Minerals Siderite Research Articles

Are the iron carbonate minerals, ankerite and ferroan dolomite, like siderite, important in paleomagnetism?

Magnetic, Mössbauer effect, and thermal properties have been evaluated for specimens of the mineral ankerite and are contrasted with similar measurements reported for the mineral siderite to determine if ankerite (and ferroan dolomite), like siderite, may be important in paleomagnetism as a producer of secondary, spurious remanent moments as the result of oxidation in air. Our data indicate that ankerite and siderite both have comparable thermal stabilities and that ankerite does break down to form iron oxides at temperatures as low as 250°C during thermal demagnetization. We conclude from our data that any iron carbonate, siderite, ankerite, or ferroan dolomite, may readily oxidize in air to maghemite or hematite thus producing a spurious remanent moment (RM) that can dominate the magnetic properties of the specimen. Thermal demagnetization of ankerite or siderite at lower temperatures (below 250°C) does not appear to produce such a spurious RM. As might be expected, the quantity of secondary iron oxides produced by oxidation is limited by the iron content in the carbonate crystal lattice. Oxidized siderite produces significantly greater amounts of iron oxides than equivalent percentages of ankerite, which in turn produces more iron oxides than equal amounts of ferroan dolomite in a given sample.

Geochemistry of Precambrian carbonates: I. Archean hydrothermal systems

Carbonate rocks from the Superior and Slave Provinces of Canada, Kaapvaal Craton of South Africa and the Pilbara Block of Australia, considered of hydrothermal origin from field criteria, have been characterized mineralogically, isotopically (Sr, O, C) and chemically (major and trace elements). In agreement with previous studies, the bulk chemical composition suggests that the carbonate rocks originated by massive carbonatization, silicification and K (±Na) metasomatism of intermediate to ultramafic silicate precursors. The carbonate component itself defines two partially overlapping populations. The ferroan dolomite + breunnerite assemblage is confined mostly to shear zones, conduits and stockworks, while the calcite + ferroan dolomite (ankerite) ± siderite mineral assemblage represents a wider regional halo. This dichotomy may result from a multistory—not necessarily coeval—plumbing system of the volcanosedimentary piles, with the “regional halo” population being a product of shallow circulation cells, while the “conduit” assemblage probably formed from deeper focussed flows. Trace element chemistry of carbonates is consistent with their precipitation from relatively low salinity solutions (⩽2× sea water) and with derivation of solutes from the contemporaneous volcanosedimentary piles ( 87Sr 86Sr 0.7020 ± 0.0008) . The hydrothermal waters were derived either from metamorphic dewatering at the base of the piles, or from a magmatic source with δ 18O of about +6 ± 7%. SMOW. In contrast, carbon dioxide in the “regional” and the “conduit” assemblages had dissimilar principal sources. In the former it was derived from exogenic sources (decarbonation of marine carbonates and thermal decomposition and oxidation of organic matter), while in the latter the CO 2 was of “mantle” origin (δ 13C of +2 to −10 and −4 ± 2%. PDB, respectively).

Facies-Controlled Reservoir Properties in Ramp-Fan and Slope-Apron Deposits, Miocene Puente Formation, Los Angeles Basin: ABSTRACT

The Miocene Puente Formation in outcrops of the eastern Los Angeles basin is interpreted as a succession of slope-apron and ramp-fan deposits that accumulated in a prism-rise wedge. The principal depositional components of this dominantly base-of-slope and ramp system are ramp-fan channels and lobes, and slope-channel and slope-apron channel/interchannel deposits. Facies-specific textural, compositional, and diagenetic attributes observed in thin section assist in the classification of depositional facies. Specifically, occurrence of carbonate cement, clay mineralogy, and abundance of organic material vary as a function of component facies architecture of the depositional system. Slope and ramp-fan channel-fill sandstones are characterized by pervasive carbonate cements, including poikilotopic and fine-grained calcite, fine-grained and baroque dolomite, and minor siderite. Diagenetic clays predate carbonate cements, and dolomite predates coarser, void-filling calcite. Ramp-fan lobe and interchannel deposits are carbonate free but are rich in detrital clay and organic matter. Diagenetic clays include mixed-layer illite/smectite and kaolinite. Sediments deposited in slope-apron channel fill are virtually cement free except for small amounts of authigenic illite/smectite. Slope-apron interchannel deposits are characterized by high content of organic matter and clay-rich matrix. Potential reservoir characteristics, such as grain size, sorting, and abundance of depositional clay matrix, are related to the primary sedimentarymore » properties of depositional architectural components in the ramp-fan and slope-apron system. Additional diagenetic modifications, without consideration of compaction, were controlled by precipitation reactions associated with fluid flow along pathways related to the depositional architectural framework.« less

