scholarly journals Mineralogy and Geochemistry of Ocelli in the Damtjernite Dykes and Sills, Chadobets Uplift, Siberian Craton: Evidence of the Fluid–Lamprophyric Magma Interaction

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 724
Author(s):  
Anna A. Nosova ◽  
Ludmila V. Sazonova ◽  
Alexey V. Kargin ◽  
Elena O. Dubinina ◽  
Elena A. Minervina
Keyword(s):  
Siberian Craton ◽  
Potassium Feldspar ◽  
Magmatic Fluid ◽  
Geochemical Signature ◽  
Ree Mobility ◽  
Ree Patterns ◽  
Silicate Carbonate ◽  
Ree Pattern ◽  
Highly Evolved ◽  
Carbonate Melt

The study reports petrography, mineralogy and carbonate geochemistry and stable isotopy of various types of ocelli (silicate-carbonate globules) observed in the lamprophyres from the Chadobets Uplift, southwestern Siberian craton. The Chadobets lamprophyres are related to the REE-bearing Chuktukon carbonatites. On the basis of their morphology, mineralogy and relation with the surrounding groundmass, we distinguish three types of ocelli: carbonate-silicate, containing carbonate, scapolite, sodalite, potassium feldspar, albite, apatite and minor quartz ocelli (K-Na-CSO); carbonate–silicate ocelli, containing natrolite and sodalite (Na-CSO); and silicate-carbonate, containing potassium feldspar and phlogopite (K-SCO). The K-Na-CSO present in the most evolved damtjernite with irregular and polygonal patches was distributed within the groundmass; the patches consist of minerals identical to minerals in ocelli. Carbonate in the K-Na-CSO are calcite, Fe-dolomite and ankerite with high Sr concentration and igneous-type REE patterns. The Na-CSO present in Na-rich damtjernite with geochemical signature indicates the loss of the carbonate component. Carbonate phases are calcite and Fe-dolomite, and they depleted in LREE. The K-SCO was present in the K-rich least-evolved damtjernite. Calcite in the K-SCO has the highest Ba and the lowest Sr concentration and U-shaped REE pattern. The textural, mineralogical and geochemical features of the ocelli and their host rock can be interpreted as follows: (i) the K-Na-CSO are droplets of an alkali–carbonate melt that separated from residual alkali and carbonate-rich melt in highly evolved damtjernite; (ii) the Na-CSO are droplets of late magmatic fluid that once exsolved from a melt and then began to dissolve; (iii) the K-SCO are bubbles of K-P-CO2 fluid liberated from an almost-crystallised magma during the magmatic–hydrothermal stage. The geochemical signature of the K-SCO carbonate shows that the late fluid could leach REE from the host lamprophyre and provide for REE mobility.

Pyroclastic rocks from Kanchanaburi and Uthai Thani Province, Inthanon Zone, Western Thailand

2020 ◽  
Author(s):  
Suwijai Jatupohnkhongchai ◽  
Sirot Salyapongse ◽  
Burapha Phajuy ◽  
Daniela Gallhofer ◽  
Christoph Hauzenberger
Keyword(s):  
Volcanic Rocks ◽  
Potassium Feldspar ◽  
Geochronological Data ◽  
Rock Composition ◽  
Pyroclastic Rocks ◽  
Eu Anomaly ◽  
Geologic Map ◽  
Ree Patterns ◽  
First Time ◽  
Strong Depletion

