Impacts of natural irradiation on sedimentary organic matter–A review

Yin, Mingming; Snowdon, Lloyd R.; Silva, Renzo C.; Huang, Haiping; Larter, Steve

doi:10.1016/j.orggeochem.2023.104602

Cited by 2 publications

(1 citation statement)

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“…The loss of CL emission in samples which still exhibit strong organic fluorescence is here speculatively attributed to radiolytic alteration. Radiolytic alteration of sedimentary organic matter is a function of radiation intensity, duration, degree of dissemination of radioactive sources, organic matter density, and the abundance of water 35 , 36 . While there is no clear relationship between radiation dose (α-particle fluence calculated from bulk rock U and Th content, Table 1 ) and CL emission loss in our samples, we suggest that incorporation of U into the sedimentary organic matter of certain samples may have caused increased polymerization and therefore decreased CL emission from quenching effects.…”

Section: Discussionmentioning

confidence: 99%

Cathodoluminescence differentiates sedimentary organic matter types

Hackley,

McAleer,

Jubb

et al. 2024

Sci Rep

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High-resolution scanning electron microscopy (SEM) visualization of sedimentary organic matter is widely utilized in the geosciences for evaluating microscale rock properties relevant to depositional environment, diagenesis, and the processes of fluid generation, transport, and storage. However, despite thousands of studies which have incorporated SEM methods, the inability of SEM to differentiate sedimentary organic matter types has hampered the pace of scientific advancement. In this study, we show that SEM-cathodoluminescence (CL) properties can be used to identify and characterize sedimentary organic matter at low thermal maturity conditions. Eleven varied mudstone samples with a broad array of sedimentary organic matter types, ranging from the Paleoproterozoic to Eocene in age, were investigated. Sedimentary organic matter fluorescence intensity and CL intensity showed an almost one-to-one correspondence, with certain exceptions in three samples potentially related to radiolytic alteration. Therefore, because CL emission can be used as a proxy for fluorescence emission from sedimentary organic matter, CL emission during SEM visualization can be used to differentiate fluorescent from non-fluorescent sedimentary organic matter. This result will allow CL to be used as a visual means to quickly differentiate sedimentary organic matter types without employing correlative optical microscopy and could be widely and rapidly adapted for SEM-based studies in the geosciences.

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Section: Discussionmentioning

confidence: 99%