Siderite formation in anoxic deep-sea sediments: A synergetic bacteria controlled process with improtant implications in paleomagnetism

Research Article| November 01, 1988 Siderite formation in anoxic deep-sea sediments: A synergetic bacteria controlled process with improtant implications in paleomagnetism Brooks B. Ellwood; Brooks B. Ellwood 1Department of Geology, University of Texas, Arlington, Texas 76019 Search for other works by this author on: GSW Google Scholar Thomas H. Chrzanowski; Thomas H. Chrzanowski 2Department of Biology, University of Texas, Arlington, Texas 76019 Search for other works by this author on: GSW Google Scholar Frantisek Hrouda; Frantisek Hrouda 3Geofyzika, národní podnik, Brno, Czechoslovakia Search for other works by this author on: GSW Google Scholar Gary J. Long; Gary J. Long 4Department of Chemistry, University of Missouri, Rolla, Missouri 65401 Search for other works by this author on: GSW Google Scholar Margaret L. Buhl Margaret L. Buhl 4Department of Chemistry, University of Missouri, Rolla, Missouri 65401 Search for other works by this author on: GSW Google Scholar Geology (1988) 16 (11): 980–982. https://doi.org/10.1130/0091-7613(1988)016<0980:SFIADS>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Brooks B. Ellwood, Thomas H. Chrzanowski, Frantisek Hrouda, Gary J. Long, Margaret L. Buhl; Siderite formation in anoxic deep-sea sediments: A synergetic bacteria controlled process with improtant implications in paleomagnetism. Geology 1988;; 16 (11): 980–982. doi: https://doi.org/10.1130/0091-7613(1988)016<0980:SFIADS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Recent work on magnetic properties of limestones has demonstrated that the mineral siderite can be very important in paleomagnetism, for two reasons. First, oxidation of siderite produces secondary (daughter) magnetic minerals (magnetite, maghemite, and hematite), either before, during, or after sampling. These daughter products can completely change the magnetic properties of limestone samples and if unrecognized may be one of the primary reasons why many paleomagnetic studies of limestones, especially Paleozoic limestones, are unsuccessful. Second, siderite in weakly magnetized rocks may indicate the potential for successful paleomagnetic results. Because the presence of siderite indicates that the primary magnetic carriers are still intact, appropriate demagnetization methods should yield successful results. We conclude that microenvironmental conditions in anoxic marine sediments may permit the formation of siderite from iron (II) produced during bacterial dissimilatory iron reduction. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Laser probe 40Ar/39Ar and conventional K/Ar dating of illites associated with the McClean unconformity-related uranium deposits, north Saskatchewan, Canada

