e measurement of the permeability, or ability to flow or transmit fluids through a rock, conducted when a single

fluid, or phase, is present in the rock. The symbol most commonly used for permeability is k, which is measured in

units of darcies or millidarcies.

(a)  

The measurement of pressure relative to the pressure in a vacuum, equal to the sum of the pressure shown on a

pressure gauge and atmospheric pressure.

(a)  

The deepest area of the ocean basins. The depositional energy is low and fine-grained sediments are deposited

slowly by waning turbidity currents or from suspension in the water. The water is thousands of meters deep

(>2,000 m) [>6,520 ft] so it is cold and sunlight is minimal.

(a)  

Pertaining to the depositional environment of the deepest area of the ocean basins, the abyss. The depositional

energy is low, the abyssal plain is flat and nearly horizontal, and fine-grained sediments are deposited slowly by

waning turbidity currents or from suspension in the water. The water is thousands of meters deep (> 2000 m)

[6520 ft], so the water is cold and sunlight is minimal.

(a)  

Sequence stratigraphic term for the amount of space available for sediment accumulation.

(a)  

1. n. [Geology]

The phase in the development of a petroleum system during which hydrocarbons migrate into and remain trapped

in a reservoir.

See: critical moment, generation, hydrocarbon, migration, preservation, primary migration

2. n. [Geology]

An occurrence of trapped hydrocarbons, an oil field.

(a)  

A boundary of colliding lithospheric plates. The present subduction zones of the Pacific Rim, the older mountains

of the Alps, and the Himalayas represent active margins.

(a)  

Pertaining to the environment of deposition of sediments by wind, such as the sand dunes in a desert. Because

fine-grained sediments such as clays are removed easily from wind-blown deposits, eolian sandstones are typically

clean and well-sorted.

(a)  

Predictable variation of a property of a material with the direction in which it is measured, which can

occur at all scales. For a crystal of a mineral, variation in physical properties observed in different

directions is aeolotropy (also known as anisotropy). In rocks, variation in seismic velocity measured

parallel or perpendicular to bedding surfaces . Often found where platy minerals

such as micas and clays align parallel to depositional bedding as sediments are compacted, ... is

common in shales.

(a)  

e surface or near-surface, unconsolidated sedimentary layer that has been subject to weathering and whose

pores are air-filled instead of liquid-filled. An aerated layer typically has a low seismic velocity.

(a)  

The accumulation of stratigraphic sequences by deposition that stacks beds atop each other, building upwards

during periods of balance between sediment supply and accommodation

(a)  

Related to the accumulation of stratigraphic sequences by deposition that stacks beds atop each other, building

upwards during periods of balance between sediment supply and accommodation.

(a)  

A telescopic surveying device used to construct surface topographic and geologic maps in the field. The alidade is

mounted on a plane table, which has a sheet of paper on which to draw the map, and an object or location is

sighted through the alidade. The edge of the alidade is aligned in the azimuthal direction of the object or location.

The vertical angle from which elevation of the location can be calculated is measured using the calibrated arc of

the alidade.

(a)  

A rock mass formed somewhere other than its present location, which was transported by fault

movements, large-scale gravity sliding, or similar processes.

(a)  

Pertaining to materials, particularly rock masses, that formed somewhere other than their present location,

and were transported by fault movements, large-scale gravity sliding, or similar processes. Autochthonous

material, in contrast, formed in its present location. Landslides can result in large masses of allochthonous

(a)  

Pertaining to minerals or rock fragments that formed in one location but were transported to another location and

deposited. Clastic sediments in a rock such as sandstone are allogenic, or formed elsewhere

(a)  

Pertaining to the subaerial (as opposed to submarine) environment, action and products of a stream or river on its

floodplain, usually consisting of detrital clastic sediments, and distinct from subaqueous deposition such as in lakes

or oceans and lower energy fluvial deposition. Sediments deposited in an alluvial environment can be subject to

high depositional energy, such as fast-moving flood waters, and may be poorly sorted or chaotic

(a)  

Material deposited in an alluvial environment, typically detrital sediments that are poorly sorted.

(a)  

. adj. [Geology]

The condition of an environment in which free oxygen is lacking or absent.

Synonyms: anoxic

2. adj. [Geology]

A description of organisms that can survive in the absence of oxygen, particularly bacteria.

