147
CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE GRUND FORMATION
GEOLOGICA CARPATHICA, 55, 2, BRATISLAVA, APRIL 2004
147153
CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE GRUND
FORMATION (MOLASSE BASIN, LOWER AUSTRIA)
STJEPAN ÆORIÆ
1
and LILIAN VÁBENICKÁ
2
1
Department of Paleontology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria; stjepan.coric@univie.ac.at
2
Czech Geological Survey, Klárov 131/3, 118 21 Prague, Czech Republic; svab@cgu.cz
(Manuscript received June 5, 2003; accepted in revised form December 16, 2003)
Abstract: The calcareous nannoplankton was studied in samples from the Grund Formation type locality (sections B, F,
G and H). Samples from Grund-Windmühlberg (W1W4) were further collected and investigated. The nannofossil
assemblages are characterized by biostratigraphically important Helicosphaera waltrans, H. walbersdorfensis and the
rare occurrence of discoasterids. Although the marker species Sphenolitus heteromorphus is absent in all samples, the
composition of nannofossils enables specification of these deposits as Biozone NN5 of Martini (Lower Badenian).
Regular presence of H. waltrans, which is usually limited to a short stratigraphic interval within nannoplankton Zone
NN5, enables attribution of these sediments to the Helicosphaera waltrans Horizon (vábenická 2002).
Key words: Badenian, Austria, Molasse Basin, Grund Formation, calcareous nannofossils, NN5 Nannoplankton Zone.
Introduction
The Grund Formation is characterized by the change between
sand and clay-silt sediments. Roetzel & Pervesler (2004) de-
scribed the geological situation of the study area in detail. The
sandy shell layers, with erosion surfaces at the base and grad-
ed bedding were interpreted as proximal tempestites (Zuschin
et al. 2001), whereas intercalated clay-silt layers present prod-
ucts of quiet water paleoconditions. Biostratigraphic evalua-
tion of the Grund Formation was the subject of investigations
by many authors recently and earlier. vábenická & Ètyroká
(1998, 1999) investigated foraminiferal and nannoplankton
contents of the Karpatian and Lower Badenian sediments in
the Alpine-Carpathian Foredeep. They subdivided the equiva-
lent deposits of the Grund Formation in a lower part (with
Helicosphaera waltrans, H. walbersdorfensis and scarce H.
ampliaperta) and an upper part (with relatively common H.
waltrans). Calcareous nannofossil assemblages from fine clas-
tic sediments from the excavation on the type locality Grund
(organized by the Institute of Paleontology, Vienna) and from
Grund-Windmühlberg were studied recently to clarify the
stratigraphic position of the Grund Formation. Our attention
was focused especially on the occurrence of the nannofossil
species Helicosphaera waltrans and the importance of its
stratigraphic range.
Methods
Smear slides were analysed using a light microscope (1000
×
magnification) at normal and crossed nicols. Suspension slides
were prepared by two different laboratory procedures. Before
preparation, samples W1W4 and sediments from section B
were treated by ultrasound in distilled water for a few seconds.
Suspension slides for sections F, G, and H were prepared using
a decantation method (as mentioned in vábenická 2002a).
Quantitative data were obtained under the microscope by
counting specimens per view field. The term Miocene s.s.
(= sensu stricto) taxa is used for nannofossil species the first
occurrence of which is known in the Miocene. Long-ranging
species that occur first in the Paleogene and extend to the Mi-
ocene are expressed under the term taxa with their last occur-
rence mentioned during the Miocene. These nannofossils
may belong to the autochthonous assemblage or they can be
reworked from older strata.
For biostratigraphic determination, the standard NN zones
of Martini (1971), Mediterranean nannofossil zones MNN of
Fornaciari et al. (1996), and correlations of Young (1998)
were applied.
Abundances of the calcareous nannoplankton are recorded
in Table 1a,b for the section B and samples W1W4, and Ta-
ble 2 for the sections F, G and H (A = abundant: dominant
species with more than 50 % of an assemblage; C = common:
1050 %; F = few: <10 % of an assemblage; R = rare: only a
few specimens were found; ? = questionable species; f = spec-
imens mostly in fragments; B = barren: no specimen was
found in a sample).
