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Burtnieki Stage

ID: 184

General info

Unit nameBurtnieki lade
Unit nameBurtnieki Stage
Belongs toBaltic Middle Devonian
Overlain byGauja Stage
OverliesAruküla Stage
Typechronostratigraphy
RankStage
Scoperegional
Statusformal standard
AuthorGross
Year1940
Age top (Ma)377.00
Age base (Ma)380.50
AgeGivetian
IndexD2BR

Contains

Stratigraphy
Salaca Substage
Abava Substage

Chemical composition and other properties

Variableminavgmaxstdcount
Al2O3 [%]1.800006.0399917.310006.513624
Allogenic minerals (translucent) [%]0.2000024.0799170.4000011.52586224
Amphibole [%]0.200001.9741321.100003.4328858
Anatase [%]0.100000.899995.200000.8803459
Anhydrite [%]0.200004.3000011.600005.174933
Apatite (biogenic) [%]0.100005.0974956.800009.9652245
Apatite [%]0.200006.9734860.000007.84443181
Ba [ppm]0.0170035.77474143.0000061.906524
Barite [%]0.200001.016664.100001.399308
Biotite (brown) [%]0.100005.3276744.800008.46662162
Biotite (green) [%]0.100007.0104076.6000011.53450298
Brucite [%]0.300001.150003.000000.9772416
Calcedon [%]0.300000.442850.900000.206037
CaO [%]0.050000.292850.610000.211777
Carbonates [%]0.200006.0250045.4000011.9919517
Cassiterite [%]0.200000.200000.200000.000001
Chlorite [%]0.100001.7181828.000004.7741334
Corundum [%]0.200000.620001.900000.4777715
Counts [grains]1.00000367.990822174.00000217.69266654
Cu [ppm]1
Epidote/Zoisite [%]0.200001.109254.900001.0583454
Fe-hydroxides [%]0.200007.8421885.3000012.18809211
Fe2O3 [%]0.430001.177502.160000.749644
Fe2O3T [%]0.790001.763333.610001.306423
Fe2O3total [%]0.560001.200002.440000.876963
Feldspars [%]0.600006.3938233.300005.5776981
FeO [%]0.120000.163330.250000.061283
Garnets [%]0.4000012.9721375.1000017.48145201
Glauconite [%]0.200000.488881.200000.3281010
Heavy minerals [%]0.070001.270375.500001.2042653
illiit [%]25.0000064.20588100.0000014.2566368
illiit-smektiit [%]95.0000095.0000095.000000.000001
Insoluble Residue [%]84.1400092.0666697.440005.722013
K2O [%]1.020001.947504.710001.594934
kaoliniit [%]5.0000035.8676475.0000014.0836868
Kyanite [%]0.200002.8660116.900003.25010103
Leucoxene [%]0.400007.4422726.300004.98314220
LOI [%]0.810003.413338.120003.334363
LOI_920 [%]-0.10000-0.09999-0.100000.000001
MgO [%]0.150000.578571.760000.570697
Mica (weathered) [%]0.300000.909992.100000.5430410
Microcline [%]0.200000.643752.600000.5873316
MnO [%]0.008000.016000.021000.004844
Mo [ppm]1.100001.100001.100000.000001
Monazite [%]0.200001.018752.900000.7256164
Muscovite [%]0.100003.9509371.000006.30284321
Nb [ppm]5.600005.600005.600000.000001
Ni [ppm]6.400006.400006.400000.000001
Opaque ore minerals [%]0.8000047.6513380.4000018.43930224
Orthoclase [%]0.600006.9720229.900003.98839143
P2O5 [%]0.037000.046800.066000.010535
Plagioclase [%]0.200000.803572.700000.5756857
Pyrite [%]0.100001.6228516.800003.4156035
Pyroxene [%]0.200001.023523.800000.8073434
Quartz [%]13.3000086.2330399.4000013.18439224
Rutile [%]0.400006.1203718.200003.77186211
S [%]-0.004000.019250.058000.024634
SiO2 [%]63.6300086.9325095.1000013.456154
Size fraction 0.005-0.001 mm [%]11.7000014.4500017.200002.107724
Size fraction 0.01-0.005 mm [%]10.3000014.7875020.800003.204858
Size fraction 0.05-0.01 mm [%]0.200005.4380938.600009.1353884
Size fraction 0.06-0.01 mm [%]0.200001.500007.600001.5791419
Size fraction 0.063-0.05 mm [%]0.300003.5305528.200005.6049936
Size fraction 0.1-0.01 mm [%]2.1000029.1634191.1000024.4036182
Size fraction 0.1-0.05 mm [%]1.4000018.6840970.6000015.5411944
Size fraction 0.1-0.063 mm [%]0.300009.9905867.2000011.0544285
Size fraction 0.105-0.063 mm [%]6.0000032.3125067.0000023.311718
Size fraction 0.16-0.1 mm [%]6.2000021.4750047.5000015.591084
Size fraction 0.16-0.105 mm [%]3.1000018.3999947.4000016.764698
Size fraction 0.2-0.16 mm [%]1.700009.5250018.300006.346804
Size fraction 0.25-0.1 mm [%]0.1000054.2396995.5000026.00881195
Size fraction 0.25-0.16 mm [%]22.9000059.9000073.3000019.219465
Size fraction 0.25-0.2 mm [%]2.2000045.3272778.3000027.4405511
Size fraction 0.28-0.16 mm [%]1.1000024.6749964.9000024.099158
Size fraction 0.315-0.25 mm [%]0.8000010.0749923.100009.423204
Size fraction 0.315-0.28 mm [%]0.100003.3125021.800007.038898
Size fraction 0.4-0.315 mm [%]0.100002.9111110.800004.1013311
Size fraction 0.5-0.25 mm [%]0.1000015.6524884.2000018.71774181
Size fraction 0.5-0.315 mm [%]1.0000010.4428537.8000011.815467
Size fraction 0.5-0.4 mm [%]0.1000012.9700069.2000020.0738116
Size fraction 0.63-0.5 mm [%]0.100000.225000.600000.216504
Size fraction 1.0-0.5 mm [%]0.100003.2021845.100007.24605146
Size fraction 1.0-0.63 mm [%]0.100000.555552.700000.777619
Size fraction 1.6-1.0 mm [%]0.100000.100000.100000.000003
Size fraction 2.0-1.0 mm [%]0.100002.6999919.700004.2688338
Size fraction <0.001 mm [%]11.7000013.5500015.700001.429164
Size fraction <0.005 mm [%]2.1000015.9000040.9000015.472074
Size fraction <0.01 mm [%]0.100006.5333371.900009.70282192
Size fraction >0.5 mm [%]0.100000.166660.200000.047144
Size fraction >1 mm [%]0.100000.619995.400001.0495742
Size fraction >2 mm [%]0.100004.6333315.600005.4361317
Staurolite [%]0.2000010.4004741.100008.15153209
SUM [%]100.00000100.47500100.900000.349104
Th [ppm]2.500002.500002.500000.000001
Ti-minerals (weathered) [%]0.200002.3531211.000002.3820932
TiO2 [%]0.165000.398500.975000.333934
Titanite [%]0.200001.8987810.000001.6493582
Tourmaline [%]0.6000015.41751100.0000013.95482217
U [ppm]-1.70000-1.70000-1.700000.000001
Xenotime [%]0.200000.369230.700000.1538413
Zircon [%]4.5000048.60941100.0000019.89780223
Zn [ppm]8.300008.300008.300000.000001
Zr [ppm]325.00000325.00000325.000000.000001

