Studies of Quaternary Deposits in Investigation Trench OL-TK19 on ...
Transcript of Studies of Quaternary Deposits in Investigation Trench OL-TK19 on ...
July 2013
Working Reports contain information on work in progress
or pending completion.
The conclusions and viewpoints presented in the report
are those of author(s) and do not necessarily
coincide with those of Posiva.
Pekka Huhta
Geological Survey of F inland
Working Report 2012-101
Studies of Quaternary Deposits in InvestigationTrench OL-TK19 on the Olkiluoto Study Site,
Eurajoki, SW Finland
ABSTRACT The Quaternary deposits in investigation trench OL-TK19 were studied by the Geological Survey of Finland in October 2012. Samples for grain size determinations were taken from 3 vertical profiles, placed about 20-25 m apart along the trench. Two till units was sampled separately. The profiles extended from the soil surface down to bedrock. The samples were first dried in the laboratory after which they were sieved. In addition, the grain size distribution of the < 63 µm fraction was analyzed with the Sedigraph 5100 instrument. Sedimentological observations of the sampling profiles were documented in field by drawing them on a field observation form and the profiles were photographed using a digital camera. In addition, the excavated section was photographed along its whole length. The till cover in OL-TK19 consists of two parts. The surface layer of the till is oxidized, brownish grey sandy till, whereas the lower layer is unoxidized, grey silty till. Dark grey silty till as in the bottom of investigation trenches OL-TK13 and OL-TK14 was not found in this trench. The till layers in OL-TK19 was deposited in the last flow phase of the Weichselian continental ice. Bedrock striations indicate that the ice moved in a NW-SE direction. The till beds smooth bedrock topography. The tills showed no signs of disturbance related to bedrock movements. Keywords: Overburden, glacial geology, till, stratigraphy, trench, grain size, Quaternary, Finland; Province of Western Finland; Satakunta; Eurajoki; Olkiluoto.
Maaperätutkimukset tutkimuskaivannossa OL-TK19 Olkiluodon alueella Eurajoella Lounais-Suomessa TIIVISTELMÄ Olkiluodon tutkimuskaivanto OL-TK19 tutkittiin lokakuussa 2012. Kaivannoista otet-tiin lapiolla raesuuruusnäytteet noin 20-25 metrin välein vertikaalisesti läpi koko moreenipeitteen kallioon asti 3:sta paikasta. Näytteet otettiin jokaisesta moreeni-yksiköstä. Laboratoriossa näytteet kuivattiin, jonka jälkeen ne seulottiin. Seulottu alle 63 mikronin osanäyte analysoitiin Sedigraph 5100-laitteella.
Jokainen näytteenottoprofiili kuvattiin piirtämällä lomakkeelle ja digitaalikameralla. Lisäksi tutkimuskaivanto kuvattiin kameralla päästä päähän.
Tutkimuskaivannosta OL-TK19 löydettiin vain viimeisen jäätiköitymisvaiheen moree-nipatja. Moreeni koostuu kahdesta kerroksesta. Pintaosassa on hapettunut, ruskean-harmaa hiekkamoreeni. Alempi kerros on hapettumaton, harmaa silttimoreeni. Tutki-muskaivannoista OL-TK13 ja OL-TK14 pohjalta löytynyttä tumman harmaata silttimoreenia ei tästä kaivannosta havaittu.
Moreenin kerrostanut jäätikkö on uurresuuntien perusteella virrannut luoteesta kaak-koon. Maastossa moreenipeite tasoittaa kalliopinnan epätasaisuudet.
Mitään merkkejä postglasiaalisista siirroksista ei moreenipeitteestä tai paljastetusta kallion pinnasta löydetty, eikä moreenissa havaittu kallioperän liikuntoihin viittaavia häiriörakenteita
Avainsanat: Maapeite, glasiaaligeologia, moreeni, stratigrafia, kaivannot, raekoko, kvartääri, Suomi; Länsi-Suomen lääni; Satakunta; Eurajoki; Olkiluoto.
