The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Lindsay B. Collins - One of the best experts on this subject based on the ideXlab platform.
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Controls on microbial activity and tidal flat evolution in Shark Bay, Western Australia
Sedimentology, 2013Co-Authors: Ricardo Jahnert, Lindsay B. CollinsAbstract:Microbial deposits at Shark Bay constitute a diverse living microbial carbonate system, developed in a semi-arid, highly evaporative marine setting. Three tidal flats located in different embayments within the World Heritage area were investigated in order to compare microbial deposits and their Holocene evolution. The stressing conditions in the intertidal–Subtidal Environment have produced a microbial ecosystem that is trapping, binding and biologically inducing CaCO3 precipitation, producing laminated stromatolites (tufted, smooth and colloform), non-laminated thrombolitic forms (pustular) and cryptomicrobial non-laminated forms (microbial pavement). A general shallowing-upwards sedimentary cycle was recognized and correlated with Holocene sea-level variations, where microbial deposits constitute the younger (2360 years bp) and shallower sedimentary veneer. In addition, sediments have been documented with evidence of exposure during the Holocene, from 1040 to 940 14C years bp, when sea-level was apparently lower than present. Filamentous bacteria constitute the dominant group in the blister, tufted and smooth mat types, and coccus bacteria dominate the pustular, colloform and microbial pavement deposit types. In the Subtidal Environment within colloform and pavement structures, microbial communities coexist with organisms such as bivalves, serpulids, diatoms, green algae (Acetabularia), crustaceans, foraminifera and micro-gastropods, which are responsible for exoskeleton supply and extensive bioturbation. The internal fabric of the microbial deposits is laminated, sub-laminar, scalloped, irregular or clotted, depending on the amount of fine-grained carbonate and the natural ability of microbial communities to trap and bind particles or induce carbonate precipitation. Nilemah tidal flat contains the thickest (1·3 m) and best-developed microbial sedimentary system; its deposition pre-dated the Rocky Point and Garden Point tidal flats, with the most positive isotope values for δ13C and δ18O, reflecting strong microbial activity in a highly evaporative Environment. There is an evolutionary series preserved within the tidal flats reflecting relative ages and degree of salinity elevation.
Alan Moro - One of the best experts on this subject based on the ideXlab platform.
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Facies development and paleoecology of rudists and corals: an example of Campanian transgressive sediments from northern Croatia, northeastern Slovenia, and northwestern Bosnia
Facies, 2016Co-Authors: Alan Moro, Aleksander Horvat, Vladimir Tomić, Jasenka Sremac, Vladimir BermanecAbstract:At six localities in northern Croatia (Donje Orešje, Gornje Orešje), Slovenia (Stranice, Slovenj Gradec), and Bosnia (Bešpelj and Kober), successions of shallow-water Campanian deposits transgressively covered a tectonically uplifted and eroded paleorelief. They constitute different lateral parts of a transgressive Subtidal Environment, where rudists and corals are typical macrofossils. At the investigated localities, two types of succession were distinguished: (a) clastic and (b) carbonate. Most localities are within the extended chronostratigraphic range of Calveziconus cf. lecalvezae (80.5–79.03 Ma), which comprises the upper part of the Vaccinites alpinus interval zone (for Stranice and Slovenj Gradec localities) and beginning of the Pironaea polystyla interval zone (for Bešpelj and Kober localities). In clastic successions, corals are the most abundant macrofossils, whereas rudists predominate within carbonate sections. The depositional setting of the investigated localities results from rapid relative sea-level rise with a tectonic overprint, which covered different types of paleorelief. In cases when the paleorelief is gentle, a transgressive succession starts with clastic coral-rich sediments or carbonates with radiolitids. In areas of steeper paleorelief carbonate sediments were deposited with a mixed radiolitid-hippuritid community, and the rudists, as the major macrofossils, indicate higher sedimentation rates in comparison with the clastic situations.
