Kukersite is a light-brown marine type

oil shale Oil shale is an organic-rich Granularity, fine-grained sedimentary rock containing kerogen (a solid mixture of Organic compound, organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general compos ...

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

age. It is found in the Baltic Oil Shale Basin in

Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

and North-West

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. It is of the lowest Upper Ordovician formation, formed some 460 million years ago. It was named after the German name of the Kukruse Manor in the north-east of Estonia by the Russian

paleobotanist Paleobotany or palaeobotany, also known as paleophytology, is the branch of botany dealing with the recovery and identification of plant fossils from geological contexts, and their use for the biological reconstruction of past environments (pale ...

Mikhail Zalessky Mikhail Dmitrievich Zalessky (, ''Mikhail Dmitrievich Zalesskiy''; 15 September 1877 – 22 December 1946) was a Russian paleontologist and paleobotanist. His main focus was an investigation of plant remains in coals and oil shales. In 1911, Z ...

in 1917. Some minor kukersite resources occur in sedimentary basins of Michigan, Illinois, Wisconsin, North Dakota, and Oklahoma in North America and in the Amadeus and

Canning Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although under ...

basins of Australia.

Baltic Oil Shale Basin

The Baltic Oil Shale Basin covers about . Main kukersite deposits are Estonian and Tapa deposits in Estonia, and Leningrad deposit in Russia (also known as Gdov or Oudova deposit). Other occurrences in Russia are Veimarn and Chudovo–Babinskoe deposits. The Estonian deposit, which covers about , is exploited industrially; the Tapa deposit is not accounted as reserves due its lower value which makes its extraction economically inexpedient. The Leningrad deposit was exploited industrially but operations have ceased.

Geology

Stratigraphic section of the kukersite deposits in northern Estonia

Kukersite occurs within the Kukruse and Uhaku stages of the Viivikonna and Kõrgekallas formations, as an often calcareous layer. In northern Estonia there are a total of 50 oil shale layers of kukersite, of which six lowest form a thick mineable bed. In this part kukersite lies near the surface while southward and westward its depth increases and its thickness and quality decreases. Estonia's kukersite represents about 1.1% of global and 17% of European oil shale resources. The total kukersite resources in Estonia are estimated to be about 4.8 billion tonnes, including about 1 billion tonnes economically proven reserve, 0.3 billion tonnes economic probable reserve and about 3.5 billion tonnes uneconomical proven and probable reserve. Economically proven and probable reserves forms active resource, which is defined as mineable deposits with energy ratings of at least 35 gigajoules per square metre and

calorific value The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The ''calorific value'' is the total energy release ...

s of at least 8 MJ/kg, located in areas without environmental restrictions. Energy rating of the oil shale mining block is calculated as the sum of the products of thickness, calorific values and densities of all oil shale layers and

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

interlayers. Up to 50% of active resources are designated as recoverable. The Leningrad deposit consists of 3.6 billion tonnes of kukersite, including more than one billion tonnes of economically proven and probable reserves.

Composition

Estonian kukersite deposits are one of the world's highest-grade deposits with organic content varying from 15% to 55% with average more than 40%, and it has 65–67% conversion ratio into shale oil and oil shale gas. Fischer Assay oil yield is 30 to 47%. Its organic matter has an atomic ratio of

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

of 1.51 and the mean calorific value of kukersite is 3600 kcal/kg. The principal organic component of kukersite is

telalginite Telalginite is a structured organic matter (alginite) in sapropel, composed of large discretely occurring colonial or thick-walled Microorganism, unicellular algae such as ''Botryococcus'', ''Tasmanites'' and ''Gloeocapsomorpha prisca''. Telalginite ...

, derived from the fossil

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

, ''Gloeocapsomorpha prisca'', which has affinities with the modern

cyanobacterium Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria' ...

, ''Entophysalis major'', an extant species that forms algal mats in inter-tidal to very shallow subtidal waters.

Matrix Matrix (: matrices or matrixes) or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the m ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s dominantly include low-

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, dolomite, and siliciclastic minerals. They are not rich in heavy metals. Kukersite was deposited in a shallow marine basin. It lies in the depth of .

References

{{Reflist Oil shale geology Geology of Estonia Geology of Russia Oil shale in Estonia Oil shale in Russia

Baltic Oil Shale Basin

Geology

Composition

See also

References