scholarly journals Mg-Phengite in Carbonate Rock Syngenetically Formed from Hydrothermal Fluid: Micro-Textural Evidence and Mineral Chemistry

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 668
Author(s):  
Chaewon Park ◽  
Namsoo Kim ◽  
Sung-Ja Choi ◽  
Yungoo Song
Keyword(s):  
Hydrothermal Fluid ◽  
Fine Sand ◽  
Structural Formula ◽  
Mineral Chemistry ◽  
Crystalline Dolomite ◽  
Polycrystalline Aggregates ◽  
Form Type ◽  
Clastic Sedimentary ◽  
End Members ◽  
Type 3

Phengite series is a dioctahedral solid solution between two end-members of muscovite [K1[Al2]VI[Al1,Si3]IVO10(OH)2] and celadonite [K1[(Fe3+,Al)1,(Mg,Fe2+)1]VI[Si4]IVO10(OH)2], which have a hetero-valent substitution of AlVIAlIV ↔ (Mg, Fe)VISiIV. In this study, we report a hydrothermal-originated authigenic Mg-phengite-series mineral, which occurred as polycrystalline aggregates (Type 1), pore-fillings (Type 2) and well-crystallized lath form (Type 3) from the Haengmae Formation, a dolomite–pebble-bearing fine sand-sized dolostone, in South Korea. Based on micro-textural observation, three types of Mg-phengite are associated with crystalline dolomite, and are followed by calcite precipitation as pore-filling, indicating that these should be formed by the influx of a Mg-rich hydrothermal fluid after the deposition of some clastic sediments and before calcite-filling. The structural formula based on O10(OH)2 shows that the number of Mg atoms per formula unit (apfu) of Mg-phengite ranges from 0.00 to 0.70 with no Fe, which is relatively high, compared with the previously reported metamorphic phengites. In REEs mineral chemistry, the Mg-phengites are characterized by the enrichment of REEs and by the particular enrichment of LREEs in the polycrystalline aggregates of Mg-phengite. It strongly suggests that the Mg-phengite should be formed by the infiltration of the highly evolved Mg- and REEs-enriched hydrothermal fluid into the clastic sedimentary rock (Haengmae Formation) as a strata-bound form, syngenetically or during early diagenesis.

Oxygen, hydrogen, and strontium isotope constraints on the origin of granites

1988 ◽  
Vol 79 (2-3) ◽  
pp. 317-338 ◽  
Author(s):  
Hugh P. Taylor
Keyword(s):  
Large Scale ◽  
Wide Spectrum ◽  
Volcanic Field ◽  
Parent Material ◽  
Rock Interaction ◽  
Metasedimentary Rocks ◽  
Clear Cut ◽  
End Members ◽  
Type 3

