What is black shale composed of?

Black Shales are fine grained, generally organic carbon-rich sedimentary rocks that primarily consist of a mixture of clay minerals, quartz silt, organic particles (mostly planktonic algae and plant debris), and kerogen.

What minerals are present in shale?

Shale is a sedimentary rock composed of very fine clay particles. Clay forms from the decomposition of the mineral feldspar. Other minerals present in shale are quartz, mica, pyrite, and organic matter.

What is a black shale rock?

Black shale is a dark-colored mudrock containing organic matter that may have generated hydrocarbons in the subsurface or that may yield hydrocarbons by pyrolysis. Some black shale units have served as host rocks for syngenetic metal deposits.

Is gold found in black shale?

Black shales are favorable host rocks for many types of ore deposits (Grauch and Huyck, 1989, Starostin and Yapaskurt, 2007). Among them gold is very important, and many large and superlarge gold deposits are related to black shales.

Is black shale clastic?

Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness.

What role does kerogen play in generation?

The formation of kerogen represents a major step in the formation of oil and natural gas, as kerogen serves as the source of these fossil fuels. For kerogen to form, dead phytoplankon, zooplankton, algae, and bacteria must sink to the bottom of an ancient still water environment.

Does shale contain calcite?

What kind of rock is shale?

sedimentary rock
Shale rocks are those that are made of clay-sized particles and are have a laminated appearance. They are a type of sedimentary rock. Shale is the abundant rock found on Earth. They are usually found in areas where gentle waters have deposited sediments that become compacted together.

How do you identify black shale?

Black shales are dark-colored, usually thinly laminated mudstones containing appreciable organic matter (>0.5 wt% C), authigenic iron sulfides and, silt- and clay-sized detrital particles that in most cases have been accumulated under anoxic bottom water and/or bottom sediment conditions in marine or continental …

How are black shales rich in organic matter?

Shales that are rich in organic matter (>5%) are known as black shales. Black color is given to these rocks by organic matter. Organic matter should be decomposed in normal conditions by bacteria, but high productivity, rapid deposition and burial or lack of oxygen may preserve it. Pyrite is a common sulfide mineral in black shales.

What kind of material is in black shale?

Black shale includes large amounts of organic matter, fine and scattered pyrite, and siderite, where TOC is usually 3%–15% or more with extremely laminated bedding. Black shales and seawater also represent significant reserves of uranium, although economic extraction of uranium from each is a challenge.

What are the other constituents of shale rock?

Other constituents might include organic particles, carbonate minerals, iron oxide minerals, sulfide minerals, and heavy mineral grains. These “other constituents” in the rock are often determined by the shale’s environment of deposition, and they often determine the color of the rock.

How is the organic matter in shale formed?

Although the shale is normally gray, it may be black if it contains too much carbon material. Approximately 95% of the organic matter in the sedimentary rock is found in shale or mud. Shale is created by a process called compression. The shale exposed to extreme heat and pressure may vary in slate form.