authigenic


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authigenic

[¦ȯ·thə¦jen·ik]
(geology)
Of constituents that came into existence with or after the formation of the rock of which they constitute a part; for example, the primary and secondary minerals of igneous rocks.
References in periodicals archive ?
As the authigenic calcite precipitates during the spring/summer photosynthetic bloom, the isotopic records reflect the equilibrium conditions (temperature and isotopic ratio in lake water, when local evaporation and direct precipitation have their strongest isotopic effects; e.
Indirect evidence suggests that bacterial processes were important during the deposition and early diagenesis of most oil shales that lead to formation of authigenic sulfide and carbonate minerals.
Concentric crystals of authigenic silica and chalcedony having some similar features with the above described chalcedony nodules with concentric structure and irregular outlines and embayments (Fig.
Therefore, the dating of dolomitization events and the paragenetic sequence of diagenetic processes is complicated and we are able to propose only some preliminary interpretations of the diagenetic setting of the distinguished dolomite types and authigenic precipitations (Fig.
Authigenic silicate minerals, where present in lower strata, are invariably represented by glauconite with shifts to chamosite only in intervals where the rock is lutitic.
However, the SEM studies show the presence of authigenic calcite aggregates in semi-coke sediments.