An ore shoot is a hypogenic mass that is deposited in veins within a planar channel or lode, found in a shear or fault zone, fissure or lithologic boundary. [1] The ore shoot is the area of concentration which contains a primary ore along the veins present in the rock, and consists of the most valuable part of the deposit. [2]
Along an ore shoot, there is a rich gathering of different minerals within a vein. The veins can resemble a pipe, chimney or ribbon in structure and are displaced mainly vertically oriented but also can be horizontal with large veins extending approximately 30 m (100 ft) horizontally and 150 m (500 ft) vertically. [3] The metal contents in ore shoots are distributed in areas that vary in deposit sizes. When several lodes meet, they connect to form vein systems, these systems contain common fluid sources which causes general homogeneity within the mineralization types and ore shoot controls resulting in the veins sharing a common plumbing system. [1]
In gold vein deposits the ore shoots tend to be deposited in an elongated plunging direction. The majority of the time the ore shoot plunge for orogenic gold deposits arises from the mineral deposition and direction of the fluid flow controlled by structures. [4]
The circumference of deposit sizes can range from a few meters, to many kilometres. A structure may consist of multiple ore shoots with some veins or lodes being as thick as 1.5–6.1 m (5–20 ft), and extending to thousands of feet horizontally and vertically. [3] The shoots tends to be thicker and richer in center areas rather than being distributed equally.The geometrical values of the ore shoot are expressed using the breadth, dip and strike lengths as well as the plunge lengths. The average mass for most ore shoots are between 1 x 10^6 and 2 x 10^4 tonnes. [1]
There are complex stratigraphic historical parameters required in understanding how ore shoots are formed. Rocks go through numerous ductile and brittle deformation events before they become mineralized. The different locations of ore shoots in Australia are determined by investigating the internal architecture of the rock pile. The longest shoots occur on the flanks of the basalt flows with the largest lateral extent. The geometry and internal structure of the basalt flows is important for predicting the likelihood and extent of the ore shoots. [5] The catalytic effect of different geological events leading up to an ore shoot formation is called "ground preparation". [1] Varying forms of ground preparation are; 1. sequential deformation which produces grain in the ore district. 2. sever faulting and jointing that enhances the permeability and surface area where the ore minerals can precipitate. 3. Interplay between the ore fluid deformation which produces an ore shoot. [1]
Found in the Guangxi region in South China, the Jianzhupo Sb-Pb-Zn-Ag deposit has been explored and studied over decades, by using different parameters to understand the formation. [4] These include the use of geological fluid inclusions as well as H-O isotopic data that can be found during the mineralization's main stage. The Jianzhupo deposit is located within the Danchi Sn-polymetalic belt, and experienced major faulting and subsidence during the Devonian-Carboniferous Periods following folding during the Middle Triassic, and then finally underwent extension during the Cretaceous. The deposit was drilled into for fluid inclusions samples at varying depths, recovering 30 thin sections that were then used for petrographic fluid inclusion analysis. [4]
Ore is natural rock or sediment that contains one or more valuable minerals concentrated above background levels, typically containing metals, that can be mined, treated and sold at a profit. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral.
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation (strain) in the rocks, and ultimately, to understand the stress field that resulted in the observed strain and geometries. This understanding of the dynamics of the stress field can be linked to important events in the geologic past; a common goal is to understand the structural evolution of a particular area with respect to regionally widespread patterns of rock deformation due to plate tectonics.
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep.
In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning dates from the 17th century, being an expansion of an earlier sense of a "channel, watercourse" in Late Middle English, which in turn is from the 11th-century meaning of lode as a "course, way".
Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name. In later stages, circulating meteoric fluids may interact with the magmatic fluids. Successive envelopes of hydrothermal alteration typically enclose a core of disseminated ore minerals in often stockwork-forming hairline fractures and veins. Because of their large volume, porphyry orebodies can be economic from copper concentrations as low as 0.15% copper and can have economic amounts of by-products such as molybdenum, silver, and gold. In some mines, those metals are the main product.
