Southern Labrador Research Articles

Long-term Coastal Occupancy between Cape Charles and Trunmore Bay, Labrador

Ninety-three prehistoric components were discovered during this first comprehensive archaeological survey of the Labrador coastline between Cape Charles and Trunmore Bay. The newly discovered sites show that there was continuous prehistoric occupation from northern Labrador through to the Quebec North Shore and the island of Newfoundland, with radiocarbon dates ranging from 5070±170 to 1050±50 B.P. Dates from Late Palaeoeskimo sites suggest that Middle Dorset occupation of southern Labrador may have begun as early as 1940±70 B.P. and lasted until 1050±50 B.P. Comprehensive survey strategy revealed three broad trends of prehistoric land use and occupation in southern Labrador: the inner coastal zone, in particular the coastline of the largest bays, does not retain any traces of prehistoric coastal occupation; coastal presence by all culture groups is concentrated at or near the mouths of bays and the outer island archipelagoes; and certain coastal locations were preferred areas of land use for prehistoric peoples. At a more specific level, prehistoric Indian sites tend to be situated in protected locations, oriented to both mainland and saltwater resources. Groswater Palaeoeskimo and Late Palaeoeskimo sites, on the other hand, have a decided outer island orientation, which suggests an adaptive focus on saltwater resources. A brief summary of the historic sites recorded during the survey is included. Key words: Southern Labrador, prehistoric sites, culture history, systematic survey, prehistoric Indian versus Palaeoeskimo subsistence-settlement systems, extended Middle Dorset occupation

A New Frontier Province Offshore Northwest Greenland: Structure, Basin Development, and Petroleum Potential of the Melville Bay Area

In the Melville Bay area, offshore northwest Greenland, very large structures and sedimentary basins, which were predicted many years ago on the basis of magnetic and gravity data, have been confirmed by a recent reconnaissance seismic survey, with implications that are encouraging for petroleum exploration in the area. The Melville Bay area flanks a small ocean basin in Baffin Bay that is thought to have formed by oblique sea-floor spreading in the Eocene. There are two major, coast-parallel basins in the area. The inner basin, the Melville Bay Graben, is essentially a half graben with a maximum thickness of sediments exceeding 13 km. A complex fault- controlled ridge system separates this basin from the outer Kivioq Basin in which up to 7 km of sediments have accumulated. By analogy with onshore geology in the surrounding areas and well data from the continental shelves off southern west Greenland and Labrador to the south, it is expected that the first phase of rifting and sedimentation took place in the Early-middle Cretaceous, while a second phase of rifting took place in the latest Cretaceous and early Paleocene. Later, compression and inversion affected the northern part of the area, leading to the formation of large anticlinal structures. ©Copyright 1997. The American Association of Petroleum Geologists. All rights reserved.1Manuscript received January 30, 1996; revised manuscript received September 9, 1996; final acceptance January 21, 1997. 2GeoArctic Consulting Ltd., 1620 9th Street NW, Calgary, Alberta T2M 3L4, Canada. 3Nunaoil A/S, Pilestraede 52, DK-1112 Copenhagen, Denmark. 4Geological Survey of Denmark and Greenland, Thoravej 8, DK-2400 Copenhagen, Denmark. We wish to acknowledge the companies partaking in the KANUMAS project: BP, Exxon, Japan National Oil Company, Shell, Statoil, and Texaco, for allowing us the opportunity to publish this paper. Our thanks also to Rene Forsberg and Simon Ekholm, National Survey and Cadastre, for processing the gravity data for the paper, and to Alan Menelly (consultant) for discussions on the structural development of the area. Airborne gravity data were made available courtesy of John Brozena of the U.S. Naval Research Laboratory.

Modeling the Mean Circulation of the Labrador Sea and the Adjacent Shelves

Abstract A linear three-dimensional diagnostic model is used to study several aspects of the mean circulation of the Labrador Sea and the adjacent shelves: volume transport, three-dimensional structure of currents, mesoscale features produced by JEBAR, winter surface current derived from ice drift data, difference between summer and winter circulation, and effects of buoyancy and local wind on the circulation. The summer circulation is forced by a sea surface elevation at the northern boundary, tuned to produce a 35 Sv (Sv≡106 m3 s−1) total southward transport (including the shelf, the Labrador Current, and the deep sea transports) across the Hamilton Bank section. A comparison of the model results with data collected over the shelves indicates that the model is able to reproduce the major features of the observations. Buoyancy effects on the circulation are found to be more important in the southern Labrador Sea than in the northern Labrador Sea. The subbasin-scale currents give rise to an alongshelf var...

