Raikküla Stage
General info
Belongs to
Type chronostratigraphy
Rank Stage
Scope regional
Status formal standard
Author Schmidt
Year 1881
Etymon Raikküla set. (E)
Original locality Raikküla-Paka scarp+core
Age top (Ma) 436.7
Age base (Ma) 441
Age (Ma)
Age reference Melchin et al., 2004
Alt. index
Date changed 2014-11-28
LocalityTypeFrom (m)1To (m)2ReferenceRemarks
Raikküla H-138 borehole
0.535 Nestor, H., 1987a Raikküla-Paka scrap + core, Keila dep.
Raikküla Paka terrace
Nestor, H., 1987a
IDSample No.LocalityDepth / thickness (m)StratigraphyCollectorDate collectedImage
204212 204212 Kalana Quarry Raikküla Stage Toom, Ursula 2012-09-10
204172 204172 Kalana Quarry Raikküla Stage Hints, Olle 2023-06-14
190216 RE-177 Ungru karjäär Raikküla Stage Einasto, Rein
190215 RE-176 Ungru karjäär Raikküla Stage Einasto, Rein
190214 RE-175 Ungru karjäär Raikküla Stage Einasto, Rein
190213 RE-174 Ungru karjäär Raikküla Stage Einasto, Rein
190212 RE-173 Ungru karjäär Raikküla Stage Einasto, Rein
190211 RE-172 Ungru karjäär Raikküla Stage Einasto, Rein
190210 RE-171 Ungru karjäär Raikküla Stage Einasto, Rein
190209 RE-170 Ungru karjäär Raikküla Stage Einasto, Rein
190197 RE-158 Kalana Quarry Raikküla Stage Einasto, Rein
190118 190118 Kaugatuma 509 borehole 317.05 Raikküla Stage Nõlvak, Jaak
189123 189123 Heimtali 422 borehole 160.3 Raikküla Stage
189122 189122 Heimtali 422 borehole 158.3 Raikküla Stage
189121 189121 Heimtali 422 borehole 156.3 Raikküla Stage
189120 189120 Heimtali 422 borehole 154.3 Raikküla Stage
189119 189119 Heimtali 422 borehole 152.3 Raikküla Stage
189118 189118 Heimtali 422 borehole 150.3 Raikküla Stage
189117 189117 Heimtali 422 borehole 148.3 Raikküla Stage
189116 189116 Heimtali 422 borehole 146.3 Raikküla Stage
189115 189115 Heimtali 422 borehole 144.3 Raikküla Stage
189114 189114 Heimtali 422 borehole 141.1 Raikküla Stage
189113 189113 Heimtali 422 borehole 141 Raikküla Stage
189112 189112 Heimtali 422 borehole 138 Raikküla Stage
189111 189111 Heimtali 422 borehole 137.1 Raikküla Stage

Raikküla Stage

by H. Nestor

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 Raikküla beds were originally defined (Schmidt 1858) as the “Intermediate zone” (Zwischenzone) between the strata with Pentamerus borealis and P. oblongus. In 1881, Schmidt introduced the geographical name - Raikküllsche Schicht. Kaljo and Vingisaar (1969) presented the currently used subdivision of the stage for southern Estonia. Perens (1992) and H. Nestor (1995a) modernized the classification for the outcrop area. The Mõhküla beds, earlier attributed to the Adavere Stage, were replaced into the Raikküla Stage as they are separated from the rest of the Adavere Stage by a structural disconformity (Nestor 1995a). However, since the stratigraphical level of the Mõhküla beds was changed only recently, it is not yet reflected in the limit between the outcrops of the Raikküla and Adavere stages on the printed geological maps.

The Raikküla-Paka scarp and Raikküla drill core in the interval of 0.5 to 35.0 m have been defined as the composite stratotype of the stage (Nestor 1993). The Raikküla Stage is distributed on the islands of the West-Estonian Archipelago and in the western, central and southern parts of mainland Estonia. The outcrop extends as a latitudinal, eastward widening belt (6 to 45 km) from southern Hiiumaa as far as the southeastern slope of the Pandivere Upland near Palamuse. The main localities are active or abandoned quarries at Pusku, Orgita, Keava, Mündi, Kalana and Rôstla, and ancient coastal scarps (inland cliffs) at Pakamägi and Raikküla-Paka. The thickness of the stage varies from 16.3 m in the Murika borehole to 176.3 m in the Ikla borehole (Fig. 66) and decreases abruptly in the northwest direction due to the end-Raikküla denudation of the upper layers of rocks.

