Petrology of alkaline lamprophyres from the Coldwell alkaline complex, northwestern Ontario

1991 ◽  
Vol 28 (10) ◽  
pp. 1653-1663 ◽  
Author(s):  
Roger H. Mitchell ◽  
R. Garth Platt ◽  
Maureen Downey ◽  
David G. Laderoute
Keyword(s):  
Trace Elements ◽  
Single Crystals ◽  
Magma Chamber ◽  
Rare Earths ◽  
Olivine Basalt ◽  
Alkaline Complex ◽  
Northwestern Ontario ◽  
Alkali Olivine Basalt ◽  
Incompatible Trace Elements ◽  
Alkaline Lamprophyres

A suite of alkaline lamprophyre dikes emplaced in centers I and II rocks of the Coldwell alkaline complex is composed of camptonites with calcite ocelli, camptonites with quartz macrocrysts, amphibole camptonites, monchiquites, and sannaites. The camptonites are characterized by phenocrysts of olivine, aluminian pyroxene, kaersutite, and titanian ferropargasite set in a matrix of magnesian hastingsite, augite, plagioclase, biotite, magnetite, sphene, and minor nepheline. Quartz macrocrysts occur as corroded euhedral single crystals. Monchiquites are petrographically similar to the camptonites but are characterized by the presence of an isotropic groundmass. Sannaites contain aluminian and chromian diopside phenocrysts set in a matrix of ferroan pargasite, aluminian diopside, biotite, albitized plagioclase, and epidotized alkali feldspar.Major-element compositions indicate the ocellar camptonites, amphibole camptonites, and monchiquites have affinities with alkali olivine basalt and that monchiquites and camptonites are heteromorphs. None of the dikes represent primitive liquids. Poor correlations between incompatible trace elements (Sr, Ba, Nb, Zr, rare earths), together with the presence of reversely zoned and corroded phenocrysts, suggest that none of the lamprophyres represent single batches of magma. The lamprophyres are considered to be hybrid magmas, formed by the mixing of fragmented cumulates, several generations of phenocrysts, and batches of magma extracted from a continuously replenished evolving magma chamber located within the infrastructure of the complex. Quartz-bearing camptonites are considered to form by contamination of camptonites, although the source of the quartz cannot be determined.

scholarly journals Igneous stratigraphy and internal structure of the Little Minch Sill Complex, Trotternish Peninsula, northern Skye, Scotland

1991 ◽  
Vol 128 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Sally A. Gibson ◽  
Adrian P. Jones
Keyword(s):  
Internal Structure ◽  
Magma Chamber ◽  
Thermal Gradient ◽  
Olivine Basalt ◽  
Small Scale ◽  
Basalt Magma ◽  
Alkali Olivine Basalt ◽  
Modal Layering ◽  
Crustal Magma

AbstractDetailed sampling of the Little Minch Sill Complex reveals that it is composed of both single and multiple sills. These are formed of three main, genetically related units: picrite, picrodolerite and crinanite, which are the result of differentiation of an alkali-olivine basalt magma (approximately 10% MgO) in an upper-crustal magma chamber. Variations in igneous stratigraphy and the presence of internal chills in the Trotternish sills suggest that they were emplaced by multiple intrusion and subsequently differentiated in situ. Changes in petrography adjacent to pegmatite veins and textures within picrite units indicate compaction and filter-pressing were important processes after emplacement. Rhythmic layering (1 cm to 1 m thick) is conspicuous in the sills near contacts but does not involve cryptic mineral variation. Such modal layering may be more common than realised in relatively small-scale intrusions and maybe modelled in terms of in situ differentiation under conditions of significant undercooling in a changing thermal gradient at the synthetic for-sterite-diopside-anorthite eutectic.

Clinopyroxenes from the Upper Layered Series Kap Edvard Holm, East Greenland

1971 ◽  
Vol 38 (293) ◽  
pp. 49-57 ◽  
Author(s):  
R. Elsdon
Keyword(s):  
Optical Properties ◽  
Single Crystals ◽  
Olivine Basalt ◽  
Parent Magma ◽  
Chemical Compositions ◽  
Measurable Effect ◽  
Layered Series ◽  
East Greenland ◽  
X Ray ◽  
Alkali Olivine Basalt

SummaryChemical compositions, unit-cell contents, and optical properties of six clinopyroxenes from the Upper Layered Series are presented. There is a gradual enrichment in iron upwards in the intrusion although there is no measurable effect on the optical properties, possibly because of Cr variation and exsolution of Fe and Ti as oxides. The chemistry of the clinopyroxenes is consistent with crystallization from a water-rich magma of transitional nature between tholeiite and alkali-olivine basalt. X-ray oscillation photographs of single crystals reveal the presence of sub-microscopic exsolution lamellae of pigeonite, a feature consistent with the transitional nature of the parent magma. Exsolution lamellae of titanomagnetite are ubiquitous and were formed at subsolidus temperatures in response to high buffered oxygen fugacity. Comparisons are made between the properties of clinopyroxenes from the Lower, Middle, and Upper Layered Series, and the conditions of crystallization of each series.

