The northern Montagne Noire possesses one of the most complete Cambrian-Lower Ordovician successi... more The northern Montagne Noire possesses one of the most complete Cambrian-Lower Ordovician successions of West Gondwana. The strata are poorly fossiliferous, metamorphized and disturbed by Variscan tectonism, and their stratigraphic nomenclature dramatically multiplied by the designation of numerous informal units exclusively identifiable in their own Variscan thrust slices and nappes. This paper presents an updated revision oflithostratigraphic units and volcanic complexes. Special attention is given to crosscutting relationships of the latter and the setting and age offossiliferous phosphorites, such as the Walsonella crosbyi-bearing phosphatic limestones of the Marcou Formation. This mollusc is key to defining in the next future the Global Standard Cambrian (Terreneuvian) Stage I/Stage2 boundary. The absence of Ca domi an tectono-therrnal events is documented by meso- and microstructural and metamorphic analyses.
carbonate bed of the Pardailhan Formation,
early Cambrian, southern Montagne Noire (southern
Fran... more carbonate bed of the Pardailhan Formation, early Cambrian, southern Montagne Noire (southern France), provided microfossils such as Hyolithellus sp., Torellella cf. mutila and Torellella sp. along with numerous disarticulated pieces of composite skeletons such as valves of the brachiopod Eoobolus priscus and of the bradoriid Monceretia erisylvia, and chancelloriid sclerites (Chancelloria sp.). The assemblage also furnished a rich set of sclerites from the tommotiid Kelanella altaica. Five morphological variations of the latter have been identified. The presence of concentric ribs formed by distal inflation of selected shell laminae in Kelanella supports its assignment to the camenellans. More particularly, the presence of transverse structures within the internal cavity (septa) of Kelanella suggests a close relationship with the Lapworthellidae. However, the latter differ from Kelanella by the continuous morphological variation along their scleritome which is also composed of simple conical elements with uniform ornamentation. Several forms of Kelanella are similar to mitral and sellate sclerites of Camenella, whereas some other forms are comparable to Kennardia. The new material suggests that Kelanella occupies a transitional position between Lapworthellidae and the grouping of Tommotiidae and Kennardiidae. Such a phylogenetic position also implies that the number of sclerite morphotypes tends to decrease within the camenellan scleritome during evolution.
tThe Montagne Noire (southern France) possesses one of the most complete Cambrian successions int... more tThe Montagne Noire (southern France) possesses one of the most complete Cambrian successions inthe western peri-Gondwana margin and might provide a good stratigraphic reference for both regionalcharts and international correlations. However, to date, the lower Cambrian succession of the northernMontagne Noire has been supposed to be devoid of biostratigraphically significant fossils. The complextectonostratigraphic framework of the area (a range divided into Axial Zone, northern and southernMontagne Noire) exacerbated problems related to regional correlations and palaeogeographic recon-structions. As a result, the chronostratigraphic context of the lower Cambrian of northern MontagneNoire is still uncertain and stratigraphic reports have broadly relied on putative lithostratigraphic corre-lations with the southern Montagne Noire. The purpose of this study is to characterise, for the first time,the fossil record of carbonate beds and lenses of the northern Montagne Noire occurring at the top ofthe siliciclastic-dominated Marcory Formation, in order to provide regional bio- and chronostratigraphicconstraints on lower Cambrian strata. Moreover, this study is aimed at improving international chronos-tratigraphic correlation. Carbonate beds and lenses cropping out along the Orque Cliff, in the Mélaguesthrust slice, were investigated. They yielded a faunal assemblage constituted of molluscs (Igorella cf. ungu-lata and Igorella moncereti n. sp.), hyoliths (Conotheca brevica), chancelloriids (Archiasterella cf. pentactinaand Allonnia sp.) and tommotiids (Lapworthella rete). L. rete is recorded in upper Meishucunian (CambrianStage 3) strata of the Yangtze Platform (South China) where it is used as index fossil of the Cambrian Stage3 Sinosachites flabelliformis–Tannuolina zhangwentangi Assemblage Zone. Therefore, the presence of thistommotiid provides evidence that the studied carbonate beds and lenses are Cambrian Age 3 (Atdabanianaccording to the Siberian chart). The upper part of the Marcory Formation in the Mélagues slice, dated asCambrian Stage 3, might represent a lateral equivalent of the mixed (carbonate-siliciclastic) PardailhanFormation defined in the southern Montagne Noire.
