Taphonomy and paleoecology of the bivalve trace fossil Protovirgularia in deltaic heterolithic facies of the Miocene Chenque Formation, Patagonia, Argentina

2010 ◽  
Vol 84 (4) ◽  
pp. 730-738 ◽  
Author(s):  
Noelia B. Carmona ◽  
María Gabriela Mángano ◽  
Luis A. Buatois ◽  
Juan José Ponce
Keyword(s):  
Sedimentation Rate ◽  
Oxygen Depletion ◽  
Sedimentation Rates ◽  
Low Friction ◽  
Delta Front ◽  
Plastic Substrates ◽  
Marine Deposits ◽  
Median Axis ◽  
Nearshore Environments ◽  
Biogenic Structures

Lower Miocene tide-influenced deltaic deposits from the Chenque Formation, Patagonia, Argentina, contain abundant and well-preserved biogenic structures attributed to locomotion of deposit-feeder protobranch bivalves. These trace fossils, assigned to the ichnogenus Protovirgularia, consist of delicate, inclined-to-horizontal, chevronate structures, mostly symmetrical with respect to a median axis. Identification of Protovirgularia at sandstone sole beds (hypichnion) is quite straightforward. Endichnial, exichnial and epichnial preservation in heterolithic facies, however, provides a wide variety of forms that depart from the archetypal Protovirgularia and challenges ichnotaxonomic classification. Specimens in prodelta and delta-front facies display morphologic features controlled by substrate fluidity, toponomy, and sedimentation rate. Most specimens show sharp, closely spaced chevrons and occur along sandstone/mudstone interfaces of the proximal prodelta and distal delta-front deposits. These forms reflect how tracemakers experienced significant friction while advancing through the sediment, which resulted in relatively smaller increments of movements. In contrast, variants of Protovirgularia formed in muddier beds, such as in prodeltaic facies, show irregular, poorly defined and unevenly spaced chevrons, and are locally asymmetric in relation to the axis, reflecting softer, water-rich, and plastic substrates. This sediment offered relatively low friction but poor anchorage for the foot. These occurrences of Protovirgularia in tide-influenced, marginal-marine deposits suggests that protobranchs were tolerant of fluctuations in salinity, sedimentation rates, turbidity, and oxygen depletion, displaying opportunistic strategies in stressed nearshore environments. Our evaluation of taphonomic controls and appropriate identification of Protovirgularia can provide valuable information for expanding our knowledge of the ethology and paleoecology of protobranch bivalves.

The determination of sedimentation rates in Lake Ontario using the 210Pb dating method

1978 ◽  
Vol 15 (3) ◽  
pp. 431-437 ◽  
Author(s):  
John G. Farmer
Keyword(s):  
Sedimentation Rate ◽  
Lake Ontario ◽  
Sedimentary Basins ◽  
210Pb Dating ◽  
Sedimentation Rates ◽  
Surface Mixing ◽  
Dating Method ◽  
210Pb Dating Method

The 210Pb dating method has been applied successfully to the determination of recent sedimentation rates at four sites distributed among the three major sedimentary basins (Niagara, Mississauga and Rochester) of Lake Ontario. Following correction for effects due to compaction of the sediments, mean sedimentation rates ranging from 0.02 cm/year at the periphery of the Mississauga basin to 0.11 cm/year in the Niagara and Rochester basins were determined. Allowance for compaction reduced the non-compaction-corrected sedimentation rates by 20–35%. Neither 210Pb nor fallout 137Cs profiles indicated surface mixing of sediment sufficient to noticeably affect the calculated sedimentation rates. At all four sites, the sedimentation rate seems to have remained constant during the last 100–150 years.

scholarly journals Palaeoenvironmental reconstruction of Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland

2012 ◽  
Vol 62 (3) ◽  
pp. 463-484 ◽  
Author(s):  
Przemysław Gedl ◽  
Andrzej Kaim ◽  
Paulina Leonowicz ◽  
Andrzej Boczarowski ◽  
Teresa Dudek ◽  
...  
Keyword(s):  
Sea Level ◽  
Sedimentation Rate ◽  
Middle Jurassic ◽  
Oxygen Depletion ◽  
Living Conditions ◽  
Photic Zone ◽  
Phytoplankton Assemblages ◽  
Palaeoenvironmental Reconstruction ◽  
Sea Level Fluctuations ◽  
Organic Particles

