The Zhidoy massif of ultrabasic-alkaline rocks and carbonatites: its geochemical features, sources and ore potential.

2020 ◽  
Author(s):  
Nikolai Vladykin ◽  
Natalia Alymova
Keyword(s):  
Main Type ◽  
Geological Structure ◽  
Primary Magma ◽  
Alkaline Rocks ◽  
Rare Elements ◽  
Mantle Sources ◽  
Spider Diagrams ◽  
Ore Potential

<p> The article describes geological structure of Jidoi massif and its age. The scheme of the massif magmatism has been constructed. Double correlation plots of petrogenic elements of rocks of the massif in which the unified trend of rock structures is observed, are given for verification of correctness of the scheme of magmatism. Spectra of TR and spider diagrams of concentrations of rare elements in rocks of the massif are given. Piroxenites, early rocks of the massif are ores on titanium. Titanium concentrates in three minerals: titanomagnetite, ilmenite and perovskite. The main type of titanium ores is perovskitic type, it is known only in Jidoi massif. Mantle sources of primary magma of the massif is concluded on the basic of geochemistry of isotopes of Sr and Nd. </p>

Caledonian magmatism record within Hebridean Terrane? Loch Roag dyke (Lewis Island, northern Scotland) non-peridotitic xenoliths and megacrysts as messengers from deep lithosphere.

2020 ◽  
Author(s):  
Daniel Buczko ◽  
Magdalena Matusiak-Małek ◽  
Brian J. G. Upton ◽  
Theodoros Ntaflos ◽  
Sonja Aulbach ◽  
...  
Keyword(s):  
North Atlantic ◽  
Parental Magma ◽  
Geological Structure ◽  
Trace Element Composition ◽  
Isotopic Ratios ◽  
The North ◽  
Source Regions ◽  
Mantle Sources ◽  
History Of ◽  
North Atlantic Craton

<p>The northernmost part of Scotland – the Hebridean Terrane – is formed of Archean rocks originally being part of the Laurentian North Atlantic Craton. The geological history of the terrane is well recognised, however details of its internal structure remain unknown. The Eocene (Faithfull et al. 2012, JGS) Loch Roag monchiquite (Lewis Island) sampled deep-seated lithologies, providing insight on evolution and geological structure of the deeper lithosphere of the Hebridean terrane. The monchiquite comprises abundant xenoliths of ultramafic, mafic and felsic rocks. The peridotitic xenoliths represent pieces of Archean mantle underlying marginal parts of the North Atlantic Craton, whereas the origin of non-peridotitic lithologies is uncertain.</p><p>The studied suite of samples comprises two groups: 1) “xenoliths” of diorites (plagioclase, clinopyroxene, orthopyroxene, apatite, opaques) and biotite clinopyroxenites (+apatite), 2) “megacrysts” of clinopyroxene and K-feldspar, both with inclusions of clinopyroxene, biotite and apatite. Megacrysts of alkali-rich feldspar associated with corundum and HFSE-bearing minerals, and composite xenoliths formed of pyroxenite and K-feldspar-rich lithology have also been described from this locality (Menzies et al., 1986, Geol. Soc. Australia Spec. Pub.; Upton et al., 2009, Mineral. Mag.).</p><p>We interpret the “xenoliths” as products of crystallization of fractionated mafic melt(s). The primary character of Sr isotopic ratios in plagioclase (<sup>87</sup>Sr/<sup>86</sup>Sr <0.702) suggests that parental melt of those lithologies originated from melting of depleted lithospheric mantle sources. The “megacrysts” represent fragments of disintegrated alkaline pegmatite(s) formed from melt of plausible mantle origin, possibly enriched (<sup>87</sup>Sr/<sup>86</sup>Sr in feldspar >0.704).</p><p>Trace element composition, similar Sr isotopic ratios of minerals and textural features of “xenoliths” and “megacrysts” groups suggest their close genetic relationship. This geochemical resemblance may reflect crystallisation from primarily similar melt(s) and source regions affected by similar metasomatism. Petrographic features observed in rocks described by Upton et al., (2009) imply that the parental magma of megacrysts might have intruded the rocks forming the xenoliths group. Moreover, the Rb-Sr ages of xenoliths (Der-Chuen et al., 1993, GCA) indicate crystallisation during (or shortly after) Caledonian orogeny. Preliminary age relationship between groups will be determined by on-going Rb-Sr dating of megacrysts.</p><p>Xenoliths similar to diorites from Loch Roag were reported by Badenszki et al. (2019, JoP) from the Midland Valley terrane (“metadiorites” of protolith ages ca. 415 Ma). They were interpreted as products of alkaline syn-/post-collisional Caledonian magmatism. Our study shows that non-peridotitic xenoliths from Loch Roag dyke might represent a record of similar (or the same) magmatism in the northernmost, “Laurentian” part of Scotland. This study presents the first report of such Caledonian magmatism record within the Hebridean Terrane.</p><p>Founded by Polish National Science Centre grant no. UMO-2016/23/B/ST10/01905, part of the data was obtained thanks to the Polish-Austrian project no. WTZ PL 08/2018.</p>

