The Petrology of Late Tertiary Dolerite Plugs in the South Cariboo Region, British Columbia

1973 ◽  
Vol 10 (2) ◽  
pp. 205-225 ◽  
Author(s):  
R. B. Farquharson
Keyword(s):  
British Columbia ◽  
Trace Element ◽  
Chemical Nature ◽  
Major Element ◽  
Basaltic Magma ◽  
Olivine Basalt ◽  
Coarse Grained ◽  
Basalt Magma ◽  
Late Tertiary ◽  
High Level

The petrology of four plugs of fresh, coarse-grained olivine dolerite, of Pliocene age, is described in this paper. Two plugs, which exhibit textural and mineralogical variations, are described in detail. Major element analyses and selected trace element analyses for fifteen samples illustrate the chemical nature of the dolerite as well as fractionation in small marginal portions of the plugs. Strontium isotope values indicate that the plugs represent basaltic magma that was not contaminated by crastal matter. Both the mineralogy and the chemistry of the plugs indicate that the magma was mildly alkaline, and suggest that it was a differentiate of a primary olivine basalt magma, perhaps derived through crystal fractionation in a high-level magma chamber.

A new locality for primary xenolith-bearing nephelinites in northwestern British Columbia

1985 ◽  
Vol 22 (10) ◽  
pp. 1556-1559 ◽  
Author(s):  
Michael D. Higgins ◽  
John M. Allen
Keyword(s):  
British Columbia ◽  
Trace Element ◽  
Volcanic Belt ◽  
Primary Magma ◽  
Similar Composition ◽  
Element Abundances ◽  
Late Tertiary

High Ni abundances (420–500 ppm) and Mg* values (100 × Mg/(Mg + Fe2+) = 69–71) and the presence of mantle-derived xenoliths indicate that a subvolcanic nephelinite intrusion in northwestern British Columbia represents an unmodified primary magma. A separate, closely associated nephelinite intrusion shows evidence of minor olivine fractionation from a similar composition. Only three other occurrences of primary nephelinite have been described. This new occurrence suggests that these magmas may not be so rare as previously supposed. The trace-element abundances closely resemble those of primary nephelinites of similar La content from Freemans Cove, Canada. Such compositions are usually taken as evidence of intraplate rifting and doming. Therefore, these rocks are further evidence of late Tertiary or Quaternary rifting in the Stikine volcanic belt.

Petrographic constraints on modelling the crystallization of basalt magma, Cow Lakes, southeast Oregon

1988 ◽  
Vol 25 (4) ◽  
pp. 486-494
Author(s):  
J. K. Russell ◽  
G. T. Nixon ◽  
T. H. Pearce
Keyword(s):  
Basaltic Magma ◽  
Olivine Basalt ◽  
Significant Proportion ◽  
Thermodynamic Modelling ◽  
Interference Microscopy ◽  
Basalt Magma ◽  
Laser Interference ◽  
Chemical Zoning ◽  
Laser Interference Microscopy ◽  
Crystallization Path

Thermodynamic calculations and models of olivine zoning profiles are used to estimate the crystallization history of a basaltic magma from Cow Lakes, southeast Oregon. The lava is an alkali olivine basalt containing olivine and plagioclase phenocrysts and microphenocrysts. The geometry and range of chemical zoning in the olivine phenocrysts have been delineated by laser interference microscopy and electron microprobe analysis. The olivine phenocrysts are characterized by homogeneous cores and rims that exhibit strong, continuous, normal zoning (ΔFo = 7–19 mol%).Thermodynamic modelling has been used to estimate the magmatic crystallization path of the Cow Lakes basalt on the basis of the phenocryst assemblage and mineral compositions. The calculated crystallization path begins at 1290 °C and 0.5 GPa ([Formula: see text]) with equilibrium crystallization of the olivine to 1265 °C. Plagioclase appears at 1225 °C, followed by clinopyroxene at 1205 °C. Intratelluric crystallization was terminated prior to crystallization of the clinopyroxene, which is seen in the groundmass but not as phenocrysts.The thermodynamic modelling provides a means to numerically simulate the zoning patterns in olivine defined by the laser interference microscopy. Simulated and observed zoning patterns both have compositionally flat cores and strongly zoned rims. The extent of zoning observed in the olivine phenocrysts is, however, approximately twice the predicted extent, and it appears that a significant proportion of olivine phenocrysts crystallized during ascent or upon eruption.

