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Source-linked reports with geographic coverage including Canada, United States.

At least 1,207 records · Page 67Linked to original sources
USGS1989

Mélanges and olistostromes in the Appalachians of the United States and mainland Canada; An assessment

There is no completely accepted definition of a mélange, and the papers in this volume reflect this fact. In our regional assessment, the term mélange is principally used for a technically fragmented and mixed body of rock. A different term, olistostrome, is used for a chaotic and mixed rock body that formed by sedimentary processes such as slumping or gravity sliding. The term olistostromal mélange is used here if sedimentary processes and tectonic deformation were both involved in the fragmentation and mixing. In some cases there is evidence that these were effectively concurrent. Four main belts of Paleozoic mélanges and olistostromes have been recorded in the Appalachians of the northeastern United States and mainland Canada. These include: (1) olistostromes and olistostromal mélanges along Logan's line and the Taconic allochthons, which are related to thrusting during the Taconian orogeny; (2) mélanges associated with ophiolite fragments along the Baie Verte-Brompton line, which are thought to represent a Taconian suture; (3) mélanges containing ophiolite fragments along the Hurricane Mountain mélange belt (Boone and Boudette, this volume), which are thought to represent a Penobscottian terrane boundary; and (4) Acadian mélanges and olistostromes such as the Silurian Deadman Harbour mélange, an olistostromal mélange that probably formed at the front of an Acadian overthrust. In addition, Precambrian olistostromes have been recognized in southeastern New England and in the Green Head Formation of New Brunswick. These may have originated along normal faults on the rifted continental shelf of Gondwanaland, or they may relate to an earlier Pan-African cycle. These Precambrian olistostromes, therefore, accompany the extensional development of the Iapetus Ocean, whereas the Paleozoic olistostromes and mélanges mark its progressive closure. Five main sets of Paleozoic mélanges and olistostromes have been recorded in the central and southern Appalachians. These are: (1) a composite mélange-olistostrome belt in the Piedmont of Maryland and Virginia that includes olistostromes such as the Sykesville Formation (of unknown age) and mélanges such as those of the Morgan Run Formation (of debated age) and Mine Run Complex, some of which contain possible ophiolite fragments; (2) mélanges in the Blue Ridge Province from Virginia to Alabama, which contain possible ophiolite fragments; (3) Silurian or Early Devonian olistostromes of the Lay Dam Formation in the Talladega slate belt of Alabama; (4) mélanges, including the Falls Lake and Juliette mélanges in the Carolinas and Georgia, that border the Carolina terrane as defined by Secor and others (1983); and (5) broken formations and mélanges along major faults such as the Pulaski and Brevard, which are mostly related to Alleghanian thrusting. In addition, there is good evidence in the Ocoee Supergroup of the Blue Ridge Province for Late Proterozoic olistostromes related to the initiation of grabens prior to the opening of the Iapetus Ocean.

Alabama, Connecticut, Georgia, Kentucky, Maine, Ma↗
USGS1989

ROV dives under Great Lakes ice

Observations of the underside of ice have a wide variety of applications. Severe under-ice roughness can affect ice movements, rough under-ice surfaces can scour the bottom disturbing biota and man-made structures such as pipelines, and the flow rate of rivers is often affected by under-ice roughness. A few reported observations of the underside of an ice cover have been made, usually by cutting a large block of ice and overturning it, by extensive boring, or by remote sensing. Such operations are extremely labor-intensive and, in some cases, prone to inaccuracies. Remotely operated vehicles (ROV) can partially solve these problems. In this note, we describe the use, performance in a hostile environment, and results of a study in which a ROV was deployed under the ice in Lake Erie (North American Great Lakes).

