Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated, although there are exceptions. In geology, the term "marble" refers to metamorphosed limestone, but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material.
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies. Sedimentation may also occur as dissolved minerals precipitate from water solution.
Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation, transport, deposition and diagenesis. Sedimentologists apply their understanding of modern processes to interpret geologic history through observations of sedimentary rocks and sedimentary structures.
BHP, formerly known as BHP Billiton, is the trading entity of BHP Group Limited and BHP Group plc, an Anglo-Australian multinational mining, metals and petroleum dual-listed public company headquartered in Melbourne, Victoria, Australia.
Petrology is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock.
In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and may be able to operate at higher revolutions per minute (RPM) than a two-valve engine, delivering more power.
Algal mat is one of many types of microbial mat formed on the water surface or on the surface of rocks. It is made out of blue-green cyanobacteria and sediments. It is formed by having alteration layers between the blue-green bacteria and sediments, creating dark-laminated layers. Stromatolites are prime examples of algal mat. Algal mats played an important role in the Great Oxidation Event on Earth some 2.3 billion years ago. Overpopulation of algal mat may be an ecological problem, when mats disrupt the other underwater marine life by blocking the sunlight.
The sulfur cycle is the collection of processes by which sulfur moves to and from rock, waterways and living systems. Such biogeochemical cycles are important in geology because they affect many minerals. Biochemical cycles are also important for life because sulfur is an essential element, being a constituent of many proteins and cofactors.
Organic-rich sedimentary rocks are a specific type of sedimentary rock that contains significant amounts (>3%) of organic carbon. The most common types include coal, lignite, oil shale, or black shale. The organic material may be disseminated throughout the rock giving it a uniform dark color, and/or it may be present as discrete occurrences of tar, bitumen, asphalt, petroleum, coal or carbonaceous material. Organic-rich sedimentary rocks may act as source rocks which generate hydrocarbons that accumulate in other sedimentary "reservoir" rocks. Potential source rocks are any type of sedimentary rock that the ability to dispel available carbon from within it. Good reservoir rocks are any sedimentary rock that has high pore-space availability. This allows the hydrocarbons to accumulate within the rock and be stored for long periods of time. Highly permeable reservoir rocks are also of interest to industry professionals, as they allow for the easy extraction of the hydrocarbons within. The hydrocarbon reservoir system is not complete however without a "cap rock". Cap rocks are rock units which have very low porosity and permeability, which trap the hydrocarbons within the units below as they try to migrate upwards.
Hopane is a natural chemical compound classified as a triterpene. It forms the central core of a variety of other chemical compounds which are collectively known as hopanoids.
Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. The new pore-filling minerals forms "bridges" between original sediment grains, thereby binding them together. In this way sand becomes "sandstone", and gravel becomes "conglomerate" or "breccia". Cementation occurs as part of the diagenesis or lithification of sediments. Cementation occurs primarily below the water table regardless of sedimentary grain sizes present. Large volumes of pore water must pass through sediment pores for new mineral cements to crystallize and so millions of years are generally required to complete the cementation process. Common mineral cements include calcite, quartz or silica phases like cristobalite, iron oxides, and clay minerals, but other mineral cements also occur.
In petroleum geology, source rock refers to rocks from which hydrocarbons have been generated or are capable of being generated. They form one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been deposited in a variety of environments including deep water marine, lacustrine and deltaic. Oil shale can be regarded as an organic-rich but immature source rock from which little or no oil has been generated and expelled. Subsurface source rock mapping methodologies make it possible to identify likely zones of petroleum occurrence in sedimentary basins as well as shale gas plays.
All TD series engines were four-cylinder diesel overhead valve engines, except the TD42 which was a six-cylinder.
Microbially induced sedimentary structures (MISS) are primary sedimentary structures formed by the interaction of microbes with sediment and physical agents of erosion, deposition, and transportation. The structures commonly form when microbial mats are preserved in the sedimentary geological record. There are 17 main types of macroscopic and microscopic MISS. Of those, wrinkle structures and microbial mat chips are the most abundant in the fossil record. Other MISS include sinoidal structures, polygonal oscillation cracks, multidirected ripple marks, erosional remnants and pockets, or gas domes.
Irvine Island is located off the Kimberley coast of Western Australia in the Buccaneer Archipelago. It is about 250 km (160 mi) north-east of Broome, 140 km (87 mi) north of Derby and hosts an unmined deposit of iron ore. Irvine Island has a surface area of 893 hectares and is 5 kilometres (3 mi) west of Cockatoo Island.
Andrew Stewart Mackenzie FRS is a Scottish businessman, CEO of BHP Billiton, the world's largest mining company. He succeeded Marius Kloppers on 10 May 2013. In 2014, he was paid $7,123,000 in total compensation.
The Cannington Silver and Lead Mine is an Australian underground mine located in north-west Queensland, in the Shire of McKinlay, about 200 kilometres (124 mi) southeast of Mount Isa. The deposit was discovered by Broken Hill Proprietary Company (BHP) in 1990. Although sitework and underground mining began in 1997, full production was not achieved until early 1999, with 1.5 million tons of ore processed in 1999. Production since has reached 3 million tons of ore per year. As of 2010 it was the largest and lowest cost silver and lead mine in the world. The expected life of the Cannington mine is 25 years. On August 19, 2014, the mine's owner BHP Billiton announced it was splitting the company in two. A newly formed entity called South32 is to house BHP Billiton's non-core businesses including the Cannington Mine. South32 is listed on the Australian Securities Exchange, with a secondary listing in Johannesburg.
