Geophysical modeling of Devonian plutons in the southern Gulf of St. Lawrence: implications for Appalachian terrane boundaries in Maritime Canada

2007 ◽  
Vol 44 (11) ◽  
pp. 1551-1565 ◽  
Author(s):  
Lori A Cook ◽  
Sonya A Dehler ◽  
Sandra M Barr
Keyword(s):  
Magnetic Anomaly ◽  
Prince Edward Island ◽  
Sedimentary Cover ◽  
Complex Structure ◽  
Physical Property ◽  
Gravity Anomalies ◽  
The South ◽  
Cape Breton Island ◽  
The North ◽  
Cape Breton

A prominent positive magnetic anomaly spans the 100 km distance between Prince Edward Island and Cape Breton Island in the southern Gulf of St. Lawrence. The anomaly occurs in an area of complex structure where Appalachian terrane boundaries are poorly resolved because of thick late Paleozoic sedimentary cover. Analysis of the magnetic anomaly led to the interpretation that it is produced by four separate, approximately circular, source bodies aligned along the northwesterly trend of the anomaly. Seismic data, physical property measurements, and magnetic and gravity anomalies were used to further investigate the anomaly sources through forward modeling techniques. The four source bodies have densities and magnetic susceptibilities compatible with dioritic to granitic compositions. Modeling also suggests that basement to the north of the plutons has higher density and susceptibility than basement to the south, and hence the source bodies are interpreted as plutons emplaced along the boundary between Ganderian composite terranes to the north and the Ganderian Brookville – Bras d’Or terrane to the south. This interpretation suggests that the Ganderia–Avalonia boundary is located farther south, and shows the need for re-evaluation of the location and role of the Canso fault in offsetting terranes between Cape Breton Island and southern New Brunswick.

Frank Campbell MacIntosh, 24 December 1909 - 11 September 1992

1994 ◽  
Vol 40 ◽  
pp. 253-264 ◽  
Keyword(s):  
Nova Scotia ◽  
New England ◽  
Prince Edward Island ◽  
United Church Of Canada ◽  
Cape Breton Island ◽  
North West ◽  
The North ◽  
Cape Breton ◽  
One Year ◽  
North West Territories

The MacIntoshes were displaced from the Western Isles of Scotland by the Highland clearances at the end of the eighteenth century and like many of their compatriots moved to Nova Scotia. Around 1816 the Macintoshes were settled on a farm at Big Harbour Island on the Bras d’Or Lake of Cape Breton Island, that large detached part of Nova Scotia separated from the mainland by the narrow Straits of Canso - so narrow that they were frequently crossed by swimming deer. This part of Nova Scotia had a considerable resemblance to the old home in its landscape and its sea-tom ruggedness, which must have assuaged some of the pain of exile. Frank (who was always known as Hank) was born at Baddeck in Cape Breton on 24 December 1909, the son of the Reverend C.C. Macintosh, a well-known pastor of the United Church of Canada, who spoke and preached in Gaelic in the Canadian Maritimes and in New England. His mother Beenie Matheson, also of Scottish origin, came from Prince Edward Island. She had trained as a teacher and had moved to the north-west territories as a pioneer. As a child Hank frequently went visiting with his father in the horse and buggy. He was a precocious child and taught himself to read at the age of three - largely from the Encyclopedia Britannica - becoming especially interested in the geographical places described therein. At nine he was driving the family Model T. He was very proud of the fact that when he was just one year old, Alexander Graham Bell dandled him on his knee at his home in Beinn Bhreagh.

Geodynamics of the France Southeast Basin

2010 ◽  
Vol 181 (6) ◽  
pp. 477-501 ◽  
Author(s):  
Xavier Le Pichon ◽  
Claude Rangin ◽  
Youri Hamon ◽  
Nicolas Loget ◽  
Jin Ying Lin ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Sedimentary Cover ◽  
Central Basin ◽  
The South ◽  
Western Basin ◽  
Active Deformation ◽  
The North ◽  
The Alps ◽  
Sediment Cover ◽  
Surrounding Areas

