Kerogen morphology and geochemistry at the Permian–Triassic transition in the Meishan section, South China: Implication for paleoenvironmental variation

Abstract

Abstract:Detailed fluorescent microscopic observations and organic geochemical analyses for insoluble sedimentary organic matter (kerogens) are conducted on the end-Permian to earliest Triassic sediments in the Meishan section A of South China. The main objectives of the present study are to reconstruct variations of marine and terrestrial environments, and to evaluate bulk characteristics of terrestrial input in the palaeo-Tethys ocean for the Permian -Triassic boundary (PTB). Most of kerogens in the Meishan section are mainly composed of marine algae-derived amorphous organic matter, while terrestrial plant-derived amorphous organic matter is remarkably dominant in the mass extinction horizon reported previously. The relative abundances of marine organic matter may vary depending on marine production rather than terrestrial input in the palaeo-Tethys associated with changing terrestrial vegetation. We also identified aromatic furans as major compounds in kerogen pyrolysate of all layers. It is possible that sources of aromatic furans with alkyl group, fungi and lichen, proliferated as disaster biota in terrestrial ecosystem through the PTB. Higher abundances of herbaceous organic matter are observed in the layers above the mass extinction horizon. However, the conifer biomarker retene can be identified in kerogen pyrolysates of all layers. These results imply that the productions of herbaceous plants increased as dominant pioneer biota in early stage of recovery for terrestrial ecosystem after its collapse, but also that woody plant potentially continued to be produced in land area throughout the end-Permian and earliest-Triassic.

Optical and geochemical characterization of Upper Sinemurian (Lower Jurassic) fossil wood from the Lusitanian Basin (Portugal)

“…In a few samples, palynomorphs or the AOM of marine origin are observed (e.g., Figs. 3(a), (b), (c) and (g)) (see, for example, Tyson, 1995;Mendonça Filho et al, 2011;Sawada et al, 2012 for a detailed description). It is possible to observe that the wood particles present both fluorescent and nonfluorescent particles in all the samples (e.g., Fig.…”

Kerogen characterisation and petroleum potential of the Late Cretaceous sediments, Chad (Bornu) Basin, northeastern Nigeria

“…Both the morphology of the AOM under transmitted light microscope and the incident blue light fluorescence were used to identify the types of amorphous particles in the samples (Tyson, 1995;Tribovillard et al, 2001;Ercegovac & Kostic, 2006). This is because the method of using only fluorescence light microscopic observation to differentiate between AOM may show some discrepancies, because overmature AOM may not fluoresce (Durand, 1980;Sawada et al, 2012).…”

“…Description of insoluble organic matter (kerogen) identified in the studied samples under transmitted and fluorescent microscope. Classification is based onTyson (1995),Ercegovac & Kostic (2006),Sawada (2006),Sawada et al (2012).…”