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2022 (vol. 22)

Calcareous nannofossils of the uppermost Bedoulian and lower Gargasian of La Tuilière - St-Saturnin-lès-Apt (area of the Aptian stratotype, Vaucluse, SE France)
Bernard C. LAMBERT

 | HTML  | PDF [3,071 KB]  | DOI: 10.2110/carnets.2022.2217

 Abstract:  An 148 m composite section located in the Gargas area stratotype in southeastern France has been studied for its calcareous nannofossil content. The four sections span the upper Bedoulian to lower Gargasian with the stadial boundary located within the basal section south of the village of Clavaillan. A total of 75 samples was processed to inventory taxonomy and stratigraphic distributions.
Eprolithus floralis is present at the base of the stratigraphic succession. The lowest occurrence of this species, which marks the base of Subzone NC7A, has been documented in the uppermost lower Aptian (Bedoulian) in other sections in southeastern France. The highest occurrence of the genus Micrantholithus has been utilized to delineate the base of Subzone NC7B. This subzonal boundary was placed at 48 m in the Les Gays I section (113.5 m in the composite) below the lowest occurrence of the foraminifer Globigerinelloides ferreolensis in the suprajacent sample (50 m). The lowest occurrence of Braarudosphaera africana is identified as a regional biohorizon in lower Subzone NC7A and a local proxy for the Bedoulian/Gargasian boundary. This event was placed at 15.5 m in the Clavaillan section at the base of the Dufrenoyia furcata Zone and within the "Niveau Blanc inférieur" marker bed (NB1).
The genus Nannoconus is abundant to very abundant in all samples examined. Taxonomic rigor has resulted in the recognition of five main morphologic groups (A-E), including all but one of the 15 species discriminated over this relatively short stratigraphic interval. Four main Nannoconus assemblage biozones - with one subdivision - have been distinguished through semi-quantitative analyses and organized relative to these taxonomic groupings. Assemblage Biozone B is restricted to the Bedoulian and has been correlated to the lower portion of Subzone NC7A (i.e., NC7A1). Assemblage biozones GI and GII (A-B) have been correlated to the upper portion of Subzone NC7A (i.e., NC7A2) and Biozone GIII to Subzone NC7B within the Gargasian.
Assipetra is another solution-resistant genus included in semi-quantitative analyses, where both its species were separated into small and large forms based on a size of 10 μm. The highest percentages of large morphotypes are within the Bedoulian in the lower 10.5 m of the Clavaillan section, roughly coeval to an acme of large Assipetra observed in the basal portion of the Serre Chaitieu section in the nearby Vocontian Basin.

Carnets Geol., vol. 22, no. 17, p. 745-793

Online since November 11, 2022


Palaeoentomological (fossil insects) outcrops in Lebanon
Sibelle MAKSOUD, Bruno R.C. GRANIER & Dany AZAR

 | HTML  | PDF [7,133 KB]  | DOI: 10.2110/carnets.2022.2216

 Abstract:  With 35 Cretaceous outcrops yielding fossil insects, either in amber or as rock (marls, limestones, cinerite, or dysodile) impressions-compressions (adpressions), Lebanon has continuously contributed significantly to the advance of palaeoentomology and to our understanding of entomological evolution and palaeobiodiversity. Compared to its small surface area, this country can be considered among the richest of fossil insect outcrops. This is due to its geological history and mainly to its forest, fluvial - lacustrine tropical and proximal marine subtropical palaeoenvironments plus Peritethys equatorial and subequatorial palaeogeography during the Lower and "Middle" Cretaceous. Herein, an exhaustive review of all outcrops with insects is given. A list of all fossil insects described from Lebanon is provided.

