Stratigraphy Flashcards
What is Chronostratigraphy?
The characterization af rock strata by their relation (relative).
“Time-space axis’s”
Such as bio-, magneto-, chemo-, cyclo-statigraphy.
What is Geochronology?
The geological study of absolute time
What is the law of superposition?
Younger layers of rock are on top of older layers of rock.
Steno Steensen
What is the law of original horizontallity?
Layers of sedimentary rock are originally deposited flat.
What is the law of cross-cutting relationships?
Rocks layers A and B must be older than the intrusion C disturbing them.
What is an angular unconformity?
Vinkeldiskordans
The contact that separates a younger rock unit from older underlying rocks that are tilted or deformed layered rock.
An angle between the rock units
What is a disconformity?
A break in a sedimentary sequence which does not involve a difference of inclination between the strata on each side of the break
Hard to identify due to parallel units
What is an unconformity?
A surface of contact between two groups of unconformable strata.
Three types:
- Disconformity
- Angular disconformity
- Nonconformity
Det tidsrum hvorfra der mangler lag kaldes en hiatus.
What is Lithostratigraphy
The discription and systematic organisation of strata
What is biostratigraphy?
Correlation and relative ages based on fossils within the rock units
Biostratigraphic unit = Biozone
What is Cyclostratigraphy
based on cyclic alternation in strata
ex. Milankovitch cycles or monsoon cycles
What is Magnetostratigraphy?
Relative dating by using the frequent change in Earth’s magnetic polarity
for example seen in the oceanic anomalies (MOR)
What is Chemostratigraphy?
Chemical properties of rocks as a relative dating technic.
What is a nonconformity?
An erosional surface between nonsedimentary rock layer and a sedimentary rock layer.
Walters law
Law of correlation of facies
Conformable sedimentary units which lie in vertical succesion, represents the larterally sedimentary evironments migrating over one another thorugh time
Transgression => the stratigraphic order is reversed.