ABSTRACT Gedl, P., Kaim, A., Leonowicz, P., Boczarowski, A., Dudek, T., Kędzierski, M., Rees, J., Smoleń, J., Szczepanik, P., Sztajner, P., Witkowska, M. and Ziaja, J. 2012. Palaeoenvironmental reconstruction of Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Krakow-Silesia Homocline, Poland. Acta Geologica Polonica, 62(3), 463-484. Warszawa. Multidisciplinary studies of the Middle-Upper Bathonian ore-bearing clays at Gnaszyn revealed variable palaeoenvironmental conditions during the deposition of this seemingly monotonous sequence. We interpret the conditions in the bottom environment and the photic zone, and also evaluate the influence of the adjacent land areas, based on sedimentology, geochemistry, sporomorphs and palynofacies composition, benthic (foraminifera, gastropods, bivalves, scaphopods, echinoderms), planktonic (calcareous nannoplankton, dinoflagellate cysts), and nektonic (sharks) fossils. The Gnaszyn succession originated relatively close to the shore, within reach of an intense supply of terrestrial fine clastic and organic particles. The latter are mainly of terrestrial origin and range from 1.5 to 2.5 wt.%. The precise water depth is difficult to estimate but most likely ranges from several tens of metres to a few hundred metres. All fossil groups show minor changes throughout the succession. As the climate seems to have been quite stable during this period we consider sea-level fluctuations to have been the main factor responsible for the changes. The terrestrial input, including freshwater and land-derived clastic and organic particles (sporomorphs and cuticles), increased during periods of sea-level lowstand. As a consequence, stress conditions (lower salinity, higher nutrient availability, lower water transparency) in the photic zone caused blooms of opportunistic planktonic taxa. Furthermore, a faster sedimentation rate led to oxygen depletion and deterioration of the living conditions in the bottom environment due to an increased accumulation of organic matter. As a result, the benthic biota became taxonomically impoverished and commonly dominated by juvenile forms. During periods of high sea level, the source areas were shifted away from the basin, resulting in a decrease in the terrestrial influx, increase in the salinity of surface waters, the appearance of more diverse phytoplankton assemblages, a lower sedimentation rate, and an improvement of living conditions at the bottom.

scholarly journals Lithium carbonate sedimentation using flocculants with different ionic bases

2021 ◽  
pp. 20-20
Author(s):  
Yam Morales ◽  
Nelson Herrera ◽  
Kevin Pérez
Keyword(s):  
Sedimentation Rate ◽  
Rapid Growth ◽  
Crystallization Process ◽  
Lithium Carbonate ◽  
Rechargeable Batteries ◽  
Point Of View ◽  
Sedimentation Rates ◽  
Economic Point ◽  
Carbonate Sedimentation ◽  
Cationic Flocculant

Lithium has become a metal of enormous interest worldwide. The extensive use of rechargeable batteries for a range of applications has pushed for rapid growth in demand for lithium carbonate. This compound is produced by crystallization, by reaction with lithium chloride (in solution) and by adding sodium carbonate. Low sedimentation rates in the evaporation pools present a problem in the crystallization process. For this reason, in this work, mineral sedimentation tests were carried out with the use of two flocculant types with different ionic charges. The tests were carried out at a laboratory level using different dosages for each flocculant and measurements were performed to obtain the increase in the content of solids in the sediment. The anionic flocculant had better performance as compared to that of the cationic flocculant, increasing the sedimentation rate of lithium carbonate by up to 6.5. However, similar solids contents were obtained with the use of the cationic flocculant at 3.5 times lower dosage making it the flocculant of choice regarding the economic point of view.