Carnets Geol., vol. 22, no. 16, p. 699-743

Online since September 14, 2022


A new discoid heliolitid (Proporidae) from the Upper Ordovician of the Baltic area: Morphology and modalities of increase
Yves PLUSQUELLEC, Jaap EYZENGA & Percy S.F. van KEULEN

 | HTML  | PDF [1,242 KB]  | DOI: 10.2110/carnets.2022.2215

 Abstract:   A species of Proporidae (Heliolitida) forming very small, discoid coralla, is fully described. It is mainly preserved in natural moulds in the Öjlemyr chert, an erratic silicified limestone found in Eridanos deposits surfacing in the west and north-east of the Dutch Overijssel-province and adjoining German area, generally accepted to be Uppermost Katian. The material is assigned to the rehabilitated Pinacopora Nicholson & Etheridge, 1878, a genus closely allied to Propora Milne-Edwards & Haime, 1849, and a new species, Pinacopora baltica is named. The main feature of this species, besides the characteristics of the genus and the biometric data, is the presence of wide, short, and convex septal ridges bearing scattered septal spines, alternating with narrow interseptal furrows. For the first time in heliolitids a pleurodictyoid pattern of growth is described. Only two species of Pinacopora are recorded: P. baltica n. sp. (Upper Ordovician) and P. grayi Nicholson & Etheridge, 1878 (Lower Silurian), respectively from Baltica and Laurentia.

Carnets Geol., vol. 22, no. 15, p. 685-698

Online since September 14, 2022


Nomenclatural Note, p. 684


Tethysian, Tethyan or ... Tethys Ocean and Tethys
Bruno GRANIER

 | HTML  | PDF [125 KB]  | DOI: 10.2110/carnets.2022.22EN1

 Abstract:  Tethys is a stand-alone modern noun, which does not require a qualifier in the English language. The use of the qualifiers Tethyan or Tethysian should be strongly discouraged. Taxa the names of which comprise the stem -tethy- are named after the Greek Goddess; those the names of which bear the stem -tethys- are named after the German (Suess, 1901), French (Suess, 1902) and English (Suess, 1908) Tethys Ocean. There was too much confusion on these two last points.

Thanks to our German-speaking readers (Olaf Elicki, Mike Reich, Torsten Scheyer, Ekbert Seibertz, ...) for having reported some grammatical errors: for instance, in the first table, one should read "(die) Tethys" instead of "(der) Tethys". [2022-08-12]

 
Carnets Geol., vol. 22, Editorial Note 1, p. 681-683

Online since August 10, 2022


The Lower Cretaceous Tuburan Limestone of Cebu Island, Philippines: Microfacies, micropalaeontology, biostratigraphy, and palaeogeographic perspectives
Jerali RODRIGO & Felix SCHLAGINTWEIT

 | HTML  | PDF [4,570 KB]  | DOI: 10.2110/carnets.2022.2214

 Abstract:  The occurrence of orbitolinid-bearing shallow water limestone blocks (Tuburan Limestone) incorporated into the volcanic series from Cebu Island, Central Philippines, has been known since the 1950's. Taxonomic studies including solid biostratigraphic data however are lacking or not substantiated. Herein we report the occurrence of Mesorbitolina texana (Roemer), transitional forms between M. texana and M. subconcava (Leymerie), Mesorbitolina birmanica (Sahni), Palaeodictyoconus actinostoma Arnaud-Vanneau & Schroeder, Neorbitolinopsis conica (Matsumaru), Paracoskinolina sp. and other benthic foraminifera (Akcaya, Praechrysalidina, Vercorsella) indicating a latest Aptian age. The previously accepted Late Albian age for the Tuburan Limestone based on Neorbitolinopsis conulus (Douvillé) is rejected herein and suggested as a misidentification with the recently revised Aptian - Lower Albian Neorbitolinopsis conica (Matsumaru). The general poverty of Lower Cretaceous dictyoconids in the Tuburan Limestone is interpreted as being caused by the lack of suitable extensive lagoonal facies that is generally typical for carbonate platforms of passive continental margins. The observed microfacies types instead refer to external platform margin settings with corals, stromatoporoids, sclerosponges (e.g., Acanthochaetetes), and planktic foraminifera. The recovered (micro) fauna from Cebu Island shows striking similarities to assemblages reported from Western and Mid-Pacific guyots but with indicated younger ages (up to the late Albian) based on data that - in our opinion - do not stand up to close scrutiny. Finally, a model is proposed interpreting the Tuburan Limestone from Cebu Island as remnants of a former carbonate cover of a guyot that originated as a volcanic island in the Western-Central Pacific, and later became incorporated into an accretionary wedge/mélange zone due to subduction-collisional processes.

