siderite concretions

Concretions, nodules and weathering features of the

Concretions, nodules and weathering features of the Carmelo Formation The features that characterize a sedimentary rock can form at Siderite nodules exposed on Weston Beach. Oxidation has caused the exposed surfaces of the iron carbonate that composes the nodules to turn red ("rust").

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SIDERITE (Iron Carbonate)

Other typical habits include the scalahedron, crusts, sphericules, concretions and complied botyroidal masses. Siderite forms mostly in sedimentary and hydrothermal environments, although it is also found in some igneous pegmatites. Siderite is a common mineral although excellent, attractive crystal specimens are sometimes hard to find.

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"Iron concretions in the Cretaceous Dakota Formation" by

The Cretaceous Dakota Formation contains abundant iron oxide concretions. The precursors to the iron concretions are siderite (FeCO3) nodules that formed in a reducing floodplain environment. A variety of concretion morphologies formed when the precursor siderite nodules were dissolved by oxidizing groundwater in a paleoaquifer. Ironoxidizing bacteria are able to oxidize aqueous Fe(II) to Fe

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Magothy Formation (NJKmg1) USGS

The contact is placed at the base of the lowest darkgray clay in the Magothy. The best faunas from the Magothy were obtained from siderite concretions and slabs in and near Cliffwood Beach representing only the top of the formation. These faunas were discussed in detail by Weller (1904, 1907) and supplemented by Sohl (in Owens and others, 1977).

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Concretions DesertUSA

Concretions Composed of a carbonate mineral such as calcite. A concretion is a compact mass of mineral matter, usually spherical or diskshaped, embedded in a host rock of a different composition.

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Morphologic Clues to the Origins of Iron Oxide–Cemented

The oxidation process was mediated by ironoxidizing microbes and began at concretion perimeters when oxidizing groundwater started to displace the CO 2 and methanebearing water that had precipitated the siderite. In contrast, pipelike concretions are centrifugal—rinds formed around a cylindrical reaction front and thickened outward toward

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DISTINCTIVE REMNANTS OF SIDERITE CONCRETIONS OXIDIZED

The iron oxide remaining in the core zones of the larger concretions is pseudomorphous after siderite that was oxidized in situ (i.e. iron that did not diffuse outward to contribute to the rind). Siderite originally formed under reducing conditions within a confined aquifer, downgradient from an anticline charged with CO 2 and CH 4. With

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AAPG Datapages/Archives: Siderite Concretions: Indiors

The Upper Cretaceous Gammon Shale in the northern Great Plains contains abundant siderite concretions that formed during the early compactional history of the finegrained, marine sediments. The relative depth of siderite precipitation can be estimated on the basis of textural, mineralogical, and isotopic evidence.

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Origin of Siderite Concretions In Microenvironments of

They host siderite concretions with δ 13 C values ranging from −3.5 to 12.1‰ which show that sulfate reduction and methanogenesis contributed to the production of bicarbonate. Fossils are found within each of the concretions, suggesting that the decay of these organic remains provided a alyst for concretionary growth.

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Round the Rocks: Curious New Zealand Concretions

''Septarian'' concretions contain an internal network of shrinkage cracks, which widen towards the interior and may be filled with crystals, commonly calcite, sometimes other minerals such as siderite barite or pyrite. Concretions tend to stand out in rock outcrops due to their eyeching shape(s) and erosion resistant nature due to

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Siderite: Mineral information, data and localities.

Calcite Group. MagnesiteSiderite Series, RhodochrositeSiderite Series, SideriteSmithsonite Series. Crystals typically found as brown to tan rhombohedrons in clusters, faces often curved or composites more often found as medium to dark brown massive finegrained material or as massive crystalline material with exposed curved cleavage surfaces.

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Concretions, nodules and weathering features of the

Concretions, nodules and weathering features of the Carmelo Formation The features that characterize a sedimentary rock can form at Siderite nodules exposed on Weston Beach. Oxidation has caused the exposed surfaces of the iron carbonate that composes the nodules to turn red ("rust").