ABSTRACTOxygen isotope data are very useful in determining the source rocks of granitic magmas, particularly when used in combination with Sr, Pb, and Nd isotope studies. For example, unusually high δ18O values in magmas (δ18O> +8) require the involvement of some precursor parent material that at some time in the past resided on or near the Earth's surface, either as sedimentary rocks or as weathered or hydrothermally altered rocks. The isotopic systematics which are preserved in the Mesozoic and Cenozoic batholiths of western North America can be explained by grand-scale mixing of three broadly defined end-members: (1) oceanic island-arc magmas derived from a “depleted” (MORB-type?) source in the upper mantle (δ18O c. +6 and 87Sr/86Sr c. 0·703); (2) a high-18O (c. +13 to +17) source with a very uniform 87Sr/86Sr (c. 0·708 to 0·712), derived mainly from eugeosynclinal volcanogenic sediments and (or) hydrothermally altered basalts; and (3) a much more heterogeneous source (87Sr/86Sr c. 0·706 to 0·750, or higher) with a high δ18O (c. +9 to +15) where derived from supracrustal metasedimentary rocks and a much lower δ18O (c. +7 to +9) where derived from the lower continental crust of the craton. These end-members were successively dominant from W to E, respectively, within three elongate N–S geographic zones that can be mapped from Mexico all the way N to Idaho.18O/16O studies (together with D/H analyses) can, however, play a more important and certainly a unique role in determining the origins of the aqueous fluids involved in the formation of granitic and rhyolitic magmas. Fluid-rock interaction effects are most clear-cut when low-18O, low-D meteoric waters are involved in the isotopic exchange and melting processes, but the effects of other waters such as seawater (with a relatively high δD c. 0) can also be recognised. Because of these hydrothermal processes, rocks that ultimately undergo partial melting may exhibit isotopic signatures considerably different from those that they started with. We discuss three broad classes of potential source materials of such “hydrothermal-anatectic” granitic magmas, based mainly on water/rock (w/r), temperature (T), and the length of time (t) that fluid-rock interaction proceeds: (Type 1) epizonal systems with a wide variation in whole-rock δ18O and extreme 18O/16O disequilibrium among coexisting minerals (e.g. quartz and feldspar); (Type 2) deeper-seated and (or) longer-lived systems, also with a wide spectrum of whole-rock δ18O, but with equilibrated 18O/16O ratios among coexisting minerals; (Type 3) thoroughly homogenised and equilibrated systems with relatively uniform δ18O in all lithologies. Low-18O magmas formed by melting of rocks altered in a Type 2 or a Type 3 meteoric-hydrothermal system are the only kinds of “hydrothermal-anatectic” granitic magmas that are readily recognisable in the geological record. Analogous effects produced by other kinds of aqueous fluids may, however, be quite common, particularly in areas of extensional tectonics and large-scale rifting. The greatly enhanced permeabilities in such fractured terranes make possible the deep convective circulation of ground waters and sedimentary pore fluids. The nature and origin of low-18O magmas in the Yellowstone volcanic field and the Seychelles Islands are briefly reviewed in light of these concepts, as is the development of high-D, peraluminous magmas in the Hercynian of the Pyrenees.

scholarly journals ORE MINERALOGY AND MINERAL CHEMISTRY OF PYRITE, GALENA, AND SPHALERITE AT SORIPESA PROSPECT AREA, SUMBAWA ISLAND, INDONESIA

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Win Kant ◽  
I Wayan Warmada ◽  
Arifudin Idrus ◽  
Lucas Donny Setijadji ◽  
Koichiro Watanabe
Keyword(s):  
Low Temperature ◽  
Hydrothermal Fluid ◽  
Mineral Chemistry ◽  
Careful Study ◽  
Average Content ◽  
Thin Sections ◽  
Content Ratio ◽  
Fe Content ◽  
Ore Minerals ◽  
Ore Mineralogy

The Soripesa prospect area is located at Maria village, Wawo district, Bima region in the East Sumbawa Island, Indonesia. Lithology is dominantly composed of a lithic-crystal tuff of andesitic and dacitic composition and bedded limestone. The polymetallic epithermal quartz veins are hosted by andesitic volcaniclastic rocks. Within these veins, multiphases, colloform-crustiform, bedding to massive textures with pyrite, sphalerite, galena, chalcopyrite, chalcocite, azurite, and malachite are observed. Selected samples were analyzed by using ore microscopy and SEM-EDX. Ore minerals show replacement, ex-solution, colloform, and zonal textures. The paragenesis diagram was made from a careful study of polished sections and thin sections. Textures of ore minerals such as banded, exsolution, replacement, and zone, have been interpreted to correspond to the order of deposition. In pyrite, the average content of Co (0.45 wt.%) is higher than Ni content (0.14 wt.%) and it means that their origin may be hydrothermal origin. Average content ratio, Co:Ni is 2.81. Galena shows a low Ag content of 0.07 %in average. But they show a high Au content of 1.48 %in average. Sphalerite shows a low Fe content of 1.04 %in average and occasionally chalcopyrite inclusion/disease also occurred. Ga and Ge contents are also high in sphalerite. Co>Ni in pyrite, low content of Ag in Galena, low content of Fe and mole % FeS in sphalerite, high content of Ga and Ge, and log (Ga/Ge) in sphalerite, show that pyrite, galena, and sphalerite from Soripesa prospect area were formed under low temperature condition of hydrothermal fluid. Keywords: Ore textures, paragenesis, deposition, hydrothermal fluid, low temperature

A New Look at the Galim (a) and Galim (b) Meteorites

1988 ◽  
Vol 52 (367) ◽  
pp. 519-525 ◽  
Author(s):  
Mireille Christophe Michel-Lévy ◽  
Michèle Bourot-Denise
Keyword(s):  
Mineral Chemistry ◽  
The Other ◽  
Reducing Conditions ◽  
Enstatite Chondrite ◽  
Type 3 ◽  
New Look