<p>A series of pyroclastic rocks are mapped as a Silurian-Devonian unit in the Kanchanaburi-Uthai Thani area, Western Thailand, which belongs to the Inthanon Zone. These pyroclastic rocks were discovered and described for the first time in 1977 and mentioned in the 1:250,000 Suphanburi geologic map sheet and report. Since then these rocks were poorly investigated and their formation and geotectonic setting is unclear. As a result, we report petrographic, geochemical and geochronological data of these pyroclastic rocks. Petrographically, the pyroclastic rocks can be described as a meta-quartz-K-feldspar crystal tuff, a meta-quartz crystal tuff, and a meta-lithic tuff. They are made up of mm sized clasts in a finely grained matrix. The clasts consist of potassium feldspar, rounded quartz, embayed quartz, trachytic and metasedimentary rock clasts embedded in a highly altered devitrified fine-ash matrix containing sericite.</p><p>The whole-rock composition shows enrichments in SiO<sub>2</sub> and K<sub>2</sub>O and a strong depletion in CaO and Na<sub>2</sub>O which is related to late alteration of the volcanoclastic rocks. Based on the immobile element classification plot of Pearce 1996, the tuffs can be classified as trachyandesite, trachyte, dacite and rhyolite. Their chondrite-normalized REE patterns display light REE enrichment with nearly flat heavy REE and a negative Eu anomaly, typical for calcalkaline volcanic rocks. Most samples fall in the volcanic arc granites field in the granite discrimination diagrams of Pearce 1984.</p><p>Zircons extracted from the tuffs will be used to constrain their crystallization age by U-Pb LA-MCICPMS dating. This allows us to constrain the age of formation and to place this in context with the closure of the Paleotethys.</p>

Highly evolved juvenile granites with tetrad REE patterns: the Woduhe and Baerzhe granites from the Great Xing'an Mountains in NE China

Lithos ◽  
2001 ◽  
Vol 59 (4) ◽  
pp. 171-198 ◽  
Author(s):  
Bor-ming Jahn ◽  
Fuyuan Wu ◽  
R. Capdevila ◽  
F. Martineau ◽  
Zhenhua Zhao ◽  
...  
Keyword(s):  
Ne China ◽  
Great Xing’An Mountains ◽  
Ree Patterns ◽  
Highly Evolved

P-T-fluid conditions of mineral equilibria in garnet-biotite crustal xenoliths from the Yubileinaya and Sytykanskaya kimberlite pipes, Yakutian kimberlite province.

2021 ◽  
Author(s):  
Natalia Seliutina ◽  
Oleg Safonov ◽  
Vasiliy Yapaskurt ◽  
Dmitry Varlamov ◽  
Igor Sharygin ◽  
...  
Keyword(s):  
Water Activity ◽  
Siberian Craton ◽  
Database Systems ◽  
Potassium Feldspar ◽  
Coarse Grained ◽  
Chemical Compositions ◽  
Exchange Reactions ◽  
Russian Science ◽  
Isotopic Evidence ◽  
Crustal Xenoliths

