Graphic Correlation

Ron Martin
University of Delaware
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The objective of this exercise is to acquaint you with a simple graphic method that can be used to:
  1. determine changes in sediment accumulation rate,
  2. evaluate the completeness of different sections and environments, and
  3. infer the reliability of various types of datums when correlating sections.

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This exercise has been used in a junior level paleo course, junior level strat course, and grad level strat course.

Skills and concepts that students must have mastered

Basic stratigraphic concepts and principles, understanding of oxygen isotopes and paleomagnetic reversals.
NOTE: ANY type of datum may be used in graphic correlation, not just those used here.

How the activity is situated in the course

Varies, but must be situated somewhere later in the course after students have become familiar with lithocorrelation and biostratigraphy.


Content/concepts goals for this activity

By the end of the lab, students should understand how to:
►make a simple plot of two different sections
►infer what the plot tells one about changes in sediment accumulation rate and missing section (e.g., unconformities, condensed sections, and smaller-scale changes in accumulation rate) and the suitability of sections for correlation or paleoenvironmental/paleobiological interpretation (e.g., phylogeny, speciation)
►infer which datums in a particular section are most reliable for correlation
►understand how non-traditional datums can be used to provide greater temporal (time) resolution between standard biostratigraphic datums.

Higher order thinking skills goals for this activity

Critical evaluation of the continuity of stratigraphic sections and the reliability of various types of stratigraphic datums in relation to stratigraphic completeness and paleoenvironmental/paleobiological inference.

Other skills goals for this activity

Description of the activity/assignment

Students are sent an Excel file containing the depths of various types of datums from DSDP and ODP cores: biostratigraphic, oxygen isotope, and paleomagnetic datums.

They are then asked to plot datums from different cores (and settings) and evaluate the stratigraphic completeness of the cores based on the behavior of the datums.

After plotting the datums, they are asked a number of questions about stratigraphic completeness, reliability of datums, etc.

Determining whether students have met the goals

Assignments (plots, written answers) are collected and examined in relation to plots produced by the instructor. The exercise is based on actual research conducted by the instructor and is students, and published in peer-reviewed journals. However, students with different interpretations are not penalized if they adequately justify their interpretationsw.

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