Automated Stratigraphic Correlation

This book provides an introduction to recent developments in automated stratigraphic correlation of fossil data, using computer programs for ranking and scaling of stratigraphic events. Mainframes or microcomputers can be used to aid the stratigrapher during data inventory for a region or time period, for construction of a biozonation based on stratigraphic events, (such as the latest appearance datum of a fossil species), and for automated correlation.

The book is intended for advanced geology students, research workers and teachers with a background in stratigraphy and an interest in using computer-based techniques for problem-solving.

Contenu

1. PROBABILISTIC METHOD FOR AUTOMATED STRATIGRAPHIC CORRELATION. Introduction. IGCP Project 148. Quantitative biostratigraphy. Quantitative chronostratigraphy. Quantitative lithostratigraphy. Recent developments in stratigraphy. 2. PRINCIPLES OF QUANTITATIVE STRATIGRAPHY. Introduction. Zones in biostratigraphy. Quantitative versus qualitative stratigraphy. Local versus regional ranges of taxa. Estimation of the highest and lowest occurrences of taxa. The frequency distributions of highest and lowest occurrences of taxa. 3. APPLICATIONS OF MATHEMATICAL STATISTICS AND COMPUTER SCIENCE TO ZONATION, CORRELATION AND AGE INTERPOLATION. Introduction. Binomial test for randomness. Binomial distribution model for microfossil abundance data. Multiple pairwise comparison. Applications of graph theory. Use of cubic smoothing splines for removing ``noise'' from microfossil abundance data. Biostratigraphic correlation between Tojeira 1 and 2 sections in central Portugal using E. mosquensis abundance data. Multivariate methods. Research on time-scales. Computer simulation experiments on estimation of the age of chronostratigraphic boundaries. Smoothing of time-scales with the aid of cubic spline functions. Statitistical significance of ages. 4. CODING AND FILE MANAGEMENT OF STRATIGRAPHIC INFORMATION. Introduction. Five basic types of files. Hay example as derived from the Sullivan database: Lower Tertiary nannoplankton in California. Partial DAT file for the Hay example. DAT files constructed by Guex and Davaud. Gradstein-Thomas database: Cenozoic foraminifera in Canadian atlantic margin wells. Characteristic features of Gradstein-Thomas database. Frequency of occurrence of taxa of cenozoic foraminifera along the northwestern Atlantic margin. Artificial datasets based on random numbers. 5. RANKING OF BIOSTRATIGRAPHIC EVENTS. Introduction. Hay's original method. Algorithmic version of Hay's original method. Uncertainty ranges for events in the optimum sequence. Other ranking algorithms. Conservative ranking methods. Three-event cycles. Higher-order cycles and pseudo-cycles. The influence of coeval events. 6. SCALING OF BIOSTRATIGRAPHIC EVENTS. Introduction. Scaling versus ranking. Statistical model for scaling of stratigraphic events. Artificial example. Computer simulation experiments. Normality test. Marker horizon option of the RASC method. Unique event option of RASC program. Binomial and trinomial models for scaling. Application of Glenn and David's trinomial model. Comparison of observed and estimated probabilities. 7. RANK CORRELATION AND PRECISION OF SCALED OPTIMUM SEQUENCE. Introduction. Rank correlation coefficients. RASC step model. Presorting and ranking by Harper. Precision of the scaled optimum sequence. 8. NORMALITY TESTING AND THE MODIFIED RASC METHOD. Introduction. Autocorrelation of the second-order differences. Unitary Associations and RASC methods applied to Drobne's alveolinids. Application of RASC and normality test to Palmer's database for the Riley Formation in central Texas. Modified RASC method. Application of modified RASC to the Gradstein-Thomas database. Frequency distributions of stratigraphic events. Application of modified RASC to Drobne's alveolinids. Comparison of range charts for Palmer's database. 9. EVENT-DEPTH CURVES AND MULTI-WELL COMPARISON. Introduction. Principles of correlation and scaling in time and comparison to composite standard method. Generalized description of the CASC method. Statistical selection of optimum spline-curves. Cross-validation method. Jackknife method. Computer simulation experiment for event-depth spline fitting with error analysis. Regional application of RASC and CASC. Application of RASC and CASC to Hibernia oilfield. Application of CASC to Palmer's database. Benthic foraminiferal zonation, central North sea. Integration of forminiferal and dinoflagellate datasets, Labrador shelf-grand banks. 10. COMPUTER PROGRAMS FOR RANKING, SCALING AND REGIONAL CORRELATION OF STRATIGRAPHIC EVENTS. Introduction. Summary of contents of the 12 modules of micro-RASC. List of decisions to be made by user of the RASC computer programs. Brief history of the development of RASC and CASC. References. Index.