biogenic facies

geology

Also known as: shelly facies

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June 22, 2026

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In geology, a biogenic facies refers to a part of a rock layer where the fossil fauna or flora differs significantly from other parts of the same layer. Sedimentary rocks are formed in depositional environments, and the physical, chemical, and biological factors of these environments influence the accumulating sediments.12

Biogenic facies specifically represent accumulations of whole or fragmented shells and other hard parts of organisms. These are distinct from terrigenous facies (formed from eroded rock particles) and chemical facies (formed from inorganic precipitation). The study of facies helps geologists understand depositional environments and predict the distribution of resources like fossil fuels.2

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sedimentary facies
…transported to the depositional site; biogenic, representing accumulations of whole or fragmented shells and other hard parts of organisms; or chemical, representing inorganic precipitation of material from solution. As conditions change with time, so different depositional sites may change their shapes and characteristics. Each facies thus has a three-dimensional configuration…
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…transported to the depositional site; biogenic, representing accumulations of whole or fragmented shells and other hard parts of organisms; or chemical, representing inorganic precipitation of material from solution. As conditions change with time, so different depositional sites may change their shapes and characteristics. Each facies thus has a three-dimensional configuration…
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Silurian Period
Brachiopods
In contrast to shaley facies, shelly facies are represented by relatively shallow platform carbonates and clastic wedges with a retinue of mostly bottom-dwelling invertebrates. Among these, Silurian brachiopods (lamp shells) were especially abundant, diverse, and widely distributed, making them effective index fossils. A still-extant group, the brachiopods possess a pair…
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In contrast to shaley facies, shelly facies are represented by relatively shallow platform carbonates and clastic wedges with a retinue of mostly bottom-dwelling invertebrates. Among these, Silurian brachiopods (lamp shells) were especially abundant, diverse, and widely distributed, making them effective index fossils. A still-extant group, the brachiopods possess a pair…
Read More