Kaiserstuhl Excursion
Geological map Kaiserstuhl

Outrcrop description based on Keller (1984)

1. Quarry Hauri 
wollastonite bearing phonolite, Fohberg/Bötzingen-Oberschaffhausen
R: 3403500    H: 5327400
Phonolitic intrusion body 600 x 400 meter in diameter in the last active quarry in the Kaiserstuhl volcanic complex, own by the family Hauri. The phonolit intruded into the Pechelbronner unite of Oligocene age.
The Intrusion is characterized by a wollastonite (CaSiO3) content, whereas wollastonite crystallized during magmatic fractionation. These theory is supported be the bulk rock chemistry with a high CaO content at high alkalinity, which express by an agpaitic index of 0.9. Xenolith of gneissic and granitic origin, showing metasomatic fenitisation occur beside xenolith of sedimentary units. Sporadical essexitic dikes crosscut the intrusive body.
The primary phonolitic mineralogy is highly hydrothermal altered, whereas nepheline is altered to natrolite (zeolite). Zeolites and other secondary minerals, like calcite and apophyllite are found on fissure, which are interested for mineral collectors.
In former time quarrying was done for gravel production. Due to the chemical behaviour of natrolite as good cation exchanger, the phonolite powder is used in the concrete industry, in medicinial products, glass industry, agriculture, forestry and environment (e.g. flue gas detoxification).

SiO2 49,28 sanidine  31,7 vol. %
TiO2 0,34 natrolite 45,0 vol. %
Al2O3 17,92 wollastonite 10,0 vol. %
Fe2O3 2,44 calcite 1,1 vol. %
FeO 1,43 augite 9,3 vol. %
MnO 0,28 melanite  1,0 vol. %
MgO 0,66 apatite, titanite 0,5 vol. %
CaO 7,32 magnetite 0,5 vol. %
Na2O 6,81 goetzenite 1,1 vol. %
K2O 0,86
P2O5 0,14
CO2 2,01
H2O 4,68
total 98,47
chemistry and modal mineral conent of the Fohberg phonolite (ALBRECHT1981)

quarry Hauri,  Bötzingen (view from Vogelsangpass)

quarry Hauri

essexitic dike crosscut the phonolitic intrusion

2. Soevite, carbonatite,  Orberg/Schelingen
Bruch V:   R: 3402650    H: 5330490
Bruch III:  R: 3402580    H: 5330380
The Orberg quarry V point out an igneous layering of the coarse grained carbonatite, which is defined as soevite. Coarse grained calcite crystals up to 30 cm are found. Quarry II which stretch from the district road up to quarry V point out the dike nature of the carbonatitic intrusion, associate with highly greenish altered diatremic breccias. Calcite is by fare the frequent mineral content up to 90 volume per cent of the carbonatite. Addionally magnite, appatite, Mg-rich forsterite, phlogophite and cherry-red koppite (pyhrochlor) occur.

1 2 3
SiO2 1,37 1,69 1,27
TiO2 0,05 0,09 0,16
Al2O3 0,35 0,48 0,54
Fe2O3 3,18 3,03 2,24
MnO 0,42 0,69 0,32
MgO 3,05 0,73 0,58
CaO 48,60 49,00 52,36
Na2O 0,10 0,08 0,10
K2O 0,03 0,09 0,05
P2O5 2,87 1,74 1,47
CO2 37,20 38,40 27,20
H2O -- -- 1,85
total 37,20 96,02 98,36
chemcial analysis of crabonatite
1 soevite, Orberg Schelingen (KELLER 1984)
2 average of 52 alvikitic dikes (KATZ & KELLER 1981)
3  carbonatitic lapilli stone, Henkenberg (KERLLER 1981)

carbonatite thin section, image width: 3,7 mm

quarry V Orberg, Schelingen


3. Phonolitic intrusion, Kirchberg/Niederrotweil
R: 3396700    H: 5528100
Sodalite bearing phonolite intrusion  in the old Kirchberg quarry. The contact to the country rock is exposed in the SE corner of the quarry, whereas the temporal position of the intrusion is visible. The country rocks exists of tephritic agglomerates. The quarry is famous for findings of melanite, apophyllite, fluorite, calcite and natrolite. But respect the closure of the quarry during the first half of the year, because of nature protection.

