ESR-dating of a flowstone core from cova de sa Bassa Blanca: Mallorca, Spain
ENDINS, n." 12.1986. Ciutai de Mallorca
ESR-DATING OF A FLOWSTONE CORE
FROM COVA DE SA BASSA BLANCA
(Mallorca, Spain)
by Rainer GRUN *
Abstract
A flowstone core from the Cova de Sa Basa Blanca (SBB), Mallorca, was dated by
means of ESR. This systematic investigation shows that the precipitation of this flow-
stone took place in several time-periods. It began at about 700,000 a and finished at
the end of.the penultimate interglaciation at about 200,000 a.
Resumen
Una muestra de material estalagmítico parietal procedente de la Cova de Sa Bassa
Blanca (testigo n." Pl/campaña de muestre0 de marzo-81) ha sido datada mediante la
técnica de Resonancia de Spin Electrónico (E.S.R.). Las investigaciones realizadas sis-
temáticamente sobre dicha muestra han puesto de manifiesto que la precipitación de
esta secuencia de espeleotemas tuvo lugar en varios períodos de tiempo; habiendo
comenzado en torno a los 700.000 años y acabando hacia el final del penúltimo inter-
glacial, hace alrededor de 200.000 años.
A flowstone core of about 190 cm from the
Cova de Sa Bassa Blanca (SBB) was dated by
means of ESR. This core (N.O 21) was taken during
ESR-spectroscopy allows the detection of un-
a campaign in this cave (MAROTO & FONT, 1981)
paired, paramagnetic, quasi free electrons in the
i n order t o investigate the paleoclimate of the Wes-
crystal lattice. These free electrons are produced
tern Mediterranean. The Cova de Sa Bassa Blanca
b y the natural radiation (alpha-, beta-, garnma-,
is connected with the Mediterranean Sea and typi-
and cosmic rays) and can be stabilized by vario
cal cauliflower-like speleothems, which grew suba-
traps (see MARFUNIN, 1979; HENNIG & GRU
quatically (POMAR et al., 1976, 1979), document
1983; HOROWITZ, 1984). Along with continuou
paleo-sealevels (GINÉS & GINÉS, 1974; GINÉS et
natural radiation the nurnber of trapped electron
al., 1975, 1981 a & b). First U-series dating on these
is increasing and so does the E%-signal, which i
speleothems were carried by HENNIG et al. (1981).
proportional t o the population of captured el
The subaquatic speleothems show various states
trons. An ESR-age is calculated according the S
of crystallization and a so called fibrous aragonite
ple formula:
is very conspicuous (POMAR et al. 1976).
accumulated dose (AD) [kradl
Age (Ma) =
annual dose (Do) [mradka]
Dept. of Geology, McMaster University, 1280 Main
The accumulated dose (AD), a sample received
Street West, Hamilton - Ontario, Canada L8.S 4M1.
since the time of its formation is determined by
19

ESR-spectroscopy via the so called additive dose
method (Fig. 1): Homogeneous aliquots of the
sarnple are irradiated stepwise with artificial
gamma-doses, the extrapolation towards zero-
ESR-intensity allows the determination of the AD.
The annual dose (Do) results from the analysis of
the radioactive elernents (U, Th, K) of the sarnple
(internal dose rate) and its surroundings (external
dose rate). For details of the rnethod see IKEYA
(1978), HENNIG & GRUN (1983) and GRUN (1985).
Experimental
For the ESR-age determination of the SBB-
sarnples t w o ESR-signals were used: fibrous ara-
gonite showed an ESR-signal with g = 2.0021 (Fig.
2) and the calcitic sarnples displayed an ESR-signal
with g = 2.0007 (Fig. 3), which was also used for
ESR-dating in other publications (e.g. GRUN, 1985;
SIEGELE & MANGINI, 1985). The sarnples were
crushed in a rnortar and the sieve-fraction 100-400
microns was used for the ES-rneasurernent. In or-
der t o avoid interferences frorn surface defects due
t o crushing (GRUN & DECANNIERE, 1984) the sarn-
ples were etched with 0.5N CHaCOOH for 4 rninu-
tes. Both signals showed no'decrease upon sun-
Fig. 2. ESR spectra of an aragonitic speleothern ofthe SBB.
light exposure. The therrnal stability is in the range
of sorne lo6 a (at lo0 C; HENNIG & GRUN, 1983;
HENNIG et al., 1985) and, hence, this signal should
i
\\
be stable enough to date in the range up to a mi-
\\
ru.
llion years. Unfortunately, there are no detailed
\\
O
\\
annealing results available for the aragonitic ESR
\\
\\
signal with g = 2.0021, but prior prelirninan/ an-
\\
\\
nealing tests indicated, that this signal is rather sta-
0-
\\
\\
ble. The measurement conditions are given in Fig.
