Petrography and Paleoenvironmental Interpretation of Taloka and Dukamaje Formations, Southern Gadon Mata, Goronyo, Sokoto Basin-Nigeria

Petrographic study of the various rock units from Gadon Mata area of Goronyo in Sokoto Basin was carried out. Sedimentary structures were used for Paleoenvironmental Interpretation of Taloka and Dukamaje Formations from Sokoto Basin-Nigeria. The two formations which forms part of Rabah Sheet 11NE lies in the southeastern sector of the Iullemmeden Basin. The study area is bounded by latitudes 13018'38"N to 13021'58"N and longitudes 5047'47"E to 5050'35"E covering 30Km2. The mapping exercise was carried out using a topographic base map on the scale of 1:30,000. The area is made up of Maastrichtian sediments-Taloka and Dukamaje Formations. Taloka Formation is of deltaic/brackish water environment and is made up of white, grey, brown siltstones, friable sandstones, claystones and biogenic structures. It is of tidal flat depositional environment as confirmed by sedimentary structures like abundant bioturbation, rhythmic bedding and the wavy beddings. The Dukamaje Formation is of marginal marine environment comprising of shales, limestones and mudstones with vertebrate fragments. The abundance of mudcrack can be useful in the interpretation of paleoclimate as they are common in warmer climates. Similarly, while the calcite crystals exhibiting spherulitic texture observed in the thin section implies deposition in shallow agitated marine water of the Dukamaje Formation. Keywords: Petrographic, Sedimentary structures, Paleoenvironmental, Taloka, Dukamaje, Formation, Iullemmeden

Some aspects of fisheries ecology in Thomas dam, Kano Nigeria

The diversity, length-weight relationship and condition factor of fish species of Thomas Dam, Dambatta Kano were studied fortnightly between November, 2016 and February, 2017. Fish species were collected using line nets, cast nets, hooks and traps; weighted to the nearest gram and standard length measured to the nearest centimeter. A total 313 fishes comprising of 7 families and 11 species were identified. Family cichlidae was predominant(36.7%) represented by T. zilli (21.7%) and Oreochromis niloticus (15.0%). Family Claridae was the second highest in abundance with 24.7% represented by C. garipienus (8.9%), Clarias anguillaris (8.9%) and Heterobranchus sp. (6.7) while Protopteridae represented by Protopterus sp. was the least with 2.8%. Species diversity determined by Shannon Weiner index of diversity, Evenness index and Margalef’s index which revealed the highest value at site A of 1.45, 0.78 and 2.66 while site D had the least with 1.1, 0.64 and 1.72 respectively. Growth coefficient b of the length weight relationship ranged from 0.9 to 2.7 inHeterobranchussp. andClariasgariepinus. The b values of the all the fish species is less than the mean exponent b =3, indicating a negative allometric growth. Condition factor (K) for all fish species differed significantly (P<0.05) as the highest value was recorded in Mormyrus rume and Heterobranchus sp. with 1.9 each and the least were C. gariepinus and C. anguillaris, protopterus sp. and Labeo senegalensis each had 0.9 values respectively. The mean condition factor (K) by species was greater than 1, indicating that the fish species were not in good condition.KEY WORDS: Species diversity, Length-weight relationship, Condition factor, Allometric growth, Thomas Dam, Dambatta Kano State