The preservation of the calcareous nannoplankton assem-
blage is characterized by the following terms: G = good, no
evidence of etching or overgrowth; M = moderate, etching or
overgrowth is apparent; P = poor, significant etching or over-
growth.
Results
The material for nannofossil studies originates from silts
and fine sands of the Grund locality, containing sections: B, F,
148 ÆORIÆ and VÁBENICKÁ
G, and H (Fig. 1). Samples W1W4 were collected in old
wine cellars, which are situated at Windmühlberg, approxi-
mately 900 m westwards of the excavation sections F, G and H.
Calcareous nannofossils are generally abundant and well
preserved in the lower part of section B (samples GRU-B2-1a
to GRU-B2-6) (Fig. 2). These samples are characterized by
common to abundant Reticulofenestra minuta. The accompa-
nying assemblage includes Coccolithus pelagicus and regu-
larly found but rare Helicosphaera carteri, H. walbersdorfen-
sis, H. waltrans, H. vedderi, Reticulofenestra haqii, and
Syracosphaera pulchra. Coronocyclus nitescens, Cyclicar-
golithus floridanus, Helicosphaera euphratis, H. granulata,
H. mediterranea, Holodiscolithus macroporus, Pontosphaera
multipora, Reticulofenestra gelida, R. pseudoumbilica, Rhab-
dosphaera sicca, and Sphenolithus moriformis occur irregu-
larly (Table 1a).
Calcareous nannofossil assemblages from the upper part of
the Grund B section (samples GRU-B2-7 and GRU-B2-8) are
generally scarce and poorly preserved. Only a few specimens
of Coccolithus pelagicus, Reticulofenestra minuta and Syra-
cosphaera pulchra could be identified.
Investigation of samples from Windmühlberg (W1W4)
yielded abundant, well preserved nannoplankton assemblag-
es, similar to the lower part of the section B. Moreover, Dis-
coaster variabilis and D. challengeri occur rarely in samples
W3 and W4 (Table 1b).
Autochthonous assemblages were complemented by re-
worked nannofossils both in localities of Grund, section B and
Grund-Windmühlberg. The allochthonous component forms
up to 30 % of the entire assemblages in section B and in sam-
ples W1W4. It is represented by Paleogene (Reticulofenestra
stavensis, R. bisecta, Cribrocentrum reticulatum, Chiasmo-
lithus solitus, Zygrhablithus bijugatus, Discoaster multiradia-
tus etc.) and Cretaceous taxa (Cribrosphaerella ehrenbergii,
Retacapsa sp., Watznaueria barnesae, W. manivitae etc.).
Sediments from sections F and G provided assemblages (1
20 specimens per view field of the microscope at 1000
×
) of
medium-well or poorly preserved calcareous nannofossils.
Only scarce nannofossils were found in sediments of section H
with the exception of the sample CI-H-1 taken from the exca-
vation bottom. The overlying sediments either provided scarce
specimens mostly reworked from older strata or they were bar-
ren of nannofossils.
The nannofossil assemblages of section F, G, and H are
characterized by abundance of Coccolithus pelagicus and high
numbers of reworked specimens. Miocene associations are
formed by relatively common Helicosphaera carteri and H.
waltrans. They are accompanied by small reticulofenestrids
(R. minuta, R. haqii, R. pseudoumbilica <5 µm), rare occur-
rences of Discoaster variabilis, Syracosphaera sp.,
Pontosphaera multipora, Umbilicosphaera rotula, and by the
irregular occurrence of Helicosphaera walbersdorfensis.
Fig. 1. Excavations at the type locality of the Grund Formation, Grund and Grund-Windmühlberg wine cellars (inserted map).
149
CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE GRUND FORMATION
Fig. 2. Light microscope photographs of calcareous nannofossils from Grund excavations and GrundWindmühlberg. 1 Braaru-
dosphaera bigelowii (Gran et Braarud, 1935) Deflandre, 1947; Sample B-2-1b, crossed polarized light. 2 Reticulofenestra gelida (Gei-
tzenauer, 1972) Backman, 1978; Sample B-2-1b, crossed polarized light. 3 Reticulofenestra pseudoumbilica (Gartner, 1967) Gartner
1969; Sample B-2-1b, crossed polarized light. 4 Reticulofenestra haqii Backman, 1978; Sample B-2-1b, crossed polarized light. 5
Reticulofenestra minuta Roth, 1970; Sample B-2-1b, crossed polarized light. 6, 7 Umbilicosphaera jafari Müller, 1974; Sample B-2-1b.
