Siltstone vs shale

March 15, 2021. by Hasa. 4 min read. The main difference between sandstone and shale is that sandstone is a sedimentary rock mainly made of sand or quartz grains, while shale is a finely stratified sedimentary rock of silt and clay-size mineral particles. Sedimentary rocks are a type of rocks that form via accumulation or deposition of sediment ...

Siltstone vs shale. The way shaliness affects a log reading depends on the amount of shale and its physical properties. It may also depend on the way the shale is distributed in the formation. Shaly material can be distributed in the formation in three ways: Shale can exist in the form of laminae between which are layers of sand.

Tendency to chemical cement. Ash: unconsolidated fragments under. 4 mm. Tuff: consolidated ash. Volcanic Breccia: angular fragments over 4 mm. Agglomerate: large proportion (>25%) of bombs. These rocks are classified on the proportions of vitric, crystal (mineral), or lithic material they contain, for example, "vitric lithic ash," or "crystal ...

Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud." This composition places shale in a category of sedimentary rocks known as " mudstones ." Shale is distinguished from other mudstones because it is fissile and laminated.Mudstone: indurated mud; includes claystone and siltstone Shale: finely fissile; may include much silt Clay Shale (Argillaceous shale): chiefly clay minerals Argillite: highly indurated; …Sedimentary rocks are commonly grouped according to whether they are clastic, biochemical, or chemical. This works fine, except that it is not clear whether some limestones are biochemical or chemical, and it is not clear where to put dolostone, which is a common rock that often seems to have formed as a result of post-burial chemical alteration of limestone.Claystone, hardened clay. Some geologists further restrict the term to a sedimentary rock that is composed primarily of clay-sized particles (less than 1256 millimetre in diameter) and is not laminated or easily split into thin layers; such rocks that show cleavage roughly parallel to the bedding.Peat Rock Salt (halite) Sandstone Shale Siltstone. Basic Classification - Method of Origin. Clastic. Breccia Conglomerate Sandstone Shale Siltstone. Chemical. Chert Dolomite Gypsum Halite (rock salt) Limestone - micrite Limestone - oolitic Limestone - intraclastic Rock Salt (halite) Biochemical. Chalk Coal - bituminous Coal - anthracite Coquina ...

The common names of clastic sedimentary rocks—conglomerate, sandstone, siltstone, and shale—are based solely on grain size. However, there are more precise names within these broader categories that are based on clastic sediment features other than grain size. Breccia is a clastic sedimentary rock distinguished from conglomerate by the ...Siltstone can be almost any color but is usually tan, brown, or reddish in color. Siltstone is an intermediate clastic rock between sandstone and shale, but it not as common as either. It doesn’t usually display visible layers, and will almost never break along bedding planes.The streak of Mudstone and Shale is white. The specific heat capacity of Mudstone is 0.39 kJ/Kg K and that of Shale is 0.39 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Mudstone is heat resistant, impact resistant whereas Shale is heat ...Siltstone, hardened sedimentary rock that is composed primarily of angular silt-sized particles (0.0039 to 0.063 mm [0.00015 to 0.0025 inch] in diameter) and is not laminated or easily split into thin layers. Siltstones, which are hard and durable, occur in thin layers rarely thick enough to be.The only difference between mudstone and shale is that mudstones break into blocky pieces whereas shales break into thin chips with roughly parallel tops and bottoms. Both …As nouns the difference between silt and shale is that silt is while shale is...claystone, hardened clay.Some geologists further restrict the term to a sedimentary rock that is composed primarily of clay-sized particles (less than 1 / 256 millimetre in diameter) and is not laminated or easily split into thin layers; such rocks that show cleavage roughly parallel to the bedding plane often are classed as clay shales. Claystones that are …

