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Gauja Stage

ID: 185

General info

Unit nameGauja lade
Unit nameGauja Stage
Belongs toBaltic Middle Devonian
Overlain byAmata Stage
OverliesBurtnieki Stage
Typechronostratigraphy
RankStage
Scoperegional
Statusformal standard
AuthorLiepinš
Year1951
Age top (Ma)373.50
Age base (Ma)377.00
AgeGivetian
IndexD2GJ

Lithostratigraphy

Stratigraphy
Gauja Formation
Sietini Member
Lode Member

Stratotypes

TypeLocalityDepth (m)ReferenceRemarks
stratotype (unspecified)Gauya River, LatviaKleesment & Mark-Kurik, 1997

Synonyms and spellings

SynonymLanguageReferenceRemarks
Oredesch-StufeGermanKleesment & Mark-Kurik, 1997

Chemical composition and other properties

Variableminavgmaxstdcount
Al2O3 [%]9.8600013.7600016.080002.774213
Allogenic minerals (translucent) [%]3.4000024.4513060.300009.19491115
Amphibole [%]0.200002.7177717.000003.4650145
Anatase [%]0.200000.921429.100001.6415031
Apatite (biogenic) [%]0.200003.6000017.000005.3641410
Apatite [%]0.200002.8999916.200003.5319046
Ba [ppm]0.029000.047660.059000.013293
Barite [%]0.100000.983334.600001.625236
Biotite (brown) [%]0.100001.8632337.000005.1838272
Biotite (green) [%]0.100004.3726052.000009.28476147
Brucite [%]0.300000.700001.100000.282844
Calcedon [%]0.300000.366660.600000.124729
CaO [%]0.410000.773331.320000.326736
Cassiterite [%]0.200000.500000.800000.300002
Chlorite [%]0.100000.624002.600000.6706825
Corundum [%]0.200000.466660.700000.159866
Counts [grains]22.00000396.927971647.00000221.61924361
Dry density [kg/m3]1961.000002015.500002070.0000054.500002
Epidote/Zoisite [%]0.200001.560866.600001.5982923
Fe-hydroxides [%]0.2000012.2158885.2000017.57471107
Fe2O3 [%]6.760007.060007.360000.300002
Fe2O3T [%]7.150007.936668.510000.575343
Fe2O3total [%]6.920007.200007.480000.280002
Feldspars [%]1.700009.5764728.500007.9055817
FeO [%]0.110000.153330.210000.041893
Garnets [%]0.300005.7000049.300009.3450879
Glauconite [%]0.200000.333330.500000.124723
Gypsum [%]0.300000.300000.300000.000001
Heavy minerals [%]0.140001.220278.350001.6402237
illiit [%]30.0000065.31250100.0000023.5749332
Insoluble Residue [%]81.5000083.1266685.760001.879173
K2O [%]1.720003.090003.880000.972523
kaoliniit [%]5.0000039.6428570.0000020.9458728
Kyanite [%]0.200002.364479.400002.0698176
Leucoxene [%]0.700007.6269928.300005.66194100
LOI [%]4.080005.043335.590000.683243
MgO [%]0.470001.129991.890000.534136
Mica (weathered) [%]0.300000.400000.600000.141423
Microcline [%]0.300000.463630.900000.2143611
MnO [%]0.026000.027660.030000.001693
Monazite [%]0.200001.6689611.800001.6037858
Muscovite [%]0.200003.1812038.800005.78187150
Opaque ore minerals [%]4.4000051.1191375.0000018.55540115
Orthoclase [%]0.600006.2000020.200004.32572116
P2O5 [%]0.079000.168660.336000.118423
Plagioclase [%]0.200000.596002.000000.3736025
Pyrite [%]0.100003.0411716.200004.5692117
Pyroxene [%]0.200003.5909034.000007.1394422
Quartz [%]16.8000088.5977499.4000012.61980133
Rutile [%]1.400006.7817317.500003.32724115