scholarly journals The Ilímaussaq batholith. A review and discussion

1958 ◽  
Vol 19 ◽  
pp. 1-48
Author(s):  
H Sørensen
Keyword(s):  
Field Data ◽  
Country Rock ◽  
Metasomatic Rock ◽  
Field Work ◽  
Present Knowledge ◽  
Primary Magma ◽  
Field Observations ◽  
Alkaline Rocks ◽  
Two Stages ◽  
Later Phase

The Ilímaussaq batholith was examined and described in a masterly way by N.V. Ussing in the first years of this century. During the last few years, the region has been re-examined and this work is still being carried out. It is based on maps far superior to those used by Ussing. This paper is a summary of the present knowledge of the geology of the batholith. Ilímaussaq is one of many plutonic bodies in the alkaline province of South Greenland. Its formation was preceded by the accumulation of sandstone, extrusion of lavas, and block movements. The country rock consists of granite. Ussing divided the plutonic rocks of Ilímaussaq into two groups: 1) the unstratified complex made up of fairly normal rocks as augite syenite, essexite, nordmarkite, and arfvedsonite granite ; 2) the stratified, peralkaline, agpaitic nepheline syenites: sodalite foyaite, naujaite, kakortokite, and lujavrite. These rocks are often rich in sodalite and eudialyte. The marginal borders of the batholith are transgressive. The agpaites are overlain by almost horizontal beds of porphyries. The stratified part of the complex is saucer-shaped. According to Ussing the batholith was formed in two stages; in the first stage the unstratified rocks crystallized, in the second the agpaites were intruded and partially replaced the unstratified rocks. The differentiation of the agpaites has later been discussed by Fersman and Backlund. Wegmann considered the nepheline syenites to be of metasomatic origin. The Ilímaussaq batholith is compared with other regions of alkaline rocks. On this basis and in the light of new field data the magmatic and metasomatic modes of formation of the batholith are discussed. Much more field work is, however, still necessary before more final conclusions can be reached. In addition to Ussing’s interpretation of the genesis of the batholith a somewhat different magmatic explanation is put forward. Augite syenite is considered to be the primary magma. A part of this magma was trapped under an impermeable roof and huge amounts of volatiles were accumulated in the magma during its crystallization, especially in its upper part (cf. Sather, 45). The sodalite-rich naujaite crystallized in the upper part of the magma, the banded kakortokite at a deeper level. In a later phase, subsidence of parts of the batholith occurred and at this stage the melanocratic and schistose lujavrite was formed. This rock can be compared with tinguaites and may then be considered to be magmatic, but it may also be regarded as a metasomatic rock especially formed in the most deformed parts of the complex. Wegmann’s view that essexite, nordmarkite and porphyries are metasomatically transformed into nepheline syenites is discussed. It is supported by the finding of a pillow structure in the lujavrite. As an alternative the writer suggests that the metasomatism has acted upon an older plutonic body made up of augite syenite and foyaite, etc. In the writer's opinion the combination of magmatic and metasomatic processes is in best agreement with the field observations.