Specimens in collections (approximately): 2220

Samples in collections (approximately): 359

Thickness map (partial data only)

Localitybase, mtop, mthicknessreferencepreferred
Tsiistre 327 borehole 248.00 157.00 91.00 Kajak, Kalju 1964 0
Värska 6 borehole 84.00 12.00 72.00 Kleesment & Shogenova, 2005 1
Karula 320 borehole 82.20 18.80 63.40 Viiding, Mare 0
Võru (Reedo) borehole 124.00 61.00 63.00 Vingisaar 0
Taagepera borehole 43.00 16.50 26.50 Perens, H 1982 1
Valga 10 borehole 68.00 54.00 14.00 Põldvere, Anne (koost), 2001 1
Mehikoorma 421 borehole 46.90 39.50 7.40 Kleesment 1

Description

Burtnieki Stage

by A. Kleesment & E. Mark-Kurik

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.

As an independent stratigraphical unit the Burtnieki strata was distinguished by Gross (1940b, 1942). Into the rank of regional stage it was raised by Mark-Kurik (Mark 1958). The stratotype is the bank of the Salaca River, 12 km northwest of Lake Burtnieki in northern Latvia. In Estonia, main exposures are situated at Helme and on the banks of the Ahja (Photo 25) and Võhandu rivers. The outcrops of Karksi, Härma, Koorküla and Essi are known as localities of fossil fishes (Fig. 86).

The Burtnieki Stage is spread in southeastern Estonia. The outcrop area forms a 25–50-km-wide belt stretching from Ipiku and Valga in the west to Mehikoorma and Karisilla in the east. The total thickness ranges from 60.6 to 94.5 m (Fig. 86).

The Burtnieki Stage is mainly represented by light (white, yellowish, pinkish and greyish-brown) fine-grained medium- to weakly-cemented cross-bedded sandstones with interlayers of siltstone and clay. The stage lies everywhere above the Tarvastu beds of the Aruküla Stage (Figs. 75, 76, 85). The topmost layer of the Tarvastu beds is, as a rule, represented by reddish or variegated (purplish-grey to reddish-brown) siltstones, which are overlain by white, yellowish-, brownish- or purplish-grey poorly sorted loose sandstones of the Burtnieki Stage.

