Tectonic
events
The
Latvian sedimentary cover is
subdivided into four structural complexes: Baikalian, Caledonian,
Hercynian and Alpine, corresponding to the global cycles of development
of the Earth crust.
The
oil prospective area of the Baikalian Complex is formed by the Vendian (Neoproterozoic)
deposits. The Complex is observed locally onshore and offshore, its
thickness being up to 30 m.
The
Caledonian Complex is
formed by the Cambrian, Ordovician, Silurian and L. Devonian terrigenous
rocks of the Gargzdai Series, its total thickness in the oil prospective
area varies from 600 to 1200 m. It is characterised by a complex
structure with different structural components, including faults and
local highs. Main oil prospects are associated with the deposits of that
structural complex.
Deposits
of the Hercynian Complex
occur almost all over the area under discussion, excluding the Latvian
NW offshore area. Its structure is relatively simple, incorporating the
Devonian and Carboniferous deposits, their thickness reaching almost 800
m.
The
Alpine Complex consists
of the Permian, Triassic and Jurassic deposits, their thickness being
about 100 m. The Quaternary formations are also a part of that complex.