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TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ 1 INTRODUCTION ................................................................................................ 2 2 SAMPLING AND GRAIN SIZE DETERMINATIONS .......................................... 3 3 RESULTS OF INVESTIGATION ........................................................................ 4 4 SUMMARY ......................................................................................................... 6 REFERENCES ............................................................................................................ 7 APPENDICES .............................................................................................................. 8
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1 INTRODUCTION
The Quaternary deposits in investigation trench OL-TK19 were studied by the Geological Survey of Finland in October 2012. Samples for grain size determinations were taken from 3 vertical profiles, placed 20-25 m apart along the trench. Same places were also sampled for mineralogical studies in GSF. Sedimentological observations of the sampling profiles were documented in field by drawing them on a field observation form and the profiles were photographed using a digital camera. In addition, the excavated section was photographed along the whole length. Sampling profiles are numbered OL-TK19- 01 – 03. The coordinates of the sampling profiles are shown in Appendix 1 and the locations in Appendix 2. The location of each sampling profile was determined with the help of start and end points of sections pre-determined for bedrock mapping. The observation forms and the grain size analyses of each profile are presented in the Appendices 3 – 11 of this report.
An observation form is designed to standardize the recording of field data. Till properties (compactness, stone content, stone size, roundness of clasts) are classified on a five degree scale, on which 1 refers to the lowest and 5 to the highest degree of the property (Hirvas 1991).
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2 SAMPLING AND GRAIN SIZE DETERMINATIONS
Samples for grain size determinations were taken from vertical profiles. An amount of 3 to 4 kg of sediment was taken with a shovel and placed in plastic bags for transport to the laboratory. The samples were first dried in the laboratory. Grains over 6.3 mm were extracted before analysis. The samples were first sieved and then the grain size distribution of the < 63 µm fraction was analyzed with the Sedigraph 5100 instrument.
Table 1 shows the soil sampling depths and the soil type classification in OL-TK 19. RT- soil type classification after Aaltonen et al. 1949 and geotechnical (GEO) - classification after Korhonen et al. 1974.
Table 1. Soil sampling sites and their sampling depths and soil type classification in OL-TK 19.
Profile depth in Soil type classification
metres d50 (GEO) geotechnical (RT)
OL-TK19 01 0.4-0.8 sandy till fine sandy till OL-TK19 01 1.4-1.8 silty till fine sandy till OL-TK19 02 0.6-1.0 sandy till fine sandy till OL-TK19 02 1.4-1.8 sandy till fine sandy till OL-TK19 02 2.0-2.4 silty till fine sandy till OL-TK19 03 0.4-0.8 sandy till fine sandy till
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3 RESULTS OF INVESTIGATION
A total of 3 profiles from northwest to southeast were sampled from the investigation trench OL-TK19, which was approximately 85 m long. The height of the profiles varied between 2.8 m and 1.0 m. A summary of the sampling profiles is presented in Fig. 1.
Figure 1 shows how the till cover very effectively smooth out the bedrock topography. The till cover in OL-TK19 consists of two layers. The surface layer is oxidized, brownish grey sandy till. The upper till layer is classified as having a normal amount of cobbles and boulders, with the size of the larger clasts ranging from ø 6 to 20 cm. The edges of the clasts are eroded and rounded. The upper till displays normal compactness.
The lower till layer is compact grey silty till with over 11.8 % of fine material (under 0.002 mm). The lower till is classified as having a normal amount of cobbles and boulders, with the size of the larger clasts ranging from ø 6 to 20 cm. The edges of the clasts are eroded and rounded (Fig. 2). Dark grey silty till as in the bottom of investigation trenches OL-TK13 and OL-TK14 was not found in this trench.
Figure 1. Summary of sampling profiles OL-TK 19 - 01 – 03. Numbers at the bottom are bolts in bedrock.
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
9,0
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
P16
P17
P18
P19
P20
P21
P22
P23
m asl
OL TK‐19
z ground surface
z grey till
z bedrock
TK19‐3
TK19‐2 TK19‐1
5
Till cover is overlain in places by thin gravel/sand layers derive from littoral phase when sea level was lowering. The silt layer at the bottom of profile OL-TK19-2 dates possibly back to some warmer phase of Weichselian.
No signs of postglacial faults were detected either in the tills or in the exposed bedrock. The tills showed no signs of disturbance related to bedrock movements.
Figure 2. Two till layers in profile OL-TK19-2. The shovel is 1.1 m long.
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4 SUMMARY
Two till layers were found in trench OL-TK19 in Olkiluoto. The surface layer is oxidized, brownish grey sandy till, whereas the lower layer is unoxidized, grey silty till.
The till layers were deposited in the last flow phase of the Weichselian continental ice. Bedrock striations indicate that the ice moved in a NW-SE direction. The silt layer at the bottom of profile OL-TK19-2 dates possibly back to some warmer phase of Weichselian.
No signs of postglacial faults were detected either in the tills or in the exposed bedrock. The tills showed no signs of disturbance related to bedrock movements.