S [%]0.002000.008330.014000.004923
SiO2 [%]61.2800066.5800074.760005.867903
Size fraction 0.005-0.001 mm [%]0.400000.400000.400000.000001
Size fraction 0.01-0.005 mm [%]0.900004.019999.800002.7596310
Size fraction 0.05-0.01 mm [%]0.500001.411113.300000.985959
Size fraction 0.056-0.01 mm [%]0.100000.530432.300000.4629123
Size fraction 0.06-0.01 mm [%]0.100000.888882.200000.5435318
Size fraction 0.063-0.05 mm [%]0.800001.099991.500000.294393
Size fraction 0.075-0.056 mm [%]0.200001.121732.900000.8816723
Size fraction 0.1-0.01 mm [%]4.3000022.2555577.3000019.7675118
Size fraction 0.1-0.05 mm [%]0.9000033.2200087.5000029.9142315
Size fraction 0.1-0.063 mm [%]0.1000017.6446467.5000017.1251156
Size fraction 0.105-0.075 mm [%]0.700006.8999917.600005.3124923
Size fraction 0.15-0.105 mm [%]1.7000015.1478246.6000011.9563223
Size fraction 0.16-0.1 mm [%]8.8000024.7333355.0000021.411733
Size fraction 0.2-0.15 mm [%]8.0000022.9478241.000009.5620523
Size fraction 0.2-0.16 mm [%]7.4000012.9666619.500004.986873
Size fraction 0.25-0.1 mm [%]2.7000059.6447091.8000021.0707085
Size fraction 0.25-0.2 mm [%]5.3000028.4500060.5000021.300884
Size fraction 0.315-0.2 mm [%]12.5000038.3521767.2000015.6250323
Size fraction 0.315-0.25 mm [%]0.7000013.6000021.900009.245893
Size fraction 0.4-0.315 mm [%]0.100006.5666613.200005.349353
Size fraction 0.42-0.315 mm [%]0.5000011.3173932.000008.6499323
Size fraction 0.5-0.25 mm [%]0.2000014.4487159.5000014.9544678
Size fraction 0.5-0.315 mm [%]21.5000021.5000021.500000.000001
Size fraction 0.5-0.4 mm [%]1.800008.7500015.700006.949993
Size fraction 0.6-0.42 mm [%]0.100002.8217310.800002.7684423
Size fraction 0.63-0.5 mm [%]0.500005.5000010.500005.000003
Size fraction 0.85-0.6 mm [%]0.100000.416661.500000.4112923
Size fraction 1.0-0.5 mm [%]0.100002.4948231.200004.9939458
Size fraction 1.0-0.63 mm [%]0.100000.100000.100000.000002
Size fraction 1.6-1.0 mm [%]1
Size fraction 2.0-1.0 mm [%]0.100001.2375010.100002.4707917
Size fraction <0.001 mm [%]2.900002.900002.900000.000001
Size fraction <0.01 mm [%]0.100002.3870948.600005.2991295
Size fraction >0.85 mm [%]0.100000.162500.400000.0927023
Size fraction >1 mm [%]0.200001.771423.600001.436979
Size fraction >2 mm [%]0.100000.479312.100000.4809329
Staurolite [%]0.8000012.9912244.500008.16897114
SUM [%]98.3000099.73333100.600001.020893
Ti-minerals (weathered) [%]0.400002.046515.500001.1670543
TiO2 [%]0.636000.872661.053000.174833
Titanite [%]0.200000.983333.100000.6668731
Tourmaline [%]0.6000018.2304375.0000015.38249115
Xenotime [%]0.200000.516661.000000.2511012
Zircon [%]3.8000051.6587784.9000015.97775114

Specimens in collections (approximately): 283

Samples in collections (approximately): 205

Thickness map (partial data only)

Localitybase, mtop, mthicknessreferencepreferred
Tsiistre 327 borehole 157.00 79.40 77.60 Kajak, Kalju 1964 0
Võru (Reedo) borehole 61.00 35.00 26.00 Vingisaar 0

Description

Gauja 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.

