Rocky Brook Research Articles

Stratigraphic and Structural Constraints on Limestone Exploration: A Case Study from Northern New Brunswick, Canada

Industrial-grade limestone is found in both the Lower Silurian La Vieille Formation and Upper Silurian LaPlante Formation of the Chaleurs Group in northern New Brunswick. Currently, between 150 000 and 200 000 tonnes of limestone are produced per year from the proximal facies of the LaPlante Formation at the Sormany quarry of Elmtree Resources Ltd., located west of Bathurst. The proximal facies of the LaPlante Formation was deposited on the margins of tectonically uplifted Ordovician terranes. This facies comprises stromatoporoidal-algal bindstone intercalated with wackestone, packstone, and floatstone in variable proportions. The distal facies comprises calcareous shale and minor limestone deposited deeper offshore. Folding and faulting related to Middle Devonian Acadian tectonism have caused an increase in the apparent thickness of the limestone sequences, especially adjacent to the regional Rocky Brook–Millstream fault. Structural and stratigraphic observations indicate that some of the limestone bodies in the area have been tectonically displaced from their site of deposition. A variety of prospecting techniques was used to locate new limestone resources, including geological mapping, airborne and ground electromagnetic surveys, and satellite remote sensing. Clastic rock units above and below the LaPlante Formation have distinctive properties that help to trace the intervening limestone along strike. Because of water-saturated glacial cover, thick vegetation, and the small size of targets, airborne geophysical methods did not prove effective in delineating limestone beds, but aeromagnetic surveys helped map the underlying clastic unit. The remote-sensing data and especially high-resolution digital elevation models helped in identification of karst topography related to limestone.

Stratigraphy, Palynology and Source Rock Potential of Lacustrine Deposits of the Lower Carboniferous (Visean) Rocky Brook Formation, Deer Lake Subbasin, Newfoundland

Stratigraphy, Palynology and Source Rock Potential of Lacustrine Deposits of the Lower Carboniferous (Visean) Rocky Brook Formation, Deer Lake Subbasin, Newfoundland

Analcime in lake and lake‐margin sediments of the Carboniferous Rocky Brook Formation, Western Newfoundland, Canada

ABSTRACTIn the Deer Lake Basin of western Newfoundland, Canada, analcime has been found within fine‐grained, siliciclastic and carbonate, lake and lake‐margin sediments of the Carboniferous Rocky Brook Formation. Analcime is the only zeolite observed in these unmetamorphosed and non‐volcanogenic rocks. Microscopic analcime occurs as vug‐filling, limpid, isotropic to anisotropic crystals. Microprobe analyses show this type of analcime to be lower in silica than most analcime in sedimentary rocks. A second textural type of finer‐grained submicroscopic analcime can be detected from X‐ray diffraction spectra of Rocky Brook Formation mudstones, where it is associated with phyllosilicates (illite, interstratified chlorite/smectite, smectite, chlorite), other silicates (quartz, feldspar) and carbonates (dolomite, calcite). Results of this study suggest that the analcime in the Rocky Brook Formation formed either by direct lakewater/porewater precipitation or by reaction of these waters with one or more clay mineral types or plagioclase.

Geology and geochemistry of the Burnthill Granite and related W – Sn – Mo – F mineral deposits, central New Brunswick