Current meter observations from the Labrador and Newfoundland shelves and comparisons with barotropic model predictions and IIP surface currents

Abstract Recent current measurements from the southern Labrador and northeastern Newfoundland shelves confirm the presence of inshore and offshore branches of the Labrador Current with high mean currents and low standard deviations. At mid‐shelf weaker and more variable currents occur over the banks, and cross‐shelf flows are found to be associated with the shelf topography. An annual cycle of the inshore branch, in phase with wind forcing, is significant on the NE Newfoundland Shelf but not detectable on Hamilton Bank. The phase of the annual cycle in the offshore branch is consistent with buoyancy, not wind forcing. The observations compare reasonably well with results from a barotropic model for the region and the International Ice Patrol (IIP) surface current map. Differences occur particularly in regions of high bathymetrie curvature or an ill‐defined shelf break. The model location of the Labrador Current lies inshore of that indicated by the data, suggesting the need for better definition of the no...

Annual to decadal-scale variations in northwest Atlantic sector temperatures inferred from Labrador tree rings

Temperature-sensitive maximum latewood density chronologies from sites near tree line in Labrador are used to infer past changes in warm-season surface air and sea surface temperatures for the northwest Atlantic. Temperatures are reconstructed for the Grand Banks region based on density records from southern Labrador, while a density series from near Okak Fiord, northern Labrador, is used to infer past temperature variations for north-coastal Labrador and the adjacent Labrador Sea. The Labrador chronologies show good agreement with annual and decadal-scale temperature fluctuations over the recent period of instrumental record, and extend this temperature information into the past by several centuries. The lowest density value at the Okak site occurs in 1816, known as the "year without a summer" in eastern North America. Spectral analyses reveal statistically significant variations with periods of around 8.7, 18–22, and 45–66 years. These fluctuations are in general agreement with those identified in several instrumental and modeling analyses of North Atlantic climate.

Was an increase in natural mortality responsible for the collapse off northern cod?

The collapse of the northern Atlantic cod (Gadus morhua) fishery off southern Labrador and to the northern Grand Bank of Newfoundland, once the largest cod fishery in the world, was a social and economic disaster for the region. An analysis of traditional catch-at-age data in conjunction with research surveys, which assumed that research survey estimation errors of abundance by age and year were independent, led assessment biologists to the conclusion that the collapse was caused by an increase in natural mortality in the first half of 1991. We constructed a statistical model to test this hypothesis. The results do not support the hypothesis. There is ambiguous evidence that natural mortality has increased since 1991; however, these results are found only in a model that has extraordinary patterns in the residuals. Our analysis suggests that even if natural mortality has been higher in recent years (as estimated using a model with correlated errors for research surveys), overfishing was sufficiently high to cause a collapse of this population. We also demonstrate that the usual assumption that estimation errors from research trawl surveys are independent is not valid, and can lead to invalid inference and unreasonable estimates of abundance.

Transhumance among European Settlers in Atlantic Canada

Until recently in Newfoundland, southern Labrador and an adjoining part of Qu6bec, many of the coastal fishing population regularly migrated to the forests or other zones for the winter. The principal motivations were: firewood, shelter, hunting, fur-trapping and fishery gear production. This was one of several forms of seasonal migration by families and communities that characterized the area for nearly three centuries. The practice, unusual among European settlers, was rooted in various environmental, economic and political features. It had important effects on the processes of adaptation and colonization in the region.

