Paala Formation
General info
Belongs to
Type lithostratigraphy
Rank Formation
Original rank Paala Beds
Scope regional
Status formal standard
Author Mens & Pirrus
Etymon Paala, place in Viljandi town, southern Estonia
Age (Ma)
Index
Cm3pl
Alt. index
Ca2pl
Alt. index
Ꞓ2pl
Date added 2012-10-16
Date changed 2022-11-21
Stratotypes
LocalityTypeFrom (m)1To (m)2ReferenceRemarks
Viljandi * borehole
holostratotype
409.8434 Mens et al., 1984
NumberNameLocalityDepth (m)StratigraphyImage
GIT 417-1293 Siltstone Äiamaa borehole 261.04 Middle Cambrian (old nomenclature)
GIT 417-1292 Siltstone Äiamaa borehole 255.28 Middle Cambrian (old nomenclature)
GIT 417-1291 Siltstone Äiamaa borehole 250.1 Middle Cambrian (old nomenclature)
GIT 418-10 sedimentary rocks Aluksne 99 borehole 1068 Cambrian
GIT 418-9 Sandstone Aluksne 99 borehole 1072 Cambrian
GIT 418-8 Sandstone Aluksne 99 borehole 1080 Cambrian
GIT 418-7 sedimentary rocks Aluksne 99 borehole 1089.5 Cambrian
GIT 417-1246 Siltstone Petseri 330 borehole 483.3 Middle Cambrian (old nomenclature)
GIT 417-1245 Sandstone Petseri 330 borehole 482.1 Middle Cambrian (old nomenclature)
GIT 417-1244 Sandstone Petseri 330 borehole 479.5 Middle Cambrian (old nomenclature)
GIT 417-1243 Sandstone Petseri 330 borehole 473.5 Middle Cambrian (old nomenclature)
GIT 417-1242 Sandstone Petseri 330 borehole 468 Middle Cambrian (old nomenclature)
GIT 417-1241 Sandstone Petseri 330 borehole 463.7 Middle Cambrian (old nomenclature)
GIT 417-1240 Siltstone Petseri 330 borehole 460 Upper Cambrian (old nomenclature)
GIT 417-1176 sedimentary rocks Vaki 67 borehole 279 Middle Cambrian (old nomenclature)
GIT 417-1175 sedimentary rocks Vaki 67 borehole 274.6 Middle Cambrian (old nomenclature)
GIT 417-775 sedimentary rocks Põlva 423 borehole 451 Lower Cambrian (old nomenclature)
GIT 417-774 sedimentary rocks Põlva 423 borehole 449.7 Lower Cambrian (old nomenclature)
GIT 417-628 sedimentary rocks Viljandi 91 borehole 410.1 Lower Cambrian (old nomenclature)
GIT 417-627 sedimentary rocks Viljandi 91 borehole 416.8 Lower Cambrian (old nomenclature)
GIT 417-626 sedimentary rocks Viljandi 91 borehole 434.5 Lower Cambrian (old nomenclature)
GIT 417-582 sedimentary rocks Äiamaa borehole 250.8 Middle Cambrian (old nomenclature)
GIT 417-579 Siltstone Äiamaa borehole 259.3 Middle Cambrian (old nomenclature)
GIT 414-209 sedimentary rocks Laeva 8 borehole 306.8 Middle Cambrian (old nomenclature)
GIT 414-163 sedimentary rocks Põlva 423 borehole 488.9 Middle Cambrian (old nomenclature)
Description

Mens, K. & Pirrus, E. (1997). Cambrian. In: Raukas, A., Teedumäe, A. (eds). Geology and Mineral Resources of Estonia. Estonian Academy Publishers, Tallinn. 436 pp. ISBN 9985-50-185-3. 

The Paala Formation occurs in central and southeastern Estonia transgressively on the crystalline basement or on the Lower Cambrian rocks the type section is the Viljandi drill core (Fig. 22-203) in the interval of 409.8 to 434 m (Mens et al. 1984). The thickness of the formation varies greatly. Due to the low core yield, the determination of the boundaries is complicated and the thickness of the formation is unclear.

The formation consists of light quartzose non‑glauconitic middle‑ to fine‑grained sandstones with pellets of white kaolinitic clay. The grain-size of the rocks in the lower and upper parts of the formation is coarser than in its middle part where very fine- to fine‑grained varieties dominate. Feldspar and muscovite are not common. The heavy mineral assemblage is mainly composed of allothigenic minerals dominated by ilmenite. In the group of heavy transparent minerals, zircon is always the index mineral.

The character of the basal bed depends on the type of underlying rocks. On the crystalline basement, it consists of conglomeratic sandstone, locally with phosphatized pebbles (Laanemetsa, Fig. 22-269). Resting upon the argillaceous Lower Cambrian rocks, which are often weathered, the basal bed occurs like a variegated kaolinitic clay comprising coarse grains of quartz redeposited from the weathering crust.