Petrology of Metavolcanic Rocks in the Bishop Corners – Donaldson Area, Grenville Province, Ontario

1973 ◽  
Vol 10 (5) ◽  
pp. 589-614 ◽  
Author(s):  
K. Sethuraman ◽  
John M. Moore Jr.
Keyword(s):  
Alkali Basalt ◽  
Bulk Composition ◽  
Metamorphic Grade ◽  
Chemical Analyses ◽  
Grenville Province ◽  
Clastic Rocks ◽  
Carbonate Sedimentation ◽  
Metavolcanic Rocks ◽  
Apparent Thickness ◽  
Mineral Assemblages

A calc-alkalic suite, with an apparent thickness of 7 km, varies from alkali basalt and tholeiite composition in the lowest part exposed, through andesite flows and pyroclastic rocks, to rhyodacite pyroclastics at the top. Sixty-two chemical analyses demonstrate a single volcanic cycle. Volcanism was succeeded by carbonate sedimentation and intrusion of granodiorite plutons. After deposition of clastic rocks, the entire succession was deformed and metamorphosed in the amphibolite facies.Isograds divide the metavolcanic rocks into five mineral zones: chlorite, biotite, blue-green hornblende, green hornblende, and diopside. Equivalent zones in the pelites are: chloritoid–staurolite, kyanite–staurolite, and sillimanite–muscovite.Fe in epidote, Ca in plagioclase, K and Na in hornblende, and ferric/ferrous ratio in rocks, biotite, and hornblende all increase in mafic and intermediate rocks, with increasing metamorphic grade. In biotite and hornblende, octahedral Al decreases with grade, whereas other chemical variables are related to bulk composition. Mineral assemblages and hornblende compositions indicate metamorphic conditions between Abukuma and classical Barrovian facies series.

The carbonate-flysch transition (late Maastrichtian-late Palaeocene) in the Arachova sequence of the Parnassus-Ghiona Zone, central Greece

1994 ◽  
Vol 131 (6) ◽  
pp. 819-836 ◽  
Author(s):  
Sophia Gregou ◽  
Nikolaos Solakius ◽  
Fotini Pomoni-Papaioannou
Keyword(s):  
Mineralogical Composition ◽  
Clastic Material ◽  
Amorphous Iron ◽  
Clastic Rocks ◽  
Carbonate Sedimentation ◽  
Marginal Areas ◽  
Mineral Assemblages ◽  
Tectonically Active ◽  
Soil Forming Processes ◽  
Pelagonian Zone

AbstractThe transition from the carbonate to the flysch facies in the Arachova sequence of the Parnassus-Ghiona Zone is represented by argillaceous limestone beds with flaser structures deposited during latest Maastrichtian-Palaeocene time in a pelagic carbonate environment with a periodic clastic influx. Deposition was continuous except for a short interruption during the K/T boundary interval and the earliest Palaeocene when the area was subaerially exposed. This interruption gave rise to the development of a brecciated carbonate horizon through soil-forming processes. The mineralogical composition of the clastic influx (i.e. quartz, feldspars, clay minerals, amorphous iron oxides, amorphous phosphatic compounds), in particular the clay mineral assemblages (i.e. illite, chlorite, irregularly interstratified illite-vermiculite), shows that the clastic supply represents erosional material that originated from a tectonically active continental setting of both carbonate and clastic rocks, presumably the Pelagonian Zone, as for the flysch of the Beotian and Sub-Pelagonian Zones. The arrival of the first clastic material in the Arachova area as early as latest Maastrichtian time, its Pelagonian origin and the persistence of pelagic conditions of sedimentation throughout the Palaeocene, indicate that the Arachova area was situated along the northeastern margin of the Parnassus platform and that it subsided into the Beotian basin. While the central areas of the platform remained tectonically stable during middle Palaeocene times and there was an extensive development of stromatolites, the northeastern marginal areas transitional to the Beotian basin continued to subside allowing pelagic carbonate sedimentation with periods of clastic influx. The total collapse of the platform in the late Palaeocene gave rise to the deposition of the flysch over the entire zone.