SiO2 55,79 K-feldspar 61,0  vol. %
TiO2 0,31 plagioclase 2,0 vol. %
Al2O3 19,45 sodalite-hauyn 28,0 vol. %
Fe2O3 2,77 augite 3,5 vol. %
FeO 0,67 melanite 1,5 vol. %
MnO 0,23 ore 2,0 vol. %
MgO 1,63 calcite 1,5 vol. %
CaO 2,13 apatite, tinatite 0,5 vol. %
Na2O 7,94
K2O 5,44
P2O5 0,06
H2O 1,16
CO2 0,22
SO3 0,94
total 98,74
chemcial composition of the Kirchberg phonolite (WIMMENAUER 1962)

phonolite, Kircherg quarry

exctrusive carbonatite
4. Henkenberg/Niederrotweil
R: 3396350    H: 5329380
5. Kirchberg/ Niederrotweil
R: 3396850     H: 5328000
Extrusive carbonatite occur only at two places in the Kaiserstuhl volcanic complex: Henkenberg and Kirchberg. In both cases the carbonatitic lapillistone consists round to tear-shape lapillis. Tace element characterisation of the chemical composition reflects alvicitic affiliation with a trachytoidal structure. The localities provides as world wide standart for extrusive carbonatite products.
The Henkenberg outcrop is nearly vanished, whereas only few field stones can be find. In contrast the Kirchberg outcrop exhibit nice outcrop conditions de to the recent vineyard consolidation.
Tace element characterisation of the chemical composition reflects alvicitic affiliation with a trachytoidal structure. The localities provides as world wide standart for extrusive carbonatite products. The lapilli stone consists mainly on calcite, with minor amounts of apatite and magnetite with accessoric augit, melanite, Nb- perovskite and pyrochlor
The Henkenberg Lapilli stone overlays the Henkenberg tuff breccia, witch contains soevitic xenoliths.

carbonatitic lapilli stone

outcrop "Blutten Bückele", Kirchberg/Niederrotweil
carbonatitic lapilli stone overlays phonolitic tuff  (17,2 ±0,1 Ma)

6. Humberg, Sponeck, between Burkheim and Jechtingen
R: 3394900    H: 5331300
7. Büchsenberg near Achkarren
R: 3396270    H: 5326880
Tephrites and the porhphyric subvolcanic equivalent essexites mark the most abundant rock type in the Kaiserstuhl volcanic complex. The best outcrops conditions are along the western flanks of the Kaiserstuhl, whereas the Humber-Sponeck complex as well as the Büchsenberg are nice localities. Both are leucite- beraing tephrites formed by parasitic volcanos on the flank of the Kaiserstuhl volcanic complex, consisting of alternating lava flows, agglomerates formed by strombolian eruption type activity and sills.
The Sponeck ruin is build on a shallow, neat surface essexite intrusion, whereas a grain size increase with depth can be seen.
The petrographic composition varies in a small range with Ti-augite as characteristic dominating phase (25-35 vol. %). Olivine can be found in a few samples. Plagioclase do not present a liquidus phase and appear only in a few sample as phenocryst generation.
Leucite marks the most frequent feldspathoid, however it is fully replace by analcime. Nepheline tephrites accure rarely and sometimes soldaite, K-feldspar, biotite and amphibole are found. Classification by using the QAPF diagram (Streckeisen diagram) results in phonolitic tephrites. Mg-numbers cumulate between 50 and 55, which illustrates a medium fractionation degree. Age dating have shown that tephrites were erupted during the whole magmatic activity of the Kaiserstuhl complex.

1 2 3
SiO2 45,44 43,34 46,76
TiO2 2,88 2,64 1,58
Al2O3 14,15 15,72 17,63
Fe2O3 7,24 5,42 8,63
FeO 4,71 5,79 4,45
MnO 0,16 -- --
MgO 5,11 5,49 3,68
CaO  12,88 12,49 10,52
Na2O 1,98 3,29 2,70
K2O 3,23 2,24 1,68
CO2 -- 0,14 0,40
P2O5 0,54 0,27 0,29
H2 1,84 2,70 2,37
Cl 0,13 0,12 --
total 99,69 99,74 100,60

quarry Büchsenberg nearAchkarren,alternating tephritic lava flows and pyroclastic units

tephritic agglomerate, Schloßberg/Achkarren
chemical analysis:
1 leucitetephrite, Bitzenberg near Bickensohl
2 leucite-free tephrite, Eichert
3 essexite, Sotenkopf (SOELLNER 1928)

