfollows. AmamaBiozone A-Globotruncanellahavanensis zone: Late Campanian –Maastrichtian (695 – 1829m) Biozone B-Morozovellavelascoensis zone: Early Paleocene(165–695m) Bara-1 Biozone A-Globotruncanellahavanensis zone: Late Campanian(1512m) Biozone B-Bolivinaafra, B. explicate zone: Maastrichtian (634–1204m) BiozoneC- Indeterminate (305 – 634m) Palynological Amama-1 A.Ctenolophoniditescostatus zone:Early Maastrichtian (1829m) B-Retidiporitesminiporatus Zone: Late Maastrichtian (1274m)Constructipollenitesineffectus Zone: Early Paleocene(695m) Bara-1 Droseriditessenonicus Zone: Late Campanian (994– 1600m) B. Ctenolophoniditescostatus Zone: EarlyMaastrichtian (713–994m) C. Retidiporitesminiporatus Zone: Late Maastrichtian (305 –713m) The paleo – environment of deposition were determined to range from non-marine toouter netritic. A detailed categorization of the palynormorphs into terrestrially derivedpalynormorphs and marine derived palynormorphs based on the distribution of three broadvegetation types; mangrove, fresh water swamps and hinther land communities were used toevaluate sea level fluctuations with respect to sediments deposited in the basins and linkedwith a particular depositional system tract. Amama-1 recorded 4 maximum flooding surface(MFS) at depth 165-1829, dated b/w 61ma-76ma and three sequence boundary(SB) at depth1048m-1533m and 1581 dated b/w 634m-1387m, dated 69.5ma-82ma and four sequenceboundary(SB) at 552m-876m, dated 68ma-77.5ma respectively. The application ofecostratigraphic description is characterised by the prominent expansion of the hinterlandcomponent consisting of the Mangrove to Lowland Rainforest and Afromontane – Savannah vegetation.

Keywords: formanifera, palynomorphs. campanian, maastritchian, ecostratigraphic anambra

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Authors: Adetunji Olusegun Aderigibigbe

Abstract:

Shales, especially black shales, are of great geological significance, in the study of heavy/trace metal contamination. This is due to their abundance in occurrence and high concentration of heavy metals embedded which are released during their weathering. Heavy metals constitute one of the most dangerous pollution known to human because they are toxic (i.e., carcinogenic), non-biodegradable and can enter the global eco-biological circle. In the past, heavy metal contamination in aquatic environment and agricultural top soil has been attributed to industrial wastes, mining extractions and pollution from traffic vehicles; only a few studies have focused on weathering of shale as possible source of heavy metal contamination. Based on the above background, this study attempts to establish weathering of shale as possible source of trace/heavy metal contaminations. This was done by carefully selecting fresh and their corresponding weathered shale samples from selected localities in Bida and Anambra Basins. The samples were analysed in Activation Laboratories Ltd; Ontario, Canada for trace/heavy metal. It was observed that some major and trace metals were released during weathering, i.e., some were depleted and some enriched. By this contamination of water zones and agricultural top soils are not only traceable to biogenic processes but geogenic inputs (weathering of shale) as well.

Keywords: contamination, fresh samples, heavy metals, pollution, shales, trace metals, weathered samples

Procedia PDF Downloads 116