Marl Scala dei Turchi coastal marl formation, southern Sicily. Marl is an earthy material rich in carbonate minerals, clays, and silt.When hardened into rock, this becomes marlstone.It is formed in marine or freshwater environments, often through the activities of algae.. Marl makes up the lower part of the cliffs of Dover, and the Channel Tunnel follows these marl …All. 1 Definition. 1.1 Definition. Siltstone can be defined as a fine-grained sedimentary rock which mainly consists of consolidated silt. Mudstone is a fine-grained, dark gray sedimentary rock, which is formed from silt and clay and is similar to shale but has less laminations. 1.2 History. Study with Quizlet and memorize flashcards containing terms like What are the 3 main types of sedimentary rocks?, List from smallest to largest: What is the difference among a sandstone, siltstone and shale?, What is the difference between a breccia and conglomerate? In what environment do you find each type? and more.Slate, schist, and gneiss are three common foliated metamorphic rocks. Slate is a hard, fine-grained rock with a well-developed rock cleavage or slaty cleavage caused by the incipient growth of platy (micaceous) minerals, due to metamorphism of fine-grained clastic sediments such as shale and siltstone and also volcanic tuffs.l) The Waterford Formation, consists of fine- to medium-grained sandstone, siltstone, shale and rhythmite. The lower part of the Formation is characterized by upward-coarsening cycles of sediments, which are capped by extensive sheet-like sandstones and alternating chaotic, slump and slide deposits.

Ba dance.

Mudstone. Mudstone or mudrock, previously and more commonly termed shale, can form thick intervals in deepwater settings, ranging from several cm to kilometers in thickness ( Potter et al., 2005 ). Mudstone consists of a variety of types, and this heterogeneity is outlined in Boulesteix et al. (2020); principally by mudstone that is derived ...For the siltstone specimens under test, the bedding plane has a stronger influence on the permeability, up to three times difference between the permeability of PB specimen and NB specimen under the same loading level (Fig. 5b). Generally, the permeability of the siltstone specimens in the parallel direction are substantially higher …Sedimentary rocks are commonly grouped according to whether they are clastic, biochemical, or chemical. This works fine, except that it is not clear whether some limestones are biochemical or chemical, and it is not clear where to put dolostone, which is a common rock that often seems to have formed as a result of post-burial chemical alteration of limestone.Shales are fine-grained sedimentary rocks composed of clay, silt, and, in some cases, fine sand. Shale types range from clay-rich gumbo (relatively weak) to shaly siltstone (highly cemented), and have in common the characteristics of extremely low permeability and a high proportion of clay minerals.

The fine-grained deposits of Chang 7 Member in Ordos Basin are composed of five lithologies: fine sandstone, siltstone, black shale, dark mudstone, and tuff, with shale as the major part, interbedded with many thin layers of fine siltstone . The Chang 7 Member has a porosity of 9%~15% and a permeability of 0.01~1.0 mD, which is a well-developed ...Fine-grained rocks include mudstone, shale, siltstone, and claystone. Mudstone is a general term for rocks made of sediment grains smaller than sand (less than 2 mm). Rocks that are fissile, meaning they separate into thin sheets, are called shale. Rocks exclusively composed of silt or clay sediment, are called siltstone or claystone ...Mudstone: indurated mud; includes claystone and siltstone Shale: finely fissile; may include much silt Clay Shale (Argillaceous shale): chiefly clay minerals Argillite: highly indurated; …Shale. Shale is a very fine-grained, clastic sedimentary rock which is made up mostly of clay (defined as particles smaller than 1/256 mm) and which is fissile (tending to break along natural laminations, or planes of weakness, that are less than 1 cm thick). Generally, shale occurs in thin layers or beds and represent low-energy environments ...Shale is available in black, brown, buff, green, grey, red, yellow colors whereas, Siltstone is available in brown, red, reddish brown colors. Appearance of Shale is Muddy and that of Siltstone is Rough. Properties of rock is another aspect for Shale vs Siltstone. The hardness of Shale is 3 and that of Siltstone is 6-7.siltstone: shale * Jump Up to Sedimentary Topics Listing * Sedimentary Structures and Fossils--things found in sedimentary rocks . Stratification - horizontal layering at time of deposition ; Ripple Marks - undulatory structures due to wind/water current ; Cross Bedding - internal angular layering within a horizontal bed (due to ripple mark ...March 15, 2021. by Hasa. 4 min read. The main difference between sandstone and shale is that sandstone is a sedimentary rock mainly made of sand or quartz grains, while shale is a finely stratified sedimentary …Siltstone, an abundant sedimentary rock type that is probably more prevalent on the landscape than shale, is often misidentified and labeled as shale by engineers. The mechanical properties of siltstone make siltstone an important class from an engineering/rock strength standpoint as well.Slate, schist, and gneiss are three common foliated metamorphic rocks. Slate is a hard, fine-grained rock with a well-developed rock cleavage or slaty cleavage caused by the incipient growth of platy (micaceous) …Taking Well YQ56 (Fig. 13) as an example, the reservoir-controlled shale gas enrichment section is between 3099.8 m and 3123.2 m, with a cumulative thickness of 21.4 m, an average TOC of 1.97%, and a lithology is mainly composed of dark gray shale intercalated with light gray argillaceous siltstone and siltstone. This area also has three ...The siltstone and muddy-siltstone do not exhibit fracture pores observed in silty-shales, indicating that they do not have the laminar fabrics of shale due to the increase in siliciclastic input. In order to recognize the vertical variations of the samples petrophysical properties determined from the PSD measurements, a compiled plot of the ...