8. Olivine-nephelinite Lützelberg/Sasbach
R: 3396630    H: 5334900
The outcrop “Bierkeller” at the northern flank of the Lützelberg, you can stop at an layby apprixomatelly 500 meter west on the old district road from Sasbach to the Rhine river
2 to 3 olivine-nephelinite lava flows build up the Lützelberg mountain, which are devided by agglomerates of the same chemical composition, which are associated with a scoria cone that is exposed in the Limberg quarry VII. The Bierkeller outcrop expose a multiplicity of head-size spheres, up to 25 cm in diameter. Theses spheres are mantel xenolith. The outcrops mark the riches mantel xenolith locality in the Teritary volcanic province in Soutwestern Germany. The Xenolith contains strongly altered olivine, Cr- spinel, orthopyroxene and clinopyroxene. Additionally Al-rich clinopyroxene megacrysts are found. Clinopyroxene thermbarometry data yields a source depth of around 100 km.
The olivine-nephelinite as host rocks, are characterized by high values of Ni, Cr and a high Mg number, which markets the most primitive volcanic products in the Kaiserstuhl volcanic. These indicate a fast ascent of the magma.
Age dating of the The olivine-nephelinite lava flows yields ages of 16.2 million years.


locality"Bierkeller", Lützelberg

9. Limberg/Sasbach
quarry I:        R: 3396100    H: 5335680
quarry VII:    R: 3396300    H: 5335200
Limberg quarry I expose 2 lava flows (λ1 and λ2), each up to 20 meter in thickness. Theses lava flows are divided a tuff layer t1, a significant marker for the Limberg-Lützelberg complex stratigraphy that contains phonolitic components fragments of olivine-nephelinite and xenolith of lherzolith.
The lower lava flow λ1 shows characteristic pahoehoe structures of low viscosity flow conditions.  The upper limburgite lava flow λ2 in contrast is characterized by Aa-lava type formation. The breccias appearance is cause by abrupt evaporation of water und thereby the huge volume increase during that process.
Partially the tuff layer is injected along vertical structures into the upper lava flow, which is also cause by the rapid evaporation.
Both lava flows are defined as limburgites. This term is introduced by Rosenbusch and defined as volcanic rocks with a vitreous matrix and mafic phenocrysts. Phenycrsyts thereby are olivine, magnetite and Ti-augite.
Geochemically the limburgites are of basanitic composition and display beside the olivine-nephelinites from Lützelberg the most primitive volcanic products.
The vitreous matrix often shows palagonitization , whereas elements leached during that process re-precipitates as secondary minerals, like various zeolites (faujasit, offretite,  phillipsite, ...) and carbonates.
A volcanotectonic cross-section is exposed in the Limberg quarry VII. The Limberg Graben strikes in NW-SE direction. The graben shoulders are formed by red olivine-nephelinite agglomerates and the NE graben fault is easily visible. The red wall marks the fault plane. The large volcanic bomb sizes suggest that the former vent is in near distance. The composition of the agglomerates are equeal to he olivine-nephenlinites suggesting that Lützelberg lavas were erupted on the SE site of the Limberg. The inner graben part is build up the Limburgite lava units
λ2 and yellow-brownish limnic sediments of Miocene age (Burdigal), which can be dated with fossils. This sediment are overlain by the Limburgite lava flow unit λ3.

1 2
SiO2 41,66 41,47 Ti-augit 31,5 vol. %
TiO2 3,33 2,84 olivine 10 vol. %
Al2O3 11,45 11,91 magnetite 5 vol. %
Fe2O3 5,16 10,99 groundmass 53,5 vol. %
FeO 6,72 4,04
MnO 0,15 --
MgO 11,55 6,56
CaO 12,23 13,87
Na2O 2,50 3,97
K2O 1,20 1,58
P2O5 0,70 0,57
CO2 0,75 0,75
H2O 2,30 1,95
Sum  99,70 99,69
chemcial analysis
1 limburgite λ1 (KELLER 1990)
2 limburgite
λ2 (MEIGN & STECHER,1930)
3 average limburgite L(WIMMENAUER 1959)

faujasite found in quarry I

Limberg quarry ViI, olivine-nephelinite agglomerate with volcanic bombs

Limberg quarry VII showing the limberg graben fault

Limberg quarry VII; olivine-nephelinite aglomerate with volcanic bombs and oxidized xenolits, containing fresh Cr- diopside

Limberg quarry 1: lava flow λ1 and λ2 are devided by tuff layer