Canada ; Cold area ; Comparative study ; Coresampling ; Freezing ; Gaspé ; Quebec ; Research technique ; River bed ; Sampling ; Statistical bias
The aims of this paper are to quantify the relative biases of the freeze-core and bulk sampling techniques against more accurate composite samples and to examine whether systematic losses of fines can be predicted. At 6 riffles the spawning
substrate was sampled under approximately 50 cm of water with a bulk sample and 3 adjacent freeze-cores. For each riffle, data from the 2 samples were combined using the method of Fripp and Diplas (1993) and the resultant composite sample was compared
with the original freeze-core and bulk samples to assess the relative precision and biases of the 2 techniques.
A hand-held coresampler for plastic benthic sediments
Australia ; Coresampling ; Lacustrine sediment ; Lake ; Methodology ; Sedimentology ; Victoria
the corer to sample plastic sediments whithout compressing and distorting the core. The device was used successfully to take cores from the bottom of Lake Wellington, Gippsland, Victoria.
The sampler is based on the previous design of Miller and Bingham (1987) but incorporates two important modifications. The first prevents detachment and possible loss of the piston's sealing plug. The second is a support frame which enables
Sedimentary facies of borehole cores from the Mekong River floodplain in Cambodia
C 14 dating ; Cambodia ; Coresampling ; Delta ; Floodplain ; Holocene ; Quaternary ; Sedimentology
This study analyzes 3 borehole cores to examine the sedimentary facies of the extensive floodplain of the Mekong River in Cambodia and discusses the relationship between sedimentary facies and surface topography.
The aspect and opinion on the geology and paleogeography of the southeastern Great Plain were established as a result of the elaboration and sedimentological investigation of about 10000 coresamples. In addition to the structural and textural
features of the rock samples the structural situation within the Pannonian Basin as well as certain geochemical peculiarities on paleogeomorphological relations were also taken into consideration. (CK).
Climatic oscillations 10,000-155,000 yr B.P. at Owens Lake, California reflected in glacial rock flour abundance and lake salinity in core OL-92
California ; Carbonate ; Clay mineral ; Climatic variation ; Coresampling ; Geochemistry ; Glacier advance ; Lacustrine sediment ; Lake ; Quaternary ; Salinity ; United States of America
Chemical analyses of the acid-soluble and clay-size fractions of sediment samples (1500-yr resolution) reveal oscillations of lake salinity and of glacial advances in core OL-92 back to 155,000 yr B.P. The AA. found that the mineralogy and chemistry
A fast procedure for sampling sedimentary structures down to 1,1m in unconsolidated wet sands
An inexpensive, simple and efficient method has been developed for sampling sedimentary structures, down to 1.1m below the sediment surface, in unconsolidated wet sands. The method can be used on land and in quiet water to a depth of at least
4meters. The procedure makes possible the study of sedimentary structures in the form of lacquer peels measuring 1.1m. high and 0.1m. wide within one hour after coring has been started. (AIS).
X-ray radiographic analyses of sediment cores from the Cachi reservoir
Results and discussion. The radiographs of sampled sediment cores represent valuable documents for future studies of growing sedimentary sequences in the Cachí reservoir.
Arid area ; Botswana ; Calcrete ; Coresampling ; Geochemistry ; Geophysics ; Kalahari ; Lake ; Lake level ; Palaeo-environment ; Quaternary ; Sedimentology ; Silicrete
This paper reports the results of the analyses of 3 cores, 1.8 to 2.6 m in length, taken from Lebatse Pan in southeast Kalahari. The sedimentary characteristics are compared with other core logs from the region, and an assessment is made
Canada ; Cold area ; Coresampling ; Ice ; Periglacial features ; Permafrost ; Quebec ; Research technique ; Soil
This technique note presents a light drill specially designed for coring in permafrost. The drill was improved over several years at Université Laval's Centre d'études nordiques. This equipment allows total-length recovery of cores 10 cm in diameter
AMS-14C ages measured in deep sea cores from the Southern Ocean : implications for sedimentation rates during isotope stage 2
C14 dates obtained by accelerator mass spectrometry (AMS) on monospecific foraminiferal samples from two deep-sea sediment cores raised in the Indian sector of the southern Ocean have been corrected for the difference in C14 composition between
atmosphere and sea surface by using a reconstruction of the latitudinal C14 gradient which existed in the Southern Ocean prior to 1962. The corrected AMS-C14 data show a reduced sedimentation rates in core MD 84-527 between 25,000 and 10,000 yr B.P. For core
Use of floodplain sediment cores to investigate recent historical changes in overbank sedimentation rates and sediment sources in the catchment of the River Ouse, Yorkshire, UK
Coresampling ; England ; Floodplain ; Geochemistry ; Land use ; Sediment budget ; Sedimentation ; Sedimentology ; Suspended load ; Tracer ; United Kingdom ; Watershed ; Yorkshire
This paper reports the use of sediment cores collected from river floodplains to provide information on changing suspended sediment sources and sedimentation rates at 7 sites within the non-tidal component of the catchment of the River Ouse, and one
Pollen, foraminifer, dinocyst, and coarse lithic high-resolution analyses and δO 18 measurements have been carried out for the last glacial section of marine core MD95-2042 located near the southwestern margin of the Iberian Peninsula. The pollen
data indicate a high frequency of vegetational changes on the adjacent continent during this period, suggesting a climatic variability very similar to that of the Dansgaard-Oeschger cycles recorded by the Greenland ice cores. The detailed direct
correlation of the terrestrial and marine proxy data from core MD95-2042 indicates a three-phase pattern of Heinrich events in land and ocean environments.
The AA. present the results of an investigation of the ice-rafted debris (IRD) record in 2 suites of sediment cores from the continental rise west of the Antarctic Peninsula and the northern Weddell and Scotia Seas. The objectives are to investigate
whether the cores contain IRD layers that are sedimentologically similar to the Heinrich layers of the North Atlantic and to discuss implications for the Quaternary dynamics of the Antarctic Ice Sheet. The locations of the cores are appropriate
mining deposits, (3) geological mapping of the ocean floor and (4) petroleum exploration. Within these four major areas, variables are considered that influence the rationale for selection of a particular rig. Selection criteria include sampling, coring
Four categories of drilling and sampling application are discussed: (1) engineering-geological investigations to assess the foundation conditions for large offshore structures, (2) mineral exploration to determine the economic value of potential
Two major meltwater events are documented in cores from the NW Labrador Sea. These meltwater events coincide with Heinrich (H) layers 1 and 2 from North Atlantic sediments. The AA. hypothesize that δ18O records from these sites close to the former
Coresampling of a Holocene marine sedimentary sequence and underlying Neolithic cultural material off Franchthi Cave, Greece in Quaternary coastlines and marine archaeology: Towards the prehistory of land bridges and continental shelves.
Paleomagnetic analysis of samples from the original 600-m-long core from the San Agustin Plains, New Mexico, showed an unquestionable reversal stratigraphy dating the record back to at least 1.6 my. Analysis of pollen, ostracodes, and algae
of a duplicate sample section in the vicinity of the original coring site and spanning the last 18.000 yr B.P. shows a much higher resolution than the earlier results.
Andes ; Biogeography ; High mountain ; Ice core ; Ice sheet ; Palynology ; Peru ; Tropical zone
This study attempts to utilize 15 surface snow samples, taken on the Quelccaya Ice Cap, southern Peru, in late August of 2000, to help answer some basic questions of pollen dispersal and deposition on tropical Andean ice caps.