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Rudists and dinosaur footprints : mutual relationship within mud-supported Upper Cenomanian peritidal limestones of Istria, Croatia
Bollettino Della Societa Geologica Italiana, 2008Co-Authors: Alan Moro, Aleksandar Mezga, Vlasta Ćosović, Giorgio Tunis, Alceo TarlaoAbstract:Upper Cenomanian peritidal limestones with dinosaur footprints are characterized by Subtidal wackestone-packstone bearing rudist congregations as well as intertidal laminites. In the shallow Subtidal Environment radiolitids, as mud-supported elevator dwellers, thrived almost exclusively in dense thickets or floatstones with toppled individuals, that pass vertically and laterally into peloidal-foraminiferal wackestone-packstone. As is the case for the rudists, dinosaur tracks are also preserved within peritidal Environments through the shallowing-upward cycles. However, unlike the rudists dinosaur tracks are present at the top of intertidal laminites. In cases when shallowing upward cycles ended with Subtidal limestones, the possibility of dinosaur footprint preservation on the emerged surfaces was prevented by karstification of the upper bedding plane. Appearance of radiolitids through biostromal congregations, as well as preservation of dinosaurs footprints on their upper bedding plane, imply absence of possible barriers made by radiolitids on the vast shallow-water Adriatic carbonate platform during Upper Cenomanian.
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Stratigraphy and paleoEnvironments of rudist biostromes in the Upper Cretaceous (Turonian-upper Santonian) limestones of southern Istria, Croatia.
Palaeogeography Palaeoclimatology Palaeoecology, 1997Co-Authors: Alan MoroAbstract:Abstract Rudists are well preserved in the Upper Cretaceous limestones of southern Istria, where they flourished within different shallow-water Environments during the Turonian to upper Santonian. In order to determine paleoEnvironments, a vertical succession of the rich rudist assemblages has been investigated and described within sequence stratigraphy framework. The Turonian to upper Santonian sediments of southern Istria, in the sense of sequence stratigraphy, comprise one complete third-order sequence and the beginning of the transgressive systems track (TST) of the next sequence. Lower Turonian pelagic limestones were deposited on a foundered carbonate platform, and represent the beginning of the TST. Limestones of the late TST-lowstand systems track (LST) were deposited on the inner shelf, and the early TST of the next sequence was deposited on the outer shelf. All the rudists which appeared after the early Turonian disappearance and partial extinction were elevators. The genera Durania and Praeradiolites thrived in bouquets, which may coalesce to form thickets in inner shelf Environments of the late TST-LST. Their growth depended completely ( Durania ) or partly ( Praeradiolites ) on net sediment accumulation. The Environment in which Durania and Praeradiolites thrived was Subtidal and deep enough to be out of reach of emersion. Within the same depositional Environment, these genera were later replaced vertically by Radiolites . Individuals with slim, cylindrical shells, and wide growth lamellae, have full contact within the thickets, in which their growth depended little, if at all, on net sedimentation rate. Also, Radiolites occupied the shallower parts of the Subtidal zone with a commissure rim rising above the sediment surface. Renewed deepening in the late Santonian resulted in the outer shelf Environment of the next TST. Gorjanovicia , together with rare Vaccinites , flourished after the Radiolites . Gorjanovicia differed from Radiolites only in possessing more pronounced vertical ribs. In their slightly deeper Subtidal Environment with pelagic influxes, Gorjanovicia thrived in bouquets. Loosely packed Gorjanovicia gave Vaccinites an opportunity to grow among them. The Environmental setting of the southern Istria rudist biostromes and their correlation with other shallow-water deposits in the Mediterranean region suggests that a sequence stratigraphy approach can be applied to correlate rudist biostratigraphy on a regional, or even inter-regional, scale.
Bernard Lathuiliere - One of the best experts on this subject based on the ideXlab platform.