Carnets Geol., vol. 22, no. 14, p. 631-679

Online since August 10, 2022


Tithonian-Hauterivian chronostratigraphy (latest Jurassic-Early Cretaceous), Mediterranean-Caucasian Subrealm and southern Andes: A stratigraphic experiment and Time Scale
Robert W. SCOTT

 | HTML  | PDF [1,106 KB]  | DOI: 10.2110/carnets.2022.2213

 Abstract:  New radioisotopic dates of Tithonian-Hauterivian strata in the Neuquén Basin significantly recalibrate Early Cretaceous numerical ages. In order to evaluate the implications of these revised ages, a graphic correlation experiment of twenty-three Andean Tithonian to Hauterivian sections integrated the ranges of 254 species, sequence boundaries, polarity chrons, and radioisotopic ages that compose the ANDESCS DB. This database accurately reproduces the order of Andean ammonite zones and places them in a relative metric scale of a composite reference section. The ranges in the ANDESCS DB were correlated with the LOK2016 DB that comprises Tithonian-Albian ammonites, calpionellids, nannofossils, and polarity chrons in Mediterranean-Caucasian Subrealm stage reference sections. In 2017 these ranges were calibrated to GTS2016 mega-annums (MA). Although most Andean ammonoids were endemic to the Indo-Pacific Subrealm, nannofossils, calpionellids and polarity chrons were present in both areas.
This stratigraphic experiment correlates base Berriasian as defined in France within the Substeueroceras koeneni Zone. In Andean sections this boundary is correlated with the Crassicolaria/Calpionella zone boundary dated at about 141 Ma. The base of the Valanginian defined by Calpionellites darderi correlates with the Neocomites wichmanni Zone of the Neuquén Basin (NB) recalibrated at 139.50 Ma, which is confirmed by multiple dates in Argentina, Mexico, Tibet, and elsewhere. The base Hauterivian correlates with base of Holcoptychites neuquensis Zone in the NB recalibrated at 131 Ma. Top of Hauterivian is in the Sabaudiella riverorum Zone in the NB and is dated at 127 Ma below an unconformity.
Previous cyclostratigraphic astrochronologic cycles are averaged and calibrate the duration of the Tithonian at 5.67 myr, the Berriasian at 5.27 myr, the Valanginian at 5.30 myr, and the Hauterivian at 5.60 myr. The age of each stage is recalibrated by adding revised durations to the most common age of base Valanginian of 139.5 Ma. These ages revise the Berriasian to Hauterivian stages time scale, and the ages of stage boundaries are on average 2.8 myr longer than proposed by the new Neuquén Basin radioisotopic dates.

Carnets Geol., vol. 22, no. 13, p. 619-660

Online since August 1, 2022


Priabonian non-geniculate coralline algae from the Central Carpathian Paleogene Basin
Juraj HRABOVSKÝ & Dušan STAREK

