What is the Difference Between Allochthonous Autochthonous and Parautochthonous?

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The terms allochthonous, autochthonous, and parautochthonous are used to describe the origin and location of sediments and rocks in relation to their site of origin. Here are the differences between these terms:

  1. Allochthonous:
  • Sediments or rocks that are found in a place that is remote from their site of origin.
  • Typically deposited by water, wind, or ice.
  • Not native to the area they are found in.
  1. Autochthonous:
  • Sediments or rocks that are found in their native position or site of origin.
  • Not displaced from their site of origin.
  • Formed from molten lava.
  1. Parautochthonous:
  • Sediments or rocks that have been transported or displaced a relatively short distance.
  • Intermediate character between autochthonous and allochthonous.
  • Formed by the folding of other rocks.

In summary, allochthonous sediments or rocks are those that have been transported from another location, typically by water or wind, and are not native to the site where they are found. Autochthonous sediments or rocks are those that remain in their native position or site of origin, while parautochthonous sediments or rocks have been transported or displaced a relatively short distance and display an intermediate character between autochthonous and allochthonous.

Comparative Table: Allochthonous Autochthonous vs Parautochthonous

The following table summarizes the differences between allochthonous, autochthonous, and parautochthonous sediments:

Term Meaning Formation Location
Allochthonous Sediments found remote from the place of origin Transported by water or wind Not native to
the location
Autochthonous Sediments found in the native position or site of origin Formed in situ, such as carbonate precipitation in a lacustrine facies Native to the
location
Parautochthonous Sediments with an intermediate character between autochthonous and allochthonous Formed by the folding of other rocks Intermediate

Allochthonous sediments are found in a place that is remote from their site of origin, while autochthonous sediments are found in their native position or site of origin. Parautochthonous sediments have an intermediate character between autochthonous and allochthonous sediments, as they are formed by the folding of other rocks.