Over two hundred “Trap Dykes” of igneous origin cut the Devonian sediments of Orkney in a NE-SW direction, but a small group in southeast Orkney runs N-S. This “Camptonite – Monchiquite Suite” of dykes is part of a set of nine similar dyke swarms found in the Highlands and Islands, widely distributed both in space and time.

permian Dykes Birsay

These hard, black rocks often follow the line of fractures. They are notable in occasionally exhibiting an exotic collection of mantle-derived xenolith inclusions, indicating rapid transport of the host liquids from great depths. It is possible that these dykes never reached the surface to form volcanoes. The age of the Orkney dykes is 252+/-10 million years, placing the time of intrusion in the late Permian, a period of renewed tectonic movement in the sedimentary basins to the west of Orkney.

Geology of Orkney

  • Orkney Stratigraphy

    The Orkney Islands consist almost entirely of sedimentary rocks and subordinate lavas and tuffs of Middle and Upper Old Red Sandstone age. A Basement Complex composed of metamorphic rocks of Moinian type and Caledonian granites forms a number of small inliers near Yesnaby and Stromness in West Mainland and on the island of Graemsay.

  • Devonian environments

    During the Devonian Period, North America and Northern Europe were joined together forming Euramerica, one of the three major continental masses on the Devonian globe, with Orkney placed south of the equator. Most of Britain formed part of this landmass with mountains in the northwest and the open marine Devonian Sea covering southwest England.

  • Hydrocarbon Potential

    The Petroleum System consists of four main Geologic components, source, reservoir, seal and trap plus additional processes necessary to generate and store hydrocarbons in the subsurface. Their presence is required to generate a viable EXPLORATION TARGET.

  • Tertiary of the northern North Sea

    At the opening of the Tertiary chalk sedimentation continued on the northern North Sea. Starting around 63 Ma, the East Shetland Platform was uplifted and tilted towards the south-east. ...

  • Quaternary of the northern North Sea

    The Quaternary deposits found on the East Shetland Platform are thin (Johnson et al., 1993). The Quaternary thickens above the Viking Graben to as much as 300m and provides a long and relatively detailed record of glaciation.

  • Mesozoic of the northern North Sea

    Rifting in the Northern North Sea commenced during the early Triassic, peaked during the late Jurassic, and terminated by the late Cretaceous. The Viking Graben can be seen as a failed arm of proto-Atlantic rift. Almost throughout this period, the Shetland area formed an area of positive relief.