Utsira High no, Utsirahøgda is a

basement high In geology, a basement high is a portion of the basement in a sedimentary basin that is higher than its surroundings. Commonly, structures referred to as basement highs are hidden by the sedimentary fill of the basin. Usually basement highs are ...

and horst in the southwest of the

Norwegian continental shelf The Norwegian continental shelf ( no, Den norske kontinentalsokkelen) (abbreviated as NCS) is the continental shelf over which Norway exercises sovereign rights as defined by the United Nations Convention on the Law of the Sea. The area of the s ...

. It lies east of the Viking Graben and west of the

Stord Stord is a municipality in Vestland county, Norway. It is located in the traditional district of Sunnhordland. Stord is sometimes called "Norway in miniature" since it has such a variety of landscapes: coastline, fjords, forests, agricultural l ...

and

Egersund Egersund is a town in Eigersund municipality in Rogaland county, Norway. The town is located along the southwestern coast of Norway, about south of the city of Stavanger. The town is situated along a strait which separates the mainland from t ...

basins Basin may refer to: Geography and geology * Depression (geology) ** Back-arc basin, a submarine feature associated with island arcs and subduction zones ** Debris basin, designed to prevent damage from debris flow ** Drainage basin (hydrology), a ...

190 km west of

Stavanger Stavanger (, , American English, US usually , ) is a city and municipalities of Norway, municipality in Norway. It is the fourth largest city and third largest metropolitan area in Norway (through conurbation with neighboring Sandnes) and the a ...

. It was on the Balder oil field at the flank of the Utsira High that oil was first discovered in Norway in 1967. The

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

is of Utsira High is composed of

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

that formed in

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

times. Parts of these granites contain

saprolite Saprolite is a chemically weathered rock. Saprolites form in the lower zones of soil profiles and represent deep weathering of the bedrock surface. In most outcrops its color comes from ferric compounds. Deeply weathered profiles are widespread o ...

and saprock that formed from

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

above sea level during the Early Mesozoic. before they became buried in

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

and

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

-aged

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

. These weathered rocks may be unconventional petroleum reservoirs. The strandflat at Bømlo island is considered a

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

-free equivalent to the Utsira High.

References

Basement highs Geology of Norway Geology of the North Sea Petroleum in Norway Unconformities Horsts (geology) {{geology-stub