Abstract The Lower Cambrian Pardailhan Formation of the Montagne Noire (Southern France) has yiel... more Abstract The Lower Cambrian Pardailhan Formation of the Montagne Noire (Southern France) has yielded a diverse fossil assemblage including bivalved arthropods (the bradoriids Monceretia erisylvia gen. et sp. nov., Cambria danvizcainia sp. nov. and ...
The northern Montagne Noire possesses one of the most complete Cambrian-Lower Ordovician successi... more The northern Montagne Noire possesses one of the most complete Cambrian-Lower Ordovician successions of West Gondwana. The strata are poorly fossiliferous, metamorphized and disturbed by Variscan tectonism, and their stratigraphic nomenclature dramatically multiplied by the designation of numerous informal units exclusively identifiable in their own Variscan thrust slices and nappes. This paper presents an updated revision oflithostratigraphic units and volcanic complexes. Special attention is given to crosscutting relationships of the latter and the setting and age offossiliferous phosphorites, such as the Walsonella crosbyi-bearing phosphatic limestones of the Marcou Formation. This mollusc is key to defining in the next future the Global Standard Cambrian (Terreneuvian) Stage I/Stage2 boundary. The absence of Ca domi an tectono-therrnal events is documented by meso- and microstructural and metamorphic analyses.
carbonate bed of the Pardailhan Formation,
early Cambrian, southern Montagne Noire (southern
Fran... more carbonate bed of the Pardailhan Formation, early Cambrian, southern Montagne Noire (southern France), provided microfossils such as Hyolithellus sp., Torellella cf. mutila and Torellella sp. along with numerous disarticulated pieces of composite skeletons such as valves of the brachiopod Eoobolus priscus and of the bradoriid Monceretia erisylvia, and chancelloriid sclerites (Chancelloria sp.). The assemblage also furnished a rich set of sclerites from the tommotiid Kelanella altaica. Five morphological variations of the latter have been identified. The presence of concentric ribs formed by distal inflation of selected shell laminae in Kelanella supports its assignment to the camenellans. More particularly, the presence of transverse structures within the internal cavity (septa) of Kelanella suggests a close relationship with the Lapworthellidae. However, the latter differ from Kelanella by the continuous morphological variation along their scleritome which is also composed of simple conical elements with uniform ornamentation. Several forms of Kelanella are similar to mitral and sellate sclerites of Camenella, whereas some other forms are comparable to Kennardia. The new material suggests that Kelanella occupies a transitional position between Lapworthellidae and the grouping of Tommotiidae and Kennardiidae. Such a phylogenetic position also implies that the number of sclerite morphotypes tends to decrease within the camenellan scleritome during evolution.
tThe Montagne Noire (southern France) possesses one of the most complete Cambrian successions int... more tThe Montagne Noire (southern France) possesses one of the most complete Cambrian successions inthe western peri-Gondwana margin and might provide a good stratigraphic reference for both regionalcharts and international correlations. However, to date, the lower Cambrian succession of the northernMontagne Noire has been supposed to be devoid of biostratigraphically significant fossils. The complextectonostratigraphic framework of the area (a range divided into Axial Zone, northern and southernMontagne Noire) exacerbated problems related to regional correlations and palaeogeographic recon-structions. As a result, the chronostratigraphic context of the lower Cambrian of northern MontagneNoire is still uncertain and stratigraphic reports have broadly relied on putative lithostratigraphic corre-lations with the southern Montagne Noire. The purpose of this study is to characterise, for the first time,the fossil record of carbonate beds and lenses of the northern Montagne Noire occurring at the top ofthe siliciclastic-dominated Marcory Formation, in order to provide regional bio- and chronostratigraphicconstraints on lower Cambrian strata. Moreover, this study is aimed at improving international chronos-tratigraphic correlation. Carbonate beds and lenses cropping out along the Orque Cliff, in the Mélaguesthrust slice, were investigated. They yielded a faunal assemblage constituted of molluscs (Igorella cf. ungu-lata and Igorella moncereti n. sp.), hyoliths (Conotheca brevica), chancelloriids (Archiasterella cf. pentactinaand Allonnia sp.) and tommotiids (Lapworthella rete). L. rete is recorded in upper Meishucunian (CambrianStage 3) strata of the Yangtze Platform (South China) where it is used as index fossil of the Cambrian Stage3 Sinosachites flabelliformis–Tannuolina zhangwentangi Assemblage Zone. Therefore, the presence of thistommotiid provides evidence that the studied carbonate beds and lenses are Cambrian Age 3 (Atdabanianaccording to the Siberian chart). The upper part of the Marcory Formation in the Mélagues slice, dated asCambrian Stage 3, might represent a lateral equivalent of the mixed (carbonate-siliciclastic) PardailhanFormation defined in the southern Montagne Noire.