6. crossed polarized light; 7. parallel light. 810 Helicosphaera waltrans Theodoridis, 1984; 8. Sample B-2-1b, crossed polarized light. 9.
Sample B-2-1b, parallel light. 10. Sample W-3, crossed polarized light. 11 Helicosphaera walbersdorfensis Müller 1974; Sample B-2-1b,
crossed polarized light. 12, 13 Rhabdosphaera sicca Stradner, 1963; Sample B-2-1b; 12. parallel light; 13. crossed polarized light. 14
Reticulofenestra bisecta (Hay et al., 1966) Roth, 1970; reworked specimen, sample B-2-1b, crossed polarized light. 15 Lithostromation
perdurum Deflandre, 1942; Sample B-2-1b, parallel light. 16 Discoaster variabilis Martini et Bramlette, 1963; Sample W-3, parallel
light. 17 Discoaster challengeri Bramlette et Riedel, 1954; Sample W-4, parallel light. 18, 19 Coccolithus pelagicus (Wallich, 1871)
Schiller, 1930; Sample W-3. 18. crossed polarized light; 19. parallel light. 20, 21 Helicosphaera carteri (Wallich, 1877) Kamptner, 1954;
Sample B-2-1b. 20. crossed polarized light; 21. parallel light. 22, 23 Syracosphaera pulchra Lohmann, 1902; Sample B-2-1b. 22. parallel
light; 23. crossed polarized light.
150 ÆORIÆ and VÁBENICKÁ
Table 1: a Abundance of calcareous nannofossils at the type locality of the Grund Formation section B. b Abundance of calcar-
eous nannofossils in samples from Windmühlberg.
Scarce specimens of Helicosphaera mediterranea, H. euph-
ratis, H. granulata, and reworked Helicosphaera ampliaperta
were recorded (Table 2).
Miocene s.s. specimens from section F, G and H represent
about 30 % of the oryctocoenoses, and are complemented by
numerous reworked nannofossils from the Upper Cretaceous
and Paleogene strata.
The absence or scarcity of discoasterids in investigated sed-
iments, which indicate open ocean conditions, confirms shal-
low paleoenvironment documented by other fossil groups.
Relatively high number of reworked specimens especially in
samples from sandy beds does not allow satisfactory paleo-
ecological interpretation.
Discussion
Theodoridis (1984) highlighted the short phase of the
Helicosphaera waltrans occurrence and correlated it with
Zone NN5 (sensu Martini 1971). In the Mediterranean, H.
waltrans is restricted to the short interval that spans the up-
per part of Subzone MNN5a and the lower part of MNN5b
attributed to the Langhian (Fornaciari et al. 1996), which
corresponds to the middle part of Zone NN5 (Young 1998).
There is no doubt that H. waltrans also forms a significant
and short horizon in the Alpine-Carpathian Foredeep; never-
theless, its precise stratigraphic correlation is still under dis-
cussion. The rare presence of Helicosphaera ampliaperta
may be explained here as a reworked component in orycto-
coenoses from the older strata. Zone NN5 is correlated with
the Lower Badenian of the regional stratigraphic classifica-
tion of the Central Paratethys (Rögl 1998). The presence of
Helicosphaera waltrans and the scarcity of reworked H. am-
pliaperta in samples from section B, F, G and H as well as in
four samples from Windmühlberg (W1W4) indicate nanno-
plankton Zone NN5 although the stratigraphically very im-
portant species Sphenolithus heteromorphus is absent in all
samples.
a
Samples
pr
es
er
va
tio
n
ab
unda
nc
e
Br
aa
ru
do
sp
ha
er
a
bi
ge
lo
w
ii
Ca
lcidis
cus
le
pr
op
or
us
Ca
lcidis
cus
tr
opic
us
Co
ccoli
thus
m
iope
lagic
us
C.
pelag
icus
Co
ronoc
yclu
s nite
scens
Cy
clicar
golit
hus
flor
ida
nus
D
is
coas
ter
sp
.
