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Sedimentary Facies & Sea Level Sedimentary Facies and Sea Level Changes.

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Presentation on theme: "Sedimentary Facies & Sea Level Sedimentary Facies and Sea Level Changes."— Presentation transcript:

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 sandstone facies shale facies

7 Two types of facies 1). Lithofacies: can be degree of difference Sedimentary Facies & Sea Level limestonesandstone 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 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 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” 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” 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 TransgressionRegression “deep” “beach” “land” “intermediate”

35

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?

39 1 meter rise

40 2 meter rise

41 6 meter rise

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


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