The Llucmajor platform on southern Mallorca Island (Spain) is one of the best-exposed Miocene sha... more The Llucmajor platform on southern Mallorca Island (Spain) is one of the best-exposed Miocene shallow-water carbonate platforms known in the world. Up to 90 m vertical sea cliffs provide a clean, continuous and detailed 3D view of the facies architecture and continuous cores from fifty-two water wells, affording information to interpret the 3D architecture of this 20 km-wide and only slightly deformed carbonate platform. Forty years of research on the Llucmajor platform provided insights into how the mutual interaction of biological and physical processes control the type of carbonate production and sediment dynamics which, along with changes in sea-level, determine the facies stacking patterns and the distribution of internal heterogeneities. Moreover, the ‘modern character’ of the carbonate-producing biota permits to capture the response of the carbonate system to changing ecological and oceanographic conditions. Although learnings from the Llucmajor platform do not apply to older platforms, it is this process-product type of analysis that can be applied to carbonate systems of all ages. Thus through this field guide, two carbonate factories working out of phase and with a non-linear response to sea-level changes are identified. A shallow-water euphotic (well lit) production (corals, red and green calcareous algae and associated heterozoan biota) predominated during rising sea-level when linear reefal rims grading to broad lagoons expanded and increased production and the sediment shed-off from these reef-lagoon systems built-out thick slopes. A deeper oligophotic (low light) factory expanded during the lowstands of sea-level when the light reached the basin floor; red algae, larger benthic foraminifers and molluscs were the prime producers. The Llucmajor platform grew up during the late Miocene, through the transition from greenhouse to icehouse climate that characterised the late Cenozoic. Its building blocks occur hierarchically stacked in response to the sea-level cyclicity. At the bed scale, the sigmoids consist of a lagoonal bed passing successively into sigmoidal reef core and then into slope clinobed and basinal deposits and bounded by an erosion surface onto the lagoon and reef and its correlative conformity basinward. Sigmoids stack in sets of sigmoids, these in cosets of sigmoids and these last in megasets, all of them fitting the characteristics of a depositional sequence when the genetic processes are analysed. Departures from the sequence model rely on the inter-dependence between depth gradient, the type of carbonate-producing biota and the ranges of sea-level cyclicity. Through the visit to a series of selected outcrops, this field guide offers a comprehensive assessment of the Llucmajor reef-rimmed shelf from the basin to the coral-dominated reefal margin and across the open-lagoon to restricted lagoon that defined the shelf top. The itinerary focusses on numerous topics and at different scales, from the study of discrete rock bodies to km-wide outcrop windows resembling high-resolution seismic profiles. The field guide integrates facies analysis, stratal architecture and distinct diagenetic features such as extensive secondary porosity after the dissolution of aragonitic components and pervasive dolomitization. Impressive sub-vertical collapse structures were produced by karstic dissolution during lowstands of sea-level and gravitational collapse of the roof complete the suite of diagenetic overprint. Altogether, the depositional and diagenetic attributes of the Llucmajor platform reveal a complex and highly heterogeneous carbonate system that is used as outcrop analogue for numerous Miocene carbonate reservoirs across the world.
Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbo... more Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbonate production and sedimentation across shallow‐water and nearshore environments, sustaining a prolific carbonate factory and contributing to sediment accumulation through the combination of baffling and trapping effects. Most reported Palaeogene seagrass occurrences developed in oligo−mesotrophic shallow warm‐water habitats and are characterized by distinct associations of small and larger benthic foraminifers adapted to low terrigenous influence. This study describes a number of seagrass episodes interbedded in the Bartonian (middle Eocene) of San Fausto–Lazkua area (Navarra region, North Spain), within a nearshore to inner‐ramp succession that, in spite of being deposited under general transgressive conditions, was highly influenced by terrigenous supply from the adjacent land. Up to twelve different seagrass bed intervals occur interbedded in a cyclical manner with high‐energy nearshore siliciclastics and inner ramp bioclastic carbonates rich in mesophotic−oligophotic foraminifers and heterozoan biota (red algae, echinoderms, bryozoans). Seagrass deposits exhibit typical unsorted textures, abundant bioturbation and moderate to high terrigenous content, and comprise a characteristic skeletal association of epiphytic foraminifers, red algae and, most particularly, of abundant encrusting acervulinids, commonly with distinct hooked and tubular growth forms. This abundance of suspension‐feeders relative to autotrophs and mixotrophs may be indicative of temperate waters, although the taxonomic diversity of the foraminiferal assemblages in both seagrass and non‐seagrass embedding deposits supports the interpretation of shallow, warm‐water conditions. The studied seagrass deposits provide evidence that high siliciclastic supply and associated nutrient input may determine the occurrence of temperate‐like seagrass deposits in warm‐water settings, analogous to extensive heterozoan carbonate production in modern shallow‐tropical environments. Thus, the identification and correct interpretation of past seagrass‐vegetated environments are crucial for reconstructing palaeoecological conditions in ancient shallow‐marine environments. Therefore, in comparison with carbonate‐dominated environments, the mixed terrigenous−carbonate seagrass deposits are volumetrically less important, presenting a more irregular, patchy distribution, and a skeletal assemblage dominated by heterotrophs, regardless of the water temperature.