Episodic tourmaline growth and re-equilibration in mica pegmatite from the Bihar Mica Belt, India: major- and trace-element variations under pegmatitic and hydrothermal conditions

2016 ◽  
Vol 154 (1) ◽  
pp. 68-86 ◽  
Author(s):  
PRANJIT HAZARIKA ◽  
DEWASHISH UPADHYAY ◽  
KAMAL LOCHAN PRUSETH
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Major Element ◽  
Element Composition ◽  
Coarse Grained ◽  
Partial Replacement ◽  
Type I ◽  
Type Ii ◽  
Hydrothermal Conditions ◽  
Major Element Composition

AbstractMica pegmatites from the Bihar Mica Belt contain three distinct generations of tourmaline. The major-element composition, substitution vectors and trajectories within each group are different, which indicates that the three types of tourmalines are not a part of one evolutionary series. Rather, the differences in their chemistries as well their mutual microtextural relations, can be best explained by growth of tourmaline from pegmatitic melts followed by episodic re-equilibration during discrete geological events. The euhedral, coarse-grained brown type I tourmaline cores have relatively high Ca, Mg (XMgc. 0.37) and Al with correlated variation in Sr, Sc, Ti, Zr, Y, Cr, Pb and Rare Earth elements (REEs). They are inferred to have crystallized from pegmatitic melts. Monazites included within these tourmalines give chemical ages of 1290−1242 Ma interpreted to date the crystallization of the pegmatitic tourmaline. The bluish type II and greyish type III tourmalines with low Ca and Mg contents (XMg = 0.16−0.27) and high Zn, Sn, Nb, Ta and Na, formed by pseudomorphic partial replacement of the pegmatitic tourmaline via fluid-mediated coupled dissolution–reprecipitation, are ascribed to a hydrothermal origin. The ages obtained from monazites included in these tourmalines indicate two alteration events at c. 1100 Ma and c. 950 Ma. The correlated variation of Ca, Mg and Fe and the trace elements Sr, Sn, Sc, Zn and REE within the tourmalines indicates that the trace-element concentrations of tourmaline are controlled not only by the fluid chemistry but also by coupled substitutions with major-element ions.

Fluid activity in the lower crust and upper mantle: mineralogical evidence bearing on the origin of amphibole and scapolite in ultramafic and mafic granulite xenoliths

1987 ◽  
Vol 51 (363) ◽  
pp. 719-732 ◽  
Author(s):  
A. J. Stolz
Keyword(s):  
Basaltic Magma ◽  
Olivine Basalt ◽  
Basalt Magma ◽  
Crust And Upper Mantle ◽  
Ultramafic Xenoliths ◽  
Basaltic Magmas ◽  
Alkali Olivine Basalt ◽  
Textural Evidence ◽  
Granulite Xenoliths ◽  
Mineralogical Evidence

AbstractXenoliths in an olivine nephelinite from the McBride Province, North Queensland, include Cr-diopside lherzolites, spinel and garnet websterites, felsic, 2-pyroxene and garnet granulites, and hornblendites. The spinel and garnet websterites are interpreted as crystal segregations from olivine basalt or alkali olivine basalt magma at ∼ 12 kbar followed by isobaric cooling (to approximately 900–1000°C) and subsolidus reequilibration. Garnet and 2-pyroxene granulites are mineralogically and texturally distinct and are considered to represent relatively large degrees of crystallization of basaltic magmas at comparable or slightly lower pressures (8–12 kbar). Mafic and ultramafic xenoliths have been modified to varying degrees following the relatively recent influx of a H2O- and CO2-bearing fluid. Variable amounts of amphibole and mica developed in response to the introduced fluid and it is argued that some hornblendites are the end-products of this process acting on spinel websterites. Felsic and 2-pyroxene granulite xenoliths display only minor evidence of increased PH2O. Mineralogical and textural evidence indicates high-sulphur Ca-rich scapolite in several garnet granulites did not form in response to the increased fluid activities. It is proposed the scapolite was a primary cumulate phase precipitated from alkali basaltic magma under elevated fo2 and fso2 conditions.