AbstractSmall stones were recovered from a meteorite shower observed in Cameroon on November 13, 1952. The majority are LL6 specimens, Galim (a), but one is a chondrule-rich enstatite chondrite, Galim (b). Petrology and mineral chemistry were determined on polished sections of both types. Galim (a) has undergone multiple brecciation. During the first, chromite apparently recrystallized in healed fractures under more reducing conditions than those which prevailed when the silicates recrystallized. Galim (b) shows some features of petrologic type 3 but differs considerably from the other unequilibrated E chondrites. It is suggested that Galim (a) and Galim (b) belong to the same meteorite shower.

Geochemistry and tectonic discrimination of Late Proterozoic arc-related volcaniclastic turbidite sequences, Antigonish Highlands, Nova Scotia

1993 ◽  
Vol 30 (12) ◽  
pp. 2273-2282 ◽  
Author(s):  
J. Brendan Murphy ◽  
Deborah L. MacDonald
Keyword(s):  
Nova Scotia ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Widespread Application ◽  
Isotopic Signatures ◽  
Late Proterozoic ◽  
Felsic Volcanic ◽  
Clastic Sedimentary ◽  
End Members

The Late Proterozoic (ca. 618–610 Ma) Georgeville Group of northern mainland Nova Scotia lies within the Avalon Composite Terrane and consists of subgreenschist- to greenschist-facies mafic and felsic volcanic rocks overlain by volcaniclastic turbidites that were deposited in an ensialic basin within a rifted volcanic arc. Geochronological data indicate that the volcanic and sedimentary rocks are coeval. The geochemical and isotopic signatures of the sedimentary rocks are attributed to erosion of the coeval Avalonian volcanic rocks that flank the basin and are consistent with synorogenic deposition. There is no evidence of significant chemical contribution from Avalonian basement.Knowledge of the tectonic setting facilitates the testing of published geochemical discriminant diagrams for clastic sedimentary rocks. Discrimination diagrams using ratios such as K2O/Na2O and Al2O3/(CaO + Na2O) give inconclusive results, probably due to elemental mobility during secondary processes. Plots involving MgO, TiO2, and Fe2O3 detect the chemical contribution of mafic detritus, give much tighter clusters of data, and plot between Aleutian- and Cascade-type arc-derived sediments, suggesting a moderate thickness of continental crust beneath the arc.The arc-related signature of the Georgeville sedimentary rocks is clearly recognizable on ternary plots involving inter-element ratios of high field strength elements (e.g., Ti–Y–Zr, Nb–Y–Zr, and Hf–Ta–Th) in which the samples plot as mixing trends between mafic and felsic end members. Diagrams of this type may have widespread application to tectonic discrimination of sedimentary rocks because in most suites these ratios are relatively insensitive to sedimentary and metamorphic processes.

scholarly journals Multistage origin of dunite in the Purang ophiolite, southern Tibet, documented by composition, exsolution and Li isotope characteristics of constituent minerals

2020 ◽  
Vol 32 (1) ◽  
pp. 187-207
Author(s):  
Fahui Xiong ◽  
Jingsui Yang ◽  
Hans-Peter Schertl ◽  
Zhao Liu ◽  
Xiangzhen Xu
Keyword(s):  
Partial Melting ◽  
Mantle Wedge ◽  
Mantle Peridotite ◽  
Southern Tibet ◽  
Olivine Structure ◽  
Form Type ◽  
Type 3 ◽  
Podiform Chromitite