Surface oceanographic changes in the eastern Labrador Sea: Nannofossil record of the last 31,000 years

Calcareous nannofossils in two AMS 14C dated piston cores from the eastern Labrador Sea yield oceanographic information of the last 31 kyr. Moderate nannofossil productivity and abundance of North Atlantic warm water taxa in the southern Labrador Sea (core 91-045–094P) suggest cool surface ocean condition between 31 and 26 thousand years ago (ka). The Irminger Current was absent in this interval. Thus we attribute this cool condition to weak advection of North Atlantic water from the southeast. We found evidence of cold and/or seasonally ice-covered surface conditions between 26 and 13 ka in the southern Labrador Sea and between 31 and 12.6 ka in the northeastern Labrador Sea (core 90-013-013P). Increase of nannofossil productivity and abundance of North Atlantic taxa at about 10.7 ka in core 91-045–094P suggests that the southern Labrador Sea was influenced by warm North Atlantic surface water. The polar water of the Labrador Current had little or no influence on the surface ocean in this area before 9 ka. The Labrador Current started to flow or intensify after 9 ka and became strong by 8.4 ka. The northeastern Labrador Sea remained cold until 8.4 ka perhaps because of discharge of cold meltwater from the Greenland ice sheet. At this time, productivity increased sharply and the assemblage of nannofossils changed. These suggest a significant improvement in surface ocean conditions and the establishment of the warm Irminger Current, which marked the onset of the modern circulation pattern characterized by warm West Greenland Current and strong Labrador Current.

Distribution of Capelin (Mallotus villosus) in Relation to Coastal Upwelling in the Avalon Channel

Three hypotheses were developed from a series of studies of capelin (Mallotus villosus) distribution in the southern Labrador Current. The hypotheses were that: (1) water mass replacement due to coastal upwelling occurs at the spatial scale predicted by the balance between buoyant and Coriolis forces; (2) upwelling generates a cross-shore gradient in capelin abundance; and (3) this gradient decays after an episode of upwelling favorable winds. An initial experiment, reported elsewhere, confirmed these predictions for a single strong episode of upwelling favorable winds ending 2 July 1987. To determine whether these predictions hold for typical upwelling events, closer to the average strength, the experiment was repeated during the period of high capelin abundance (mid-June to mid-July) over a 3 year period. The first hypothesis, of wind driven water mass replacement, was confirmed in 29 out of 30 cases where a test was possible. The average lateral extent of cold water near the coast was 5 km as predicted. A gradient in capelin abundance (higher abundance near the coast) was observed at this scale in 13 out of 15 instances, confirming the second hypothesis. The gradient changed in response to upwelling during the strong event in early July of 1987, and in another event during mid-July of 1988. On average, however, the gradient changed in the expected direction in only 2 out of 7 instances where a test was possible. Repeated observational experiments showed that capelin respond to strong upwelling events (sea surface temperature less than 2°C) but do not respond to more typical events.

Relationships between temperature and landing patterns in the southern Labrador and eastern Newfoundland inshore cod fishery

The temporal pattern of cod landings in the inshore trap fishery off the east coast of Newfoundland and Labrador is examined in this study. Unlike previous studies which have been broad scale or of a localized nature, this analysis looks at variations within fishing seasons and among fishing areas in trap landings. A significant relationship between water temperature and the weekly pattern is demonstrated. Significant spatial patterns in weekly landings are described and related to longshore differences in the seasonal variation in temperature.

Gravity, flexure, and the deep structure of the Grenville Front, eastern Quebec and Labrador

The Grenville Front in eastern Quebec and southern Labrador is characterized by a large negative Bouguer gravity anomaly with flanking highs. Forward flexural modelling of this anomaly provides constraints on the deep structure of the eastern Grenville. The Grenville Front is assumed to mark the surface trace of a boundary between less dense crust to the northwest and more dense crust to the southeast, with constant dip all the way to the Moho. An end load is applied to the northwestern plate to simulate the effect of orogenic and (or) subsurface loads, but is then removed underneath a continuous plate to simulate the transient nature of the load. This simple model yields good fits to the gravity anomaly, provided the effective elastic thickness of the lower plate is less than about 30 km and the crustal boundary dips at about 20°. The deep structure of the eastern Grenville Front may therefore be dominated by a major shallow-dipping straight thrust. The applied end loads for the best-fitting models are only a few tens of kilometres southeast of the Grenville Front. This may reflect the former presence of allochthonous crust at and near the present Grenville Front in the eastern Grenville, or delamination of the lithospheric mantle of the northern plate from its overlying mantle, which could also be responsible for the low modelled elastic thicknesses. The absence of a similarly pronounced gravity anomaly in the western Grenville may reflect a lower orogenic load, as evidenced by the absence of a fold-and-thrust belt there, and a steeper dip for the crustal boundary.