 | HTML  | PDF [8,002 KB]  | DOI: 10.2110/carnets.2022.2212

 Abstract:  Encrusting coralline algae are important rock-building organisms of the lower Priabonian limestones from the Central Carpathian Paleogene Basin. Despite the effort of early palaeontologists, former classifications lacked many diagnostic characteristics and modern taxonomic concepts, which hinders their use for modern palaeontological interpretations. The situation is further complicated as recent DNA analyses of extant coralline algae highlight the limits of the morpho-anatomical classification and identify many coralline algal genera which can also be recognized in the fossil record. Because palaeontology deals exclusively with the morpho-anatomical characteristics, a synthesis of the new discoveries in molecular phylogenetic analyses with morphology-based palaeontological classifications is necessary. Our palaeontological study based on published investigations on coralline molecular genetics enabled: 1) the identification of seventeen coralline algal morphological species grouped in six genera: Sporolithon lugeonii, Sporolithon nummuliticum, Sporolithon sp. 1, Sporolithon sp. 2, Lithothamnion camarasae, Lithothamnion cf. corallioides, Lithothamnion prascoi, Lithothamnion cf. ramosissimum, Lithothamnion roveretoi, Lithothamnion sp., Phymatolithon sp., Mesophyllum fructiferum, Mesophyllum cf. engelhartii, Mesophyllum sp., Chamberlainium lemoinei, Lithoporella melobesioides, and Lithoporella cf. minus ; 2) the description of Chamberlainium lemoinei (Miranda) comb. nov. known from the Bartonian, and 3) the identification of a unique encrusting coralline alga tentatively assigned to the genus Lithothamnion.

Carnets Geol., vol. 22, no. 12, p. 567-617

Online since August 1, 2022


A larger benthic foraminiferal zonation for the Eocene of the Caribbean and central American region
Simon F. MITCHELL, Edward ROBINSON, Ercan ÖZCAN, Mark M. JIANG & Natalie ROBINSON

 | HTML  | PDF [43,031 KB]  | DOI: 10.2110/carnets.2022.2211

 Abstract:  We have undertaken a study of the larger benthic foraminifera (LBF) of the Eocene of Jamaica that involved collecting free specimens and calibrating their occurrence against chronostratigraphy using calcareous nannofossils identified from sample splits or adjacent samples. The results have been plotted stratigraphically and allow a detailed zonation of the Eocene (14 zones) to be developed based largely on lepidocyclinids and similar forms. The zonation can be shown to be applicable to the Americas extending from northern South America, to Central America, the Caribbean and southern North America. The LBF biostratigraphy is based on the evolution of various groups. Three zones are recognized in the Ypresian, six zones in the Lutetian, three zones in the Bartonian, and two zones in the Priabonian. In order to classify the LBF we have revised the important groups used for the zonation scheme that occur in the Eocene and figure numerous examples. Our revision rearranges described genera into evolutionary, monophyletic clades to which we give the hierarchy of family and subfamily. We provide remarks on published taxa explaining how they are recognized and describe all the new taxa (two families, one subfamily, four genera and five species). The following families, genera and species are new: Butterliniana gen. nov., Helicosteginidae fam. nov., Helicostegina minor sp. nov., Helicostegina jamaicensis sp. nov., Helicostegina jeannemairae sp. nov., Pseudolepidinidae fam. nov., Orbitoininae subfam. nov., Planorbitoinella gen. nov., Polyorbitoinella gen. nov., Polyorbitoinella lilyfieldensis sp. nov., Orbitoina wrighti sp. nov., and Nephronummulites gen. nov.

Carnets Geol., vol. 22, no. 11, p. 409-565

Online since July 1, 2022


Nomenclatural Note, p. 566


Discussion of Laya et al. (2021), Dissolution of ooids in seawater-derived fluids - an example from Lower Permian re-sedimented carbonates, West Texas, USA [Sedimentology 68(6), 2671-2706]
Bruno R.C. GRANIER & Christopher G.St.C. KENDALL

