9th International Symposium „Topical Problems in the Field of Electrical and Power Engineering“ Pärnu, , June 14-19, 2010

The geological perspectives for Paleozoic carbonate raw material mining in Harjumaa County, Estonia

Angela Notton University of Technology [email protected] Ylo J. Systra Tallinn University of Technology [email protected]

Abstract building materials grew very quickly and reached maximal level, 1800 000m3, in 2007 (Fig.1). After Harjumaa County surrounds a capital-city Tallinn the Ida-Virumaa County with its oil shale mining for and has the highest density of population, more electric power stations about 15 million tons yearly, than 121 residents per 1 km2 .At the same time here Harjumaa County is keeping the second place in is going active mining, mostly different building total mining and the first in raw building material materials: limestone, gravel and sand are mining. In Harjumaa County in 2008 were extracted extracted. At dense population, network roads and carbonate raw materials 1746 000m3 and 49 800m3 railways there are very few places for new quarries, pure limestone for technological use, 289 700m3 of because the places of mineral resources of good building gravel, 1956 700m3 of building sand and quality are occupied by different settlements. By 49 000m2 of sand for fillings. The bigger part of the Estonian laws underground resources belong them was used in civil, industrial and road building. to government and may be easily and without harm The renewing of road network and railways needs to environment extracted. Mined territories after many million tons of building stone, gravel, sand put in order may be returned to owners. In many and other materials. cases the soil conditions after mining is better than At the dense population the best places for quarries before. In this paper are discussed the problems of are occupied by towns, settlements, villages and the Ordovician bedrock mineral resources using, farm houses, so it is the main problem to find places development and their quality in the Harjumaa for new quarries. The local people are very clever to County. In paper are shown volumes of mining, find reasons, why the mineral resources (which by some demands to limestone and dolostone material Estonian laws belong to government) must not be and their properties in some different deposits. mined on their domains and home places. They are involved into expertise foreign specialists, who after receiving rich “compensation” will find Keywords “underground rivers” in every place, wherever it is Carbonate bedrock, Paleozoic, Ordovician, building needed. If there were no protected rare plants, it is stone, limestone, dolostone, technological material, easy to seed them from other areas, only not to give chemical composition, compressive strength rights for mining. The situation needs to be more carefully studied and it is possible, that will be found other territories with needed quality of mineral resources, where the mining is not so painful for Introduction local people. It was the main reason for initiating Harjumaa County covers 4333km2 and is the biggest this doctoral study of different mineral resources in by territory and population in Estonia. Including the the Quaternary sediments and Paleozoic bedrocks capital-city Tallinn with more than 400 000 residents for their economical and more effective usage in the here in 2008 lived 523 400 people or 38.5% of all Harjumaa County. This paper deals only the part of population of Estonia. Ordovician carbonate rock. In Tallinn are concentrated transport junctions to Europe and Russia, industry, education, culture, the Geological setting main harbors and airfield. After receiving back independency and joining the European Union in Harjumaa County is located in the northwestern 2004 was initiated renovation of all types of Estonia, on the southern shore of the Finnish Gulf, transport, road- and railways, airfields and harbors. about 80km to south from Helsinki, Finland. This action was financially supported by EU. For Geologically this area belongs to the southern slope building were needed special materials: aggregate, of the Fennoscandian shield, where the Precambrian gravel, sand etc. From 2001 extracting of different Early Proterozoic crystalline rocks of age 2.0-1.3Ga

