Middle Marker Chert Oldest Sedimentary Rock 
Brand : Jensan Scientifics LLC
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The Middle Marker horizon is the sedimentary unit belonging to the base of the Hooggenoeg Formation, located in the Barberton Greenstone Belt, South Africa. This formation is a part of the Onverwacht Group and is among Earth's oldest identified sedimentary horizons. It is the oldest horizon in this Greenstone Belt, and detrital zircon dating establishes its age at a conservative 3.472 Ga.
What makes this chert so special is that it contains kerogen-like particles that are rich in organic carbon. It is called a "clotted" carbonaceous chert because the proportion of silica to carbon gives it a clotted appearance on the centimeter scale.
The "Middle Marker" derives its name from its being an extraordinarily thin, approximately 10-meter thick, geologic layer in the middle of other complexes that are part of the diverse Barberton Greenstone Belt. The Middle Marker Complex is unique for its dispersed chert seams. The chert formed from sediments deposited in an isolated basement that did not experience energetic tidal fluctuations. Instead, light cross-bedding indicates that sedimentation occurred in shallow water at slow and variable rates.
The Middle Marker chert has minimal volcaniclastic sediment layering, evidence of waning volcanism during its formation. The specimen also displays minor trough-bedding and cross-stratification. In addition, a wavey line structure can be seen, appearing as a filament or wisp. This microstructure occurs as fragments work their way into the Middle Marker chert sedimentary layers. The lines appear similar to crinkly biofilm laminations.
Middle marker black chert is highly important because microfossil remnants have been found in this horizon. It could represent material that contains the second oldest life on Earth. The Middle Marker horizon includes biofabrics and microbial mats that predate stromatolites, which are cyanobacteria mats.
Specimen size: 45mm L X 27mm W X 25mm D, Weight 63.7 grams; Ships with Certificate of Authenticity, tag and tag stand, and a copy of relevant scientific articles included. Display base and photo cube not included.
In-color 3 X 5 inch microscopy photo (shown) included. In situ, color photographs are included with the order.
This material was legally collected and obtained in a materials trade with a scientific institution.
Add this intriguing, limited, rare specimen to your geological early Earth collection today.