Molar tooth structure

Molar tooth structures are ribbon-like veins and nodules of calcite that are found widespread in Precambrian carbonate sedimentary rocks between approximately 2600 to 570 million years ago.

[6] The first documented observation of molar tooth structures was by Hilary Bauerman in 1884, during mapping of the Rocky Mountains for the Canada-United States border and the Geological Survey of Canada.

"Molar tooth structures are millimeter- to centimeter-scale microcrystalline ribbons and 'blobs' of calcite within argillaceous carbonate sedimentary rocks, sometimes reaching tens of centimeters in size.

The sediment matrix that molar tooth structures occur in is generally composed of finely crystalline calcite and dolomite, and fine-grained detrital quartz, feldspar, and clay minerals.

[2][1] The depositional environments that molar tooth structures are found in span from deep waters near storm wave base, to shallow intertidal.

Molar tooth structures in the late Mesoproterozoic Victor Bay Formation, Nunavut, Canada. Canadian penny for scale.
Molar tooth structures in the Neoproterozoic Båtsfjord Formation, Norway. Note deformation of the overlying beige bed, showing deflection around the molar tooth structure.
Molar tooth structures of the Proterozoic George Formation, BC, Canada. Arrow points at erosional surface, above which molar tooth structures occur as clasts, and below which they occur 'in place'.
Global distribution of molar tooth structures.