Glauconite radiometric dating

Within the evolved to highly evolved stages, the granular substrate cracks and is later filled.

This process greatly increases a deposits potential for radiometric dating using the century, several marl companies were established along the nutrient rich inner coastal plain.

In the structure of mica, two silica tetrahedral sheets face one central octahedral sheet.

The tips of the tetrahedra point toward the central unit, and the three sheets are combined into a single layer with a suitable replacement of OH and O.

Regardless of how the phyllosilicates degraded they must have had a high positive charge deficiency lacking a sufficient amount of cations within the octahedral layer.

This charge deficiency would have been balanced temporarily by highly mobile and abundant marine cations like magnesium, potassium, calcium and sodium until they could be replaced by structural iron (Mc Conchie, 1979).

Often glauconite pellets fracture and are then later filled in by a newer generation with some compositional differences (Krinsley and Pye, 2005).

This process of fracturing and filling creates the opening and closing of the system.

For example these processes could end with changes in Eh or abundance of Fe.

The maturity can be seen in the evolution of the grains morphology which are sub-divided into four morphological stages: nascent, slightly evolved, evolved, and highly evolved.

Recent studies have estimated that it may take hundreds of thousands of years in order for highly evolved glauconites to form.

Formations such as the Navesink and Hornerstown are abundantly fossiliferous and contain key index fossils such as the oyster .

The mineral glauconite is a dioctahedral layer potassium phyllosilicate made up of complex potassium, iron, aluminum silicates with greater than fifteen percent iron (III) oxide.