This page contains information about and related to magnetic stratigrapy, pedostratigraphy, allostratigraphy, and diachonous stratigraphy. Most of this information is from the North American Code of Stratigraphic Nomenclature.
Magnetic stratigraphy generalities
I.probably work well in Late Mesozoic & Cenozoic
II. names include
1. geographic term
2.type of magnetic zone
3. may add normal, reversed or mixed (where appropriate)
4. unit size: super unit >unit > subunit
basic paleomagnetic phenomena
1. polarity
2. field intensity
3. variations in non-pole magnetism (non-dipole component)
4. dipole-field-pole position (polar wandering)
The curie point
is temperature at which material loses any magnetism it has gained;
heating or cooling can pass through curie point.
Magnetopolarity
stratigraphy involves the body of rock with a specified
remnant-magnetic polarity. The prefix magneto- should always be used;
includes all aspects of remnant magnetic stratigraphy. The
magnetopolarity stratigraphy fundamental units are polarity zone or
magnetopolarity zone; polarity zone rocks may have one or more mixed
polarity - depends on definition. Magnetopolarity stratigraphy units
are sized: polarity superzone > polarity zone > polarity
subzone
Polarity-chronologic divisions of geologic time are based on magnetopolarity;
this is the same names as polarity-chronostratigraphic units. The
fundamental unit is polaritychron is not based on rock body. The size
of polarity-chronologic units is: polarity superchron > polarity
chron > polarity subchron.
Polarity
chronostratigraphic stratigraphy involves
the body of rock that contains primary magnetic-polarity from time of
origin. The size of units is polarity superchronozone > polarity
chronozone > polarity chronosubzone. An example of polarity
chronostratigraphic stratigraphy is time based on symmetrical
magnetic patterns in ocean floor. There are two purposes of polarity
chronostratigraphy 1. age correlation of rocks, 2. study earth's
polarity history.
Pedostratigraphphy involves traceable, buried soil horizons. It's requires
use requires criteria that soil scientists use to study modern soils.
Fundamental units are soils and geosols. The geosol name should
include a geographic term and geosol. Geosols are time transgressive;
fossils may give you idea of time range. Geosols are products of: 1.
surface alteration 2. physical properties make soil different from
parent material 3. soils form insitu can have parent of diverse
origin (till).
Retallack (1983)
studied Late Eocene-Late Oligocene paleosols of Badlands Natl. Pk.
found 87 paleosols in 143 m section, 10 paleosol types; found time to
form soil shortened from L. Eo. to L. Olig. because physical
conditions changed; noticed change in vegetation & minor tectonic
controlled sedimentation rate; because climate influences soil
genesis which affects vegetation he determined that: L. Eo. humid
forest, E. Olig. open woodland, L. Olig. semiarid-savanna with trees
by streams; uniformitarianism tells that different soils = different
forests
Allostratigraphy
involves the body of sedimentary rocks bounded by disconformities;
this type of work is useful in geomorphic studies. The fundamental
units same as lithostratigraphy with the prefix allo-.
Allostratigraphic units are not related to: age, genesis, geomorphic
surfaces, history or time; however these and other factors may
determine allostrat boundaries.
1. Allostratigraphic units may involve superimposed discontinuity
bounded units of the same lithology.
2. Allostratigraphic units may involve laterally adjacent
discontinuity bounded rocks.
3. Allostratigraphic units may involve geographically separated
discontinuity bounded units.
Diachronous
units are those of unequal amounts of time represented by other
units. For example transgression/regressions occur at different
places at different times producing a rock record in which one or
both boundaries are time transgressive. The ranking of these time
transgressive units is: episode > phase > span >
cline
Biostratigraphy