The rocks of Orkney are dominated by flagstones and sandstones deposited in a huge fresh water lake. They belong in time to the Devonian (Old Red Sandstone) period 416 – 359 million years ago). The sediments of Lake Orcadie are superbly exposed along the many cliffs and shore platforms and so Orkney gives us one of the best examples of a Devonian lake basin in the world. The lake teemed with life, leaving many fossils, including wonderfully preserved fossil fish, and periodically dried out as desert conditions set in. Volcanic activity left lavas and vents filled with agglomerate and ash. Younger Permian (250 million years old) intrusive lamprophyre trap dykes are numerous. The oldest rock exposed in Orkney is the Precambrian Basement Complex. These outcrops represent the tops of island hills emerging from the early Lake Orcadie located in an equatorial and mid-continental desert.

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  • 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.

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  • 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.

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  • 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.

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  • 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.

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  • 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. ...

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  • 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.

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  • 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.

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