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SIDERITE CONCRETIONS IN THE COPAN CRINOID LAGERSTÄTTE

SIDERITE CONCRETIONS IN THE COPAN CRINOID LAGERSTÄTTE Palaios

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Mazon Creek Formation Fossils Virtual Museum of Geology

Most fossils are found in concretions (siderite nodules) along the Mazon River area of the Illinois counties of Grundy, Will, Kankakee, Livingston and LaSalle, and are recovered from formation exposures along the river and nearby streams, roadcuts and within waste piles of abandoned and active coal mines.

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Geolex — Gammon publiions Geologic map

Named as basal member of Pierre shale for exposures along Gammon Creek, T57N, Rs67 and 68W, Crook Co, WY in the Powder River basin. Consists of lightgray mudstone and shale containing abundant ironstained concretions and thin beds of siderite.

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Stable isotope geochemistry of siderite concretions from

The diagenetic history of siderite concretions in Mesozoic sedimentary rocks on the island of Bornholm has been investigated using stable isotope, AAS and XRDanalysis and determination of carbonate content. Siderite concretions and bands, found in nonmarine as

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Mazon Creek Formation Fossils Virtual Museum of Geology

Most fossils are found in concretions (siderite nodules) along the Mazon River area of the Illinois counties of Grundy, Will, Kankakee, Livingston and LaSalle, and are recovered from formation exposures along the river and nearby streams, roadcuts and within waste piles of abandoned and active coal mines.

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DISTINCTIVE REMNANTS OF SIDERITE CONCRETIONS OXIDIZED

The iron oxide remaining in the core zones of the larger concretions is pseudomorphous after siderite that was oxidized in situ (i.e. iron that did not diffuse outward to contribute to the rind). Siderite originally formed under reducing conditions within a confined aquifer, downgradient from an anticline charged with CO 2 and CH 4. With

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North Dakota Geologic Survey

North Dakota, especially in the wondrously sculpted badland areas of the west, has a fantastic variety of concretions and nodules. Some are the size and shape of petrified logs, while others, perched atop pedestals of softer sediments that they shield from erosion, have lens or disk shapes.

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Feoxide concretions formed by interacting carbonate and

The siderite concretion undergoes oxidative dissolution, which is possibly microbially mediated and which provides an internal source of Fe that forms an Feoxide crust on the outside the concretion. However, a problem with this model is that no siderite concretions have been identified, neither in outcrop (6, 8, 9) nor in any deeper

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Siderite an overview ScienceDirect Topics

The siderite concretions occur only in the lower 3–5 m (c. 10–15 ft) of the member, and only where the shale is more than 15 m (c. 50 ft) thick. The shale is coarser and bears sandstones near its top. The Mecca Quarry Shale is a typical Pennsylvanian black shale,

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SIDERITE CONCRETIONS IN THE COPAN CRINOID LAGERSTÄTTE

SIDERITE CONCRETIONS IN THE COPAN CRINOID LAGERSTÄTTE Palaios

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DISTINCTIVE REMNANTS OF SIDERITE CONCRETIONS OXIDIZED

The iron oxide remaining in the core zones of the larger concretions is pseudomorphous after siderite that was oxidized in situ (i.e. iron that did not diffuse outward to contribute to the rind). Siderite originally formed under reducing conditions within a confined aquifer, downgradient from an anticline charged with CO 2 and CH 4. With

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Fossil egg or turtle shell, Kentucky Geological Survey

Siderite is another type of mineral that forms concretions. It is common throughout Kentucky. Generally siderite forms red, orange, or brown concretions, from inches to a foot in length. Some concretions are oval to circular. Others have irregular shapes that may look like horns, teeth, or claws.

