Controls on Sedimentation
I Rock Type
II Unit Thickness
III Rock Packages (Facies Patterns)
IV Tectonics and Sedimentation
V Sea Level Cycles
VI Sequence Stratigraphy
VII Geochemical Cycles
VIII Carbonate Platform Models
Geology 3550
Sedimentation &
Stratigraphy
Controls on Sedimentation
I Rock Type
•Composition
Source - Acid, Basic, Sed
Climate - Weathering
Carb vs Noncarb
•Texture
(Source)
Transport - Mechanism, Time/Distance
Energy at Depocenter - Sea level, Topography
Controls on Sedimentation
II Unit Thickness
•Sedimentation Rate
Environmental Control (e.g. Schindel)
Clastics - Proximity to Source & Sediment Supply
Carbonates - Biogenic Production Rate
•Accommodation Space
Tectonics/Subsidence
Faulting + Passive Margin Downwarping +
Intracratonic Basin Subsidence +
Sediment Loading (e.g. Foreland Basin) +
Sea Level Rise + or Fall Magnitude
Rate
•Time
Controls on Sedimentation
III Rock Packages (Facies Patterns)
Facies Migration (Walther's Law)
•Eustatic Changes
•Vertical Tectonics
•Sedimentation
Progradation
“Give Up” (Carbonates)
Impoundment (Clastics)
Controls on Sedimentation
IV Tectonics and Sedimentation
•Basic Mechanism
•Effects
Local/Basin
Uplift/Erosion
Provide Source
Margin Subsidence - Cooling Plate
Local Climate - Latitude, Elevation
Global
Tectono-eustatic Changes - Ridge Volume
Ice/Climate - Volcanism and CO2
•Tectonic Setting of Sedimentary Environments
IV Tectonics and Sedimentation (cont.)
Tectonic Setting of Sedimentary Environments
•Intraplate
Intracratonic Basins**
Ocean Basins
Continental Rises and Terraces - Trailing Edge**
•Convergent Settings
Trenches
Forearc Basins*
Backarc Basins
Foreland Basins*
Piggyback Basins
•Divergent Settings
Terrestrial Rift Valleys**
Proto-Oceanic Rift Troughs
•Transform Settings
Transtensional Basins*
Transpressional Basins
Transrotational Basins*
* Good preservation potential
Controls on Sedimentation
V Sea Level Cycles
•Within Basin
Autocyclic/Intrinsic (e.g. uplift, downwarping)
Allocyclic/Extrinsic (e.g. eustasy)
•Global
Lower Order (Long Term) - Tectonics
Fischer Cycles
Sloss/Vail Curves - Cycles, Supercycles, Etc.
Higher Order (Short Term) - Milankovitch Orbital Mechanism
Sequences
Parasequences
Sub-Milankovitch Cyclicity
Orders of Cyclicity
Order
1
Fischer Cycle
(Icehouse/
Greenhouse)
2
Supercycle,
Cratonal Sequence
3
Cycle,
Grand Cycle,
DEPOSITIONAL
SEQUENCE
(ABC,ABC,ABC)
Period
Thickness
Mechanism
50+ Ma
~10,000 m
(Erathem Scale)
Tectonics
27 - 40 Ma
~1,000 m
(System Scale)
Tectonics
0.5 - 5 Ma
~100 m
(Formation Scale)
Tectonics
Order
4
Cyclothem,
PARASEQUENCE
5
Cyclothem,
Rhythmite,
PARASEQUENCE
6
Rhythmite,
Minor Cycle
>6
Rhythmite
(AB,AB,AB)
Period
0.1 - 0.5 Ma
(100 - 500 ky)
Thickness
Mechanism
~10 - 100 m
(Member Scale)
Milankovitch Ellipticity /
Eccentricity
~1 - 10 m
Milankovitch Obliquity /
Precession
0.02 - 0.1 Ma
(20 - 100 ky)
~0.01 - 1 m
Sub-Milankovitch
Climate Trends
~10-4 - 10-3 m
Storms, Annual
Climate Change
0.001 - 0.01 Ma
(1 - 10 ky)
10-6 - 10-4 Ma
(.001 - 1 ky)
Controls on Sedimentation
VI Sequence Stratigraphy
Sequence - unconformity-bounded package
(Allostratigraphic Unit)
Sequence Architecture
•Bounding surfaces
Maximum Progradation Surface
Transgressive Surface
Maximum Flooding Surface
Sequence Boundary (or Boundary Zone)
•Systems Tracts
Lowstand Systems Tract
Transgressive Systems Tract
Highstand Systems Tract
Controls on Sedimentation
VI Sequence Stratigraphy (cont.)
Sequence Architecture
•Systems Tracts
Lowstand Systems Tract
- Clastics prograde
- Carbonates karsted
- LST often absent in carbonate systems
Transgressive Systems Tract
- Clastics impounded
- Carbonate factory shuts down
- Hardgrounds
- Fossil lags
Highstand Systems Tract
- Clastics still impounded
- Carbonate factory starts up and may prograde
(= highstand shedding)
Controls on Sedimentation
VII Geochemical Cycles
Secular Variation
•CO2 Sinks
(evolution of
calcareous
plankton)
Planktonic Forams
(Jur. - Rec.)
•Ca/Mg
•Rock Volumes
Planktonic Coccoliths
(Trias. - Rec