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  • Oncoid distribution in the shallow domains of a Kimmeridgian Carbonate Ramp (Late Jurassic, NE Spain)
    Sedimentary Geology, 2020
    Co-Authors: Cristina Sequero, Marcos Aurell, Beatriz Badenas
    Abstract:

    Abstract The distribution and abundance of oncoids in the shallow domains of a latest Kimmeridgian Carbonate Ramp was accomplished on the basis of a detailed sedimentological and petrographic analysis of the lower part of the Higueruelas Formation (Iberian Basin, northeastern Spain). Six types of oncoids are recognized based on the internal structure of the cortex, and show a preferential distribution on the Carbonate Ramp, which record from intertidal, lagoon, backshoal, shoal-sand blanket, foreshoal to offshore domains. Spherical type I oncoids, composed of continuous micritic laminae, occur in all the subenvironments in low proportions. Sub-spherical type II oncoids, constituted by micritic laminae and discontinuous organism-bearing laminae of mostly Bacinella irregularis, dominate in the higher-energy shoal-sand blanket domain. Type III oncoids, with alternating micritic and organism-bearing laminae of mostly Bacinella irregularis-Lithocodium aggregatum association, include two varieties: type IIIa oncoids, with micritic and organism-bearing laminae of similar thickness, preferentially formed in the foreshoal domain; and type IIIb oncoids, with thinner micritic laminae, formed in a low-energy sheltered lagoon. Irregular type IV oncoids characterize the low-energy settings, and include two varieties: type IVa oncoids, mainly consisting of a Bacinella-Lithocodium meshwork, which occur abundantly in the lagoon; and less abundant type IVb oncoids, composed of a continuous organism-bearing laminae of Lithocodium, which are found in the offshore domain. Water energy and platform morphology played an important role in formation and distribution of the oncoids in these shallow domains, where normal-marine water and oligotrophic conditions are highlighted by the high-diversity of light-dependant micro-encrusters in type III and IV oncoids. Comparable oncoid distribution patterns of diverse Late Jurassic shallow Carbonate platforms enhance their potential use as reliable palaeoenvironmental proxies.

  • Factors Controlling Oncoid Distribution in the Inner Areas of a Late Kimmeridgian Carbonate Ramp (Northeast Spain)
    Paleobiodiversity and Tectono-Sedimentary Records in the Mediterranean Tethys and Related Eastern Areas, 2019
    Co-Authors: Cristina Sequero, Beatriz Badenas, Marcos Aurell
    Abstract:

    The factors controlling the oncoid distribution in the interior areas of a latest Kimmeridgian shallow Carbonate Ramp were examined based on a detailed sedimentological and petrographic analysis of the upper sequence of the Higueruelas Formation (Iberian Basin, Northeast Spain). Four types of oncoids are defined: small micrite-dominated type I and II oncoids are generally found in low proportion in all sub-environments (from backshoal/washover, lagoon to intertidal). Large Bacinella-dominated type III and IV oncoids predominate in low-energy lagoonal areas. Variable energy water, oligotrophic conditions and probably low sedimentation rates controlled oncoid growth and distribution, thus highlighting their potential as palaeo-environmental proxies.

  • Sedimentary evolution of a shallow Carbonate Ramp (Kimmeridgian, NE Spain): Unravelling controlling factors for facies heterogeneities at reservoir scale
    Marine and Petroleum Geology, 2019
    Co-Authors: Cristina Sequero, Marcos Aurell, Beatriz Badenas
    Abstract:

    Abstract The facies evolution of a Late Jurassic (latest Kimmeridgian) shallow Carbonate Ramp was reconstructed after the analysis and correlation of 21 logs in a 20 × 30 km outcrop area located south of Zaragoza (northeast Spain). The studied succession belongs to the Higueruelas Formation, which is of potential use as an analogue for understanding facies heterogeneities in certain hydrocarbon Carbonate reservoirs (e.g. the Arab Formation, Persian Gulf). The studied succession is arranged in nine sedimentary units bounded by discontinuity surfaces that can be traced over kilometres. Facies analysis permitted the reconstruction of two sedimentary models showing the transition from inner Ramp subenvironments (i.e. intertidal, lagoon, backshoal/washover, shoal-sand blanket) to the mid-Ramp foreshoal and offshore domains: an oncolitic-peloidal-oolitic and an oolitic-peloidal-dominated Ramp. The oncolitic-peloidal-oolitic-dominated Ramp is characterized by peloidal-oolitic and oncolitic-dominated shoal-sand blankets that developed in higher-energy inner areas, protecting peloidal-oolitic backshoal and oncolitic lagoon domains including a mosaic of stromatoporoid carpets. Peloidal facies with fenestral porosity accumulated in an intertidal belt or as patches on top of the shoal-sand blankets and washover deposits. Offshore from the shoal-sand blankets, chaetetid/stromatoporoid/coral-rich buildups grew on the more proximal mid-Ramp, surrounded by peloidal and peloidal-bioclastic grain- to mud-supported facies. An oolitic-peloidal-dominated Ramp developed in a second stage of the evolution of the platform, characterized by the presence of a wide restricted peloidal-bioclastic-oolitic lagoon on the inner Ramp grading into a backshoal area dominated by storm-related intraclastic-peloidal deposits. Stromatoporoid carpets disappeared and oncolitic-dominated deposits were constrained to the foreshoal and backshoal domains, and locally to local ponds that developed in the intertidal belt or the restricted lagoon. Internal and external factors controlling facies heterogeneity and the sedimentary evolution of the Carbonate Ramp include resedimentation, topographic relief, and long- to short-term sea-level fluctuations.

  • Facies mosaic in the inner areas of a shallow Carbonate Ramp (Upper Jurassic, Higueruelas Fm, NE Spain)
    Facies, 2018
    Co-Authors: Cristina Sequero, Beatriz Badenas, Marcos Aurell
    Abstract:

    The internal facies and sedimentary architecture of an Upper Jurassic inner Carbonate Ramp were reconstructed after the analysis and correlation of 14 logs in a 1 × 2 km outcrop area around the Mezalocha locality (south of Zaragoza, NE Spain). The studied interval is 10–16 m thick and belongs to the upper part of the uppermost Kimmeridgian–lower Tithonian Higueruelas Fm. On the basis of texture and relative proportion of the main skeletal and non-skeletal components, 6 facies and 12 subfacies were differentiated, which record subtidal (backshoal/washover, sheltered lagoon and pond/restricted lagoon) to intertidal subenvironments. The backshoal/washover subenvironment is characterized by peloidal wackestone–packstone and grainstone. The lagoon subenvironment includes oncolitic, stromatoporoid, and oncolitic-stromatoporoid (wackestone and packstone) facies. The intertidal subenvironment is represented by peloidal mudstone and packstone–grainstone with fenestral porosity. Gastropod-oncolitic (wackestone–packstone and grainstone) facies with intercalated marl may reflect local ponds in the intertidal or restricted lagoon subenvironments. Detailed facies mapping allowed us to document 7 sedimentary units within a general shallowing-upward trend, which reflect a mosaic distribution, especially for stromatoporoid and fenestral facies, with facies patches locally more than 500 m in lateral extent. External and internal factors controlled this heterogeneity, including resedimentation, topographic relief and substrate stability, combined with variations in sea-level. This mosaic facies distribution provides useful tools for more precise reconstructions of depositional heterogeneities, and this variability must be taken into account in order to obtain a solid sedimentary framework at the kilometer scale.

  • cyclostratigraphy and chemostratigraphy of a bioclastic storm dominated Carbonate Ramp late pliensbachian iberian basin
    Sedimentary Geology, 2017
    Co-Authors: Beatriz Badenas, Marcos Aurell, Idoia Rosales
    Abstract:

    Abstract Deposition of regressive successions and coeval positive trend in the oxygen stable isotope record in relatively deep marine successions of the upper Pliensbachian of western European basins have been related to a cooling interlude within the warm greenhouse conditions of the Pliensbachian. Sedimentological, cyclostratigraphic and chemostratigraphic analyses carried out in two upper Pliensbachian successions exposed in the Iberian Chain (Obon and San Pedro localities, Spain) allowed the characterization of the imprint of this cooling interlude on the relatively shallow areas of the Iberian Carbonate Ramp. The upper Pliensbachian succession is characterized by skeletal limestones and encompasses proximal mid-Ramp to proximal outer-Ramp facies, in which resedimentation and reworking by storm-induced flows controlled the accumulation of bioclastic debris. Two orders of high-frequency, metre-scale sequences have been identified: bundles of beds, and deepening-shallowing sets of bundles. According to the age calibration (previous biostratigraphic data and new strontium isotopes data) and correlation with nearby sections, these sequences are suggested as formed in tune with the short-term and long-term eccentricity Milankovitch cycles. The isotopic data from brachiopod shells and belemnite rostra indicate progressively increasing δ18O and slightly decreasing δ13C trends for the uppermost Pliensbachian Spinatum Zone, reflecting the influence of cooling conditions. However, facies analysis reflects that the expected coeval long-term regression was interrupted by a tectonically driven transgressive event in the uppermost part of the Spinatum Zone.