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0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Figure1. Volumes of mined carbonate building stone (in thousands m3) in the Harjumaa County (light columns) and total in Estonia (dark columns) , , Nabala, and Väo are listed as from 1994 to 2009 (data about all country are not deposits of all-country importance. As sources of received yet) local importance are registered deposits near Jägala, Kernu, Maardu, Määra, , Sookaera, Valkla (Lehtinen et al, 2005) are covered by sequence of and Sõrve (Rannamõisa). the Ediacaran and Paleozoic sedimentary rocks with In 5 deposits: Munalaskme, Tuula, Rummu, age between 600Ma and 359Ma in Estonia. The Paeküla-Kõmmaste and Vasalemma are registered surface of the Precambrian basement together with also reserves of pure limestone of technological all sedimentary layers is slightly inclined to south, quality (Table1). about 3m per 1km. The sedimentary bedrock cover become thicker to south, it thickness near the Historical using of carbonate rocks in northern seashore is only 100-140m and grows at the southern boundary of county up to 250-280m. The Estonia bedrocks are covered by thin, 5-20m Quaternary cover, usually less than 5m. The first using of local bedrock were fixed at the end The oldest sedimentary bedrocks of Estonia belong of younger Bronze Age, when plate-like carbonate to Ediacaran system, represented here by 630- stones removed from fields and put in piles or a low 542Ma old Vendian complex (Nestor et al, 2007). stone wall around the fields (Perens, Kala, 2007). This time was going Rodinia’s breakup and ancient Some hundred years before our era a limestone wall continent Baltica became the newly independent, but was built on Island to protect the fortified was located near the southern pole (Cocks, Torsvik, settlement of Asva. In ninth-eleventh centuries local 2005). In such very cold climate conditions was limestone was used for building of 7-10m high walls impossible to form carbonate sediments, and it was surround the and Varbola strongholds. The the reason that Vendian complex as well as all length of Varbola wall is 580m. Both forts had deep Cambrian and Lower Ordovician series are here limestone-mantled wells, which are preserved up to represented by sandstones, siltstone and claystone now. From limestone were built graves in the North (Mens, Pirrus, 1997). Only in the beginning of the Estonia, also in the Harjumaa County. After invasion Middle Ordovician 471.8 ± 1.6 Ma Baltica reached of Danish king Valdemar II in 1219 the building of the limestone castle-citadel was at once initiated. more warm latitudes and in shallow continental sea th carbonate sediments began to form (Nestor et al, The works finished in 1227. The 13 century was 2007). The Middle and Upper Ordovician section the time for building numerous limestone churches reaches in the Kerguta (565) drill core, Central in Tallinn, Saaremaa etc. Later the limestone became Estonia, 185m. The whole sequence is represented common as a local building stone. by limestone, dolostone, marl and dolomitic marl. The bedrocks contain iron or phosphorite ooliths Demands to carbonate stone, crushed sometimes and in the Kukruse Stage of Upper and grinded material Ordovician the kerogenous and K-bentonite interbeds are common (Põldvere, 2006). Limestone and dolostone is easy to handle, therefore In the Harjumaa County there are being registered it has been used in buildings fore many hundred 16 carbonate stone deposits, four of them: years. Limestone in road construction is needed in

2 many different stages, aggregate of many fractions cement. Limestone in agriculture is widely used to for layers forming, lime powder as a filler in asphalt improvement of composition and properties of soils, etc. The white road-marking mixture also contains for animal feeds, lime filter drains and garden lime. the limestone powder. Very important are quicklime and slaked lime in Building limestone must be strong to pressure and environmental care for purifying drinking water and resistant to weather and frost, which usually is 25 flue gases, cleaning waste water and industrial waste cycles, in clayey limestone only 15 and in more water, sludge and biological waste treatment, liming strong types of rock reaches 35 cycles (Perens, Kala, of waterways, treatment of contaminated soil, for 2007). As a rule the compressive strength of the covering of landfills, production of heat (Nordkalk, Estonian Ordovician limestone is between 600-800 2007, 2009). For technological limestone demands kg/cm2 (65-85MPa), in more strong types rising up

Table 1. Limestone deposits in the Middle (O2) and are very high to quality and impurities, CaO content Upper Ordovician (O3) succession of the Harjumaa must exceed 52%. County: (DEP- not in use) and (PiW open pits in Pure technological dolostone is needed for glass work). Numbers show next listed in registry production (not less than 18% MgO), for making deposits: 1–Sõrve, 2–Harku, 3–Väo, 4–Maardu, 5– fireproof materials (MgO not less than 19%, CaO Jägala, 6–Valkla, 7–Paeküla-Kõmmaste, 8– not more than 33%, SiO2 not more than 1%, sum of Määra, 9–Rummu, 10–Vasalemma No 1, 11– Al2O3, Fe2O3, Cr2O3 not higher than 2%). Abrasive Vasalemma No 2, 12–Tuula, 13–Sookaera, 14– products for polishing glass, nickel, cupper, pearl Munalaskme, 15–Nabala, 16–Kernu and other soft materials made from dolostone need very pure bedrock: MgO > 19,5%, CaO < 32,5%, to 1200kg/cm2 (about 120MPa) and in clay-rich insoluble remnants not more than 2%. varieties may decrease to 400-200kg/cm2 (about 45- 25MPa). Last type of building stone may be used Chemical composition and physical– only as filling material. For aggregate limestone the strength must be not less than 400kg/cm2. For wall mechanical properties of the carbonate stone are used both limestone and dolostone, in good bedrock in Harjumaa County building stone the thickness of layer must be not less than 10cm. In some types of stone (Lasnamäe Stage) The Middle Ordovician (472-461 Ma) section here is the layer thickness exceeds 20cm limestone, seldom represented by 5 stages (from oldest): Volhov (light 30cm (Vasalemma “marble”) (Perens, Kala, 2007). grey limestone with marl intercalations and multiple For inside using is very important colour and inside green glauconite grains), Kunda (sandy limestone structure of rock. The decorative properties are used with kerogenous kukersite lenses), (limestone in many old buildings and churches in Tallinn and with brown iron ooids), Lasnamäe (grey limestone northern and central Estonia (Perens, 2004). divided by thin clayey films into thin and medium Limestone is needed in mining industry’s processes, thickness beds) and Uhaku (lower part is represented steel and light brick production, in chemical industry by grey medium-bedded limestone with numerous for making calcium chloride, carbide and phosphate, discontinuity surfaces). The building stone in Harku fertilizers, plastics, ceramics, rubber, paint, glass, quarry has a very high properties and quality. In dry glue, glass fibre and sugar, as the main component in 3