Late Quaternary history of the Lake O'Hara region, British Columbia – an evaluation of sedimentation rates and bulk amino acid ratios in lacustrine records

1988 ◽  
Vol 25 (7) ◽  
pp. 1037-1048 ◽  
Author(s):  
Mel A. Reasoner ◽  
Nathaniel W. Rutter
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Sedimentation Rate ◽  
River Sediments ◽  
Sedimentation Rates ◽  
Rate Data ◽  
Radiocarbon Dates ◽  
Clastic Sediments ◽  
Lake Cores ◽  
Total Sedimentation

Lake O'Hara (subalpine) and Opabin Lake (alpine) are situated directly adjacent to a high section of the Continental Divide in the central Canadian Rocky Mountains. Core samples recovered from the lakes show a consistent stratigraphy comprising gyttja and underlying inorganic clastic sediments. The gyttja contains Bridge River (2350 years BP) and Mazama (6800 years BP) tephras and is separated from the lower clastic sediments by a sharp, conformable contact. Radiocarbon dates obtained from conifer needles, extracted from directly above the contact, indicate that deglaciation had proceeded upvalley from the O'Hara basin priorto ca. 10 100 years BP. Preliminary palaeobotanical and macrofossil data suggest that a Pinus–Abies forest with lesser Picea was established in the vicinity of Lake O'Hara by this time. Consequently, the minimum age of moraine systems situated downvalley from Lake O'Hara is Late Wisconsinan.Mean annual sedimentation rates were derived from sediment thickness data from 14 Lake O'Hara and 2 Opabin Lake cores. Averaged total sedimentation rate values from the Lake O'Hara cores are 0.13 mm/year (post-Bridge River), 0.13 mm/year (Mazama – Bridge River) and 0.05 mm/year (11 000 years BP – Mazama). Averaged total sedimentation rate values from the Opabin Lake cores are 0.19 mm/year (post-Bridge River), 0.07 mm/year (Mazama – Bridge River), and 0.06 mm/year (8530 years BP – Mazama). Higher total sedimentation rates in post-Bridge River sediments of Opabin Lake are presumably related to climatic conditions associated with more extensive upvalley ice during the last ca. 2300 years. Highly variable sedimentation rate data obtained from the Lake O'Hara cores suggest that the use of sedimentation rate data as a proxy record of upvalley glacial activity is inappropriate in the Lake O'Hara setting where inflowing glacial stream systems are interrupted by upvalley lake basins.Aspartic acid D/L ratios were derived from bulk gyttja samples of known age from seven Lake O'Hara and one Opabin Lake core. In all but two cases, aspartic acid D/L ratios increase consistently with respect to sediment age. The increasing downcore trends in the aspartic acid D/L ratios suggest the possibility of using amino acid data from bulk gyttja samples as a check for reworking in cases where chronostratigraphic markers are absent.

scholarly journals Value of combining the erythrocyte sedimentation rate test with tuberculin testing in the control of tuberculosis in baboons

1976 ◽  
Vol 10 (1) ◽  
pp. 39-46 ◽  
Author(s):  
G. W. Tribe ◽  
A. E. Welburn
Keyword(s):  
Sedimentation Rate ◽  
Sedimentation Rates ◽  
Good Physical Condition ◽  
Erythrocyte Sedimentation ◽  
Rate Test ◽  
Tuberculin Testing ◽  
Further Development ◽  
Bovine Tuberculin ◽  
Erythrocyte Sedimentation Rates ◽  
Tuberculin Tests

2 batches of baboon infected with tuberculosis were subjected to serial tests with human and bovine tuberculin, while erythrocyte sedimentation rates were estimated concurrently. In the very early stages most but not all reacted to human tuberculin while fewer responded to bovine material. After further development of the disease, tuberculin tests remained positive while sedimentation rates were raised by 10-30 mm per hour. By the time early spread had occurred response to tuberculin was absent but sedimentation rates tended to increase. Advanced cases were always tuberculin negative but sedimentation rates were in excess of 50 mm per hour. Such animals were always in good physical condition and represented an insidious danger to other animals and staff in contact with them. Clinical examination failed to reveal cases of tuberculosis except in the terminal stages and no cases were diagnosed by radiography. 2 animals died from apparent anaphylaxis following inoculation of both types of tuberculin. Results showed that use of one or other of these tests alone would not have made possible the elimination of infection.