LA PRESENTE TESIS SE HA CENTRADO EN EL ANALISIS ESTRATIGRAFICO, SEDIMENTOLOGICO Y PALEOGEOGRAFICO... more LA PRESENTE TESIS SE HA CENTRADO EN EL ANALISIS ESTRATIGRAFICO, SEDIMENTOLOGICO Y PALEOGEOGRAFICO DEL INTERVALO MAASTRICHTIENSE SUPERIOR-PALEOCENO- ILERDIENSE INFERIOR (MPI) DE LA REGION VASCO- CANTABRICA. DICHO ANALISIS SE HA REALIZADO BAJO UN ENFOQUE DE ESTRATIGRAFIA SECUENCIAL, HABIENDOSE RECONOCIDO UN TOTAL DE 8 SECUENCIAS DEPOSICIONALES DE VALOR REGIONAL (ASOCIABLES A CAMBIOS RELATIVOS DEL NIVEL DEL MAR DE TERCER ORDEN), CUYA EDAD SE HA CALIBRADO CON EXACTITUD MEDIANTE FORAMINIFEROS PLANCTONICOS, MACROFORAMINIFEROS Y MAGNETOESTRATIGRAFIA. A UNA ESCALA MAYOR, SE HA CONSTATADO QUE EL MPI FORMA PARTE DE UN CICLO TRANSGRESIVO-REGRESIVO DE SEGUNDO ORDEN, DESARROLLADO EN RESPUESTA A LA EVOLUCION TECTO-SEDIMENTARIA EXPERIMENTADA POR LA REGION. EL MPI CONSTITUYE, EN CONCRETO, EL HEMICICLO TRANSGRESIVO DE DICHA UNIDAD MAYOR. A SU VEZ, DENTRO DE EL, SE DEFINEN TRES FASES EVOLUTIVAS (T1, T2 Y T3), CARACTERIZADAS SOBRE TODO POR EL DESARROLLO DE UN DISPOSITIVO SEDIMENTARIO DIFERENCIADO Y POR EL MODO DE APILAMIENTO DE LAS SECUENCIAS. LAS 8 SECUENCIAS DEPOSICIONALES ESTAN PRINCIPALMENTE CONSTITUIDAS POR MATERIALES CARBONATADOS, PERO INCLUYEN TAMBIEN DEPOSITOS DE NATURALEZA SILICICLASTICA. EL ESTUDIO SEDIMENTOLOGICO DE TODOS ELLOS, COMBINADO CON LAS LABORES DE CARTOGRAFIA Y CORRELACION, HA PERMITIDO RECONOCER TODA UNA GAMA DE DOMINIOS DE SEDIMENTACION: UNA PLATAFORMA CARBONATADA SOMERA, DENTRO DE LA CUAL ESTAN REPRESENTADOS AMBIENTES Y SUBAMBIENTES DESDE CONTINENTALES Y/O TRANSICIONALES HASTA MARINO ABIERTOS; UNA ZONA DE TRANSICION PLATAFORMA-CUENCA, COMPUESTA A SU VEZ POR UN TALUD DE CARACTER FUNDAMENTALMENTE EROSIVO, Y UN PIE DE TALUD DEFINIDO POR ACUMULACIONES DE MATERIALES RESEDIMENTADOS DE PROCEDENCIA SOMERA; Y POR ULTIMO, UN AREA DE CUENCA PROFUNDA, DONDE ASIMISMO SE DEFINEN DOS SISTEMAS BIEN DIFERENCIADOS: UN FONDO DE CUENCA CARACTERIZADO POR SEDIMENTACION DE CARACTER PELAGICO Y/O HEMIPELAGICO, Y UN CANAL SUBMARINO PROFUNDO, RELLENA
The carbonate factories, their controlling factors and their palaeoecological and sedimentologica... more The carbonate factories, their controlling factors and their palaeoecological and sedimentological signals recorded in sedimentary successions are key elements for understanding the evolution of carbonate platform systems. Luis Pomar has dedicated most of his academic life to the study of carbonate rocks and carbonate factories. The idea for this special issue to celebrate Pomar’s career arose during a session at the 34th International Association of Sedimentologists meeting held in Rome, entitled ‘Understanding carbonate factories through palaeoecological and geochemical signals’. The proposal encountered great response among participants, and additional contributions followed an email invitation to other specialists. This issue contains a variety of papers on carbonate sedimentology and carbonate factories. Here, an introduction that contextualizes the papers and key concepts discussed in this thematic issue is provided. It reviews Luis Pomar’s major achievements in carbonate sedimentology and discusses the evolution of the concept of the carbonate factory and the series of palaeoecological and sedimentological signals used to characterize the wide spectrum of carbonate depositional systems found in the natural world.
