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.

1

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

2

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).

3

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

4

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.

6

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.

7

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.

8

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.

9

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


Laboratory Sample ID : L12163132Order ID : 40023Customer Sample ID : TK19-1 POHJACustomer : GTK Va 212 Pekka Huhta

7.12.2012________________________




2020.20.020.0020.0002 60.60.060.0060.0006

90

75

50

25

10

%GEO

RAK




16 Appendix 7


Laboratory Sample ID : L12163133Order ID : 40023Customer Sample ID : TK19-2 PINTACustomer : GTK Va 212 Pekka Huhta

7.12.2012________________________




2020.20.020.0020.0002 60.60.060.0060.0006

90

75

50

25

10

%GEO

RAK




17 Appendix 8


Laboratory Sample ID : L12163134Order ID : 40023Customer Sample ID : TK19-2 KESKICustomer : GTK Va 212 Pekka Huhta

7.12.2012________________________




2020.20.020.0020.0002 60.60.060.0060.0006

90

75

50

25

10

%GEO

RAK




18 Appendix 9



7.12.2012________________________




2020.20.020.0020.0002 60.60.060.0060.0006

90

75

50

25

10

%GEO

RAK




19 Appendix 10



7.12.2012________________________




2020.20.020.0020.0002 60.60.060.0060.0006

90

75

50

25

10

%GEO

RAK




20 Appendix 11

studies of quaternary deposits in investigation trench ol-tk19 on

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