Geochemical overview of the Ilímaussaq alkaline complex, South Greenland

2001 ◽  
pp. 35-53 ◽  
Author(s):  
John C. Bailey ◽  
Raymond Gwozdz ◽  
John Rose-Hansen ◽  
Henning Sørensen
Keyword(s):  
Trace Elements ◽  
Magma Chamber ◽  
Alkali Basalt ◽  
Alkaline Complex ◽  
Volatile Elements ◽  
Original Series ◽  
Igneous Province ◽  
Low Levels ◽  
Liquid Layering ◽  
Three Phases

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Bailey, J. C., Gwozdz, R., Rose-Hansen, J., & Sørensen, H. (2001). Geochemical overview of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 35-53. https://doi.org/10.34194/ggub.v190.5172 _______________ The Ilímaussaq alkaline complex is one of the latest members of the Mesoproterozoic Gardar igneous province. It was emplaced in three phases, (1) augite syenite, (2) alkali acid rocks and (3) the dominant agpaitic nepheline syenites. The immediate parent for the nepheline syenites is the augite syenite whose geochemical features, such as the low Zr/Nb ratio (3.7), match benmoreites from a nearby alkali basalt series. The agpaitic nepheline syenites are characterised by exceptionally high contents of Zr, Hf, Nb, Ta, REE, Th, U, Sn, Li, Be, Rb, Zn, Pb, Sb, W, Mo, As and Ga, and the volatile elements F, Cl, Br, I and S but exceptionally low levels of Ba, Sr, Co, Cu, Ni, Sc, V and Cr. Fractionation of cumulus phases with a distinctive geochemistry, such as sodalite (rich in Cl, Br, I, B), eudialyte (Zr, Hf, Nb, Ta, W, As) and arfvedsonite (Co, Sc, V, Cr), caused exhaustion of these elements in the residual magmas. The agpaitic magmas underwent extreme fractionation with the final lujavrite forming after 99% crystallisation of the augite syenite. Zirconium was apparently soluble in Ilímaussaq melts up to a concentration of c. 9000 ppm. Whole-rock analyses define a number of discrete Zr–U arrays which are restricted to certain intervals of the cumulate stratigraphy and are taken as evidence for liquid layering in the Ilímaussaq magma chamber. The distribution of the less common trace elements (Bi, Cd, Co, Ge, In, I, Hg, Sc, Se, V, W) and of the more abundant trace elements which failed to form minerals (Br, Cs, Ga, Hf, Rb, Sr) is summarised.

Mineralogic reaction zones at a calc-silicate/metapelite interface: an example of trace element mobility in a metamorphic environment

1994 ◽  
Vol 58 (391) ◽  
pp. 205-214 ◽  
Author(s):  
J. V. Owen ◽  
J. Dostal ◽  
B. N. Church
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Rare Earths ◽  
Fluid Phase ◽  
Aqueous Fluid ◽  
Silicate Rock ◽  
Element Mobility ◽  
Trace Element Mobility ◽  
Reaction Zones ◽  
Incompatible Trace Elements

AbstractMetasomatic interaction on a cm scale between calc-silicate pods and the enclosing sillimanite + biotite + tourmaline gneiss at Partridge Breast Lake, northern Manitoba, Canada, led to the development of an inner (by calc-silicate rock), hornblende-rich reaction zone and an outer, biotite-rich zone. The boundary between the reaction zones is interpreted as the original calc-silicate/metapelite interface. Compared with its metapelitic protolith, the biotite zone shows a two- to twenty-fold depletion in the concentrations of incompatible trace elements (notably the light rare earths, U, Th, Nb, Ta, Zr and Hf). In contrast, the relative concentrations of trace elements remained nearly constant during the mineralogical transformation of the calc-silicate rock to the hornblende zone. The depletion of trace elements in the biotite zone is attributed to the dissolution of accessory phases (e.g. monazite). Although stable at the metamorphic conditions (∼600–650°C at ∼ 4.5 kbar) prevalent during metasomatism, Mg-rich tourmaline is absent in the biotite zone, suggesting that either the pH or composition (e.g. the (Al + Si)/(Ca + Mg + Fe) ratio) of the aqueous fluid phase was inappropriate for the preservation of this mineral.