G
em
inil
ithell
a r
ot
ula
H
elicos
phaer
a car
ter
i
H
. e
uphr
atis
H
. g
ra
nu
lata
H
. m
edi
terra
nea
H.
w
al
be
rs
dor
fe
ns
is
H
. w
altr
ans
H
. vedd
eri
H
olodis
colith
us
m
acr
op
or
us
Li
thos
tr
om
at
ion p
er
dur
um
Po
ntos
phaer
a dis
copor
a
P.
m
ulti
por
a
Po
ntos
phaer
a
sp
.
Re
ticulo
fenes
tr
a g
elida
R.
haqii
R.
m
in
ut
a
Re
ticulo
fenes
tr
a p
seudo
um
bi
lica
Re
ticulo
fenes
tr
a sp.
Rh
abdo
sphae
ra
s
icca
Scy
phos
phae
ra
sp
.
Sph
enol
ithus
m
or
ifor
m
is
Sph
enol
ithus
sp
.
Syr
acos
phaer
a his
tr
ica
Syr
acos
phaer
a pu
lchr
a
Th
or
aco
spha
er
a h
eim
ii
Th
or
aco
spha
er
a
sp
.
Tr
iquetr
or
ha
bdulu
s sp
.
U
m
bilic
os
pha
er
a
jafar
i
GRU-B2-8 P R x x x
GRU-B2-7 P R x x
GRU-B2-6 M F f r r f r r r
GRU-B2-5 G C r f r r r r r r r r r r r c r r r
GRU-B2-4 G F f r r r r r c r r r
GRU-B2-3 G F r f r r r r r c r r r
GRU-B2-2 G C r f r r r r r r r r a r r r
GRU-B2-1c G A r f r r r r r r r r r r c r r r r
GRU-B2-1b G A r r r r r r r r r r r r r r r r a r r r r r r r
GRU-B2-1a G A r r/f r r r r r r r r r r r r a r r r r r r
Sample
pr
es
erva
tion
abunda
nce
C
alc
idis
cu
s tr
opic
us
C
oc
co
lithus
m
iop
elagic
us
C. pel
agi
cus
Coronocycl
us ni
te
scens
C
yclicar
golithus
flor
idanus
D
is
coas
ter
challe
nger
i
D
is
coas
te
r v
ar
iab
ilis
D
isco
as
te
r sp
.
H
elicos
phaer
a ca
rter
i
H
. w
alber
sdor
fen
sis
H
. w
altr
ans
H
. vedder
i
H
olodis
colithus
m
acr
opor
us
Lithos
tr
om
ation p
er
dur
um
P. m
ultipor
a
Re
tic
ulofe
ne
str
a g
elida
R. haqii
R. m
inuta
Re
ticulofenes
tr
a p
seudoum
bilica
Re
ticulofenes
tr
a
sp
.
Rhabdos
phaer
a p
ro
cer
a
Rhabdos
phaer
a s
icca
Syr
acos
phaer
a hi
str
ica
Syr
acos
phaer
a pu
lchr
a
Thor
acos
phaer
a s
axea
Thor
acos
phaer
a
sp
.
Tr
iquetr
or
habdul
us
sp
.
U
m
bilicos
phaer
a jafar
i
W4
G A r r r r r r r a r
W3
G A c r r r r r r r r r a r r r r r r r r
W2
G A r r r r r r r r r r r f a r r r r r
W1
G A r r r r r r r r r r a r r r r
b
151
CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE GRUND FORMATION
GRUND
Horizon Helicosphaera waltrans
sample No.
CI-F-1 CI-F-2 CI-F-3 CI-F-4 CI-F-5 CI-F-6 CI-G-1 CI-G-2 CI-G-3 CI-G-4 CI-G-5 CI-G-6 CI-H-1 CI-H-2 CI-H-3 CI-H-4 CI-H-5
sample abundance
C
C
R
R
V
R
C
C
C
C
R
C
R
nannofossil preservation
M
M
P
P
M
P
P
M
P
M
B
P
M
B
B
P
B
Coccolithus miopelagicus
R
R
R
Discoaster druggi
?
?