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Microfacies, microtaphonomic traits and foraminiferal assemblages from Upper Jurassic oolitic–coral limestones: stratigraphic fluctuations in a shallowing-upward sequence (French Jura, Middle Oxfordian)
Facies, 2007Co-Authors: Matias Reolid, Christian Gaillard, Bernard LathuiliereAbstract:The characterization and distribution of the microfacies and the microfossil assemblages of a Middle Oxfordian section from Jura Mountains composed by thick oolitic–coral limestones is analyzed. Six microfacies types (mainly grainstones) are differentiated mainly composed by ooids, intraclasts and bioclasts. Foraminiferal assemblages are dominated by agglutinated forms. Benthic microbial communities and sessile foraminifera are the main components of the encrustations. The whole set of microfossil assemblages is typical of shallow Subtidal Environments rich in “algae” ( Cayeuxia , “ Solenopora ”, Thaumatoporella , Bacinella , Girvanella and Terquemella ) and foraminifera such as Nautiloculina oolithica , Redmondoides lugeoni , Ammobaculites coprolitiformis , Troglotella incrustans and Rectocyclammina . The increasing upward record of debris of algae and Nautiloculina , and the decrease of serpulids, bryozoans, nodosariids and ophthalmidiids indicate a shallowing-upward trend. The stratigraphic distribution of microfacies and microfossil assemblages lead to differentiate two main successive phases. The first is a deeper Subtidal Environment in an open shelf, while the second is a shallow Subtidal Environment with evolution from winnowed to more restricted conditions. Microfabrics of radial to concentric ooids upwards in the section correspond to higher energy Environments related to an oolitic shoal. This study shows how a very detailed analysis of microfacies, which integrates oolitic features, microfossil assemblages and microtaphonomy is potentially a useful tool for interpreting hydrodynamism and sequence evolution in marine carbonate shallow Environments.
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microfacies microtaphonomic traits and foraminiferal assemblages from upper jurassic oolitic coral limestones stratigraphic fluctuations in a shallowing upward sequence french jura middle oxfordian
Facies, 2007Co-Authors: Matias Reolid, Christian Gaillard, Bernard LathuiliereAbstract:The characterization and distribution of the microfacies and the microfossil assemblages of a Middle Oxfordian section from Jura Mountains composed by thick oolitic–coral limestones is analyzed. Six microfacies types (mainly grainstones) are differentiated mainly composed by ooids, intraclasts and bioclasts. Foraminiferal assemblages are dominated by agglutinated forms. Benthic microbial communities and sessile foraminifera are the main components of the encrustations. The whole set of microfossil assemblages is typical of shallow Subtidal Environments rich in “algae” (Cayeuxia, “Solenopora”, Thaumatoporella, Bacinella, Girvanella and Terquemella) and foraminifera such as Nautiloculina oolithica, Redmondoides lugeoni, Ammobaculites coprolitiformis, Troglotella incrustans and Rectocyclammina. The increasing upward record of debris of algae and Nautiloculina, and the decrease of serpulids, bryozoans, nodosariids and ophthalmidiids indicate a shallowing-upward trend. The stratigraphic distribution of microfacies and microfossil assemblages lead to differentiate two main successive phases. The first is a deeper Subtidal Environment in an open shelf, while the second is a shallow Subtidal Environment with evolution from winnowed to more restricted conditions. Microfabrics of radial to concentric ooids upwards in the section correspond to higher energy Environments related to an oolitic shoal. This study shows how a very detailed analysis of microfacies, which integrates oolitic features, microfossil assemblages and microtaphonomy is potentially a useful tool for interpreting hydrodynamism and sequence evolution in marine carbonate shallow Environments.