The Cheslatta Lake suite: Miocene mafic, alkaline magmatism in central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 697-717 ◽  
Author(s):  
Robert G Anderson ◽  
Jonah Resnick ◽  
James K Russell ◽  
G J Woodsworth ◽  
Michael E Villeneuve ◽  
...  
Keyword(s):  
British Columbia ◽  
Olivine Basalt ◽  
Volcanic Belt ◽  
Primitive Mantle ◽  
Alkaline Magmatism ◽  
Type Area ◽  
Late Tertiary ◽  
Alkali Olivine Basalt ◽  
Trace Element Contents ◽  
Geochemical Studies

New mapping, mineralogical, and geochemical studies help characterize late Tertiary primitive, alkaline, sodic basanite, alkali olivine basalt, transitional basalt, and diabase in the Nechako River, Whitesail Lake, and McLeod Lake map areas of central British Columbia and distinguish the Miocene Cheslatta Lake suite. The suite encompasses scattered erosional remnants of topographically distinct, columnar-jointed, olivine-phyric basalt and diabase volcanic necks, dykes, and associated lava flows north of the Anahim volcanic belt and west of the Pinchi Fault. Volcanic centres at Alasla Mountain and at Cutoff Creek, near Cheslatta Lake, are proposed as type areas. Olivine, plagioclase, and pyroxene phenocrysts, megacrysts, and (or) xenocrysts; common ultramafic xenoliths; and rare but significant plutonic and metamorphic xenoliths are characteristic. Basanite, transitional basalt, and alkali olivine basalt groundmass contain plagioclase, clinopyroxene, Fe-Ti oxides, feldspathoid, olivine, and apatite. The Cheslatta Lake suite is characterized by its alkaline character, olivine-rich (>10 wt.%) normative mineralogy, and silica-undersaturated nature (>1 wt.% normative nepheline; hypersthene-normative rocks are uncommon). Mg numbers vary between 72–42. Some samples encompass near-primitive mantle melt compositions. Cheslatta Lake suite rocks in the Nechako River area are distinguished from the underlying Eocene Endako and stratigraphically higher Neogene Chilcotin groups basaltic andesite lavas within the study area, and from the Chilcotin Group basalt in the type area south of the Anahim volcanic belt, by form, preserved thickness, phenocryst–xenocryst mineralogy, amygdule abundance, included xenoliths, isotopic age, and major and incompatible, high field strength, and rare-earth trace element contents.

Late Cenozoic volcanic rocks of the Clearwater – Wells Gray area, British Columbia

1984 ◽  
Vol 21 (3) ◽  
pp. 267-277 ◽  
Author(s):  
Catherine J. Hickson ◽  
J. G. Souther
Keyword(s):  
British Columbia ◽  
Volcanic Activity ◽  
Olivine Basalt ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Pillow Lava ◽  
Late Cenozoic ◽  
Gray Area ◽  
High Level ◽  
Tuff Breccia