The streak of Slate is light to dark brown while that of Shale is white. The specific heat capacity of Slate is 0.76 kJ/Kg K and that of Shale is 0.39 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Slate is heat resistant, impact resistant ...

Interbedded between siltstone and mudstone is more frequency within the FA2 in the first cycle than in the second cycle. This may suggest that the variation in depositional conditions during the first cycle is higher than in the second cycle. ... Lacustrine shales of the Huai Hin Lat Formation have been recognized as one of potential source ...Sedimentary rocks are commonly grouped according to whether they are clastic, biochemical, or chemical. This works fine, except that it is not clear whether some limestones are biochemical or chemical, and it is not clear where to put dolostone, which is a common rock that often seems to have formed as a result of post-burial chemical alteration of limestone.actually predominantly a mudstone/shale or a siltstone. This can only be resolved by sampling and grain size analysis. Should any conflict arise it is recommended that the division at 63 µm be used as this is widely recognised. Shale, mudstone and slate are collectively referred to as ‘mudrocks’ and are the most abundantShale is a very fine-grained, clastic sedimentary rock which is made up mostly of clay (defined as particles smaller than 1/256 mm) and which is fissile (tending to break along natural laminations, or planes of weakness, that are less than 1 cm thick). Generally, shale occurs in thin layers or beds and represent low-energy environments such as: offshore deposits of mud in ancient …Shale is a laminated or fissile clastic sedimentary rock that composed of predominance of silt and clay other minerals , especially quartz and calcite. Characteristic properties of shale is breaks along thin laminae or parallel layering or bedding called fissility. It is most abundant sedimentary rock. The composition (silt and clay) of shale ...In conglomerate, the stones are rounded. In breccia, the stones are angular. Sandstone is made of sand-sized particles. Siltstone is made of smaller particles. Silt is smaller than sand but larger than clay. Shale has the smallest grain size. Shale is made mostly of clay-sized particles and hardened mud.Advertisement Although siltstone and shale are similarly formed in water, identifying siltstone and shale requires distinguishing between silt and clay particles. … 002 inches) and larger than clay-size particles, which are smaller than . 004 millimeters in diameter (. 0002 inches). What does shale look like? Shales are typically composedRead More →Shale is a laminated or fissile clastic sedimentary rock that composed of predominance of silt and clay other minerals , especially quartz and calcite. Characteristic properties of shale is breaks along thin laminae or parallel layering or bedding called fissility. It is most abundant sedimentary rock. The composition (silt and clay) of shale ...

Group conformity.

At what level of service are evaluation plans designed.