In recent years, the discovery of isolated teeth from the Late Cretaceous (Campanian-Maastrichtia... more In recent years, the discovery of isolated teeth from the Late Cretaceous (Campanian-Maastrichtian) of the Basque-Cantabrian Region, in the north of the Iberian Peninsula, has permitted to recognise at least four different mosasaurid taxa in several sites of Alava and Condado de Treviño: Mosasaurus lemonnieri, Prognathodon solvayi, Platecarpus cf. ictericus and Tylosaurus sp. A new specimen, which consists of a fragment of skull with articulated portions of the maxilla and prefrontal, from the Campanian of Navarre is described here. This material is assigned to Prognathodon cf. sectorius on the basis of dental features. It constitutes the only cranial remain and the most significant mosasaurid fragment known to date in the Iberian Peninula. P. sectorius was previously recorded from the Maastrichtian of New-Jersey and The Netherlands.
The Llucmajor platform on southern Mallorca Island (Spain) is one of the best-exposed Miocene sha... more The Llucmajor platform on southern Mallorca Island (Spain) is one of the best-exposed Miocene shallow-water carbonate platforms known in the world. Up to 90 m vertical sea cliffs provide a clean, continuous and detailed 3D view of the facies architecture and continuous cores from fifty-two water wells, affording information to interpret the 3D architecture of this 20 km-wide and only slightly deformed carbonate platform. Forty years of research on the Llucmajor platform provided insights into how the mutual interaction of biological and physical processes control the type of carbonate production and sediment dynamics which, along with changes in sea-level, determine the facies stacking patterns and the distribution of internal heterogeneities. Moreover, the ‘modern character’ of the carbonate-producing biota permits to capture the response of the carbonate system to changing ecological and oceanographic conditions. Although learnings from the Llucmajor platform do not apply to older platforms, it is this process-product type of analysis that can be applied to carbonate systems of all ages. Thus through this field guide, two carbonate factories working out of phase and with a non-linear response to sea-level changes are identified. A shallow-water euphotic (well lit) production (corals, red and green calcareous algae and associated heterozoan biota) predominated during rising sea-level when linear reefal rims grading to broad lagoons expanded and increased production and the sediment shed-off from these reef-lagoon systems built-out thick slopes. A deeper oligophotic (low light) factory expanded during the lowstands of sea-level when the light reached the basin floor; red algae, larger benthic foraminifers and molluscs were the prime producers. The Llucmajor platform grew up during the late Miocene, through the transition from greenhouse to icehouse climate that characterised the late Cenozoic. Its building blocks occur hierarchically stacked in response to the sea-level cyclicity. At the bed scale, the sigmoids consist of a lagoonal bed passing successively into sigmoidal reef core and then into slope clinobed and basinal deposits and bounded by an erosion surface onto the lagoon and reef and its correlative conformity basinward. Sigmoids stack in sets of sigmoids, these in cosets of sigmoids and these last in megasets, all of them fitting the characteristics of a depositional sequence when the genetic processes are analysed. Departures from the sequence model rely on the inter-dependence between depth gradient, the type of carbonate-producing biota and the ranges of sea-level cyclicity. Through the visit to a series of selected outcrops, this field guide offers a comprehensive assessment of the Llucmajor reef-rimmed shelf from the basin to the coral-dominated reefal margin and across the open-lagoon to restricted lagoon that defined the shelf top. The itinerary focusses on numerous topics and at different scales, from the study of discrete rock bodies to km-wide outcrop windows resembling high-resolution seismic profiles. The field guide integrates facies analysis, stratal architecture and distinct diagenetic features such as extensive secondary porosity after the dissolution of aragonitic components and pervasive dolomitization. Impressive sub-vertical collapse structures were produced by karstic dissolution during lowstands of sea-level and gravitational collapse of the roof complete the suite of diagenetic overprint. Altogether, the depositional and diagenetic attributes of the Llucmajor platform reveal a complex and highly heterogeneous carbonate system that is used as outcrop analogue for numerous Miocene carbonate reservoirs across the world.
Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbo... more Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbonate production and sedimentation across shallow‐water and nearshore environments, sustaining a prolific carbonate factory and contributing to sediment accumulation through the combination of baffling and trapping effects. Most reported Palaeogene seagrass occurrences developed in oligo−mesotrophic shallow warm‐water habitats and are characterized by distinct associations of small and larger benthic foraminifers adapted to low terrigenous influence. This study describes a number of seagrass episodes interbedded in the Bartonian (middle Eocene) of San Fausto–Lazkua area (Navarra region, North Spain), within a nearshore to inner‐ramp succession that, in spite of being deposited under general transgressive conditions, was highly influenced by terrigenous supply from the adjacent land. Up to twelve different seagrass bed intervals occur interbedded in a cyclical manner with high‐energy nearshore siliciclastics and inner ramp bioclastic carbonates rich in mesophotic−oligophotic foraminifers and heterozoan biota (red algae, echinoderms, bryozoans). Seagrass deposits exhibit typical unsorted textures, abundant bioturbation and moderate to high terrigenous content, and comprise a characteristic skeletal association of epiphytic foraminifers, red algae and, most particularly, of abundant encrusting acervulinids, commonly with distinct hooked and tubular growth forms. This abundance of suspension‐feeders relative to autotrophs and mixotrophs may be indicative of temperate waters, although the taxonomic diversity of the foraminiferal assemblages in both seagrass and non‐seagrass embedding deposits supports the interpretation of shallow, warm‐water conditions. The studied seagrass deposits provide evidence that high siliciclastic supply and associated nutrient input may determine the occurrence of temperate‐like seagrass deposits in warm‐water settings, analogous to extensive heterozoan carbonate production in modern shallow‐tropical environments. Thus, the identification and correct interpretation of past seagrass‐vegetated environments are crucial for reconstructing palaeoecological conditions in ancient shallow‐marine environments. Therefore, in comparison with carbonate‐dominated environments, the mixed terrigenous−carbonate seagrass deposits are volumetrically less important, presenting a more irregular, patchy distribution, and a skeletal assemblage dominated by heterotrophs, regardless of the water temperature.
