Mapping & Petrography Appendices · appendix-19
Petrography — Sheet 19
The Pettijohn diagram translates the BS proportions into the lithic-wacke field by combining framework composition with matrix content. Its location should be recalculated from the documented point count and accompanied by an error envelope, especially because matrix thresholds determine whether ‘wacke’ is appropriate.
SOURCE-LED TECHNICAL READING
Geological interpretation and evidential boundary
The Pettijohn diagram translates the BS proportions into the lithic-wacke field by combining framework composition with matrix content. Its location should be recalculated from the documented point count and accompanied by an error envelope, especially because matrix thresholds determine whether ‘wacke’ is appropriate. The relative lithic, feldspar and quartz fractions can inform provenance only after alteration, pseudomatrix and unstable fragments are handled consistently. The diagram therefore standardises nomenclature but does not establish source terrane or turbidite subenvironment by itself. Confidence rises when the plotted classification agrees with thin-section texture, hand-specimen description and multiple beds within a measured stratigraphic section.
- Source
- Private geological appendix archive · controlled source record
- Location in source
- Source-linked record
- Image quality
- HD
- Record ID
- appendix-19
