Did mangrove communities exist in the Late Cretaceous of the Kristianstad Basin, Sweden?

Abstract

Previous inferences of oyster-dominated communities occupying mangrove-like depositional settings in the Kristianstad Basin, Sweden, during the late early Campanian are reassessed. A significant percentage of oysters (Acutostrea incurva) from the Belemnellocamax mammillatus zone in Bed 3 at Åsen bear indentations on their left valves indicating attachment to plant axes. Many of these axes bear morphological features characteristic of the distal subaerial portions of woody plant branches and appear to have been rafted into the marine environment rather than representing in situ mangrove stems and roots. Foraminiferal assemblages recovered from sediment within the oyster body cavities differ from modern mangrove-community associations by the absence of siliceous agglutinated Foraminifera, the presence of diverse and relatively abundant Lagenida, relatively common triserial Buliminida, and a notable percentage of planktonic taxa. Chondrichthyan teeth assemblages from the same beds are similarly incompatible with the interpretation of a mangrove depositional environment based on comparisons with the distribution of related extant taxa. Apart from oyster shells and belemnite rostra, these beds are notably depauperate in diversity and abundance of macroinvertebrate remains compared with coeval carbonate shoal and rocky shoreline assemblages from the same basin. The collective palaeontological and sedimentological evidence favours an inner neritic sandy-substrate setting, but not nearshore or mangrove-like depositional environment for the oyster-rich Bed 3 at Åsen. The absence of mangrove-like assemblages at Åsen is consistent with the development of modern mangrove ecosystems much later (during the Maastrichtian and Cenozoic) based on the global palynological record.

Neutron tomography, fluorescence and transmitted light microscopy reveal new insect damage, fungi and plant organ associations in the Late Cretaceous floras of Sweden

“…Various leafless axis impressions and compressions have been reported from the Ryedal Sandstone (Conwentz 1892), the basal carbonaceous succession at Åsen, lignites at nearby Axeltorp (Nykvist 1957), and as impressions on encrusting oysters from the overlying carbonate succession at Åsen (McLoughlin et al 2018). Some examples bearing dense, helically arranged, leaf scars (Fig.…”

“…The oldest Cretaceous plant fossils are palynological assemblages from subsurface Albian strata recovered from a borehole near Österslöv, northern Skåne (Guy-Ohlson 1984; Table S1). A formal lithostratigraphic scheme for the basin has never been established and, traditionally, local geological correlations have employed biostratigraphic subdivisions of the strata (summarized by Einarsson 2018). Accessible strata range from lower or lower middle Santonian (Gonioteuthis westfalica westfalica Zone, sensu Christensen 1997) to uppermost Campanian (Belemnella lanceolata Zone; Thibault et al 2012;Voigt et al 2012) and were deposited at palaeolatitudes of 47-49°N (Kent & Irving 2010;Van Hinsbergen et al 2015).…”

“…Palaeoshorelines of the northeastern coast of the basin are recorded from the famous locality of Ivö Klack, where basement rocks are encrusted by Cretaceous (Campanian) epizoan brachiopods, mollusks, corals and other invertebrates (c. 200 shell-bearing invertebrate species in total; Surlyk & Christensen 1974;Surlyk & Sørensen 2010;Sørensen et al 2012). Shoreline and shallow embayment deposits also occur at Åsen, where Campanian oysters are interpreted to have attached to transported woody debris from terrestrial arborescent plants (McLoughlin et al 2018). The deposits at Ryedal and Åsen yielding plant fossils for this study (Fig.…”

“…Besides plant microspores, pollen and angiosperm mesofossils, quarries at Åsen and nearby Axeltorp yielded conifer (Nykvist 1957) and angiosperm woods (Herendeen 1991), conifer leaves and cones (Srinivasan & Friis 1989), seeds (Kunzmann & Friis 1999), and lycopsid megaspores (Koppelhus & Batten 1989). Overlying the continental deposits at Åsen are marine marls and carbonates of latest early to earliest late Campanian age (Iqbal 2013;Einarsson et al 2016;Siversson et al 2016) that have yielded a rich invertebrate and vertebrate fauna (Sørensen et al 2013;Einarsson 2018;McLoughlin et al 2018, and references therein).…”

“…However, as part of a campaign to document Late Cretaceous adpression floras through central and northern Europe, the Campanian mega-and palynoflora of the Vomb Trough was described recently by . Fossil plant axes were also documented by McLoughlin et al (2018) from associated marine deposits where they acted as substrates for Late Cretaceous sessile marine invertebrates. Relatively few other records of Cretaceous terrestrial fossils from the Kristianstad Basin have been published over the past 200 years (Table S1), and these are not investigated further in this study.…”