Southern Alps (geology)
Encyclopedia
The Southern Alps are a geological
subdivision of the European Alps
. The Southern Alps are the part of the Alps that are found south of the Periadriatic Seam
, a major geological faultzone
across the Alps. The Southern Alps contain almost the same area as the Southern Calcareous Alps, a geographical
subdivision of the Alps.
The rocks of the Southern Alps gradually go over in the "Dinarides" or Dinaric Alps
to the southeast. In the southwest they disappear below recent sediment
s of the Po basin
that are lying discordant on top of them.
tectonic plate, the area is a part of this plate. These are mainly Mesozoic
sedimentary rock
s, most of them limestone
s.
north of the Periadriatic Seam
, the geology of the Southern Alps is not characterized by nappe
s. Neither are high grade metamorphic rock
s common in the region. The Southern Alps are tectonically characterized by large scale thrusting
and folding
to the south, the dominant vergence
(direction of fold asymmetry) in the region is southward. As is also the case in the southern foreland of the Pyrenees
, thrusts in the Southern Alps are oriented along listric fault planes with relatively shallow decollement horizons
.
To the west, south of the Valle d'Aosta, the Southern Alps form a huge monocline
, up until the point that mantle
material of the Apulian plate crops out in what is called the Ivrea zone
.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
subdivision of the European Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
. The Southern Alps are the part of the Alps that are found south of the Periadriatic Seam
Periadriatic Seam
The Periadriatic Seam is a distinct geologic fault in Southern Europe, running S-shaped about 1000 km from the Tyrrhenian Sea through the whole Southern Alps as far as Hungary. It forms the division between the Adriatic plate and the European plate...
, a major geological faultzone
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...
across the Alps. The Southern Alps contain almost the same area as the Southern Calcareous Alps, a geographical
Geography
Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
subdivision of the Alps.
The rocks of the Southern Alps gradually go over in the "Dinarides" or Dinaric Alps
Dinaric Alps
The Dinaric Alps or Dinarides form a mountain chain in Southern Europe, spanning areas of Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Kosovo, Albania and Montenegro....
to the southeast. In the southwest they disappear below recent sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s of the Po basin
Po River
The Po |Ligurian]]: Bodincus or Bodencus) is a river that flows either or – considering the length of the Maira, a right bank tributary – eastward across northern Italy, from a spring seeping from a stony hillside at Pian del Re, a flat place at the head of the Val Po under the northwest face...
that are lying discordant on top of them.
Lithology
The Southern Alps are composed of material from the Adriatic or ApulianApulian Plate
The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period. The name Adriatic Plate is usually used when referring to the northern part of the plate...
tectonic plate, the area is a part of this plate. These are mainly Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s, most of them limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
s.
Tectonics
In contradiction to the Central Eastern AlpsCentral Eastern Alps
The Central Eastern Alps comprise the main chain of the Eastern Alps with its highest peaks, located between the Northern Limestone Alps and the Southern Limestone Alps, from which they differ in geological composition....
north of the Periadriatic Seam
Periadriatic Seam
The Periadriatic Seam is a distinct geologic fault in Southern Europe, running S-shaped about 1000 km from the Tyrrhenian Sea through the whole Southern Alps as far as Hungary. It forms the division between the Adriatic plate and the European plate...
, the geology of the Southern Alps is not characterized by nappe
Nappe
In geology, a nappe is a large sheetlike body of rock that has been moved more than or 5 km from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart. The resulting structure is a...
s. Neither are high grade metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
s common in the region. The Southern Alps are tectonically characterized by large scale thrusting
Thrust fault
A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger...
and folding
Fold (geology)
The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
to the south, the dominant vergence
Vergence (geology)
In structural geology, the vergence of a fold is the direction in which an antiform is inclined or overturned. The term vergence comes from the German vergenz, which means "overturn"....
(direction of fold asymmetry) in the region is southward. As is also the case in the southern foreland of the Pyrenees
Pyrenees
The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...
, thrusts in the Southern Alps are oriented along listric fault planes with relatively shallow decollement horizons
Decollement
Décollement is a gliding plane between two rock masses. In French, "décoller" means "to detach from" or "to rip off" and was first used by geologists studying the structure of the Swiss Jura Mountains, but is also known as a detachment zone. This is a structure of strata owing to deformation,...
.
To the west, south of the Valle d'Aosta, the Southern Alps form a huge monocline
Monocline
A monocline is a step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence.-Formation:Monoclines may be formed in several different ways...
, up until the point that mantle
Mantle (geology)
The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
material of the Apulian plate crops out in what is called the Ivrea zone
Ivrea zone
The Ivrea zone is a tectonic terrane in the Italian Alps, that consists of a steeply dipping piece of the Earth’s lower crust of the Apulian plate. The zone is named after the Italian city of Ivrea....
.