NOTES ON APPLIED GEOLOGY

1. NOTES ONAPPLIED GEOLOGY

2. BEDDING • Bed : Sedimentation unit greater than 1cm. • Lamina: Sedimentation unit smaller than 1cm. • Interbedded: between two things

3. STRATIGRAPHY • Stratigraphic unit A naturally occuring body of rock or rock material which is distinguished from adjoining rock on the basis of some stated property or properties. • Lithostratigraphic unit. • Biostratigraphic unit. • Chronostratigraphic unit. • Geochronologic unit.

4. Lithostratigraphic Unit (( is a stratum or body of strata, generally layered which conforms to the law of superposition and is distinguished and delimited on the basis of lithic characteristics and stratigraphic position.))

5. Nature of Lithostratigraphic Units • Type section and locality. • Independence from inferred Geologic history. • Independence from time concepts.

6. Are placed at positions of lithic change. Boundaries in lateral lithologic change. Correspondence with generic units. Boundaries

7. Lithostratigraphic boundaries

8. Rank of Lithologic Units

9. Formation It is the fundamental unit in lithostratigraphic classification. • Content: A formation should posses some degree of internal homogeneity or distinct features. • One lithic type. • Repetitions of two or more lithic types. • Extrem lithic heterogenity. • Lithic characteristics. • Mappability and thickness.

10. Lithostratigraphic Nomenclature • Compound character: Geographic +Lithic term+ Rank. Geographic + Rank. Geographic + Lithic + Rank. • Use of Simple lithic terms. • Misuse of well known name.

11. Clay Minerals A term reserved for those constituents of a clay which give it its plastic properties. They are hydrous aluminosilicates. • Generally occur as minute, platy, rarely fibrous crystals. • Some contain loosely bonded cations which can be easily exchanged. • Ability to loose or take up water. • Produced by the degradation of other silicates. • Both two and three layered types are known.

12. The sheets of clay minerals

13. Clay minerals (continue) • Layers of Al - O/OH are called “gibbsite”. • Layers of Mg – O/OH are called “brucite”. • The stacking arrangement of the sheets determine the clay mineral type, as does the replacement of the Si and Al inons.

14. I. Kandit Group • Members have two – layered structure consisting of a silica tetrahedral sheet linked to an alumina octahedral sheet by common O/OH ions. • No replacement occur for Si or Al. • The structure formula is (OH)4Al2Si2O5. e.g Kaolinite

15. II. Smectite Group • Members have a three – layered structure. • Have ability for Al and Si exchange. • Have ability for absorbing water. • e.g Montmorillonite (Mg,Ca)O.Al2O3.5SiO2.nH2O

16. Three – layered structure.

17. Pre-Burial changes: Burrowing organisms effect. Adjustment to eH and pH. Adjustment to major cations. Development of Authigenic menerals. Early-Burial changes Continuation of 2 & 3. Oxidation of carbonaceous material. Continuation of compaction. Probable initiation of concretions. Start of primary cementation. Some conversation of aragonite to calcite, and development of dolomite. Diagensis

18. Diagensis(continue) • Late – Burial Changes: • Cease of eH and pH adjustments. • Completion of compaction. • Authigenic mica & chlorite. • Completion of concretions development and cementation. • Replacement of aragonite by calcite; dolomitization.

19. Sedimentary Rock Types Rocks formed from material derived from pre-existing rocks by processes of denudation, together with material of organic origin.

20. Lithological Description • Type of formation (Limestone, sandstone, shale…). • Colour. • Texture. • Cementing material. • Hardness. • Porosity. • Minor components (accessories). • Staining and fluorescence (oil shows).

21. 3. Texture • Sediments with visible graine size: • Size, • Sorting, • Roundness, • Sphericity. • Sediments with crystalline appearance. estimate crystallinity: • Microcrystalline • Cryptocrystalline • Succrose • Sediments without recognizable size at ordinary microscope: Descripe the morphology of the cutting.

22. Depositional texture not recognized. Crystalline carbonate. Dunham Classification

23. Depositional texture recognized • Depositional texture recoginized. • Original components bound together • Boundstone.

24. Mud supported

25. Grain supported

26. Dunham Classification

27. Dunham Classification

28. 5. Hardness Hardness is a reflection of degree of cementation. • Soft or friable • Moderately hard; fairly cemented. • Hard; moderately cemented. • Very hard; well cemented.

29. 6. Porosity • Porosity could be estimated from hardness and cementation. • Archi classification • matrix porosity • Compact, dense, hard • Chaiky, earthy, soft. • Sugary, loose, poorly cemented. • Visible porosity • No visible pores w/ 10x • Visible w/ 10x • Visible w/ eye. • Larger than 2 mm

30. 7. Minor constituents

31. Oil Shows DescriptionA. In Normal Light • Percentage • No visible stain • Poor stain • Fair stain • Good stain 40%

32. Distribution Uniform Scattered Spoty Streaked Shade V. Light Light Medium Dark Very dark Hue Green Yellow Brown Black Oil Shows DescriptionA. In Normal Light

33. Oil Shows DescriptionB. Under UV Light • Intensity • No florescence • Faint • Dull • bright

34. Distribution Uniform Scattered Spoty Streaked Shade V. Light Light Medium Dark Very dark Hue Blue white Yellow, Orange Gold Brown Oil Shows DescriptionB. Under UV light

35. Stream cut: Immediate Fast Slow Discoloration Very slow Slow Fast Crush cut Poor Fair Good Allow the solvent to evaporate, describe the fluorescence of the ring as well as the color of the ring in the day light. C. Cuts & D. Residual ring

36. Thanks