Facies | Lithology | Description | Bioturbation | Depositional interpretation |
---|---|---|---|---|
Fm | Massive mudstone | Black–blue colour. Pyrite disseminated widely; few bioclasts. Aturia sp. and few microfossils | Absent | Fine-grained material decantation. Low energy deposition dominated by low energy, in an anoxic environment. Offshore (inner to outer platform) |
Fl | Laminated and bioclastic mudstone | Dark grey colour, abundant bioclasts, macroinvertebrates and microinvertebrates. Scarce presence of mudstone fraction. Transitional passage | Absent | Fine-grained material decantation and traction transport to a low energy environment which generated the accumulation of bioclasts. Shoreface to Offshore (inner platform) |
Ll | Laminated mudstone with plant debris | Brown–green colour. Plant debris and amber nodules. Transitional passage | Absent | Deposition via decanting in low-mid energy environment. “Shoreface” environment |
Htp | Heterolithic pelite | Dark grey colour, layered pelites alternate with thin layers of fine-grained sandstones and light-coloured limestones. Heterolithic levels are lenticular and are combined with flow ripple laminations. Inverse grading | Scarce | Decantation predominates over traction transport. Offshore transition to low Shoreface |
Hta | Sandy heterolithic levels | Dark grey, layer laminated shales alternate with thin layers of fine and mid-grained sandstones, light yellow in colour, with trough cross-bedding. Flaser bedding, in which cross-laminated sand contains mud streaks. Strata thickening upwards | Scarce, small burrows of cf. Skolithos isp. | Tractive process predominates over decantation process. Action of orbital flows in subaqueous environments, Lower to middle Shoreface |
Sm | Sandstone | Fine and mid-grained sandstones, brown–yellow in colour, with massive structure. Amalgamated sandstone levels with iron oxide specks | Abundant, Thalassinoides isp. and Planolites isp. | Tractive deposits of mid to high energy that lost their primary mechanical structure by synmixis and bioturbation process. Well-oxygenated substrate. High Shoreface |