SEDIMENTARY ARCHIVES
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SEDIMENTARY ARCHIVESClassification of Sedimentary Rocks
Carbonates
SEDIMENTARY ARCHIVESClassification of Sedimentary Rocks
CarbonatesOrigin of carbonate sediments
Much lime mud forms from the disintegration of calcareous algae (such as Halimeda and Penicillus).
When the calcareous algae die, their skeletons break down and disintegrate producing aragonite needle muds.
These lime muds lithify to form fine-grained limestone.
SEDIMENTARY ARCHIVES
SEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonates
Fossiliferous limestoneBiomicriteBiosparite
SEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonates
Oolitic limestoneOomicriteOosparite
SEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonates
DolostoneComposed of dolomite (CaMg(CO3)2)
The Dolomite “Problem”
Dolomite is believed to form when magnesium that has been concentrated in sea water replaces calcium carbonate in a previously deposited limestone.
Today, dolomite only forms in a few areas of the world where intense evaporation of seawater concentrates the magnesium.
Extensive areas of carbonate rocks of Precambrian, Paleozoic, and Mesozoic age have been altered to dolomite.
Dolomitization may be related to times of high sea level worldwide, under favorable climatic conditions.
SEDIMENTARY ARCHIVESClassification of Sedimentary Rocks
Clays, Mudrocks and Shales
Mudrocks are a very fine-grained Composed of clay and silt-sized particles
If the mudrock is fissile it is a -shale
Typically form in low energy environments
SEDIMENTARY ARCHIVESSea Level Changes
Eustatic Sea Level ChangeGlobal change in sea level position
Caused by: Glacial advance and retreatChange in spreading rates
Effect lowland areas
SEDIMENTARY ARCHIVESSea Level Changes
Sequence Stratigraphy
Epeiric seasSeas covered continentsProduced packages called sequencesLed to sequence stratigraphy
SEDIMENTARY ARCHIVESSea Level Changes Sequence Stratigraphy
Sequence Stratigraphy
A group of relatively conformable strata that represents a cycle of deposition and is bounded by unconformities or correlative conformities. Sequences are the fundamental unit of interpretation in sequence stratigraphy. Sequences comprise systems tracts.
SEDIMENTARY ARCHIVESSea Level Changes
SEDIMENTARY ARCHIVESSea Level Changes
Vail Curve
Sequence Stratigraphy
SEDIMENTARY ARCHIVESSea Level Changes
http://strata.geol.sc.edu/clastic-movie.html
SEDIMENTARY ARCHIVESSea Level Changes
Sequence Stratigraphy
THE FOSSIL RECORDPaleontology
Attempts to understand all aspects of the successionof plants and animals over time.
Based on study of fossils
Archaeopteryx
THE FOSSIL RECORDPaleontology
Fossil PreservationCover this aspect in laboratory
Fossilization fortuitous
Chances enhanced byHard partsRapid burial
Environments Oceans, lakes and streams
THE FOSSIL RECORDTaphonomy
What happens to an organism from time of death to preservation as a fossil
Soft parts usually lost