 | HTML  | PDF [5,065 KB]  | DOI: 10.2110/carnets.2022.2210

 Abstract:  This discussion reassesses earlier interpretations of calcareous turbidites from the subsurface Spraberry Formation of the Happy Field (Garza County, NW Texas). It is based on routine petrographic analyses with a standard microscope. The succession of diagenetic products in this deep water setting were a little initial cementation by low magnesian calcite (LMC) and then the partial or complete leaching of both aragonite and high magnesian calcite (HMC) allochems facilitated by the presence of a residual primary intergranular porosity. This contradicts Laya et al.'s (2021) claim that cementation left no residual intergranular porosity so further leaching of the ooids would not have been possible. Instead the study made for this discussion with the same thin sections found residual primary intergranular porosity remains as evidenced by some of their photomicrographs. Most thin sections with porous grainstones have 1) collapsed molds that exhibit evidence of little initial cementation and 2) measured permeability values that range from some mD to some tens of mD. Isopachous LMC cements occur in almost all thin sections lining the margins of most intergranular pores. As these cements do not fully fill the pores, there is permeable well-connected residual primary porosity with no significant LMC cement in the secondary moldic porosity. Compaction affects the allochems and, where these are partially leached, intergranular and moldic porosities. Dissolution of aragonite (a major component) and HMC (possibly a minor component) was probably not coeval. The order of paragenetic sequence of this discussion study was: 1) LMC cementation; 2) aragonite leaching facilitated by oxidation of the organic matter in the "biocrystals" of bioclasts and oolitic cortices; 3) compactional brecciation, which was first mechanical, and then chemical causing local collapse of the molds of some of the largest pores. It was governed by cementation initially in a shallow burial diagenetic setting and then leaching whereas chemical compaction marks a slightly deeper burial diagenetic setting. The final event was marked by oil migration into the Happy Field reservoirs, freezing the calcium carbonate diagenesis. The theory of Laya et al. (2021) of the leaching of ooids in directly "seawater-derived fluids" is unsupported by the paragenetic sequence described above.

Editorial notice:  
Following the reading of a paper authored by J.C. Laya et al. in the journal Sedimentology, the authors submitted on 02-Nov-2021 a first discussion manuscript based on analogues. On 09-Nov-2021, this first manuscript was returned with harsh comments from three editors and ascribed the label "Reject & Resubmit". On 07-Mar-2022, the first author (BRCG) received a parcel with 40 thin sections to examine over a two weeks period. He was charged significant import taxes for this "scientific material". On 14-May-2022, the authors submitted a new discussion manuscript based on that same material that was studied by J.C. Laya et al. On 07-Jun-2022 this second manuscript was ascribed the label "Immediate Reject" without having any preliminary editorial reading. In the meantime, a claimant allegedly accused the first author (BRCG) of "serious breaches in academic publishing ethics" because he posted some photomicrographs of the material on a social network. On 05-Apr-2022 and again on 18-May-2022, this claimant addressed complains to the " Université de Bretagne Occidentale", an action that may be characterised as slander or defamation. Note that the authors were kindly granted the written permission to publish this discussion paper and another paper by the legitimate owner of the Happy Spraberry field, which also owns all material derived from any of their materials (e.g., cores). It looks like there is no evidence that it was the case for the other parties.

Carnets Geol., vol. 22, no. 10, p. 395-408

Online since June 19, 2022


A rare ammonite assemblage in the Romaniceras ornatissimum Zone (Middle Turonian) from the Uchaux Massif, Vaucluse, France
Francis AMÉDRO, Cyril BAUDOUIN, Gérard DELANOY, Christian DEVALQUE & Francis ROBASZYNSKI