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(PDF) Siderite concretions from nonmarine shales

PDF Backstered electron microscopy has been used to examine the microstructure of nonmarineshalehosted siderite concretions. The concretions are

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Siderite concretions: indiors of early diagenesis in

The Gammon member of the Pierre shale of the northern Great Plains, USA, contains abundant siderite concretions. The relative depth and time of siderite precipitation can be inferred from the structure, mineralogy and isotopic composition of these concretions. Concretions that formed at shallow depths, early in the history of the sediment, contain a high percentage (7585%) of carbonate

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Siderite concretion horizon above the No. 22 Coal Seam in

Siderite concretion horizons are known both from the paralic and terrestrial sediments of the Upper Silesian Basin. Significant horizon above the No. 22 Coal Seam in the Upper Suchá Member of Karviná Fm. (Westphalian, Pennsylvanian) was investigated by

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What Is a Septarian Concretion? Geology In

A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Septarian concretions are concretions containing angular cavities or cracks, called "septaria". The septaria are the calcite

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Siderite concretions indiors of early diagenesis in

The Upper Cretaceous Gammon Shale in the northern Great Plains contains abundant siderite concretions that formed during the early compactional history of the finegrained, marine sediments. The relative depth of siderite precipitation can be estimated on the basis of textural, mineralogical, and isotopic evidence.

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THE OCCURRENCE AND ORIGIN OF SIDERITE CONCRETIONS IN

MAZON CREEK FOSSILS THE OCCURRENCE AND ORIGIN OF SIDERITE CONCRETIONS IN THE FRANCIS CREEK SHALE (PENNSYLVANIAN) OF NORTHEASTERN ILLINOIS Bertram G. Woodland Curator of Petrology Field Museum of Natural History Chicago, Illinois Richard C. Stenstrom Department of Geology Beloit College Beloit, Wisconsin ABSTRACT Siderite concretions are well known from

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Wooster''s Fossil of the Week: A crinoidrich Lower

Jan 05, 2014 · The decay of their soft parts produced hydrogen sulfide gas ad carbon dioxide, triggering the geochemistry that caused the precipitation of siderite around them. The hard concretion that resulted was likely in a matrix of soft shale. The strength of the siderite kept the fossils from being crushed by the weight of sediment above.

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Isotopic Study of Siderite Concretion, Tuscarawas County, Ohio

A carbonate concretion from the shale bed overlying the No. 5 coal of Pennsylvanian age in Tuscarawas County is composed of siderite and contains pyrite, barite, sphalerite and traces of calcite in its interior and in fractures. The siderite has 8I3C = + 0.65%o, Sr=289 ppm and 87Sr/86Sr=0.7110۪.0009 These results indie that the siderite was

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Siderite Wikipedia

Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase threedimensionally preserved fossils.

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Siderite Wikipedia

Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase threedimensionally preserved fossils.

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Geology 135 Sedimentation Diagenesis

Concretions often form early in diagenesis, shortly after compaction. Evidence for this is seen in the lack of compaction in layers and fossils preserved within the concretion relative to the layers outside of the concretion. Siderite and Pyrite. siderite (Fe2CO3) and pyrite (FeS2)

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Siderite concretions: indiors of early diagenesis in

The Gammon member of the Pierre shale of the northern Great Plains, USA, contains abundant siderite concretions. The relative depth and time of siderite precipitation can be inferred from the structure, mineralogy and isotopic composition of these concretions. Concretions that formed at shallow depths, early in the history of the sediment, contain a high percentage (7585%) of carbonate

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Rinded iron‐oxide concretions: hallmarks of altered

In all three deposits, rinded concretions formed when pre‐existing, siderite‐cemented concretions were oxidized within a sand matrix. Unlike fluvial examples, siderite in the Navajo Sandstone was autochthonous and of late diagenetic origin, having precipitated from carbon dioxide and methane‐enriched waters moving through folded and

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Siderite concretion Etsy

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Mazon Creek Formation Fossils Virtual Museum of Geology

Most fossils are found in concretions (siderite nodules) along the Mazon River area of the Illinois counties of Grundy, Will, Kankakee, Livingston and LaSalle, and are recovered from formation exposures along the river and nearby streams, roadcuts and within waste piles of abandoned and active coal mines.

Get price>