Episodes of Ice Rafted Debris and Their Effects on Primary Productivity in the Labrador Sea for the Past 31,000 Years

The Pleistocene has undergone abrupt climatic changes from cold to warm periods within short time intervals as revealed by ice core records (e.g. Dansgaard et al., 1993). These climatic changes have been associated with growth and decay of the Laurentide and Greenland ice sheets as well as changes in the magnitude of deep water formation (Hay, 1993). During disintegration of the Laurentide ice sheet, enormous amounts of fresh meltwater and ice rafted debris were introduced to the northern Atlantic through the Gulf of St. Lawrence and the Hudson Strait (Teller, 1990; Bond et al., 1992). Although episodes of high input of ice rafted debris have been reported based on grain size distributions and calcium carbonate contents (Hillaire-Marcel et al., 1994 and references therein), the stable isotopic compositions of organic carbon and nitrogen have not been used as a tool to characterize these episodes. Furthermore, detailed documentation of primary productivity response to the episodes of iceberg and meltwater input to the Labrador Sea using stable isotopes is lacking. Therefore, the stable isotopic compositions of organic carbon and nitrogen in conjunction with content of organic carbon and CaCO3 for piston core HU-91-045-94 (50~ 45~ and 3440 m water depth) in the southern Labrador Sea, are used to document changes in the type and source of organic matter input, variation in primary productivity and episodes of ice rafted debris deposition for the last 31 kyrs. The chronology of the core has been obtained using both 14C AMS dating and oxygen isotopes (Hillalre-Marcel et al., 1994).

Reconnaissance isotopic geochemistry of anorthosite mangerite-charnockite-granite (AMCG) complexes, Grenville Province, Canada

Anorthosite-mangerite-charnockite-granite (AMCG) complexes with ages of 1.13–1.16 Ga constitute the most widespread and voluminous igneous suites in the Grenville Province. The complexes are widely believed to comprise mantle-derived anorthosite and related basic rocks together with mangerites, charnockites and granites of largely crustal origin. This paper presents results of geochemical and Nd, Sr and Pb isotopic studies of basic and silicic samples from five AMCG complexes in the Grenville Province. Anorthositic members all have positive ϵ Nd (+0.8 to +4.5) indicating time-integrated incompatible element depleted sources, in agreement with earlier studies. Most granitoid samples, with one notable exception, also have positive ϵ Nd (+1.6 to +3.4) indicating sources with short crustal residence times. Granitoids from the Atikonak River complex in southern Labrador have ϵ Nd −3.7 to −2.2 revealing clear evidence that partial melting of relatively old crust was involved in their formation. For both anorthositic and granitoid samples there is broad correlation of decreasing ϵ Nd with increasing Sr i imparting confidence in a model requiring at least two fundamentally different end-members. Isotopic studies of these Grenville Province AMCG complexes, excluding Atikonak, are in accord with a two-source origin in which the crustal sources were not more than a few hundred Ma old at the time they were partially melted; however, a single source origin is not excluded for complexes like Mealy Mountains that evidently developed in newly-formed crust. The petrology and geochemistry of AMCG complexes is broadly consistent with processes whereby crustal partial melting at depth is driven by proximity to basic magma. Extraction of granitoid partial melts is expected to leave crustal residues of appropriate composition to produce anorthositic magmas when assimilated by subjacent basic magmas.

Annual Velocity Variations in the Labrador Current

Abstract Analyses of CTD and current meter data obtained between 1978 and 1988 off southern Labrador reveal two distinct regimes in the Labrador Current. The first lies over the shelf and upper slope and is the traditional Labrador Current transporting cold low-salinity water south from Baffin Bay and Hudson Strait. The main branch of this flow, located over the shelf break, exhibits an annual variation in speed with a minimum in March–April and a maximum in October. Historical temperature and salinity data suggest this variation is related to the fact that the annual variation in steric height is 0.1 m greater over the continental shelf than over the deep ocean. The greater amplitude over the shelf is due to the large salinity variations induced by the additional freshwater in spring and summer, which is largely confined to the waters over the shelf. The effect of the annual variation in salinity is also examined through diagnostic estimates of the Joint Effect of Baroclinicity and Relief (JEBAR). These ...