3. adj. [Drilling Fluids]

Pertaining to systems, reactions or life processes of species, such as bacteria, in which atmospheric oxygen is not

present or not required for survival.

(a)  

A surface that separates younger strata from eroded, dipping, older strata and represents a gap in the geologic

record.

(a)  

Having directionally dependent properties. For a crystal of a mineral, variation in physical properties

observed in different directions is anisotropy. In rocks, variation in seismic velocity measured parallel or

perpendicular to bedding surfaces is a form of anisotropy. Often found where platy minerals such as

micas and clays align parallel to depositional bedding as sediments are compacted, anisotropy is common

in shales.

(a)  

Predictable variation of a property of a material with the direction in which it is measured, which can

occur at all scales. For a crystal of a mineral, variation in physical properties observed in different

directions is anisotropy. In rocks, variation in seismic velocity measured parallel or perpendicular to

bedding surfaces is a form of anisotropy. Often found where platy minerals such as micas and clays align

parallel to depositional bedding as sediments are compacted, anisotropy is common in shales.

(a)  

Different from what is typical or expected, or different from what is predicted by a theoretical model. The

difference or anomaly may refer to the measurement of the difference between an observed or measured value

and the expected values of a physical property. Anomalies can be of great interest in hydrocarbon and

mineral exploration because they often indicate hydrocarbon and mineral prospects and accumulations, such as

geologic structures like folds and faults. Geochemical anomalies at the surface of the Earth can also indicate

an accumulation of hydrocarbons at depth. Geophysical anomalies, such as amplitude anomalies

in seismic data and magnetic anomalies in the Earth's crust, can also be associated with hydrocarbon

accumulations.

(a)  

An entity or property that differs from what is typical or expected, or which differs from that predicted by a

theoretical model. May be the measurement of the difference between an observed or measured value and the

expected values of a physical property. Anomalies can be of great interest in hydrocarbon and mineral exploration

because they often indicate hydrocarbon and mineral prospects and accumulations, such as geologic structures

like folds and faults. Geochemical anomalies at the surface of the Earth can also indicate an accumulation of

hydrocarbons at depth. Geophysical anomalies, such as amplitude anomalies in seismic data and magnetic

anomalies in the Earth's crust, can also be associated with hydrocarbon accumulations.

Alternate Form: anomalous

(a)  

The condition of an environment in which free oxygen is lacking or absent.

(a)  

Pertaining to an anticline, an arch-shaped fold in rock in which rock layers are upwardly convex. The oldest rock

layers form the core of the fold, and outward from the core progressively younger rocks occur. Anticlines form

many excellent hydrocarbon traps, particularly in folds with reservoir-quality rocks in their core

and impermeable seals in the outer layers of the fold. A syncline is the opposite type of fold, having downwardly

convex layers with young rocks in the core

(a)  

An arch-shaped fold in rock in which rock layers are upwardly convex. The oldest rock layers form the core of the

fold, and outward from the core progressively younger rocks occur. Anticlines form many excellent hydrocarbon

traps, particularly in folds with reservoir-quality rocks in their core and impermeable seals in the outer layers of the

fold. A syncline is the opposite type of fold, having downwardly convex layers with young rocks in the core.

(a)  

A minor, secondary fault, usually one of a set, whose sense of displacement is opposite to its associated major and

synthetic faults. Antithetic-synthetic fault sets are typical in areas of normal faulting.

(a)  

The angle that a plane makes with the horizontal measured in any randomly oriented section rather than

perpendicular to strike.

(a)  

The phase of petroleum operations that immediately follows successful exploratory drilling. During appraisal,

delineation wells might be drilled to determine the size of the oil or gas field and how to develop it most

efficiently.

(a)  

A body of rock whose fluid saturation, porosity and permeability permit production of groundwater.

More Details:

• Near-Surface Electromagnetic Surveying

2. n. [Geology]

A water-bearing portion of a petroleum reservoir with a waterdrive.

3. n. [Drilling]

Any water-bearing formation encountered while drilling. Drillers often are concerned about aquifers and

are required to take special precautions in the design and execution of the well plan to protect fresh water

aquifers from contamination by wellbore fluids. Water in aquifers can flow into the wellbore, contaminate

drilling fluids and cause well control problems.

(a)  

Describing sandy-textured rock or sediment. Arenaceous does not necessarily imply silica-rich, but rather particles

of sand size, 0.625 to 2 mm, according to the Udden-Wentworth scale.