Figure2. Location of working quarries and deposits in the Harjumaa County. Numbers show deposits: 1–Sõrve, 2–Harku, 3–Väo, 4–Maardu, 5–Jägala, 6 –Valkla, 7–Paeküla-Kõmmaste, 8–Määra, 9– Rummu, 10–Vasalemma No 1, 11–Vasalemma No Table2. Short average chemical composition of the carbonate rock from different deposits of Väo 2, 12–Tuula, 13–Sookaera, 14–Munalaskme, 15– Formation (in weight %) Nabala, 16–Kernu state it compressive strength reaches 100-145MPa Component CaO MgO Al2O3 + I.R. and more. Water-adsorption capacity is low, usually SiO2 stays between 0.9 and 2.3%. Resources in Harku Deposit quarry are estimated in the 3 parts of deposit. The thickness of economical layer in the Väo Formation Väo quarry* 50.51 0.85 5.94 8.58 and stone quality differ somewhat in every exploration space. In Harku 5th part thickness of Harku 44.81 5.19 - 7.60 extracted layer is 11.3m. The compressive strength quarry in dry rock is 130-186 MPa, average 154MPa. After water saturation the compressive strength was 71- Maardu 45.04 3.03 11.48 - 135MPa, average 108MPa. The water-adsorption quarry (+Fe2O3) capacity is an average 1.4%, density 2.72-2.74g/cm3 and porosity – between 3.6-5.5%, an average 4.5%. Jägala 44.33 14.55 - 14.36 The frost resistance is 25 cycles, after that the deposit strength stays quite high, an average 105MPa. Estimated resources are 3330 thousand m3. * Data from reference sample Es-3 (Kiipli et al, Guaranteed stone strength mark is 1000 (Korbut et 2000). I.R. – insoluble remnants al, 2010). Carbonate rock of Väo formation does not have a On the Harjumaa schematic map all carbonate rock constant composition (Table2) as well as physical- deposits and working quarries of Middle Ordovician mechanical properties, but it is the best building lay into some kilometres wide zone, where bedrock stone in the Harjumaa County. In Harku deposit, the of Väo Formation is cropping or covered by thin exploration fields number 5 and Naistesoo bedrock layer of soft Quaternary sediments (Fig.2). Only in compressive strength exceed often 150MPa and this formation limestone and dolostone have needed there is guaranteed the strength of stone more than properties for using as building stone. Chemically 1000kg/cm2 (stone mark – 1000). In Harku deposit, this stone is not enough clean for technological in exploration field Karjavälja, Maardu quarry and stone. Harjumaa County is located on the edge of in Valkla deposit carbonate building material is also Fennoscandian Shield, less than 80km is distance to of very high quality, their guaranteed stone mark is Precambrian crystalline metamorphic and magma 800 (Table3). In some places the quality of stone is rock, where during Paleozoic Era was widely going not so good, but the reason may be in secondary processes of weathering and carrying out terrigenous processes as karst, bedrock jointing etc. material. It is the reason why in North Estonian limestone contains different impurities, which in In the map of location Ordovician deposits are chemical analyses are shown as insoluble remains. shown two zones, one belong to Middle and another to Upper Ordovician series (Fig.2).

