Sedimentary Rocks

• Carbonatic Rocks
• Evaporite rocks
• Terrigenous Rocks
Grain Size
Terrigenous Rocks
Packing
Roundness
Sorting

• Weathering

Turbidite

• Turbidites

Fossils

• Ammonites
• Bivalves
• Brachiopods
• Gastropods
• Trilobites

Sedimentary Minerals

• Anhydrite
• Baryte
• Chalcedony
• Gypsum
• Glauconite
• Magnesite

Texture

• Allochem
• Carbonatic Matrix
• Dolomitization
• Syntaxial Overgrowthn

Rocks

• Ammonitico Rosso
• Arkosic Sandstones
• Bioclastic Grainstone
• Oolitic Ironstone
• Breccia
• Conglomerate
• Encrinite
• Lithic Arenite
• Mudstone
• Oolite
• Orthoconglomerate
• Radiolarite
• Wackestone

Ammonitico Rosso

The name Ammonitico Rosso was first used in Northern Italy (Pilla, 1847) to indicate pelagic limestone which was widespread in the Jurassic Tethys Ocean. This limestone is characteristically gray to reddish in color and is usually rich in macro- and micro-fossils.

The Rosso Ammonitico is traditionally defined, as condensed, pelagic, red, nodular limestone. The lithology exhibits nodular light-reddish nodules incorporated in an even more reddish, argillaceous matrix, mainly formed by condensed residues. The latter, more marly parts of the layers form the orange colour after weathering. Corroded ammonoids typically dominate the macrofauna, followed by aptychi, belemnites and brachiopods, best visible on bed surfaces. Microfacies types occur with biogenic-rich bioturbated mudstones, radiolaria-mudstones and foraminifera-radiolaria-wackestones. The Rosso Ammonitico is a pelagic-hemipelagic facies formed on submarine highs with increased water currents at water depths from approx. 100 m down to 300 m.

Many sedimentary bodies, mainly Jurassic in age, in Southern Alps, Central appennes, Sicily have been referred to informal lithostratigraphic units named as "rosso ammonitico". In soma place, a Geographical denomination has been added in order to distinguish one from the other (e.g Rosso ammonitico Veronese, Rosso Ammonitico Lombardo etc.).
Red, nodular, pelagic limestones commonly, but not necessarily, containing ammonite moulds have been described as the rosso ammonitico facies (or Ammonitico Rosso according to the Anglo-saxon usage), irrespective of age. This dual use generated some confusion: in some place green-gray, non nodular and even ammonite-free sediments are included in a lithostratigraphic unit informally named rosso ammonitico; on the contrary, pelagic red limestones whit ammonite moulds have been given a lithostratigraphic name that does not make any reference to Rosso Ammonitico.

After many years of research it was clear that there is not a single "Rosso Ammonitico" facies. Rosso Ammonitico should basically be characterized by red colours, presence of ammonite moulds, and nodular structure, although gray or green coluors also occur and ammonites may be lacking. The nodular structure derives from the juxtaposition of cm-sized, rounded portion of lighter coloured, nearly pure limestones, and of so-called matrix consisting of dark red marls or marly limestones. The lack of carbonate grains typical of shallow platform and the scarcity of terrigenous sediments are common feature of the pelagic Rosso Ammonitico. Most of the sediments is biogenetic, being represented by the skeletal remains of both planktonic and benthic organisms (nannofossils, calcispheres, foraminifers, radiolarians, bivalves shell, gastropods and echinoderms). Average sedimentation rates are consequently very low, of the order of mm/Ky, and stratigraphic discontinuities frequent.

Because no present day analogue exists for Rosso Ammonitico facies, the paleoenviromental and paleobathymetric interpretation of this peculiar facies is still uncertain. In spite of this, on the basis of univocal geological evidence, all author agree on many point such as:

1) Rosso Ammonitico is the typical product of condensed sedimentation on top of blocks resulting from rifting and drowning of carbonate platforms below the photic zone
2) Being detached from continent and surrounded be deeper basins, the only source of sediments is the slow pelagic rains, plus benthic components.
3) Current were intermittently active, as documented by intraclasts, erosional discontinuities and traction laminae.
4) Bottom conditions were oxygenated, as the red Colour of the rock indicates.

Ammonitico Rosso lithofacies from Late-Early Jurassic (Early Toarcian) of northern Lombardy (Italy-Southern Calcareous Alps). Red nodular marly limestone to marl. From Wikipedia.

Normal Foults in the Rosso Ammonitico from Appennines. Photo of Rodolfo Carosi.

Ammonite fossils in Rosso Ammonitico Lombardo. Photo of Stefano Cuzzilla.

Ammonite fossil in Rosso Ammonitico Lombardo.

Ammonite fossils in Rosso Ammonitico Lombardo. from "L'angolo della Geologia".

Bibliography

• Alexander Lukeneder: The Biancone and Rosso Ammonitico facies of the northern Trento Plateau (Dolomites, Southern Alps, Italy). Annalen des Naturhistorischen Museums in Wien, Serie A 113.
• Martire. L., Clari. P., Lozar. F., Pavia. G. (2006): The Rosso Ammonitico Veronese (Middle-Upper Jurassic of the Trento Plateaux): A proposal of Lithostratigraphic ordering and Formalization. Rivista Italiana di Paleontologia e Stratigrafia.
• Préat. A., Morano. S., Loreau.J.P., Durlet. C., Mamet.B. (2006): Petrography and biosedimentology of the Rosso Ammonitico Veronese (middle-upper Jurassic, north-eastern Italy)

Photo

ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonites and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)	brachiopods (the square section) and Ammonite fragments. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	brachiopods (the square section) and Ammonite fragments. Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Big Ammonite fragment (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Big Ammonite fragment (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)	Big Ammonite fragment (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite and Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite fragments (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite section (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 10x (Field of view = 2mm)
Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 10x (Field of view = 2mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite section (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite section (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite sections (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite section (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. XPL image, 2x (Field of view = 7mm)
Ammonite (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	small Ammonites. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	small Ammonites. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
Ammonite section (replaced by Calcite). Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	small Ammonites. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	Gastropod section. Rosso Ammonitico from Italian Alps. PPL image, 10x (Field of view = 2mm)
Gastropod section. Rosso Ammonitico from Italian Alps. XPL image, 10x (Field of view = 2mm)	small Ammonites. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)	small Ammonites. Rosso Ammonitico from Italian Alps. PPL image, 2x (Field of view = 7mm)
small Ammonite. Rosso Ammonitico from Italian Alps. PPL image, 10x (Field of view = 2mm)	small Ammonite. Rosso Ammonitico from Italian Alps. PPL image, 10x (Field of view = 2mm)	small Ammonite. Rosso Ammonitico from Italian Alps. PPL image, 10x (Field of view = 2mm)