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation.
In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics.
The Yilgarn Craton is a large craton that constitutes a major part of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have been dated at ~4.27 Ga, with one detrital zircon dated as old as 4.4 Ga.
The Petermann Orogeny was an Australian intracontinental event that affected basement rocks of the northern Musgrave Province and Ediacaran (Proterozoic) sediments of the (now) southern Amadeus Basin between ~550-535 Ma. The remains are seen today in the Petermann Ranges.
The Challenger mine is a gold mine in the Far North of South Australia, 165 km west of the Stuart Highway and 740 km north-west of Adelaide. It was operated by Dominion, Kingsgate and then WPG Resources. The mine is now on Care and Maintenance. The deposit was named by the geologist who discovered it, after his dog.
The Broken Hill Ore Deposit is located underneath Broken Hill in western New South Wales, Australia, and is the namesake for the town. It is arguably the world's richest and largest zinc-lead ore deposit.
Uranium ore deposits are economically recoverable concentrations of uranium within Earth's crust. Uranium is one of the most common elements in Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.
Iron oxide copper gold ore deposits (IOCG) are important and highly valuable concentrations of copper, gold and uranium ores hosted within iron oxide dominant gangue assemblages which share a common genetic origin.
The Muruntau gold deposit is situated in the Qizilqum Desert of Uzbekistan. It is being mined in the world's largest open-pit gold mine with production believed to be of the order of two million ounces per annum. The open pit measures about 3.5 by 2.5 km and extends to a depth of 560m (2012). The gold ore resource in the Muruntau deposit, including production, is about 170 million ounces of gold. This gives the mine a reserves-to-production ratio of 85 years. The mine is owned and operated by Uzbekistan state-owned Navoi Mining and Metallurgy Combinat.
Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce metallic-rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. In some occurrences, minerals can be extracted for a profit by mining. Discovery of mineral deposits consumes considerable time and resources and only about one in every one thousand prospects explored by companies are eventually developed into a mine. A mineral deposit is any geologically significant concentration of an economically useful rock or mineral present in a specified area. The presence of a known but unexploited mineral deposit implies a lack of evidence for profitable extraction.
Fault zone hydrogeology is the study of how brittlely deformed rocks alter fluid flows in different lithological settings, such as clastic, igneous and carbonate rocks. Fluid movements, that can be quantified as permeability, can be facilitated or impeded due to the existence of a fault zone. This is because different mechanisms that deform rocks can alter porosity and permeability within a fault zone. Fluids involved in a fault system generally are groundwater and hydrocarbons.
Michel Jébrak is a Franco-Canadian geologist, academic and a researcher. He is an emeritus professor at University of Quebec’s Department of Earth and Atmospheric Sciences. He is a former Vice-Rector for Research and Creation at UQAM and holder of the UQAT-UQAM Mining Entrepreneurship Chair.
An orogenic gold deposit is a type of hydrothermal mineral deposit. More than 75% of the gold recovered by humans through history belongs to the class of orogenic gold deposits. Rock structure is the primary control of orogenic gold mineralization at all scales, as it controls both the transport and deposition processes of the mineralized fluids, creating structural pathways of high permeability and focusing deposition to structurally controlled locations.
The Kanggurtag gold belt is a gold belt in the Eastern Tianshan portion of the Xinjiang province of Northwestern China. During the late Proterozoic, the Tarim plate and the Junggar plate collided, creating the Tianshan mountains. Around 276 Ma, the collision related stress regime ended and was replaced by dextral slip movement that lasted from 276 to 239 Ma. During the strike-slip period in the region, the Kanggurtag gold belt formed during the late Carboniferous-early Permian. This gold belt is separated into three groups: shear zoned dominated gold deposits, epithermal gold deposits, and intrusion related gold deposits.