Geological Mapping · mapping-4-32
Andesitic clast thin section from LP80 breccia
The analysed LP80 clast plots in the andesite field after QAP normalisation and shows a porphyritic, plagioclase-rich volcanic texture, supporting an intermediate volcanic source for that clast. It cannot classify the entire coarse body because a breccia may be polymictic and matrix composition may differ from clasts.
SOURCE-LED TECHNICAL READING
Geological interpretation and evidential boundary
The analysed LP80 clast plots in the andesite field after QAP normalisation and shows a porphyritic, plagioclase-rich volcanic texture, supporting an intermediate volcanic source for that clast. It cannot classify the entire coarse body because a breccia may be polymictic and matrix composition may differ from clasts. The petrographic report should state point-count method, alteration effects, whether groundmass was excluded from QAP recalculation and how quartz or feldspar were identified. A representative provenance interpretation requires counts from multiple clasts and the matrix across several stations. The plate therefore provides a secure clast-scale compositional datum and a hypothesis of andesitic source terrain, not a formation-wide compositional proof.
- Source
- Private mapping source vault · geological evidence record
- Location in source
- PDF page 78
- Image quality
- Standard
- Record ID
- mapping-4-32
