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Nabala Stage

ID: 36

General info

Unit nameNabala lade
Unit nameNabala Stage
Belongs toKohila Subseries
Overlain byVormsi Stage
OverliesRakvere Stage
Typechronostratigraphy
RankStage
Scoperegional
Statusformal standard
AuthorMännil
Year1958
EtymonNabala, vil. (E)
Age top (Ma)450.80
Age base (Ma)452.00
AgeKatian
Age referenceCooper & Sadler, 2004
IndexFIa
IndexO3NB

Stratotypes

TypeLocalityDepth (m)ReferenceRemarks
holostratotypeNõmmeküla quarry, Harju countyRõõmusoks, 1983
neostratotypeLohu borehole53.00..77.10Rõõmusoks, 1983

Typical rocks

Number: 311-43
Number: 311-47

Chemical composition and other properties

Variableminavgmaxstdcount
Al2O3 [%]0.040001.334738.310001.4203960
Allogenic minerals (translucent) [%]0.400001.100001.800000.700002
Apatite [%]11.1000011.1000011.100000.000001
As [ppm]-2.000002.150006.300004.150002
Ba [ppm]-6.100002.2514146.5000010.8223529
Br [ppm]-1.70000-0.299991.100001.400002
Calcite [%, calculated]0.0000071.4039495.2100024.33056157
CaO [%]4.2000042.8715056.9300011.30194260
Ce [ppm]-15.10000-9.00000-2.900006.100002
Chlorite [%]16.0000016.3999916.800000.399992
Cl [%]0.000000.030790.110000.0242643
Co [ppm]2
CO2 [%]4.0000036.8129745.810008.60976175
Counts [grains]2.00000247.83333500.00000202.008596
Cr [ppm]6.300009.9999915.000002.8648725
Cu [ppm]1.400001.650001.900000.250002
delta13C [‰]-0.360000.886692.080000.62716121
delta18O [‰]-6.82000-4.84642-2.410000.89883109
Dolomite [%, calculated]0.9000010.4884098.0900015.15410157
Dry density [kg/m3]2355.000002602.492062802.0000098.4784063
F [%]-0.02000-0.005000.010000.015002
Fe-hydroxides [%]0.600000.899991.200000.300002
Fe2O3 [%]0.120000.567391.600000.3482250
Fe2O3T [%]0.640001.162852.050000.485207
Fe2O3total [%]0.140000.869303.350000.4886779
Feldspars [%]1.700002.549993.400000.850002
FeO [%]0.010000.183330.840000.1628463
Ga [ppm]0.400001.300002.200000.900002
Garnets [%]11.1000011.1000011.100000.000001
Ge [ppm]2
Glauconite [%]1.6000045.9000073.1000031.595043
Grain density [kg/m3]0.000002680.428572860.00000346.8710363
illiit [%]80.0000083.6666689.000003.036816
Insoluble residue [%, calculated]1.9100013.6594250.8300011.1014552
Insoluble residue [%, calculated]0.1700020.2999990.7900022.66722105
Insoluble residue [%]0.4000010.9058672.1000012.5973587
K2O [%]0.030000.651743.210000.6758960
kloriit [%]10.0000014.6666619.000003.299836
kloriit-smektiit [%]10.0000010.0000010.000000.000001
La [ppm]-19.00000-4.750009.5000014.250002
Leucoxene [%]0.200000.200000.200000.000001
LOI [%]33.2000041.6062046.700002.9957529
LOI920 [%]37.2700039.8950042.520002.625002
MgO [%]0.100004.0230621.460006.01962260
MnO [%]0.000000.092040.570000.1022360
Mo [ppm]2
Na2O [%]0.000000.067670.380000.0688350
Nb [ppm]1.800002.250002.700000.450002
Nd [ppm]-13.10000-4.300004.500008.800002
Ni [ppm]0.500002.600004.700002.100002
Opaque ore minerals [%]0.400000.600000.800000.200002
P-wave velocity [m/sec in dry sample]2800.000004742.142855897.00000629.5802242
P-wave velocity [m/sec in wet sample]2304.000004892.546736135.00000720.2445352
P2O5 [%]0.000000.065360.515270.0968860
Pb [ppm]4.000004.150004.300000.150002
Porosity [%]1.270004.3656415.100002.8168962
Pyrite [%]96.4000096.5000096.600000.099992
Quartz [%]9.2000013.0000016.800003.800002
Rb [ppm]2.2000011.9500021.700009.750002
S [%]0.010000.106651.710000.2518743
Se [ppm]2
SiO2 [%]0.150005.5178329.850005.4429960
Size fraction 0.01-0.002 mm [%]26.6200036.4812447.170005.4660916
Size fraction 0.05-0.01 mm [%]3.4000012.2805025.940006.6717420
Size fraction 0.1-0.05 mm [%]0.100008.6006239.090009.3178518
Size fraction 0.25-0.1 mm [%]0.100002.199994.300002.099993
Size fraction 0.5-0.25 mm [%]2.000002.000002.000000.000003
Size fraction 1-0.5 mm [%]1
Size fraction <0.002 mm [%]19.8000041.7737553.780009.0250816
Size fraction <0.01 mm [%]69.8000089.5750096.5000011.420894
Size fraction >1 mm [%]1
Sr [ppm]152.00000214.30000276.6000062.300002
SUM [%]96.5086499.32994100.000001.0006727
Th [ppm]0.300000.900001.500000.600002
TiO2 [%]0.000000.062460.440000.0720260
U [ppm]0.600001.500002.400000.899992
V [ppm]0.002004.6780025.600007.4825425
W [ppm]4.0000013.1111122.000006.2971610
Wet density [kg/m3]2449.000002650.492062817.0000080.4917163
Y [ppm]2.900004.099995.300001.200002
Zircon [%]77.8000088.90000100.0000011.099992
Zn [ppm]3.100008.3166622.000004.7495312
Zr [ppm]9.2000016.5499923.900007.350002

