Ice-proximal sediment accumulation rates in a temperate glacial fjord, southeastern Alaska

1991 ◽  
pp. 61-74 ◽  
Author(s):  
Ellen A. Cowan ◽  
Ross D. Powell
Keyword(s):  
Sediment Accumulation ◽  
Accumulation Rates

SEDIMENT ACCUMULATION RATES QUANTIFIED WITH COSMOGENIC NEON-21 ON A GLACIAL MORAINE, BLOODY CANYON, CA

2017 ◽  
Author(s):  
Daniel Morgan ◽  
◽  
Greg Balco ◽  
Alison Cribb ◽  
J. Warner Cribb ◽  
...  
Keyword(s):  
Sediment Accumulation ◽  
Accumulation Rates

The assessment of 210Pb data from sites with varying sediment accumulation rates

Hydrobiologia ◽  
1983 ◽  
Vol 103 (1) ◽  
pp. 29-35 ◽  
Author(s):  
P. G. Appleby ◽  
F. Oldfieldz
Keyword(s):  
Sediment Accumulation ◽  
Accumulation Rates

Linked variations in sediment accumulation rates and sea-level in Guanabara Bay, Brazil, over the last 6000years

2014 ◽  
Vol 415 ◽  
pp. 83-90 ◽  
Author(s):  
Alberto G. Figueiredo ◽  
Mauro B. de Toledo ◽  
Renato C. Cordeiro ◽  
José M.O. Godoy ◽  
Fabiano T. da Silva ◽  
...  
Keyword(s):  
Sea Level ◽  
Sediment Accumulation ◽  
Guanabara Bay ◽  
Accumulation Rates ◽  
And Sea Level

scholarly journals High-resolution magnetostratigraphy of the upper Nacimiento Formation, San Juan Basin, New Mexico, USA: implications for basin evolution and mammalian turnover

2017 ◽  
Author(s):  
Caitlin Leslie ◽  
Daniel J. Peppe ◽  
Thomas E. Williamson ◽  
Dario Bilardello ◽  
Matthew Heizler ◽  
...  
Keyword(s):  
New Mexico ◽  
North America ◽  
Accumulation Rate ◽  
Global Climate ◽  
Sediment Accumulation ◽  
San Juan ◽  
Accumulation Rates ◽  
Fluvial System ◽  
San Juan Basin ◽  
Geomagnetic Polarity

Lower Paleocene deposits in the San Juan Basin document one of the best records of mammalian change and turnover following the Cretaceous-Paleogene extinctions and are the type section for the Puercan (Pu) and Torrejonian (To) North America Land Mammal age biozones (NALMA). One of the largest mammalian turnover events in the early Paleocene occurs between the Torrejonian 2 (To2) and Torrejonian 3 (To3) NALMA biozones. The Nacimiento Formation are the only deposits in North America where the To2-To3 mammalian turnover can be constrained, however the precise age and duration of the turnover is poorly understood due to the lack of a precise chronostratigraphic framework. We analyzed paleomagnetic samples, produced a 40Ar/39Ar detrital sanidine age, and developed a detailed lithostratigraphy for four sections of the upper Nacimiento Formation in the San Juan Basin, New Mexico (Kutz Canyon, Escavada Wash, Torreon West and East) to constrain the age and duration of the deposits and the To2-To3 turnover. The polarity stratigraphy for the four sections can be correlated to chrons C27r-C26r of the geomagnetic polarity time scale (GPTS). Using the local polarity stratigraphy for each section, we calculated a mean sediment accumulation rate and developed a precise age model, which allows us to determine the age of important late Torrejonian mammalian localities. Using the assigned ages, we estimate the To2-To3 turnover was relatively rapid and occurred over ~120 kyr (-60/+50 kyr) between 62.59 and 62.47 Ma. This rapid duration of the mammalian turnover suggests that it was driven by external forcing factors, such as environmental change driven by the progradation of the distributive fluvial system across the basin and/or changes in regional or global climate. Additionally, comparisons of the mean sediment accumulation rates between the sections that span from the basin margin to the basin center indicate that sediment accumulation rates equalized across the basin from the end of C27r through the start of C26r, suggesting an accommodation minima in the basin associated with the progradation of a distributive fluvial system into the basin. This accommodation minimum also likely led to the long hiatus of deposition between the Paleocene Nacimiento Formation and the overlying Eocene San Jose Formation.

scholarly journals 240+239Pu depositional signatures as a viable geochronological tool in the Amazon Basin

2017 ◽  
Vol 44 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Luciana M Sanders ◽  
Kathryn H Taffs ◽  
Debra Stokes ◽  
Alex Enrich-Prast ◽  
Christian J Sanders
Keyword(s):  
Amazon Basin ◽  
Environmental Science ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Recent Sediment ◽  
Floodplain Lake ◽  
Accumulation Rates ◽  
Amazon Floodplain ◽  
Dating Methods ◽  
Lead 210

AbstractAnthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20thcentury. The240Pu +239Pu (240+239Pu) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year-1), Tapajos (10.2 and 2.4 mm year-1) and Madeira (3.4, 4.2 and 6.2 mm year-1). The results from this study show that240+239Pu fallout activities, and the well documented (240Pu/239Pu) atomic ratios of the above ground nuclear tests which began in the 1950’s, are sufficient and well preserved in Amazon floodplain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the240+239Pu and210Pb dating methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20thcentury. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous ~60 years) along the Amazon Basin.

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