Stylolite
Stylolites are finely linear and wavy-jagged structures in sedimentary rocks , predominantly in sedimentary carbonate rocks , which are often vein-shaped in red, purple, yellow or gray colors. They go back to pressure release processes in the rock.
term
The name for this rock feature is derived from the Greek word στυ̃λος for pillars.
Foreign language terms
english: stylolite ; French: stylolithe, stylolite ; Russian: стилолит ; Italian: stilolite ; polish: stylolit ; Portuguese: estilólito ; Romanian: Stilolite
Origin
Stylolites form in sedimentary rocks when increased load pressure (see lithostatic pressure ) leads to partial dissolution of minerals in the rock. They typically run along layer surfaces . Due to the occurrence of lateral pressure ( tectonic stress), they can also occur at interfaces that are oriented perpendicular or at an angle to the sedimentation plane. It is then difficult to distinguish them from fine fractures if they have developed less jagged shapes. However, since simple fractures and fissures are often the result of stretching processes, these often expand in their course and are then filled with secondary minerals, which is not the case with stylolites.
Manifestations
Stylolites are often found in chemically relatively pure (mono-mineral) and homogeneous rocks. Their characteristic image are sawtooth-shaped jagged veins. They mainly occur in carbonate sedimentary rocks. In rare cases, stylolites have also been observed in quartzites , sandstones and claystones (argillites).
Those with red, purple or black color are particularly noticeable to the viewer. Stylolites in gray and beige tones are less obvious. The colors mostly come from iron or manganese oxide impregnations, similar to the dendrites in sedimentary rocks. Other sedimentary rocks contain clay layers and malachite deposits along the stylolithic structures . The colored deposits are residues of minerals that did not go into solution when subjected to pressure. In some cases, calcite and quartz accompany the irregular surface of stylolithic structures.
Microstylolites can appear at the grain boundaries of oolites or bulbous rock structures. They are seen on some oolithic limestones and tuber limestones .
Another form is the bundle-like appearance of stylolites in the decimeter range in sedimentary rocks.
Technical and visual effects
They are often perceptible in ashlar as an attractive line pattern when the raw block has been sawn open perpendicular to the sedimentation plane. If, for technical reasons, the rock can only be sawed parallel to the layer plane, stylolites are marked as spotty, cloudy fine structures and have an overall color effect on the surface or speckle-like formations, which can lead to significant color fluctuations in the batches produced.
Individual evidence
- ↑ А. Н. Криштофовича: Геологический словарь, том II. Москва 1960, p. 290
- ↑ Raymond Perrier: Les Roches Ornementales. Ternay 2004, p. 301
literature
- А. Н. Криштофовича: Геологический словарь , том II. Москва 1960
- Hans Murawski: Beringer Geological Dictionary . Stuttgart 1957
- Raymond Perrier: Les roches ornementales . Ternay 2004, ISBN 2-9508992-6-9
- Johannes H. Schroeder: Natural stone in architecture and building history of Berlin . Berlin 2006, ISBN 978-3-928651-12-7
- Roland Vinx: Rock determination in the field . Munich 2005, ISBN 3-8274-1513-6