AbstractWe investigate the geodynamics of the Southeast Basin with the help of maps of the basement and of major sedimentary horizons based on available seismic reflection profiles and drill holes. We also present a study of the seismicity along the Middle Durance fault. The present seismic activity of the SE Basin cannot be attributed to the Africa/Eurasia shortening since spatial geodesy demonstrates that there is no significant motion of Corsica-Sardinia with respect to Eurasia and since gravitational collapse of the Alps has characterized the last few millions years. Our study demonstrates that the basement of this 140 by 200 km Triassic basin has been essentially undeformed since its formation, most probably because of the hardening of the cooling lithosphere after its 50% thinning during the Triassic distension. The regional geodynamics are thus dominated by the interaction of this rigid unit with the surrounding zones of active deformation. The 12 km thick Mesozoic sediment cover includes at its base an up to 4 km thick mostly evaporitic Triassic layer that is hot and consequently highly fluid. The sedimentary cover is thus decoupled from the basement. As a result, the sedimentary cover does not have enough strength to produce reliefs exceeding about 500 to 750 m. That the deformation and seismicity affecting the basin are the results of cover tectonics is confirmed by the fact that seismic activity in the basin only affects the sedimentary cover. Based on our mapping of the structure of the basin, we propose a simple mechanism accounting for the Neogene deformation of the sedimentary cover. The formation of the higher Alps has first resulted to the north in the shortening of the Diois-Baronnies sedimentary cover that elevated the top of Jurassic horizons by about 4 km with respect to surrounding areas to the south and west. There was thus passage from a brittle-ductile basement decollement within the higher Alps to an evaporitic decollement within the Diois-Baronnies. This shortening and consequent elevation finally induced the southward motion of the basin cover south of the Lure mountain during and after the Middle Miocene. This southward motion was absorbed by the formation of the Luberon and Trévaresse mountains to the south. To the east of the Durance fault, there is no large sediment cover. The seismicity there, is related to the absorption of the Alps collapse within the basement itself. To the west of the Salon-Cavaillon fault, on the other hand, gravity induces a NNE motion of the sedimentary cover with extension to the south and shortening to the north near Mont Ventoux. When considering the seismicity of this area, it is thus important to distinguish between the western Basin panel, west of the Salon-Cavaillon fault affected by very slow NNE gliding of the sedimentary cover, with extension to the south and shortening to the north; the central Basin panel west of the Durance fault with S gliding of the sedimentary cover and increasing shortening to the south; and finally the basement panel east of the Durance fault with intrabasement absorption of the Alps collapse through strike-slip and thrust faults.

scholarly journals New and noteworthy records of Orthoptera and allies in the Maritimes and the Îles-de-la-Madeleine, Quebec

2014 ◽  
Vol 127 (4) ◽  
pp. 332 ◽  
Author(s):  
Paul M. Catling ◽  
Donald F. McAlpine ◽  
Christopher I. G. Adam ◽  
Gilles Belliveau ◽  
Denis Doucet ◽  
...  
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Prince Edward Island ◽  
Forficula Auricularia ◽  
Cape Breton Island ◽  
Cape Breton ◽  
La Madeleine

Chortophaga viridifasciata, Forficula auricularia, Melanoplus stonei, Scudderia furcata furcata, Scudderia pistillata, and Trimerotropis verruculata from Prince Edward Island and Doru taeniatum, Melanoplus punctulatus, Orchelimum gladiator, and Spharagemon bolli from New Brunswick are new provincial records. Other records of interest include the endemic Melanoplus madeleineae from Île d’Entrée in the Îles-de-la-Madeleine, Quebec; Trimerotropis verruculata from the Îles-de-la-Madeleine, Quebec; and Chortophaga viridifasciata, Stethophyma lineatum, and Tetrix subulata, new for Cape Breton Island, Nova Scotia. The ranges of Conocephalus brevipennis, Tetrix arenosa angusta, Tetrix ornata, and Tetrix subulata are significantly extended in New Brunswick. A previously unpublished record from 2003 of Roeseliana roeselii (Metrioptera roeselii) is the earliest report of this European introduction to the Maritimes.

scholarly journals Oligocene-Miocene extension led to mantle exhumation in the central Ligurian Basin, Western Alpine Domain

2019 ◽  
Author(s):  
Anke Dannowski ◽  
Heidrun Kopp ◽  
Ingo Grevemeyer ◽  
Dietrich Lange ◽  
Martin Thowart ◽  
...  
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Seafloor Spreading ◽  
Wide Angle ◽  
The South ◽  
Seismic Line ◽  
Acoustic Basement ◽  
North West ◽  
The North ◽  
Ligurian Basin