<p>This study provides the results of research of the garnet-biotite crustal xenoliths from the Yubileinaya (372±4.8 Ma) and Sytykanskaya (363±13 Ma) kimberlite pipes of the Alakit-Markhinsky field (Siberian craton). Isotopic evidence on zircons from similar crustal xenoliths (Grt+Bt+Pl+Kfs+Qtz±Scp) showed Archean Hf model ages (TDM = 3.13-2.5 Ga) and thus indicated that most of the lower and middle crust beneath the Markha terrane was produced in the Archean time (Shatsky et al., 2016).</p><p>The xenoliths are represented by the assemblage Grt+Bt+Pl+Kfs±Opx. Quartz is present only as rare inclusions in garnets. The rocks are coarse-grained, slightly foliated with garnets porphyroblasts of up to 5 cm in size. A spectacular feature of the rocks is an abundance of K-feldspar. Garnet grains are almost compositionally homogeneous, although they show a rimward decrease of the Mg and Ca contents indicating exchange reactions during cooling. Biotites are characterized by high F increasing from 1.5 wt.% in cores up to 2.2 wt.% in rims, as well as TiO<sub>2</sub> up to 7.8 wt.%, which is typical for high-grade rocks. Orthopyroxene (up to 5.5 wt. % Al<sub>2</sub>O<sub>3</sub>) relics are preserved both as inclusions in garnet and as individual grains in the rock matrix. Plagioclase occurs both as separate grains and as lamellae in potassium feldspar.</p><p>The bulk chemical compositions correspond to a metagraywacke. The REE spectra in these rocks are rather flat with slight enrichment in LREE. All the studied rocks are characterized by a distinct negative Eu anomaly (Eu/Eu* = 0.31-0.45).</p><p>Calculations using the PERPLEX software version 6.7.6 (Connolly, 2005) for Mg and Ca in Grt, Mg in Bt, and Ca in Pl indicated temperatures 630-730°C and pressures 5.8-7.2 kbar for the rocks. However, equilibria involving Al<sub>2</sub>O<sub>3</sub> in orthopyroxene corresponds to temperatures of 750-800<sup>o</sup>С at a similar pressure. It indicates that metamorphism of the garnet-biotite rocks reached higher temperatures, but they were actively modified later during cooling and insignificant decompression (by about 1 kbar). Calculations using the TWQ software version 2.3 (Berman, 2007) indicate consistent temperatures 610-680°C for the garnet-orthopyroxene and 640-690<sup>o</sup>C for garnet-biotite Mg-Fe exchange equilibria. Calculations using the Grs+2Prp+Kfs+H<sub>2</sub>O=Phl+3En+3An equilibrium demonstrated water activity below 0.1. Such low water activity could indicate an influence of highly concentrated alkaline Cl-F-bearing brines. This assumption is confirmed by extensive development of potassium feldspar, absence of quartz in the matrix, and elevated Cl contents of biotite, 0.1-0.3 wt. % at high #Mg (>0.7) and F content.</p><p><em>The study is supported by the Russian Science Foundation project 18-17-00206.</em></p><p><strong> </strong><strong>References </strong></p><p>Berman, R. G. (2007). winTWQ (version 2.3): a software package for performing internally-consistent thermobarometric calculations. Geological survey of Canada, open file, 5462, 41.</p><p>Connolly, T. M., & Begg, C. E. (2005). Database systems: a practical approach to design, implementation, and management. Pearson Education.</p><p>Shatsky, V. S., Malkovets, V. G., Belousova, E. A., ... & O’Reilly, S. Y. (2016). Tectonothermal evolution of the continental crust beneath the Yakutian diamondiferous province (Siberian craton): U–Pb and Hf isotopic evidence on zircons from crustal xenoliths of kimberlite pipes. Precambrian Research, 282, 1-20.</p>

Geochemistry of Cretaceous subduction initiation related cumulate gabbros in a forearc setting from Chaldoran ophiolite, NW Iran

2020 ◽  
Author(s):  
Mahleqa Rezaei ◽  
Mohssen Moazzen ◽  
Tian-Nan Yang
Keyword(s):  
Source Region ◽  
Mineral Chemistry ◽  
Ultramafic Rocks ◽  
Nw Iran ◽  
Subduction Initiation ◽  
Rock Types ◽  
Original Magma ◽  
Ree Patterns ◽  
Ree Pattern ◽  
Cretaceous Subduction

<p>The Neo-Tethys-related Chaldoran ophiolite in NW Iran and at the Turkish border is a part of the larger Khoy ophiolite. Cumulate and isotropic gabbro along with serpentinized peridotite, pillow basalt, pelagic limestone, rare radiolarites, and volcano-sedimentary units are the main rock types in the area. The gabbros occur as lenses with ultramafic rocks, or as relatively large exposures with fault contact with ultramafic rocks. In this study, we provide new whole-rock geochemistry, mineral chemistry and zircon U/Pb age for the cumulate gabbros from the Chaldoran area. Gabbros have tholeiitic composition and are highly depleted. Chondrite normalized rare earth elements (REE) pattern for gabbros are comparative with REE patterns for N-MORB, but overall with more depleted features. The N-MORB normalized multi-elements pattern shows high depletion in HREE and HFSE and enrichment in some LREE and LILEs. Negative anomaly for some HFSE relative to N-MORB, along with enrichment in LILE for the samples indicates the source region as subduction influenced mantle. The cumulated gabbro whole rock and Clinopyroxenes geochemistry indicate an intra-oceanic forearc setting for the studied samples. They also have many similarities to boninite in mineral and whole rock geochemistry. U-Pb zircon dating of the gabbro samples indicates 95.3-114.1 Ma ages for the generation of the gabbros parent magma. The original magma was related to the later stages of the forearc setting in the subduction initiation (SI) stage. This ‘SI’ related Albian-Cenomanian the Chaldoran depleted gabbro likely are the continuation of Taurus SI related late Cretaceous ophiolite complexes in Turkey.</p>