Hydrocarbon source potential of tertiary carbonaceous shale, shale and siltstone of eastern Chenor, Penyu basins, Pahang, Malaysia ... versus TOC content ...Deepwater Geology & Geoscience Peter Aird, in Deepwater Drilling, 2019 Siltstone A siltstone is a lithified, nonfissile mudrock. In order for a rock to be named a siltstone, it …The Pierre Shale and equivalent rocks of Late Cretaceous age consist in the east-central Dakotas of several hundred feet of offshore-marine shale and minor marl; in west-central Montana near the sediment source the equivalents of the Pierre Shale consist of several thousand feet of volcanic-rich and mostly nonmarine sediments; and in the area between, both types of rock are separated by tongues of (2) Tight oil, similar to tight gas, is a petroleum resource produced from ultra-low permeability shale, siltstone, sandstone, and carbonate, which are closely related to oil-source shales. This resource is defined as “light tight oil” by IEA and “tight oil” by Statoil, EIA, and some Chinese scholars (EIA 2011 ; Zou et al. 2012 ).Correlation between UCS and PLI for shale specimens. ... [41] conducted a series of point load tests on the samples of red bed siltstone with different shapes (cylinder, square, and irregular ...Bringelly Shale Top most unit, comprising of: claystone, carbonaceous claystone, siltstone, laminite, sandstone and tuff. Maximum thickness of less than 250 m. Minchinbury Sandstone Quartz-lithic, fine to medium grained quartz lithic sandstone, separating the underlying Ashfield shale from overlying Bringelly shale; Thickness of up to 6 m.Tendency to chemical cement. Ash: unconsolidated fragments under. 4 mm. Tuff: consolidated ash. Volcanic Breccia: angular fragments over 4 mm. Agglomerate: large proportion (>25%) of bombs. These rocks are classified on the proportions of vitric, crystal (mineral), or lithic material they contain, for example, "vitric lithic ash," or "crystal ...Siltstone is a sedimentary rock composed mainly of silt-sized particles. It forms where water, wind, or ice deposit silt, and the silt is then compacted and cemented into a rock. Silt accumulates in sedimentary basins throughout the world. It represents a level of current, wave, or wind energy between where sand and mud accumulate.Grey chunks of graptolitic argillite on Pakri Peninsula, Estonia; yellowish and white chunks are limestone. Argillite (/ ˈ ɑːr dʒ ɪ l aɪ t /) is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes.They contain variable amounts of silt-sized particles.The argillites grade into shale …Examine these characteristics on an individual basis to find the distinction between rock salt and rock gypsum. ANSWER: Shale is well sorted, while siltstone is poorly sorted. Because shale has larger grains than siltstone, siltstone …The specific heat capacity of Sandstone is 0.92 kJ/Kg K and that of Shale is 0.39 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Sandstone is heat resistant, impact resistant, pressure resistant whereas Shale is heat resistant, impact resistant. ….