(a)  

Describing rocks or sediments containing particles that are silt- or clay-sized, less than 0.625 mm in size. Most have

a high clay-mineral content, and many contain a sufficient percentage of organic material to be considered a

source rock for hydrocarbon.

(a)  

A solid or nearly solid form of bitumen that can melt upon heating and contains impurities such as nitrogen,

oxygen and sulfur. Asphalt forms naturally when the light components or volatiles of petroleum have been

removed or evaporated.

(a)  

The relatively plastic layer of the upper mantle of the Earth on which the tectonic plates of the lithosphere move.

The asthenosphere is approximately 200 km [124 miles] thick and, owing to its depth below the Earth's surface,

warm (~ 1400 o

C) [2640 o

F] but not molten. Here the mantle deforms by plastic flow in response to applied

pressures above 100 MPa [14,500 psi]. This zone is considered coincidental, at least below oceanic crust, with the

low-velocity zone of the upper mantle.

(a)  

The orientation of a planar or linear feature in three-dimensional space. Planar features that are not horizontal,

such as tilted strata, are described by their strike, or the azimuth of the intersection of the plane with a horizontal

surface, and the dip, or the magnitude of its inclination from a horizontal reference. The trend and plunge of linear

features, such as the axis of a fold, describe the azimuth of the line and its deviation from horizontal.

(a)  

In plate tectonics, a failed rift arm. At the junctions of tectonic plates, three intersecting lithospheric plates

typically are separated by "arms." Arms might be areas of rifting, convergence or transform faults (similar to a

strike-slip fault). The arm along which the motion that spreads the plates apart ceases is termed the failed arm, or

(a)  

Pertaining to minerals or materials that grow in place with a rock, rather than having been transported and

deposited. These include quartz, chlorite and other pore-filling minerals or cements that grow during diagenesis.

Evaporite minerals are authigenic, or formed in situ.

(a)  

Materials, especially rock masses, that formed in their present location and have not been transported. Fault

surfaces can separate indigenous rocks from allochthonous rocks, although some allochthonous rocks are clearly

delineated by their differing composition.

(a)  

In folded rocks, the imaginary surface bisecting the limbs of the fold. The axial surface is called the axial plane

when the fold is symmetrical and the lines defined by the points of maximum curvature of each folded layer, or

hinge lines, are coplanar

(a)  

. n. [Geology]

The angle between the vertical projection of a line of interest onto a horizontal surface and true north or magnetic

north measured in a horizontal plane, typically measured clockwise from north.

See: attitude, dip, strike, trend

2. n. [Drilling]

The compass direction of a directional survey or of the wellbore as planned or measured by a directional survey.

The azimuth is usually specified in degrees with respect to the geographic or magnetic north pole.

See: directional drilling, inclination, survey

3. n. [Reservoir Characterization]

The angle that characterizes a direction or vector relative to a reference direction (usually True North) on a

horizontal plane. The azimuth is usually quoted in degrees from 0 to 359.

4. n. [Drilling, Shale Gas]

The direction in which a deviated or horizontal well is drilled relative to magnetic north. Most horizontal wells in

shale reservoirs are drilled in the direction of the minimum horizontal stress. This allows for the creation of

multiple hydraulic fractures that are normal to the wellbore.

(a)  

Pertaining to being focused in one direction. An azimuthal, or azimuthally focused, measurement has one or more

directions perpendicular to the surface of a logging tool from which it receives most of its signal. Examples are the

density, laterolog and microresistivity logs. A nonazimuthal, or azimuthally symmetric measurement is one which measures equally in all directions around the tool. Examples are the induction, propagation resistivity log and

gamma ray.

See: azimuthal density, azimuthal laterolog, logging tool

2. adj. [Geology]

Pertaining to the angle between the vertical projection of a line of interest onto a horizontal surface and true north

or magnetic north measured in a horizontal plane, typically measured clockwise from north.