Main Features Of Ore Potential And Statistical Metallogenic Assessment Of The Zeravshan-Alay Belt (South Tian-Shan)

2020 ◽  
Vol 02 (12) ◽  
pp. 50-60
Author(s):  
Odiljon Takhirdjanovich Razikov ◽  
◽  
Saodat Torexanovna Maripova ◽  
◽  
◽  
...  
Keyword(s):  
Geological Structure ◽  
Gis Technology ◽  
History Of Development ◽  
Metallogenic Belt ◽  
History Of ◽  
Ore Potential ◽  
Tian Shan

This work reflects the geological structure, history of development and ore content of the Zirabulak-Ziaetda and Kuldzhuktau ore-bearing complexes. The types of placement of structures are considered: focal-zonal, belt, nodal and frame-nodal. In the Zeravshan-Alai metallogenic belt, regularities have been established for the distribution of endogenous mineralization of ore regions and provinces. A metallogenic map was compiled using GIS technology using statistical analyzes to identify promising areas

Geology, mineral associations, and composition of native gold in mineral deposits of Taimyr–Severnaya Zemlya Orogen

2019 ◽  
Vol 484 (1) ◽  
pp. 71-76
Author(s):  
V. F. Proskurnin ◽  
G. A. Palyanova ◽  
A. V. Gavrish ◽  
B. S. Petrushkov ◽  
A. A. Bagaeva ◽  
...  
Keyword(s):  
Component Composition ◽  
Geological Structure ◽  
Gold Ore ◽  
Grain Sizes ◽  
Mineral Associations ◽  
Ore Mineralization ◽  
Chemical Conditions ◽  
Severnaya Zemlya ◽  
Physical And Chemical ◽  
Ore Potential

Diverse grain sizes and morphologies, chemical composition, and productive mineral associations of native Au from new mineralizations within two mineragenic areas (Mininsk–Bolshevik miogeocline, Shrenk–Faddeev accretionary) in Western and Central Taymyr, are indicative of a complex, multi-component composition of ore-forming systems and differences in the physical and chemical conditions of formation of gold ore mineralization. The obtained data on the characteristics of native Au, combined with peculiarities of the geological structure of the objects, suggest a significant gold ore potential of central sector of the Russian Arctic.

scholarly journals Isotopic evidence for a lithospheric origin of alkaline rocks and carbonatites: an example from southern Africa

2016 ◽  
Vol 53 (11) ◽  
pp. 1216-1226 ◽  
Author(s):  
Lewis D. Ashwal ◽  
Madelein Patzelt ◽  
Mark D. Schmitz ◽  
Kevin Burke
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Alkaline Rock ◽  
Time Span ◽  
Mantle Lithosphere ◽  
Alkaline Rocks ◽  
Isotopic Compositions ◽  
Magmatic Rocks ◽  
Mantle Sources ◽  
Source Component

Alkaline rocks and carbonatites, including nepheline syenites, are well established as mantle-derived magmatic products, but the nature and location of their mantle sources is debated. Some workers have used isotopic compositions to infer mixed mantle plume type sources such as EM1, HIMU, and FOZO, implying derivation from the subcontinental asthenosphere. Other models favour an entirely lithospheric source, whereby the magmas, originally formed during intracontinental rifting, became deformed and subducted into the mantle lithosphere during later continental collisions, and constituted part of a source component for later rift-related alkaline and carbonatite magmatism. We tested this model using Sr, Nd, and Hf isotopic compositions of deformed and undeformed nepheline syenites and carbonatites from three occurrences in southern Africa, representing emplacement over a ∼1 Ga time span. These include Bull’s Run, South Africa (1134 Ma); Tambani, Malawi (726 Ma); and the Chilwa Alkaline Province, Malawi (130 Ma). Mixing modelling indicates that the isotopic compositions of the early Cretaceous Chilwa samples can be accounted for if their source consisted of a blend of ∼99% depleted subcontinental mantle lithosphere and ∼0.5%–1% of a subducted component similar to the Neoproterozoic Bull’s Run nepheline syenites. We do not consider the Bull’s Run material specifically as the component involved in the Chilwa source, but our model illustrates an example of how recycled, older, alkaline magmatic rocks can contribute to the mantle sources of younger alkaline rock and carbonatite magmatism. This model accounts for the observation of recurrent alkaline rock and carbonatite magmatism over hundreds of millions of years in spatially restricted areas like southern Africa. Carbonatite and related alkaline magmatic rocks, therefore, need not owe their origin to deep, sublithospheric melting processes.

