Structures and Deformed Primary Structures
The Monash Site for Structural Geology Photos
Section index
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Ptygmatic folds Mylonitic Granite Dykes Graded Bedding Folded Cross-Bedding in High-Grade Rocks
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Leucosomes
Sheared Pegmatite Pseudotachylyte Melt-lubricated thrusts: an evolution |
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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.
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
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Ptygmatic folding, Broken Hill |
Ptygmatic folding, Broken Hill. Cookie for scale. |
Ptygmatic folding, Broken Hill. |
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| 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
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| 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. |
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| 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
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| 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
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| 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
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| 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
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| Sheared Pegmatite. Dextral deformation of K-feldspar grains in pegmatite margin in the Eldee Creek, Broken Hill Block. |
Same shear zone in pegmatite. |
Pseudotachylyte
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| Pseudotachylyte from the detachment fault zone in Stellida, Naxos, Greece. |
Melt-lubricated
thrusts: an evolution
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| 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. |
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| A tight fold riding on a narrow leucosome detached from the foliated rock below. |