 | HTML  | PDF [8,119 KB]  | DOI: 10.2110/carnets.2022.2209

 Abstract:  The Uchaux Massif (Vaucluse, SE France) is one of the rare places in Europe where ammonites collecting can be led from a high middle Turonian through Late Turonian. That incited Alcide d'Orbigny in 1852 to quote Uchaux as "the French type of the Turonian stage" to complement the Saumur, Tourtenay, Montrichard and Tours localities mentionned in 1842 when the stage was created. In 2014, the monograph by Robaszynski et al. synthetized and actualized the informations available on the litho- and biostratigraphy of the Turonian from the Uchaux Massif. More recently, a new outcrop at Mondragon, in a place named Prés Morel, exposes the whole carbonate siltstones with Spongia of the Peyras Member (UL3). Were collected : Lewesiceras peramplum (Mantell, 1822), Romaniceras (Romaniceras) marigniacum Amédro & Châtelier, 2020, R. (Yubariceras) ornatissimum (Stoliczka, 1864), R. (Y.) kanei Jones, 1938, Collignoniceras woollgari regulare (Haas, 1946), C. carolinum (Orbigny, 1841), C. papale (Orbigny, 1841), C. turoniense (Orbigny, 1841) and a new species of Collignoniceras : C. rhodanicum Amédro, Baudouin & Delanoy sp. nov. This assemblage, unprecedented in the studied area, is characteristic of the Romaniceras ornatissimum Zone which is the third of the four ammonite zones of the middle Turonian (Tm 3). At the top of this third zone, the surprise was to find the Romaniceras marigniacum bio-horizon defined in 2020 in the southern part of the Paris Basin at the top of the Tuffeau de Bourré and at the base of the Tuffeau Jaune de Touraine. Moreover, we now think that the Peyras Member has to be fully assigned to the Romaniceras ornatissimum Zone. Lastly, the assemblage includes a rich population of Collignoniceras carolinum (24 specimens), the most important known to-day over the world. All these ammonites allow to know the spectrum of their morphological variations and show a dimorphism through the existence of micro- and macroconchs.

Carnets Geol., vol. 22, no. 9, p. 333-393

Online since July 1, 2022


The Kalkowsky Project - Chapter IV. Case study of the Happy Spraberry oil reservoirs in NW Texas (with a micropaleontologic and biostratigraphic supplement): Collapsed molds should not be treated as a category of distorted ooids
Bruno R.C. GRANIER, Christopher G.St.C. KENDALL & Daniel VACHARD

 | HTML  | PDF [6,180 KB]  | DOI: 10.2110/carnets.2022.2208

 Abstract:  The subsurface upper Spraberry Formation in NW Texas is dominantly composed of calcareous turbidites and debris-flows. The petrographic analysis of its porous grain-supported fabrics revealed the presence of controversial superimposed compaction fabrics, sometimes referred to as "distorted ooids". Based on the paragenetic sequence, it is demonstrated that these allochems were not distorted. In fact, the related zigzag and silcrow (§) patterns result from the collapse of molds, either oomolds or biomolds, in response to mechanical compaction of the fragile framework made up of isopachous Low-Mg Calcite cement surrounding these empty molds. As a side finding, this stratigraphic unit, which was said to be late Kungurian in age, is proved to be nearly 7 millions of year older.

Carnets Geol., vol. 22, no. 8, p. 311-332

Online since June 2, 2022


Taxonomy of the fossil calcareous algae: Revision of genera Physoporella Steinmann and Oligoporella Pia (Dasycladales)
Tonći GRGASOVIĆ

 | HTML  | PDF [31,142 KB]  | DOI: 10.2110/carnets.2022.2207

 Abstract:  The taxonomic classification and mutual distinction of the genera Physoporella Steinmann and Oligoporella Pia (Dasycladales, green algae) have proven problematic and that has impeded their use in stratigraphy and other studies. The presence of single whorls of piriform laterals in Physoporella and double whorls in Oligoporella is considered as the main characteristic that separates these genera. According to that, diagnoses of genera and all species and varieties are changed or supplemented, and detailed descriptions are given. For this purpose the type-material from Pia's collection was re-examined and its redocumentation and reinterpretation performed. Additional information was obtained from abundant material from Croatia (Ivanščica Mt, Medvednica Mt, Žumberak Mt, Lika, Dalmatia). Only a few taxa were examined based on literature data. For all species and varieties reconstructions are given. Taxa from the Permian of East Asia are only briefly described. Among the investigated taxa, some of them have a structure that significantly differs from that present in the type species of the genera Physoporella and Oligoporella. They are separated into two new genera Ardeiporella and Neophysoporella. The revised genera Physoporella and Oligoporella, together with the newly established ones, give a clearer picture of phylogenetic relations.

