ORIGINAL PAPER
Chemical characteristics (REE, etc.) of Paleozoic and Mesozoic
graywackes and sandstones from Central Europe
Karl Hans Wedepohl • Klaus Simon
Received: 20 April 2012 / Accepted: 12 May 2012 / Published online: 30 May 2012
 The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract During the Variscan orogeny in Central Eur-
ope, partial melting in the lower continental crust formed
granitic magmas, which intruded into the upper crust and
left compounds of Ca (plus Eu2?), Mg, etc. in the lower
crust. From the late Paleozoic decomposition of the tona-
litic upper crust, sedimentary graywackes were produced
reflecting the composition of this crust. The repeated
reworking of the sedimentary cover caused the formation
of sands. Sandstones as their products of consolidation
contain increasing fractions of quartz and decreasing
feldspar from Carboniferous and Triassic to Cretaceous
age. A distinct negative Eu anomaly characterizes the
majority of these rocks. The latter is imprinted by the
Variscan magmatism. Quartz as used for numerous Medi-
eval wood ash glasses is marked for its Central European
origin by a distinct negative Eu anomaly in contrast to
many soda glasses produced outside Germany mostly with
a small or none Eu anomaly.
Keywords Graywackes  Sandstones  Quartz  Rare
earth elements  Medieval glass
We have investigated quartz-bearing coarse-grained sedi-
mentary rocks as originally being formed from tectonic and
weathering detritus of the Variscan orogenic mountains in
Germany. This orogeny occurred from about 380 to
240 Ma ago and was triggered by heat from the upper
mantle. The heat caused partial melting in the lower
continental crust and formed granitic partial melts, which
intruded into the upper crust. This orogenic magmatism is
connected with an accumulation of potassium and sodium
in the granitic melts of the upper crust and of calcium and
magnesium in the melting residues of the lower crust.
Sandstones formed after the Variscan orogeny contain
minor magmatic detritus. The systematic change of their
chemical composition with decreasing age will be inves-
tigated in this study.
We will use the composition of the 40 km thick conti-
nental Earth’s crust as a reference to explain the composi-
tion of Paleozoic and Mesozoic coarse-grained sedimentary
rocks. A standard profile of the continental crust as taken
from a 3,000-km long part of the 4,800-km long traverse of
reflection seismic surveys through Europe from the North
Cape to Tunesia informs us about the abundance of crustal
rocks (Ansorge et al. 1992). This standard profile consists of
7.6 % sedimentary cover, 45 % granites, gabbros, gneisses,
mica schists and amphibolites plus 47.7 % lower crustal
felsic and mafic granulites. Details about the compositions
of the crustal units and concentrations of the chemical
elements in the bulk crust were reported by Wedepohl
(1995). This bulk crust composition is listed in Table 1. It is
close to the composition of tonalites and quartz diorites as
common intrusive magmatic rocks.
The abundance of rare earth elements (REE) in our
samples will be used as indicators of certain rock forming
processes. They were analyzed by Laser Ablation Induc-
tively Coupled Plasma Mass Spectrometry. Under normal
conditions in the continental crust, the REE (La, Ce, Pr,
Nd, Sm to Lu) are trivalent. Exceptions are related to
certain oxidizing or reducing conditions in the crust. Oxi-
dizing conditions occur in deep-sea sediments with the
formation of manganese oxide concretions (MnO2). Here,
Ce4? can be formed and be precipitated in MnO2 (Toyoda
Communicated by J. Hoefs.
K. H. Wedepohl  K. Simon (&)
Go¨ttingen, Germany
e-mail: ksimon@gwdg.de
123
Contrib Mineral Petrol (2012) 164:693–696
DOI 10.1007/s00410-012-0768-y
et al. 1990). In seawater being residual from this precipi-
tation, a negative Ce anomaly will be detected indicating
the process of Ce4? accumulation under oxidizing
conditions.
In a former paragraph, we have mentioned the magmatic
accumulation of K and Na in the upper crust and of Ca and
Mg in the lower crust. Reducing crustal conditions cause a
precipitation of Eu2? in Ca-rich minerals as plagioclase,
etc., in the lower crust, resulting in a positive Eu anomaly
in the REE series. The positive anomaly of the lower crust
is compensated by a negative anomaly in the upper crust.
The negative Eu anomaly can be observed in the REE
spectra of abundant sandstones in Fig. 1.
We have started our present investigation with chemical
analyses of a composite of 17 graywackes, which are
sandstones containing a large proportion of detrital rock
fragments, feldspars, quartz, mica, etc. The samples came
from the following areas: Eifel (3), Rhein-Mosel (3),
Hessia (4), Westphalia (2), Harz Mountains (4) and Silesia
(1). The majority of the sampled graywackes is of Car-
boniferous and the minority of Devonian age.
