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El Pichao Ultramylonites, Argentina
2004-2011 by Roberto Weinberg. All rights reserved. Unlimited
copy or use is hereby granted for non-profit driven enterprise, subject
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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.
|Figure 1A: Granitic protolith with xenoliths of Punco-Viscana source rocks.||Figure 1B: Wall showing strain gradation from ultramylonites to mylonites marked by an increase in the number of porphyroclasts. Notice also large clasts derived from pegmatites.|
|Figure 1C: Detail of variations in modal content of porphyroclasts.|
|Figure 1D: Gradation into ultramylonite in block.||Figure 1E: Detail of breakdown of pegmatite into ultramylonite zone.|
|Figure 1F: Ultramylonite: granitic protolith intruded by pegmatite. Foliation dips 45 degrees into the photographed surface. Down plunge of the stretching lineation.||Figure 1G: Detail of 1A. Rotation of the large pegmatite clasts caused considerable circumcentric strain marked by stretched feldspar clasts.|
|Figure 1H: Detail of 1F. Notice tourmaline-bearing clasts of pegmatite. Interesting contrast between comet-shaped K-feldspar and other clasts with no tails.||Figure 1I: Detail of 1F.|
|Figure 1J. Same surface as Fig. 1F. Foliation dips 45 degrees into the photographed surface. Down plunge of the stretching lineation.||Figure 1K. Detail of 1J showing rotation of the large K-feldspar.|
|Figure 1L.Detail of 1J. Mantled K-feldspar clasts perpendicular to the stretching lineation.|
|Figure 2A. Naked garnet and K-feldspars in ultramylonite.||Figure 2B. Naked garnet and K-feldspars in ultramylonite.|
|Figure 3A. Thrusting: asymmetric stretching of Tml-pegmatite in mylonite, parallel to lineation, Arbolar.||Figure 3B. Thrusting: asymmetric stretching and a naked clast of Tml-pegmatite in ultramylonite, parallel to lineation, and very cloase to Fig. 3C, Arbolar.|
|Figure 3C. Thrusting: , parallel to lineation, Arbolar.||Figure 3D. Thrusting: , parallel to lineation, and very cloase to Fig. 3C, Arbolar.|
|Figure 3E. Same as 3C showing variation in modal amount of clasts. Parallel to lineation, Arbolar.||Figure 3F. Thrusting: complex and sigma clasts of K-feldspar, parallel to lineation, Arbolar.|
|Figure 3G. Thrusting: asymmetric stretching of Tml-pegmatite in mylonite, parallel to lineation, Arbolar.||Figure 3H. Thrusting: delta Tml-pegmatite clasts, and much smallel K-feldspar sigma clast, parallel to lineation, Arbolar.|
|Figure 3I. Folded ultramylonite block, scale: 2m in horizontal Anchillo.|
|Figure 4. Pseudotachylite.|