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Néraudeau, Didier, Philippe, Marc, Albani, Abderrazak El, Moreau, Jean-David, Polette, France, Martin, Jean-Paul Saint (2022): Taphonomie et minéralisation de bois carbonatisés du Purbeckien de l'Usine, à Cherves-Richemont (Charente). Geodiversitas 44 (24): 665-682, DOI: 10.5252/geodiversitas2022v44a24

A palynological analysis of 45 samples from six mid-Cretaceous amber-bearing outcrops from Charentes has been carried out. A total of 227 taxa have been recorded in the studied palynofloras. Palynological data support earlier evidence and indicate an early Cenomanian age for the assemblages. The heterogeneous compositions of the palynofloral assemblages indicate the existence of different coastal depositional settings with a variable but usually weak marine influence. The local vegetation was subdivided in various types including herbaceous formations integrating ferns and eudicots which may have colonised frequently-disturbed, fluvial, open environments and xeric arboreal communities dominated by Cheirolepidiaceae and probably integrating drought- and/or salt-tolerant angiosperms and ferns (Anemiaceae and Gleicheniaceae) and other gymnosperms (Araucariaceae, Ginkgoales and scarce Cycadales and Gnetales). The existence of riparian and freshwater wetland communities integrating taxodioids, aquatic and/or hygrophilous angiosperms, ferns, lycopods, mosses and clubmosses is proposed. Coastal/?lagoonal counterparts including plants tolerant to periodical floods by saline or brackish waters is suggested by palynological evidence. Conifer forests mainly integrating Pinaceae and Podocarpaceae in raised hinterlands may also be interpreted on the basis of taphonomical considerations. The wide variety of depositional settings inferred by the palynological data support enhanced transport capabilities for amber and/or a widespread occurrence of producers in local vegetation during the early Cenomanian.

International audience; A new Cenomanian amber- and plant-bearing deposit has been discovered at Neau, in the Mayenne department (France). The Cenomanian fossiliferous lignites are located in karst filling in a substratum of Cambrian limestones. The amber corresponds mainly to tiny millimetric grains, devoid of arthropod inclusions, but rich in microorganisms, especially the sheated bacteria Leptotrichites resinatus , and containing pollen grains ( Classopollis ) and wood fibers (Araucariacae or Cheirolepidiaceae). The lignites provide abundant conifer and ginkgoale cuticle fragments ( Frenelopsis , Eretmophyllum ) and a lot of palynomorphs ( e.g. Gleicheniidites senonicu s, Cyathidites , Deltoidospora , Appendicisporites and Cicatricosisporites ). The chemical signature of the amber suggests it was produced by conifers of the extinct family Cheirolepidiaceae. According to the palynological assemblage, the age of the lignites is upper lower Cenomanian or lower mid Cenomanian. The deposit environment corresponded to the upstream portion of a mangrove or the most inner part of a lagoon.; Un nouveau site à ambre et plantes du Cénomanien a été découvert à Neau, en Mayenne (France). Les lignites fossilifères cénomaniens sont localisés dans des remplissages de karsts développés dans des calcaires du Cambrien. L’ambre se présente essentiellement sous forme de grains millimétriques, dépouvus d’inclusions d’arthropode, mais riches en microorganismes, notamment en bactéries gainées de type Leptotrichites resinatus , et contenant des grains de pollen ( Classopollis ) et des fibres de bois (Araucariacae ou Cheirolepidiaceae). Les lignites fournissent d’abondants fragments de cuticules de conifères et de ginkgoales ( Frenelopsis , Eretmophyllum ) et une grande quantité de palynomorphes ( e.g. Gleicheniidites senonicu s, Cyathidites , Deltoidospora , Appendicisporites et Cicatricosisporites ). La signature chimique de l’ambre suggère qu’il a été produit par des conifères de la famille éteinte des Cheirolépidiacées. D’après l’assemblage palynologique, l’âge des lignites est Cénomanien inférieur tardif ou Cénomanien moyen basal. L’environnement de dépôt correspondait à la partie amont d’une mangrove ou la partie la plus interne d’un lagon.

International audience; The Upper Cretaceous lignite deposits of La Garnache, Vendée (western France), consist of two lignitic clay series, Garnache 1 and Garnache 2, separated by a fault. The first series cropped out to the south of the fault during road works until 2002 but is now covered by an embankment. It has provided numerous pieces of amber containing arthropod and microorganism inclusions. The second lignitic series, exposed to the north of the fault, is rich in fossil wood but devoid of amber. Palynological analysis of Garnache 1 revealed several Normapolles species belonging to the genera Atlantopollis, Complexiopollis, Osculapollis, Plicapollis and Trudopollis, but larger forms typical of Senonian deposits are absent. By contrast, Garnache 2 proved to be dominated taxonomically and numerically by spores (Appendicisporites, Camarozonosporites, Gleicheniidites, Patellasporites, Stereisporites), associated with a few gymnosperm (Cerebropollenites, Phyllocladidites, Classopollis) and angiosperm (Liliacidites, Retitricolpites and a single specimen of the Normapolles Complexiopollis) taxa. Garnache 1 is, therefore, younger than Garnache 2, the latter being clearly Cenomanian in age whereas Garnache 1 is more likely to be Turonian. Lignitic clay of Garnache 1 contains numerous translucent, orange to red, pieces of amber. Vendean amber is rich in aquatic arthropods, such as tanaids and epicarideans (Crustacea), as well as marine or brackish siliceous microorganisms such as diatoms and sponge spicules. These aquatic inclusions indicate that resin-producing trees grew along and close to the seashore. The amber-bearing clay was deposited in a calm, estuarine or lagoonal, muddy environment.

International audience; Diagnoses of the Normapolles pollen genera Hungaropollis, Krutzschipollis, Longanulipollis, Oculopollis and Trudopollis and 55 of their species are emended and many specimens illustrated in order to provide a basis for more successful and consistent identification than has been possible hitherto. These taxa were recovered from palynological preparations of selected samples from Upper Cretaceous deposits in Europe and the eastern USA. As indicated on an accompanying range chart the majority are encountered in Santonian and/or Campanian deposits. Eleven of the species described have been transferred from other genera and are therefore in new combinations, namely: Hungaropollis granulatus (Kedves et Herngreen), Longanulipollis coronatiformis (Góczán et Siegl-Farkas), L. orbicularis (Góczán), L. ornatus (Kedves et Diniz), L. parvoculus (Góczán), L. skarbyae (Kedves et Diniz), Oculopollis artifex (Weyland et Krieger), O. rector (Pflug), O. triceps (Skarby), Trudopollis cuneolis (Góczán et Siegl-Farkas), and T. spinulosus (Skarby). Six are new: Hungaropollis pinguis, Krutzschipollis cucullus, K. immanis, Longanulipollis amabilis, L. lobus and Oculopollis viriosus. Thirteen genera are regarded as synonyms of Hungaropollis (Aveiropollenites and Romeinipollenites), Longanulipollis (Coronatipollis, Intercalaripollis, Portaepollenites and Verruoculopollis), Oculopollis (Druggipollenites, Pseudoculopollis and Semioculopollis) and Trudopollis (Cuneipollis, Felderipollenites, Hofkeripollenites and Kriegeripollenites) respectively. As a result of some of these nomenclatural changes 14 other species are in new generic combinations but are not otherwise considered. Seven morphotypes are identified in open nomenclature and two placed in comparison. This taxonomic synthesis, which updates work published since the 1950s, is aimed primarily at rendering biostratigraphic analyses easier, but it is also a necessary first step towards the resolution of Normapolles taxonomy and the relationships between these pollen grains and biological species.