In Table 1, we have listed the major element averages of
the continental earth’s crust (Wedepohl 1995) and of the
mentioned composite of 17 graywackes. Because of
important similarities in chemical composition between the
graywackes (B) and the continental crust (A), the ratios B/A
are close to one for the majority of elements. Exceptions
with ratios B/A close to 0.5 are the elements Ca and Mg
because they are accumulated in the lower continental crust
in plagioclase, etc., as residues of partial melting. The
majority of the sampled graywackes with their chemical
similarity to abundant crustal rocks indicates their origin
from materials formed by the Variscan orogeny. Because
the abundance of the REE is similar in graywackes and in
the continental crust, the crust-normalized concentrations of
La, Pr, Nd, Sm, Tb, Dy, Er, Tm and Yb in Fig. 1 are close to
one. They are actually close to 1.3. We observe a negative
Ce anomaly indicating seawater environment, and a posi-
tive Eu anomaly in the lower crust from residues of partial
melting related to a negative anomaly in the upper crust.
Sandstones of Carboniferous, Triassic and Cretaceous
age also have like the graywackes distinct Eu anomalies in
memory of the Variscan partial melting events (Fig. 1). We
have analyzed composites of 12 Carboniferous, 23 Triassic
and 11 Cretaceous sandstones by X-ray fluorescence. The
majorities of the Carboniferous samples came from West-
phalia, those of Triassic rocks from Hessia, and those of
Cretaceous materials from Lower Saxony. Table 2 presents
the major element concentrations in composites of gray-
wackes and sandstones. In the sequence from older to
younger rocks (except Triassic sandstones), SiO2 increases
remarkably. This increase is compensated by a decrease in
Al2O3, Fe2O3, MgO, CaO, Na2O and K2O (again with
exceptions in Triassic sandstones). Aluminum concentra-
tions are mainly incorporated in feldspar (and mica). These
minerals decrease with distance from the orogeny and the
sources of graywackes. The negative Ce and Eu anomalies
in sandstones plotted in Fig. 1 confirm the fact that all these
sediments were deposited under seawater and that their
original material came at-least partly from the Variscan
orogeny. The sequence from older to younger sandstones
demonstrates how the original material was repeatedly
reworked by weathering, erosion and deposition.
One of the applications of our present investigation is
the search for specific properties of quartz used for Medi-
eval glasses in Germany. The 23 investigated wood ash
Table 1 Average concentrations of major elements in the Conti-
nental Earth’s Crust (A), and in a composite of 17 Paleozoic gray-
wackes from Germany (B)
A B C
Continental crust 17 Graywackes Germany B/A
SiO2 (%) 61.5 67.21 1.09
TiO2 0.68 0.68 1.00
Al2O3 15.1 11.49 0.76
Fe2O3 6.28 6.7 1.07
MnO 0.10 0.11 1.14
MgO 3.7 1.4 0.38
CaO 5.5 2.91 0.53
Na2O 3.2 1.9 0.60
K2O 2.4 1.8 0.75
P2O5 0.18 0.14 0.78
CO2 0.73 2.4
H2O 3.13
R 99.4 99.9
Third column: the ratio B/A
greywacke composite (17)
Carboniferous sandstones (11)
Triassic sandstones (23)
Cretaceous sandstones (12)
wood ash glass (23)Co
nt
in
en
ta
l C
ru
st
 n
or
m
al
ize
d 
co
nc
en
tra
tio
ns
 o
f
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
R
EE
 in
 ro
ck
s 
an
d 
gl
as
se
s
0.1
0.5
1.0
1.5
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Fig. 1 REE concentrations in rocks normalized to REE concentra-
tions in the Continental Earth’s Crust. Rocks are 17 Paleozoic
graywackes, 11 Carboniferous sandstones, 23 Triassic sandstones, 12
Cretaceous sandstones and 23 wood ash glasses from Germany
694 Contrib Mineral Petrol (2012) 164:693–696
123
glasses came from Hoexter (Westphalia), Mainz, Laud-
engrund (Spessart), Brunshausen (Gandersheim) and
Lorsch (Wedepohl et al. 2011). They were made from
quartz plus wood ash between the eighth and the fifteenth
century in processes specific for that time and area. The
major element composition of the 23 Medieval wood ash
glasses is listed in Table 2 and their crust-normalized REE
composition in Fig. 1. These wood ash glasses contain
distinctly less SiO2 but much more CaO and K2O than the
sandstones. Besides those 23 materials listed in Table 2,
we have observed wood ash glass with an Eu anomaly at
Steimcke and Drudewenshusen (both near Go¨ttingen),
Paderborn and Sady (CR). Quartz for the glass production
is commonly gained from river and sea beds or Tertiary
deposits with local accumulation of this mineral. The latter
sources apparently contain quartz with similar REE pat-
terns as the sandstones and graywackes from Central
Europe including Eu and Ce anomalies (Fig. 1). This
means that the decomposition of sandstones caused the
formation of quartz accumulations. The impact of the
Variscan orogeny has finally marked rather large volumes
of rocks. The average crust-normalized REE concentra-
tions of the wood ash glasses in Fig. 1 are very similar
(except the Eu anomaly). But the size of these concentra-
tions is only a third of that of the continental crust (Wed-
epohl et al. 2011, Table 2).
