Adavere Stage
General info
Belongs to
Type chronostratigraphy
Rank Stage
Scope regional
Status formal standard
Author Twenhofel
Year 1916
Etymon Adavere set. (E)
Original locality quarry at Adavere
Age top (Ma) 428.2
Age base (Ma) 436.7
Age (Ma)
Age reference Melchin et al., 2004
Index
H
Alt. index
S1AD
Date changed 2014-11-28
Stratotypes
LocalityTypeFrom (m)1To (m)2ReferenceRemarks
Adavere quarry
holostratotype
Twenhofel, 1916 hävinud
Päri quarry
neostratotype
Nestor, H., 1993a
Kirikuküla borehole
hypostratotype
350.3 Nestor, H., 1993a
IDSample No.LocalityDepth / thickness (m)StratigraphyCollectorDate collectedImage
204138 204138 Enge River near Vängla bridge Adavere Stage Tammekänd, Mairy
204137 204137 Enge River near Vängla bridge Adavere Stage Tammekänd, Mairy
204136 204136 Valgu trench outcrops Adavere Stage Tammekänd, Mairy
204135 204135 Päri quarry Adavere Stage Tammekänd, Mairy
204134 204134 Päri quarry Adavere Stage Tammekänd, Mairy
204133 204133 Päri quarry Adavere Stage Tammekänd, Mairy
204132 204132 Valgu trench outcrops Adavere Stage Tammekänd, Mairy
190117 CM-1378 Kaugatuma 509 borehole 274.4 Adavere Stage Männik, Peep
190116 CM-1379 Kaugatuma 509 borehole 272.4 Adavere Stage Männik, Peep
190115 CM-1380 Kaugatuma 509 borehole 271.8 Adavere Stage Männik, Peep
190114 CM-1381 Kaugatuma 509 borehole 271 Adavere Stage Männik, Peep
190113 CM-1382 Kaugatuma 509 borehole 270 Adavere Stage Männik, Peep
190112 CM-1383 Kaugatuma 509 borehole 268.95 Adavere Stage Männik, Peep
190111 CM-1384 Kaugatuma 509 borehole 268.55 Adavere Stage Männik, Peep
190110 CM-1385 Kaugatuma 509 borehole 267.6 Adavere Stage Männik, Peep
190109 CM-1386 Kaugatuma 509 borehole 267.1 Adavere Stage Männik, Peep
190108 CM-1387 Kaugatuma 509 borehole 266.3 Adavere Stage Männik, Peep
190107 CM-1388 Kaugatuma 509 borehole 264.02 Adavere Stage Männik, Peep
190106 CM-1389 Kaugatuma 509 borehole 263.8 Adavere Stage Männik, Peep
190105 190105 Kaugatuma 509 borehole 263.2 Adavere Stage Männik, Peep
190104 CM-1390 Kaugatuma 509 borehole 262.6 Adavere Stage Männik, Peep
190103 CM-1393 Kaugatuma 509 borehole 261.6 Adavere Stage Männik, Peep
190102 CM-1391 Kaugatuma 509 borehole 259.4 Adavere Stage Männik, Peep
190101 CM-1392 Kaugatuma 509 borehole 258.2 Adavere Stage Männik, Peep
190100 CM-1394 Kaugatuma 509 borehole 255.7 Adavere Stage Männik, Peep
Description

Adavere 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 Adavere Stage as a stratigraphical unit was established by Schmidt (1858) as the uppermost unit (zone 6) of the group of smooth pentamerids (“Gruppe der glatten Pentameren”). Afterwards it was termed the Esthonus-Schicht (Schmidt 1881), Addifer Formation (Twenhofel 1916), Adavere Stage (Bekker 1922). Kaljo (1962) fitted the upper boundary of the stage with the Llandovery and Wenlock boundary and included in it the marlstones of the present Velise Formation. Recently, Perens (1992) and Nestor (1995a) excluded the Mõhküla beds and replaced them into the Raikküla Stage.