Several significant W – Sn – Mo – F-bearing hydrothermal mineral deposits occur in the Miramichi Highlands of central New Brunswick. These deposits are spatially and temporally related to a group of five subcircular, undeformed, high-level, posttectonic granite plutons (Burnthill, Dungarvon, Rocky Brook, Sisters Brook, Trout Brook) of Middle Devonian age. The largest of the plutons is the Burnthill Granite (area = 180 km2), which comprises a texturally variable, polyphase intrusion composed of biotite monzogranites and alkali feldspar granites (International Union of Geological Sciences (IUGS) classification); apatite and zircon are the ubiquitous accessory minerals. Field and petrographic data indicate that the Burnthill Granite and two small (< 7 km2) adjacent intrusions (Buttermilk Brook and Burnthill Mine granites), located 1 km from the southeast contact of the main intrusion, are genetically related and are epizonal in character. Classic epizonal features include sharp, discordant intrusive contacts with the host metasediments; a narrow contact metamorphic aureole with local zones of intense hydrothermal alteration and mineralization; an isotropic internal fabric; evidence of multiple intrusion; and the presence of porphyries.Geochemically the pluton is composed of mildly peraluminous, high-silica granites (SiO2 > 74 wt. %), with low abundances of TiO2, MgO, CaO, P2O5, Sr, Ba, and Eu, and high concentrations of Y, Nb, Sn, Cs, Ta, W, Th, and U; high FeO/MgO ratios and Na2O + K2O contents are typical. Covariation among many of the major and trace elements within the volumetrically important phases of the Burnthill Granite can be explained by the process of fractional crystallization, and has resulted in an enrichment of those elements of economic interest (viz., Sn and W) in the more evolved granites. However, the anomalous behaviour of certain elements in these most evolved phases requires the operation of an additional process; this was most likely aqueous phase saturation followed by fluid separation, a process whose activity is corroborated by field and petrographic evidence (e.g., the development of miarolitic cavities and myrmekite). Normative Ab–Or–Q–An contents for the Burnthill Granite have a mean compostion of Ab31Or28Q38An3. This average value is almost identical to that of the piercing point assemblage in the "haplogranodiorite" system with 3 % normative anorthite, and is consistent with crystallization under water-saturated conditions at about 1 kbar (100 MPa) and 730–800 °C.Structural and petrochemical data demonstrate that the W – Sn – Mo – F-bearing mineral deposits were deposited in fracture and fault systems that developed after crystallization was completed, from hydrothermal fluids that were compositionally similar (high concentrations of F, Na, K, Sn, W) to the more evolved silicate melt phases of the Burnthill Granite. In addition to generating the wolframite–cassiterite–fluorite mineral deposits that occur in both endo- and exo-granitic settings, these fluids produced zones of intense, fracture-controlled, aluminosilicate alteration (viz., K-feldspathization, albitization, greisenization, and topaz alteration) that envelop the zones of mineralization.

Returns of three year-classes of sea-ranched Atlantic salmon of various river strains and strain crosses

Releases and returns of three year-classes of sea-ranched Atlantic salmon, Salmo salar, of several river strains and strain crosses were examined. Significant ( P < 0.05) year-class and strain effects were found for fork length, day of return, and percent return among grilse and larger salmon and for the percentage of grilse among the returns. In addition, contrasts among pure strains, sire strains, and dam strains were made. Grilse of the Big Salmon River strain and crosses involving the Big Salmon River strain tended to be longest, return latest, and had the highest percent returns. Larger salmon of the Saint John River strain and strain crosses tended to be longest and had the highest percent return. The Big Salmon River and Rocky Brook strains produced higher proportions of grilse than either the Magaguadavic or Saint John River strains. There was no evidence of heterosis from crosses between strains for any of the traits examined. Sire strain means were more similar to pure strain means than were dam strain means. Pseudolinkage in the males is proposed as a possible explanation. Recommendations are made for choosing stocks which are appropriate for sea ranching.

Evidence of an Adaptive Basis for Geographic Variation in Body Morphology and Time of Downstream Migration of Juvenile Atlantic Salmon (Salmo salar)

Differences in growth rate, proximate composition, body morphology, and time of downstream migration between two populations inhabiting tributaries of the Miramichi River, New Brunswick, that differed in distance from the head of tide, temperature, and flow velocity were studied. Rocky Brook, located 132.6 km above the head of tide, had lower temperatures and higher average flow velocities than Sabbies River, located 42.5 km above tide. Growth rate and proximate composition were similar between populations, but body morphology and time of downstream migration differed significantly between populations. Individuals from Rocky Brook had more fusiform bodies and larger paired fins than their counterparts in Sabbies River. Rocky Brook fish also left the tributary in the fall rather than in the spring as was the case in Sabbies River. The generality of the flow regime–body morphology relationship observed was tested and confirmed by predicting differences in morphology of juvenile salmon in other rivers based on a knowledge of their flow regimes. It is suggested that early migration by the Rocky Brook fish is related to the higher energetic costs of overwintering in that stream. We hypothesize that the phenotypic similarity in growth rate and proximate composition and geographic variation in body morphology and timing of migration have an adaptive basis.Key words: geographic variation, polygenic traits, population biology, Atlantic salmon, morphology, migration, proximate composition, growth, adaptation

Evidence of Adaptive Polygenic Variation Between Two Populations of Atlantic Salmon (Salmo salar) Native to Tributaries of the S. W. Miramichi River, N.B.

