Ichnofabrics Elucidate the Accumulation History of a Condensed Interval Containing a Vertically Emplaced Ichthyosaur Skull

2007 ◽  
Author(s):  
Andreas Wetzel ◽  
Achim G. Reisdorf
Keyword(s):  
History Of ◽  
Accumulation History

Chronology and dust mass accumulation history of the Wenchuan loess on eastern Tibetan Plateau since the last glacial

2021 ◽  
Vol 53 ◽  
pp. 100748
Author(s):  
Li Liu ◽  
Shengli Yang ◽  
Ting Cheng ◽  
Xiaojing Liu ◽  
Yuanlong Luo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
Last Glacial ◽  
Dust Mass ◽  
History Of ◽  
Mass Accumulation ◽  
The Last Glacial ◽  
Accumulation History

Accumulation History of Uranium in Boulders - New Support for Postglacial Matrix Diffusion

1997 ◽  
Vol 506 ◽  
Author(s):  
Kari Rasilainen ◽  
Juhani Suksi ◽  
Antero Lindberg
Keyword(s):  
Time Scale ◽  
Early Stage ◽  
Matrix Diffusion ◽  
Natural Analogue ◽  
Land Uplift ◽  
Decay Stage ◽  
History Of ◽  
End Stage ◽  
Chain Decay ◽  
Accumulation History

Extended AbstractGeological formations are being considered as host media for nuclear waste disposal. The occurrence of natural U in rocks provides a possibility to test the radionuclide migration models used in safety studies of the disposal over comparable time periods. Here we study U accumulation into boulders as a process analogue for matrix diffusion; the boulders were found in glacial till in Hämeenlinna, southern Finland. Based on the glacial history of the site, matrix diffusion simulations, and independent U-series disequilibria (USD) dating, the U accumulation was interpreted to originate from the end stage of the latest glaciation, i.e. the system age is about 10 000 years1,2. The known time scale offers a rare opportunity for quantitative model testing; normally the time scale is difficult to determine for a single process in a natural analogue.The U accumulation was earlier1,2 interpreted to be due to matrix diffusion and sorption. The postulated accumulation history consists of short in-diffusion and out-diffusion stages, as well as a longer chain decay stage. The in-diffusion was caused by U-rich waters discharging on the boulders at the end stage of the glaciation. The subsequent partial out-diffusion represents the period the boulders were temporarily submerged in the Yoldia sea during the early stage of the Baltic Sea. The final isolated radioactive chain decay stage began when the boulders, and their surroundings, rose above the sea level due to land uplift.In this paper we report the first radiochemical results of a new larger boulder from the same area as the one studied earlier1; qualitatively, also the U distribution appears to be the same. Due to the larger dimensions, we can sample the inner zone of the boulder which matrix diffusion can not have reached within the postulated time, i.e. the state of the boulder before the U accumulation. The large amount of sample material containing almost only the recently accumulated U provides an opportunity to experimentally approach the kinetics of U fixation in situ. Understanding the long-term U fixation is essential in natural analogue studies, because the matrix diffusion model only has fast reversible adsorption (based on Kd) as the fixation process. Attempts to separate and quantify sorbed U in natural analogues have been reported elsewhere3.

scholarly journals Reconstructing the accumulation history of a saltmarsh sediment core: Which age-depth model is best?

2017 ◽  
Vol 39 ◽  
pp. 35-67 ◽  
Author(s):  
Alexander J. Wright ◽  
Robin J. Edwards ◽  
Orson van de Plassche ◽  
Maarten Blaauw ◽  
Andrew C. Parnell ◽  
...  
Keyword(s):  
Sediment Core ◽  
History Of ◽  
Accumulation History

scholarly journals Inferring paleo-accumulation records from ice-core data by an adjoint method: application to James Ross Island's ice core

2014 ◽  
Vol 10 (5) ◽  
pp. 3821-3845 ◽  
Author(s):  
C. Martín ◽  
R. Mulvaney ◽  
G. H. Gudmundsson ◽  
H. Corr
Keyword(s):  
Vertical Velocity ◽  
Adjoint Method ◽  
Ice Core ◽  
Synthetic Data ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Polar Regions ◽  
History Of ◽  
Climatic Record ◽  
Accumulation History

Abstract. Ice cores contain a record of snow precipitation that includes information about past atmospheric circulation and mass imbalance in the polar regions. We present a novel adjoint method to reconstruct a climatic record by both optimally dating an ice-core and deriving from it a detailed accumulation history. The motivation of our work is the recent application of phase sensitive radar which measures the vertical velocity of an ice column. The velocity is dependent on the history of subsequent snow accumulation, compaction and compression; and in our inverse formulation of this problem, measured vertical velocity profiles can be utilized directly thereby reducing the uncertainty introduced by ice flow modelling. We first apply our method to synthetic data in order to study its capability and the effect of noise and gaps in the data on retrieved accumulation history. The method is then applied to the ice core retrieved from James Ross Island, Antarctica. We show that the method is robust and that the results depend on quality of the age-depth observations and the derived flow regime around the core site. The method facilitates the incorporation of increasing detail provided by ice-core analysis together with observed full-depth velocity in order to construct a complete climatic record of the polar regions.

Cenozoic accumulation history of a Pacific ferromanganese crust

1994 ◽  
Vol 125 (1-4) ◽  
pp. 105-118 ◽  
Author(s):  
G.M. McMurtry ◽  
D.L. VonderHaar ◽  
A. Eisenhauer ◽  
J.J. Mahoney ◽  
H.-W. Yeh
Keyword(s):  
Ferromanganese Crust ◽  
History Of ◽  
Accumulation History

On the Accuracy of Uranium-Series Dating: a Comparison with a Known Matrix Diffusion Case

1996 ◽  
Vol 465 ◽  
Author(s):  
K. Rasilainen ◽  
J. Suksi
Keyword(s):  
Mass Flow ◽  
Open System ◽  
Decay Chain ◽  
Matrix Diffusion ◽  
Uranium Series ◽  
Uranium Series Dating ◽  
Flow Information ◽  
History Of ◽  
Improved Accuracy ◽  
Accumulation History

ABSTRACTThe accuracy of uranium-series dating was studied quantitatively using the natural long-lived decay chains 4n+2 and 4n+3. An unusually well-bounded matrix diffusion case was used as the reference for USD simulations. The simulations applied the traditional closed and open system models, as well as detailed multistage models that incorporated the known accumulation history of the decay chain members. The results show clearly the improved accuracy and consistency in dating with detailed mass flow information.

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