Carbonatite

Carbonatite intrusions occur towards the end of the evolution in the center of the Kaiserstuhl complex. They are accompanied by the formation of ultramafic breccias which fill pipe structures at the subvolcanic level. Small alvikitic dikes are the final magmatic intrusions in the center of the complex. Carbonatites occur in three types of geological setting and petrographic appearance:

1. Subvolcanic intrusion in the center of the Kaiserstuhl complex. They are middle to coarse grained sövites. Their outcrop area is about 1 km².
2. Alvikitic dyke, generally less than 1 m, often only 1-2 cm thick. Some of these dikes have porphyritic textures.
3. Extrusive carbonatites with droplet-shaped lapilli (Pele's tears).

Calcite, magnetite and apatite are the essential mineral in the carbonatites. Carbonates are almost exclusively calcitic, only a few late-stage veins with ankeritic dolomite have been described. Small amounts of the following accessories may be present: forsterite, diopsidic augite, melanite, Nb-perovskite, pyrochlore, baryte, pyrite and rarely zirconolite, baddeleyite, zircon. Several micas are known: phlogopite, and Ba-phlogopite.

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Schelingen carbonatites outcrop. From La lithothèque

Schelingen sövite. From La lithothèque

Volcanic calcite-carbonatite (alvikite). Badberg. From Sand Atlas

Bibliography

• Ulianov, A., Müntener, O., Ulmer, P., & Pettke, T. (2007). Entrained macrocryst minerals as a key to the source region of olivine nephelinites: Humberg, Kaiserstuhl, Germany. Journal of Petrology, 48(6), 1079-1118.
• Walter, B. F., Marks, M. A. W., & Markl, G. (2016). The Kaiserstuhl natural laboratory-an introduction and first results. Abstract Malawi Expert Council.
• Weisenberger, T. B., Spürgin, S., & Lahaye, Y. (2014). Hydrothermal alteration and zeolitization of the Fohberg phonolite, Kaiserstuhl Volcanic Complex, Germany. International Journal of Earth Sciences, 103(8), 2273-2300.
• Weisenberger, T., & Spuergin, S. (2009). Zeolites in alkaline rocks of the Kaiserstuhl Volcanic Complex, SW Germany–new microprobe investigation and the relationship of zeolite mineralogy to the host rock. Geologica Belgica

Photo
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)	Oriented calcite crystals and dark magnetite crystals. Schelingen, Kaiserstuhl, Germany. XPL image, 2x (Field of view = 7mm)
Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 2x (Field of view = 7mm)	Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)
Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)	Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)	Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)
Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)	Calcite crystals, dark magnetite crystals and brown Koppite crystals. Schelingen, Kaiserstuhl, Germany. PPL image, 10x (Field of view = 2mm)