Application of a Selective Phase Extraction Procedure to Samples from the Adamello Contact Aureole (Italy)

1994 ◽  
Vol 353 ◽  
Author(s):  
T. E. Payne ◽  
G. R. Lumpkin ◽  
P. J. McGlinn ◽  
K. P. Hart
Keyword(s):  
Rare Earth ◽  
Alpha Spectrometry ◽  
Country Rock ◽  
Extraction Procedure ◽  
Contact Aureole ◽  
Phase Extraction ◽  
Rich Phase ◽  
Ree Patterns ◽  
Ree Pattern ◽  
Hydrothermal Veins

AbstractHydrothermal veins, rich in Ti, Zr, rare earth elements (REE’s), and actinides, occur in the pure dolomitic marbles of the Adamello contact metamorphic aureole. A selective phase extraction using 9M HC1 was applied to samples from within and near these veins to chemically separate acid-soluble phases from residual phases, and to study the associations of U, Th, and REE’s with these phases. The samples were from the phlogopite, titanian clinohumite, and forsterite vein zones, and from the country rock. The effects of the extraction were studied by SEM/EDS and by chemical analysis. Isotopes of U and Th were analysed by alpha-spectrometry.The chemical data and SEM/EDS results indicated that dolomite, calcite, apatite, and much of the pyrrhotite were dissolved by the 9M HC1, whereas spinel, phlogopite, titanite, chal copy rite, and zirconolite were among the acid-resistant phases. In all vein samples, the REE-patterns of acid-soluble phases were consistent with the dissolution of REE-rich apatite. In samples from the phlogopite zone, the majority of U, Th, and REE’s were in residual phases, and the REE pattern of the residue was similar to that of REE-rich titanite. In the titanian clinohumite zone, a substantial proportion of these elements were in acid-soluble phases, and the REE pattern of the residual phases resembled that of zirconolite. Clinohumite was partially dissolved by the HC1 treatment. The sample from the forsterite zone contained substantial amounts of REE's in acid-soluble phases, whereas Th and U were mostly in residual phases. The dolomite (country rock) samples contained small amounts of an acid-resistant, uranium-rich phase which, while only comprising about 0.2% of the mass, accounted for 40–60% of the uranium present.

scholarly journals Pyroxenite as a Product of Mafic-Carbonate Melt Interaction (Tazheran Massif, West Baikal Area, Russia)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 654
Author(s):  
Eugene V. Sklyarov ◽  
Andrey V. Lavrenchuk ◽  
Anna G. Doroshkevich ◽  
Anastasia E. Starikova ◽  
Sergei V. Kanakin
Keyword(s):  
Partial Melting ◽  
Lake Baikal ◽  
Lower Crust ◽  
Silicate Melts ◽  
Magmatic System ◽  
Crystallization Point ◽  
Carbonate Material ◽  
Silicate Carbonate ◽  
Carbonate Melt