Lake Erie↗
USGS1989

Kinky vitrinite reflectance well profiles: Evidence of paleopore pressure in low-permeability, gas-bearing sequences in Rocky Mountain foreland basins

Vitrinite reflectance (R m ) profiles of wells drilled in abnormally pressured, low-permeability gas-bearing sequences in Rocky Mountain foreland basins are commonly nonlinear with two or more nonparallel segments. These kinky profiles are most likely due to perturbations of the thermal gradient caused by contrasting heat transfer processes associated with the development of abnormally high pressures. We interpret the intersection of the shallow and intermediate R m segments to mark the approximate original boundary between normal-pressured, water-bearing rocks and underlying overpressured gas- and water-bearing rocks. The intersection of the intermediate and deep R m segments marks the approximate original boundary between overpressured gas- nd water-bearing rocks and underlying overpressured gas-bearing rocks. However, because overpressuring is a transient condition that eventually evolves into normal pressuring or underpressuring, these intersections may not coincide with the present top of abnormal pressuring. These segmented R m profiles occur in several Rocky Mountain basins of the United States and Canada.

Alberta, Colorado, Wyoming↗
USGS1989

Genetic differentiation among lake trout strains stocked into Lake Ontario

The lake trout Salvelinus namaycush is the focus of an international effort by fishery management agencies to restore this once‐native species to Lake Ontario. Evaluation of reproductive success and comparisons among stocked lake trout strains require genetic markers. We used allozyme variation to make genetic comparisons among strains of lake trout stocked into Lake Ontario. Forty‐two proteins presumed to be encoded by 102 loci were resolved electrophoretically; 18 loci were polymorphic. Among 16 samples from five principal origins (Finger Lakes, Great Lakes basin, northern New York–Adirondack, Manitoba, and mixed origins–Lake Ontario), the average observed heterozygosity was 0.029, and the proportion of polymorphic loci was 0.125. Significant differences occurred among the 16 samples at all 18 possible locus comparisons. The average F st value was 0.14. Hierarchical analysis indicated that the variation among samples within an origin was greatest within the Great Lakes basin, which included the greatest number of samples and represented the largest geographic area. Most variation observed among samples, however, occurred among origins. The 1983 and 1984 hatchery year classes produced from the 1978 Seneca brood stock did not differ significantly. The 1981 Seneca brood stock more closely resembled the sample of wild lake trout from Seneca Lake than progeny from the 1978 brood stock. The closer affinity of the 1981 brood stock to wild Seneca lake trout may be due to the larger number of wild adults from Seneca Lake used to found these fish than was used to establish the 1978 brood stock. Siscowet (“fat”) and “lean” lake trout from Lake Superior were significantly different from each other; however, the level of variation between them was not greater than that among samples from other origins, and thus did not support recognition of siscowet lake trout as a distinct subspecies. The Jenny Lake strain possessed a genetic affinity to the siscowet sample from Lake Superior. Historical reports about the origin of this strain suggest that siscowet lake trout from northern Lake Michigan may have been used to found this strain. Therefore, the Jenny Lake strain may serve as a gene source for the establishment of the siscowet lake trout in Lake Ontario. The substantial differentiation among lake trout strains reported here supports the feasibility of using allozyme markers to identify the parental sources of naturally produced young.

Lake Ontario↗
USGS1989

Mineral occurrence and drill-hole location map of the International Falls 1 degree by 2 degrees quadrangle, Minnesota and Ontario

A project to assess the mineral potential of the U.S. part of the International Fall 1° x 2° quadrangle was undertaken by the U.S. Geological Survey (USGS) in the early 1984, as part of the Conterminous United States Mineral Assessment Program (CUSMAP). Because glacial drift covers most of the basement rocks south of the U.S.-Canada border and mineral production in this part of Minnesota has been virtually nonexistent, data from the adjacent part of Ontario has been used to understand the geologic framework and to evaluate mineral-deposit models relevant to the assessment of the U.S. part of the International Falls quadrangle. This map and accompanying tables show the locations of mineral occurrences, prospects and mines in both Canada and the United States, and summarize their lithologic association and the characteristic metals found in them. Locations of drill holes within the United States and completed before 1987 are also included on the map.

