Mylonite - Formation of Mylonite - Classification of Mylonites

Explore the fascinating world of Mylonites, unique metamorphic rocks formed under intense pressure and deformation deep within the Earth's crust. In this video, we dive into the formation process of mylonites, where rocks undergo ductile deformation and recrystallization in tectonic shear zones, creating their characteristic fine-grained, foliated texture.
We'll also discuss the classification of mylonites, from protomylonites to ultramylonites, and explore how these classifications reflect the degree of deformation and recrystallization. Additionally, you'll learn about the different types of mylonites based on mineral composition, including quartzofeldspathic mylonites, phyllonites, carbonate mylonites, and more.
Whether you're a geology enthusiast, a student, or just curious about Earth's dynamic processes, this video provides a detailed look at the significance of mylonites in understanding tectonic history, crustal deformation, and mineral resources. Don't forget to like, share, and subscribe for more geology content!

[@rogerhanson3468]

Nice explanation of mylonite, with the very last part mentioning association metals, if mylonite is a transition material then One would assume it would have a greater association with PPG or REE's , ALL that was mentioned was AU,

[@professionalgeologyclub]

Mylonite is a fine-grained, foliated metamorphic rock formed by intense ductile deformation under shear stress, often in fault zones or shear zones. The process of mylonitization involves recrystallization and mechanical deformation, leading to a reduction in grain size and the development of a distinct foliation.
Mylonite's mineralogical composition depends on the protolith (original rock type) and the specific deformation conditions, such as temperature and pressure. It can form from various rock types, including igneous, sedimentary, or metamorphic rocks. Because of this variability, mylonites are sometimes associated with economic mineral deposits, depending on the geological setting.
Economic Metal Associations
Gold (Au):
Gold is frequently mentioned because mylonites often form in shear zones, which are common pathways for hydrothermal fluids. These fluids can deposit gold and other sulfide minerals in fractures and veins associated with the deformation.
For example, gold is common in orogenic gold deposits, which are often linked to mylonitized shear zones.
Platinum-Group Elements (PGE):
Mylonites derived from ultramafic rocks or those near magmatic systems may show associations with PGE minerals (e.g., platinum, palladium). Such associations are less common than gold but can occur in specific tectonic environments.
Rare Earth Elements (REEs):
While REE enrichment is not typically associated with mylonite itself, REEs might be concentrated in specific protoliths, such as granites or carbonatites, that undergo mylonitization. These elements may be mobilized and redeposited by hydrothermal fluids in fractures or zones of intense deformation.
Other Metals (e.g., Cu, Pb, Zn, Ag):
Hydrothermal systems along shear zones may also transport and deposit base metals, such as copper, lead, and zinc, or precious metals like silver. These are often found in polymetallic deposits.
Why Mention Only Gold?
Gold is highlighted because of its strong association with shear zones and mylonites in orogenic gold systems, making it one of the most economically significant metals in these settings. REEs and PGE associations, while possible, are more dependent on the protolith and broader geological setting than on the mylonite itself.
Assumption About REEs and PGEs
If mylonite is a "transition material," as you suggest, one might expect it to show a greater association with REEs or PGEs in specific tectonic environments, especially in zones of magmatic activity or where REE-rich or ultramafic rocks serve as the protolith. However, without direct evidence of hydrothermal mobilization or enrichment processes, these metals may not always be present in economically significant concentrations.
Would you like a more detailed discussion of potential tectonic settings or examples of REE- and PGE-rich mylonites?

[@rogerhanson3468]

@professionalgeologyclub
THANK you for the explanation, I have acquired a mining claim that I truly believe has not been prospected as for the hard Rock aspect, the claim is in a transition zone, granitic, with numerous quartz veining, what I found interesting was that there's a ledge of what appears to be mylonite dissecting both the claims and the composition of the host rock is variable, these are My first adventure, the material from the mylonite area is much heavier than the surrounding matric rock, I've found one small seem of quartz veining cutting across the mylonite area that shows some mineralization, but it was hidden under schist debris, needless to say I find it interesting, and I'm not that good as identification, so I really do appreciate you reaching out to me with your advice on the issue, I'll be sure to Investigate the area a bit more, what I forgot to mention is that a mountain pass actually almost starts on the north corner of the claim, I'm guessing that it's a indicates a fault zone.