Stromatolite Kuban Basin Russia [Freshwater Eocene]

Freshwater Stromatolite Kuban Basin Russia

This stromatolite from the Kuban Basin, Caucasus, Russia, is from an area of diverse geology. This is a dynamic freshwater, calcite stromatolite from 34-55 Ma (Eocene).

Specimen Details

• Size: 55mm X 48mm x 7mm
• Weight: 32 grams
• What's included: Ships with a Certificate of Authenticity, tag, tag stand, and information.

Stromatolite Formation Process

Cyanobacteria grow as mats in shallow, still water. Photosynthesis in the bacteria depletes carbon dioxide in the surrounding water, making it less acidic, thus initiating the precipitation of calcium carbonate. Distinctive layers are created as calcium carbonate is precipitated over the growing mat of bacterial filaments. Sediments such as spherules from volcanic ash also become trapped in the sticky mucilage layer surrounding the bacterial colonies. As the colony grows through the sediment, new layers form, creating a stromatolite.

Geological Context

The Eocene was a “greenhouse” era in the Kuban Basin with high CO2, warm temperatures, and shallow water favoring bacterial growth. Extensive volcanic activity in the Kuban Basin, Russia, contributed to the growth of this stromatolite. Andesite basalt, rich in plagioclase, contributed calcium to the warm freshwater, facilitating bacterial-initiated calcite crystal growth and precipitation.

Stromatolite Layers

• Calcite (white)
• Calcite with iron (yellow)
• Calcite with variable levels of volcanic spherule inclusions (dark bands)

Environmental Significance

This stromatolite reveals the niche environment where it grew, possibly in a swamp, a slow-moving stream, or a stagnant pond, right against a well-vegetated shoreline. The small plant branches are perpendicularly aligned to the stromatolite’s horizontal layers. Fossil stromatolites enclosing structurally preserved land plant remains are rare.

Fossilized Plant Remains

The vertical elements are fossilized remains of plant stems that grew contemporaneously with the stromatolite. In the Eocene, the cyanobacteria that formed the stromatolite layers and the plants were all reaching up toward sunlight.

Stromatolite Composition

Traditionally, stromatolites are primarily composed of calcite (calcium carbonate), which is the most common type of carbonate found within their layered structures. However, depending on the environment, they can also contain other carbonate minerals like aragonite and, in some cases, dolomite.

Key Points about Carbonates in Stromatolites

• Dominant mineral: Calcite is the primary carbonate mineral found in most stromatolites.
• Other potential carbonates: Aragonite and dolomite can also be present in certain stromatolite formations.
• Formation process: Cyanobacteria, the primary organisms responsible for building stromatolites, trap sediments and precipitate calcium carbonate from the surrounding water, leading to the layered carbonate structure.

Key Points about the Eocene Epoch

• Part of the Paleogene Period: The Eocene is considered the second epoch within the Paleogene period, which is itself part of the Cenozoic Era.
• Meaning of the name: "Eocene" comes from Greek words meaning "dawn of the new," referring to the emergence of early forms of modern mammals during this time.
• Climate: The Eocene was generally a hot and humid period with high levels of carbon dioxide in the atmosphere.
• Notable life forms: During the Eocene, early ancestors of modern mammals like horses, primates, and whales began to appear, alongside diverse plant life.

Key Points about the Eocene Atmosphere

• High CO2 levels: Considered the primary factor contributing to the warm Eocene climate, with CO2 concentrations likely exceeding 500 ppm, significantly higher than today's levels.
• Warm global temperatures: Due to the elevated CO2, the average global temperature during the Eocene was considerably warmer than today, with some estimates placing it at least 14 degrees Celsius higher.
• Minimal ice caps: The high temperatures likely resulted in minimal polar ice caps, with even the poles experiencing relatively warm conditions.
• Impact on ecosystems: The warm and humid climate supported lush vegetation, including dense forests, with diverse plant and animal life adapted to the high temperatures.

Buy This Terrific Specimen for Your Collection

This is a terrific specimen to help you learn more about freshwater stromatolites and realize the importance of the Eocene, climate, and life at this geologic time period. If you do not have a stromatolite from this location, add it to your stromatolite collection today!