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Structures and Deformed Primary Structures

The Monash Site for Structural Geology Photos

Roberto Weinberg

 

 

Copyright 2004-2011 by Roberto Weinberg. All rights reserved. Unlimited permission to copy or use is hereby granted for non-profit driven enterprise, subject to inclusion of this copyright notice and acknowledgment of the source URL: users.monash.edu.au/~weinberg.

 

I would very much appreciate an email stating how this material will be used: Roberto Weinberg, Monash University, Australia. Thanks, RW.

 

DISCLAIMER. The material on this website has not undergone the scrutiny of Monash University and does not conform to its corporate web design. It is entirely based on a free-spritied, curiosity-driven research effort by the author, and therefore in no way expresses the official position of the University.

 

Section index

 

 

Ptygmatic folds

 

Mylonitic Granite Dykes

 

Graded Bedding

 

Folded Cross-Bedding in High-Grade Rocks

 

Leucosomes

 

Sheared Pegmatite

 

Pseudotachylyte

 

Melt-lubricated thrusts: an evolution

 

Copyright 2004-2009 by Roberto Weinberg. All rights reserved. Unlimited permission to copy or use is hereby granted for non-profit driven enterprise subject to inclusion of this copyright notice and my World Wide Web URL: http://users.monash.edu.au/~weinberg. I would very much appreciate an email stating how this material will be used. Thanks, RW.
DISCLAIMER. The material in this website has not undegone the scrutiny of Monash University and does not conform to its corporate outlook. It is entirely based on a free-spritied, curiosity-driven research effort by the author, and therefore in no way expresses the official position of the University.

 

Ptygmatic folds

 

Ptygmatic folding, Broken Hill

Ptygmatic folding, Broken Hill. Cookie for scale.

Ptygmatic folding, Broken Hill.



Ptygmatic folding, seen in 3D. hinges plunge steeply. Broken Hill. Ptygmatic folding.Broken Hill. Note change to boudinage parallel to regional foliation. Half a cookie for scale.

 

 


 

Mylonitic Granite Dykes

 

Mylonitic granite dykes randomly folded, outcrop on Adelaide road, 13 km from Broken Hill. Mylonitic granite randomly folded, outcrop on Adelaide road, 13 km from Broken Hill.

Mylonitic granite randomly folded, outcrop on Adelaide road, 13 km from Broken Hill. Mylonitic granite randomly folded, outcrop on Adelaide road, 13 km from Broken Hill.

 

 


 

Graded Bedding

 

Inverted graded bedding: from sandstone at the base (just above the finger) through to mudstone at the top, now a coarse biotite-sillimanite schist. Notice the refraction of the foliation indicating that the schist is more competent than the sandstone. Same. Same, note sharp transition from the coarse schist below to sandstone above.

 

 


 

Folded Cross-Bedding in High-Grade Rocks

 

Folded cross-bedding. Note the truncation of folded layers below by the beds above (just below the coin). preserved in concretions within sedimentary rocks that underwent high-grade metamorphism during the 1600M Olarian Orogen. Two sets of truncated cross-beds, later folded marked by * . Preserved in concretions within sedimentary rocks that underwent high-grade metamorphism during the 1600M Olarian Orogen. Channel in psammite, preserved in concretions within sedimentary rocks that underwent high-grade metamorphism during the 1600M Olarian Orogen

 

 


 

Leucosomes

 

 

 

Axial planar leucosome. Twanging locality in Purnamoota road, outside Broken Hill. Late, steep, D3 leucosome bending earlier D2 leucosome. Conjugate set of leucosomes in shear bands. Note the strong axial planar foliation in the paleosome, bisecting the angle defined by the two sets. Broken Hill. Axial planar leucosome. Close to the previous locality, leucosomes are found in the axial plane.

 

 


 

Sheared Pegmatite

 

Sheared Pegmatite. Dextral deformation of K-feldspar grains in pegmatite margin in the Eldee Creek, Broken Hill Block.

 

Same shear zone in pegmatite.

 

 


 

Pseudotachylyte

 

Pseudotachylyte from the detachment fault zone in Stellida, Naxos, Greece.

 

 


 

Melt-lubricated thrusts: an evolution

 

Early stages. Tml-leucosome segregation in an incipient fold. A more developed stage, diffuse segregation of leucosome into thrust plane. Tighter fold with a better developed segregation.

A tight fold riding on a narrow leucosome detached from the foliated rock below.