Early Jurassic microbial mats—A potential response to reduced biotic activity in the aftermath of the end-Triassic mass extinction event

Summary, in English

Wrinkle structures are microbially induced sedimentary structures (MISS) formed by cyanobacteria and are common in pre-Cambrian and Cambrian siltstones and sandstones but are otherwise rare in the Phanerozoic geological record. This paper reports the first discovery of Mesozoic wrinkle structures from Sweden. These are preserved in fine-grained and organic-rich heterolithic strata of the Lower Jurassic (Hettangian) Höganäs Formation in Skåne, southern Sweden. The strata formed in a low-energy, shallow subtidal setting in the marginal parts of the Danish rift-basin. Palynological analyses of fine-grained sandstones hosting the wrinkle structures show that the local terrestrial environment probably consisted of a wetland hosting ferns, cypress and the extinct conifer family Cheirolepidaceae. Palynostratigraphy indicates a Hettangian age, still within the floral recovery phase following the end-Triassic mass extinction event. The finding of wrinkle structures is significant as the presence of microbial mats in the shallow subtidal zone, (in a deeper setting compared to where modern epibenthic microbial mats grow) suggests decreased benthic biodiversity and suppressed grazing in shallow marine environments in the early aftermath of the end-Triassic mass extinction event.

• Author: Olof Peterffy; Mikael Calner; Vivi Vajda
• Department/s: Lithosphere and Biosphere Science
• Publishing year: 2016-12-15
• Language: English
• Pages: 76-85
• Publication/Series: Palaeogeography, Palaeoclimatology, Palaeoecology
• Volume: 464
• Links: http://dx.doi.org/10.1016/j.palaeo.2015.12.024
• Document type: Journal article
• Publisher: Elsevier
• Topic: Geology
• Keywords: Cyanobacteria; Hettangian; Mass extinction; Microbial mat; Sweden; Wrinkle structures
• Status: Published
• ISBN/ISSN/Other: ISSN: 0031-0182