Breeding experiments were conducted to test the hypothesis that spatial homeostasis in growth and proximate composition and geographic variation in body morphology and timing of migration in juvenile Atlantic salmon (Salmo salar) have an adaptive basis. The populations studied were Rocky Brook and Sabbies River, tributaries of the Southwest Miramichi River, New Brunswick. Growth rates and proximate composition were very similar in the two populations under hatchery conditions. Genetic contributions to homeostasis in these traits were largely additive. The phenotypic expression of migratory behavior and the genetic control of timing were not quantifiable. A genetic basis to interpopulation variation in body morphology was demonstrated. Progeny from Rocky Brook which exhibits higher flows had more fusiform bodies and longer fins than progeny from Sabbies River when reared under identical conditions. Heritable variation in morphology and a demonstrated directional selection for greater fin size in high velocity environments support the hypothesis that these traits are adaptive. Adaptive polygenic variation between local populations stresses the need to delineate stocks on a functional basis so that species can be managed without significant loss of fitness and/or depletion of genetic variation in natural populations.Key words: quantitative genetics, heritability, adaptation, morphology, growth, proximate composition, migration, Atlantic salmon, interdemic variation, directional selection

Geochemistry of volcanic rocks from the Tetagouche Group, Bathurst, New Brunswick, Canada: Discussion

A recent paper by Whitehead and Goodfellow (1978) presented much needed petrochemical data on volcanic rocks of the Ordovician Tetagouche Group in northern New Brunswick. Although analytical results were not tabulated, numerous plots of major and trace elements confirm an earlier suggestion by Davies et al. (1973) that the Tetagouche volcanic rocks are essentially bimodal, and that andesites are rare or absent. The mafic rocks are subdivided into three distinct groups, group A being either tholeiitic or calc-alkaline basalts, groups B and C being alkaline basalts. The dacitic to rhyolitic rocks belong to the calc-alkaline clan. The following model for the evolution of the Tetagouche Group is proposed in their paper: 1. An ocean-floor sequence of basalts formed as a result of the opening of the Proto-Atlantic. Tholeiitic basalts (group A) generated at a ridge are overlain by alkaline basalts (group B) believed to have been deposited in an off-axis environment. 2. During the Ordovician Period subduction started. Tholeiitic and calc-alkaline mafic and intermediate rocks expected to be extruded at the early stages of a developing island arc have not been recognized. They are thought to have been either subducted subsequently to their formation or uplifted and eroded; or they may underlie Carboniferous rocks in the southeast. 3. During continued evolution of the island arc calc-alkaline dacitic to rhyolitic pyroclastic rocks and lavas were deposited directly on the ocean floor (groups A and B). This discussion is not about the petrochemical classifications presented, but intends to show some of the problems arising from geological models established on the basis of petrochemical models without considering existing geological constraints. Although all workers familiar with the Bathurst district would agree that the whole stratigraphic and structural story of the Tetagouche Group has not been told yet, the published literature leaves considerably less room for modeling than the authors have taken. The model ignored the fact that the volcanic rocks of the Tetagouche Group are underlain by a quartz-rich sedimentary sequence (Smith 1957; Poole 1967; Helmstaedt 1971, 1973; Fyffe 1976), which is mainly of Early Ordovician age. Whereever the contact with the overlying volcanic rocks can be observed, the volcanic rocks are acidic, and basic volcanic rocks follow higher in the sequence (Helmstaedt 1971, 1973; Luff 1977). In the northeastern part of the district, where basic volcanic rocks predominate, the stratigraphic relationships to surrounding sedimentary rocks are not always clear. However, the basic volcanic rocks of sample areas 2 and 3 (Whitehead and Goodfellow 1978) are structurally continuous (Skinner 1974), and in area 3 contain interlayered limestones with fossils (Helmstaedt 1971 ; Skinner 1974) younger than those of the lower sedimentary sequence (Fyffe 1976). The basic volcanic rocks near the city of Bathurst (sample area 4) are either similar in age to those in areas 2 and 3 (Skinner 1974), or even younger, as suggested recently by Pajari et al. (1977). Is the model of Whitehead and Goodfellow (1978) compatible with this information? 1. The ocean-floor sequence (group A) in area 2, inferred to be related to the rifting of the ProtoAtlantic and therefore presumably of preOrdovician age, postdates Lower Ordovician metasediments as well as much of the acidic volcanic rocks making up the major volume of the Tetagouche Group. If the group A volcanic rocks represent an environment of rifting, this must be related to a later episode, perhaps back-arc spreading, as the main arc had been established already. So far, no Lower Ordovician ophiolites have been recognized in the Tetagouche Group; however, they are thought to exist in the Elmtree-Fournier inlier north of the Rocky Brook Millstream fault (Pajari et al. 1977). C an . J . E ar th S ci . D ow nl oa de d fr om w w w .n rc re se ar ch pr es s. co m b y Q ue en s U ni ve rs ity o n 05 /0 2/ 14