Specimens in collections (approximately): 2523

Samples in collections (approximately): 1410

Thickness map (partial data only)

Localitybase, mtop, mthicknessreferencepreferred
Puhmu 567 borehole 122.00 91.00 31.00 Saadre 0
Soovälja K-1 borehole 105.10 78.40 26.70 Põldvere, Anne (koost), 2002 2002 1
Kerguta 565 borehole 106.80 80.80 26.00 Põldvere, Anne (koost), 2006 Põldvere, Anne Estonian Geological Sections Bulletin 7 2006 1
Viki borehole 323.60 300.60 23.00 Põldvere, Anne (koost), 2010 1
Karula 320 borehole 394.00 373.30 20.70 0
Kingissepa GI borehole 362.80 342.40 20.40 Põlma 0
Mehikoorma 421 borehole 283.40 265.80 17.60 Põldvere, Anne 1
Rapla borehole 108.25 92.60 15.65 Põlma, 1972b Põlma 1972 1
Võru (Reedo) borehole 381.60 366.00 15.60 Vingisaar 0
Eikla 508 borehole 290.30 275.40 14.90 Kala et al., 1967 1
Kahala II borehole 145.10 130.70 14.40 Kala et al., 1967 0
Kaleste F-356 borehole 50.80 36.60 14.20 Suuroja, Kalle 1991 1
Taga-Roostoja 25 borehole 23.70 10.50 13.20 Põldvere 1997 0
Ohesaare borehole 462.65 449.50 13.15 Põlma 1
Priekule 20 borehole 1416.20 1404.20 12.00 Põlma, päevik 19 0
Kassari F-371 borehole 101.20 89.20 12.00 Suuroja, Kalle 1988 1
Äiamaa borehole 162.70 150.95 11.75 Põlma 0
Männamaa F-367 borehole 115.30 104.00 11.30 Põldvere, Anne (koost), 2008a 1
Põlva 423 borehole 346.00 335.40 10.60 Kajak 0
Alatskivi 422 borehole 164.00 153.40 10.60 Kajak 1974 1
Sõru 400 borehole 150.40 140.00 10.40 Kala, E., Kajak, K. & Kajak, H. (kompleksne geoloogiline kaardistamine 1:200 000) 1971 1
Aidu 427 borehole 198.00 187.90 10.10 Meidla, 1996a 1
Orjaku borehole 105.90 96.00 9.90 Meidla, 1996a Meidla 1
Orjaku borehole 105.90 96.00 9.90 Meidla, 1996a 1
Põltsamaa H-163 borehole 201.90 192.40 9.50 Põlma 1984 1
Laeva 13 borehole 212.20 202.80 9.40 1
Apraksin Bor 17 borehole, Leningrad Oblast 84.40 75.20 9.20 Põlma 1984 1
Võhma borehole, Viljandi County 214.50 205.55 8.95 Põlma 0
Velise V-97 borehole 149.80 141.00 8.80 Suuroja, Kalle 1991 1
Otepää 2 borehole 431.00 422.30 8.70 Sarv 1
Virtsu 360 borehole 198.60 190.10 8.50 Meidla, 1996a 1
Kaagvere 1 borehole 254.45 246.30 8.15 Meidla, 1996a 1
Valga 10 borehole 373.50 365.70 7.80 Põldvere, Anne (koost), 2001 1
Häädemeeste 172 borehole 455.70 450.80 4.90 Kajak 1969 1
Viljandi 91 borehole 322.30 317.75 4.55 Kajak 1969 0
Ruhnu 500 borehole 636.00 631.80 4.20 Põldvere, Anne (koost), 2003 1
Abja 92 borehole 396.90 392.90 4.00 Kajak 1969 1
Tartu 453 borehole 286.50 282.60 3.90 Põldvere, Anne et al., 1998 1
Laeva 18 borehole 227.60 224.00 3.60 Nestor, H., päevik 23 0
Are 171 borehole 256.20 252.70 3.50 Kajak 1969 0
Muhu 590 borehole 202.10 202.10 0.00 Perens, H 0
Pärnu 6 borehole 313.90 320.10 -6.20 1