Late-18th- and Early-19th-Century Inuit and Europeans in Southern Labrador

The Inuit presence, except at Red Bay, is not archaeologically visible until the end of the 18th century, despite the written accounts that document their presence in the Strait of Belle Isle from as early as the 16th century. It appears that they were attracted by the increased European fishing activities in the area. The European presence consisted of fishermen (planter fishermen) posted at the best fishing locations in the Strait of Belle Isle. They adopted a housing style borrowed from the Labrador Inuit, and that trait is notable for the period between the last decade of the 18th century into the middle of the 19th century. The similarities observed between the two ethnic groups demonstrate how complex it is to differentiate them, as a result of cross-acculturation. The Inuit living in close proximity to European stations replaced their traditional material culture with European-made goods in a very short time period, while the European settlers were building sod houses identical to what we know of the 19th-century Labrador Inuit.Key words: Strait of Belle Isle, Labrador Inuit, Europeans, acculturation, historical archaeology, sod houses, 18th-19th century

Greenland halibut ( Reinhardtius hippoglossoides) off Southern Labrador and Northeastern Newfoundland (Northwest Atlantic) feed primarily on capelin ( Mallotus villosus)

Stomachs were collected from 10 300 Greenland halibut ( Reinhardtius hippoglossoides) caught during the autumns of 1981, 1982 and 1984 on the continental shelf and upper slope off southern Labrador and northeastern Newfoundland (northwest Atlantic). Examination revealed strong similarity among years in the percentage of stomachs which were empty (42 to 48%), the average degree of stomach fullness, and the prey spectrum. Small (< 20 cm) Greenland halibut preyed mainly on small crustaceans and cephalopods, medium-sized (20 to 69 cm) individuals preyed primarily on capelin ( Mallotus villosus), and large (> 69 cm) individuals preyed on a variety of demersal fish, particularly redfish ( Sebastes sp.) and Greenland halibut. An abrupt change in diet at about 64 to 69 cm was related to changes in both feeding habit and geographic distribution. The quantity of capelin in the stomachs was greatest on Hamilton Bank and on or near the coastal shelf off southern Labrador and northeastern Newfoundland. Medium-sized Greenland halibut were not highly aggregated in those areas where they were most successful in finding capelin. Preliminary estimates of daily and annual prey consumption indicate that Greenland halibut is an important predator of capelin.

ACID PRECIPITATION AND WEATHERING BY ORGANIC ACIDS IN LABRAI)OR LAKE BASINS1

ABSTRACT: Thirty‐five lakes in southern Labrador sampled in 1981 were resampled in 1989 and water chemistry values were compared between visits. Results showed higher pH, specific conductance, acid neutralization capacity, color, and base cations values in 1989, though sulfate, the ion most likely to reflect acid precipitation impacts, did not vary. The major ion changes measured were probably due to natural hydrological variations and not to changes in acid inputs.Results from the 1989 data showed a slight, but significant, decrease in water sulfate concentration trend from western to eastern Labrador, though most values, even in the western portion of the study area, fell close to the values considered “background” by Brakke et at. (1989). Base cation concentrations exceeded those which could be predicted from weathering by carbonic and bicarbonic acid. Assuming that little weathering is generated by acid precipitation in this region, the excess cations measured are probably a result of bedrock dissolution from organic acids generated by plant decomposition. Calculations showed that organic acid effect could be responsible for 9 to 52 percent of total weathering in the study basins.

