Department of Earth Sciences (Fredericton)

Pages


A microstructural study of Penrhyn Slate, of North Wales
A microstructural study of Penrhyn Slate, of North Wales
by James Leonard Davidson, Optical microscopy of three orthogonal ultrathin petrographic sections, 5 to 10 μm, in conjunction with scanning electron microscopy (SEM ) were used in a microstructural analysis of the Penrhyn slates of North Wales. The cleavage domains of these slates are found to be more penetrative than the lenticular domains. Aspect ratios of quartz measured in the X-Z and Y-Z sections are found to be 2.5 and 1.8 respectively. A possible quartz c-axis fabric is observed. Assuming the fabric is not an artifact of measuring it represents extension in the Y direction which is characteristic of doubly plunging folds. Micas of the chlorite mica stacks which have formed kink band boundaries between the portion in the stack and the portion in the cleavage will recrystallize forming two discrete micas. Chlorite has grown in extension sites produced in the splitting of micas in the chlorite-mica stacks. Serrated kink band boundaries are developed in the chlorite of some chlorite stacks. Fluid-enhanced intergranular diffusional mechanisms are most likely responsible for the intimate intergrowths of quartz and mica. Quartz mica intergrowths, mica beards, are developed in a direction grossly parallel to the X axis of the finite strain ellipsoid. The aspect ratios of quartz and the symmetry of the mica beards indicate the orthorhombic symmetry of the finite strain ellipsoid., University of New Brunswick. Department of Geology.

The Zealand Station beryl (aquamarine) deposit, West-Central NB: mineralogic, geochronologic, and petrogenetic constraints
The Zealand Station beryl (aquamarine) deposit, West-Central NB: mineralogic, geochronologic, and petrogenetic constraints
by Kristy-Lee Beal, The Zealand Station deposit is located 30 km northwest of Fredericton, NB, along the north eastern cusp of the Hawkshaw Granite, previously dated at 411 ± 1 Ma by U-Pb titanite. A late-stage, SE-trending, sparsely porphyritic aplite dyke with coarse-grained perthitic feldspar has locally abundant beryl (aquamarine) in the aplitic groundmass. A pegmatitic phase of the dyke crops out 50 m east of the map area; it predominately consists of quartz and K-feldspar, with granophyric texture, and minor wolframite. Beryl is also found near altered greisen pockets and along quartz-rich veins in the granitic host rock; the veins show two predominant orientations: 135°/90° and 010°/75°W. The aplitic dyke has been dated at 400.5 ± 1.2 Ma using U-Pb TIMS on magmatic zircon. This isconsistent with the 404 ± 8 Ma using the U-Th-Pb CHIME method on magmatic monazite using the EPMA technique: these ages link the aplitic dyke to the Allandale Granite that was previously dated at 402 ± 1 Ma by U-Pb (monazite); it is the youngest and most evolved phase of the Devonian Pokiok Batholith. In addition, two monazite analyses yielded an age of 510 ± 20 Ma using EPMA, indicating a supracrustal xenocrystic origin for some of the monazite. The veins and greisen pockets have up to 5.61 wt. % BeO, and up to 20 vol. % beryl in a part of the aplitic phase of the dyke. Beryl samples (n=15) were analysed by EPMA. The average H20 content of the Zealand Station beryl is 1.53 wt. % calculated by (Na20 + 1.4829)/1 .1771 and includes ferric iron (up to 1.44 wt. %), which is the dominant chromophore. The dyke samples have a granitic composition and are predominantly magnesian, slightly potassic, and calc-alkaline with strong peraluminousity (1 .23-4.76). The apliteII pegmatite dykes are highly fractionated, based on their characteristic high incompatible elemental abundances, such as Th (1 l-33ppm), Rb (218-327 ppm), Cs (6-22 ppm), and Ta (3-14 ppm) and elevated HREE (Y, Yb, and Lu); they also have very low Nb/Ta (2.6-7.1) and very high Rb/Sr (4.1-15.8) ratios. The dykes were derived from a probably igneous in origin and had characteristics typical of an A-type source, the age and geological setting of this granite indicate that it is syn- to post- collisional with the Acadian Orogen. As this magma rises there seems to have been increased contamination by metasediments of the recently thickened crust, possibly explaining some of the S-type petrogeochemical characteristics. The dykes are related to the Allandale Granite phase of the Pokiok Batholith by their age, petrology, geochemistry and Nd/Sm isotope ratios (ε-Nd of -2.15 for the dykes whereas the Allandale has a value of -1.6). The pegmatite and aplite are a high-level rare-earth element pegmatite with both NYF and LCT-type characteristics. The beryl geothermobarometer indicated that the dyke crystallized between 600° to 660°C and atapproximately 2.5 kbar., University of New Brunswick. Department of Geology.