Minnesota, Ontario↗
USGS1989

Ground-water flow and quality near the Upper Great Lakes connecting channels, Michigan

The Upper Great Lakes connecting channels are the St. Marys, St. Clair and Detroit Rivers, and Lake St. Clair. The effect of ground water on the connecting channels is largely unknown, and the controls on its movement and quality are undefined. Geologic, hydrologic, and environmental conditions near the channels have been examined.for this investigation. Included in the study area is a 50-mile reach of channel beginning at Whitefish Bay and extending to Neebish Island, and a 90-mile reach of channel between Port Huron and Pointe Mouillee in Lake Erie. Glacial deposits, which transmit most ground water to the channels, range from less than 100 feet in thickness in the southern part of the St. Clair-Detroit River area to more than 250 feet in thickness in the northern part. Marine seismic surveys were used at some locations to determine the thickness of deposits. Glacial deposits in the St. Marys River area range from less than 10 feet to more than 300 feet in thickness. Permeable bedrock in the southern reach of the Detroit River area and throughout most of the St. Marys River area may contribute substantial amounts of water to the channels. Total ground-water discharge to the channels, by area, is estimated as follows! St. Marys area, 76 cubic feet per second; St. Clair area, 11 cubic feet per second; Lake St. Clair area, 46 cubic feet per second; and Detroit area, 54 cubic feet per second. Analyses of water from 31 wells, 25 of which were installed by the U.S. Geological Survey, were made for organic compounds, trace metals, and other substances. Volatile hydrocarbons, and base neutral, acid extractable, and chlorinated neutral compounds were not detectable in water at most locations. Concentrations of trace metals, however, were higher than common in natural waters at some locations.

Michigan, Ontario↗
USGS1989

Trends in selected water-quality characteristics, Flathead River at Flathead, British Columbia, and at Columbia Falls, Montana, water years 1975-86

Data for selected water quality variables were evaluated for trends at two sampling stations--Flathead River at Flathead, British Columbia (Flathead station) and Flathead River at Columbia Falls, Montana (Columbia Falls station). The results were compared between stations. The analyses included data from water years 1975-86 at the Flathead station and water years 1979-86 at the Columbia Falls station. The seasonal Kendall test was applied to adjusted concentrations for variables related to discharge and to unadjusted concentrations for the remaining variables. Slope estimates were made for variables with significant trends unless data were reported as less than the detection limit. At the Flathead station, concentrations of dissolved solids, calcium, magnesium, sodium, dissolved nitrite plus nitrate nitrogen, ammonia nitrogen (total and dissolved), total organic nitrogen, and total phosphorus increased during the study period. Concentrations of total nitrite plus nitrate nitrogen and dissolved iron decreased during the same period. At the Columbia Falls station, concentrations increased for calcium and magnesium and decreased for sulfate and dissolved phosphorus. No trends were detected for 10 other variables tested at each station. Data for the Flathead station were reanalyzed for water years 1979-86. Trends in the data increased for magnesium and dissolved nitrite plus nitrate nitrogen and decreased for dissolved iron. Magnesium was the only variable that displayed a trend (increasing) at both stations. The increasing trends that were detected probably will not adversely affect the water quality of the Flathead River in the near future. (USGS)

British Columbia, Montana↗
USGS1988

Distribution patterns during winter and fidelity to wintering areas of American black ducks

The distribution patterns during winter of American black ducks ( Anas rubripes ) were compared among age – sex classes using band recovery data. In addition, fidelity to wintering areas was compared between sexes and between coastal and inland wintering sites. We did not find evidence of age- or sex-specific differences in distribution patterns ( P > 0.10). Black ducks exhibited a stronger fidelity to coastal wintering areas ( P < 0.01), but there were no sex-specific differences ( P > 0.30). We believe that the early formation of breeding pairs and possibly predictable food resources may reduce age – sex segregation in distribution patterns during winter. The predictability of food resources in coastal, as opposed to inland, wintering areas is likely responsible for the greater fidelity of black ducks to coastal wintering sites.

