Rocks

Norway is known for its unique geology and diverse rock formations, which are a result of various geological processes it has undergone over the last 3 billion years. Norway is part of the geologic area known as the Fennoscandian Shield, also known as the Baltic Shield, which includes Norway, Sweden, Finland and the northwestern part of Russia. This segment of Earth's crust belongs to the East European Craton, which contains the oldest rocks of the European continent. The millions of years of collisions, rifts, and erosion has created conditions for igneous, sedimentary, and metamorphic rocks to form.

Sedimentary rocks are formed from the accumulation and cementation of sedimentary particles such as sand, mud, and organic matter. These rocks are mainly found along the coast and include sandstones, shales, and limestones. Sedimentary formations have primarily been of interest to the oil and gas industry in Norway due to the significant hydrocarbon potential. This has led to extensive exploration and production activities in the area. However, they are also valuable areas for geologists to study the evolution of sedimentary basins and their associated tectonic processes, depositional environments, and fossil records. The Helgeland Basin located offshore of central Norway is one such location of interest. The basin was initially formed during the Late Triassic to Early Jurassic period as a rift basin due to the extension of the continental crust. Later during the Late Jurassic, the basin underwent compression and uplift, resulting in the formation of a fold and thrust belt. During the Cretaceous period, the basin experienced a phase of subsidence due to sea-level rise and deposition of sediments (Price and Rattey). The basin's structural and stratigraphic complexity, as well as its interaction with the Mid-Norwegian Ridge, have provided a unique opportunity for geologists to study and understand the processes involved in basin formation and deformation. The Vikinghøgda Formation is another sedimentary formation of note located in Svalbard, Norway. It is considered to be one of the best records of Early Triassic chronostratigraphy in the Boreal realm due to continuous sedimentation and distinctive index fossils, with fossils dating back to the Early Triassic period. It is divided into three lithologically distinct members and is made up of marine sediments such as mudstones, shales, siltstones, and fine sandstones (Mørk et al.). The fossils are most abundant in the middle member of the formation, but index fossils can be found throughout the entire formation. Another significant location is the Batsfjord Formation in the northeastern part of Norway, in the county of Finnmark. It was formed during the Early Triassic period, approximately 251 to 247 million years ago, and consists mainly of shales, siltstones, sandstones, and conglomerates, with interbeds of limestone and volcanic rocks. It was a time of significant tectonic activity in the region, as the supercontinent Pangaea was breaking apart. The sediments were deposited in a series of basins that formed as the Earth's crust was stretched and pulled apart, with occasional influxes of volcanic material from nearby volcanic centers. As the basins filled with sediment, they eventually became buried and compressed, forming the rocks that make up the Batsfjord Formation (Siedlecka). This formation is significant because it contains fossils of marine reptiles, including ichthyosaurs and sauropterygians, which provide important insights into the evolution of these creatures during the Early Triassic period and help to fill in gaps in the fossil record from this time.

Metamorphic rocks are formed when existing rocks are subjected to high temperature and pressure, causing them to change in texture and composition. Gneiss is one of the most common metamorphic rocks in Norway, and it is found throughout the country. However, one of the most significant exposures of gneiss is in the Lofoten Islands. The islands consist of a mixture of different types of gneiss, including biotite gneiss and amphibolite gneiss. The gneiss in the Lofoten Islands is thought to have formed during the Precambrian period, around 1 billion years ago, when existing rocks were subjected to intense heat and pressure during tectonic collisions. The intense heat and pressure caused the minerals within the rocks to recrystallize and rearrange, forming the interlocking grains of quartz, feldspar, and mica that are characteristic of gneiss. The exact timing of when the Lofoten Islands took their present form is challenging to determine precisely. However, it is generally understood that the most significant shaping of the islands occurred during the last glacial period, known as the Weichselian glaciation, which took place between approximately 115,000 and 11,700 years ago. During the last glacial period, massive ice sheets covered the region, eroding the existing landforms and depositing glacial sediments. As the glaciers retreated, they left behind rugged mountains, deep fjords, and numerous islands, including the Lofoten Islands.