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Asymmetric, pendant cements are considered good indicators for early lithification in the vadose zone. In the present study, asymmetric cements are recorded in thin-sections of a Lower Jurassic limestone from the Traras Mountains (northwest Algeria). Geopetal fabrics, however, indicate that these seemingly “pendant cements” are, in some places, oriented upwards, i.e., they have grown in the opposite direction from that expected, or they grew from grains towards the pore centers. These observations disprove their origin as gravitational cements precipitated from pendant water droplets on the undersides of grains as in the vadose zone. In contrast, a formation in the marine phreatic zone seems more probable. Under high-energy conditions, and after an early lithification stage with isopachous cements in the subtidal zone, strong tidally driven horizontal pore-water flow allowed sufficient seawater to pass through the slightly cemented but still highly permeable rock. Those grain sides, which were oriented towards the pore center, where faster flowing water prevailed, were more exposed to CaCO3-supersaturated percolating seawater and therefore the cements precipitated here show their greatest thickness. In relatively more protected areas around the margins of the pores, asymmetric cements are rarely developed. The resulting rock exhibits an unusual, heterogeneous cementation with preferential centripetal nucleation areas.

A Carnian dasycladacean florula, consisting of five species belonging to four genera, is described from the Jiapeila formation of the Qambdo District in Eastern Tibet. Most species are identical or similar to dasycladaceans from the western parts of the Tethys, especially the Western Carpathians. New species (Physoporella jomdaensis n.sp.,Salpingoporella? tibetica n.sp.) characterize the special aspect of the Tibetan florula. Of general interest is the first evidence of an endospore reproductive structure, which was found in situ within the thallus ofGyroporella cf.G. vesiculifera GUMBEL,Gyroporella possibly represents the vegetative stage ofAtractyliopsis PIA. The microfacies of the algal limestones is characterized by poorly compacted oolitic grainstones with abundant aggregate grains (lumps) and by compacted micrite-bearing packstones. Cement fabrics indicate diagenesis within the freshwater phreatic zone. The depositional environment can be interpreted as a shallow carbonate platform area adjacent to oolitic shoals.