Discoaster exilis
R
Discoaster variabilis
R
R
R
R
R
R
Helicosphaera ampliaperta
R
R
Helicosphaera carteri
C
C
C
C
R
F
C
C
C
F
Helicosphaera mediterranea
R
Helicosphaera scissura
R
R
R
R
H. scissura-ampliaperta
R
Helicosphaera walbersdorfensis
F
R
R
F
R
Helicosphaera waltrans
C
C
C
C
F
F
C
C
C
R
Reticulofenestra haqii
F
R
R
R
R
R
Reticulofenestra minuta
F
F
F
F
Reticulofenestra minutula
R
F
F
R
Reticulofenestra pseudoumbilicus
R
F
R
R
Syracosphaera sp.
F
F
R
R
F
R
Mi
oce
ne s.s. n
an
no
fo
ss
il ta
xa
Umbilicosphaera rotula
R
F
R
F
R
Braarudosphaera bigelowii
R
R
R
Coccolithus pelagicus
C
A
C
R
A
F
A
A
C
A
F
C
A
Cyclicargolithus floridanus
C
F
F
R
R
F
F
F
Dictyococcites daviesii
F
F
Discoaster deflandrei
R
Helicosphaera euphratis
R
Pontosphaera discopora
R
Pontosphaera multipora
F
F
R
f
F
R
F
F
Rhabdosphaera sp. (fragments)
R
Sphenolithus moriformis
R
R
R
F
Ta
xa
th
eir
la
st
oc
cu
rre
nc
e
is
m
en
tio
ned
d
ur
in
g
th
e M
io
cen
e
Thoracosphaera sp.
R
F
F
R
Table 2: Abundance of calcareous nannofossils at the type locality of the Grund Formation: Profiles F, G and H.
Therefore the assemblages belong to the upper part of the
Helicosphaera waltrans Horizon (vábenická 2002a,b). This
horizon, marked by relatively common H. waltrans and by the
rare presence or absence of Sphenolithus heteromorphus was
described in the Moravian part of the Carpathian Foredeep,
Czech Republic. vábenická (2000) studied sediments from
the Grund Formation and briefly discussed problems of bios-
tratigraphic correlation in the classic Mediterranean area and
the Central Paratethys.
Calcareous nannofossil assemblages from the Lower Bade-
nian sediments of the Gaindorf Formation (Mühlbach Beds),
which replaces the Grund Formation westwards, are also char-
acterized by the occurrence of H. waltrans and scarce S. hetero-
morphus (Æoriæ 2003).
According to Æoriæ (in Rögl et al. 2002), the upper part of
the nannoplankton Zone NN4 is recorded in the lowermost
Badenian of the Styrian and Vienna Basins. Study of the cal-
careous nannoplankton and foraminiferal assemblages from
the drill site Roggendorf-1 (Æoriæ & Rögl 2004) yielded iden-
tical results for the Molasse Basin.
The foraminiferal fauna investigations of sediments from
the Grund sections F and G also confirm the Lower Badenian
age (Spezzaferri 2004).
Qualitative and quantitative expansion of genus Heli-
cosphaera, scarce discoasters and the absence of Sphenolithus
heteromorphus indicate shallow epicontinental sea (Báldi-
Beke 1980).
Conclusion
The nannofossil assemblages of the excavations at Grund
(sections B, F, G, H) and from Grund-Windmühlberg outcrop
(W1W4) are characterized by:
presence of Helicosphaera waltrans (if present, it is rela-
tively common),
irregular occurrence of Helicosphaera walbersdorfensis,
relative abundance of Helicosphaera carteri,
absence of Sphenolithus heteromorphus,
high numbers of small reticulofenestrids (Reticulofen-
stra minuta, R. haqii, R. pseudoumbilica forms <5 µm in
diameter),
scarce occurrence of reworked Helicosphaera ampli-
aperta and H. mediterranea,
rare occurrence of discoasters, and specimens of genera
Umbilicosphaera and Pontosphaera.
This study of nannofossil assemblages indicates that the
Grund Formation belongs to nannoplankton Zone NN5 (Mar-
tini 1971) and is comparable to the Helicosphaera waltrans
Horizon (vábenická 2002a,b).