Abstract. The Purang ophiolite, which crops out over an area of about 650 km2 in the western Yarlung–Zangbo suture zone, consists chiefly of mantle peridotite, pyroxenite and gabbro. The mantle peridotite is comprised mainly harzburgite and minor dunite. Locally, the latter contains small pods of chromitite. Pyroxenite and gabbro occur as veins of variable size within the peridotite; most of them strike northwest, parallel to the main structure of the ophiolite. Three types of dunite occur in the Purang ophiolite: dunite that envelopes podiform chromitite (1) and lenses of dunite with either Cr-rich spinel (2) or Cr-poor spinel (3) in a harzburgite host. The constituent minerals of dunite envelopes around podiform chromitite are similar in composition to those of transition-zone dunite (Fo91.01−91.87 in olivine; Cr/(Cr+Al) (Cr#) =41.5–47.0 and Mg/(Mg+Fe2+) (Mg#) =58.9–63.0 in Cr-spinel). Forsterite contents in olivine decrease from type 2 lenses with Cr-rich spinel (91.9–93.0) to type 1 dunite enveloping chromitite (91.7–93.7) to type 3 lenses with Cr-poor spinel (95.3–96.0). Similarly, Cr# in spinel decreases from type 2 (66.9–67.9) to type 1 (41.5–47.0) to type 3 (19.8–20.6). In addition, Al2O3 in clinopyroxene is highest in type 2 (3.48–5.24 wt %) and decreases to type 1 (1.56–3.29 wt %) and type 3 (0.78–0.86 wt %). Olivine in type 1 dunite enveloping podiform chromitite has Li concentrations and δ7Li values of 1.48–1.71 ppm and 6.19 ‰–7.98 ‰, respectively. Type 2 dunite lenses with Cr-rich spinel contain olivine with Li =0.98–1.64 ppm and δ7Li =6.77 ‰–10.99 ‰. The type 3 dunite lenses with Cr-poor spinel show the highest values of Li =0.94–1.40 ppm and δ7Li =10.25 ‰–14.20 ‰. Exsolution lamellae of clinopyroxene and magnetite occur as oriented intergrowths in olivine of type 3 dunite lenses with Cr-poor spinel. We suggest that the Purang ophiolite developed during two main stages of formation. In the first stage, abyssal peridotites formed in a mid-ocean-ridge environment. During the second stage, hydrous high-Mg boninitic melts were produced by high degrees of partial melting in a supra-subduction zone mantle wedge, which reacted with peridotite to form type 2 dunite pods with high-Cr# spinel. At lower degrees of partial melting in the same mantle wedge, Al-rich melts were produced, which reacted with peridotite to form type 3 dunite pods that contain low-Cr# spinel. These Al-rich melts were also relatively rich in Ti4+, Ca2+ and Fe3+, which were incorporated into the olivine structure by appropriate substitutions. During cooling, these elements exsolved as lamellae of magnetite and clinopyroxene.

scholarly journals Gaucher's Disease- A case report

2014 ◽  
Vol 3 (2) ◽  
pp. 45-48
Author(s):  
ASM Ruhul Quddush ◽  
Md Kamruzzaman ◽  
Md Badruzzaman ◽  
Mirja Hamidul Haque ◽  
Nazma Parvin Ansari ◽  
...  
Keyword(s):  
Gaucher Disease ◽  
Abdominal Distension ◽  
Disease Type ◽  
X Ray ◽  
Enzyme Replacement ◽  
Gaucher Disease Type 1 ◽  
Form Type ◽  
Type 3

A 3 years old immunized girl of consanguineous parents presented abdominal distension with hepatosplenomegaly. She was moderately anemic, moderately wasted and stunted. Neurological examination was normal. Musculoskeletal system examination revealed no abnormality. Diagnosis was supported by typical bone involvement in X-ray film (thin cortex in limb bone) and gaucher cell in the bone marrow and also in the splenic aspiration. There are three subtypes Type1: Non neuropathic form, Type 2: Acute neuropathic form, Type 3: Chronic neuropathic form. However some cases do not fit precisely into one of these categories. All forms of Gaucher disease are autosomal recessively inherited. So, this patient more or less correlates with Gaucher disease type 1. Treatment option for type 1 and 3 include medicine and enzyme replacement therapy, which is usually very effective. CBMJ 2014 July: Vol. 03 No. 02 P: 45-48

Mineral chemistry and genetic relations among H-group chondrites

1981 ◽  
Vol 374 (1757) ◽  
pp. 159-178 ◽  
Keyword(s):  
Mineral Chemistry ◽  
Solidification Structure ◽  
Liquid Fractionation ◽  
Type 3 ◽  
Lines Of Evidence

