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Stratigraphy & Correlation

Stratigraphy & Correlation. Stratigraphy & Correlation. Stratigraphy & Correlation. Stratigraphy & Correlation. Rock Record : • Three major ways of subdividing the geologic record:. Stratigraphy & Correlation. Stratigraphy & Correlation. Rock Units (lithology):

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Stratigraphy & Correlation

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  1. Stratigraphy & Correlation Stratigraphy & Correlation

  2. Stratigraphy & Correlation Stratigraphy & Correlation Rock Record: •Three major ways of subdividing the geologic record:

  3. Stratigraphy & Correlation Stratigraphy & Correlation Rock Units (lithology): • bodies of rock defined by their distinctive lithologic features

  4. Stratigraphy & Correlation Stratigraphy & Correlation Rock Units (lithology): • must be wide spread. = mapable.

  5. Stratigraphy & Correlation Stratigraphy & Correlation Divisions of Rock Units: Group Formation- fundamental unit Member Bed - informal unit

  6. http://www.answersincreation.org/images/grandcanyon_strat.gifhttp://www.answersincreation.org/images/grandcanyon_strat.gif

  7. http://www.answersincreation.org/images/grandcanyon_strat.gifhttp://www.answersincreation.org/images/grandcanyon_strat.gif

  8. Stratigraphy & Correlation Stratigraphy & Correlation Rock Unit Names are based on: 1) Geographic location (where first described) and 2) Rock type (lithology)

  9. Stratigraphy & Correlation Stratigraphy & Correlation • Rock Unit Names: for example • Blowing Rock Gneiss • Erwin Sandstone • Grand Father Mountain Formation • (mixed lithology)

  10. Stratigraphy & Correlation Stratigraphy & Correlation Characteristics of Rock Unit: • primarily an environmental indicator. • but environments change position through time.

  11. Stratigraphy & Correlation Stratigraphy & Correlation Characteristics of Rock Unit: therefore, boundaries of rock units do not correspond to time units !!!

  12. Stratigraphy & Correlation Stratigraphy & Correlation Characteristics of Rock Unit: • boundaries of rock units do not correspond to time!!

  13. Stratigraphy & Correlation Stratigraphy & Correlation 2. Time Units: (chronology) • intervals of time • independent of associated rocks (durations in millions of year).

  14. Stratigraphy & Correlation Stratigraphy & Correlation Division of Time Units: • Eon Era Period- fundamental unit Epoch Age

  15. Stratigraphy & Correlation Stratigraphy & Correlation Characteristics of Time Units: • not equal subdivisions (e.g. not equal divisions of say, 10 million yrs) • may include more than one rock type

  16. Stratigraphy & Correlation Stratigraphy & Correlation Characteristics of Time Units: time interval

  17. Stratigraphy & Correlation Stratigraphy & Correlation 3. Time-Rock Units: • All of the rocks deposited during a particular interval of time.

  18. Stratigraphy & Correlation Stratigraphy & Correlation Time-Rock Units: TimeTime-Rock Eon (Eonothem) Era (Erathem) PeriodSystem Epoch Series Age Stage

  19. Stratigraphy & Correlation Stratigraphy & Correlation All of the rocks deposited during the Cretaceous Period . . . Belong to the Time-Rock Unit of the Cretaceous System.

  20. Stratigraphy & Correlation Stratigraphy & Correlation Review:ways to divide the rock record Rock Units - lithology - can vary in age Time Units - unequal divisions of time, will have variable rock types Time-Rock Units - all of the rocks deposited during a given interval of time

  21. Stratigraphy & Correlation Stratigraphy & Correlation Correlation: • Establishment of an equivalence between two rock units.

  22. Stratigraphy & Correlation Stratigraphy & Correlation 1. Lithologic correlation: • determine whether two rock bodies are (or were) part of the same rock body.

  23. Stratigraphy & Correlation Stratigraphy & Correlation How? • physically trace the outcrop

  24. Stratigraphy & Correlation Stratigraphy & Correlation How? distinctive lithologic identity

  25. Stratigraphy & Correlation Stratigraphy & Correlation How? distinctive lithologic identity

  26. Stratigraphy & Correlation Stratigraphy & Correlation How? position in a stratigraphic sequence

  27. Stratigraphy & Correlation Stratigraphy & Correlation How? position in a stratigraphic sequence

  28. Stratigraphy & Correlation Stratigraphy & Correlation How? geophysical properties

  29. Stratigraphy & Correlation Stratigraphy & Correlation How? geophysical properties (e.g., radioactivity) Geiger counter    click, click    click, click http://library.thinkquest.org/C0126323/graphics/geiger_counter.jpg

  30. Stratigraphy & Correlation Stratigraphy & Correlation How? geophysical properties (e.g., radioactivity) click, click, click       click, click, click

  31. Stratigraphy & Correlation Stratigraphy & Correlation 2. Time correlation: • Process of determining whether two rock bodies were deposited at the same time.

  32. Stratigraphy & Correlation Stratigraphy & Correlation Time correlation: How? • Radiometric dating (e.g. 14C) • marker beds (e.g. volcanic ash bed) • paleomagnetic reversals

  33. Stratigraphy & Correlation Stratigraphy & Correlation 3. Biological Correlation: (Based on the Principle of Fossil Succession) • Rocks with the same fossil assemblages were deposited during the same interval in geologic time.

  34. Stratigraphy & Correlation

  35. Stratigraphy & Correlation

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