Delaware, Illinois, Labrador, Maine, Maryland, Mas↗
USGS1988

Distribution patterns of American black duck and mallard winter band recoveries

We compared the distribution patterns of winter band recoveries of American black ducks ( Anas rubripes ) and mallards ( A. platyrhynchos ) banded in the same breeding areas. Young black ducks wintered northeast of young mallards but no differences in distribution patterns were detected between adult birds of the 2 species. Mallards exhibited greater temporal variation in distribution patterns and less fidelity to wintering areas. We speculate that these differences in distribution patterns are related to different behavioral responses by mallards and black ducks to variation in resource availability. Black ducks may reduce energy expenditure during periods of extreme cold and wait for conditions to improve, whereas mallards may migrate to areas that are warmer of where more food is available. The availability of quality habitat may be critical to the survival of black ducks during harsh weather conditions because of their relative lack of migrational flexibility, whereas mallards may be able to respond by migrating to favorable environments.

Journal of Wildlife Management↗
USGS1988

The effects of hunting on survival rates of American black ducks

Using data from 10 preseason and 10 winter major reference areas from 1950-83, the authors tested hypotheses regarding the effects of hunting on the survival and recovery rates of the American black duck ( Anas rubripes ). Although estimates of the proportion of total annual mortality due to hunting are low (35% for ad and 45% for young) compared to Blandin's (1982) estimates, mean mortality and kill rates have increased since 1982. When hunting regulations were liberalized, recovery rates increased and survival rates decreased in males whereas only recovery rates increased in females. Changes in hunting regulations appeared to affect survival rates of adult males and young American black ducks.

Journal of Wildlife Management↗
USGS1988

Map and tabulation of quaternary mass movements along the United States-Canadian Atlantic continental slope from 32 degrees 00 minutes to 47 degrees 00 minutes N. latitude

Since the initial report on the Grand Banks Slump off southern Newfoundland (Heezen and Ewing, 1952), a large body of data on submarine mass movement along the Atlantic continental margin of the United States and Canada has been published. These data were compiled to provide this distribution map (sheet 1) and tabulation (sheet 2) of "principal facts" on mass movement of the northwest Atlantic Continental Slope. Although we prepared this inventory to facilitate our study of Quaternary mass movement along the U.S. Continental Slope, we judged the compilation to be large enough and detailed enough to be published as a generally useful data source and compendium. Sheet 3 shows examples of mass movement styles.

Atlantic Continental slope↗
USGS1988

Estimation, analysis, sources, and verification of consumptive water use data in the Great Lakes-St. Lawrence River basin

The Great Lakes-St. Lawrence River basin provides water for many uses and for wildlife habitat; thus many groups have developed strategies to manage the basin 's water resource. The International Joint Commission (IJC) is reviewing and comparing available consumptive-use data to assess the magnitude and effect of consumptive uses under present projected economic and hydraulic conditions on lake levels. As a part of this effort, the U.S. Geological Survey compared its own estimates of consumptive use in the United States with those generated by (1) the International Great Lakes Diversions and (2) the IJC. The U.S. Geological Survey also developed two methods of calculating consumptive-use projections for 1980 through 2000; one method yields an estimate of 6,490 cu ft/s for the year 2000; the other yields an estimate of 8,330 cu ft/s. These two projections could be considered the upper and lower limits for the year 2000. The reasons for the varying estimates are differences in (1) methods by which base year values were developed, and (2) the methods or models that were used to project consumptive-use values for the future. Acquisition of consumptive-use data from water users or governmental agencies or ministries would be desirable to minimize reliance on estimates.

Great Lakes-St. Lawrence River basin↗