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REFERENCES
Aaltonen, V.T., Aarnio, B., Hyyppä, E., Kaitera, P., Keso, L., Kivinen, E., Kokkonen, P., Kotilainen, M.J., Sauramo, M., Tuovila, P. & Vuorinen, J., 1949. Maaperäsanaston ja maalajien luokituksen tarkastus v. 1949. Summary: A critical review of soil terminology and soil classification in Finland in the year 1949. Maataloustieteellinen Aikakauskirja: 21, 37 – 66. Hirvas, H., 1991. Pleistocene stratigraphy of Finnish Lapland. Geological Survey of Finland, Bulletin 354. 123 p., 75 figs., 9 tables and 2 appendices. Huhta, P., 2008. Studies of Quaternary Deposits of Investigation Trench OL-TK13 at the Olkiluoto Study Site, Eurajoki, SW Finland. Posiva Oy. Working Report 2007-34. Huhta, P., 2007. Studies of Quaternary Deposits of Investigation Trench OL-TK14 at the Olkiluoto Study Site, Eurajoki, SW Finland. Posiva Oy. Working Report 2008-31. Korhonen, K.-H., Gardemeister, R. & Tammirinne, M., 1974. Geotekninen maalajiluokitus. Geotekniikan laboratorio, tiedonanto 14, 20 s. 2 liitettä.
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APPENDICES
Appendix 1. Coordinates of the soil sampling profiles in trench OL-TK19. Appendix 2. Location of sampling profiles OL-TK19-01 – 03. Location of investigation trenches OL TK13, OL TK14 and OL TK19. Appendix 3 – 5. Field observation forms OL-TK19-01 – 03. Appendix 6 – 11. Grain size analyses of trench OL-TK19.
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Appendix 1 Coordinates (KKJ1) of the soil sampling profiles in trench OL-TK19.
Profile x y z OL-TK19-01 6792475 1525931 6.8 OL-TK19-02 6792461 1525954 6.7 OL-TK19-03 6792452 1525970 7.5
Notes for field observation forms: GS = sample for grain size analysis CO = compactness ST = stone content SSZ = stone size RO = roundness of clasts WB = weathered bedrock Used grain diameters in mm: grain diameter mm geotechnical (geo) construction technical (rt) classification 20 - 2 gravel gravel 2 - 0.6 sand sand 0.6 - 0.2 sand sand 0.2 - 0.06 sand fine sand 0.06 - 0.02 silt fine sand 0.02 - 0.006 silt silt 0.006 - 0.002 silt silt under 0.002 clay clay
10
Appendix 2
Location of sampling profiles OL-TK19-01 – 03. Map data by the National Land Survey of Finland.
11
Location of investigation trenches OL-TK13, OL-TK14 and OL-TK19. Map data by the National Land Survey of Finland.
PA
TFH
MR
SB
S2
GS
GC
SSS
dmC
OS
TS
SZ
RO
Dire
ctio
nO
bser
vatio
ns0 10
33
33
20 30
Geo
logy
till c
over
Dire
ctio
n
Type
of e
xpos
ure
exca
vatio
n
A
UTH
OR
P
. Huh
ta
OB
SE
RV
ATI
ON
№ T
K 1
9-01
D
ATE
3
0102
012
AP
PE
ND
IX 3
Loca
tion
OLK
ILU
OTO
TK
19
Stru
ctur
e
grey
ish
brow
n
Col
our
Coo
rdin
ates
X: 6
7924
75
Y
: 152
5931
Z:
6.8
E
LEV
ATI
ON
bedr
ock
till
strg
Lith
olog
y
Map
shee
t
Fiel
d an
alys
Sam
ples
Pro
file
30 40 50 60
12
PA
TFH
MR
SB
S2
GS
GC
SSS
dmC
OS
TS
SZ
RO
Dire
ctio
nO
bser
vatio
ns0
33
33
10
43
33
20
pale
brow
n30
Map
shee
t
Fiel
d an
alys
Sam
ples
Pro
file
strg
Lith
olog
y
till
till
silt
Coo
rdin
ates
X: 6
7924
61
Y
: 152
5954
Z:
6.7
E
LEV
ATI
ON
Col
our
brow
n(o
xidi
zed) gr
ey(u
noxi
dize
d)
Loca
tion
OLK
ILU
OTO
TK
19
Stru
ctur
e
mas
sive
Geo
logy
till c
over
Dire
ctio
n
Type
of e
xpos
ure
exca
vatio
n
A
UTH
OR
P
. Huh
ta
OB
SE
RV
ATI
ON
№ T
K 1
9-02
D
ATE
3
0102
012
APP
EN
DIX
4
30 40 50 60
bedr
ock
13
PA
TFH
MR
SB
S2
GS
GC
SSS
dmC
OS
TS
SZ
RO
Dire
ctio
nO
bser
vatio
ns0
44
33
10St