(a)  

1. n. [Geology] [BaSO4] A dense sulfate mineral that can occur in a variety of rocks, including limestone and sandstone, with a range of accessory minerals, such as quartz, chert, dolomite, calcite, siderite and metal sulfides. Barite is commonly used to add weight to drilling fluid. Barite is of significance to petrophysicists because excess barite can require a correction factor in some well log measurements. Alternate Form: baryte 2. n. [Drilling Fluids] A dense mineral comprising barium sulfate [BaSO4]. Commonly used as a weighting agent for all types of drilling fluids, barites are mined in many areas worldwide and shipped as ore to grinding plants in strategic locations, where API specifies grinding to a particle size of 3 to74 microns. Pure barium sulfate has a specific gravity of 4.50 g/cm3 , but drilling-grade barite is expected to have a specific gravity of at least 4.20 g/cm3 to meet API specifications. Contaminants in barite, such as cement, siderite, pyrrhotite, gypsum and anhydrite, can cause problems in certain mud systems and should be evaluated in any quality assurance program for drilling-mud additives

(a)  

A map on which primary data and interpretations can be plotted. A base map typically includes locations of lease or concession boundaries, wells, seismic survey points and other cultural data such as buildings and roads, with a geographic reference such as latitude and longitude or Universal Transverse Mercator (UTM) grid information. Geologists use topographic maps as base maps for construction of surface geologic maps. Geophysicists typically use shot point maps, which show the orientations of seismic lines and the specific points at which seismic data were acquired, to display interpretations of seismic data. In the field, geologists can use a plane table and alidade to construct a base map

(a)  

The rock layer below which economic hydrocarbon reservoirs are not expected to be found, sometimes called economic basement. Basement is usually older, deformed igneous or metamorphic rocks, which seldom develops the porosity and permeability necessary to serve as a hydrocarbon reservoir, and below which sedimentary rocks are not common. Basement rocks typically have different density, acoustic velocity, and magnetic properties from overlying rocks

(a)  

A depression in the crust of the Earth, caused by plate tectonic activity and subsidence, in which sediments accumulate. Sedimentary basins vary from bowl-shaped to elongated troughs. Basins can be bounded by faults. Rift basins are commonly symmetrical; basins along continental margins tend to be asymmetrical. If rich hydrocarbon source rocks occur in combination with appropriate depth and duration of burial, then a petroleum system can develop within the basin. Most basins contain some amount of shale, thus providing opportunities for shale gas exploration and production.

(a)  

Pertaining to the environment of deposition and the organisms of the ocean between depths of 200 m [656 ft], the edge of the continental shelf, and 2000 m [6560 ft]. The bathyal environment is intermediate between the neritic environment and the abyss

(a)  

A layer of sediment or sedimentary rock, or stratum. A bed is the smallest stratigraphic unit, generally a centimeter or more in thickness. To be labeled a bed, the stratum must be distinguishable from adjacent beds. See: bed thickness, competent, dipping bed, lamination, progradation, retrogradation, sediment, strike, superposition, true stratigraphic thickness, true vertical thickness

(a)  

The thickness of a layer or stratum of sedimentary rock measured perpendicular to its lateral extent, presuming deposition on a horizontal surface. Because sediment deposition can occur on inclined surfaces, apparent or measured bed thickness might differ from true bed thickness. The thickness of a given bed often varies along its extent.

(a)  

Solid rock either exposed at the surface or situated below surface soil, unconsolidated sediments and weathered rock.

(a)  

A zone of the upper mantle in which earthquakes occur when a lithospheric plate is subducted, named in honor of seismologists Kiyoo Wadati and Hugo Benioff. The dip of this zone, also referred to as the Wadati-Benioff zone, coincides with the dip of the subducting plate. The Wadati-Benioff zone extends to a depth of about 700 km [435 miles] from the Earth's surface

(a)  

Pertaining to the environment and conditions of organisms living at the water bottom, or benthos. Also called benthonic.

(a)  

Organisms that live at the bottom of a body of water

(a)  

A material composed of clay minerals, predominantly montmorillonite with minor amounts of other smectite group minerals, commonly used in drilling mud. Bentonite swells considerably when exposed to water, making it ideal for protecting formations from invasion by drilling fluids. Montmorillonite forms when basic rocks such as volcanic ash in marine basins are altered

2. n. [Drilling Fluids] A clay mineral that is composed principally of three-layer clays, such as montmorillonite, and widely used as a mud additive for viscosity and filtration control. Commercial bentonite ores vary widely in amount and quality of the swelling clay, sodium montmorillonite. Ores of lower quality, those with more calcium-type montmorillonite, are treated during grinding by adding one or more of the following: sodium carbonate, long-chain synthetic polymers, carboxymethylcellulose (CMC), starch or polyphosphates. These help make the final product meet quality specifications. Unfortunately, the additives may not remain effective in "the real mud world" when in use at the rig due to hardness ions in the water, high temperature, bacterial attack, mechanical shear-degradation and other factors that can render these additives ineffective