Halokinetic modulation of sedimentary systems: an integrated approach

2020 ◽  
Author(s):  
Zoe Cumberpatch ◽  
Emma Finch ◽  
Ian Kane ◽  
Christopher Jackson ◽  
David Hodgson ◽  
...  
Keyword(s):  
Sedimentation Rate ◽  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Sedimentary Basins ◽  
Integrated Approach ◽  
Discrete Element Modelling ◽  
Sedimentation Rates ◽  
Sediment Routing ◽  
And Storage ◽  
Sediment Interface

<p>Complicated structural-stratigraphic traps at the salt-sediment interface have historically hosted large hydrocarbon discoveries. Understanding sediment-routing around active salt bodies, is now vital for carbon capture and storage projects due to salt being a ‘near-perfect’ seal. Despite advances in subsurface visualisation, the salt-sediment interface remains difficult to image due to steep-bedding, bed-thickness changes and lithological contrasts. Outcropping examples provide depositional facies understanding, but are limited, largely due to the dissolution of associated halites. Studied analogues represent specific sedimentation rates and salt rise rates, which are difficult to accurately constrain and decipher.</p><p>Discrete Element Modelling (DEM) provides an efficient and inexpensive tool to analyse how depositional architectures around salt structures vary with sedimentation rate. Model input parameters are taken from the Bakio diapir, Basque Cantabrian Basin and the Pierce diapirs, eastern Central Graben and their adjacent, halokinetically influenced stratigraphic successions.</p><p>Six experiments were run, lasting for a total of 4.6 Myr. After a 2.2 Myr calibration period sediment was added to the model over three 800,000 year stages: 1) 2.2-3 Myr, 2) 3-3.8 Myr 3) 3.8-4.6 Myr. Sedimentation rate was varied to study the effects of sedimentation on mini-basin individualisation and extent of halokinetic modulation. The six experiments represent: no sedimentation, slow, intermediate and fast sediment input, increasing sedimentation and decreasing sedimentation. Outputs are validated by comparison to subsurface and outcropping examples globally.</p><p>Results show that: <br>1) Diapir growth is increased with some sedimentation, compared to no sedimentation, in agreement with models of passive diapirism by sediment loading, however growth is inhibited by increasing sedimentation rate.<br>2) Salt withdrawal mini-basins of 4-5 diapir-widths are formed and are controlled by the width of the diapir; outside of this, the overburden is undeformed. <br>3) Strata, at least initially, onlap and thin towards the topographic high created by the diapir.<br>4) Slow aggradation results in rotation of onlaps and sedimentation being restricted to mini-basins, making individualisation more probable, while sedimentation on the diapir roof eventually occurs in all other experiments.</p><p>5) Under high sedimentation rates, halokinetic influences on stratigraphy are ‘buried’ quicker, which could make the upper part of the syn-kinematic sequence difficult to decipher from the post-kinematic sequence.</p><p>The increasing sedimentation scenario simulates progradation, and is integrated with findings from the halokinetically-influenced successions around the Bakio (N.Spain) and Pierce (UK North Sea) diapirs. At Bakio, stratigraphy deposited above the diapir was removed by Pyrenean inversion. Incorporating outcrop-based sedimentary facies analysis with numerical modelling indicates that deposits experience facies changes towards stratigraphic pinch outs, mass failures could be common closest to diapirs and allows for the development of ‘zones’ of variably severe halokinetic influence. Combining Pierce core data and model results highlights a trade-off between reservoir quality and stratigraphic trap integrity that may aid development of hydrocarbon fields and carbon capture and storage sites in salt-bearing sedimentary basins.</p><p>Our innovative, iterative, integrated approach is capable of improving understanding of the variables influencing sediment-routing and stratigraphic trap configuration around extensional-passive diapirs, and can be applied to a multitude of depositional settings.</p>

AMS-14C Ages Measured in Deep Sea Cores from the Southern Ocean: Implications for Sedimentation Rates during Isotope Stage 2