Marc Aurell - One of the best experts on this subject based on the ideXlab platform.

  • Carbonate Ramp drowning caused by flexural subsidence: The South Pyrenean middle Eocene foreland basin
    Sedimentary Geology, 2019
    Co-Authors: R. Silva-casal, Aitor Payros, Emilio L. Pueyo, Marc Aurell, Josep Serra-kiel
    Abstract:

    Abstract A detailed sedimentological and magnetostratigraphic analysis of three selected sections of the Eocene Carbonate platforms of the South Pyrenean Jaca-Pamplona foreland basin has been carried out in the Aragonese External Sierras (Huesca, Spain). The stratigraphic record spans from the middle-late Lutetian (Chron 20r, SBZ15) to the Bartonian (Chron 18r, SBZ17). The Lutetian-Bartonian transition was characterized by a major paleogeographic change, from a turbiditic foredeep with associated peripheral Carbonate Ramps to deltaic sedimentation. In most of the outcrops of the External Sierras, the peripheral Carbonate platforms (Guara Formation) are overlained by prodelta and outer Ramp marls (Arguis Formation). The drowning unconformity between these two formations in the outcrops located in the westernmost tip of the External Sierras is documented herein for the first time. In this area, the Guara Formation is overlain by glauconitic limestones deposited in a Carbonate Ramp setting. Between these units a characteristic unconformity is observed, with hard-ground formation and local evidence of subaerial exposure in the shallowest domains of the study area. The abundant glauconite found on top of this unconformity records a starvation period in the basin, followed by the development of a new Carbonate Ramp system during Bartonian times (Santo Domingo Member of the Arguis Formation). Magnetostratigraphic and sedimentological data show that tectonic tilting occurred in latest Lutetian times, prior to the drowning process. This suggests the influence of the flexural subsidence in the cratonic margin of the foreland as a result of the advance of a basement thrust in the hinterland. Nevertheless, the correlation of the uppermost Lutetian drowning unconformity with a basinwide regional sea level rise, which may have further been global, suggests an interplay between tectonic and eustatic processes in the drowning of the late Lutetian South Pyrenean Carbonate Ramps. In this work we point out a narrowing of the Carbonate Ramp, together with a relative sea level rise, as the processes responsible for the drowning of the Upper Guara Mb Carbonate Ramp. These processes could be responsible for the development of drowning unconformities in cratonic margins of other foreland basins. As Carbonate Ramps have a high sediment production potential, the narrowing of the Carbonate factory could provide the conditions for the drowning of the Carbonate Ramp system in a subsequent sea level rise.

  • Variations in petrophysical properties along a mixed siliciclastic Carbonate Ramp (Upper Jurassic, Ricla, NE Spain)
    Marine and Petroleum Geology, 2015
    Co-Authors: L.m. Kleipool, Beatriz Badenas, John J. G. Reijmer, Marc Aurell
    Abstract:

    Abstract A multi-scale petrophysical study was performed on an Upper Jurassic siliciclastic – Carbonate Ramp system near the village of Ricla (Spain). A combination of textural (field observations, thin section and grain-size analysis), chemical – mineralogical (thermo gravimetric analysis) and physical (porosity, gamma ray and velocity measurements) properties was used to capture the heterogeneity of this mixed sedimentary system. Subsequently, synthetic seismic sections with varying resolution were created to show the characteristics of the internal Ramp-structures. The translation from the measured petrophysical properties to a synthetic seismic section helps to better understand subsurface seismic. Although upscaling problems are a recurring issue, the homogeneity of the samples and the continuity of the outcrop and facies reduce the number of uncertainties. Acoustic properties are generally controlled by the amount and type of pore spaces. Due to the low porosities (ϕ  The Ramp geometry is characterized by an overall lateral homogeneity and vertical heterogeneity. Textural, sedimentological and stratigraphic transitions in the outcrop are related to the defined facies, each has its own unique mineralogical signature. Amplitude variations in the synthetic seismic profile are primarily caused by changes in mineral composition thus facies transitions.