Abstract. The Ligurian Basin is located in the Mediterranean Sea to the north-west of Corsica at the transition from the western Alpine orogen to the Apennine system and was generated by the south-eastward trench retreat of the Apennines-Calabrian subduction zone. Late Oligocene to Miocene rifting caused continental extension and subsidence, leading to the opening of the basin. Yet, it still remains enigmatic if rifting caused continental break-up and seafloor spreading. To reveal its lithospheric architecture, we acquired a state of the art seismic refraction and wide-angle reflection profile in the Ligurian Basin. The seismic line was recorded in the framework of SPP2017 4D-MB, the German component of the European AlpArray initiative, and trends in a NE-SW direction at the centre of the Ligurian Basin, roughly parallel to the French coastline. The seismic data recorded on the newly developed GEOLOG recorder, designed at GEOMAR, are dominated by sedimentary refractions and show mantle Pn arrivals at offsets of up to 70 km and a very prominent wide-angle Moho reflection. The main features share several characteristics (i.e. offset range, continuity) generally associated with continental settings rather than documenting oceanic crust emplaced by seafloor spreading. Seismic tomography results are augmented by gravity data and yield a 7.5–8 km thick sedimentary cover which is directly underlain by serpentinised mantle material at the south-western end of the profile. The acoustic basement at the north-eastern termination is interpreted to be continental crust, thickening towards the NE. Our study reveals that the oceanic domain does not extend as far north as previously assumed and that extension led to extreme continental thinning and exhumation of sub-continental mantle which eventually became serpentinised.

The distribution, zoogeography, and composition of Prince Edward Island Carabidae (Coleoptera)

2008 ◽  
Vol 140 (1) ◽  
pp. 128-141 ◽  
Author(s):  
Christopher G. Majka ◽  
Yves Bousquet ◽  
Christine Noronha ◽  
Mary E. Smith
Keyword(s):  
Introduced Species ◽  
Prince Edward Island ◽  
Large Scale ◽  
Management Practices ◽  
Maritime Provinces ◽  
Cape Breton Island ◽  
History Of Collecting ◽  
Cape Breton ◽  
History Of ◽  
Faunal List

AbstractFourteen species of Carabidae are added to Prince Edward Island’s (P.E.I.) faunal list, bringing the known fauna to 167 species. Bembidion nitidum (Kirby) and Bembidion obtusum Audinet-Serville are newly recorded for the Maritime Provinces. Six species are removed from P.E.I.’s faunal list. The history of collecting of Carabidae on P.E.I. is briefly recounted. Despite differences in land area and distance from the mainland between P.E.I., Cape Breton Island, and insular Newfoundland, their carabid faunas exhibit many similarities in size and composition. The native carabid fauna of P.E.I. comprises 49% of the species in the combined Maritime Provinces fauna, perhaps reflecting an island-related diminution of species diversity. The proportion of flightless species on P.E.I. (4.9%) is less than that in the Maritime Provinces as a whole (7.1%), an apparent indication that the Northumberland Strait has been a barrier to colonization. Twenty-seven introduced species are found on P.E.I., 26 of which can be classified as synanthropic and may have originated in dry-ballast quarries in southwestern England. Although the earliest dates of detection of many introduced species on P.E.I. are substantially later than elsewhere in the Maritimes, this reflects the paucity of early collecting. Land-management practices on P.E.I. (large-scale and early forest clearances, intensive agriculture, and the extensive use of biocides) may have had an impact on P.E.I.’s carabid fauna.

The age of igneous and metamorphic events in the western Cape Breton Highlands, Nova Scotia

1986 ◽  
Vol 23 (12) ◽  
pp. 1891-1901 ◽  
Author(s):  
R. A. Jamieson ◽  
O. van Breemen ◽  
R. W. Sullivan ◽  
K. L. Currie
Keyword(s):  
Metamorphic Rocks ◽  
Western Cape ◽  
Cape Breton Island ◽  
Late Proterozoic ◽  
The North ◽  
Cape Breton ◽  
Gneiss Complex ◽  
Form Part ◽  
Plutonic Rocks ◽  
High Level