Pyroxenite and nepheline-pyroxene rocks coexist with dolomite-bearing calcite marbles in Tazheran Massif in the area of Lake Baikal, Siberia, Russia. Pyroxenites occur in a continuous elongate zone between marbles and beerbachites (metamorphosed gabbro dolerites) and in 5 cm to 20 m fragments among the marbles. Pyroxene in pyroxenite is rich in calcium and alumina (5–12 wt% Al2O3) and has a fassaite composition. The Tazheran pyroxenite may originate from a mafic subvolcanic source indicated by the presence of remnant dolerite found in one pyroxenite body. This origin can be explained in terms of interaction between mafic and crust-derived carbonatitic melts, judging by the mineralogy of pyroxenite bodies and their geological relations with marbles. According to this model, the intrusion of mantle mafic melts into thick lower crust saturated with fluids caused partial melting of silicate-carbonate material and produced carbonate and carbonate-silicate melts. The fassaite-bearing pyroxenite crystallized from a silicate-carbonate melt mixture which was produced by roughly synchronous injections of mafic, pyroxenitic, and carbonate melt batches. The ascending hydrous carbonate melts entrained fragments of pyroxenite that crystallized previously at a temperature exceeding the crystallization point of carbonates. Subsequently, while the whole magmatic system was cooling down, pyroxenite became metasomatized by circulating fluids, which led to the formation of assemblages with garnet, melilite, and scapolite.

scholarly journals Compositional Variability of Monazite–Cheralite–Huttonite Solid Solutions, Xenotime, and Uraninite in Geochemically Distinct Granites with Special Emphasis to the Strongly Fractionated Peraluminous Li–F–P-Rich Podlesí Granite System (Erzgebirge/Krušné Hory Mts., Central Europe)

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 127
Author(s):  
Karel Breiter ◽  
Hans-Jürgen Förster
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Solid Solutions ◽  
Heavy Rare Earth Elements ◽  
Compositional Variability ◽  
Variscan Granites ◽  
Almost All ◽  
Ree Pattern ◽  
Highly Evolved ◽  
Comprehensive Study

A comprehensive study of monazite–cheralite–huttonite solid solutions (s.s.) and xenotime from the highly evolved, strongly peraluminous P–F–Li-rich Podlesí granite stock in the Krušné Hory Mts., Czech Republic, indicates that, with the increasing degree of magmatic and high-T early post-magmatic evolution, the content of the cheralite component in monazite increases and the relative dominance of middle rare earth elements (MREE) in xenotime becomes larger. Considering the overall compositional signatures of these two accessory minerals in the late Variscan granites of the Erzgebirge/Krušné Hory Mts., three types of granites can be distinguished: (i) chemically less evolved F-poor S(I)- and A-type granites contain monazite with a smooth, mostly symmetric chondrite-normalized (CN) rare-earth elements (REE) pattern gradually declining from La to Gd; associated xenotime is Y-rich (˃0.8 apfu Y) with a flat MREE–HREE (heavy rare earth elements) pattern; (ii) fractionated A-type granites typically contain La-depleted monazite with Th accommodated as the huttonite component, combined with usually Y-poor (0.4–0.6 apfu Y) xenotime characterized by a smoothly inclining, Yb–Lu-dominant CN-REE pattern; (iii) fractionated peraluminous Li-mica granites host monazite with a flat, asymmetric (kinked at La and Nd) CN-LREE pattern, with associated xenotime distinctly MREE (Gd–Tb–Dy)-dominant. Monazite and xenotime account for the bulk of the REE budgets in all types of granite. In peraluminous S(I)-type granites, which do not bear thorite, almost all Th is accommodated in monazite–cheralite s.s. In contrast, Th budgets in A-type granites are accounted for by monazite–huttonite s.s. together with thorite. The largest portion of U is accommodated in uraninite, if present.

scholarly journals The Syenite–Carbonatite Complex of Ihouhaouene (Western Hoggar, Algeria): Interplay Between Alkaline Magma Differentiation and Hybridization of Cumulus Crystal Mushes

2021 ◽  
Vol 8 ◽  
Author(s):  
A. Djeddi ◽  
F. Parat ◽  
J.-L. Bodinier ◽  
K. Ouzegane ◽  
J.-M. Dautria
Keyword(s):  
Alkaline Complex ◽  
Carbonatite Complex ◽  
Slow Cooling ◽  
Silicate Minerals ◽  
Rock Types ◽  
Evolutionary Scheme ◽  
Silicate Liquids ◽  
Rock Suite ◽  
Highly Evolved ◽  
Carbonate Melt