scholarly journals Gardar dykes north of the Igaliko Syenite Complex, southern Greenland

1985 ◽  
Vol 127 ◽  
pp. 1-24
Author(s):  
B.G.J Upton ◽  
J.G Fitton
Keyword(s):  
Magma Chamber ◽  
Convective Flow ◽  
Nepheline Syenite ◽  
Olivine Basalt ◽  
Fissure Eruption ◽  
Rift System ◽  
Extensional Stress ◽  
Stress Direction ◽  
Alkali Olivine Basalt ◽  
Main Series

An ENE-WSW trending swarm of Gardar dykes, traversing Mellemlandet and G. E Holm Nunataq is principally composed of a 'main series' with compositions ranging from alkali olivine basalt to trachyte and rhyolite, and scarcer phonolitic trachyte associates. The most basic 'main series' magmas were emplaced as several giant dykes up to 650 m wide. Synformally layered gabbroic and anorthositic cumulates are locally developed within these. At Syenitknold internal differentiation within a giant dyke gave rise to syenogabbros, layered syenite cumulates and peralkaline nepheline syenite pegmatites. A large xenolithic mass of exotic feldspathic gabbro within the syenites is ascribed to the foundering of feldspar-rich roofing facies into the underlying magma chamber. Less extreme differentiation in the same giant dyke east of Syenitknold produced syenogabbroic cumulates containing evidence for vigorous convective flow having developed in the cooling intrusion. Smaller (< 40 m wide) and younger dykes are almost invariably of more differentiated character. The commonest dykes ( < 15 m wide) are of benmoreite and trachyte. Dykes with their interiors crowded with plagioclase xenocrysts and anorthositic inclusions are referred to as 'big feldspar dykes' (B.F.D.s). While all compositions from basalt to benmoreite may be involved in the B.F.D.s, the B.F.D. character is typical of the hawaiites and mugearites. Small (typically < 1 m), scarce dykes and sills of highly silica-undersaturated types range from ultramafic lamprophyres to carbonatites. These may be representative of a compositional continuum between 36 and 2 wt % SiO2,. The main swarm is so closely similar to that seen to the WSW, extending through Tugtutoq and the Narssaq and Qagssiarssuk areas, that it is thought to be merelya faulted continuation ofthe latter. Itso, this swarm, c. 15 km across, is at least 140 km long. The magnitude and extent of this alkaline swarm and its individual components, may well be unique: it differs from other swarms (e.g. that of the roughly contemporaneous Nunarssuit-Isortoq swarm) in the size and abundance of the salic dykes within it. It was almost certainly related to extensive fissure eruption of basic to salic lavas. A clockwise change of several degrees between the orientation of early giant dykes and later differentiated dykes is related to a change in the extensional stress direction during the development of the Gardar rift system.

Determination of Trace Elements in Opium by Means of Activation Analysis

1963 ◽  
Vol 1 (3) ◽  
Author(s):  
Alexis C. Pappas ◽  
Jorolf Alstad ◽  
Gulbrand Lunde
Keyword(s):  
Trace Elements ◽  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Rare Earths ◽  
Gold Content ◽  
The Individual ◽  
Lanthanide Content ◽  
Different Origin

SummaryMany methods have been advocated for the determination of the origin of opium, but so far no research has been reported on the possibilities of such studies by means of radiochemical methods applied to the opium ash.In the present investigation the gold and lanthanide content in samples of opium ash has been studied using neutron activation analysis. The gold content was found to vary from about 0,5 to 10 ppm and the total rare earths content from about 20 to 150 ppm. Large variations are found in the distribution pattern of the individual rare earths in opium samples from different origin. The results are discussed and indicate that activation analysis may be used to indentify the origin of opium samples.

