T217 From Coastal Lowlands to Shallow Shelf: Environmental Processes of the Coastal Critical Zone through Time and Space

Wednesday, 18 October 2023
8:00 AM - 12:00 PM
303

PEAT TAPHONOMY AND FUNGAL DISTRIBUTIONS PRESERVED IN A COASTAL LIGNITE FROM THE MIOCENE OF NORTHWESTERN PERU

Paper number: T217-3
Program: Technical Sessions
Time: 8:30 AM – 8:45 AM

Authors

Abstract

Fungi provide key ecosystem services in coastal peatlands, both from the perspective of nutrient flow supporting food webs and from the perspective of peat taphonomy. Relatively little is known about fungal communities associated with modern Rhizophora-dominated mangrove peats in South America, much less about fungal communities associated with and impacting peat taphonomy and preservation during the Miocene Climate Optimum. Miocene site P6 from the Fungi in a Warmer World sampling campaign in northwestern Peru is a succession of mollusk and gastropod-rich laminated silty shale that encases lignite beds. The succession is capped by coarser sediments that range from siltstone to sandstone. Most sediments in the succession contain abundant micro foraminifera, in addition to palynomorphs. The lignite is known to be low rank, with huminite reflectance below 0.3% Rr. The maceral assemblage contains textinite and other huminite macerals, as well as funginite and various liptinites, including cutinite and resinite. Previous work has indicated that the dominant plant palynomorphs preserved are Rhizophora, Arecaceae, Ficus, and ferns. Fungal palynomorphs are especially diverse throughout the section. They are primarily representative of plant saprotrophs, especially helicosporous and other conidia that are associated with decomposition in waterlogged environments, although dung fungi, such as Delitschia sp., also occur. This study examines coastal peat preservation and taphonomic history from the lens of coupled organic petrography and fungal palynology, and provides a first record of fungal community succession in a Rhizophora-dominated Miocene peat.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-395145

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