Plutonic rocks of four different ages have been recognized in the Cape Breton Highlands on the basis of U–Pb dating of zircons. Two plutons, the North Branch Baddeck River leucotonalite [Formula: see text] and the Chéticamp pluton (550 ± 8 Ma), give dates that fall within the range of Late Proterozoic to Cambrian ages considered characteristic of the Avalon tectonostratigraphic zone of the eastern Appalachians. Late Ordovician to Silurian tonalite (Belle Côte Road orthogneiss, 433 ± 20 Ma) was metamorphosed, deformed, and incorporated into the central Highlands gneiss complex by approximately 370–395 Ma. High-level subvolcanic plutons (Salmon Pool pluton, [Formula: see text]) postdate all metamorphic rocks in the area. The presence of the older plutons is consistent with interpretation that the Cape Breton Highlands form part of the Avalon zone, but the presence of Ordovician–Silurian plutonic rocks and Devonian amphibolite-facies metamorphism is anomalous in comparison with the Avalon zone of Newfoundland and southeastern Cape Breton Island. Terranes with similar Late Proterozoic to mid-Paleozoic plutonic and metamorphic histories form a discontinuous belt along the northwest side of the Avalon zone southwest of Cape Breton Island. These rocks probably reflect events during and after the accretion of the Avalon zone to North America.

Accumulation Models of the Oil Pools of Block XXI of Tamsag Basin in Mongolia

2014 ◽  
Vol 962-965 ◽  
pp. 522-525
Author(s):  
Liang Zhao
Keyword(s):  
Water Distribution ◽  
Physical Property ◽  
Reverse Fault ◽  
The South ◽  
Hydrocarbon Migration ◽  
The North ◽  
Oil Water ◽  
Migration Pathways

This document explains different tectonic styles and sedimentary fillings give rise to the different accumulation combinations and accumulation models between the south and the north frogs of East Subsag of South Buir Sag. The Tsagaantsav Formation oil pools, subject to the rupture of the fault-period tectonic layers, has developed multiple types of traps including reverse fault blocks, fault noses and drag anticlines. They are close to the oil-generating sags, in the indicator areas of hydrocarbon migration where hydrocarbon pools, particularly tectonic-controlled pools, are easily formed. The lithology and physical property play an important controlling role over the formation of oil pools with complicated oil-water distribution relationship. The constant and the late active ruptures as longitudinal hydrocarbon migration pathways, together with the sedimentary sands of multiple genesis types, have given shape to the multi-formation lithologic, lithologic-tectonic or tectonic accumulation combinations.

Tremadocian (Lower Ordovician) sea-level changes and biotas on the Avalon microcontinent

2011 ◽  
Vol 85 (4) ◽  
pp. 678-694 ◽  
Author(s):  
ED Landing ◽  
Richard A. Fortey
Keyword(s):  
Sea Level ◽  
Sea Level Changes ◽  
Low Oxygen ◽  
Cape Breton Island ◽  
Lower Upper ◽  
The North ◽  
Cape Breton ◽  
Lower Ordovician ◽  
Bottom Waters ◽  
History Of

The Chesley Drive Group, an Upper Cambrian-Lower Ordovician mudstone-dominated unit, is part of the Ediacaran–Ordovician cover sequence on the North American part of the Avalon microcontinent. The upper Chesley Drive Group on McLeod Brook, Cape Breton Island (previously “McLeod Brook Formation”), has two lithofacies-specific Tremadocian biotas. An older low-diversity benthic assemblage (shallow burrowers, Bathysiphon, phosphatic brachiopods, asaphid trilobites) is in lower upper Tremadocian green-gray mudstone. This wave-influenced, slightly dysoxic facies has Bathysiphon–brachiopod shell lags in ripple troughs. The upper fauna (ca. 483 +/- 1 Ma) is in dysoxic-anoxic (d-a), unburrowed, dark gray-black, upper upper (but not uppermost) Tremadocian mudstone with a “mass kill” of the olenid Peltocare rotundifrons (Matthew)—a provincial trilobite in Avalonian North America that likely tolerated low oxygen bottom waters. Scandodus avalonensis Landing n. sp. and Lagenochitina aff. conifundus (Poumot), probable nektic elements and the first upper Tremadocian conodont and chitinozoan reported from Avalon, occur in diagenetic calcareous nodules in the dark gray-black mudstone. An upper Tremadocian transition from lower greenish to upper black mudstone is not exposed on McLeod Brook, but is comparable to a coeval green-black mudstone transition in Avalonian England. The successions suggest that late late Tremadocian (probable Baltic Hunnebergian Age) sea level was higher in Avalon than is suggested from successions on other paleocontinents. The Tremadocian sea-level history of Avalon was a shoaling-deepening-shoaling sequence from d-a black mudstone (lower Tremadocian), to dysoxic green mudstone (lower upper Tremadocian), and back to black mudstone (upper upper Tremadocian).Scandodus Lindström is emended, with the early species S. avalonensis Landing n. sp. assigned to the emended Family Protopanderodontidae. Triangulodus Van Wamel is considered a junior synonym of Scandodus. Peltocare rotundifrons is emended on the basis of complete specimens.