\\
2 & 3. The internal U-content was measured by
\\
\\
ESR signo/ la.u.1
fission-track powder preparations.
\\
09
,
For the calculation of the ESR-ages the fol-
lowing assumptions were rnade:
- the alpha-efficiency (k-factor) was assurned to
be 0.34 throughout. Measurements of 9 speleo-
S -
thern sarnples yield a value of 0.34 + 0.08. This
result is in agreement with TL-investigations
(DEBENHAM & AITKEN, 1984), where the al-
ru.
O
pha-efficiency of speleothem sarnples varied
between 0.11 and 0.6
- the U-234/U-238 ratio was assumed to be 1.2
2-
based on the alpha-spectrometric rneasurernents
done for U-series study.
- the influence of K-40 and Th-232 is negiigible.
.b
- the influence of cosmic rays is negligible.
O
Unfortunately, it was not possible to deter-
mine the external garnrna-irradiation in the core
.
Fig. 1. Determination of AD by means of additive artificial irra-
yet, because the detector of a portable gamma-
diation.
spectrorneter had a larger diameter than the holes

Depth
Age lkal
SBB
lcml
200
400
,
600
,
800
20.5-21
9655 MHz
A
-
A
- - -- - -- - - - - - - -
Zrn M.
0.5
Gpp
A
A
A
A
V
532.5279.6
A
A
A
A
. A
A
VI
a
A
A
293.5260.0
A
.-------------------------------------
*
A
VII
5171~44.3
5 - 1 - - - - - - - - - - -
--
VIII
67110258. O
.
Fig. 3. ESR spectra of a calcitic speleothern of the SBB.
.
- - - - - - - - - - - - - - - - - - - - .
- -- - - -
e
A
A
--.-----A
---..
A
of the cores. Therefore, the externa1 gamma-dose
rate was assumed to be equal to the interna1 ex-
IX
370.8224.7
cept for those samples lying between U-rich arago-
'
A

nite layers: Here, the gamma-dose was extrapo-
lated from the aragonite layers (see Tab. 1, Nr. 6,
AESR
iTh/U
/m-
+oo)
11-15, 17). Tab. 1 shows, that the fibrous aragonite
contains much more uranium (up to 7 ppm) than
sea-water (about 0.3 ppm, KAUFMAN et al. 1971).
whife, rnicrocryst. calcite
It cannot be decided here, whether this U-uptake is
lighfbrown, fibrous aragonif
syn- or postsedimentary, but U-accumulation in
whife or lighfbrown, rnacrocrysf. calcife
aragonitic corals has been attributed to a synsedi-
basernenf (rnarine lirnesf onel
mentary uptake by SWART & HUBBART (1982).
recrysf. basernenf
For the ESR-age calculation of these samples a
pores
short time U-uptake during or shortly after precipi-
tation was assumed.
sarnple
The Th-230/U-234 and Pa-231/U-235 disequili-
bria were iteratively taken into account.
Fig. 4. ESR and U-series age data of the SBB-core.
In addition to the ESR-investigations, four U-
Left: Schernatic profile.
series age determinations were carried out by the
Right: The rornan Nurnbers.(l-IX) label the age-units
Niedersachsisches Landesamt für Bodenforschung,
ing to the ECR-results, the arabic nurnbers give t
rage age with the standard deviation.
Hannover.
