facies shift off-shore.ppt
- 1. Sedimentary Facies & Sea Level Sedimentary Facies and Sea Level Changes
- 2. Sedimentary Facies: • general appearance or aspects of a rock (composition & texture). Sedimentary Facies & Sea Level
- 3. Sedimentary Facies: • original environment of deposition can be determined. • used to describe vertical and lateral variations in strata. Sedimentary Facies & Sea Level
- 4. Sedimentary Facies: • facies transform laterally by gradual changes in their properties into different, adjacent facies. Sedimentary Facies & Sea Level
- 5. Two types of facies 1). Lithofacies: distinguishing characteristics are . . . lithologic Sedimentary Facies & Sea Level
- 6. Sedimentary Facies & Sea Level sandstone facies shale facies
- 7. Two types of facies 1). Lithofacies: can be degree of difference Sedimentary Facies & Sea Level limestone sandstone vs. vs. fine grained limestone coarse, well sorted sandstone
- 8. Two types of facies 2). Biofacies: differences in biological (fossil) composition. Sedimentary Facies & Sea Level
- 9. Two types of facies 2). Biofacies: • can have different adjacent biofacies in the same lithology • can be sensitive to small environmental differences Sedimentary Facies & Sea Level
- 10. Sedimentary Facies & Sea Level Foraminifera facies Mississippi Delta
- 11. Sedimentary Facies & Sea Level Changes in sea level
- 12. Transgression: • Advance of sea over the land Regression: • Retreat of the sea from the land Sedimentary Facies & Sea Level
- 13. Idealized gradation: • Near shore = coarse sediment - to - • Off shore = fine sediment - yielding to - • Shelf carbonate deposition Sedimentary Facies & Sea Level
- 14. Idealized gradation: Sedimentary Facies & Sea Level near shore off shore continent
- 15. No sea level change: Sedimentary Facies & Sea Level near shore off shore continent http://www.uh.edu/~jbutler/physical/transreg.gif sediment through time
- 16. Sea level at Time A: Sedimentary Facies & Sea Level “the beach” Sea level change: cross section
- 17. Sea level at Time B: Sedimentary Facies & Sea Level “the beach”
- 18. Sedimentary Facies & Sea Level Transgression • facies shift on-shore • resulting rock unit (sandstone) varies in age laterally
- 19. Shift from Time A to Time B: Sedimentary Facies & Sea Level “the beach” “the beach” Transgression • facies shift on-shore • resulting rock unit (sandstone) varies in age laterally
- 20. Time A: on the beach (sandstone) Sedimentary Facies & Sea Level Stand in one spot during a transgression:
- 21. Time B: underwater (finer sediment) Sedimentary Facies & Sea Level Stand in one spot during a transgression:
- 22. Regression: • facies shift off-shore Sedimentary Facies & Sea Level
- 23. Regression: • facies shift off-shore Sedimentary Facies & Sea Level “the beach” “the beach” Time A Time B
- 24. Regression: • in one place, facies become more “onshore” (= coarser) up section Sedimentary Facies & Sea Level Ls Slt Ss fine course
- 25. • In a vertical column, facies become progressively more "on shore" (coarser) up section. Sedimentary Facies & Sea Level Regression Conglomerate Sandstone Siltstone Limestone erosion
- 26. • In a vertical column, facies become progressively more "on shore" (coarser) up section. Sedimentary Facies & Sea Level Regression Conglomerate Sandstone Siltstone Limestone erosion “deep” “beach” “land”
- 27. • In a vertical column, facies become progressively more ”off shore" (finer) up section. Sedimentary Facies & Sea Level Transgression Limestone Siltstone Sandstone Conglomerate erosion
- 28. • In a vertical column, facies become progressively more ”off shore" (finer) up section. Sedimentary Facies & Sea Level Transgression Limestone Siltstone Sandstone Conglomerate erosion “deep” “beach” “land”
- 29. • A vertical sequence represents facies that were once laterally continuous Sedimentary Facies & Sea Level Walther’s Law Limestone Siltstone Sandstone vertical sequence
- 30. • A vertical sequence represents facies that were once laterally continuous Sedimentary Facies & Sea Level Walther’s Law Limestone Siltstone Sandstone vertical sequence Lateral Distribution
- 31. Ls Sh Ss • A vertical sequence represents facies that were once laterally continuous Walther’s Law
- 32. Ls Sh Ss “deep” “beach” • A vertical sequence represents facies that were once laterally continuous Walther’s Law
- 33. • The relative sequence is more important than absolute completeness. Sedimentary Facies & Sea Level Walther’s Law Limestone Sandstone vertical sequence-1 Siltstone vertical sequence-2 unconformity
- 34. • The relative sequence is more important than absolute completeness. Sedimentary Facies & Sea Level Walther’s Law Limestone Sandstone vertical sequence-1 Siltstone vertical sequence-2 unconformity Transgression Regression “deep” “beach” “land” “intermediate”
- 36. • Tectonic subsidence (sinking) • Rise in sea level • Erosion of shore line Sedimentary Facies & Sea Level What cause a Transgression?
- 37. • Tectonic uplift • Drop in sea level • Over supply of sediment Sedimentary Facies & Sea Level What cause a Regression?
- 38. 1. Continental Glaciation more ice = lower sea level (max. 200 meter change) Sedimentary Facies & Sea Level Eustatic sea level change (world wide) - causes?
- 42. 30 meter rise
- 43. 100 meter rise link to: USGS
- 44. 2. Plate Tectonics fast spreading rate = high sea level slow = low sea level (affects the shape of ocean basins) Sedimentary Facies & Sea Level Eustatic sea level change (world wide) - causes?
- 45. • transgression in one place while regression in another • local mountain uplift or crustal subsidence • very rapid influx of sediment or erosion. Sedimentary Facies & Sea Level Local sea level change