Examine these characteristics on an individual basis to find the distinction between rock salt and rock gypsum. ANSWER: Shale is well sorted, while siltstone is poorly sorted. Because shale has larger grains than siltstone, siltstone …Claystone, hardened clay. Some geologists further restrict the term to a sedimentary rock that is composed primarily of clay-sized particles (less than 1256 millimetre in diameter) and is not laminated or easily split into thin layers; such rocks that show cleavage roughly parallel to the bedding.Siltstone. A siltstone is a lithified, nonfissile mudrock. In order for a rock to be named a siltstone, it must contain over 50% silt-sized material. Silt is any particle smaller than sand, 1/16 of a millimeter, and larger than clay, 1/256 of millimeter. Silt is believed to be the product of physical weathering, which can involve freezing and ... The only difference between mudstone and shale is that mudstones break into blocky pieces whereas shales break into thin chips with roughly parallel tops and bottoms. Both …It also separates shale from siltstone, which is a mudstone in which the silt predominates over clay. Finely laminated shale. Shale is a fine-grained ...applied load, L the length between supports, D th e specimen diameter, a is the beam thickness and, b, is its width. For four point loading (F igure 5b), equation (6) is replaced by the following Note that in general, the tensile strength measured using the indirect methods is less than that measured used a direct tension apparatus. 2.5 Shear TestsChalk is a type of limestone made up of the microscopic calcium carbonate shells of marine organisms. Chalk is soft, friable, porous, and effervesces vigorously in contact with …Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud." This composition places shale in a category of sedimentary rocks known as " mudstones ." Shale is distinguished from other mudstones because it is fissile and laminated. Siltstone vs shale, Thus, identifying the “sweet spots” in shale oil reservoirs is critical for the efficient exploration and development of terrestrial shale oil. This study targets the siltstone type (Class-II shale oil) and pure shale type (Class-III shale oil) of the Chang 7 Member in the Ordos Basin, and identifies three stratigraphic units, namely the ..., The specific heat capacity of Sandstone is 0.92 kJ/Kg K and that of Siltstone is Not Available. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Sandstone is heat resistant, impact resistant, pressure resistant whereas Siltstone is heat resistant, impact ..., Shale usually contains about 50% silt, 35% clay, and 15% chemical materials, many shales may also contain organic plant materials and fossils. Shale is characterized by thinly, laminated layers, representing successive deposition of sediments. Shale accounts for about 50% of all sedimentary rocks deposited on the Earth’s surface. , Siltstone has a finer grain than sandstone, but is coarser than claystone. It is often mistaken for shale, though it is missing both fissility (the ability ..., Sandy shales (or siltstones) and sandy fireclays are distinguished from sandstones because they are darker in color, less gritty to the touch and do not have a ..., Shale usually contains about 50% silt, 35% clay, and 15% chemical materials, many shales may also contain organic plant materials and fossils. Shale is characterized by thinly, laminated layers, representing successive deposition of sediments. Shale accounts for about 50% of all sedimentary rocks deposited on the Earth’s surface., Also, because the most basic definition of shales, that they be dominated by particles smaller than 62.5 μm (e.g., Blatt et al., 1980), implies that shales span the clay-silt boundary, a good many rocks that are identified as siltstones in the literature also qualify as shales (and vice versa)., Mar 15, 2021 · March 15, 2021. by Hasa. 4 min read. The main difference between sandstone and shale is that sandstone is a sedimentary rock mainly made of sand or quartz grains, while shale is a finely stratified sedimentary rock of silt and clay-size mineral particles. Sedimentary rocks are a type of rocks that form via accumulation or deposition of sediment ... , Slaking and weathering of weak rocks result in slope instability. Siltstones from flysch rock masses are highly susceptible to weathering, which causes rapid changes in the geotechnical properties and durability. This study investigated siltstone samples of different weathering grades from flysch rock masses from the Istria Peninsula, Croatia, …, Siltstone vs Shale Properties. Properties of Siltstone and Shale play an important role in determining the type of rock. Along with Siltstone vs Shale properties, get to know more about Siltstone Definition and Shale Definition. For the ease of understanding, the properties of rocks are divided into physical and thermal properties., Sandy Shales with Layered or Streaked Structure consist of bands or layers of sandstone interlayered with shale lying in planes at, or nearly at, right angles to the side of the core. Where sandstone makes up between 80% and 20% of the total volume of the rock, the rock is said to be a Shale and Interbedded Sandstone ( e.g. 50L ). , The smallest grains are called clay, then silt, then sand. Grains larger than 2 millimeters are called pebbles. Shale is a rock made mostly of clay, siltstone is made up of silt-sized grains, sandstone is made of sand-sized clasts, and conglomerate is made of pebbles surrounded by a matrix of sand or mud. Biologic Sedimentary Rocks:, Shale is available in black, brown, buff, green, grey, red, yellow