1988 Queen Charlotte Basin Experiment: Seismic refraction and gravity models of line 3
1988 Queen Charlotte Basin Experiment: Seismic refraction and gravity models of line 3
by Denise Thérèse Long, The Queen Charlotte Basin is situated off Canada's west coast. It lies between the mainland, a large plate-boundary transform fault, a triple-junction and a subduction zone. In 1988, a large seismic refraction and wide-angle reflection survey was carried out in order to study the basin's structure and evolution. Line 3 of that survey is the focus of this thesis. The velocity model of line 3 was obtained using refraction data from three land-based receivers. The initial sediment thickness and velocity was determined by the reflection section of line 3 and Harlequin Well data. Results show that the upper crust velocities increase from 5.5 km/s to 6.3 km/s at 8 km. Velocities increase in the mid crust from 6.5km/s to 6.7 km/s at 18 km depth. In the lower crust, a velocity of 6.8-6.9 km/s was found with Moho depths ranging from 26-28 km. These velocities correspond well with the results found in the southern sound, and the depth of the Moho is similar to that found in the Hecate Strait. The present Moho depth of line 3 shows that the northern Queen Charlotte Sound is only 80% of the original crustal thickness, strongly indicating an extensional history in the area. The gravity model defined a transition from oceanic to continental crust over a horizontal distance of 75 km (+/- I 0 km) corresponding with a Moho dip of 14 degrees., University of New Brunswick. Department of Geology.
A case history of the discovery and geophysical and geochemical signatures of the Burnt Pond sulphide prospect Noel Paul's Brook Area Central Newfoundland
NTS 12 A/9
A case history of the discovery and geophysical and geochemical signatures of the Burnt Pond sulphide prospect Noel Paul's Brook Area Central Newfoundland NTS 12 A/9
by Peter M. Dimmell, The Burnt Pond prospect is one of six known sulphide deposits in the Victoria Lake Group of the Central Mobile Belt of Newfoundland, the others being the Tally Pond (Boundary) deposit, the Tulks Hill and Tulks East deposits, the Victoria Mine and the Jacks Pond deposit. The Burnt Pond prospect was discovered in 1974 by Noranda Exploration Company, Limited during follow - up of a stream sediment geochemical anomaly in a small brook flowing into the southeast side of Burnt Pond. The subeconomic sulphide mineralization consists of disseminated and fracture filling pyrite, sphalerite, galena and chalcopyrite hosted by the upper part of a pyroclastic felsic volcanic unit, and thin banded massive sulphides near the contact between the overlying sedimentary sequence and the felsic volcanics. This mineralization is thought to be associated with hydrothermal activity during the waning stages of island arc volcanism. Pervasive quartz-chlorite – talc alteration and sericitization accompanies the mineralization. The deposit has no discrete geophysical expression. The contact with the sedimentary units which overlie it is marked by a narrow graphitic shale unit which can be mapped geophysically by airborne and ground electromagnetic methods. Copper, lead, zinc and silver in soils show a strong anomalous zone over the mineralized area. The discovery of this deposit and the recognition of the thick volcanic sequence hosting it led to further work along strike in the Tally Pond area, 15 km to the southwest, which culminated in the discovery of the Tally Pond (Boundary) deposit in 1981., University of New Brunswick. Department of Geology.