(a)  

elucidate Earth history, combining the principles of paleontology and stratigraphy. In the petroleum industry, biostratigraphy often denotes the use of terrestrial (pollen and spores) and marine (diatoms, foraminifera, nannofossils) microfossils to determine the absolute or relative age and depositional environment of a particular formation, source rock or reservoir of interest

(a)  

The application of plant and animal fossils to date and correlate strata in order to elucidate Earth history, combining the principles of paleontology and stratigraphy. In the petroleum industry, biostratigraphy often denotes the use of terrestrial (pollen and spores) and marine (diatoms, foraminifera, nannofossils) microfossils to determine the absolute or relative age and depositional environment of a particular formation, source rock or reservoir of interest

(a)  

Naturally-occurring, inflammable organic matter formed from kerogen in the process of petroleum generation that is soluble in carbon bisulfide. Bitumen includes hydrocarbons such as asphalt and mineral wax. Typically solid or nearly so, brown or black, bitumen has a distinctive petroliferous odor. Laboratory dissolution with organic solvents allows determination of the amount of bitumen in samples, an assessment of source rock richness. See: asphalt, generation, geochemistry, hydrocarbon, kerogen, petroleum, petroleum system, source rock, tar sand 2. n. [Heavy Oil] A designation for a hydrocarbon fluid with a gravity of 10° API or lower, based upon the classification of the US Department of Energy. Synonyms: ultra heavy oil 3. n. [Shale Gas] The fraction of naturally occurring, inflammable organic matter that is extractable from rock using organic solvents. Many petroleum precursors are composed of bitumen, but most are formed from kerogen in the process of petroleum generation. Bitumen includes hydrocarbons such as asphalt and mineral wax. Typically solid or nearly so, brown or black, bitumen has a distinctive petroliferous odor. Laboratory dissolution with organic solvents allows determination of the amount of bitumen in samples, an assessment of source rock richness. Burial and heating of kerogen yield bitumen, then liquid hydrocarbons, and then hydrocarbon gas. Understanding organic content is especially important in shale reservoirs because the shale is both the source rock and the reservoir rock in the petroleum system.

(a)  

A characteristic sequence of sedimentary structures occurring in sedimentary rocks deposited in areas of deep water sedimentation by turbidity currents, which form deposits called turbidites. In theory, a complete Bouma sequence comprises sediments that fine upwards, consisting of a lowermost layer of coarse, chaotic clastic sediments deposited under conditions of high depositional energy overlain by successively finer grained and better stratified sediments like sands and muds deposited under calmer conditions that are labeled as Units A though E. In practice, however, the chaotic, high-energy nature of turbidite deposition can alter or remove underlying sediments so that incomplete sequences of sediments typically remain preserved

(a)  

1. n. [Geology] Water containing more dissolved inorganic salt than typical seawater. See: connate water, formation water, fresh water, interstitial water 2. n. [Drilling] Saline liquid usually used in completion operations and, increasingly, when penetrating a pay zone. Brines are preferred because they have higher densities than fresh water but lack solid particles that might damage producible formations. Classes of brines include chloride brines (calcium and sodium), bromides and formates. See: aquifer, completion fluid, producing formation 3. n. [Drilling Fluids] A general term that refers to various salts and salt mixtures dissolved in an aqueous solution. Brine can be used more strictly, however, to refer to solutions of sodium chloride. We prefer to use brine as a general term. The emulsified calcium chloride [CaCl2] solution (or any other saline phase) in an oil mud is referred to as "brine" or "brine phase." The oil/brine ratio, abbreviated OBR, is used to compare solids content and salinities of oil muds. Clear brines are salt solutions that have few or no suspended solids.

(a)  

[CaCO3]The crystalline form of calcium carbonate and chief constituent of limestone and chalk. Calcite reacts readily with dilute hydrochloric acid [HCl], so the presence of calcite can be tested by simply placing a drop of acid on a rock specimen.

(a)  

A crust of coarse sediments or weathered soil rich in calcium carbonate. It forms when lime-rich groundwater rises to the surface by capillary action and evaporates into a crumbly powder, forming a tough, indurated sheet called calcrete

(a)  

A relatively impermeable rock, commonly shale, anhydrite or salt, that forms a barrier or seal above and around reservoir rock so that fluids cannot migrate beyond the reservoir. It is often found atop a salt dome.