Description

Nabala Stage

L. Hints & T. Meidla

Original text from: Raukas, A., Teedumäe, A. (eds). 1997. Geology and Mineral Resources of Estonia. Estonian Academy Publishers, Tallinn. 436 pp. ISBN 9985-50-185-3. Available online at: sarv.gi.ee/geology.

The Nabala Stage was distinguished by Männil (1958b) as the lower part of the Schmidt’s (1858) “Lyckholm’sche Schicht”. He subdivided the stage into the lower, Paekna and the upper, Saunja substages (see also Öpik & Laasi 1937, Jaanusson 1994). Nowadays they are used as lithostratigraphical units (formations) which represent the Nabala Stage with a total thickness of 10 to 35 m in northern and partly in central Estonia (Fig. 53). The Paekna Formation is up to 16 m thick and comprises predominantly argillaceous bioclastic limestones intercalating with micritic limestones. The thickness of micritic interlayers is usually about 0.1 m, but occasionally it may reach 1-3 m. The up-to-28-m-thick micritic limestones of the Saunja Formation are lithologically uniform and occur all over Estonia. Their thickness decreases towards the south until it is only 0.3 m (Meidla 1996). South of the Muhu - Mustvee line, the lower Paekna Formation is replaced by the Mõntu Formation. This 3–7-m-thick complex consists of argillaceous bioclastic limestones with rare thin (5–30 cm) layers of micritic limestones containing glauconite (Oraspõld 1995).

On the transition from the Rakvere to the Nabala Stage the shelly fauna undergoes notable renovation. Of about 150 species and subspecies occurring in the Nabala Stage, only one third is common with the Rakvere Stage (Männil et al. 1966). Several new species of brachiopods, including Bekkeromena semipartita (Roemer), Ilmarinia sinuata (Pahlen), Laticrura rostrata Hints, Sulevorthis lyckholmiensis (Wysogorski), Pseudolingula quadrata (Eichwald), appear in the Nabala Stage. Some of these species are missing in the Saunja Formation, but appear again in the overlying Vormsi Stage. The micritic limestones of the Saunja Formation contain a notably abundant and diverse fauna of molluscs (about 30 gastropod and more than 10 cephalopod species).

The lower boundary of the stage is exposed only in the Paekna quarry (Nõlvak & Meidla 1990). It is marked by a series of uneven discontinuity surfaces, above which there appears a new association of chitinozoans, including the zonal Armoricochitina reticulifera (Grahn). The latter can be used as the most reliable fossil for the identification of the lower boundary of the Nabala Stage in the core sections in central and southern Estonia.

The composition of ostracodes changes remarkably on the Rakvere - Nabala transition. Several new taxa, including Disulcina perita explicata Sarv, Tetrada neckajae Meidla, Oepikella luminosa Sarv a.o., appear in the lower part of the Nabala Stage, but mainly somewhat higher of the lower boundary of the Paekna Formation (Fig. 50). For this reason the lower boundary of the stage is marked better in the ostracode record by the disappearance of the species Disulcina perita perita (Sarv) and Daleiella admiranda Meidla (a zonal species) in the uppermost part of the Rakvere Stage (Meidla 1996). Brachiopods are found mostly in the lower Paekna Formation and among them new faunal elements Pseudolingula quadrata (Eichwald) and Sulevorthis lyckholmiensis (Wysogorski) appear close to the lower boundary of the Nabala Stage (Fig. 54).

The Nabala Stage corresponds to the middle part of the Pleurogratus linearis graptolite Zone (Table 7) and the upper part of the North Atlantic superbus conodont Zone. In the ostracode record, the summary differences between the Paekna and Saunja formations are not significant, but the very uneven distribution of ostracodes in the Saunja Formation should be mentioned (Meidla 1996).