Carnets Geol., vol. 22, no. 7, p. 171-310

Online since June 4, 2022


The report of a rare deformed eagle ray (Myliobatiformes: Myliobatidae) tooth plate from the Neogene of Calvert Cliffs, Maryland, U.S.A.
Stephen J. GODFREY, David J. BOHASKA & John MAISEY

 | HTML  | PDF [937 KB]  | DOI: 10.2110/carnets.2022.2206

 Abstract:  An isolated and deformed lower tooth plate of an eagle ray (Aetomylaeus sp., Myliobatidae, Myliobatiformes) is reported herein from the Miocene deposits along Calvert Cliffs, Maryland, U.S.A. Deformed myliobatid tooth plates like this, either fossil or modern, are exceedingly rare. All medial teeth are deformed/skewed such that the right side of each tooth forms an angle of about 10 degrees to the transverse axis of the dental plate. The skewed abnormal form of the teeth in USNM PAL 726325 is not thought to be the result of modern or taphonomic deformation. Rather, the deformity exhibited by USNM PAL 726325 gives every indication that successive similarly deformed teeth came about as a result of a persistent anatomical deformity of the dental lamina. From the consistency in the deformed shape of each tooth, it would appear as though the dental lamina retained this anomalous shape at least throughout the time represented by the age of the tooth plate. If this interpretation is correct, the deformity was not fatal and did not significantly impair the functionality of the tooth pavement over a protracted part (or all) of the individual's life span.

Carnets Geol., vol. 22, no. 6, p. 161-169

Online since May 10, 2022


The Kalkowsky Project - Chapter III. Significance of primary radial fabrics associated with ancient partly leached or recrystallized calcareous ooids
Bruno R.C. GRANIER & Philippe LAPOINTE

 | HTML  | PDF [1,851 KB]  | DOI: 10.2110/carnets.2022.2205

 Abstract:  Calcitic ooids and bothryoids from the Yacoraite Formation in the provinces of Jujuy and Salta (Argentina) display radial fabrics pointing to their primarily high-Mg calcite (HMC) nature. The present publication documents some specimens that are partly or fully leached or recrystallized, which raises fundamental questions about the validity of some concepts, such as the very existence of the so-called "two-phase"/"bimineralic" ooids. It is assumed here that the organic content in the oolitic cortices (and, subsequently, its degree of oxidation) is the key to explaining some differential diagenetic alterations.

Carnets Geol., vol. 22, no. 5, p. 149-160

Online since March 4, 2022


Adult morphologies of Puzosia quenstedti (Parona & Bonarelli, 1897) (Ammonoidea, Desmoceratidae) in the Albian of the South-East of France. Taxonomic implications
Jean-Louis Latil LATIL, Gérard DELANOY & Pierre DELATTRE

 | HTML  | PDF [5,643 KB]  | DOI: 10.2110/carnets.2022.2204

 Abstract:  Several adult specimens belonging to the genus Puzosia Bayle, 1878, were collected in the Albian of Lieuche (Alpes-Maritimes, France). Comparison with material from the condensed Albian levels of La Balme de Rencurel (Isère, France), in particular those described and figured by Jacob (1908), has highlighted a morphological link between the adult forms from Lieuche and the incomplete specimens from the condensed levels of the Lower-Middle Albian of south-eastern France and to identify them as Puzosia quenstedti (Parona & Bonarelli, 1897). These new details on the ontogenetic development of this species also allow new perspectives in the taxonomic treatment of Albian Puzosia species. A modified diagnosis of Puzosia quenstedti is proposed.
The presence of Douvilleiceras sp. juv. aff. D. mammillatum (Schlotheim, 1813) in superimposed overlying levels allows assignation of a Lower Albian (Douvilleiceras mammillatum Superzone) to a basal Middle Albian age (Hoplites dentatus Zone).

