Kellwasser horizons, sea-level changes and brachiopod–coral crises during the late Frasnian in the Namur–Dinant Basin (southern Belgium): a synopsis

Abstract

In Belgium, the Lower Kellwasser Event (LKW) corresponds to the relative sea-level maximum of the first ('Aisemont sequence' (AS)) of the two late Frasnian third-order sequences that are recognized here, but the Upper Kellwasser Event (UKW) may have been triggered by a series of tsunamites. The end of the middle Frasnian carbonate platform and reefs is caused by the sea-level drop and emersion of the last middle Frasnian third-order sequence ('Lion sequence') in the Lower rhenana Zone. The end of the 'Petit-Mont' mudmound growth during the transgressive (TST) and highstand (HST) systems tracts of the AS was caused by sea-level fall and emersion at the top of this sequence. The coral and brachiopod extinction in the Upper rhenana Zone, during the second late Frasnian third-order sequence ('Lambermont sequence' (LS)), is progressive and due to the widespread development of the dysoxic and anoxic facies, before the UKW. Only the LS TST has been identified. No sea-level fall has been recognized in relation to the UKW or near the Frasnian-Famennian boundary. The late Frasnian extinctions are more likely to be related to the decrease in the atmospheric oxygen rate and its impact on marine environments and, to complete, the UKW.

New insights on Tournaisian–Visean (Carboniferous, Mississippian) athyridide, orthotetide, rhynchonellide, and strophomenide brachiopods from southern Belgium

“…Elsewhere in the world, several authors reported their occurrence in Frasnian and Famennian deposits (e.g., Karapetov, 1971;Xu (in Xu and Yao, 1988), Mergl and Massa, 1992;Brice in Brice et al, 2005;Alekseeva, 2011;Popov in Ghobadi Pour et al, 2013;Baranov et al, 2016;Zong et al, 2016). The absence of Leptaeninae from the Givetian-Famennian interval in southern Belgium is quite strange as, during the same time, the long-ranging orthide genus Schizophoria, which was already associated to the last Eifelian Leptaeninae, did not temporarily disappear and is even one of the first to recover after the FrasnianFamennian Crisis in Belgium (Mottequin, 2008b;Mottequin and Poty, 2016), and persisted after the Hangenberg Crisis. They flourished again during the Tournaisian-Visean, notably in Europe (e.g., Demanet, 1934;Pocock, 1968;Żakowa, 1989).…”

Devonian climate, sea level and evolutionary events: an introduction

“…Mottequin & Poty (2015) summarize the brachiopod and coral evidence of the Ardennes, which in the middle and upper Frasnian can be assigned to a succession of clearly defined third-order sequences. The end of regionally famous reef episodes (mostly mudmounds) was linked with regressions and sequence boundaries, whilst the Lower and Upper Kellwasser levels represent maximum transgressions.…”

“…Some contributions of this volume were first presented at the 2013 meeting or subsequently, for example at the IGCP 596-SDS Symposium in Brussels in September 2015 (Mottequin et al 2015).…”

Upper and uppermost Famennian (Devonian) brachiopods from north-western France (Avesnois) and southern Belgium

“…Copper, 2002), and was followed by a relatively rapid postextinction recovery at the base of the Famennian among the athyridides, spiriferides and rhynchonellides, which is well-documented in southern Belgium (e.g. Sartenaer, 1956Sartenaer, , 1968Sartenaer, , 1972Mottequin, 2008a, b, c;Mottequin & Poty, 2016). Brachiopods are particularly abundant in the argillaceous environments of the lower part of the lower Famennian; athyridides (Cleiothyridininae), spiriferides (Cyrtospiriferidae) and rhynchonellides (Leiorhynchidae, Pugnacidae, Trigonirhynchiidae) dominated the rest of the brachiopod faunas including orthides, orthotetides, and productides.…”