1989 ◽  
Vol 31 (2) ◽  
pp. 309-317 ◽  
Author(s):  
Edouard Bard ◽  
Laurent Labeyrie ◽  
Maurice Arnold ◽  
Monique Labracherie ◽  
Jean-Jacques Pichon ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sedimentation Rate ◽  
Deep Sea ◽  
Sediment Cores ◽  
Sea Surface ◽  
Sedimentation Rates ◽  
Deep Sea Sediment ◽  
The Difference ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract14C 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 14C composition between atmosphere and sea surface by using a reconstruction of the latitudinal 14C gradient which existed in the Southern Ocean prior to 1962. The corrected AMS-14C data show a reduced sedimentation rate in core MD 84-527 between 25,000 and 10,000 yr BP. For core MD 84-551 the available data suggest that the sedimentation rate was higher during the Holocene than during the glacial period. These changes in sedimentation rates may be attributed to an increased opal dissolution during the last glacial maximum.

Dominant Factors Influencing Overall Temporal Sedimentation Rates at Loagan Bunut Lake, Miri, Sarawak, Malaysia.

2011 ◽  
Vol 356-360 ◽  
pp. 2406-2415 ◽  
Author(s):  
R.B. Dagang ◽  
S. Lau ◽  
A.K. Sayok
Keyword(s):  
Suspended Sediment ◽  
Sedimentation Rate ◽  
Settling Velocity ◽  
Flood Plain ◽  
Water Volume ◽  
Sedimentation Rates ◽  
Sediment Distribution ◽  
Factors Influencing ◽  
Physical Changes ◽  
Best Fit

This paper is to predict dominant factors influencing temporal sedimentation rates at Loagan Bunut Lake using best-fit model of sedimentation rate and distance from Bunut River. The lake is a flood plain lake located in Sarawak, Malaysia. Twenty two cylindrical traps were installed at the lake from November 2005 until April 2008. Each sample was collected after about four to five months of deployment. Dry sedimentation rates from the traps and the linear distances from Trap 1 located at the confluence of Bunut River were measured. The factors that influence the temporal sedimentation at the lake were both internal and external physical changes of the lake. The factors were net ws (net Stoke’s settling velocity) and water volume in the lake for suspended sediment distribution.

scholarly journals Sedimentation rates (data on 210pb and 137cs radionuclides) in different facial-genetic types of the Kara sea bottom sediments

2019 ◽  
Vol 64 (11) ◽  
pp. 1158-1174
Author(s):  
V. Yu. Rusakov ◽  
A. P. Borisov ◽  
G. Yu. Solovieva
Keyword(s):  
Bottom Sediments ◽  
Sedimentation Rate ◽  
Isotope Composition ◽  
Original Data ◽  
Kara Sea ◽  
Sedimentation Rates ◽  
Shallow Marine ◽  
Novaya Zemlya ◽  
Genetic Types ◽  
Sea Bottom

In the article original data on isotope composition of natural excess Pb-210 and artificial Cs-137 radionuclides in upper 2550-cm layer of sea-bottom sediments at the Kara Sea (from Ob and Yenisei estuaries, Eastern-Novaya-Zemlya trough, Voronin trough, as well as Sedov bay (Novaya Zemlya)) are presented. The research results showed close tie between sedimentation rates and facial-genetic types of the sea-bottom sediments. Highest sedimentation rates are typical for the terrigenic-estuarine type. The type is divided on tractional load with sedimentation rate 0.40.7 cm per year and mud bank sediments with sedimentation rate 0.71.0 cm per year. The terrigenic-shallow-marine type is characterized by lowest sedimentation rate 0.10.3 cm per year. The background terrigenic-marine type has a broadest spectrum of the sedimentation rates: on trough slope the rates are minimal (likely to terrigenic-shallow-marine type), within central parts of the trough (as a result of gravity creep) the rates may increase up to 0.9 cm per year. Single facial-genetic type is glacial sediments of Navaya Zemlya bays. Measured recent sedimentation rate within inner depression of the Sedov bay is 0.10.2 cm per year.

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