Motukoreaite, a new hydrated carbonate, sulphate, and hydroxide of Mg and Al from Auckland, New Zealand

1977 ◽  
Vol 41 (319) ◽  
pp. 389-390
Author(s):  
K. A. Rodgers ◽  
J. E. Chisholm ◽  
R. J. Davis ◽  
C. S. Nelson
Keyword(s):  
New Zealand ◽  
Olivine Basalt ◽  
Unit Cell ◽  
Rock Fragments ◽  
Alkali Olivine Basalt ◽  
Beach Rock ◽  
Wet Chemical ◽  
O 19 ◽  
Olivine Sand ◽  
Sand And Gravel

Motukoreaite occurs as relatively abundant, white, clay-like cement in both beach-rock and basaltic volcanic tuffs on the flanks of a small, extinct, late Pleistocene, basaltic cone at Brown's Island (Motukorea), within Waitemata Harbour, Auckland, New Zealand (36° 50′ S., 174° 35′ E.). The occurrence was originally recorded by Bartrum (1941) as ‘beach limestone’ found at two places of the island's shore. The beach-rock consists of a grain-supported fabric of poorly sorted, well-rounded, alkali-olivine basalt pebbles and granules, subangular to sub-rounded fresh olivine sand and abraded sand- and gravel-sized bioclasts in a colourless to pale yellow-green aphanocrystalline matrix of motukoreaite. Additional detritals include quartz, feldspar, and sedimentary rock fragments. Stereoscan examination of the surface of pieces of the cement prised from the beach-rock showed a box-work of plate-like crystals with a hexagonal form in which individuals measured about 3×3×0·02 microns (fig. 1).Wet-chemical analysis of a separate of the cement containing some 5 % quartz and traces of calcite and goethite gives SiO2 5·55, Al2O3 17·87, Fe2O3 0·73, CaO 0·92, MgO 22·98, MnO 0·70, ZnO 0·56, Na2O 0·71, K2O 0·10, CO2 9·32, SO3 10·00, H2O+ 19·62, H2O- 10·35, sum 99·41 %. The unit-cell formula using obtained unit-cell constants and measured specific gravity 1·43) is (Na0·73K0·07)∑0·80(Mg18·13Mn0·32Zn0·21)∑18·66Al11·15(CO3)6·22(SO4)3·97 (OH)51·1927·20H2O. Of several idealized formulae that may be proposed NaMg19Al12(CO3)6.5 (SO4)4(OH)54·28H2O is preferred.

scholarly journals Petrogenesis of the synplutonic high-magnesian porphyritic dykes from the mafic-granitoid plutons of the East-European Craton, Voronezh crystalline massif

2019 ◽  
Vol 64 (4) ◽  
pp. 356-371
Author(s):  
R. A. Terentiev
Keyword(s):  
Trace Elements ◽  
Magma Chamber ◽  
Earth Element ◽  
Parent Magma ◽  
Chrome Spinel ◽  
Calc Alkaline ◽  
East European ◽  
Fine Grained ◽  
Mineral Inclusions ◽  
Metasomatized Mantle

This paper documents the data on high-Mg porphyrite dykes (PDs) from the mafic to felsic (~2.09 Ma) plutons of Elan complex (EC). The low-thickness (first centimeters) synplutonic dykes are characterized by sharp straight contacts without visible chilling zones, in contrast to the larger (up to 119 m) dykes that have gradual transitions. The dykes are fresh, porphyritic (bronzite, Al-enstatite, labradorite) and has fine-grained mainly quartzo-feldspathic (+biotite, sulfides, accessories, ±hypersthene) matrix. Based on geochemistry data the PDs are intermediate rocks (SiO2 = 58.9–60.3 wt. %) and plot into calc-alkaline series with high magnesian of whole rock (Mg# ~0.7) and felsic (68.9–70.2 wt. %) matrix (Mg# ~0.5). The PDs show differentiated rare-earth element patterns with negligible Eu anomalies. The bronzite phenocrysts varying sizes are characterized by block zoning and contain irregular inclusions of olivine (Mg# ~0.85), clinopyroxene (Mg# ~0.88), phlogopite (Mg# up to 0.94), labradorite, chrome spinel, graphite and sulfides. The Al-enstatite phenocrysts are practically sterile with respect to trace elements and mineral inclusions. The geochemical features as well as diffusion zones, reaction rims, and resorbed faces of the phenocrysts such as orthopyroxene and plagioclase indicate processes of recrystallization and/or partial dissolution of nonequilibrium crystals in the melt and indicate intratelluric nature of the dyke phenocrysts that cores are inherited from the EC derivatives/cumulate. The mineral thermometry estimates are: (1) the parent magma starting temperatures of 1200–1400 °С and (2) the EC crystallization temperatures 1080–1155 °С, (3) the PD emplacement temperatures 910–1070 °С. The petrogenetic model supposes the generation of EC high-temperature magmas similar to boninites from an upper metasomatized mantle. The melt is contaminated with continental crust lithologies. It implies the half-way evolved magma chamber in the crust. The PD melt, as a result of ending of the half-way magma chamber evolution, was emplaced into the still unheated EC plutons.

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