It is composed by 230 meters of thick layers of marlstone
intercalated with limestone.
Varicoloured mixed carbonate-siliciclastic rocks are represented by cement-supported silt- and sandstone, and by dolomitic marlstone
and dolostone including siliciclastic material (Fig.
2000) is a mixed scleractinian-siliciclastic succession, reflected by the ichnospecific diversity of the borings by bivalves assigned to Gastrochaenolites ispp., mainly in large colonial scleractinian corals and strombid gastropods, and by burrows (Ophiomorpha, Palaeophycus and Thalassinoides) in sandstones and so-called marlstones
(Pickerill and Donovan 1997; Pickerill et al.
On the basis of the identification of bentonites, we assume that the deep-sea marlstone
in the Ohesaare section correlates with the shallow-water Rumba Formation.
To the east of that region, the main part of the Oandu Stage consists of various marlstone
and argillaceous limestone comprising the Hirmuse Formation (Fig.
The potential source rocks of paleo-oils for the gases and the associated solid bitumen include Lower Cambrian black shale ([Cam.sub.1]), Lower Silurian Longmaxi Fm ([S.sub.1]l) mudstone and shale, Upper Permian Longtan Fm ([P.sub.3]l) or isochronous Wujiaping Fm ([P.sub.3]w) mudstone, shale, and marlstone
, and Upper Permian Dalong Fm ([P.sub.3]d) or isochronous Changxing Fm ([P.sub.3]ch) shale and mudstone [24-26].
The overlying formation is the Xiloutian (Genjiajie) Formation, whose sediments are mainly gray calcareous shale interlayered with light gray marlstone
The Upper Ordovician is represented by reef and shoal facies packstone and bioclastic limestone and slope facies limestone and marlstone
 The Silurian to the Carboniferous sequence consists of marine sandstones and mudstones.
Currently, the rock types of oil shale in the world are mainly shale (mudstone), marlstone
and carbonate .
The organodetrital limestones in the lowermost part of the Blidene Formation are replaced upwards by argillaceous marlstone
or by marlstone
with thin interbeds or nodules of limestone.
These dolomites were unconformably overlain by middle early Valanginian nannofossil marlstone
with calpionellids and very low amounts of foraminifers (Jansa et al., 1988).
It consists of mudstone, sandstone, marlstone
, coalbeds, and oil shales.