GEO 403 Section 6 Part III

What are the two most widely used classification systems for carbonates?

Folk's Classification and Dunham's Classification

What are the three major constituents in Folk's Classification?

Carbonate grains (allochems), micrite, and sparry calcite cement

How many major classes of carbonate does Folk's Classification result in?

Four major classes

What is the special class of carbonate in Folk's Classification?

Reef rocks

What does Dunham's Classification focus on?

Relative abundance of allochems and micrite

What are the two aspects of depositional texture in Dunham's Classification?

Grain packing and relative abundance of grains to micrite, and depositional binding of grains

What is a key characteristic of carbonate rocks regarding diagenesis?

They are soluble and highly susceptible to diagenetic change

What are the four main processes involved in carbonate diagenesis?

Dissolution, cementation, replacement, and compaction

What is the effect of dissolution on carbonate rocks?

Formation of secondary porosity

What is drusy cement characterized by?

Sparry calcite crystals that line the pore walls of a limestone

What is the most common replacement process in carbonate diagenesis?

Calcite replacing aragonite

What does dolomitization refer to?

A diagenetic process where Mg-rich fluids replace calcite with dolomite

What is the chemical formula for dolomite?

CaMg(CO3)2

How can dolomite be recognized in thin section?

Using Alizarin Red, which turns calcite and aragonite red but does not affect dolomite

What texture does dolomitization leave behind?

A 'sugary' texture

What are stylolites?

Features resulting from pressure solution of significant volumes of carbonate

What is the role of rim cement in carbonate rocks?

Forms a fringe of equal thickness around grains or lines pores

What is the significance of primary interparticle porosity?

It is the porosity present in uncompacted ooid-peloid sand

What is the difference between primary and secondary porosity?

Primary porosity is original, while secondary porosity forms due to diagenetic processes

What does the term 'reef complex' refer to in Dunham's Classification?

Grains that were bound together at deposition

What is the significance of the depositional environment in Folk's Classification?

It helps describe carbonates in terms of energy levels and sorting

What is micrite?

A fine-grained carbonate sediment that is a major component in some carbonate rocks

What is the difference between sparry calcite and micrite?

Sparry calcite is coarser and crystalline, while micrite is fine-grained and non-crystalline