The 2 Ga-old Ihouhaouene alkaline complex (Western Hoggar, Algeria) is among the oldest known carbonatite occurrences on Earth. The carbonatites are calciocarbonatites hosted by syenites, the predominant rock type in the complex. Both rock types are characterized by medium-grained to pegmatitic textures and contain clinopyroxene, apatite, and wollastonite, associated with K-feldspar in syenites and a groundmass of calcite in carbonatites. The rock suite shows a continuous range of compositions from 57–65 wt.% SiO2 and 0.1–0.4 wt.% CO2 in red syenites to 52–58 wt.% SiO2 and 0.1–6.5 wt.% CO2 in white syenites, 20–35 wt.% SiO2 and 11–24 wt.% CO2 in Si-rich carbonatites (>10% silicate minerals), and <20 wt.% SiO2 and 24–36 wt.% CO2 in Si-poor carbonatites (<5% silicate minerals). Calculation of mineral equilibrium melts reveals that apatite and clinopyroxene are in disequilibrium with each other and were most likely crystallized from different parental magmas before being assembled in the studied rocks. They are subtle in the red syenites, whereas the white syenites and the Si-rich carbonatites bear evidence for parental magmas of highly contrasted compositions. Apatite was equilibrated with LREE-enriched (Ce/Lu = 1,690–6,182) carbonate melts, also characterized by elevated Nb/Ta ratio (>50), whereas clinopyroxene was precipitated from silicate liquids characterized by lower LREE/HREE (Ce/Lu = 49–234) and variable Nb/Ta ratios (Nb/Ta = 2–30). The Si-poor carbonatites resemble the Si-rich carbonatites and the white syenites with elevated REE contents in apatite equilibrium melts compared to clinopyroxene. However, apatite equilibrium melt in Si-poor carbonatite shows a majority of subchondritic values (Nb/Ta<10) and clinopyroxene has chondritic-to-superchondritic values (Nb/Ta = 15–50). Although paradoxical at first sight, this Nb-Ta signature may simply reflect the segregation of the carbonatite from highly evolved silicate melts characterized by extremely low Nb/Ta values. Altogether, our results suggest an evolutionary scheme whereby slow cooling of a silico-carbonated mantle melt resulted in the segregation of both cumulus minerals and immiscible silicate and carbonate melt fractions, resulting in the overall differentiation of the complex. This process was however counterbalanced by intermingling of partially crystallized melt fractions, which resulted in the formation of hybrid alkaline cumulates composed of disequilibrium cumulus phases and variable proportions of carbonate or K-feldspar.

REE Characteristic of Hydrothermal Calcite in Langdu Skarn Copper Deposit

2012 ◽  
Vol 524-527 ◽  
pp. 184-189
Author(s):  
Tao Ren ◽  
Run Sheng Han ◽  
Yu Zhao Hu
Keyword(s):  
Hydrothermal Fluid ◽  
Yunnan Province ◽  
Copper Deposit ◽  
Magmatic Fluid ◽  
Substitutional Site ◽  
Complex Species ◽  
Ion Radius ◽  
The Stability ◽  
Ree Patterns ◽  
Distribution Behavior

Langdu is one of the highest grade, skarn copper deposits in Zhongdian area, Yunnan province. The chondrite-normalized REE patterns for syn-sulfide calcite from Langdu deposit are unique, being HREE-enriched, LREE-depleted and have significant positive Eu anomalies. REEs could derive from magmatic fluid exsolved from near melt. This distribution behavior is predominately constricted by REE patterns of hydrothermal fluid and the stability of complex in solutions than crystallographic factors. The DREE are increase with the decrease of ion radius. The optimum ion radius of substitutional site for REEs in the hydrothermal calcites is 0.1032nm. Eu occurs as Eu 2+ and complex species can explain the positive Eu anomalies

Sign in / Sign up

Export Citation Format

Share Document