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Titel |
Cosmogenic Nuclides 10Be–21Ne Burial Dating of Middle Miocene Sedimentary Formation of the Hongliu Valley in Southern Ningxia Basin: A Case of Isotopic Geochronology Study for the Cenozoic Sedimentary Strata |
VerfasserIn |
Yan Ma, Huiping Zhang, Weitao Wang, Jianzhang Pang, Dewen Zheng |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250129234
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Publikation (Nr.) |
EGU/EGU2016-9314.pdf |
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Zusammenfassung |
Chronology studies for the Cenozoic sedimentary strata based on the magnetostratigraphy
cannot afford the unique chronological sequences in the absence of absolute ages from
biostratigraphy or volcanic ash chronology. In situ-produced cosmogenic nuclides provide a
powerful tool for the sediment dating based on the time-dependent concentration ratio of two
nuclides, which are produced in the same mineral but with different half-lives.
Thereinto,10Be–26Al is the most widely used nuclide pairs, of which the available dating
range spans the Plio-Pleistocene. But the coupling of 10Be with the stable nuclide 21Ne
would significantly improve the burial dating range up to the middle Miocene, which is
promising in revolutionizing the chronology study for the Late Cenozoic terrestrial
sedimentary sequences. We have applied 10Be–21Ne pair for dating the middle
Miocene sediments of the Hongliu Valley in southern Ningxia basin. Two major
features of the sediments are involved in our study: (1) sediments originated from
the steady erosion of the source area, and (2) the burial depth of our sample after
deposition is time dependent due to the gradual accumulation of sediments into basin.
The post-burial nuclide production is estimated to be less than 3%, including the
contribution by muon interactions, of the total nuclide concentrations measured in
our sample. Our 10Be–21Ne analysis demonstrates the age of the burial sample is
12.4(+0.6/-0.4) Ma, and the erosion rate at the source area is 0.26±0.01 cm ka−1. The
sample’s burial age is consistent with the age constraint set by the Hongliugou
Formation (16.7–5.4 Ma) which we collected the sample in. Vertebrate fossils of
Platybelodon tongxinensis with an age between 12 and 15 Ma exhumated along with our
sample further verifies the reliability of our dating results for the middle Miocene
sediments.This study has shown the improved age range of cosmogenic-nuclide burial
dating method by incorporating the stable nuclide 21Ne, and has established the
feasibility of 10Be–21Ne pair in chronology studies for the Cenozoic sedimentary strata. |
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