A magnetic susceptibility investigation of the Manicouagan impact structure
A magnetic susceptibility investigation of the Manicouagan impact structure
by Randy G. Hopkins, The study of terrestrial impact craters provides significant insight as to how hypervelocity asteroid collisions have affected the Earth and other planetary bodies over geologic time. There is still much to learn about the redistribution of material and readjustment of the Earth's crust following an impact event. This study was performed to gain insight of the distribution of magnetic mineral phases within the melt sheet rock as well as study the melt sheet-basement rock interface at the Manicouagan impact structure in northern Quebec. The magnetic susceptibility of two drill cores with a combined length of over 3 km was logged using a KT-10 magnetic susceptibility meter. Magnetic mineral phases within the impact melt sheet were analyzed using Raman Spectrometry. The magnetic susceptibility was found to vary from as high as 577x10-3 SI in basement rocks to as low as 0.01x10-3 SI in the melt sheet. Magnetite was found to be the dominant iron oxide mineral phase within all sections of the melt sheet, except in the upper 190 m of MAN-0608, in which no magnetite was found, and hematite was the dominant iron oxide phase. Offset patterns in the magnetic susceptibility logs of the MAN-0501 and MAN-0608 drill cores of the impact melt sheet suggest that MAN-0501 may have been up-faulted 160 m after the solidification of the impact melt sheet.
A petrographic study of samples from cassiterite bearing localities in Central New Brunswick, Fontao, Spain and Echassieres, France
A petrographic study of samples from cassiterite bearing localities in Central New Brunswick, Fontao, Spain and Echassieres, France
by William Bourque, The cassiterite deposits of Central New Brunswick, Fontao Spain, and Echassieres France have been studied petrographically. Comparison of these deposits with those in Cornwall, South West England and Thailand indicated that the Sulpetro, Rocky Brook Main, some parts of Dungarvon, Falls Brook, Todd Mountain, and Burnthill deposits are similar to the Cornwall type deposits. Tin Hill, some parts of Dungarvon, and Fontao deposits are similar to the Thailand deposits. Temperature information, based on cassiterite crystal habit, indicated a range from 600°C to 450°C for the depositional temperature of the cassiterite. Depth of emplacement and lithostatic pressures, based on Strong's (1981) classification of tin deposits, indicated a range from 12,000 to 2,000 meters and from 3.5 to 0.5 kilobars respectively. The activities of K20 and Na20, based on the stability relations in the K20-Na20-A1203-Si02 -H20-HCl system, are highest in the potassium feldspar rich veins of Salpetro and Rocky Brook Main. They were lowest for the muscovite rich samples from Fontao, Tin Hill greisen, and Cleveland greisen. Because a geological report on the Central New Brunswick area indicated the possibility of a common magmatic source for the granite stocks (Irrinki, 1981), a unifying model was devised to explain the genesis of the cassiterite deposits of Central New Brunswick. The origin of each cassiterite deposit and its relation to the other cassiterite deposits in the area, could be explained using this model. From the model, it is suggested that the Cornwall type complex hydrothermal lode deposits like Sulpetro were produced by fractional crystallization of a late stage granite stock. Smaller deposits like at Rocky Brook Main, may be associated with earlier less trace element rich granite stocks, University of New Brunswick. Department of Geology.
A study of anisotropic granodiorite from the 1982 Miramichi earthquake epicentre
A study of anisotropic granodiorite from the 1982 Miramichi earthquake epicentre
by David A. O'Neill, Granodiorite samples taken from the epicentre of the 1982 Miramichi earthquake sequence reveal a parallel network of Mode I (tensile) fractures. These fractures have a marked effect on the mechanical properties of the material as determined by laboratory testing. The action of stress cycling produces a pronounced decrease in strength of the material as permanent strain is accumulated by dilatant behavior. The micro-fractures are believed to have formed in response to a stress regime whose maximum principal stress orientation is approximately horizontal, east-west trending and whose minimum principal stress is vertical., University of New Brunswick. Department of Earth Sciences.