4 part), Vormsi and Pirgu Stages, while pure micritic Density, Water- limestone are common in the , Nabala 3 Deposit or g/cm ) Stone adsorp- (upper part) and Pirgu (lower part) Stages. The study exploration (volumet- mark tion, % of sedimentation processes indicated that changing part ric mass, (poro- the composition of rocks are caused by alteration of 3 kg/m ) sity %) arid (dry) and humid (wet) periods during the Late Harku, * 2.72-2.74 1.1-2.3 Ordovician (Nestor et al, 2007). 5th part 1000 (3.6-5.5)

Harku, part 2.74-2.82 0.9-1.1 Naistesoo** (2576- 1000 (5.1-7.1) Components in max min average 2645) weight % Harku, part 2.67-2.82 1.5-3.1 Karja- (2534- 800 (4.0-4,6) Block 3, CaO, 55.39 45.25 53.17 Välja**** 2660) Vasalemma 1 Väo *** 2.66 400- 1,3-1,6 600 Block 3,MgO 2.77 0.25 1.09 Jägala*** 2,63 400- 1.4-1.6 500 5.3 0.25 1.2 Sõrve (Ran- 2.66-2.67 600 1.3-1.4 Block 3, In. re. namõisa) Valkla *** 2.6-2.61 800 1.8 Clayey limestone 48.7 38. 7 43.0 Maardu*** 2.61-2.62 800 1.5-1.8 Vasalemma , CaO

Table3. Density, volumetric mass, stone mark, Vasalemma, MgO 6.5 1.6 4.1 water absorption and porosity of Väo Formation carbonate rocks in Harjumaa County. Data from: Vasalemma, In.re. 19.1 8.1 14.5 *Korbut et al, 2010, **Korbut et al, 2005,*** Mõttus, 1978;****Korbut et al, 2007 Table4. Main components contain in Vasalemma Kunda Stage limestone contains many glauconite quarry No 1, block 3 – pure technological grains, Kunda Stage – glauconite and Fe-ooids, also limestone and clayey limestone with impurities kerogenic intercalations and lenses, Aseri Stage – (Mõttus, 1978). In.re. – insoluble remnants Fe-ooids, upper part of Uhaku Stage is clay-rich and The first usable limestone appears in the section of cannot be used as building stone. Local masters are Upper Ordovician in Keila Stage. The lower part of used all of these limestone and dolostone layers. Keila Stage is represented by clayey limestone, it But Väo carbonate rock is strong stone for compressive strength mark does not exceed 400-600. aggregate, good cement raw material, building stone The upper part of Keila Stage and Lower part of for walls and finishing slabs (Perens, Kala, 2007; Oandu Stage is composed by very pure bioclastic Teedumäe, 2007). Upper part of Uhaku Stage and reel limestone, named usually as Vasalemma section may be used for cement production, “marble”. These limestone are really very pure, their At the beginning of the Late Ordovician in the CaO content exceed 53%, sometimes 55% (Table 4). Kukruse Age were formed oil shale deposits in This limestone is used for making lime, in sugar and northeast Estonia. This time sea deepened and into metals production, animal feeds and so on. Clayey sediment was more intensive input of clay material. limestone mostly is used for aggregate production. In Harjumaa County oil shale layers are very thin or Vasalemma “marble” is used as building stone and are absent at all, clayey limestone is too soft for is very nice for inside usage as finishing slabs by it building material. In following Age (Stage) beautiful, light cream colour. Rummu quarry near continued accumulation of clay rich sediments and the Vasalemma quarry is working many years, it this time was intense volcanic activity and from stone is mostly the same. surrounding territories ash reached Estonia and Upper part of Late Ordovician succession, beginning formed many intercalations in the sediments. Only from Keila and Oandu stages forms another building in the second part of Keila Stage the sea became and industrial limestone and dolostone zone in the deeper and lime sand from skeletal debris (detritus) southern part of Harjumaa County (Fig.2). It is started to accumulate in the vicinity of settlement wider than northern Lasnamäe-Uhaku zone, because Vasalemma. It formed after processes of lithification here the clayey limestone alternates with micritic, to coarse-grained, pure limestone of Vasalemma algal limestone and dolostone. Some of part in every Formation. It contains the oldest bioherms (reefs) of stage may be used as construction aggregate or as Estonia. The last part of Upper Ordovician is industrial lime- or dolostone (Perens, Kala, 2007; characterized by the cyclic changing situation of Nestor, 2007; Raukas, Teedumäe, 1997 etc.). For sedimentation, causing alternation of clayey and building stone and finishing slabs may be used Röa pure limestone parts. The higher clay content massive dolostone of Porkuni Stage. characterizes bedrock of Oandu, Nabala (lower half

