euxinicadj.

1937 Bull. Amer. Assoc. Petroleum Geologists 21 1115 Analyses show the presence in the Black Sea muds of a relatively high proportion of organic matter and various investigators have seen in this fact a possible source for the formation of materials analogous with the black shales of some geological formations... Van der Gracht proposes the term euxinic facies (Pontus Euxinus = Black Sea) for deposits of this type.

1949 F. J. Pettijohn Sedimentary Rocks xiv. 458 The true euxinic sediments are exclusively marine and generally rather deep-water.

1963 D. W. Humphries & E. E. Humphries tr. H. Termier & G. Termier Erosion & Sedimentation xi. 232 The preservation of organic matter in these environments tends to produce hydrocarbons. Such environments are known as ‘euxinic’ and have been known for a long time in the Black Sea.

1970 R. M. Black Elements Palaeontol. xix. 302 Anaerobic bacteria are invoked to explain occurrences of euxinic shales.

1979 Nature 25 Oct. 667/1 The ‘euxinic events’ responsible for this facies pattern are all characterised by saline spills or brine invasions, which in turn led to a midwater halocline and a meromictic basin.

1985 Nature 3 Jan. 13/1 The Hangenberg event, towards the close of the Famennian, was another euxinic black shale event in Europe.