The Clearwater – Wells Gray area of east-central British Columbia includes a succession of late Cenozoic, alkali olivine basalt flows that lie east of the extensive Chilcotin lavas and define the eastern end of the Anahim Volcanic Belt. The rocks are petrographically similar to but less altered than the Chilcotin basalts. The volcanic activity spanned at least two episodes of glacial advance and produced both subaerial flows and a subaqueous facies comprising pillow lava, pillow breccia, and tuff breccia, locally intercalated with fluvial gravels and sand. Four morphological assemblages have been recognized. An early glacial assemblage, characterized by tuyalike forms, gives K – Ar dates of 0.27 – 3.5 Ma. These circular features are surrounded by a deeply dissected valley-filling assemblage of subaerial and minor subaqueous flows and tuff breccia that rest locally on lag gravel and till. Subaerial flows in this assemblage give K – Ar dates of 0.15 – 0.56 Ma. Whitehorse Bluffs, a volcanic centre composed of crudely laminated tuff cut by high-level dykes, may be a source of some of these valley-filling flows. A late interglacial assemblage is composed of subaerial pyroclastic material, transitional deposits, and deposits that are clearly subaqueous. Volcanic activity in the area culminated with the formation of pyroclastic cones, blocky lava flows, and pit craters that postdate the last Cordilleran glaciation.

Petrology of Alkaline Rocks from Cuttingsville and the Shelburne Peninsula; Vermont

1973 ◽  
Vol 10 (8) ◽  
pp. 1244-1256 ◽  
Author(s):  
R. Laurent ◽  
T. C. Pierson
Keyword(s):  
Olivine Basalt ◽  
Coarse Grained ◽  
Basalt Magma ◽  
Uppermost Mantle ◽  
Alkaline Granite ◽  
Quartz Syenite ◽  
Thermal Plumes ◽  
Alkaline Rocks ◽  
Fine Grained ◽  
Sedimentary Sequences

The Cuttingsville composite stock has feldspathoid-bearing and quartz–bearing alkaline rocks emplaced in Precambrian schists of the Green Mountains. The main intrusions are, from oldest to youngest: (1) hastingsite foyaite and biotite foyaite, (2) diorite, (3) essexite, porphyritic essexite, plagifoyaite, and sodalite foyaite, (4) alkaline quartz syenite, (5) dikes of tephritic phonolite porphyry, phonolite porphyry, and microplagifoyaite. The K–Ar ages of 100 m.y. on the hastingsite foyaite and of 96.4 m.y. on the essexite indicate that this intrusion is perhaps the youngest manifestation of magmatic activity in New England.In the Shelburne peninsula, the alkaline rocks are intrusive into the Paleozoic sedimentary sequences of the Champlain Valley; they crop out on opposite sides of Lake Champlain. Intrusions consist of small stocks of alkaline syenite grading from a coarse-grained core to a fine-grained quartzose margin, which is cut by dikes of alkaline granite aplite, and of sills of trachyte porphyry. The alkaline rocks of the Shelburne peninsula are analogous to the alkaline syenites of unit 4 in Cuttingsville.We conclude that the rocks described did not originate through differentiation of an alkaline olivine basalt magma. Instead, partial and progressive melting of gabbroic phases in the uppermost mantle is proposed to account for the chemical relationships suggesting a source within the mantle. The absence of large amounts of mafic rocks, the order of emplacement which does not correlate with fractionation trends, and the presence of two syenitic melts of contrasted composition are evidences to support the proposal. Partial melting could have been caused by passage of the lithosphere over thermal "plumes" in the lower mantle.

Petrology of syenites from center III of the Coldwell alkaline complex, northwestern Ontario, Canada

1993 ◽  
Vol 30 (1) ◽  
pp. 145-158 ◽  
Author(s):  
Roger H. Mitchell ◽  
R. Garth Platt ◽  
Jurate Lukosius-Sanders ◽  
Maureen Artist-Downey ◽  
Shelley Moogk-Pickard
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Major Element ◽  
Volcanic Rocks ◽  
Basalt Magma ◽  
Alkaline Complex ◽  
Quartz Syenite ◽  
Element Abundances ◽  
Northwestern Ontario ◽  
Single Batch

