Lithostratigraphy Flashcards
can be considered as the relationship
between rocks and time
Stratigraphy
is concerned with the observation, description and
interpretation of direct and tangible evidence in
rocks to determine the history of the earth.
Stratigrapher
forms the basis for making geological maps and by
correlating lithostratigraphic units, it is possible to
reconstruct the changing paleogeography of an
area through time
Lithostratigraphy
A body of rock or strata that can be distinguished and defined by its lithological characteristics and its stratigraphic position relative to other bodies
Lithostratigraphic Units
- are geological time units
- expressed in a time frame
Geochronology
- Stratigraphic material units
- a unit of rock
Chronostratigraphy
Geochronological Units (5)
Eon Era Period Epoch Age
Chronostratigraphic Unit (5)
Eonothem Erathem System Series Stage
these are the longest periods of time within the
history of the Earth
Eon
these are the three time divisions of the Phanerozoic
Era
The basic unit of geologic time and commonly used term when referring to Earth’s history
Period
is used for the rocks deposited in a particular period.
System
are the main divisions of periods
Epoch
the chronostratigraphic equivalent of Epoch
Series
The smallest commonly used divisions of geological time
Age
-where the age of the rock can be directly or
indirectly determined, a chronostratigraphic unit
can be defined
Chronostratigraphic Unit
is principally used for determining the age of formation of igneous rocks, including volcanic units that occur within sedimentary strata
Radiometric Dating
a body of rock or succession of rock layers that are mainly defined and characterized by fossils content
Biostratigraphic Unit
a body of rock which exhibits magnetic properties that are different to adjacent bodies of rock in the stratigraphic succession
Magnetostratigraphic Unit
have upper and lower boundaries that are
each isochronous surfaces, that is, a surface
that formed at one time
Chronostratigraphic Unit
Are short periods of time that are sometimes determined from palaeomagnetic information but these units don’t have widespread usage outside of
magnetostratigraphy which can be applied
to Quaternary
Chrons
Provided the rocks are the left way below the
beds higher in the stratigraphic sequence of
deposit would be younger than below but,
extra careful must be exercised when dealing
with stratigraphic relations along reefs etc
Superposition
- is equivalent to the formation unit of Lithostratigraphic units
- basic unit of lithodemic unit
- non stratiform bodies of rock
Lithodeme
An association of lithodemes that share the same lithological properties
Suite
is used as the equivalent to a group for volcanic or
tectonically deformed rocks.
Complex
is the original or subsequently designated type section of a named layered stratigraphic unit or of a stratigraphic boundary representing a specific interval or point in a specific sequence of rock strata
Stratotype
is the location where the lithological characteristics are clear and if possible, where the lower and upper
boundaries of the formation can be seen
Type Section
is a break in sedimentation and where there is erosion of the underlying strata
Unconformity
break in deposition and erosion within a stratigraphic succession
Disconformity
Any unit that has boundaries that cut across other strata must be younger than the rocks it cuts
Cross-cutting Relationship
The direction through the layers towards younger rocks. The direction of younging can be determined by small-scale features that indicate the way-up of
the beds
Way Up Indicator
a formal assemblage of related or superposed groups or of groups and formations
Supergroup
consists of assemblages of formations, but need to be composed entirely of named formations
Group
are grouped to form higher rank lithostratigraphic units are divided to form lower rank units
Formation
the formal stratigraphic unit next in rank below a formation and always part of some formation.
Member
a geographically restricted member that terminates on all sides within a formation
Lens
a wedge shaped member that extends beyond the main boundary of a formation or that wedges or pinches out within another formation
Tongue
distinctive subdivisions of a member, the smallest formal lithostratigraphic unit of sedimentary rock.
Beds
the smallest formal lithostratigrphic unit of volcanic rock
Flow
- formation as evidence of changing of environments
- Formation as being either diachronous or synchronous unit
Depositional Environments
Considering Formation in a Temporal Framework
Correlation