The Tremolite Isograd near Marble Lake, Ontario

1973 ◽  
Vol 10 (6) ◽  
pp. 936-947 ◽  
Author(s):  
Ian Hutcheon ◽  
J. M. Moore
Keyword(s):  
Vapor Phase ◽  
Experimental Work ◽  
Lake Ontario ◽  
Amphibolite Facies ◽  
High Angle ◽  
Grenville Province ◽  
Metavolcanic Rocks ◽  
Mineral Assemblages ◽  
Total P

Marble, metavolcanic rocks, and pelite are found in a northeasterly trending belt near Marble Lake, in the Grenville Province, Ontario. The rocks have been metamorphosed to the lower amphibolite facies in the southwest, the grade increasing to the mid-amphibolite facies towards the northeast. Northwest-trending isograds in the metavolcanic rocks are at a high angle to the northeast-trending tremolite isograd in the marbles. Mineral assemblages indicate total pressures between 4 and 5 kbar and temperatures ranging from approximately 350 °C to over 600 °C. Temperatures estimated by calcite–dolomite solvus geothermometry and applied to experimental work in the system CaO–MgO–SiO2–CO2–H2O indicate: (i) P(total) = P(CO2) + P(H2O) was greater than 3 kbars; (ii) temperatures on the tremolite isograd were from approximately 450 to 550 °C and indicate that the tremolite isograd is not isothermal; (iii) the composition of the vapor phase present during metamorphism was approximately X(CO2) = 0.7 – 0.8; (iv) temperatures in the belt were from less than 400 °C in the southwest to more than 600 °C in the northeast.

Geochronology of detrital zircons from the Elzevir and Frontenac terranes, Central Metasedimentary Belt, Grenville Province, Ontario

1993 ◽  
Vol 30 (3) ◽  
pp. 465-473 ◽  
Author(s):  
E. Anne Sager-Kinsman ◽  
R. R. Parrish
Keyword(s):  
Detrital Zircons ◽  
Time Interval ◽  
Adirondack Mountains ◽  
Sedimentary Sequence ◽  
Grenville Province ◽  
Clastic Rocks ◽  
Metavolcanic Rocks ◽  
Group A ◽  
Clastic Sedimentary ◽  
Detrital Zircon Ages

The Central Metasedimentary Belt (CMB) of the Grenville Province contains metasedimentary sequences belonging to a number of distinct tectono-stratigraphic terranes whose depositional ages are poorly known. This study provides information on not only the provenance, but also the maximum age of clastic rocks in two of these terranes, the Elzevir Terrane on the northwest and the Frontenac Terrane to its southeast, adjacent to the Adirondack Mountains of New York.The Flinton Group, a component of the Elzevir Terrane, is a distinctive, mostly clastic, sedimentary sequence that unconformably overlies igneous and metavolcanic rocks of the main part of Elzevir Terrane of the CMB. Analyzed zircons from quartzose metasediments of the Flinton Group are 0–2% discordant and range in age from 1150 to 1335 Ma, with older rounded grains at 1461 ± 5 and 1877 ± 3 Ma. The quartzite was therefore deposited after ca. 1150 Ma, indicating that the Flinton Group is more than 100 Ma younger than the intrusion of the underlying Elzevir batholith. We speculate that 1150–1180 Ma zircons within the Flinton Group were derived from plutons in the Frontenac Terrane to the southeast, implying that the Elzevir and Frontenac terranes were contiguous during Flinton Group deposition. Subsequent metamorphism of the Flinton Group occured between 1150 and 1080 Ma.The high-grade Frontenac Terrane of the CMB lies southeast of Elzevir Terrane, and contains marble associated with pelitic gneiss and quartzite, as well as granitic intrusive rocks; it resembles a metamorphosed continental margin sedimentary sequence. U–Pb analyses of zircons from quartzites from two different localities are generally less than 5% discordant, but show stronger evidence for Grenvillian Pb loss than zircons from the Flinton Group. 207Pb/206Pb ages range from 1493 to 2580 Ma, with one analysis (2% discordant) at 1306 ± 16 Ma, another at 3185 ± 3 Ma, and a cluster of ages between 1745 and 1892 Ma. Detrital zircon ages are, for the most part, distinctly older than in the Flinton Group. The age of this quartzite sequence is tentatively regarded as less than ca. 1300 Ma (based on one grain), but is certainly less than 1500 Ma. It could therefore have been deposited during the same time interval as the 1.2–1.3 Ga metasedimentary and metavolcanic rocks of the Elzevir Terrane. Although Frontenac Terrane experienced metamorphism along with Elzevir Terrane around 1.1 Ga, the principle metamorphic culmination in the Frontenac occurred prior to 1170 Ma.