Center III of the Coldwell alkaline complex consists of metaluminous hypersolvus syenites, which in order of intrusion are magnesiohornblende syenite, contaminated ferro-edenite syenite, ferroedenite syenite, and quartz syenite. Contaminated syenites were formed by the assimilation of coeval basaltic volcanic rocks. The suite as a whole is characterized by the presence of a wide variety of amphiboles ranging in composition from magnesiohornblende through ferroedenite and ferrorichterite to arfvedsonite. Pyroxenes are rare and hedenbergite is present in significant amounts only in quartz syenite. Whole-rock major element data indicate that the majority of the syenites do not represent liquid compositions. The syenites have high contents of Nb, Zr, Th, U, Y, and Ga and have the geochemical character of A-type granitoids. Rare earth and other trace element abundances suggest that the quartz syenites cannot be differentiates of the magma that formed the ferroedenite syenites. All syenites are considered to have originated by the extensive fractional crystallization of mantle-derived basalt magma within the plutonic infrastructure of the complex. The syenite suite does not represent the differentiation products of a single batch of magma. Multiple intrusion, contamination, and brecciation of preexisting syenite plutons have resulted in the complex geological relationships characteristic of center III.

The occurrence of Zr-bearing amphiboles and their relationships with the pyroxenes and biotites in the teschenite and nepheline syenites of a differentiated dolerite boss, Islay, NW Scotland

2000 ◽  
Vol 64 (3) ◽  
pp. 459-468 ◽  
Author(s):  
R. J. Preston ◽  
M. J. Hole ◽  
J. Still
Keyword(s):  
Trace Element ◽  
Late Stage ◽  
Nepheline Syenite ◽  
Olivine Basalt ◽  
Local Environment ◽  
Basalt Magma ◽  
Single Body ◽  
Small Scales ◽  
Alkali Olivine Basalt

AbstractThe Cnoc Rhaonastil minor dolerite intrusion on Islay, NW Scotland represents a single body of alkali olivine basalt magma which differentiated in situ, from leucodolerite, through teschenite to minor nepheline syenite. The syenites occur as isolated nests and pegmatitic schlieren within the leucodolerite, and schlieren of gabbroic pegmatite also occur at the margin of the teschenite. The differentiated rocks contain pyroxene, amphibole and biotite of variable compositions which reflect both primary fractionation processes and late-stage deuteric alteration and reaction.Mafic phases within the gabbroic pegmatite, teschenite and syenite are typically rimmed and speckled with biotite, the composition of which is controlled by the local environment of crystallization. The nepheline syenites contain primary ferro-kaersutite which, where in contact with interstitial patches, has been altered to arfvedsonite, which occasionally contains up to 1.2 wt.% ZrO2. The occurrence of Zr-arfvedsonite (and of Zr-aegirine) in interstitial patches suggests that variably trace element-enriched domains existed within the residual melts on very small scales.

scholarly journals TIPE GRANIT SEPANJANG PANTAI TIMUR PULAU BATAM DAN PANTAI BARAT PULAU BINTAN, PERAIRAN SELAT BATAM BINTAN

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Deny Setiady ◽  
Faturachman Faturachman
Keyword(s):  
Trace Element ◽  
Major Element ◽  
Peninsular Malaysia ◽  
Coarse Grained ◽  
Eastern Coast ◽  
Coarse Grain ◽  
Eastern Province ◽  
Pink Colour ◽  
Type Granite ◽  
Riau Archipelago

