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Sorthat Formation
The Sorthat Formation is a geologic formation on the island of Bornholm, Denmark and in the Rønne Graben in the Baltic Sea. It is of Latest Pliensbachian to Late Toarcian age. Plant fossils have been recovered from the formation, along with several traces of invertebrate animals. The Sorthat Formation is overlain by fluvial to lacustrine gravels, along with sands, clay and in some places coal beds that are part of the Aalenian-Bathonian Bagå Formation. Until 2003, the Sorthat Formation was included as the lowermost part of the Bagå Formation, recovering the latest Pliensbachian to lower Aalenian boundary. The Sorthat strata reflect a mostly marginally deltaic to marine unit. Large streams fluctuated to the east, where a large river system was established at the start of the Toarcian. In the northwest, local volcanism that started in the lower Pliensbachian extended along the North Sea, mostly from southern Sweden. At this time, the Central Skåne Volcanic Province and the Eg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacustrine Deposits
Lacustrine deposits are sedimentary rock formations which formed in the bottom of ancient lakes. A common characteristic of lacustrine deposits is that a river or stream channel has carried sediment into the basin. Lacustrine deposits form in all lake types including rift graben lakes, oxbow lakes, glacial lakes, and crater lakes. Lacustrine environments, like seas, are large bodies of water. They share similar sedimentary deposits which are mainly composed of low-energy particle sizes. Lacustrine deposits are typically very well sorted with highly laminated beds of silts, clays, and occasionally carbonates. In regards to geologic time, lakes are temporary and once they no longer receive water, they dry up and leave a formation. Lake types Lacustrine deposits can form in every variety of basins found in nature. How each basin originates is where the distinction between lacustrine deposit types stem. Rift graben lakes are formed from crustal stretching also known as rifting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is followed by the Pliensbachian. In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias. Stratigraphic definitions The Sinemurian Stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town of Semur-en-Auxois, near Dijon. The calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines. The base of the Sinemurian Stage is at the first appearance of the ammonite genera ''Vermiceras'' and '' Metophioceras'' in the stratigraphic record. A global reference profile ( GSSP or golden spike) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hettangian
The Hettangian is the earliest age and lowest stage of the Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ... Geological time scale, Period of the geologic timescale. It spans the time between 201.3 ± 0.2 annum, Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triassic Period) and is followed by the Sinemurian. In European stratigraphy the Hettangian is a part of the time span in which the Lias Group, Lias was deposited. An example is the British Blue Lias, which has an upper Rhaetian to Sinemurian age. Another example is the lower Lias from the Northern Limestone Alps where well-preserved but very rare ammonites, including Alsatites, have been found. Stratigraphic definitions The Hettangian was introduced in the literature by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciechocinek Formation
The Ciechocinek Formation (also known as the Gryfice Formation at Suliszewo), formerly known in Germany as the Green Series (German: ''Grüne Serie'') is a Jurassic (lower Toarcian) geologic formation that extends across the Baltic coast, from Grimmen, Germany, to Lithuania, with its major sequence in Poland and a few boreholes in Kaliningrad. It is mostly known by its diverse entomofauna, composed of more than 150 species of different groups of insects, as well its marine vertebrate fossils, including remains of sharks, actinopterygians and marine reptiles, along terrestrial remains of dinosaurs, including the early thyreophoran ''Emausaurus'' and others not yet assigned to a definite genus. Its exposures are mostly derived from active clay mining of a dislocated glacial raft with exposed Upper Pliensbachian to late Toarcian shallow-marine sediments. Starting with coarse and fine sand deposits with concretions, the pure clay of the Ciechocinek Formation, after the falciferum zon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Röddinge Formation
The Röddinge Formation is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic (Sinemurian-Toarcian) in age. It is a unit with a limited degree of exposure, being identified mostly by its deposits on the Fyledalen Fault Zone, specially on Kurremölla, where is present the main fossil deposit.Norling, E., Ahlberg, A., Erlström, M. & Sivhed, U. 1993: Guide to the Upper Triassic and Jurassic geology of Sweden. Sveriges Geologiska Undersökning Serie Ca 82, 71 pp. It is a unit known mostly for large museum collections and estimated to have a thickness of several hundreds of meters. It is also known for its large iron deposits. It is correlated with the mostly marine Rya Formation of western Skåne County Skåne County ( sv, Skåne län, link=no ), sometimes referred to as Scania County in English, is the most southern county, or , of Sweden, basically corresponding to the traditional province Scania. It borders the counties of Halland, Kronobe ..., the Vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nephelinite
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite). If olivine is present, the rock may be classified as an olivine nephelinite. Nephelinite is dark in color and may resemble basalt in hand specimen. However, basalt consists mostly of clinopyroxene (augite) and calcic plagioclase. Basalt, alkali basalt, basanite, tephritic nephelinite, and nephelinite differ partly in the relative proportions of plagioclase and nepheline. Alkali basalt may contain minor nepheline and does contain nepheline in its CIPW normative mineralogy. A critical ratio in the classification of these rocks is the ratio nepheline/(nepheline plus plagioclase). Basanite has a value of this ratio between 0.1 and 0.6 and also contains more than 10% olivine. Tephritic nephelinite has a value between 0.6 and 0.9. Nephelinite has a value greater than 0.9. Le Maitre (2002) defines and discusses these and other criteria in the classification of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyritic
Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all types of igneous rocks can display some degree of porphyritic texture. Most Porphyritic rocks have bimodal size ranges, meaning the rock is composed of two distinct sizes of crystal. In extrusive rocks, the phenocrysts are surrounded by a fine-grained (aphanitic) matrix or groundmass of volcanic glass or non-visible crystals, commonly seen in porphyritic basalt. Porphyritic intrusive rocks have a matrix with individual crystals easily distinguished with the eye, but one group of crystals appearing clearly much bigger than the rest, as in a porphyritic granite. The term comes from the Ancient Greek (), meaning "purple". Purple was the color of royalty, and the "imperial porphyry" was a deep purple igneous rock with large crystals of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egersund Basin
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 the island of Eigerøya. From 1838 until 1964, the town was also an independent municipality. The town has a population (2019) of 11,433 and a population density of . Egersund has one of the best natural harbours in Norway, and it used to be the largest harbour in Norway when measured in quantity of fish brought in each year (surpassed by Ålesund in 2006). Several internationally known companies have divisions here, like Navico (earlier Robertson autopilots) and Jeppesen Norway formerly C-MAP Norway (producer of electronic sea-maps). In addition, the Aker Solutions corporation owns and runs a large installation here which specializes in the building of parts for oil platforms. Most of the industry is related to the sea and to boats. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