Petrology of the ultramafic lamprophyre and associated rocks at Coral Rapids, Abitibi River, Ontario

1994 ◽  
Vol 31 (8) ◽  
pp. 1325-1334
Author(s):  
A. D. Edgar ◽  
L. A. Pizzolato ◽  
G. M. Butler
Keyword(s):  
Rock Type ◽  
Metamorphic Rocks ◽  
Alkaline Rocks ◽  
Rock Types ◽  
Ultramafic Lamprophyre ◽  
Mantle Sources ◽  
Host Rocks ◽  
Uniform Composition ◽  
West Eifel ◽  
Metasomatized Mantle

An ultramafic lamprophyre sill and dikes, and an olivine–melilite-rich dike rock intrude Lower to Middle Devonian sediments and low- to high-grade Archean metamorphic rocks on the west bank of the Abitibi River, Coral Rapids, Ontario. Although previously considered to be kimberlitic, all these rocks contain olivine + clinopyroxene + phlogopite ± melilite, and hence are ultramafic alkaline rocks. The ultramafic lamprophyre can be distinguished from the dike by its lower SiO2, Na2O, Al2O3, and higher MgO and FeO. In contrast the olivine–melilite dike rock has a more uniform composition, characteristically contains melilite, and has higher Cr and Ni contents. Enriched light rare earth element (LREE) chondrite-normalized patterns are similar for all rocks.Olivine, clinopyroxene, and phlogopite have Mg# (Mg# = 100 Mg/(Mg + Fe) mol) typical of minerals in primitive alkaline rocks. Melilite composition is similar to that of igneous melilites. Phlogopites in all rock types are enriched in Ba and F and the degree of enrichment is distinct for each rock type. Accessory minerals include apatite, carbonates, chlorite, sericite, and sodalite (only in the olivine–melilite-bearing rock).The mineralogy and chemistry of the Coral Rapids rocks suggest that they are derived from a primitive olivine melilitite magma that may have evolved by fractionation of small amounts of olivine and clinopyroxene to form these alkaline ultramafic magmas.Xenoliths in the ultramafic lamprophyre sill and in lesser abundance in the olivine–melilite dike rock include olivine, phlogopite, and clinopyroxene-rich mantle-derived assemblages. The similarity between these xenoliths and their host rocks at Coral Rapids and those from southwest Uganda and West Eifel, Germany, suggests that the Coral Rapids rocks may be derived from magmas that originated from metasomatized mantle sources.

ESTIMATION OF THE ABUNDANCE AND DISTRIBUTION OF RARE EARTH ELEMENTS IN SOIL AROUND KADUNA REFINING AND PETROCHEMICAL COMPANY USING NUCLEAR TECHNIQUE

2020 ◽  
Vol 4 (2) ◽  
pp. 599-604
Author(s):  
Michael A. Onoja ◽  
P. H. Bukar ◽  
C. U. Omeje ◽  
A. M. Adamu
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Nuclear Technique ◽  
Flood Plains ◽  
Economic Exploitation ◽  
Rare Elements ◽  
Petrochemical Company ◽  
The Moment ◽  
Abundance And Distribution ◽  
Natural Pattern

Instrumental neutron activation analysis (INAA) technique was used to investigate the abundance and distribution of rare earth elements (REE) in soil around Kaduna Refinery. The aim of the study is to assess the rare elements potential of Nigeria for economic exploitation. Five REEs (La, Dy, Eu, Yb, and Lu) were detected in varying concentrations ranging from a minimum of 0.6 µg/g (Lu) to a maximum of 249.0 µg/g (La). The elements existed with trends consistent with the natural pattern of REEs in soil, showing significant Eu and Dy anomalies which characterize upper plains and flood plains. The levels of REEs in soil in the study area were generally slightly above background levels, with minimal (La, Dy, and Eu), moderate (Yb), and significant (Lu) enrichments and trending: Lu ˃Yb ˃ Eu ˃ Dy ˃ La. The abundance of the REEs investigated cannot establish a potential of Nigeria for economic exploitation of the mineral, hence, rare earth project in the study area is not viable at the moment.

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