Stratigraphic Code PDF

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Lecture by Dr. Elvis Bello...

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Stratigraphic Code >The Stratigraphic Code is the law when it comes to naming and defining stratigraphic units >North American Commission on Stratigraphic Nomenclature, International Commission on Stratigraphy >Official Code Categories •there are twelve catevories of official stratigraphic units based on physical characteristics a time •the boundaries of one type do not necessarily coincide with those of another type •boundaries of any type of unit must be chosen so strata above and below can be distinguish by others •subdivisions of geologic units 1. lithostratigraphic 2. lithodemic 3. magnetostratigraphic 4. biostratigraphic 5. pedostratigraphic 6. allostratigraphic 7. chronostratigraphic 8. polarity chronostratigraphy 9. geochronologic 10. polarity chronologic 11. diachronic 12. geochronometric Formal and Informal Units >Formal units are those that are named in accordance with an established scheme of classification >Informal units are ordinary nouns, not protected by the stability of provided by proper formalization and ... Stratotype (type area) >A stratotype should include recognizable upper and lower contacts, should be highly representative of the unit's diagnostic characteristics, and should be complete (no fault, unconformity) > > Lithostratigraphic Units >Contacts between lithostratigraphic units can be sharp, gradational or interbedded, and are... > > >Lateral continuity • >Unconformities • lithostratigraphic units do not extend vertically across an unconformity

Lithodemic Units >Defined body of predominantly intrusive igneous and/or highly metamorphosed rock > > > >Type area •a type area description should... Magnetostratigraphic Units >Bodies of rock named on the basis of magnetic properties and stratigraphic position >Time does not play a part in the definition of these units...