The chondrites Bremervorde and Tieschitz (both H3), Beaver Creek, Menow, Monroe and Quenggouk (all H4), Allegan and Ambapur Nagla (both H5), and Butsura and Kernouve (both H6) were studied. Ca-poor pyroxenes almost invariably show enrichment in Mg relative to coexisting olivines; this was established in Tieschitz chondrules and in Bremervorde by crystal-liquid equilibria. In each chondrite, Ca-poor pyroxenes typically have less than 2 mol % wollastonite. In petrologic types 3 and 4, chondrule mesostases frequently show enrichment in normative diopside, which occurs as a resolvable modal phase in the type 6 chondrites. Partition of Ca between the two pyroxenes was initiated by crystal-liquid fractionation. Various chemical inhomogeneities may be traced from type 3 meteorites to those of type 6. Polycrystalline taenite occurs in Tieschitz, Bremervörde, Menow, Quenggouk and Butsura; it is rarely present in Kernouve. This textural form of taenite is interpreted as a relict solidification structure produced from a quenched liquid, which must have cooled rapidly to below about 700 °C. We argue that equilibration of the H-group chondrites took place during cooling, mainly from about 700 °C, which is compatible with several lines of evidence. If metamorphism is defined as change induced by an increase in temperature, then in the H-group chondrites studied we recognize it only in transient reheating probably produced by shock.

scholarly journals Use of TEM-EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam

2019 ◽  
Vol 52 (1) ◽  
pp. 133-147 ◽  
Author(s):  
Thao Hoang-Minh ◽  
Jörn Kasbohm ◽  
Lan Nguyen-Thanh ◽  
Pham Thi Nga ◽  
Le Thi Lai ◽  
...  
Keyword(s):  
Structural Formula ◽  
X Ray Diffraction ◽  
Sedimentary Process ◽  
X Ray ◽  
Weathering Processes ◽  
Transmission Electron ◽  
Analytical Proof ◽  
Structural Formulae ◽  
Diffraction Patterns ◽  
End Members

Transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) was applied to characterize mineralogical signals of weathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X-ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X-ray diffraction, X-ray fluorescence and Fourier-transform infrared spectroscopy (FT-IR) methods were also applied to verify the TEM-EDX results. An Excel-based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100–300 TEM-EDX analyses as a representative set of individual particles for each sample. The Excel-based routine involves end members of different clay-mineral groups and interstratifications with two or three members (e.g. illite–smectite interstratifications – IS-ml; dioctahedral vermiculite–smectite interstratifications – diVS-ml; and kaolinite–montmorillonite–dioctahedral vermiculite interstratifications – KSV-ml). The routine is now freely available. According to the identification procedure, the <2 µm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K- and charge-deficient illite–smectite interstratifications (or diVS-ml): montmorillonite-rich randomly ordered (R0) type and illite-rich regularly ordered (R1) type. Additionally, Fe-poor KSV-ml was identified. Industrial Na activation of the Di Linh bentonite resulted in an increase of the R1 diVS-ml portion and dissolution of a large part of the smectite-rich phases. The TEM-EDX approach also gave analytical proof of a sedimentary process for Di Linh smectite. The parent muscovite was altered in two different environments: (i) K-leaching and layer-wise alteration into kaolinite (weathering), and (ii) further edge-controlled alteration of mica into lath-like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite–mica intergrowths by heat impact (basalt flow).

TOURCOMP: A program for estimating end-member proportions in tourmalines

2008 ◽  
Vol 72 (5) ◽  
pp. 1021-1034 ◽  
Author(s):  
A. Pesquera ◽  
F. Torres ◽  
P. Gil-Crespo ◽  
J. Torres-Ruiz
Keyword(s):  
Structural Formula ◽  
Visual Basic ◽  
Algebraic Model ◽  
Basic Program ◽  
Apple Computer ◽  
Normalization Procedure ◽  
Error Sources ◽  
Chemical Complexity ◽  
Structural Formulae ◽  
End Members

AbstractA Visual Basic program (TOURCOMP) has been written to recast the tourmaline composition into end-member components from electron microprobe data or more complete tourmaline analyses. TOURCOMP is a program based on a linear algebraic model that directly calculates the end-member proportions of tourmalines from their structural formulae. The program is developed for IBM-compatible personal computers running under the Windows™ operating system. The source code has been also translated and compiled in order to run on an Apple computer. Analytical problems, uncertainties concerning site occupancies, and the normalization procedure to determine the structural formula are the main error sources. However, the method of recalculating tourmaline end-members presented in this paper is considered to provide reasonably good results, bearing in mind the chemical complexity of tourmaline.

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