The Burtnieki Stage is divided into the Salaca (below) and the Abava (above) substages (Table 10). Mark-Kurik (1993a, b) has treated the latter as an independant stage.

Fossils coming from different parts of the Burtnieki Stage, the Härma [hm] and Koorküla [kr] beds and the Abava [ab] Substage belong mainly to fishes: Tartuosteus maximus Mark-Kurik [hm], cephalaspidids [hm], Pycnosteus tuberculatus (Rohon) [hm,kr], Ganosteus stellatus Rohon, Psammosteus bergi (Obr.) [hm], Actinolepis magna Mark-Kurik [hm,ab], Tropinema haermae (Mark) [hm], Homostius latus Asm. [hm,kr], Heterostius ingens Asm. [hm,kr], Coccosteus markae O.Obr. [hm], Asterolepis sp.1 Kar.-Tal.[hm], Homacanthus gracilis (Eichw.) [hm], Nodocosta sp. [kr], Acanthodes? sp. A, Acanthodes? sp. B, Acanthodes? sp. D, Acanthodes sp. [ab], Cheiracanthus brevicostatus Gross [hm,ab], C. longicostatus Gross [hm], Cheiracanthus sp. [ab], Ptychodictyon rimosum Gross [hm], P. sulcatum Gross [hm], ? Ptychodictyon sp. [hm], Diplacanthus carinatus Gross [hm], D. gravis Valiuk. [hm], Acanthodii gen.n. Valiuk. [hm], Markacanthus alius Valiuk. [hm], Rhadinacanthus multisulcatus Valiuk. [hm], Nostolepis sp.n. Valiuk. [hm], Gyroptychius elgae Vorob. [hm], Glyptolepis? karksiensis (Vorob.) [hm], holoptychiids [hm], Psammolepis sp.sp., Byssacanthus sp.sp. [kr,ab], Hamodus lutkevitshi Obr. [kr,ab], Panderichthys? sp. [kr,ab], Psammolepis abavica Mark-Kurik [ab], Psammosteus sp.sp. [ab], Watsonosteus sp.n.? [ab], Livosteus? sp. [ab], Plourdosteus? panderi O. Obr. [ab], Asterolepis essica Lyarsk. [ab], Microbrachius cf. dicki Traq. [ab], Chondrichthyes? [ab], Laccognathus sp. [ab], Osteolepididae [kr, ab], Onychodus? sp. [ab], Dipnoi [ab], Moythomasia? sp. [ab], Cheirolepis sp. [ab] (Sorokin 1981, Valiukevičius 1994, modified).

Of other fossils, silicified wood has been found in the Härma beds and rare lingulates and various remains of the pteridophyte Pseudosporochnus estonicus Kalamees in the upper clayey part of the Abava Substage (Kalamees 1988).

In Estonia and adjacent areas, the Burtnieki Stage is represented by the Burtnieki Formation. On the basis of the lithological and mineralogical data, three cyclic units are distinguished in the Burtnieki Formation. These cycles are observable in all sections of Estonia and defined as the Härma (lower), Koorküla (middle) and Abava (upper) beds (Table 10). Each unit begins with relatively coarse-grained light, variegated (yellowish, pinkish, greyish and brownish) sandstones of a mature mineral composition and ends with clayey silt layers (Figs. 75, 76, 85, Kleesment 1995).

Lithologically and mineralogically (Fig.78), these three beds are rather similar. The sandstones are prevailed by fine-grained fraction which usually forms 50–70% of the rock. The rate of medium-grained and very fine-grained sand fractions is variable, forming 10–30 and 6–20% of the rock, respectively. The share of other fractions rarely exceeds 5%. The predominating thickness of the cross-bedded sandstone series is 20–30 cm. They are dipping to the south, southwest, and southeast. In the Härma beds, the southwest inclination is prevailing, while in the Koorküla and Abava beds the inclination directions are more variable. Siltstones are mostly medium-cemented, variegated, clays are strongly silty, grey, and reddish-brown.

Mineralogically, the rocks of the Burtnieki Formation are predominantly quartzose and feldspatic arenites with the quartz content of 70–90%. Micaceous arenites (content of micas up to 50%) occur as rare thin interbeds. The heavy fraction is dominated by ilmenite (45–65%). The share of allothigenic transparent minerals in the heavy fraction is in general 15–30%. This group is dominated by zircon (40–70%). Of other accessory minerals, tourmaline (7–20%) and staurolite (3–15%) are more important, noteworthy is the appearance of kyanite (Fig. 78). The share of tourmaline is greatest in the Abava beds where it makes up 10-30% of the group of transparent allothigenic minerals.