LA PRESENTE TESIS SE HA CENTRADO EN EL ANALISIS ESTRATIGRAFICO, SEDIMENTOLOGICO Y PALEOGEOGRAFICO... more LA PRESENTE TESIS SE HA CENTRADO EN EL ANALISIS ESTRATIGRAFICO, SEDIMENTOLOGICO Y PALEOGEOGRAFICO DEL INTERVALO MAASTRICHTIENSE SUPERIOR-PALEOCENO- ILERDIENSE INFERIOR (MPI) DE LA REGION VASCO- CANTABRICA. DICHO ANALISIS SE HA REALIZADO BAJO UN ENFOQUE DE ESTRATIGRAFIA SECUENCIAL, HABIENDOSE RECONOCIDO UN TOTAL DE 8 SECUENCIAS DEPOSICIONALES DE VALOR REGIONAL (ASOCIABLES A CAMBIOS RELATIVOS DEL NIVEL DEL MAR DE TERCER ORDEN), CUYA EDAD SE HA CALIBRADO CON EXACTITUD MEDIANTE FORAMINIFEROS PLANCTONICOS, MACROFORAMINIFEROS Y MAGNETOESTRATIGRAFIA. A UNA ESCALA MAYOR, SE HA CONSTATADO QUE EL MPI FORMA PARTE DE UN CICLO TRANSGRESIVO-REGRESIVO DE SEGUNDO ORDEN, DESARROLLADO EN RESPUESTA A LA EVOLUCION TECTO-SEDIMENTARIA EXPERIMENTADA POR LA REGION. EL MPI CONSTITUYE, EN CONCRETO, EL HEMICICLO TRANSGRESIVO DE DICHA UNIDAD MAYOR. A SU VEZ, DENTRO DE EL, SE DEFINEN TRES FASES EVOLUTIVAS (T1, T2 Y T3), CARACTERIZADAS SOBRE TODO POR EL DESARROLLO DE UN DISPOSITIVO SEDIMENTARIO DIFERENCIADO Y POR EL MODO DE APILAMIENTO DE LAS SECUENCIAS. LAS 8 SECUENCIAS DEPOSICIONALES ESTAN PRINCIPALMENTE CONSTITUIDAS POR MATERIALES CARBONATADOS, PERO INCLUYEN TAMBIEN DEPOSITOS DE NATURALEZA SILICICLASTICA. EL ESTUDIO SEDIMENTOLOGICO DE TODOS ELLOS, COMBINADO CON LAS LABORES DE CARTOGRAFIA Y CORRELACION, HA PERMITIDO RECONOCER TODA UNA GAMA DE DOMINIOS DE SEDIMENTACION: UNA PLATAFORMA CARBONATADA SOMERA, DENTRO DE LA CUAL ESTAN REPRESENTADOS AMBIENTES Y SUBAMBIENTES DESDE CONTINENTALES Y/O TRANSICIONALES HASTA MARINO ABIERTOS; UNA ZONA DE TRANSICION PLATAFORMA-CUENCA, COMPUESTA A SU VEZ POR UN TALUD DE CARACTER FUNDAMENTALMENTE EROSIVO, Y UN PIE DE TALUD DEFINIDO POR ACUMULACIONES DE MATERIALES RESEDIMENTADOS DE PROCEDENCIA SOMERA; Y POR ULTIMO, UN AREA DE CUENCA PROFUNDA, DONDE ASIMISMO SE DEFINEN DOS SISTEMAS BIEN DIFERENCIADOS: UN FONDO DE CUENCA CARACTERIZADO POR SEDIMENTACION DE CARACTER PELAGICO Y/O HEMIPELAGICO, Y UN CANAL SUBMARINO PROFUNDO, RELLENA
The carbonate factories, their controlling factors and their palaeoecological and sedimentologica... more The carbonate factories, their controlling factors and their palaeoecological and sedimentological signals recorded in sedimentary successions are key elements for understanding the evolution of carbonate platform systems. Luis Pomar has dedicated most of his academic life to the study of carbonate rocks and carbonate factories. The idea for this special issue to celebrate Pomar’s career arose during a session at the 34th International Association of Sedimentologists meeting held in Rome, entitled ‘Understanding carbonate factories through palaeoecological and geochemical signals’. The proposal encountered great response among participants, and additional contributions followed an email invitation to other specialists. This issue contains a variety of papers on carbonate sedimentology and carbonate factories. Here, an introduction that contextualizes the papers and key concepts discussed in this thematic issue is provided. It reviews Luis Pomar’s major achievements in carbonate sedimentology and discusses the evolution of the concept of the carbonate factory and the series of palaeoecological and sedimentological signals used to characterize the wide spectrum of carbonate depositional systems found in the natural world.
In recent years, the discovery of isolated teeth from the Late Cretaceous (Campanian-Maastrichtia... more In recent years, the discovery of isolated teeth from the Late Cretaceous (Campanian-Maastrichtian) of the Basque-Cantabrian Region, in the north of the Iberian Peninsula, has permitted to recognise at least four different mosasaurid taxa in several sites of Alava and Condado de Treviño: Mosasaurus lemonnieri, Prognathodon solvayi, Platecarpus cf. ictericus and Tylosaurus sp. A new specimen, which consists of a fragment of skull with articulated portions of the maxilla and prefrontal, from the Campanian of Navarre is described here. This material is assigned to Prognathodon cf. sectorius on the basis of dental features. It constitutes the only cranial remain and the most significant mosasaurid fragment known to date in the Iberian Peninula. P. sectorius was previously recorded from the Maastrichtian of New-Jersey and The Netherlands.
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