Lithostratigraphic
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Lithostratigraphy is the subdivision of rock layers based on their lithology or rock type. Rock layers are divided into standardized units including supergroups, groups, formations, and members. Lithostratigraphic units are defined solely based on distinct rock compositions and types. Boundaries between lithostratigraphic units are placed at points of clear lithological changes, either where rock types sharply differ or where gradational changes allow arbitrary boundaries. The basic hierarchy of lithostratigraphic units ranked from highest to lowest includes supergroups, groups, and members.
Lithostratigraphic
- 2. LITHOSTRATIGRAPHY • Subdivision of rock successions into units on the basis of lithology or rock type • Lithostratigraphical standard units: • Supergroup • Group • Formation • Member • Bed
- 3. • Lithostratigraphic classification is the subdivision, classification, and organization of rock strata on the basis of their lithologic characters
- 4. • Lithostratigraphic unit : • based on the type of rock, • may consist of sedimentary, igneous-, or metamorphic rocks, or of an association of two or more of these • defined and distinguished solely by lithologic feature (primarily rock composition) suplemented by stratification/succession note : such features should normally be of such-a nature that they can be readily recognized in the field by a knowledgeable geologist
- 5. Boundaries of Lithostratigraphic Unit • Boundaries of lithostratigraphic unit, or boundaries between adjacent (either laterally or vertically) lithostratigraphic units: • are placed at points of lithologic change • will be placed at naturally occurring sharp or distinct contact between differing lithologies, • may be fixed arbitrarily within zones of lithologic gradation
- 6. Boundaries of Lithostratigraphic Unit • …placed at points of lithologic change • placed at naturally occurring sharp or distinct contact between differing lithologies Sandstone unit Claystone unit
- 7. Claystone unit Sandstone unit …fixed arbitrarily within zones of lithologic gradation ..this interval can be consider as another lithostratigraphic unit and known as … claystone - sandstone unit… …or boundary of claystone unit and sandstone unit “fixed arbitrarily” (red line) in the gradation boundary
- 8. Basic Hierarchy of Lithostratigraphic Unit • Basic hierarchy of ranks of formal lithostratigraphic units (from highest to lowest) are: supergroup, group, and member
- 15. 1,2,3, etc. : similar time gap A, B, C, etc. : lithostratigraphic unit boundary 10 m 0