The Gauja Stage was formally established by Liepinš (1951), although the corresponding stratigraphical unit as a Stage already existed in the scheme of Kraus (1934) and had been distinguished by Gross (1942) as “Oredesch-Stufe”. In different periods it has been treated as a separate stage or as the lower part of the Šventoji Stage (Sorokin 1981). The stratotype of the Gauja Stage is the bank of the Gauja River between Cēsis and Sigulda in northern Latvia. In Estonia more important localities are the banks of the Piusa, Pärlijõgi and Mustjõe rivers, Tuhkvitsa Brook and sand quarries near the railway station at Piusa (Fig. 87).

The Gauja Stage is spread in a restricted area in southeastern Estonia. The outcrop area forms a 14–30-km-wide belt which extends from Valga and Luutsniku in the west to Karisilla and Petseri in the east. The total thickness of the stage in Estonia ranges from 78 to 79.8 m (Fig. 87).

The Gauja Stage consists mostly of weakly- to medium-cemented white and light- to yellowish-grey cross-bedded sandstones. It lies everywhere on the topmost clayey-silty complex of the Abava beds of the Burtnieki Stage (Figs. 75, 76, 85). On the contact level the sandstone is often rich in carbonate cement.

The lower and upper parts of the Gauja Stage differ in fossils. The lower, Sietiņi Member has yielded fossil fishes: Psammolepis venyukovi Obr., P. paradoxa Ag., P. heteraster Gross, P.alata Mark-Kurik, Plourdosteus livonicus (Eastm.), Asterolepis ornata Eichw. sensu Ag., Bothriolepis? sp., Glyptolepis baltica Gross, Laccognathus panderi Gross and Megadonichthys kurikae Vorob. in litt. In the Sietiņi Member also some large fragments or stems, or both, of silicified and ferriferous wood have been found (Sorokin 1981, modified).

In the Lode Member, only plant macroremains (Hostinella sp., Archaeopteris sp., A. fissilis Schalh.) and miospores are known. The miospore assemblage includes: Retusotriletes rugulatus Riegel, Samarisporites triangulatus Allen, S. eximius (Allen) Loboziak et Streel, Geminospora micromanifesta (Naumova) Arkh., G. lemurata Balme, emend. Playford, Ancyrospora sp. cf. A. incisa (Naumova) M. Rask. et Obukh., Dictyotriletes sp. cf. Reticulatisporites perlotus (Naumova) Obukh., Perotriletes sp. cf. Rugospora? impolita (Naumova) Tchib. (Blieck et al. 1996).

In Estonia and adjacent areas, the Gauja Stage is represented by the Gauja Formation. In the latter, two cyclic complexes can be distiguished, corresponding to the Sietiņ (lower) and Lode (upper) (Table 10) members, established by Kuršs (1992). The Sietiņi Member consists mostly of sandstones, with variegated siltstone in the topmost part. The lower part of the Lode Member is represented by light, mainly white sandstones, its upper part is dominated by siltstones and clays (Figs. 75, 85).

The sandstones of the Gauja Formation are fine-grained. The share of fine-grained particles is usually 55–65%, the content of very fine-grained particles is 22.5%, on an average. The cross-bedded series are 5–40, mostly 15-30 cm thick, predominately inclined to the southwest, south and southeast. Characteristic are brown iron-rich surfaces, pebbles of purplish-brown and grey clay, quartz and Fe hydroxide.

The siltstones, which form ca 20% of the section on an average, are usually clayey, represented by variegated, grey and brownish varieties. Clays (average 15%) are strongly silty, grey, and purplish-grey, often dolomitic.

Mineralogically, the rocks of the Gauja Formation are predominantly quartzose arenites with the quartz content of 80–94%. The heavy fraction is dominated by ilmenite, transparent allothigenic minerals make up 20–30%. In the latter group, the leading mineral is zircon, although in the Lode Member tourmaline often dominates (Fig. 78). The Sietiņi and Lode members differ notably in the composition of clay minerals. In the Sietiņi Member, the average share of hydromicas is 75% and kaolinite 25%. In the Lode Member, these values are 45 and 55%, respectively. The Lode Member is the most kaolinite-rich level in the Devonian sequence of Estonia.