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Microfacies, microtaphonomic traits and foraminiferal assemblages from Upper Jurassic oolitic–coral limestones: stratigraphic Xuctuations in a shallowing-upward sequence (French Jura, Middle Oxfordian)
Facies, 2007Co-Authors: Matias Reolid, Christian Gaillard, Bernard LathuiliereAbstract:The characterization and distribution of the microfacies and the microfossil assemblages of a Middle Oxfordian section from Jura Mountains composed by thick oolitic–coral limestones is analyzed. Six microfacies types(mainly grainstones) are differentiated mainly composed by ooids, intraclasts and bioclasts. Foraminiferal assemblages are dominated by agglutinated forms. Benthic microbial communities and sessile foraminifera are the main components of the encrustations. The whole set of microfossil assemblages is typical of shallow Subtidal Environments rich in “algae” (Cayeuxia, “Solenopora”, Thaumatoporella, Bacinella, Girvanella and Terquemella) and foraminifera such as Nautiloculina oolithica, Redmondoides lugeoni, Ammobaculites coprolitiformis, Troglotella incrustans and Rectocyclammina. The increasing upward record of debris of algae and Nautiloculina, and the decrease of serpulids, bryozoans, nodosariids and ophthalmidiids indicate a shallowing- upward trend. The stratigraphic distribution of microfacies and microfossil assemblages lead to diVerentiate two main successive phases. The Wrst is a deeper Subtidal Environment in an open shelf, while the second is a shallow Subtidal Environment with evolution from winnowed to more restricted conditions. Microfabrics of radial to concentric ooids upwards in the section correspond to higher energy Environments related to an oolitic shoal. This study shows how a very detailed analysis of microfacies, which integrates oolitic features, microfossil assemblages and microtaphonomy is potentially a useful tool for interpreting hydrodynamism and sequence evolution in marine carbonate shallow Environments.
Ricardo Jahnert - One of the best experts on this subject based on the ideXlab platform.
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Controls on microbial activity and tidal flat evolution in Shark Bay, Western Australia
Sedimentology, 2013Co-Authors: Ricardo Jahnert, Lindsay B. CollinsAbstract:Microbial deposits at Shark Bay constitute a diverse living microbial carbonate system, developed in a semi-arid, highly evaporative marine setting. Three tidal flats located in different embayments within the World Heritage area were investigated in order to compare microbial deposits and their Holocene evolution. The stressing conditions in the intertidal–Subtidal Environment have produced a microbial ecosystem that is trapping, binding and biologically inducing CaCO3 precipitation, producing laminated stromatolites (tufted, smooth and colloform), non-laminated thrombolitic forms (pustular) and cryptomicrobial non-laminated forms (microbial pavement). A general shallowing-upwards sedimentary cycle was recognized and correlated with Holocene sea-level variations, where microbial deposits constitute the younger (2360 years bp) and shallower sedimentary veneer. In addition, sediments have been documented with evidence of exposure during the Holocene, from 1040 to 940 14C years bp, when sea-level was apparently lower than present. Filamentous bacteria constitute the dominant group in the blister, tufted and smooth mat types, and coccus bacteria dominate the pustular, colloform and microbial pavement deposit types. In the Subtidal Environment within colloform and pavement structures, microbial communities coexist with organisms such as bivalves, serpulids, diatoms, green algae (Acetabularia), crustaceans, foraminifera and micro-gastropods, which are responsible for exoskeleton supply and extensive bioturbation. The internal fabric of the microbial deposits is laminated, sub-laminar, scalloped, irregular or clotted, depending on the amount of fine-grained carbonate and the natural ability of microbial communities to trap and bind particles or induce carbonate precipitation. Nilemah tidal flat contains the thickest (1·3 m) and best-developed microbial sedimentary system; its deposition pre-dated the Rocky Point and Garden Point tidal flats, with the most positive isotope values for δ13C and δ18O, reflecting strong microbial activity in a highly evaporative Environment. There is an evolutionary series preserved within the tidal flats reflecting relative ages and degree of salinity elevation.
Susan S Bell - One of the best experts on this subject based on the ideXlab platform.
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seagrass landscapes a terrestrial approach to the marine Subtidal Environment
Trends in Ecology and Evolution, 1994Co-Authors: Bradley D Robbins, Susan S BellAbstract:Abstract Subtidal seagrass habitats are prime candidates for the application of principles derived from landscape ecology. Although seagrass systems are relatively simple compared to their terrestrial counterparts in terms of species diversity and structural complexity, seagrasses do display variation in spatial patterns over a variety of scales. The presence of a moving water layer and its influence on faunal dispersal may be a distinguishing feature impacting ecological processes in the Subtidal zone. Studying seagrass-dominated landscapes may provide a novel approach to investigating questions regarding self-similarity of spatial patterns, and offers a new perspective for analysing habitat change in a variety of marine Environments.
