Umber as a lithified REY-rich mud in Japanese accretionary complexes and its implications for the osmium isotopic composition of Middle Cretaceous seawater

Fujinaga, Koichiro; Nakamura, Kentaro; Ohta, Junichiro; Yano, Moei; Kuwahara, Yusuke; Yasukawa, Kazutaka; Takaya, Yutaro; Nakayama, Ken; Nozaki, Tatsuo; Kato, Yasuhiro

doi:10.1016/j.oregeorev.2021.104683

Cited by 5 publications

(1 citation statement)

References 104 publications

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“…[13][14][15] Lithied, siliceous deep-sea sediment (chert) and metalliferous sediment (umber) in accretionary complexes have been used to obtain the marine 187 Os/ 188 Os record before the Cenozoic. [16][17][18][19][20] The long-term uctuations of the marine 187 Os/ 188 Os record may also be used to date deep-sea deposits that lack age-diagnostic proxies by tting measured isotope ratios with a reconstructed marine secular 187 Os/ 188 Os curve. [21][22][23][24][25] Moreover, stable 187 Os/ 188 Os ratios in extraterrestrial materials oen mark apparent negative excursions of the 187 Os/ 188 Os record that allow detection of past meteorite impact events.…”

Section: Introductionmentioning

confidence: 99%

A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

Ohta

Nozaki

Sato

et al. 2022

J. Anal. At. Spectrom.

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Section: Introductionmentioning

confidence: 99%

A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

Ohta

Nozaki

Sato

et al. 2022

J. Anal. At. Spectrom.

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Discriminating chert origins using machine‐learning approaches

Wei

Sun

et al. 2023

Geological Journal

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Automatic techniques have not been applied in the geochemical discrimination of marine, terrestrial and hydrothermal cherts, which is critical to retrieving the paleoenvironmental information of ancient sedimentary basins. Here, we applied three supervised machine‐learning methods to analyse the labelled geochemical compositional data (32 major and trace elements) of cherts, including the support vector machine (SVM), sparse multinomial regression and linear discrimination analysis. Our results show that these machine‐learning methods can successfully discriminate different chert types, as the lowest classification score is 79%. Among the methods, the SVM is the most powerful approach (classification score 88%, on average), even though it is hard to be geochemically interpreted. Sparse multinomial regression and linear discrimination analysis are also efficient approaches (mean classification score 84%), which can be used to extract the important elements and the most representative sample for each chert type. Especially, the linear discrimination analysis can construct binary discrimination diagram superposed with biplot rays and posterior probability‐based decision boundaries, which could be quickly applied and explained by other researchers. Furthermore, the successful discrimination of different chert types indicates that cherts derived from different silica sources have different geochemical signatures, albeit mixing between different sources of silica during chert formation is common. Last, the general geochemical features of each chert type were summarised based on geochemical information extracted by machine‐learning methods and previous geochemical studies.

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Iron deposition during recovery from Late Devonian oceanic anoxia: Implications of the geochemistry of the Kawame ferromanganese deposit, Nedamo Belt, Northeast Japan

Kuwahara

Fujinaga

Nozaki

et al. 2022

Global and Planetary Change

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Umber as a lithified REY-rich mud in Japanese accretionary complexes and its implications for the osmium isotopic composition of Middle Cretaceous seawater

Cited by 5 publications

References 104 publications

A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

Discriminating chert origins using machine‐learning approaches

Iron deposition during recovery from Late Devonian oceanic anoxia: Implications of the geochemistry of the Kawame ferromanganese deposit, Nedamo Belt, Northeast Japan

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