cm yield very high ages. This might be due to
plate-out effect of the daughter products of Rn-22
(see HENNIG & GRUN, 19831, which might in-
Tab. 1 shows the results of the ESR- and U-
crease the ADs of samples near the surface. This
series age determinations. The ESR-results can be
effect might especially occur at this site, for there is
grouped into 9 age units (see Fig. 4). The outer few
nearly no air-circulation in the cave. A similar ob-

N . O
Depth
U-Content
AD
int. Do
ext. Do
ESR-Age
U-series Age
[cm]
[ P P ~ ]
[krad]
[mrad/a]
[al
[al
1
O- 1
5350
236.0
630.3
-
374 400
2
5-6a
5474
347.5
685.5
-
506 900
3
5-6b
596
45.6
69.4
60
352 400
244 300
4
5 - 6 ~
7057
147.8
698.9
-
211 500
5
8.5-9
499 1
123.6
515.9
-
239 600
6
1 O
337
9.0
31.4
20
175 100
7
10.5
334
15.0
35.8
i o
268 800
8
14-15
338
12.6
34.4
20
231 600
9
15a
546
15.0
53.6
20
203 800
1 O
15b
417
13.4
41.6
20
217 500
11
17-18
3684
233.0
460.9
-
505 500
12
2 1
464
15.0
47.0
20
223 900
216 500
13
25
410
8.9
41.1
-
216 500
14
27-28
317
10.3
35.0
-
294 300
15
29-30
198
5.8
21.3
-
272 300
16
34-35
235
5.1
23.6
-
216 100
17
40
300
6.0
29.4
-
204 100
18
40-4 1
145
5.2
16.3
-
319 O00
19
42
338
6.6
33.1
-
199 400
326 O00
20
47
262
7.4
28.0
264 300
2 1
52
136
5.8
15.9
-
364 800
22
56-57
149
5.0
16.6
-
301 200
23
60
113
4.9
13.3
368 400
24
61d2
103
6.5
12.9
-
503 900
25
61d3
110
5.1
13.1
-
389 300
26
62
23 1
5.5
23.7
-
232 100
27
72
479
14.9
52.3
-
284 900
28
85
153
8.5
18.8
-
452 100
29
92
57
5.6
7.6
-
736 800
30
93
68
5.0
8.7
-
574 700
3 1
97-98
89
5.6
11.1
-
504 500
32
102
95
6.5
12.0
-
541 700
33
106
66
6.2
8.7
-
712 600
34
112
77
4.6
9.5
-
484 200
35
116
65
4.8
8.3
-
578 300
36
120
100
6.5
12.6
-
515 900
37
120-121
115
6.0
14.0
-
428 600
38
123h
154
5.2
17.1
-
304 100
39
126
139
5.8
16.2
-
358 O00
40
127r
360
6.1
33.8
-
180 500
4 1
127d
257
8.9
28.7
-
310 100
42
130
284
10.1
32.0
-
315 O00
43
132.5
133
7.9
16.5
-
478 800
44
133-134
123
9.3
15.8
-
588 600
45
135
121
7.2
15.0
-
480 O00
46
136
103
7.2
13.1
-
549 600
47
137rl
140
8.5
17.4
-
488 500
48
137w
116
9.1
15.0
-
606 700
49
148-149
110
10.9
14.6
-
746 600
50
154h
120
9.9
15.1
-
655 600
5 1
154r
774
24.3
84.8
-
288 300
52
154d
284
11.6
32.9
-
352 600
225 O00
53
159
344
11.6
38.3
-
302 900
54
182- 183
1330
44.2
147.6
-
299 500
Tab. 1: ESR and U-series results

servation was made during the investigation of a
German speleothem profile (GRUN, 1985).
DEBENHAM, N, C, & AITKEN, M. J. (1984): Thermolumines-
The upper 50 cm of the profile give ESR-ages
cence dating of stalagmitic calcite. Archaeornetry, 26: 155170.
GINÉS, A. & GINÉS, J. (1974): Consideraciones sobre los meca-
of about 230,000 a, which are independent of the
nismos de foeilización de la «Cova de Sa Bassa Blancan y su
U-content. The ESR-results are in a good agree-
paralelismo con formaciones marinas del Cuaternario. Bol.
ment with the U-series data and allow a classifica-
Soc. Hist Nat. Baleares, XIX: 11-28.
tion of this part of the core into the penultimate
GINÉS, A,; GINÉS, J. & POMAR, L (1981a): Phreatic Speleo-
interglaciation (stage 7 of the 6
thems in Coastal Caves of Majorca (Spain) as Indicaton of
laO deep sea record
Mediterranean Pleistocene Paleolevela 8th Int. Congr. Speleol.,
V28-238. SHACKLETON & OPDYKE, 1973). The
Bowling Green, Kentucky, 1&24.6.1981, Proc., 533-536.
next section with aii average value of 380,000
GINÉS, A.; GINÉS, J. & PONS, J. (1975): Nuevas aportaciones al
seems to represent an older interglaciation (stage
conocimiento moríológiw y cronológico de las cavernas cos-
9 and/or 11). The deeper sections imply that the
teras mallorquinas. Speleon, Monografía 1: 49-58.
growth of the speleothem began at about 700,000
GINÉS, J.; GINÉS, A. & POMAR, L. (1981bl: Morphological and
Mineralogical Features of Phreatic Speleothems occurring
a (unit VIII). Some units (IX, VI and IV) display re-
in Coastal Caves of Majorca (Spain). 8th I n t Congr. Speleol.,
crystallization processes.
