• "The GBZ was deposited within a largely closed marine basin with restricted water circulation (Zorn 1971, Rieber et Sorbini 1983, Bernasconi, 1994). The basin was enclosed by carbonate platforms. The fine-grained sediments and missing evidence of reworking, the mostly complete preserved vertebrate skeletons which are not oriented indicate that there was at most a weak current at the bottom of the basin and that the sediments were deposited below wave base. The water depth of the basin is estimated to have been 30 to 100 m with a gradual deepening through time. The undisturbed lamination of the GBZ rocks and a lack of autochthonous benthos point out that the basin in which the GBZ generated had a stable stratification of the water column and that the bottom water was almost always anoxic and rich in H2S. The common remains of highly marine animals, primarily pelagic fish, ichthyosaurs, ammonoids, and daonellids prove that the surface waters had normnal salinity and was at least periodically connected to the waters of the Triassic Paleotethys." (translated from Rieber, 2000)

•Sequence Stratigraphy: looks and sounds like the maximum flooding interval of a transgressive systems tract

• "The Grenzbitumenzone [GBZ] of the Tessiner Kalkalpen is an alternation of dolomite beds of various thickness (3 up to 50 cm), numerous, thinner layers of finely laminated, black bituminous shales (Schwarzschiefer), and few, up to several centimeters thick, volcaniclastic interbeds (volcanic ashes). [...] The beds of the more or less laminated dolomites make up about 80% of the total thickness of the GBZ. Depending on the degree of weathering and on the content of organic matter (up to 12 weight %), the dolomite beds are dark grey, dark brown to light beige. In freshly-mined condition, in the galleries of the former mines, they are almost black (high organic matter content) or dark to medium grey. The the original carbonate mud is completely dolomitized. There is no evidence of other carbonate phases. The laminae of the mostly parallel and continuous fine lamination vary in thickness from 0.1 to 5 mm. In most cases the lamination is caused by a rhythmic change of the content of dolomite, clay minerals, and organic matter. However, in dolomite-rich laminae also graded bedding may be observed occasionally. [...] The black shales contain no or at most few carbonate. The content of organic matter ranges from 10 up to 40 weight %. The fine lamination of freshly-mined shale is well visible only in thin sections. Partly weathered, the black shale delaminates into thin (mostly less than 1 mm) laminae [...]. The lamination is caused by a change of organic matter, clay minerals, and quartz. The quartz is mainly biogenic. Radiolarians are very common and partly form small laminae of silica in the black shales." (translated from H.-P. Rieber, 2000, in D. Meischner (ed.) Europäische Fossillagerstätten, German edition)