The Päri quarry in western Estonia has been selected as the neostratotype of the stage (Nestor 1993, 1995a) and the Kirikuküla core at the depth of 50.3 m may be treated as the boundary stratotype of the stage. The Adavere Stage is distributed in the southernmost part of Hiiumaa Island, on Saaremaa and Muhu islands and in the southwestern part of mainland Estonia as far as the Viljandi fault. The outcrop extends as a 10—15-km-wide belt from the southernmost Hiiumaa Island and the Soela Strait over Matsalu Bay up to the vicinity of Türi - Vändra being denudated eastwards the Paide-Pärnu belt of disturbances. The main localities are the Saastna coast, Päri quarry, river banks at Päärdu, Jädivere, Velise, Valgu, Vändra and ditches at Lätiküla and Valgu (Fig. 67). The thickness of the stage increases westwards — from 10.7 m in the Ristiküla borehole to 56.3 m at Nässumaa.

The Adavere Stage is represented by thin-bedded to nodular biomicritic limestones (wackestones to packstones) with Pentamerus oblongus (below) and marl- to mudstones (above). The former unit is treated as the Rumba Formation and the latter as the Velise Formation. The clay content increases westwards. The lower boundary of the stage coincides with the strongly pyritized erosion surface at the base of the nodular biomicritic limestones of the Rumba Formation, transgressively overlying different strata of the Raikküla Stage. The Adavere Stage contains rather rich shelly fauna of Pentamerus (below) and Clorinda (above) communities. Microfossils (chitinozoans, ostracodes, conodonts) are more frequent in the mud- and marlstones of the Velise Formation, almost devoid of corals and stromatoporoids. The most characteristic species are as follows (abbreviations in brackets: rm - Rumba Formation, vl - Velise Formation): Clathrodictyon variolare (Rosen) (rm), Mesofavosites obliquus Sokolov (rm), Angopora hisingeri (Jones) (vl), Palaeocyclus porpita (Linnaeus) (vl), Prodarwinia speciosa (Dybowski) (rm), Pentamerus oblongus (Sowerby) (rm), Stricklandia laevis (Sowerby) (rm), Dicoelosia baltica Musteikis et Puura (vl), Encrinurus (Nucleurus) rumbaensis Rosenstein (rm), Calymene frontosa Lindström (vl), Beirichia valguensis Sarv (rm), Longiscella caudalis (Jones) (vl), Conochitina emmastensis Nestor (rm), Eisenackitina dolioliformis Umnova (rm, vl), Angochitina longicollis Eisenack (vl), Pterospathodus celloni Walliser (vl), P. amorphognathoides Walliser (vl), Spirograptus turriculatus (Barrande) (vl), Monograptus discus Törnquist (vl), Monoclimacis griestoniensis (Nicol) (vl).

The presence of the index species of graptolites (S. turriculatus, M. griestoniensis) and conodonts (P. celloni, P. amorphognathoides) in the upper half of the Adavere Stage demonstrates that most probably the stage corresponds to the Monograptus sedgwickii to Monoclimacis crenulata biozones.

In Estonia, the Adavere Stage consists of the Rumba (below) and Velise (above) formations. The Rumba Formation spreads on the islands of the West-Estonian Archipelago and in the southwestern part of mainland Estonia. It is represented by horizontally-bedded to nodular biomicritic limestones (wackestones, packstones) with clayey partings and scattered shells or tempestitic accumulations of the brachiopod Pentamerus oblongus. The formation consists of twelve low-grade sedimentary cycles beginning with argillaceous rocks (marlstones, argillaceous limestones) and ending with a layer of pure, hard limestone (Einasto et al. 1972). Westwards the clay content of the rocks increases and on Saaremaa Island marlstones are prevailing in the sequence of the Rumba Formation. A characteristic yellowish-green tuffaceous (metabentonite) interlayer (8 to 18 cm) occurs at the level of the base of the upper third of the sequence.

The thickness of the Rumba Formation is mostly 15 to 19 m and it decreases at the western and eastern margins of the distribution area. Local hiatuses occur in the Ohesaare and Are sections.

The Velise Formation overlies the Rumba Formation and consists of different marlstones and mudstones up to plastic clays. The mostly greenish- to bluish-grey rocks are south- and eastwards replaced by red-coloured (purple) varieties. In the southwesternmost sections (Ohesaare, Ruhnu) graptolites are present in the dark-grey interlayers of argillite. Thin (0.5 to 5.0 cm) metabentonite interlayers are characteristic to the formation. The thickness of the formation is greatest in northwestern Saaremaa, reaching 37 - 38 m in the Viki and Eikla sections. In the southeast direction, it decreases until thinning out in the Ristiküla section, eastern Pärnumaa.