SUMMARY

Sandstones in the Lossiemouth borehole have subarkosic and sublitharenitic compositions, and are thought to have been derived from a southerly source. Early diagenesis in sandstones took place in low ionic concentration waters which generated dissolution secondary porosity and formed kaolinite. Grain-coating illite/smectite and calcite are locally abundant early diagenetic cements. Illite and K-feldspar authigenesis post-dates kaolinite formation and may be associated with mineralisation. Quartz overgrowth is the final stage of diagenesis observed. Shales have an illite + chlorite mineralogy interpreted to be of detrital origin.