How are the Dunham and folk classification of carbonates different?

The differences between the classifications are mainly that Folk uses the relative percentages of grains and matrix, Dunham as well as Embry and Klovan use mud- versus grain-supported fabrics, and Wright uses a more genetic division into biological, diagenetic, and depositional fabrics.

What is the classification of carbonate?

The classification divides carbonates into two groups. Allochemical rocks are those that contain grains brought in from elsewhere (i.e. similar to detrital grains in clastic rocks). Orthochemical rocks are those in which the carbonate crystallized in place.

What are the two main criteria that the Dunham carbonate classification system is based on?

Two carbonate classification systems are in common use today, one by R.L. Folk and the second by R.J. Dunham . The Dunham system is based on depositional texture (that is, the amount of matrix surrounding the grains at the time of deposition).

What is a Rudstone?

A rudstone is a grain-supported carbonate rock containing grains larger than 2 mm. It is the coarse-grained version of a packstone or grainstone. The term rudstone is part of the extended Dunham Classification of carbonate rocks. [

How do you classify sandstones?

There are many different systems of classifying sandstones, but the most commonly used schemes incorporate both texture (the presence and amount of either interstitial matrix—i.e., clasts with diameters finer than 0.03 millimetre—or chemical cement) and mineralogy (the relative amount of quartz and the relative …

What are the components of carbonates?

Carbonate, any member of two classes of chemical compounds derived from carbonic acid or carbon dioxide (q.v.). The inorganic carbonates are salts of carbonic acid (H2CO3), containing the carbonate ion, CO2/3-, and ions of metals such as sodium or calcium.

Which mineral is a carbonate?

Carbonates. Carbonate minerals such as calcite and aragonite, the principle components of limestone and most phosphate and sulfate minerals will dissolve readily in 1 N HCl at room temperature.

What is the difference between Micrite and Sparite?

If one compares the two classifications, a Rock rich in carbonate mud is termed a micrite by Folk and a mudstone or wackestone by Dunham. Moreover, a Rock containing little matrix is termed a sparite by Folk and a grainstone or packstone by Dunham.

What is lime mudstone?

Note that a lime mudstone is a carbonate rock. A rock composed of siliciclastic mud but with carbonate cement should be treated as one of the fine-grained siliciclastic rocks (“shale”, claystone, mudstone, siltstone).

What are the three basic types of sandstones?

Based on hardness and color, four main types of sandstone can be recognized: (1) gray sandstone, (2) crystallized sandstone, (3) hard sandstone and (4) carbonate cemented sandstone.

What type of sandstone is the most mature?

Milky quartz, polycrystalline quartz grains, and quartz with undulatory extinction are less stable in the sedimentary environment than monocrystalline non-undulatory quartz. Thus, a sandstone consisting of monocrystalline quartz that does not show undulatory extinction is mineralogically the most mature.

What are examples of carbonates?

The most common are calcite or calcium carbonate, CaCO3, the chief constituent of limestone (as well as the main component of mollusc shells and coral skeletons); dolomite, a calcium-magnesium carbonate CaMg(CO3)2; and siderite, or iron(II) carbonate, FeCO3, an important iron ore.

What did Dunham use to classify carbonate rocks?

Dunham (1962) produced a classification of carbonate rocks that is based on depositional texture. He noted that there are several textural features that are especially useful in classifying carbonate rocks: (4) evidence of organic binding during deposition.

When did Robert Dunham invent the Dunham Classification system?

The Dunham classification system for carbonate sedimentary rocks was originally devised by Robert J. Dunham in 1962, and subsequently modified by Embry and Klovan in 1971 to include coarse-grained limestones and sediments that had been organically bound at the time of deposition.

Which is the best classification system for carbonate rocks?

Figure 1 Folk and Dunham classifications. The two commonest classification systems for carbonate rocks are those of Folk and Dunham. Folk’s classification uses combination forms of words describing the grains and words describing the cements. Dunham’s classification is based on the depositional fabric of the rock.

How are clastic rocks different from Dunham rocks?

The Dunham classification is similar to that of clastic rocks, in that it clearly shows the role of energy in sediment accumulation. The main distinction between rock types is based upon the relative abundance of allochems (framework grains) and matrix. Cement is treated as open pore space. Dunham Classification 5.