Four measured sections of the Miocene Ar-Rajmah Group carbonate rocks in Cyrenaica, northeast Libya, each 25–75 m thick, spanning 94 km in length, and were sampled every 0.5 m for sequence stratigraphy, stable isotope (δ¹⁸O, δ¹³C) chemostratigraphy, X–ray fluorescence elemental analysis, and diagenesis. Petrographic study of the samples identified facies based on texture, grain types, mud content, cements, porosity types and amount, dolomitization, dedolomitization, gypsification, silicification, and recrystallization. Combining the sequence stratigraphy, chemostratigraphy, and petrography indicates that the Ar-Rajmah Group records two sequences separated by a sequence boundary and two different diagenetic patterns.

The petrographic analysis shows two distinct lithological, textural, and paragenetic patterns above and below a sequence boundary corresponding roughly to the middle Miocene Langhian-Serravallian boundary. The older Miocene interval (Langhian and older) is dominated by silicified dedolomitized bioclastic-rich, bryozoan, and red algal packstone beds. The younger Miocene interval (Serravallian and younger) is dominated by silicified and recrystallized oolitic grainstone, and microbial-bioclastic-oolitic grainstone.