A study of benthonic foraminifera as environmental indicators with particular reference to species of the Northumberland Strait and Buctouche Estuary, New Brunswick
A study of benthonic foraminifera as environmental indicators with particular reference to species of the Northumberland Strait and Buctouche Estuary, New Brunswick
by Marian McNally, Species of benthonic Foraminifera from the Buctouche Estuary, New Brunswick, and the Northumberland Strait in this study show facies and environmental relationships. Samples of the estuarine subfacies have particular foraminiferal composition reflected in species diversity and relative abundance. Foraminiferal assemblages analysed from the Northumberland Strait core show an environmental change from nearshore to open marine. This change is compatible with the effects of the present Holocene marine transgression., University of New Brunswick. Department of Geology
A study of deformed alkali feldspars from a Precambrian shear zone
A study of deformed alkali feldspars from a Precambrian shear zone
by Glenn G. Poirier, The specimens used in this study were quartzofelspathic gneisses collected from an upper amphibolite facies shear zone in the Ontario Gneiss Segment of the Grenville Province and were studied using optical, X-ray and EDS/SEM techniques. Results of these studies have shown that the majority of the deformation was due to ductile deformation which produced a significant amount of plastic strain in the feldspar porphyroclasts. Observations of these deformed porphyroclasts suggest that plagioclase and microcline have been dynamically recrystallized by rotation and progressive misorientation of subgrains within the host crystals. Increased deformation was found to decrease the amount of microcline present in the specimens. Other parameters such as Al-Si ordering and composition (as determined by XRD and EDS) were found to remain fairly constant with increasing deformation., 10 unnumbered pages after page 83, University of New Brunswick. Department of Geology.
A study of sulfides and related minerals from the O' Toole ore horizon, Fortaleza De Minas, Brazil
A study of sulfides and related minerals from the O' Toole ore horizon, Fortaleza De Minas, Brazil
by Peter G. Banks, The O'Toole nickel sulfide orebody is a komatiite-associated deposit located in the Archean Morro do Ferro Greenstone sequence of the Furnas granitoid-greenstone terrain in the Minas Gerais region of Brazil . The ore zone occurs at the base of the upper ultramafic cycle, of which there are four. The ore appears to have accumulated in an embayment, possibly formed by magma-induced thermal erosion, in footwall iron-formation sediments. Four ore types are defined: banded, breccia , matrix and disseminated . The ore mineral assemblage is pyrrhotite –pentlanditechalcopyrite with minor cobaltite-gersdorffite. Oxides include ferro chromite, magnetite and minor ilmenite. Higher concentrations of chromium and cobalt occur in the upper part of the ore zone, while nickel concentrations increase toward the base. The ore has undergone extensive deformation and metamorphism to the amphibolite facies. The postulated peak metamorphic temperature was 525°C with f0 2 at 10-24 (using the solution model of Spencer and Lindsley, 1981). The ore textures are mainly tectonometamorphic, showing syn - as well as post-deformation mineral growth., University of New Brunswick. Department of Geology.