(a)  

A class of sedimentary rock whose chief mineral constituents (95% or more) are calcite and aragonite (both CaCo3) and dolomite [CaMg(CO3)2], a mineral that can replace calcite during the process of dolomitization. Limestone, dolostone or dolomite, and chalk are carbonate rocks

(a)  

A type of metamorphic rock with shearing and granulation of minerals caused by high mechanical stress during faulting or dynamic metamorphism, typically during episodes of plate tectonic activity.

(a)  

Pertaining to a type of metamorphic rock with shearing and granulation of minerals caused by high mechanical stress during faulting or dynamic metamorphism, typically during episodes of plate tectonic activity.

(a)  

The physical and chemical alteration of sediments and pore fluids at temperatures and pressures higher than those of diagenesis.

(a)  

Abbreviation for coalbed methane. Natural gas, predominantly methane [CH4], generated during coal formation and adsorbed in coal. Natural gas adsorbs to the surfaces of matrix pores within the coal and natural fractures, or cleats, as reservoir pressure increases. Production of natural gas from coal requires decreasing the pore pressure below the coal’s desorption pressure so that methane will desorb from surfaces, diffuse through the coal matrix and become free gas. Because the diffusivity and permeability of the coal matrix are ultralow, coal must have an extensive cleat

(a)  

The binding material in sedimentary rocks that precipitates between grains from pore fluids. Calcite and quartz are common cement-forming minerals.

The material used to permanently seal annular spaces between casing and borehole walls.

(a)  

The process of precipitation of cement between mineral or rock grains and forming solid clastic sedimentary rock, one phase of lithification

(a)  

A porous marine limestone composed of fine-grained remains of microorganisms with calcite shells, coccolithophores, such as the White Cliffs of Dover (UK)

(a)  

A linear, commonly concave-based depression through which water and sediment flow and into which sediment can be deposited in distinctive, often elongated bodies

(a)  

A sedimentary rock and a variety of quartz made of extremely fine-grained, or cryptocrystalline, silica, also called chalcedony. The silica might be of organic origin, such as from the internal structures of sponges called spicules, or inorganic origin, such as precipitation from solution. The latter results in the formation of flint. Chert can form beds, but is more common as nodules in carbonate rocks.

(a)  

Containing chert, a sedimentary rock and a variety of quartz made of extremely fine-grained, or cryptocrystalline, silica, also called chalcedony. The silica might be of organic origin, such as from the internal structures of sponges called spicules, or inorganic origin, such as precipitation from solution. The latter results in the formation of flint

(a)  

] A platy, pale green mineral of the mica group of sheet silicates, also considered to be a type of clay mineral, found in sedimentary and low-grade metamorphic rocks

(a)  

A graphic display, with geologic time along the vertical axis and distance along the horizontal axis, to demonstrate the relative ages and geographic extent of strata or stratigraphic units in a given area, also known as a Wheeler diagram. In addition, information from seismic data, well logs and rock samples, and biostratigraphic and lithostratigraphic information can be shown within each chronostratigraphic unit.

(a)  

The study of the ages of strata. The comparison, or correlation, of separated strata can include study of their relative or absolute ages

(a)  

The value of the separation between two adjacent contours. A net pay isopach map might have a contour interval of 10 feet [3 m], whereas a structure contour map might have a contour interval of 1000 feet [300 m]. Contour intervals are chosen according to the map scale and the amount and distribution of control points.

(a)  

Structures formed by sediment injection. Because they resemble intrusive and extrusive igneous features, much of the vocabulary for describing clastic intrusions, or injectites, comes from igneous geology. Sills are emplaced parallel to bedding, whereas dikes cut through bedding. The strata containing the intrusion are called host strata and the layers that feed the intrusion are the parent beds. Sand-injection features exhibit size scales from millimeters to kilometers, and have been seen in cores, borehole image logs, seismic sections, outcrops, aerial photographs and satellite images.

(a)  

Sediment consisting of broken fragments derived from preexisting rocks and transported elsewhere and redeposited before forming another rock. Examples of common clastic sedimentary rocks include siliciclastic rocks such as conglomerate, sandstone, siltstone and shale. Carbonate rocks can also be broken and reworked to form clastic sedimentary rocks

(a)