The Paleozoic succession and the influence of the hercynian equivalent movements in the Greater Arabian Basin

Abstract EN

During the Paleozoic, the greater Arabian Basin went through a series of epeirogenie movements contemporaneous with the regional “Hercynian orogeny”.

The early phase of these movements started around Middle Devonian and reached its maximum phase in Late Carboniferous.

The epeirogenie movements caused major stratigraphic breaks which resulted in subdivid- ing the Paleozoic succession into three mega-dcpositional cycles separated and bracketed by regional unconformities.

These cycles are; 1) Cambrian to Lower Devonian mega-dcposi- tional cycle.

2) Middle Devonian to Upper Carboniferous mega-depositional cycle, and 3) Up- permost Carboniferous to Permian and Triassic mega-depositional cycle.

The three Paleozoic mega-depositional cycles are best preserved in basinai or less tectoni- cally affected areas.

The boundary between the respective cycles in these areas are marked by a possible hiatus.

In more tectonically active areas, the Paleozoic succession is less preserved and the boundaries between the mega-cycles are more complicated due to longer periods of erosion and/or non-deposition.

In these areas, the second mega-cycle is either not deposited or eroded, and the first mega-cycle is partially or completely truncated.

Complete or partial ab- sence of pre-Upper Carboniferous rocks is attributed to the maximum phase of the tectonic movements.

The third mega-depositional cycle rest with a pronounced regional angular un- conformity on rocks ranging in age from Early Carboniferous to Precambrian.

Minor stratigraphic breaks within the mega-cycles subdiv ide them into smaller sub-cycles.

Porous Paleozoic rocks contain commercial quantities of hydrocarbons in several oilfields in the basin.