colors whereas, Siltstone is available in brown, red, reddish brown colors. Appearance of Shale is Muddy and that of Siltstone is Rough. Properties of rock is another aspect for Shale vs Siltstone. The hardness of Shale is 3 and that of Siltstone is 6-7., Turbidite sequences are classic hosts for lode gold deposits, the prime example being Bendigo and Ballarat in Victoria, Australia, where more than 2,600 tons of gold have been extracted from saddle-reef deposits hosted in shale sequences from a …, Shale is available in black, brown, buff, green, grey, red, yellow colors whereas, Siltstone is available in brown, red, reddish brown colors. Appearance of Shale is Muddy and that of Siltstone is Rough. Properties of rock is another aspect for Shale vs Siltstone. The hardness of Shale is 3 and that of Siltstone is 6-7. , Mudstone, the finest‐grained clastic rock, is not well layered, and contains more clay than does shale or siltstone. Most shales, siltstones, and mudstones are ..., 26 thg 9, 2016 ... Although commonly referred to as shale, source rocks are made up of mudstone and siltstone, with minor fine-grained sandstone, and grain-size ..., Shale gas is a form of natural gas (mostly methane), found underground in shale rock. It is classified as ‘unconventional’ because it is found in shale , a less permeable rock formation than sandstone, siltstone or limestone in which ‘conventional’ gas is found, and it is generally distributed over a much larger area. Shale is a fine ..., Mudrocks include all siliciclastic sedimentary rocks composed of silt- and clay-size particles: siltstone (1 / 16 millimetre to 1 / 256 millimetre diameters), claystone (less than 1 / 256 millimetre), and mudstone (a mix of silt and clay). Shale refers specifically to mudrocks that regularly exhibit lamination or fissility or both., ... siltstone and shale.British. Hơn. Duyệt qua các chữ cái. A · B · C · D · E · F · G · H · I · J · K · L · M · N · O · P · Q &..., The Pierre Shale and equivalent rocks of Late Cretaceous age consist in the east-central Dakotas of several hundred feet of offshore-marine shale and minor marl; in west-central Montana near the sediment source the equivalents of the Pierre Shale consist of several thousand feet of volcanic-rich and mostly nonmarine sediments; and in the area …, Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud." This composition places shale in a category of sedimentary rocks known as " mudstones ." Shale is distinguished from other mudstones because it is fissile and laminated. , Siltstone can be almost any color but is usually tan, brown, or reddish in color. Siltstone is an intermediate clastic rock between sandstone and shale, but it not as common as either. It doesn’t usually display visible layers, and will almost never break along bedding planes., Siltstone (the mineralogy is difficult to distinguish without magnification or laboratory work) Limestone (difficult to distinguish from endogenous types of limestone) Clay Very fine grained Majority of grains less than 1/256 mm. Feels smooth when scratched with fingernail Earthy odor when damp Shale Lithographic Limestone, The Chang 71 and Chang 72 sub-members have combination of fine sandstone, siltstone, black shale and dark mudstone, while the Chang 73 sub-member has the combination of black shale and dark mudstone interbedded with thin silty-fine sandstone (Fig. 10). Thickness of a single sand body is 2–5 m. Multi-stage sand bodies stack over each ..., – siltstone, if they contain more than 2/3 silt over clay – mudstone, when ... Casanova shale. Shales are very fissile and break into flat, parallel chips ..., 3 thg 9, 2015 ... 1st Kind of Rocks Types_of_Rocks 2nd Kind of Rocks. Kinds_of_Rocks. 3rd of all Kinds of Rockshttps://www.youtube.com/watch?v=jPgE74Vltdc., Shale. Shale is a very fine-grained, clastic sedimentary rock which is made up mostly of clay (defined as particles smaller than 1/256 mm) and which is fissile (tending to break along natural laminations, or planes of weakness, that are less than 1 cm thick). Generally, shale occurs in thin layers or beds and represent low-energy environments ..., Silt forms fine-grained siltstone, with fragments between 1/16 mm and 1/256 mm. Anything less than 1/256 mm results in either claystone or mudstone. Two types of mudstone are shale and argillite , which is shale that has undergone very low-grade metamorphism., When we have to compare Siltstone vs Shale, the texture, color and appearance plays an important role in determining the type of rock. Siltstone is available in brown, red, reddish brown colors whereas, Shale is available in black, brown, buff, green, grey, red, yellow colors. Appearance of Siltstone is Rough and that of Shale is Muddy., Compared with marine shale oil systems outside of China that mostly consist of a single lithology and contain concentrated sweet spots of ... pores (well J10014; 3230.65 m). (d) Dolomitic mudstone with intercrystalline pores (well A; 3466.4 m). (e) Dolomitic siltstone containing dissolution and intergranular pores (well J10014; 3242.53 m). ..., Three different types of samples were collected from well 03-21-080-17W6 in the British Columbia portion of the wet-gas (condensate) window of the unconventional Montney tight gas siltstone reservoir., Detrital cycles average 5.2 m (17 ft) thick and consist of basal, argillaceous, very fine grained sandstone to coarse siltstone; medial, dark-gray to black, laminated siltstone, silty mudstone, or silty limestone; and upper, light- to dark-gray, silty to dolomitic or analcime-rich mudstone, argillitic siltstone, or very-fine-grained sandstone.