In antiquity and the medieval period, two additional
glass types beside wood ash glass were in general use in
Europe and the Near East, etc.: soda lime glass and soda
ash glass. In Fig. 2, we have plotted the average continental
crust-normalized REE concentrations in 23 wood ash
glasses, 16 soda lime glasses and 20 soda ash glasses as
reported by Wedepohl et al. (2011). In this figure, an
almost general existence of distinct Eu anomalies is
restricted to the type of wood ash glass. Only two of the
wood ash glasses have not such an Eu anomaly. These are
from the Spessart Mountains. Six of the investigated
Roman soda lime glasses from the production of Hambach
west of Cologne (Gaitzsch et al. 2000) have a weak or
minor negative and two have a positive Eu anomaly. Two
of these soda lime glasses from Bonn, two from Gellep,
two from Hambach and one from Augst have no anomaly
at all. The third common glass type is soda ash glass that
was produced in the period from 900 to 1250 AC exclu-
sively in Islamic areas. Eight samples of beakers with
Table 2 Average
concentrations of major
elements by RFA in composites
of 17 Paleozoic graywackes, 12
Carboniferous sandstones, 23
Triassic sandstones and 11
Cretaceous sandstones from
Germany, and average
concentrations of major
elements by microprobe in 23
Medieval wood ash glasses
from Germany (Wedepohl et al.
2011)
17 Graywackes
Germany
11 Carboniferous
sandstones
23 Triassic
sandstones
12 Cretaceous
sandstones
23 Wood ash
glasses (Medieval)
Germany
SiO2 (%) 67.21 80.56 80.1 91.24 50.2
TiO2 0.68 0.33 0.34 0.13 0.15
Al2O3 11.49 8.02 7.5 1.64 2.11
Fe2O3 6.7 4.6 2.52 3.61 0.73
MnO 0.11 0.08 0.03 0.03 1.09
MgO 1.4 0.57 0.55 0.02 4.35
CaO 2.91 0.21 0.76 0.05 22.6
Na2O 1.9 0.8 0.5 0.01 0.89
K2O 1.8 1.9 3.7 0.4 13.0
P2O5 0.14 0.07 0.1 0.03 4.04
CO2 2.4 1.34 1.3 1.5
H2O 3.13 1.78 2.53 0.79
R 99.9 98.5 97.4 98.7 99.2
Quartz (%) 57 66 72
Feldspar (%) 13 25 5
wood ash glass (N=23) 
soda lime glass (N=16) 
soda ash glass (N=20) 
Ab
un
da
nc
e 
in
 g
la
ss
 / 
Ab
un
da
nc
e 
in
 th
e 
Co
nt
in
en
ta
l
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Ea
rth
's 
Cr
us
t
0.20
0.25
0.30
0.35
0.40
0.45
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Fig. 2 Average REE concentrations of 23 wood ash glasses, 20 soda
ash glasses and 16 soda lime glasses normalized to REE concentra-
tions in the Continental Earth’s Crust
Contrib Mineral Petrol (2012) 164:693–696 695
123
enamel paintings from Venice (excavated at Hoexter) plus
three Islamic vessels sampled at Brno (CR) plus four
Hedwig beakers with carved decorations (sampled in more
than 18 localities in Europe) plus three colored glasses
from Qantir in Egypt represent this glass type in our
investigation. Only five of the eight beakers from Venice
have minor negative Eu anomalies. Two of the three Isla-
mic vessels from Brno also have minor negative Eu
anomalies. The third glass from this locality has a distinct
negative Eu signature. Of the 20 representatives of the soda
ash type, the four Hedwig beakers exclusively have a dis-
tinct negative Eu anomaly. Conclusions from their chem-
ical investigation locate their production, which is dated to
a few decades after 1200 AC, in the area of the Levant at
the Mediterranean Sea (Wedepohl 2005).
The first part of this publication is restricted to quartz
used for wood ash glass in Germany, which is combined
with a distinct negative Eu anomaly introduced through
Late Paleozoic magmatism in the upper crust. Considering
a much larger geographic area of glass production by the
inclusion of soda ash and soda lime glass outside Germany,
the negative Eu anomalies decrease to a minor size. The
latter case seems to be normal for the upper crust in
general.
Conclusions
The repeated reworking of coarse-grained quartz-bearing
materials from Variscan rocks and their deposition in the
Carboniferous to Cretaceous sea formed sands and sand-
stones with increasing proportions of quartz. The youngest
deposits still reflect imprints of the Variscan orogeny as an
Eu anomaly. Wood ash glass produced in Medieval Ger-
many carries distinct negative Eu anomalies from the same
source as in sandstones. Soda glass from large areas outside
Germany has only small or none positive or negative Eu
signatures.
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