5 The biggest developed resources of carbonate stone ruumi geoloogiline uuring. Eesti Geoloogiakes- are located in Nabala Stage bedrock, where Saunja kuse aastaraamat 2009. 28-31pp (In Estonian) Formation of aphanitic limestone has thickness 4. Korbut, S., Ramst, R., Peikre, R., 2006. Harju- about 20m. Sporadically limestone is dolomitized. maa Harku lubjakivimaardla Naistesoo uuringu- ruumi geoloogiline uuring. Eesti Geoloogiakes- Conclusion kuse aastaraamat 2005. Tallinn, EGK, 36-39 (in Estonian).. Harjumaa County has large amounts of different 5. Korbu, S., Peikre, R. 2006. Harjumaa Harku carbonate bedrock and developed resources. There lubjakivimaardla Karjavälja I uuringuruumi are two wide zones in county, where all old and geoloogiline uuring (varu seisuga01.01.2006.a). nowadays working quarries are located. In the Eesti Geoloogiakeskuse aastaraamat 2006. stratigraphical section of Ordovician one of them Tallinn: EGK. 34-35pp. (In Estonian). belong to Middle Ordovician, mainly Lasnamäe and 6. Lehtinen, M., Nurmi, P.A., Rämo, O.T. (eds.), Uhaku stages, and another wider zone embraces 2005. Precambrian Geology of Finland – Key to stages from Keila to Porkuni in Upper Ordovician. the Evolution of the Fennoscandian Shield. The northern; Lasnamäe-Uhaku zone has very long Elsevier B.V., Amsterdam. 736pp. history and is represented by very high quality building stones. Many big building in Tallinn are of 7. Mens, K. & Pirrus, E. 1997. Vendian. Cambrian. age more than 700 years and reconstruction is not In: Raukas, A. & Teedumäe, A. Geology and needed. The compressive strength of Väo limestone mineral resources of Estonia. Tallinn: Estonian exceeds often 150 MPa. Academy Publisher, pp.35-52. The southern zone has bigger differences in rock 8. Mõttus, V. 1978. Aruanne ehituskillustikuks types as well in chemical compositions, here may be kõlblike lubjakivi otsimistööde tulemustest met the bedrock of technological purity. Some of Tallinna ümbruses. 142. EGF 3492 (In Estonian). them contain up to 55% CaO or more than 20% 9. Nestor, H., Soesoo, A., Linna, A., Hints, O., MgO. In this zone are extracting stone working Nõlvak, J., 2006. The Ordovician in Estonia and quarries in Rummu and Vasalemma. Only these Southern Finland. MTÜ GEOGuide deposits are giving since technological stone in Baltoscandia, Tallinn. 32pp. Harjumaa. All possibilities are not used and in future 10. Nordkalk. Annual Report 2007. 56pp. natural carbonate stone may take more important place in industry of county. 11. Nordkalk Annual Report 2009. 28pp. 12. Perens, H. 2004.Limetone and dolomites in Acknowledge Estonian building II: Harju, Rapla and Järva counties. Tallinn: Geol. Surv. of Estonia. 144pp The research is supported by Estonian Science (In Estonian). Foundation (ETF 7499) and Doctoral School of 13. Perens, H. & Kala, E. 2007. Limestone – a Energy and Geotechnology II. national stone of Estonia. MTÜ GEOGuide Baltoscandia, Tallinn. 32pp

References 14. Põldvere, A. 2006. Kerguta (565) drill core. 1. Cocks, L.R.M. & Torsvik, H.T., 2005. Baltica Estonian geological sections. Bulletin 7. Geol. from the late Precambrian to mid-Proterozoic Survey of Estonia, Tallinn. 43pp. time: The gain and loss of a terrane’s identity. 15. Raukas, A. & Teedumäe, A. (eds.), 1997. Earth-Science Reviews 72, 39-66. Geology and mineral resources of Estonia. 2. Kiipli, T., Batchelor, R.A., Bernal, J.P. et al., Tallinn: Estonian Academy Publishers. 436pp. 2000. Seven sedimentary rock reference samples 15. Teedumäe, A. 2007. The mineral resources of from Estonia. Oil Shale, 17, 3, 215-223. Estonia: carbonate rocks. In: Põldvere, A. & 3. Korbut, S., Peikre, R., Savitski, L. 2010. Harju- Bauert, H. (eds.). Excursion Guidebook. 15th maa Harku lubjakivimaardla Harku V uuringu- Meeting of MAEGS, Tallinn., pp.10-11.

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