riatio
ns30
0 - 3
10°
20 30
Map
shee
t
Fiel
d an
alys
Sam
ples
Pro
file
strg
Lith
olog
y
till
bedr
ock
Coo
rdin
ates
X: 6
7924
52
Y
: 152
5970
Z:
7.5
E
LEV
ATI
ON
Col
our
grey
ish br
own
Loca
tion
OLK
ILU
OTO
TK
19
Stru
ctur
e
Geo
logy
till c
over
Dire
ctio
n
Type
of e
xpos
ure
exca
vatio
n
A
UTH
OR
P
. Huh
ta
OB
SE
RV
ATI
ON
№ T
K 1
9-03
D
ATE
3
1102
012
APP
EN
DIX
5
30 40 50 60
14
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163131Order ID : 40023Customer Sample ID : TK19-1 PINTACustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 24.00651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 32.1 0.0200 23.8 0.0020 8.46.3000 100.0 0.0600 31.0 0.0160 22.1 0.0010 5.22.0000 87.7 0.0500 30.6 0.0100 18.6 0.0006 3.70.6300 71.5 0.0400 29.3 0.0060 15.30.2000 51.8 0.0300 27.1 0.0040 12.7
15 Appendix 6
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163132Order ID : 40023Customer Sample ID : TK19-1 POHJACustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 18.23651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 54.9 0.0200 45.8 0.0020 14.26.3000 100.0 0.0600 53.8 0.0160 43.6 0.0010 6.12.0000 93.4 0.0500 53.4 0.0100 38.7 0.0006 3.20.6300 85.1 0.0400 52.2 0.0060 32.90.2000 71.9 0.0300 49.7 0.0040 27.1
16 Appendix 7
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163133Order ID : 40023Customer Sample ID : TK19-2 PINTACustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 23.50651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 41.1 0.0200 32.6 0.0020 13.06.3000 100.0 0.0600 40.1 0.0160 30.8 0.0010 7.62.0000 87.5 0.0500 39.5 0.0100 27.2 0.0006 5.40.6300 74.5 0.0400 38.1 0.0060 23.40.2000 58.1 0.0300 35.8 0.0040 20.0
17 Appendix 8
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163134Order ID : 40023Customer Sample ID : TK19-2 KESKICustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 22.87651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 46.9 0.0200 37.0 0.0020 13.36.3000 100.0 0.0600 45.8 0.0160 34.7 0.0010 7.12.0000 93.4 0.0500 45.3 0.0100 30.2 0.0006 4.80.6300 82.2 0.0400 43.8 0.0060 25.70.2000 66.9 0.0300 41.1 0.0040 21.7
18 Appendix 9
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163135Order ID : 40023Customer Sample ID : TK19-2 POHJACustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 11.06651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 51.6 0.0200 38.5 0.0020 11.86.3000 100.0 0.0600 50.5 0.0160 35.6 0.0010 7.32.0000 96.2 0.0500 49.7 0.0100 29.9 0.0006 5.50.6300 89.5 0.0400 47.7 0.0060 23.50.2000 75.0 0.0300 44.1 0.0040 18.9
19 Appendix 10
Labtium OyP.O. Box 1500Neulaniementie 5FI-70211 KUOPIO, FINLANDtel +358 10 653 8000fax +358 10 653 8489
Laboratory Sample ID : L12163136Order ID : 40023Customer Sample ID : TK19-3 POHJACustomer : GTK Va 212 Pekka Huhta
7.12.2012________________________
Grains >6.3 mm were extracted before analysis.
650G Determination and removal of coarse fraction (%) 25.26651 Wet sieving OK
Sedigraph analysis (658)Dry sieving ISO 3310/1 (652)
2020.20.020.0020.0002 60.60.060.0060.0006
90
75
50
25
10
%GEO
RAK
Clay Silt Sand Gravel
Clay Silt Fine Sand Sand Gravel Gravel
D (mm) % D (mm) % D (mm) % D (mm) % D (mm) %20.0000 100.0 0.0630 38.4 0.0200 28.6 0.0020 10.46.3000 100.0 0.0600 37.3 0.0160 26.6 0.0010 6.22.0000 89.3 0.0500 36.7 0.0100 22.7 0.0006 4.20.6300 76.0 0.0400 35.1 0.0060 18.90.2000 58.8 0.0300 32.4 0.0040 15.9
20 Appendix 11