Geochemistry of the felsic metavolcanic rocks of the Wakeham Group: a metamorphosed peralkaline suite from the eastern Grenville Province, Quebec, Canada

1986 ◽  
Vol 23 (7) ◽  
pp. 978-984 ◽  
Author(s):  
James H. Bourne
Keyword(s):  
Incompatible Trace Element ◽  
White Mica ◽  
Low Grade ◽  
Textural Features ◽  
Chemical Analyses ◽  
Grenville Province ◽  
Metavolcanic Rocks ◽  
Group A ◽  
Grenvillian Orogeny ◽  
Acid Volcanics

The Wakeham Group is a suite of low-grade (greenschist facies) rocks located in the eastern Grenville Province. In order of volumetric importance, it consists of sandstones, acid volcanics, and gabbro dykes and sills. This report deals with the acid volcanic member of the group. Primary textural features have in large part been preserved. The minerals present include stilpnomelane, white mica, albite, titanite, and zircon. Calculations using 33 chemical analyses show that 29 of the compositions have normative corundum. The rocks would therefore appear to be predominantly peraluminous; however, incompatible trace-element data show affinities with other anorogenic, peralkaline suites. It is proposed that alkali loss, probably during the subsequent Grenvillian orogeny, imposed a peraluminous composition on originally peralkaline rocks. The Wakeham Group cannot be definitively correlated with other metavolcanic rocks found in the region.

scholarly journals PHYSICAL-MECHANICAL PROPERTIES OF METAVOLCANIC ROCKS OF THE MOUNTAIN CRIMEA

2018 ◽  
Vol 13 (4-5) ◽  
pp. 36-51
Author(s):  
J. V. Frolova ◽  
V. V. Ladygin ◽  
E. M. Spiridonov ◽  
G. N. Ovsyannikov
Keyword(s):  
Mechanical Properties ◽  
Magnetic Susceptibility ◽  
Volcanic Rocks ◽  
Low Grade ◽  
Secondary Mineral ◽  
Grade Metamorphism ◽  
Clastic Rocks ◽  
Metavolcanic Rocks ◽  
Physical Density ◽  
Characteristic Values

The article considers the petrogenetic features of the volcanogenic rocks of the Middle Jurassic age of the Mountain Crimea and analyzes their influence on physical (density, porosity, water absorption, and magnetic susceptibility) and physical-mechanical properties (strength, modulus of elasticity, and Poisson's ratio). Among volcanogenic strata there are subvolcanic, effusive and volcanogenic-clastic rocks. All volcanic rocks were altered under the influence of the regional low-grade metamorphism of the zeolite and prehnite-pumpellyite facies, which resulted in a greenstone appearance. Among the secondary mineral the most common are albite, chlorite, quartz, adularia, sericite, calcite, pumpellyite, prenite, zeolites, epidote, sphene, and clay minerals. It is shown that low-grade metamorphism is characterized by heterogenious transformations: there are both slightly modified, practically fresh differences, and fully altered rocks. Tuffs are usually altered to a greater extent than effusive and subvolcanic rocks. In general, effusive and volcanogenic-clastic rocks differ markedly in their physicalmechanical properties, which is due to the peculiarities of their formation: the former are substantially more dense and stronger, less porous and compressible. However, these differences are leveled as a result of intensive changes in mineral composition and porosity in the process of low-grade metamorphism. The most characteristic values of metavolcanite properties were revealed. It is shown that among all studied parameters, the magnetic susceptibility most clearly correlates with the degree of rocks alteration.