The McClean group of uranium deposits consists of elongate pods of high-grade uranium mineralization (width = ~ 15–40 m) tightly confined to within ±40 m of the basal unconformity. Uraninite–coffinite–sulphide/arsenide–chlorite–siderite mineralization at McClean is surrounded by a muscovite/illite ± haematite hydrothermal alteration halo,which can contain coffinite–pararammelsbergite (NiAs2) – muscovite/illite nodules. Ten laser probe 40Ar/39Ar dates, two of which are step-heat runs showing good plateaus, and 10 conventional K – Ar dates for this material show a distribution with asharp beginning at ~ 1320 Ma, a marked peak in the 1250–1200 Ma class interval, and a tail to dates as young as 1002 ± 33 (1σ) Ma. These determinations are in complete agreement with direct (U–Pb and Sm–Nd) dates on uraninite at the Midwest (e.g., 1328 ± 9 and 1110 ± 28 Ma), Key Lake (e.g., 1350 ± 4 and 1281 ± 6 Ma), and Collins Bay B deposits(e.g., 1281 ± 80 Ma). Since estimated depositional ages for the Athabasca sedimentary sequence are in the 1470 ± 15 to1428 ± 15 Ma range, uranium mineralization and associated hydrothermal alteration started ~ 100–150 Ma after Athabasca sedimentation, a result consistent with fluid-inclusion data, which indicate that mineralization took place at ~ 160–220 °C beneath ~ 3000 m of cover at a relatively advanced stage in the evolution of the basin. It is suggested that the similar initiation dates for uranium mineralization might reflect a widespread faulting event that affected the eastern part of the basin. A muscovite/illite closure temperature calculated from a measured argon diffusion activation energy of 36 ± 4 kcal/mol(1 kcal = 4.1868 kJ) indicates that the base of the Athabasca Basin in the McClean area has not been disturbed by temperatures greater than ~ 140 °C for 1.1–1.0 Ga. It is suggested that mineralization ceased when fracture permeability had been sealed by crystallization of secondary minerals. The duration of mineralization may have been ~ 150 Ma, a relatively long time interval not unreasonable for the base of a sedimentary basin.Secondary illites interstitial to quartz grains from the HLM1 stratigraphic borehole give 40Ar/39Ar ages of 1459 ± 4, 1341 ± 4, and 1113 ± 11 Ma, indicating that formation of diagenetic sheet silicates predated uranium mineralization. Recrystallization or formation of sheet silicates in relict sedimentary layers and in subunconformity altered basement referred to as "regolith" started at approximately the same time, since dates of 1484 ± 55 Ma (sedimentary layer), 1482 ± 49 Ma (regolith), and 1453 ± 49 Ma (regolith) have been obtained. Resetting of interstitial, sedimentary layer, and regolith sheet-silicate dates continued to ages of, for example, 1113 ± 11 Ma (interstitial) and 1038 ± 55 Ma (sedimentary layer), which exactly coincide with the youngest ages obtained for the alteration halo associated with mineralization.The youngest date obtained is a 40Ar/39Ar plateau age of 673 ± 3 Ma. The sample (2045-517) was obtained from within 2 mm of a concentrated pitchblende nodule and may have been disturbed in some way by its proximity to uranium.

Anomalous magnetic properties in rocks containing the mineral siderite: Paleomagnetic implications

Sampling and magnetic measurement of a 1‐m bed in a new road cut of the Upper Cretaceous Austin Chalk (northeastern Texas) has yielded anomalous magnetic results. Initial measurement of the anisotropy of magnetic susceptibility (AMS) indicated unusually high anisotropies and low bulk susceptibilities characteristic of a magnetocrystalline anisotropy which might be expected for siderite (FeCO3). Natural remanent moments (NRM) for these samples were low (&lt;1 × 10−4 A m2), and directions were typical for samples which had acquired a normal geomagnetic field overprint at the site. Periodic remeasurement of the NRM yielded an increase in moment for some samples and periodic reversals of RM in a direction parallel or antiparallel to the ambient field in the laboratory. Isothermal remanent moments of these samples saturates at low induction values (∼200 mT). AMS remeasurement over a period of weeks to months revealed a general decrease in the anisotropy magnitudes, an increase in susceptibility, and a change in principal axis orientations. These data were compared with heating (oxidation) experiments on Austin Chalk, siderite ore, and clastic sediments with siderite cements. All of these results are consistent with the X‐ray diffraction and Mössbauer data, which indicate the presence of siderite in the Austin Chalk samples. The Mössbauer spectra of the samples obtained at room temperature and 78°K indicate the presence of approximately 80% pyrite, 10% siderite, and 10% of a clay component (possibly chlorite) when only the iron‐bearing mineral components are considered. After sampling, exposure to the air, and subsequent oxidation in the laboratory, the siderite in Austin Chalk samples appears to have altered to γFe2O3 (maghemite) or Fe3O4 (magnetite), increasing the magnetic moment and changing the NRM and AMS directions in the samples. The continuing changes appear to reflect a conversion from the less stable γFe2O3 to αFe2O3 (hematite) or oxidation of Fe3O4 to αFe2O3. We infer from our study that oxidation of siderite‐bearing limestone (e.g., during the formation of unconformities or due to low‐magnitude tectonic events) may produce a very stable secondary magnetic moment in the rock. Such changes may be very important when interpreting paleomagnetic data from limestones.

