Siliciclastic (or siliclastic) rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclastic rock types include mudrock, sandstone, and conglomerate.
Siliciclastic sediments are silica-based sediments, lacking carbon compounds, which are formed from pre-existing rocks, by breakage, transportation and redeposition to form sedimentary rock.
In geology, a heavy mineral is a mineral with a density that is greater than 2.9 g/cm, most commonly referring to dense components of siliciclastic sediments. A heavy mineral suite is the relative percentages of heavy minerals in a stone. Heavy mineral suites are used to help determine the provenance and history of sedimentary rocks.
As heavy minerals are a minor constituent of most sedimentary rock, they must be separated out to be studied. Heavy mineral separation generally uses a dense liquid in either a separatory funnel or centrifuge. Liquids used include bromoform, tetrabromoethane, tribromoethane, methylene iodide, and polytungstate liquids.
Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these, along with detritus (marine snow) included. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.
The composition of pelagic sediments is controlled by three main factors. The first factor is the distance from major landmasses, which affects their dilution by terrigenous, or land-derived, sediment. The second factor is water depth, which affects the preservation of both siliceous and calcareous biogenic particles as they settle to the ocean bottom. The final factor is ocean fertility, which controls the amount of biogenic particles produced in surface waters.
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from shale by its lack of fissility.
The term mudstone is also used to describe carbonate rocks (limestone or dolomite) that are composed predominantly of carbonate mud. However, in most contexts, the term refers to siliciclastic mudstone, composed mostly of silicate minerals.
The Florida Platform is a flat geological feature that underlies all of Florida and southern Alabama and Georgia and their adjacent continental shelves. The basement of the platform, composed of igneous, metamorphic, and sedimentary rocks, was originally part of the African continent that became attached to the North American continent in the Jurassic geological period. The basement rocks are overlain by up to 5 kilometres (3.1 mi) of evaporite, carbonate, and siliciclastic sedimentary deposits that are primarily of marine origin.
The Cape Fold Belt (CFB) is a 1,300 kilometres (810 mi) long fold-and-thrust mountain belt along the western and southern coastlines of Western Cape, South Africa. The Cape Fold Belt formed during the Permian period (300 to 250 million years ago) in the late Paleozoic age, affecting the sequence of sedimentary rock layers of the siliciclastic Cape Supergroup with folding and faulted rocks, which were deposited in the Cape Basin in the southwestern corner of South Africa.
The Cape Fold Belt was once part of a larger orogenic belt with other mountain ranges that formed as part of the same tectonic event that originally extended from Argentina, across southern Africa, and into Antarctica. It included the Ventana Mountains near Bahía Blanca in Argentina, the Pensacola Mountains in East Antarctica, the Ellsworth Mountains in West Antarctica, and the Hunter–Bowen orogeny in eastern Australia. The rocks involved in this fold system are primarily sandstones and shales, with shales from the Bokkeveld Group persisting in valley floors, while the more erosion-resistant sandstones of the Peninsula Formation form the parallel ranges of the Cape Fold Mountains. The highest peak in the range is Seweweekspoortpiek, which reaches 2,325 meters.