A quantitative comparison of two paleomagnetic records of the Cobb Mountain Subchron from North Atlantic deep‐sea sediments

We present a new paleomagnetic record of the Cobb Mountain Subchron obtained from deep‐sea sediments cored at Ocean Drilling Program site 647 in the southern Labrador Sea. The details of the transitional field behavior documented by this record appear to be very similar to those recorded in a previously published record of this subchron obtained at Deep‐Sea Drilling Project (DSDP) site 609 in the North Atlantic (Clement and Kent, 1987). We used a quantitative correlation technique (Martinson et al., 1982) to establish statistically the degree of similarity between these two records and thereby constrain the spatial variability in these transitional fields. The error in the alignments is reduced significantly by aligning records of virtual geomagnetic pole positions rather than directions, indicating that these records document such large scale changes in the fields that we can not distinguish them from dipolar changes, given the proximity of these two sites. These replicate records of the Cobb Mountain Subchron provide evidence that deep‐sea sediments are capable of providing high resolution records of geomagnetic field behavior. A reexamination of the sequence of polarity transitions recorded at DSDP site 609 in light of these results suggests the presence of two preferred transitional field configurations. The field appears to change from one configuration to the other for several reversals and then back to the original configuration, suggesting that a geographical influence on the reversal process persists through this sequence. The variability in these reversal records provides insights into the response of the geodynamo to this geographical influence.

Archaeocyath palaeoecology

A well preserved archaeocyath fauna occurs in the Forteau Formation in Southern Labrador, Canada. Following on from the confirmation that archaeocyatha are aspiculate calcified sponges, detailed ecological work is now being undertaken on this fauna, a representative of the first reefal ecosystem in the fossil record.One species, Metaldetes profundus, shows considerable variability in growth form, from open bowl-shaped forms in lagoonal settings, to a branching morphology in biohermal habitats. This species also appears to colonise a variety of substrate types and for this purpose often uses exothecal structures and holdfasts. M. profundus is also the dominant species numerically, comprising 80% of the fauna, except at the top of the bioherm horizon, where Archaeocyathus atlanticus becomes dominant. In contrast to previous studies' findings, bowl-shaped Metaldetes at the top of the bioherm horizon occupy the basal region of the bioherms, not the upper areas and provide a surface on which the bioherms can develop.The unique form of Retilamina amourensis endows it with the ability to stabilise substrates so facilitating the colonization of a substrate. It is more common at the base of bioherms, providing a surface on which other archaeocyaths can settle. The calcimicrobes Renalcis and Epiphyton also appear to have played a major role in the initiation of the bioherms, occurring as 3–5cm thick layers on erosion surfaces, within which small, juvenile, upright M. profundus sticks, &lt;1cm in diameter, are found, surrounded and supported by the dense calcimicrobe aggregate.Digital 3-D analysis is being used to document the behaviour of the archaeocyaths, together with vertical and lateral zonation within the bioherms, especially with regard to the timing of calcimicrobe encrustation. Volumetric abundances of the archaeocyaths are also being calculated.There are small faunal composition changes over the area: Archaeosycon billingsi, a solitary stick-like form is more abundant in the west than in the east and Archaeocyathus atlanticus, another stick-like form occurs in dense clusters in lagoonal environments, elsewhere being solitary.

Decay of zooplankton patchiness generated at the sea surface

Population interaction in the sea depends on local population density, which can change rapidly under the influence of circulatory structures such as Langmuir cells generated by wind stress. We investigated variation in local density of gelatinous zooplankton at the sea surface during and after wind events in the southern Labrador Current. The first hypothesis we tested was that the onset of wind generates variation in local density of gelatinous zooplankton at the spatial scale of Langmuir circulation. Analysis of transects before and during a wind event showed no intensificati on of variability at small («10 m) scales. The second hypothesis was that spatial variation at the scale of Langmuir circulation decays during calm periods. Loss of significant components of variability was observed along the latter part relative to the earlier part of two transects. The third hypothesis we tested was that variability at larger spatial scales would exceed variability at smaller scales due to sweeping of small Langmuir cells into larger cells. We found that spatial variability increased with spatial scale along transects made during a wind event. Based on our observations we propose two hypotheses about the spatial structure of gelatinous zooplankton at the sea surface. The first is that the initial effect of a wind rising from a new direction is to rapidly erase structure generated by a previous wind. The second hypothesis is that Langmuir circulation generates variability at identical spatial scales over several kilometres, but that the magnitude of this variation is not uniform over these distances.