Alteration and related mineralization in the Qalluviartuuq greenstone belt, Northeastern Superior Province, Quebec
Alteration and related mineralization in the Qalluviartuuq greenstone belt, Northeastern Superior Province, Quebec
by Alastair Charles Still, The <2 km wide and about 70 km long Qalluviartuuq greenstone belt consists of mafic and felsic metavolcanic schists, metasediments, and a lens of gabbroic anorthosite <1 km wide and ~3-5 km long. Peak metamorphic grade for the section of the belt studied is low pressure epidote amphibolite facies with retrograde metamorphism in the upper greenschist facies. The mafic metavolcanics classify as basalts to alkaline basalts and contain hornblende - epidote - plagioclase (An33 - An40) ± biotite ± sphene ± magnetite. Quartzofeldspathic metasediments consist of quartz - biotite - plagioclase ±garnet± magnetite ± pyrite± chalcopyrite. The gabbroic anorthosite consists of plagioclase (An60 - An70) ± hornblende± clinopyroxene ± orthopyroxene ± biotite. Plutonic rocks flanking the belt are primarily biotite ± muscovite foliated metagranodiorite which trend NNW and dip steeply to near vertical. Zones of extensive alteration within the mafic metavolcanics and the anorthositic lens contain plagioclase - anthophyllite - cordierite ± biotite ± sericite ± chlorite ±quartz. Within the mafic metavolcanics these altered zones are characterized by enrichments in Fe20 3T and MgO with depletions in K20, Cao, Na20, and Si02. Altered zones of the anorthositic lens are characterized by enrichments in Fe20 3T, MgO, and Na20. These zones are associated with areas of localized ductile deformation characterized by layering of mafic minerals, mylonitization, and kink folding. They are likely brittle-initiated zones of ductile deformation which have undergone recrystallization-accommodated dislocation creep. Sulfide mineralization is associated with ductilely deformed and altered sections of the anorthositic lens and consists of pyrite - chalcopyrite - pyrrhotite ± sphalerite ±magnetite. Mineralization within mafic metavolcanics is characteristic of a Cu-Zn type volcanogenic massive sulfide (VMS) deposit and contains pyrite-pyrrhotite - chalcopyrite ± sphalerite ± magnetite± galena. Mineralized zones have elevated Cu, Zn, and Ag values with localized enrichments in Au and Co., University of New Brunswick. Department of Geology.
Alteration and related mineralization in the Qalluviartuuq greenstone belt, northeastern
Superior Province, Quebec.
Alteration and related mineralization in the Qalluviartuuq greenstone belt, northeastern Superior Province, Quebec.
by Alastair Charles Still, The <2 km wide and about 70 km long Qalluviartuuq greenstone belt consists of mafic and felsic metavolcanic schists, metasediments, and a lens of gabbroic anorthosite <1 km wide and ~3-5 km long. Peak metamorphic grade for the section of the belt studied is low pressure epidote amphibolite facies with retrograde metamorphism in the upper greenschist facies. The mafic metavolcanics classify as basalts to alkaline basalts and contain hornblende - epidote - plagioclase (An33 - An40) ± biotite ± sphene ± magnetite. Quartzofeldspathic metasediments consist of quartz - biotite - plagioclase ±garnet± magnetite ± pyrite± chalcopyrite. The gabbroic anorthosite consists of plagioclase (An60 - An70) ± hornblende± clinopyroxene ± orthopyroxene ± biotite. Plutonic rocks flanking the belt are primarily biotite ± muscovite foliated metagranodiorite which trend NNW and dip steeply to near vertical. Zones of extensive alteration within the mafic metavolcanics and the anorthositic lens contain plagioclase - anthophyllite - cordierite ± biotite ± sericite ± chlorite ±quartz. Within the mafic metavolcanics these altered zones are characterized by enrichments in Fe20 3T and MgO with depletions in K20, Cao, Na20, and Si02. Altered zones of the anorthositic lens are characterized by enrichments in Fe20 3T, MgO, and Na20. These zones are associated with areas of localized ductile deformation characterized by layering of mafic minerals, mylonitization, and kink folding. They are likely brittle-initiated zones of ductile deformation which have undergone recrystallization-accommodated dislocation creep. Sulfide mineralization is associated with ductilely deformed and altered sections of the anorthositic lens and consists of pyrite - chalcopyrite - pyrrhotite ± sphalerite ±magnetite. Mineralization within mafic metavolcanics is characteristic of a Cu-Zn type volcanogenic massive sulfide (VMS) deposit and contains pyrite-pyrrhotite - chalcopyrite ± sphalerite ± magnetite± galena. Mineralized zones have elevated Cu, Zn, and Ag values with localized enrichments in Au and Co., University of New Brunswick. Department of Geology.

Pages

Zircon - This is a contributing Drupal Theme
Design by WeebPal.