Abstract The Lower Cambrian Pardailhan Formation of the Montagne Noire (Southern France) has yiel... more Abstract The Lower Cambrian Pardailhan Formation of the Montagne Noire (Southern France) has yielded a diverse fossil assemblage including bivalved arthropods (the bradoriids Monceretia erisylvia gen. et sp. nov., Cambria danvizcainia sp. nov. and ...
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Papers by Eric Monceret
Gondwana. The strata are poorly fossiliferous, metamorphized and disturbed by Variscan tectonism, and their stratigraphic nomenclature
dramatically multiplied by the designation of numerous informal units exclusively identifiable in their own Variscan thrust slices and
nappes. This paper presents an updated revision oflithostratigraphic units and volcanic complexes. Special attention is given to crosscutting
relationships of the latter and the setting and age offossiliferous phosphorites, such as the Walsonella crosbyi-bearing phosphatic
limestones of the Marcou Formation. This mollusc is key to defining in the next future the Global Standard Cambrian (Terreneuvian)
Stage I/Stage2 boundary. The absence of Ca domi an tectono-therrnal events is documented by meso- and microstructural and metamorphic
analyses.
early Cambrian, southern Montagne Noire (southern
France), provided microfossils such as Hyolithellus sp.,
Torellella cf. mutila and Torellella sp. along with numerous
disarticulated pieces of composite skeletons such as valves
of the brachiopod Eoobolus priscus and of the bradoriid
Monceretia erisylvia, and chancelloriid sclerites (Chancelloria
sp.). The assemblage also furnished a rich set of sclerites
from the tommotiid Kelanella altaica. Five morphological
variations of the latter have been identified. The presence
of concentric ribs formed by distal inflation of selected
shell laminae in Kelanella supports its assignment to the
camenellans. More particularly, the presence of transverse
structures within the internal cavity (septa) of Kelanella
suggests a close relationship with the Lapworthellidae.
However, the latter differ from Kelanella by the continuous
morphological variation along their scleritome which
is also composed of simple conical elements with uniform
ornamentation. Several forms of Kelanella are similar to
mitral and sellate sclerites of Camenella, whereas some
other forms are comparable to Kennardia. The new material
suggests that Kelanella occupies a transitional position
between Lapworthellidae and the grouping of Tommotiidae
and Kennardiidae. Such a phylogenetic position also
implies that the number of sclerite morphotypes tends to
decrease within the camenellan scleritome during
evolution.
Gondwana. The strata are poorly fossiliferous, metamorphized and disturbed by Variscan tectonism, and their stratigraphic nomenclature
dramatically multiplied by the designation of numerous informal units exclusively identifiable in their own Variscan thrust slices and
nappes. This paper presents an updated revision oflithostratigraphic units and volcanic complexes. Special attention is given to crosscutting
relationships of the latter and the setting and age offossiliferous phosphorites, such as the Walsonella crosbyi-bearing phosphatic
limestones of the Marcou Formation. This mollusc is key to defining in the next future the Global Standard Cambrian (Terreneuvian)
Stage I/Stage2 boundary. The absence of Ca domi an tectono-therrnal events is documented by meso- and microstructural and metamorphic
analyses.
early Cambrian, southern Montagne Noire (southern
France), provided microfossils such as Hyolithellus sp.,
Torellella cf. mutila and Torellella sp. along with numerous
disarticulated pieces of composite skeletons such as valves
of the brachiopod Eoobolus priscus and of the bradoriid
Monceretia erisylvia, and chancelloriid sclerites (Chancelloria
sp.). The assemblage also furnished a rich set of sclerites
from the tommotiid Kelanella altaica. Five morphological
variations of the latter have been identified. The presence
of concentric ribs formed by distal inflation of selected
shell laminae in Kelanella supports its assignment to the
camenellans. More particularly, the presence of transverse
structures within the internal cavity (septa) of Kelanella
suggests a close relationship with the Lapworthellidae.
However, the latter differ from Kelanella by the continuous
morphological variation along their scleritome which
is also composed of simple conical elements with uniform
ornamentation. Several forms of Kelanella are similar to
mitral and sellate sclerites of Camenella, whereas some
other forms are comparable to Kennardia. The new material
suggests that Kelanella occupies a transitional position
between Lapworthellidae and the grouping of Tommotiidae
and Kennardiidae. Such a phylogenetic position also
implies that the number of sclerite morphotypes tends to
decrease within the camenellan scleritome during
evolution.