Bowling Green, Kentucky, 18-24.6.1981, Pm., 529532.
GRUN, R. (1985): Beitrage zur ESR-Datierung. SondetverórX
Geol. lnst. Univ. Koln, 59: 1-157, Koln.
Discussion
GRUN, R. & DECANNIERE, P. (1984): ESR dating: Problems
encountered in the evaluation of the naturally accumulated
dose (AD) of secondary carbonates. J. Radioanal. Nud.
The four U-series results seem to show, that
Chem., Let., 85: 213-226, Budapest.
HENNIG, G. J.; GEYH, M. A. & GRÜN, R. (1985): The interlabo-
this speleothem core grew throughout during the
ratory comparison project of ESR dating - Phase II. Nucl.
last interglaciation. The ESR-investigations show,
Tracks (in press).
however, that the speleothem growth in the Cova
HENNIG, G. J.; GINÉS, A.; GINÉS, J. & POMAR, L (1981):
de Sa Bassa Blanca is more complex and began
Avance de los Resultados Obtenidos Mediante Datación
Isotópica de Algunos Espeleotemas Subacuáticos Mallor-
about 700,000 a ago. It must be mentioned, that
quines. Endins, 8: 91-93.
the average data of the age-units are based in
HENNIG, G. J. & GRUN, R. (1983): ESR dating in Quaternary
some cases on only a few results. For a more pre-
geology. Ouat Sci Rev., 2: 157-238, Oxford.
cise classification of these units more ESR-
HOROWITZ, Y. (Ed.): Thermoluminescence and Thermolumi-
investigations have to be carried out (up to about
nescent Dosimetry. Vol 11: 222 p., CRC Press, Boca Raton.
IKEYA, M. (1978): Electron spin reconance as a rnethod of dating.
10 per unit). A comparison of the ESR-results with
Archaeornetry, 20: 147-158.
the geological settings and mineralogical investi-
MARFUNIN, A. S. (1979): Spectroscopy. Lurninescence and
gations will be sarried out in collaboration with the
Radiation Centers in Minerals. 352 p., Springer, Berlín.
Department of Geology, University of Palma de
MAROTO, A. L. & FONT, A. (1981): «Proyecto Hades)) desarrollo
de las campañas de 1981. Endins, 8: 81-90.
Mallorca. Nevertheless, a preliminaty comparison
POMAR, L.; GINÉS, A. & FONTARNAU, R. (1976): Las cristali-
(POMAR, pers. comm.) showed rather promising
zaciones freáticas. Endins, 3: 3-25.
aspects. Additionally, it is planned to carry out a
POMAR, L.; GINÉS, A. & GINÉS, J. (1979): Morfología, estruc-
comparison with 6%- and 6180- data as deter-
tura y origen de los espelotemas epiacuáticos. Endins, 5-6:
mined by the Niedersachsisches Landesamt für
3-17.
SHACKLETON, N. J. & OPDYKE, N. D. (1973): Oxygen isotope
Bodenforschung, Hannover. For future work, pa-
and paleomagnetic stratigraphy of equatorial Pacific core
leomagnetic investigations seem also to be very
V28-238: Oxygen isotope temperatures and ice volumes on a
promising, because the ESR-results do not exclude
105 year and 106 scale. Ouat. Res., 3: 39-55.
a paleomagnetic reversal.
SIEGELE, R. & MANGINI, A (1985): ESR studies on foraminifera
in deep-sea sediments. Nucl. Tracks (in press).
SWART, P. K. & HUBBART, J. A. E. B. (1982): Ulranium in Skle-
ractinian coral skeletons. Coral Reefs, 1: 13-19.
Acknowledgement
I wish to thank Dr. L. Pomar, Mallorca, for pro-
viding the core. The U-series results were kindly
provided by Dr. G. J. Hennig and Prof. M. A. Geyh,
Hannover. I am grateful to Prof. K. Brunnacker,
Koln, for his longstanding support and Prof. H.
P. Schwarcz, Hamilton, for his help on the manus-
cript. I am acknowledged to the Deutsche For-
schungsgemeinschaft, the Bundesministerium für
Forschung und Technologie, and NSERC for finan-
cial support.