Integrated geologic and geophysical interpretation of the Buraco da Velha copper deposit (Rondônia, Brazil): A basis for exploring in related environments

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. B121-B133
Author(s):  
Vinicius Hector Abud Louro ◽  
Marta Silvia Maria Mantovani ◽  
Vanessa Biondo Ribeiro
Keyword(s):  
Magnetic Anomaly ◽  
Gamma Ray ◽  
Sedimentary Cover ◽  
Copper Deposit ◽  
Magnetization Direction ◽  
The North ◽  
Copper Mineralization ◽  
Geophysical Interpretation ◽  
High Gamma ◽  
Magnetic Model

The Buraco da Velha copper deposit lies at the northern limit of the Parecis Basin in the Colorado Graben, Rondônia, Brazil. New geophysical data indicate the presence of a magnetic source below and to the north of the Buraco da Velha deposit, where it corresponds with high gamma-ray U, Th, and K counts. We have studied the source of the magnetic anomaly and delineated it through derivative transforms, Euler deconvolution, MaxiMin total magnetization direction analysis, staged inverse modeling, Th/K ratio, and radiometric ternary imaging. The magnetic anomaly is elongated in the east–west direction and measures [Formula: see text], and the top of the source is estimated to lie at depths mostly between 50 and 100 m. Based on the magnetic model, we indirectly estimate a Jurassic to Cretaceous age, which is compatible with the 180–80 Ma range dated for the copper mineralization. Gamma-ray data are consistent with the hydrothermal alteration in the sedimentary cover and with the presence of an intrusion in the subsurface. We suggest that the intrusion of the magnetic body generated the necessary thermal energy to mix an already oxidized brine and sulfide-bearing fluids at the border of the Parecis Basin, leading to copper deposition and providing a potential analog for similar environments of mineral deposits elsewhere, such as in the Kupferschiefer deposit (Poland) and the Zambia Copper Belt (Zambia).

scholarly journals Vegetation and Climate of Maritime Canada 6000 Years BP: A Synthesis

2007 ◽  
Vol 49 (1) ◽  
pp. 141-162 ◽  
Author(s):  
Hélène Jetté ◽  
Robert J. Mott
Keyword(s):  
New Brunswick ◽  
Prince Edward Island ◽  
Deciduous Forest ◽  
White Pine ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Complete Sequences ◽  
Maritime Canada ◽  
High Elevations ◽  
Vegetation And Climate

ABSTRACT Environmental conditions (vegetation and climate) of Maritime Canada are reconstructed as a regional contribution to a national synthesis on the paleoenvironment of Canada 6000 yr BP. Ten new sites, including three complete sequences and seven short sequences bracketing the 6 ka period, are added to the existing pollen dataset for this region. The vegetation prevalent 6000 yr BP in New Brunswick was a mixed coniferous-deciduous forest with pine, mostly white pine (Pinus strobus) in the northwest, and a mixed coniferous-deciduous forest with hemlock (Tsuga canadensis) in the south and southeast. In the northwest, fir (Abies) replaced pine at high elevations and a boreal forest grew on the New Brunswick Highlands. The dominant vegetation at 6000 yr BP in Prince Edward Island and Nova Scotia was a mixed coniferous-deciduous forest with hemlock dominating. Cape Breton Island was covered by a mixed coniferous-deciduous forest with pine and/or fir, except for the southern part of the Island where hemlock was probably present. Analysis of the fossil sites indicate that a warm-dry period influenced the composition of the vegetation 6000 yr BP.

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