Ba'id al Jimalah tungsten prospect, Najd region, Kingdom of Saudi Arabia

The Ba'id al Jimalah tungsten prospect is located in the NE of the Arabian Shield, at 25°09′N, 42°41′E. Mineralization is associated with a late-Proterozoic, porphyritic microgranite emplaced in folded, fine-grained clastic rocks of the Murdama group, within an aureole of biotite-rich hornfels. The microgranite forms a 30 m-thick sill and numerous smaller sills and dikes cropping out along two low, sub-parallel ridges and several small hills in an area 700 m square. The form of the intrusion at depth is uncertain. It is slightly to intensely sericitized, in places greisenized, and is enriched in Li, F and Rb. Wolframite occurs with minor cassiterite, scheelite and sulfides in quartz veins cutting both microgranite and hornfelsed wall-rock. The veins have a dominant trend of 110–115°, and are thicker and more numerous in the microgranite. Gangue minerals include plagioclase and potassium feldspar, muscovite, sericite, fluorite and minor siderite. A major Najd fault trending 130–135° probably controlled magma emplacement and subsequent hydrothermal and pneumatolytic activity. A percussion drilling program, restricted to the outcrop of the sill on the north ridge, has outlined 800,000 tonnes grading 0.10% WO 3 and 0.01% Sn.

Thermal analysis studies of the dolomite, ferroan dolomite, ankerite series. Part 1. Iron content recognition and determination by variable atmosphere DTA

Under static air furnace atmosphere conditions, high Fe ferroan dolomites and ankerites give characteristic three-endothermic-peaked DTA curves. On dilution, peak resolution deteriorates and eventually the minerals give only a single broad peak of greatly decreased diagnostic value. In contrast, determinations in flowing carbon dioxide result in increased peak separation, definition and height, while individual peaks remain recognisable (without coalescence) down to the limits of detection, which are greatly improved. This complete separation of the three peaks of ankerite permits a true evaluation of the now unmodified middle endothermic peak which decreases with falling iron content. Based on this peak, the detection limit of iron, expressed as wt.% FeCO 3 component in the dolomite structure, is of the order of 1%. The presence of Fe in the mineral siderite may be clearly distinguished from the Fe present as ferroan dolomite/ankerite.

Application of thermomagnetometry to the study of siderite

Thermogravimetry in the presence of an external magnetic field is used to detect the presence or absence of magnetic intermediates and products during the thermal decomposition of several siderite minerals (FeCO 3). The Curie temperature of the product phase indicates that several of the major impurities are incorporated into the spinel product in nitrogen. In oxygen no spinel intermediate phases are detected.

Influence of Diagenetic Reactions on Nonmarine Upper Cretaceous Rocks of Southman Canyon Gas Field, Uinta Basin, Utah: ABSTRACT

End_Page 832------------------------------Natural gas is produced from sandstone in the Upper Cretaceous Neslen, Farrer, and Tuscher Formations in the southeastern Uinta basin. Examination of these sandstone units along the eastern Book Cliffs indicates that most of the reservoir units are part of alluvial channels. Sandstone beds in the Neslen represent relatively small and isolated meandering channels in swampy coastal plains. Sandstone beds in the Farrer were deposited by somewhat larger and more numerous meandering streams depositionally upslope from the Neslen setting. The Tuscher Formation represents the most landward facies and was deposited principally by meandering, laterally migrating, large streams with local braided courses. Core samples from the Southman Canyon gas field studied with the scanning electron microscope (SEM) indicate that extensive diagenetic modifications of the reservoir rocks have occurred and have strongly influenced reservoir characteristics. Authigenic overgrowths on detrital quartz are common, but secondary silica is not a significant cementing agent. Feldspars are not abundant and are commonly altered to illitic clay. Carbonate minerals--dolomite, ankerite, calcite, and minor siderite--account for up to 20% of the rock. They are generally interstitial and have replaced some detrital quartz and rock fragments. Chert and other rock fragments account for more than 20% of the volume of many sandstones. Some rock fragments are extensively altered by mechanical deformation, dissolution, and clay-mineral formation. Dissolution and leaching, primarily of rock fragments, have improved the reservoir storage capacity of the sandstone units by producing a significant amount of intergranular and intragranular secondary porosity. The dissolution and leaching appear to have exerted a greater influence on reservoir characteristics than did mechanical deformation and growth of authigenic minerals. Most porosity in the units is of secondary origin. End_of_Article - Last_Page 833------------

