Bioerosion in shell beds from the Pliocene Roussillon Basin, France: Implications for the (macro)bioerosion ichnofacies model
Bioerosion in shell beds from the Pliocene Roussillon Basin, France: Implications for the (macro)bioerosion ichnofacies model
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法国上新世鲁西永盆地贝壳层中的生物侵蚀：对（宏观）生物侵蚀地貌模型的影响
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
J. Martinell
中科院分区：
文献类型：
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作者：
J. Gibert;R. Domènech;J. Martinell
Nefiach （Roussillon盆地，法国东南部）海相上新世包括几个由牡蛎和扇贝组成的壳层，这些壳层具有丰富多样的生物侵蚀痕迹化石组合。最丰富的痕迹化石是棘足类和多placophorans对覆盖在贝壳表面的藻类和其他微生物的啃食活动产生的Gnathichnus pentax和Radulichnus inopinatus。其他生物侵蚀痕迹包括多毛动物住所（Caulostrepsis taeniola和Maeandropolydora sulcans），海绵钻孔系统（Entobia isp.）和罕见的苔藓虫产卵（Pinaceocladichnus isp.），捕食结构（Oichnus simplex和修复的硬噬疤痕）和有孔虫固定坑（Centrichnus cf.eccentricus）。微量化石组合记录了壳层在中等能量环境下的短期生物侵蚀，这证明了在大多数情况下由“瞬时”行为产生的表生或浅层内生结构的优势。该组合可归属于Gnathichnus鱼相，并与同一地理区域的上新世岩岸（即Entobia鱼相）形成对比。证实了Gnathichnus鱼相是一种典型的鱼相，并证明了其自侏罗纪以来的周期性。在中生代和新生代，可以用Entobia和Gnathichnus两种岩相代替已有的锥虫岩相，而锥虫岩相在古生代仍然有效。
The marine Pliocene at the locality of Nefiach (Roussillon Basin, SE France) includes several shell beds constituted by oysters and scallops that bear a diverse and abundant bioerosion trace fossil assemblage. The most abundant trace fossils are Gnathichnus pentax and Radulichnus inopinatus, produced by the grazing activity of echinoids and polyplacophorans upon algae and other microorganisms coating shell surfaces. Other bioerosion traces include polychaete dwellings (Caulostrepsis taeniola and Maeandropolydora sulcans), sponge boring systems (Entobia isp.), and rare bryozoan bor− ings (Pinaceocladichnus isp.), predation structures (Oichnus simplex and repaired durophagous scars), and foraminiferal fixation pits (Centrichnus cf. eccentricus). The trace fossil assemblage records short−term bioerosion in shellgrounds in a moderate energy setting as evinced by the dominance of epigenic or shallow endogenic structures produced in most cases by “instantaneous” behaviors. The assemblage can be assigned to the Gnathichnus ichnofacies, and it contrasts with that found in Pliocene rocky shores in the same geographic area, which are examples of the Entobia ichnofacies. The Gnathichnus ichnofacies is validated as an archetypal one and its recurrency demonstrated since the Jurassic. Entobia and Gnathichnus ichnofacies have to be used in the Mesozoic and Cenozoic as substitutes of the previously existing Trypanites ichnofacies, which is still valid in the Palaeozoic.