The Raikküla Stage consists of a variety of carbonate rocks. The most characteristic are micritic (micro- and cryptocrystalline) limestones cyclically interbedding with marl- or mudstones in the south and with different bioclastic limestones (wacke-, pack- and grainstones) in the north. In the northernmost sections of central Estonia, the shallowing-up sedimentary cycles may end with argillaceous primary dolomites. In the southernmost sections, the marl- and mudstones contain graptolites on certain levels. In central Estonia, in the Paide - Pärnu belt of faults and eastwards, the Raikküla rocks are strongly dolomitized.

The lower boundary of the stage coincides with the base of a band of marl- or mudstones overlain by thick deposit of monotonous micritic limestones of the Järva-Jaani beds in the north and Slitere Member in the south. In the area of distribution of the most shallow-water sequences of the Hilliste and Raikküla formations the boundary is less definite. Above the boundary, sparse graptolites of the Pristiograptus cyphus Biozone and chitinozoans of the Conochitina electa Biozone (C. electa, C. maennili, etc.) appear.

Fossils are of uneven distribution in the rocks of the Raikküla Stage. The widespread micritic limestones and different dolostones (from pure dolomite to dolomitic marl) contain occasional macrofossils. The most characteristic species are (abbreviations in brackets: rk - Raikküla Formation, nr - Nurmekund Formation, sr - Saarde Formation, u.pt. - upper part, m.pt. - middle part, l.pt. - lower part): Clathrodictyon clivosum Nestor (rk, u. pt.), Parastriatopora celebrata Klaamann (rk, u. pt.), Borealis pumilus (Eichwald) (nr), Borealis borealis osloensis Mjork (nr), Meifodia ovalis Williams (sr), Hermannina hisingeri (Schmidt) (rk, nr), Bythrocyproidea sarvi Neckaja (nr), Icriognathus cornutus Männik (rk, l. pt.), Kockelella manitoulinensis (Pollack, Rexroad et Mehl), (rk, nr), Conochitina electa Nestor (rk, nr, sr, l. pt.), C. iklaensis Nestor (nr, sr), Spinachitina maennili Nestor (sr), Coronograptus cyphus (Lapworth) (sr, l. pt.), C. gregarius (Lapworth) (nr, sr, m. pt.), Demirastrites triangulatus (Harkness) (sr, m. pt.), D. convolutus (Hisinger) (sr, u. pt.). The presence of zonal graptolites shows that the Raikküla Stage spans from the C. cyphus Biozone to the D. convolutus Biozone.

The Raikküla Stage consists of the Raikküla, Nurmekund and Saarde formations, laterally replacing each other from north to south (Figs. 64, 65). The upper part of the Hilliste Formation is of Raikküla Age (Table 8).

The Raikküla Formation is distributed in central and western Estonia, in the Lääne, Rapla and Järva counties. It is represented by two shallowing-up sedimentation cycles star-ting with biomicritic or micritic limestones, succeeded by ske-letal grainstones, pelletal or coral-stromatoporoid limestones, and ending with argillaceous lagoonal dolostones. These cycles are treated as the lower and upper subformations (Nestor 1995a). The thickness of the formation varies from 30 m in the Kiideva borehole to 56 m in the Käru borehole. The upper layers of the formation have undergone considerable denudation and in the westernmost sections of mainland Estonia the upper subformation thins totally out.

The Nurmekund Formation south and east of the Raikküla Formation consists of five sedimentary cycles which begin with a relatively thin layer of marlstone or argillaceous limestone. The main, middle part of the cycle is represented by wavy-bedded micritic limestone, the upper part by bioclastic limestones containing numerous discontinuity surfaces. In central Estonia, the formation is strongly dolomitized, particularly its upper half. The first, third and fifth cycles from below are thicker and more complete, the second and fourth being thinner and less typical. In ascending order, the cycles are termed the Järva-Jaani, Vändra, Jõgeva, Imavere and Mõhküla beds (Table 8). Westwards the upper beds gradually thin out and on Saaremaa Island only the Järva-Jaani and, partly, the Vändra beds are present. The thickness of the formation ranges from 16 m in the Murika borehole to 73+ m in the Võhma borehole.

The Saarde Formation is distributed in southwestern Estonia. It consists of cyclically alternating deposits of horizontally-bedded micritic lime- and marlstones or mudstones and is subdivided into six members. The lowermost, rather thin mudstone member, comprised mostly of argillites, has no name and was earlier included in the Õhne Formation of the Juuru Stage. In ascending order, the Slītere, Kolka, Ikla, Lemme and Staicele members follow. The shaly mudstone interlayers in the Ikla Member abound in graptolites of the Demirastrites triangulatus Zone. In other members graptolites are less frequent. In its full thickness (176.3 m) the Saarde Formation occurs only in the Ikla borehole.