PENETRATION OF MOLLUSCAN AND NON-MOLLUSCAN MINERALS BY THE BORING GASTROPODUROSALPINX CINEREA

1. Results of an experimental study of the capacity of Urosalpinx cinerea follyensis Baker to penetrate 15 kinds of molluscan and abiogenic minerals are reported. Minerals, cut into small wafers, and radular teeth were exposed to penetration by normally boring snails in valve models. Depth of incomplete boreholes was measured with a compound microscope. Extent of dissolution was examined with a scanning electron microscope. All biogenically formed calcareous minerals, except radulae of U. cinerea, and some abiogenic minerals, were penetrated. Rate of penetration of wafers decreased in the following order: calcite and aragonite (shell of Crassostrea virginica, Spisula solidissima, Anomia simplex), strontianite, bone and tooth hydroxyapatite, anhydrite, witherite, and magnesite. Abiogenic minerals siderite, smithsonite, alunite, fluorite, and quartz were not penetrated. Of the 15 tests performed on biogenically formed calcareous minerals, only two snails (or 13%) left the sample on the model before the experiment was terminated; of the 25 tests on abiogenically formed minerals, 20 snails (80%) crawled off the sample before the end of the tests. Experiments demonstrated that Ca, Sr, Ba, and Mg, as carbonates, and Ca both as the phosphate and sulfate, were attacked by the secretion. Fe and Zn, as the carbonates, Ca as the fluoride, Si as the oxide, and K and Al as the sulfate were unaffected.2. Degree of penetration of beef bone was intermediate between that of shell and human teeth. Dentine was penetrated more deeply than enamel. The core of enamel prisms was dissolved more deeply than the outer region by the secretion. Radular teeth of U. cinerea were unaffected by the secretion during exposures ranging from 0.5 to 2.5 hr.3. The capacity of U. cinerea to penetrate a wide range of types of minerals explains, in part, the large number of different species upon which it can prey.

Conversion electron Mössbauer spectroscopy and the study of surface properties and reactions

Unlike transmission Mössbauer spectroscopy which, in order to be of widespread utility in surface science, requires high-area solids, conversion electron Mössbauer spectroscopy (CEMS) is applicable to a wide range of low-area materials containing iron (or tin). The necessary conditions required for optimal detection of internally converted electrons (which are emitted from distances of ca. 300 nm below the exterior surface) are outlined, and the surface sensitivity of the technique demonstrated by reference to, inter alia, the determination of the rate coefficient of the parabolic oxidation rate of iron at 500°C and the detection of goethite as a weathering product of the mineral siderite. The application of this technique to other problems in materials science is discussed, and factors governing the characteristics of depth-profiling of specimens of oxidized or corroded iron (or iron-containing material) are discussed by reference to an energy analyzing spectrometer, the essential features of which are described. The merit of acquiring depth sensitive CEM spectra is illustrated by reference to the detection of a doublet which is associated with the iron/oxide interface.

Physical and Chemical Properties of Mississippi River Alluvial Valley and Delta Clays: ABSTRACT

