Taenidium barretti ichnofabric and rainfall seasonality: Insights into dryland suites of Scoyenia ichnofacies

Author(s)

Nascimento, Diego Luciano ; Netto, Renata Guimaraes ; Batezelli, Alessandro ; Ladeira, Francisco Sergio Bernardes ; Sedorko, Daniel

• Document type: Journal article
• Source: JOURNAL OF PALAEOGEOGRAPHY-ENGLISH; v. 12, n. 1, p. 22-pg., 2023-03-02.

Abstract

The present work analyzes the monotypic Taenidium barretti ichnofabric developed in aban-doned channels and floodplains to understand its paleoecological significance in highly seasonal fluvial sys-tems. The data come from the Cretaceous paleosols of the Manlia Formation (Bauru Basin, SE Brazil), in which the T. barretti ichnofabric and rhizoliths represent the biotic record. Beetle larvae are considered to be the most likely T. barretti tracemakers in these paleosols. The intensity and recurrence of bioturbation suggest that the windows of opportunity for beetle population growth were very short and controlled by the pro-gressive substrate desiccation after flood cessation. The characteristics of the trace fossil assemblage suggest soil colonization by r-strategic organisms triggered by flooding events that provided the resource inputs necessary for their living during rainy seasons. The results also show that in fluvial systems with high discharge variations, the boundaries between a "pre-desiccation suite" and a "desiccation suite" in the Scoyenia ich-nofacies can be diffuse due to the short duration of colonization windows and progressive terrestrialization of floodplains and channels. Therefore, the frequency of flooding events, the lowered water table, and the rapidity of substrate desiccation constrained colonization by other burrowers and may be considered as first -order factors controlling the generation of a monotypic T. barretti ichnofabric. Thus, the monotypic Taenidium ichnofabric in the Scoyenia ichnofacies context is an ichnomarker of brief windows for colonization in highly seasonal environments. (AU)

• FAPESP's process: 15/17632-5 - Sedimentation and pedogenesis in Cretaceous continental sequences of the Bauru, Sanfranciscana, Parecis and Neuquén basins.
• Grantee: Alessandro Batezelli
• Support Opportunities: Regular Research Grants