Mapping & Petrography Appendices · appendix-14
Petrography — Sheet 14
The BL micrograph is dominated by very fine clay-rich matrix and is classified as mudrock under the Pettijohn framework. The reported 81 percent matrix strongly supports that broad class, but routine optical petrography cannot identify clay mineral species reliably; XRD would be required for mineralogical resolution.
SOURCE-LED TECHNICAL READING
Geological interpretation and evidential boundary
The BL micrograph is dominated by very fine clay-rich matrix and is classified as mudrock under the Pettijohn framework. The reported 81 percent matrix strongly supports that broad class, but routine optical petrography cannot identify clay mineral species reliably; XRD would be required for mineralogical resolution. Minor quartz, orthoclase, opaque grains and carbonate or clay cement should be separated from matrix through a documented point count, and fissility should be assessed at hand-specimen scale. The fabric is consistent with low-energy suspension deposition or distal sediment-gravity-flow fallout, yet depositional setting cannot be derived from matrix abundance alone. Bedding architecture, fossils and associated sandstone beds provide the necessary environmental context.
- Source
- Private geological appendix archive · controlled source record
- Location in source
- Source-linked record
- Image quality
- HD
- Record ID
- appendix-14