Peraluminous sapphirine from the Aileron district, Arunta Block, central Australia

1987 ◽  
Vol 51 (361) ◽  
pp. 409-415 ◽  
Author(s):  
R. G. Warren ◽  
B. J. Hensen
Keyword(s):  
Bulk Composition ◽  
Granulite Facies ◽  
The Other ◽  
Stable Phase ◽  
Mineral Assemblages ◽  
Central Australia

AbstractSpecimens collected from a small lens of phlogopite-rich rock in the granulite-facies terrain of the Arunta Block, central Australia, have unusual bulk compositions and mineral assemblages. One sample consists of phlogopite enclosing blue spinel (mg 96) with minute granules of corundum and sapphirine at the margins; a second of phlogopite enclosing porphyroblasts of corundum and peraluminous sapphirine. In the first the sapphirine is close to the 7 : 9 : 3 composition; in the other it is markedly peraluminous, e.g. (Mg1.628Fe0.028)Al4.714Si0.636O10, intermediate between the 7 : 9 : 3 and 3 : 5 : 1 members. The texture suggests that this sapphirine is a stable phase in equilibrium with eastonitic phlogopite and corundum. The very potassic, very magnesian bulk composition of the rocks is attributed to potassium metasomatism of a protolith consisting of magnesian chlorite and quartz.

Octahedral occupancy and the chemical composition of diagenetic (low-temperature) chlorites

Clay Minerals ◽  
1991 ◽  
Vol 26 (2) ◽  
pp. 149-168 ◽  
Author(s):  
S. Hillier ◽  
B. Velde
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Bulk Composition ◽  
Compositional Variation ◽  
Low Grade ◽  
Chemical Analyses ◽  
Method Of Calculation ◽  
Sedimentary Sequences ◽  
Wet Chemical ◽  
Potential Use

AbstractThe chemical composition of about 500 diagenetic chlorites, determined by electron microprobe, has been studied in six different sedimentary sequences spanning conditions from early diagenesis to low-grade metamorphism, in the temperature range 40–330°C. The range of Fe/(Fe + Mg) is almost complete and is positively correlated with Al. Five sequences show the same compositional variation. In each, the most siliceous chlorites have the lowest R2+, substantially more octahedral than tetrahedral Al, and the lowest octahedral totals. Conversely, the least siliceous have the highest R2+, nearly equal octahedral and tetrahedral Al, and octahedral totals close to that for an ideal trioctahedral mineral. A dioctahedral substitution Si[]R2−2 (where [] represents a vacant octahedral site) which decreases with temperature, describes this variation. Low octahedral totals are, however, induced by the method of calculation and need not indicate vacancies; for published wet chemical analyses of metamorphic chlorites they may simply indicate oxidation of Fe. Intergrown dioctahedral phyllosilicates may partly account for apparent vacancies in diagenetic chlorites. Nevertheless, the correlation of composition with temperature and similarities to the temperature-related evolution of synthetic chlorites, suggest that diagenetic chlorites are compositionally distinct from, but metastable with respect to, fully trioctahedral metamorphic chlorites. Temperature-related trends are modified by bulk composition, complicating their potential use for low-temperature geothermometry.

Forsterite chondrites; the meteorites Kakangari, Mount Morris (Wisconsin), Pontlyfni, and Winona

1977 ◽  
Vol 41 (318) ◽  
pp. 201-210 ◽  
Author(s):  
A. L. Graham ◽  
A. J. Easton ◽  
R. Hutchison
Keyword(s):  
Natural History ◽  
Bulk Composition ◽  
British Museum ◽  
Mineral Chemistry ◽  
Chemical Analyses ◽  
Ordinary Chondrites ◽  
Sulphide Minerals ◽  
Bulk Chemical ◽  
Original Owner ◽  
Cursory Examination

