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13-487: The formation, with a maximum thickness of 126 metres (413 ft), comprises reddish mudstones with thin beds of tuffs and sandstones , deposited in a fluvial , environment . The tuff in the formation is dated to 5.84 ± 0.41 Ma, placing it in the Huayquerian SALMA , the age named after the formation by Kraglievitch in 1934. The formation has provided fossils of the procyonid Cyonasua pascuali and

26-682: A further increase to the upper limit for the matrix size in order to bring it into line with the upper limit for silt (63 μm). On December 13, 2016, NASA reported further evidence supporting habitability on the planet Mars as the Curiosity rover climbed higher, studying younger layers, on Mount Sharp . Also reported, the very soluble element boron was detected for the first time on Mars. In June 2018 , NASA reported that Curiosity had detected kerogen and other complex organic compounds from mudstone rocks approximately 3.5 billion years old. Lithification Lithification (from

39-491: A variety of accessory minerals . In the Dunham classification (Dunham, 1962 ) system of limestones , a mudstone is defined as a mud-supported carbonate rock that contains less than 10% grains. Most recently, this definition has been clarified as a matrix-supported carbonate-dominated rock composed of more than 90% carbonate mud (<63 μm) component . A recent study by Lokier and Al Junaibi (2016) has highlighted that

52-571: 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 NASA Curiosity rover has found deposits of mudstone on Mars that contain organic substances such as propane , benzene and toluene . There

65-412: Is clay particles. Another definition is that mudstone is a sedimentary rock in which neither silt, clay, nor coarser grains is predominant. Rock of this composition that does show laminations or fissility is sometimes described as mudshale rather than mudstone . The lack of fissility or layering in mudstone may be due to either original texture or the disruption of layering by burrowing organisms in

78-556: Is not a single definition of mudstone that has gained general acceptance, though there is wide agreement that mudstones are fine-grained sedimentary rocks, composed mostly of silicate grains with a grain size less than 0.063 millimetres (0.0025 in). Individual grains this size are too small to be distinguished without a microscope, which means that most classifications emphasize texture rather than mineral composition, and mudstones have historically received less attention from petrologists than have sandstones . The simplest definition

91-420: Is that a mudstone is a fine-grained clastic sedimentary rock that is not laminated or fissile . Most definitions also include a requirement that the rock contain significant amounts of both silt- and clay-sized grains. One common requirement is that a mudstone is a mudrock (a rock containing more than 50% silt- to clay-sized particles) in which between a third and two-thirds of the mud (silt and clay) fraction

104-572: The Ancient Greek word lithos meaning 'rock' and the Latin -derived suffix -ific ) is the process in which sediments compact under pressure , expel connate fluids , and gradually become solid rock. Essentially, lithification is a process of porosity destruction through compaction and cementation . Lithification includes all the processes which convert unconsolidated sediments into sedimentary rocks . Petrifaction , though often used as

117-654: The litoptern Huayqueriana cristata , named after the formation. The Huayqueriás Formation, present in the Frontal Cordillera and the neighboring Cuyo Basin , was described in 1934 by Kraglievitch as the basis for the Huayquerian South American land mammal age . The name Huayquerías means "badlands". The formation comprises reddish mudstones with mudcracks , paleoburrows and ichnofossils of vertebrates . Thin sandstone layers of up to 12 centimetres (4.7 in) thick exist in

130-538: The ashfall bed in the formation, provided a much younger age of 5.84 ± 0.41 Ma, extending the temporal range of the Huayquerian SALMAans until near the Miocene-Pliocene limit. The Huayqueriás Formation has provided fossils of Cyonasua pascuali , and the litoptern Huayqueriana cristata , the latter of which, named after the formation. Mudstone Mudstone , a type of mudrock ,

143-427: The formation. An ashfall bed exists at 83 metres (272 ft) below the contact with the slightly angular unconformably overlying Tunuyán Formation in a total section of 126 metres (413 ft). The tuff has been dated using K/Ar analysis to 5.84 ± 0.41 Ma. The Huayquerías Formation has been used to define the Huayquerian South American land mammal age , ranging from 9.0 to 6.8 Ma. However, later analysis of

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156-454: The most common problems encountered when describing a mudstone is to incorrectly estimate the volume of 'grains' in the sample - in consequence, misidentifying mudstone as wackestone and vice versa. The original Dunham classification (1962) defined the matrix as clay and fine-silt size sediment <20 μm in diameter. This definition was redefined by Embry & Klovan (1971 ) to a grain size of less than or equal to 30 μm. Wright (1992 ) proposed

169-486: The sediment prior to lithification . Mudstone looks like hardened clay and, depending upon the circumstances under which it was formed, it may show cracks or fissures, like a sun-baked clay deposit. When the mineral composition of mudstones has been determined, using such techniques as scanning electron microscopy , electron probe microanalysis , or X-ray diffraction analysis , they have been found to be composed primarily of clay minerals , quartz , and feldspars , with

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