The character of the nannofossil assemblages, especially
higher numbers of helicosphaers, scarce discoasters and ab-
sence of Sphenolithus heteromorphus indicates shallow epi-
continental sea.
152 ÆORIÆ and VÁBENICKÁ
Acknowledgments: This study was supported by the Austri-
an Science Fund Project P13743-BIO (Project leader Prof. J.
Hohenegger), which was focused on investigations of the pa-
leoecology of the marine Miocene in Austria and by the Grant
Agency of the Czech Republic (Grant No. 205/98/0694 Bio-
stratigraphy and sedimentology of the Lower and Middle Mi-
ocene in the Alpine-Carpathian Foredeep, Lower Austria and
Moravia, project leader I. Cicha). We thank J. Hohenegger,
(University of Vienna), M. Melinte (National Institute of Ma-
rine Geology and Geoecology, Bucharest), A. Nagymarosy
(Eötvös University, Budapest) and F. Rögl (Museum of Natu-
ral History, Vienna) for the review of this paper. For the pro-
vision of the samples, discussion and additional information
we are grateful to I. Cicha (Geological Survey, Praha), P. Per-
vesler (University of Vienna), and to R. Roetzel (Geological
Survey, Vienna).
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Braarudosphaera bigelowii (Gran et Braarud, 1935) Deflandre,
1947
Calcidiscus leptoporus (Murray et Blackman, 1898) Loeblich et
Tappan, 1978
Calcidiscus tropicus Kamptner, 1956
Coccolithus miopelagicus Bukry, 1971
Coccolithus pelagicus (Wallich, 1871) Schiller, 1930
Coronocyclus nitescens (Kamptner, 1963) Bramlette et Wilcoxon,
1967
Cyclicargolithus floridanus (Roth et Hay, 1967) Bukry, 1971
Dictyococcites daviesii (Haq, 1968) Perch-Nielsen, 1971
Discoaster challengeri Bramlette et Riedel, 1954
Discoaster deflandrei Bramlette et Riedel, 1954
Discoaster druggi Bramlette et Wilcoxon, 1967
Discoaster exilis Martini et Bramlette, 1963
Discoaster variabilis Martini et Bramlette, 1963
Discoaster sp.
Geminilithella rotula Kamptner, 1956
Helicosphaera ampliaperta Bramlette et Wilcoxon, 1967
Helicosphaera carteri (Wallich, 1877) Kamptner, 1954
Helicosphaera euphratis Haq, 1966
Helicosphaera granulata (Bukry et Percival, 1971) Jafar et Martini,
1975
Helicosphaera mediterranea Müller, 1981
Helicosphaera scissura Miller, 1981
Helicosphaera vedderi Bukry, 1981
Helicosphaera walbersdorfensis Müller, 1974
Helicosphaera waltrans Theodoridis, 1984
153
CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF THE GRUND FORMATION
Holodiscolithus macroporus (Deflandre, 1954) Roth, 1970
Lithostromation perdurum Deflandre, 1942
Pontosphaera discopora Schiller, 1925
Pontosphaera multipora (Kamptner, 1948) Roth, 1970
Pontosphaera sp.
Reticulofenestra gelida (Geitzenauer, 1972) Backman (1978)
Reticulofenestra haqii Backman, 1978
Reticulofenestra minuta Roth, 1970
Reticulofenestra minutula (Gartner, 1967) Haq et Berggren, 1978
Reticulofenestra pseudoumbilica (Gartner, 1967) Gartner, 1969
Reticulofenestra sp.
Rhabdosphaera procera Martini, 1969
Rhabdosphaera sicca Stradner, 1963
Rhabdosphaera sp.
Scyphosphaera sp.
Sphenolithus moriformis (Brönnimann et Stradner, 1960) Bramlette
et Wilcoxon, 1967
Sphenolithus sp.
Syracosphaera histrica Kamptner, 1941
Syracosphaera pulchra Lohmann, 1902
Syracosphaera sp.
Thoracosphaera heimii (Lohmann, 1919) Kamptner, 1941
Thoracosphaera sp.
Triquetrorhabdulus sp.
Umbilicosphaera jafari Müller, 1974
Umbilicosphaera rotula (Kamptner, 1956) Varol, 1982