SummaryPontlyfni and Mount Morris (Wisconsin) are briefly described. Chondrule structure is absent from both, the latter is coarsely crystalline and both are sulphide-rich and contain forsterite and enstatite. Kakangari has well-defined chondrules; its silicate and sulphide minerals are unequilibrated, but similar to those of Pont-lyfni and Mount Morris (Wisconsin). New bulk chemical analyses are presented; Pontlyfni has 33·84 % total Fe and 7·04 % S; Mount Morris (Wisconsin) has 19·88 % total Fe and 4·72 % S; and Kakangari has 22·79 % total Fe and 5·30 % S. These three meteorites, together with Winona, have ordinary chondritic Mg/Si ratios, which result in their having abundant forsterite; this distinguishes them from E-chondrites. The four meteorites have Mg/Si ratios lower than those of C-chondrites, and they are more reduced than C or ordinary chondrites. These four unusual stones, therefore, have some chemical similarities, for example all have Mg/Si (atomic) of about 0·95, mean olivine composition ranging from Fa1 to Fa5, and significant Cr in the sulphide. Cumberland Fails chondritic xenoliths and other exotic fragments in polymict meteorites may be related to the four stones, which may ultimately prove to belong to a distinct chemical group of chondrites related to the irons of Group IAB.These meteorites are described and discussed together because they have similarities in mineralogy, bulk composition, and oxidation state. All have more than 10 % forsterite (i.e. an olivine in the range Fa0·10). In our study we investigated the mineral chemistry of, first, Kakangari (Graham and Hutchison, 1974), and then Mount Morris (Wisconsin), with cursory examination of the previously described Winona (Mason and Jarosewich, 1967) and Cumberland Falls chondritic fraction (Binns, 1969; Jarosewich, 1967). By chance, the British Museum (Natural History) acquired the Pontlyfni stone during the course of this work. Pontlyfni fell in Wales in 1931, but is so far undescribed; it proved to be chemically and mineralogically similar to Kakangari. We thank Mr. J. R. Owen, the original owner, for its timely addition to the Museum's Collection.

Nature of the Quetico–Wabigoon boundary in the de Courcey – Smiley Lakes area, northwestern Ontario

1976 ◽  
Vol 13 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Manfred M. Kehlenbeck
Keyword(s):  
Regional Metamorphism ◽  
Sedimentary Rocks ◽  
Metamorphic Grade ◽  
Boundary Zone ◽  
Present Level ◽  
Metasedimentary Rocks ◽  
The North ◽  
Northwestern Ontario ◽  
Multiple Phase ◽  
Mineral Assemblages

In the de Courcey – Smiley Lakes Area, the boundary between the Quetico and Wabigoon Belts is expressed by a sequence of pelitic to semi-pelitic schists and gneisses. At the present level of erosion, these metasedimentary rocks are in contact with granodioritic gneisses, granites, and pegmatites, which are exposed to the south.To the north of this area, regional metamorphism of volcanic and sedimentary rocks has resulted in greenschist facies assemblages, which characterize the Wabigoon Belt in general. In the boundary zone, the metamorphic grade increases southward toward de Courcey and Smiley Lakes.Formation of three distinct foliation surfaces was accompanied by syn-tectonic as well as post-tectonic recrystallization, producing polymetamorphic schists.In the boundary zone, mineral assemblages comprising andalusile, sillimanite, cordierite, garnet. biotite, and muscovite form a facies series of the Abukuma type.The boundary between the Quetico and Wabigoon Belts in this area is a complex zone in which rocks of both belts have been reconstituted by multiple-phase metamorphism and partial melting.

Isograds and mineral assemblages in the eastern axial zone, Montagne Noire (France): implications for temperature gradients and P–T history

1982 ◽  
Vol 19 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Peter H. Thompson ◽  
Jean-Pierre Bard
Keyword(s):  
Metamorphic Grade ◽  
Temperature Gradients ◽  
Low Grade ◽  
Reaction Sequence ◽  
Axial Zone ◽  
Rock Composition ◽  
Mineral Assemblages ◽  
Montagne Noire ◽  
Sequence Study

Detailed petrography across a metapelitic sequence in the eastern axial zone of the Montagne Noire, France, is the basis for a sequence of isograds marking the first appearance of biotite–cordierite, staurolite, andalusite, and sillimanite. The juxtaposition of low-grade biotite-free rocks against medium-grade rocks at the gently dipping biotite–cordierite isograd is attributed to tectonic telescoping of the metamorphic sequence. Study of mineral assemblages with respect to an AFM reaction sequence indicates the staurolite isograd is related to changes in rock composition, and complex assemblages in the sillimanite zone may be the result of unstable persistence of minerals formed when metamorphic grade was lower. These assemblages are interpreted to contain a record of part of the P–T history during which pressure decreased as temperature increased. P–T profiles show that temperature gradients of 200–300 °C/km suggested by previous workers are not required to explain the isograd pattern; gradients of 37 °C/km or less are sufficient.

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