Sedimentary Rocks Sedimentary rock sandstone Sedimentary rock limestone

Sedimentary Rocks

Sedimentary rock sandstone

Sedimentary rock limestone

Sedimentary rock shale

Sedimentary Rocks Sedimentary rocks form from sediment, which is the product of weathering. Sedimentary rocks make up about 75% of all rock outcrops on Earth’s continents. These rocks are used to reconstruct much of Earth’s history, as they provide clues to past environments and sediment transport. Sedimentary rocks often contain fossils.

Sedimentary Rocks Sedimentary rocks are of tremendous economic importance because they can contain fossil fuels: coal oil natural gas They are also sources of iron and aluminum.

Sedimentary Rocks Sediments are loose rock particles which can be produced by: 1) weathering of preexisting rocks, followed by transportation and deposition. 2) chemical precipitation of minerals from water. 3) accumulation of biological matter (shells, plant fragments). Sediments that are buried may harden into sedimentary rock thru a process know as lithification.

Sedimentary Rocks Therefore there are two basic classifications of sedimentary rocks: • Detrital sedimentary rocks form from the cementation of sediment grains that come from pre-existing rocks. This is the most common sedimentary rock type. They are classified by grain size, and to a lesser extent by chemical composition. • Chemical and biological sedimentary rocks form by the precipitation of minerals from water (this process may or may not involve the actions of organisms). In contrast to the clastic textures of the detrital rocks discussed above, chemical sedimentary rocks have crystalline textures.

Detrital Sedimentary Rocks

Detrital Sedimentary Rocks breccia (coarse, angular particles) sandstone (medium particles) shale (very fine particles) conglomerate (course, rounded particles) siltstone (fine particles)

Chemical Sedimentary Rocks

Chemical Sedimentary Rocks Chalk fossiliferous limestone coquina (shell fragments) Agate flint jaspe r

Chemical Sedimentary Rocks evaporate deposits

Detrital Sedimentary Rocks Conglomerate is a coarse-grained clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts, e. g. , granules, pebbles, cobbles, and boulders, larger than 2 mm (0. 079 in) in diameter. Conglomerates form by the consolidation and lithification of gravel. Conglomerates typically contain finer grained sediment, e. g. , either sand, silt, clay or combination of them, called matrix by geologists, filling their interstices and are often cemented by calcium carbonate, iron oxide, silica, or hardened clay. The size and composition of the gravel-size fraction of a conglomerate may or may not vary in composition, sorting, and size. In some conglomerates, the gravelsize class consist almost entirely of what were clay clasts at the time of deposition. Conglomerates can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. In terms of origin and depositional mechanisms, they are closely related to sandstones and exhibit many of the same types of sedimentary structures, e. g. , tabular and trough crossbedding and graded bedding.

Detrital Sedimentary Rocks Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix that can be similar to or different from the composition of the fragments. A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia.

Detrital Sedimentary Rocks Sandstone is a clastic sedimentary rock composed mainly of sandsized minerals or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are: tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs.

Detrital Sedimentary Rocks Siltstone is a clastic sedimentary rock. As its name implies, it is primarily composed (greater than 2/3) of silt sized particles, defined as grains 2– 62 µm. Siltstones differ significantly from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction. Although often mistaken as a shale, siltstone lacks the fissility and laminations which are typical of shale. Siltstones may contain concretions. Unless the siltstone is fairly shaly, stratification is likely to be obscure and it tends to weather at oblique angles unrelated to bedding. Mudstone or shale are rocks that contain mud, which is material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay.

Detrital Sedimentary Rocks Shale is a finegrained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. Mudstones, on the other hand, are similar in composition but do not show the fissility.

Chemical Sedimentary Rocks Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, creamcolored, and even rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems. It is frequently used in Italy and elsewhere as a building material. Travertine is a terrestrial sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters, and/or geothermally heated hot-springs. Similar (but softer and extremely porous) deposits formed from ambient-temperature water are known as tufa.

Chemical Sedimentary Rocks Crystalline Limestone Crystalline limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (Ca. CO 3). Most limestone is composed of skeletal fragments of marine organisms such as coral, forams and molluscs. Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock. Limestone has numerous uses: as a building material, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, and as a chemical feedstock for the production of lime.

Chemical Sedimentary Rocks Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachi opods, or other invertebrates. For a sediment to be considered to be a coquina, the particles composing it should average 2 mm or greater in size. Coquina can vary in hardness from poorly to moderately cemented. Incompletely consolidated and poorly cemented coquinas are considered grainstones in the Dunham classification system for carbonate sedimentary rocks. Coquinas accumulate in high-energy marine and lacustrine environments where currents and waves result in the vigorous winnowing, abrasion, fracturing, and sorting of the shells, which compose them.

Chemical Sedimentary Rocks Fossiliferous Limestone Fossiliferous limestone is any type of limestone, made mostly of calcium carbonate (Ca. CO 3) in the form of the minerals calcite or aragonite, that contains an abundance of fossils or fossil traces. The fossils in these rocks may be of macroscopic or microscopic size. The sort of macroscopic fossils often include crinoid stems, brachiopods, ga stropods, and other hard shelled mollusk remains. In some cases, microfossils such as siliceous diatom shells in deposition may convert overtime to opal and chert, providing the only inferred evidence of bioactivity preserved in limestone.

Chemical Sedimentary Rocks Chalk is a soft, white, porous sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or Ca. CO 3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores. Flint (a type of chert unique to chalk) is very common as bands parallel to the bedding or as nodules embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i. e. replaced molecule by flint).

Chemical Sedimentary Rocks Chert is a fine-grained silicarich microcrystalline, cryptocrystal line or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced forms respectively).

Chemical Sedimentary Rocks Flint is a hard, sedimentary cryptocrystallin e form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white or brown in color, and often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually different in color, typically white and rough in texture. From a petrological point of view, "flint" refers specifically to the form of chert which occurs in chalk or marly limestone. Similarly, "common chert" (sometimes referred to simply as "chert") occurs in limestone.

Chemical Sedimentary Rocks Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula Ca. SO 4· 2 H 2 O. It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures. It is the definition of a hardness of 2 on the Mohs scale of mineral hardness. It forms as an evaporite mineral and as a hydration product of anhydrite.

Chemical Sedimentary Rocks Rock Salt Halite, commonly known as rock salt, is a type of salt, the mineral form of sodium chloride (Na. Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates.

Chemical Sedimentary Rocks Bituminous Coal Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than anthracite. Formation is usually the result of high pressure being exerted on lignite. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. These distinctive sequences, which are classified according to either "dull, bright-banded" or "bright, dull-banded", is how bituminous coals are stratigraphically identified.

The Launch Pad 1/4 Monday, 2/27/17 What is the main difference between the three types of sedimentary rocks: detrital, chemical, and biological? Detrital sedimentary rocks are formed from sediment that originated as solid particles from weathered rocks. Chemical sedimentary rocks are formed from material that was once in water solution and precipitated back to form solid chemical sediment. Biological sedimentary rocks are formed from organic material such as shells or plant fragments that was compressed over time beneath the Earth’s surface.

The Launch Pad 2/4 Monday, 2/27/17 Name the following sedimentary rocks. Shale (detrital)

The Launch Pad 3/4 Monday, 2/27/17 Name the following sedimentary rocks. Limestone (chemical)

The Launch Pad 4/4 Monday, 2/27/17 Name the following sedimentary rocks. Sandstone (detrital)