What is an alpine cleft in geology ?

Alpine cleft (or alpine fissure) : definition

Alpine fissures are open fractures in which remarkable crystallizations have formed, in particular of quartz, albite, epidote, chlorite, hematite, axinite, and adularia. Their name comes from the fact that they are found in large numbers in the Alps, and more particularly in the Mont-Blanc Massif, while they are very rare in other regions. Outside the Alps, they are only known in the subpolar Urals and in the Himalayan massif. These crystal slots are not very thick (with a thickness of a few centimeters to 1.20 m) and of weak extension (decimetric to decametric). They are found in granites as well as in metamorphic rocks.

These alpine clefts are of metamorphic origin and were born during the formation of the Alps, between -19 and -40 million years ago. At that time, the compressed rocks underwent a metamorphism of green schist facies which caused the opening of cracks and the circulation of aqueous metamorphic fluids rich in silica, aluminum, potassium, etc... These fluids were able to deposit their mineral charge and develop magnificent crystallizations in the open spaces formed by these alpine fissures (or clefts).

ReCaptcha

This service is used to secure web forms of our website and required if you want to contact us. By accepting it you agree to Google's privacy policy: https://policies.google.com/privacy

Google Analytics

Google Analytics is a service used on our website that tracks, reports traffic and measures how users interact with our website content in order for us to improve it and provide better services.

Facebook

Our website allows you to like or share its content on Facebook social network. By activating and using it you agree to Facebook's privacy policy: https://www.facebook.com/policy/cookies/

YouTube

Integrated videos provided by YouTube are used on our website. By accepting to watch them you agree to Google's privacy policy: https://policies.google.com/privacy

Twitter

Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy: https://help.twitter.com/en/rules-and-policies/twitter-cookies

PInterest

Our website allows you to share its content on PInterest social network. By activating and using it you agree to PInterest's privacy policy: https://policy.pinterest.com/en/privacy-policy/