|
Summary Vaiguva Valsčius subsurface setup
Aleksandras Šliaupa
The area of the former Vaiguva Valsčius is sandwiched among the Central Žemaitija hill area and two plateaus: North-east Žemaitija and East Žemaitija. Therefore, the relief and the geological face of the surface are rather varying, as well as the subsurface setup that has been explored by core sampling and geophysical methods. Two stages are distinguished in the developmental history of the subsurface: a very long (billions of years) geological epoch, when the crystalline, magmatic and metamorphic rocks were forming, and the stage when the sedimentary cover was being settled. The latter stage lasted just about 700 million years, when the 18001900 metre thick layer of sedimentary deposits was formed. The crystalline rocks make more than 40 km thick Earths crust. Magmatic and metamorphic rocks, due to their variety and
structure conditions, are grouped into separate blocks or zones. Thus the
environs of Vaiguva lie at the eastern margin of the West Lithuanian
granulitic domain (block), where TauragėOgrė, Telšiai, MažeikiaiVilnius
and Jurbarkas zones are distinguished. The sedimentary cover consists of
Cambrian, Ordovician, Silurian, Devonian, Upper Permian, Lower Triassic,
MiddleUpper Jurassic, Lower Cretaceous and Quaternary deposits with the
latter beds having received the most attention in the present paper. The
Quaternary deposits form the recent relief. At the line separating the
Prequaternary and the Quaternary rocks, there is a neotectonic structure
closely related to the structure of the Prequaternary and the block setup
of the crystalline basement. |