Granit tipe I dan Tipe S tersebar sepanjang Kepulauan Riau. Di Pulau Batam dan Pulau Bintan, yang menerus dari jalur granit Johor Penensular, Malaysia. Granit-granit tersebut menerus secara alamiah dari Provinsi granit Johor sebelah Timur menerus ke kepulauan Riau sampai Bangka Belitung. Ciri granit tipe I berwarna pink biotit hadir berwarna colat gelap, mempunyai komposisi kimia SiO2 antara 53% -76%, kandungan CaO Na2O yang tinggi, kandungan Sr tinggi dan Rb rendah. Ciri granit tipe S biasanya berwarna abu-abu, hornblenda jarang ditemukan, komposisi kimia SiO2 berkisar antara 66% - 76%, mempunyai kandungan CaO dan Na2O yang rendah, biasanya Sr rendah dan Rb tinggi. (Chappel dan white, 1983) Berdasarkan Analisa data megaskopis granit di pantai Pulau Batam sebelah utara (PBT-14) dan PBT-12, berwarna abu-abu dengan tekstur afanitik, mengandung orthoklase (45%), Quartz (20), Biotite (15), Hornblende (5%) dan Plagioclase (10%). sedangkan di tengah -tengah (PBT-13) berwarna kemerahan, ukuran butir menengah sampai kasar,mengandung Orthoklase, kuarsa, Plagioklas hal ini menunjukkan bahwa terdapat perbedaan tipe granit di Pulau Batam yaitu tipe I dan Tipe S. Sedangkan di Pulau Bintan sama dengan PBT-13 yaitu kemerahan, tekstur fanerik yaitu ciri dari tipe I. Berdasarkan analisa petrografis sampel di 3 lokasi di Pulau Batam terdiri dari plagioklas, orthoklas, kuarsa, biotit dan mineral opak. Demikian juga di Pulau Bintan tidak ditemukan hornblenda, kemungkinan tipe S Hal ini menunjukkan bahwa granit di daerah selidikan mempunyai tipe S, karena hornblenda tidak ditemukan. Kandungan senyawa SiO2 yang tinggi di P. Bintan (> 63,55%), kandungan CaO (< 0,99%), dan Na2O (< 3,02%) yang rendah, Serta unsur tanah jarang Sr (>4 ppm), yang tinggi, maka disimpulkan bahwa tipe granit di daerah Bintan adalah Tipe S. Di P. Batam Kandungan SiO2 yang tinggi ( > 71,39%), Kandungan CaO (0,14%- 3,48%), dan Na2O (< 3,33%) yang rendah, Serta unsur tanah jarang Sr (> 17 ppm), yang tinggi, maka tipe granit di daerah Bintan adalah Tipe S. Granites S and I Type are distributed throughout the archipelago, which lie immediately to the south of Johorein Peninsular Malaysia. These granites seem to form a natural continuation of the eastern province granites in Johor to Riau Archipelago until Bangka and Belitung Island. I Type Granite show pink colour in megascopis speciment, SiO2 composition between 53% - 76%, high content Cao and Na2O, higih content Sr and low content Rb. S type granite shows greeyish, no present hornblende, SiO2 composition between 53% - 76%, Low content CaO and Na2O, Granite in the eastern coast of Batam Island in (PBT-14 and PBT-12) are greeyish, afanitic texture is made up of an orthoclase, Quartz, Biotite, Hornblende and Plagioclase. While granite in the middle (PBT-13), reddish, medium to coarse grained, Orthoclase, quartz, Plagioclase. This description shows that granite in Batam is I type and S type, while in Bintan Island is I Type. Base on petrography's analysis in 3 location in Batam island Granite, greeyish, faneric texture, medium - coarse grained, holocrystalyne, hipidiomorfic - allotriomorfic. Orthoclase, quartz, Plagioclase, Biotite, Opaque Mineral. While granite in Bintan island are gray, faneric texture medium to coarse grain, holocristalyn - alotriomorfic, consists of Plagioclase, Orthoclase, quartz and Biotite. These analysis shows that Granit in Batam and Bintan island are S Type because hornblende is not found. Base on Chemist Analysis Major element in Bintan island consists of high content SiO2 (> 63,55), and CaO (< 0,99%), Na2O (< 3,02%) are low Content. Trace element is high content Strontium (>4 PPM ). These analysis shows that granite in Bintan island are S Type. Major element in Bintan island consists of high content SiO2 (>71,39%), and CaO (<0,14%), Na2O (<0,18% ) are low Content. Trace element is high content Strontium (> 17 PPM ). These analysis shows that granite in Bintan island are S Type.

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