Quantitative Stratigraphy, Splining and Geologic Time Scales - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 347

Morgan Creek White Creek Pontotoc

Ft. Ft. Ft.

600 800 700

0.5
1.0
2.0
3.0

0.5
1.0
2.0
3.0
4.0
5.0

M ARYVILLIA Z ONE

MARYVILLIA ZONE

SH AW 100

SHAW 100

4.0

500 600

C OOSE LLA Z ONE

5.0

5.5

5.5

400 500

6.0

6.0

SHAW 80

6.5

300 400

6.5

Fig. 9.31 Biostratigraphic correlation of three sections for the Riley Formation in central Texas
by means of three methods. Palmer's ( 1954 ) original biozones and Shaw's ( 1964 ) R.T.S. value
correlation lines were superimposed on CASC (Agterberg 1990 ) results. Error bars are projections
of single standard deviation on either side of probable positions for cumulative RASC distance
values equal to 2.0, 5.0 and 6.0, respectively. A cumulative RASC distance value is the sum of
interevent distances between events at stratigraphically higher levels. Uncertainty in positioning
the correlation lines increases rapidly in the stratigraphically downward direction. The example
shows that the three different methods used produce similar correlations (Source: Agterberg 1990 ,
Fig. 9.25)

9.4.3 Cretaceous Greenland-Norway Seaway
Microfossils Example

The final example of large-scale RASC/CASC applications is concerned with the
stratigraphic distribution of 1,755 foraminiferal and dinoflagellates microfossil
events in 31 wells from the Cretaceous seaway between Norway and Greenland
(after Gradstein et al. 1999 ). The emphasis in this example is on paleoceanographic
interpretation and use of RASC variance analysis, a technique developed in the late
1990s. Setting MNS 7 left 72 events that were augmented by 9 unique events.

Almost all events are last occurrences but several Last Common Occurrences

¼