Carnets Geol., vol. 22, no. 4, p. 119-147

Online since February 28, 2022


The Kalkowsky Project - Chapter II. Wobbly ooids in a stromatolite from the Yacoraite Formation (Argentina)
Bruno R.C. GRANIER & Philippe LAPOINTE

 | HTML  | PDF [1,375 KB]  | DOI: 10.2110/carnets.2022.2203

 Abstract:  Eccentric ooids are described from a brackish Maastrichtian paleolake in NW Argentina. The first report of such atypical coated grains was from marine Upper Jurassic strata in SE Poland. Because their growth pattern is not likely to be confused with that of other "eccentric" ooids, such as asymmetric ooids, hiatus ooids, half-moon ooids, or "broken" ooids, it is suggested here to name them "wobbly ooids".

Carnets Geol., vol. 22, no. 3, p. 111-117

Online since February 15, 2022


The genera Roloboceras Casey, 1954, and Megatyloceras Humphrey, 1949 (Ammonoidea, Ancyloceratina, Douvilleiceratidae), from the Lower Aptian of Ardèche (SE France) - Taxonomic and biostratigraphic implications
Gérard DELANOY, Cyril BAUDOUIN, Antoine PICTET, Josep MORENO-BEDMAR, Camille FRAU & Bertrand MATRION

 | HTML  | PDF [11,947 KB]  | DOI: 10.2110/carnets.2022.2202

 Abstract:  The Lower Aptian marine deposits from southern Ardèche (South-East of France) yield a rich ammonite fauna of the sub-family Roloboceratinae Casey, 1961, which dates the upper Deshayesites forbesi Zone (Roloboceras hambrovi Subzone pro parte ?). The systematic study of this Roloboceratinae fauna has improved our knowledge of Megatyloceras coronatum Rouchadzé, 1933, type species of Megatyloceras Humphrey, 1949, as well as a better understanding of the genus thanks to the examination of the species from the Anglo-Paris Basin. A new species, M. leteilensis sp. nov. is introduced, and a description of M. transiens Casey, 1961, provided, with clarifications on its possible stratigraphic position. This study also establishes that the "species" Megatyloceras ricordeanum (Orbigny, 1850) represents only a growth stage shared by several species of Megatyloceras which is doubtfully a true taxon and must, therefore, be considered as a nomen dubium. The hypothesis of sexual dimorphism in Roloboceras Casey, 1954, and Megatyloceras is advanced. The study of this Roloboceratinae fauna highlights their heterogeneous distribution throughout Lower Aptian deposits of Ardèche, showing a direct correlation with bathymetric range. The biostratigraphical distribution of both genera on the Languedoc platform shows that Roloboceras is present from the uppermost C2 segment to the C4 segment of the stable carbon-isotope record, while Megatyloceras is limited to the middle C4 segment up to the lowermost C6 segment. Both genera coexist during the C4 segment.

Carnets Geol., vol. 22, no. 2, p. 7-109

Online since February 17, 2022


Nomenclatural Note, p. 110


Comments on a small sabretooth cat in the Abismo Ponta de Flecha Cave, Vale do Ribeira, southeastern Brazil
Artur CHAHUD

 | HTML  | PDF [448 KB]  | DOI: 10.2110/carnets.2022.2201

 Abstract:  Vale do Ribeira, in southeastern Brazil, is known for its many caves that contain osteological material, including remains that have been referred to several extinct species. The sabertooth cat Smilodon populator was a large predator that inhabited South America during the Quaternary. A specimen that is represented in the Abismo Ponta de Flecha Cave by small forelimb bones (metacarpals and phalanges) is commented here. The metacarpals display morphological characteristics of S. populator, but are smaller than those of S. fatalis and larger than those of S. gracilis. This specimen is amongst the smallest ever found specimen of S. populator and is comparable in size to an adult lion.

Carnets Geol., vol. 22, no. 1, p. 1-6

Online since January 17, 2022


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