End_Page 527------------------------------Areal distributions of clay suites of the central Gulf of Mexico area have been studied mainly by X-ray diffraction, using peak-height ratios as an index to the nature of clays. This approach alone yields little information regarding effects of depositional environments. The present study couples geochemical techniques with analysis of other environmental indicators and emphasizes effects of organic and inorganic processes associated with deposition and early diagenesis. Undisturbed samples from both active environments and deep borings were utilized. Samples from freshwater alluvial valley and upper deltaic-plain environments were compared with others from brackish and saline environments of the lower delta. Laboratory techniques included X-ray radiography, X-ray radiography, X-ray d ffraction, X-ray spectrography, atomic absorption spectrophotometry, and microsteam distillation. Clays deposited in channel and natural levee environments show little modification from the basic transported suite carried by the Mississippi (predominantly montmorillonite with appreciable amounts of illite and kaolinite). Minor differences attributed to seasonal fluctuations in flow regimes of major tributaries are detectable in suspended load and bottom samples. Percent organic C and cation-exchange capacities tend to decrease toward the river mouth. In the lower delta, properties of delta-front and prodelta clays show distinct gradients, reflecting velocity decrease, water-depth increase, salinity increase, and mixing with shelf clays. Clays become more kaolinitic, less calcium saturated, and more sodium saturated seaward from distributary mouths. In these environments high soluble salt content is associated with a distinct texture and lamination produced by salt flocculation. Integrated intensity ratio logs of montmorillonite-plus-illite/kaolinite from deep lower-delta borings not only exhibit trends related to delta progradation, but also show clay-mineral zonation resulting from shifting delta lobes. This zonation has been useful particularly in solving stratigraphic problems associated with diapiric mud-lump structures. Clays are introduced into upper deltaic plain fresh-water basins largely by overbank flow from the main distributaries. Paludal and lacustrine environments are characterized by low rate of detrital introduction, high rates of organic and inorganic chemical deposition, high pH (>8.0), and warm, stagnant water. Despite the fact that secondary minerals (siderite, calcium carbonate, pyrite, vivianite, etc.) in the form of nodules and cementing agents are abundant and form rapidly, the basic nature of the clay remains unaltered even after burial for several thousand years. End_of_Article - Last_Page 528------------

Magnetic Studies on Siderite (FeCO3)

Principal magnetic susceptibilities and crystal anisotropy of six samples of mineral siderite have been measured from 100°K to 500°K. Each sample was analyzed for its chemical composition. It has been shown that the crystalline electric field acting on ferrous ion in siderite is of trigonal symmetry. A broad maxima in susceptibility versus temperature around 300°K has been observed. Variation of observed magnetic moment normal to the trigonal axis is complicated.

Cobalt mineralization in the Blackbird District, Lemhi County, Idaho

The cobalt mineralization in the Blackbird district of Lemhi County, Idaho, probably the most extensive mineralization of its kind in the United States, is confined to irregular and discontinuous veins and lodes along zones of fractured and schistose quartzite belonging to the Belt series (pre-Cambrian). These lodes are represented by (1) zones of cobaltite-impregnated tourmalinized quartzite (cobalt-tourmaline lodes); (2) zones of cobaltite-impregnated biotitized quartzite (cobalt-biotite lodes); (3) bodies of cobaltite-containing quartz in zones of cobaltite-impregnated biotitized quartzite (cobalt-quartz lodes); and (4) stringers and lenses of quartz and such ore minerals as cobaltite, native silver, chalcopyrite, gold, and electrum in zones of cobaltite-impregnated biotitized quartzite (gold-copper-cobalt lodes).These lodes are the products of three stages of mineralization: (1) an early cobalt stage during which biotite, tourmaline, and cobaltite were formed, (2) a copper-cobalt stage during which biotite, quartz, cobaltite, arsenopyrite, pyrite, pyrrhotite, native silver, chalcopyrite, siderite and other minerals were deposited, and (3) a gold-electrum stage during which scant amounts of these minerals and quartz were deposited. The differences that exist among the lodes depend largely on the variations in the amounts and kinds of minerals added during each stage of mineralization. All lodes show marked effects of the first stage of mineralization; the cobalt-quartz and the gold-copper-cobalt, also the effects of the second stage; and the gold-copper-cobalt lodes, mild effects of the third.The mineralizing solutions apparently had their source in early Tertiary magma which also provided the substance for accompanying bodies of gabbro and lamprophyre. Lode schistosity, which developed concomitantly with the mineralization, indicates deposition along zones of deepseated shearing under intense stress conditions. Mineral associations suggest relatively high temperatures, particularly when cobaltite was deposited. The early-stage solutions apparently carried the cobalt direct from its magmatic source, but the cobalt contained in the second-stage solutions was probably obtained by solution of the earlier-deposited cobaltite.