1. Carbonate sediments are different Flashcards
1.1. Carbonate precipitation, productivity, accumulation rate and sea level variations 1.1. Carbonate productivity, accumulation rate and sea-level variations 1.2 Sediment supply and carbonate platform flooding Coe, 2003 1.3 Generalized comparison between siliciclastic and carbonate systems
How do siliclastic and carbonate deposition processes differ?
Siliclastic deposition is transported via bedload suspension and gravity flow.
Carbonates are produced in specific sedimentary basins called carbonate factories and are not transported. They form rigid structures, are not lithified, and exist in subdivided hydraulic platform environments.
What are the two ways carbonates precipitate?
Abiotic - Direct chemical precipitation involving no significant precipitation of biotic things, such as seawater. Processes is slow and needs pre-existing recreation points. NOT THE MAIN METHOD
Biotic - Organism-influenced precipitation via metabolism. Not controlled by organisms. Maininly microbial-induced. composed of skeletal fragments of heterotrophs and autotrophs.
Schlager 2003 defines what 3 types of carbonate factories?
Mud Mound: biotic, micritic. stairated structures made of mud. some with no light, others with limited light. High nutrients, low oxygen. found in basin slopes; deeper environments.
Tropical: tropical, topmost water with autotrophs. saturated in light, high in temperature. high oxygen but low nutrients.
Cool Water: Controlled precipitation, with heterotrophs. carbonate due to skeletons. no biotic or abiotic influences. no clay, no micrite, no mud, no marine cement. cleaned from matrix and protected from siliciclastic input.
Please describe Schlager 2003 defined carbonate factories in terms of production.
Draw a graphic representation
Mud mounds are mostly induced with abiotic factories. Sometimes depleted of skeletons, but it depends. Can be mud mounds with mud due to rising sea level.
Cool Water are controlled.
Tropical: varies, but mostly controlled.
How does depth impact Schlagers 2003 defined factories?
Mud mounds: occur in any depth’ deeper environment in hydrothermal systems.
Cool Water: localized at different depths at any current; swept.
Tropical: restricted to the first 100 meters and occurs in shallow environments because of sun sensitivity caused by Sea level change.
How can a mud mound structure demonstrate a basin environment? What does is composition say about temperature?
Draw a picture.
In warm sub-tropical, there are no corals, only algae.
In cold environments, you can find forams and mollusks.
Name a few things you would find in tropical and cool climate carbonate factories in varying temperatures
What are these two maps representing? Please explain in detail.
The top map shows the modern ocean.
The bottom shows oceans during the Cretaceous. There was limited C factories, so that is why the T factories is studied at that time.
Global warming at that time period increased sea level, increased in shallow water platforms, and increased T factory production
Carbonate production is influenced by biota. carbonate platforms are impacted by ocean currents. We study the current controls on this environment in order to understand the past.
Please draw a carbonate growth curve and explain it
mostly controlled by sea level change
Discuss the accumulation, dissolution, and accommodation space for carbonates
Warm Water carbonates can see up to 10 meters of accumulation in just 100 years. Cold water carbonates have a lower rate, except for mud mounds.
Ancient carbonates reflect closely cool-water carbonates.
Please explain this diagram
For T factories, increased rate of production follows increased rate of accumulation.
First to third order represents sea level and continental change.
First to third order and long term basin change have lower affect in cold water factors.
Remember a few things:
T factory will follow growth curve ( I think )
2 factors of climatic change in congruency with carbonate platforms are polar ice caps melting and faults that can raise production.
when materials are produced during accumulation, you have progradation of the platform, wheere dissolution is obserevd.
Between diffrent cycles you keep morphology of previous platform, and with each cycle you inherit diff platforms.
what is the main control of carbonate production?
Increase of surface area!
What are these pictures demonstrating?
Discuss Relative Sea level, Eustasim, and the 2 factors impacting flooded shallow platforms, and how those 2 factors impact productivity
Relative sea level change is local while eustasism is global. Be aware that you can local decrease in sea level, but a global increase.
Flooded shallow platforms are caused by the angle of platform (shelf or ramp) and relative sea level.
When the sea level reaches slope, high angle and low sea level can cause a low platform with low capacity to prograde.
Draw and compare siliciclastic and carbonate platforms throughout the system tract.
REMEMBER
For progradation at HST, angles of the sequence low at top, big at bottom
REMEMBER
beginning facies may show quick and slow sea level changes
Which system track does production rates greatly alter, and what can be seen depending on the rate?
FFST/LST
Loosely label this image
If the rate of accommodation at HST increases…
you can see an increase in thickness at the platform top. And if this is continued, you can get the same result for LST
Please describe this
