The key difference between allochthonous autochthonous and parautochthonous relies on the amount of displacement of the sediments from the site of origin. That is; the allochthonous refers to sediments that are found in a place that is remote to the site of origin. Meanwhile, autochthonous refers to sediments that are found in the native position or the site of origin, and parautochthonous refers to sediments having the character of intermediate between autochthonous and allochthonous.
Sediments are naturally occurring solid materials deposited on a location on the Earth. Sediments can be rocks, minerals, and remnants of plants and animals. Sediments can be deposited on the same location where they are originated, or they can be moved into a new location due to weathering or erosion. Sediments found in the soil are rich in nutrients. Hence, areas rich in sediments are rich in biodiversity. Allochthonous, autochthonous and parautochthonous are three terms that refer to the origin of sediments.
CONTENTS
1. Overview and Key Difference
2. What is Allochthonous
3. What is Autochthonous
4. What is Parautochthonous
5. Similarities Between Allochthonous Autochthonous and Parautochthonous
6. Side by Side Comparison – Allochthonous vs Autochthonous vs Parautochthonous in Tabular Form
7. Summary
What is Allochthonous?
Allochthonous is a geological term that refers to sediments or sedimentary rocks that are found in a location different from the location of origin. In simple words, allochthonous sediments or sedimentary rocks are found in a region that differs from where they originated. They may be deposited in a place remote from the site of origin due to weathering or erosion.
Figure 01: Allochthonous
What is Autochthonous?
Autochthonous is a term that refers to sediments that are found in the same place where they were formed or in a location very close to its site of deposition. Therefore, autochthonous sediments or autochthonous rocks are found in their native place.
Figure 02: Fossil
Furthermore, they are buried in a place without disturbance or disarticulation. Indigenous is a synonym of autochthonous. Many fossils are obviously autochthonous.
What is Parautochthonous?
Parautochthonous is a term that refers to sediments that show characters intermediate between autochthonous and allochthonous. Therefore, parautochthonous sediments or rocks are formed from materials that have been transported or displaced a relatively short distance.
What are the Similarities Between Allochthonous Autochthonous and Parautochthonous?
- Allochthonous, autochthonous and parautochthonous are three terms that are used in geology to describe the origin of sediments.
- Parautochthonous refers to the intermediate character of autochthonous and allochthonous.
What is the Difference Between Allochthonous Autochthonous and Parautochthonous?
Allochthonous refers to sediments that are found remote from the place of origin, while autochthonous refers to the sediments that are found in the same location where they have formed. Parautochthonous, on the other hand, refers to sediments that have been transported or displaced a relatively short distance and have an intermediate character of allochthonous and autochthonous. So, this is the key difference between allochthonous autochthonous and parautochthonous. The sediments are displaced in allochthonous, but in autochthonous, the sediments are not displaced from the site of origin. However, in parautochthonous, sediments are displaced a relatively short distance.
Summary – Allochthonous Autochthonous vs Parautochthonous
Allochthonous, autochthonous, and parautochthonous are three terms used in geology to refer to the origin of sediments. Allochthonous refers to sediments that are buried or found in a place remote from the site of formation. Autochthonous sediments are buried in a place where they have formed or originated without disturbance or disarticulation. Parautochthonous refers to the sediments having a character intermediate between that of autochthonous and allochthonous. Parautochthoonous sediments have displaced a relatively short distance from the place of origin. Thus, this is the summary of the difference between allochthonous autochthonous and parautochthonous.
Reference:
1. Bird, John M. “Allochthon.” SpringerLink, Springer, Berlin, Heidelberg, 1 Jan. 1987, Available here.
2. “Parautochthonous: Meaning of Parautochthonous by Lexico.” Lexico Dictionaries | English, Lexico Dictionaries, Available here.
Image Courtesy:
1. “Thrust system en” By Woudloper at English Wikipedia – Transferred from en.wikipedia to Commons by MagnusA using CommonsHelper (Public Domain) via Commons Wikimedia
2. “Seymouria Fossil” By Sanjay Acharya – Own work (CC BY-SA 4.0) via Commons Wikimedia