  • Facies heterogeneity of a Kimmeridgian Carbonate Ramp (Jabaloyas, eastern Spain): a combined outcrop and 3D geomodelling analysis.
    Journal of Iberian Geology, 2014
    Co-Authors: G. San Miguel, Beatriz Badenas, Marc Aurell, Víctor Martínez, B. Caline, Cecile Pabian-goyheneche, J.p. Rolando, N. Grasseau
    Abstract:

    The Upper Kimmeridgian outcrops exposed around the village of Jabaloyas (NE Spain) have been analyzed to document the facies heterogeneity across the shallow portion of a low angle Carbonate Ramp. The studied area covers a total surface of 12 square kilometres. Seventeen stratigraphic profiles have provided basic information to carry out the detailed facies analyses presented in this work. The studied unit corresponds to a high-frequency sequence, bounded by discontinuities that can be traced at regional scale. This sequence shows the widespread development of coral-microbial reef buildups with conical to cylindrical shape (up to 19 m thick). The characterization and interpretation of the different sort of inter-reef and post-reef facies resulted in the reconstruction of the sedimentary domains of the studied Carbonate Ramp, from burrowed mud-dominated skeletal facies (distal middle Ramp), to grainy (skeletal, peloidal, oolitic) shoal and backshoal facies (inner Ramp). The studied sequence is divided into four sedimentary episodes bounded by sharp facies changes. The lower two episodes include the vertical reef growth during rapid accommodation gain; the upper two episodes are marked by the rapid progradation of the inner Ramp facies. The depositional facies and their stacking patterns in the Jabaloyas outcrops are similar to those described in the subsurface Arab D reservoirs. This Late Jurassic Carbonate unit forms major hydrocarbon fields in the Middle East. For improving the geological distribution of reservoir heterogeneity in this kind of low angle Carbonate Ramp system, two 3D models have been created. A Fullfield Model of the overall geometry of the facies belts has allowed the quantification of vertical and lateral extension of the inter-reef and post-reef facies. A Sector Model, which includes individual reef bodies has been used to better simulate reservoir heterogeneity resulting from different diagenetic overprint.

  • A facies model for internalites (internal wave deposits) on a gently sloping Carbonate Ramp (Upper Jurassic, Ricla, NE Spain)
    Sedimentary Geology, 2012
    Co-Authors: Beatriz Badenas, Marc Aurell, Luis Pomar, Michele Morsilli
    Abstract:

    Abstract Internal waves are waves that propagate along the pycnocline, the interface between two density-stratified fluids. Even though internal waves are ubiquitous in oceans and lakes, their impact in the sedimentary record has remained largely unrecognized. Internal waves can remobilize the sediment from the depth at which the internal waves break onto the sea floor. In shelf, or Ramp settings, internal wave deposits (internalites) have to be distinguished from tempestites while in slope and deeper settings internalites require distinction from turbidites. The Upper Kimmeridgian Carbonate Ramp succession cropping out near Ricla (NE Spain) provides some key evidence to differentiate the depositional processes induced by breaking internal waves from those related to surface storm waves. Sandy-oolitic grainstone eventites, previously interpreted as tempestites, contain evidence of reworking by turbulent events related to breaking internal waves. Underlying rationale are: 1) they occur in distal mid-Ramp position, detached from the coeval shallow-water successions; 2) they do not have the characteristic coarsening- and thickening upward trend of storm deposits; 3) they gradually thin-out to disappear both up dip and down dip, interbedded with mid-Ramp lime mudstones; and 4) they show little or no erosion towards the shallower areas. A facies model for internalites produced by two sediment populations, sand and mud, on a gently sloping Carbonate Ramp is proposed. The individual internalites occurring at Ricla include several architectural elements, sequentially organized in dip direction, which can be related to the flows associated with breaking internal waves: erosion in the breaker zone, swash run-up and tractive backwash flow. Individual internalites stack, with down- and up-slope shingling configuration, in dm-thick packages thought to reflect the up-slope and down-slope migration of the breaker zone, in turn related to depth variations of the palaeo-pycnocline. Packages occur in dm- to m-thick clusters suggested to reflect changes in sediment supply and/or variations in water stratification affecting the energy of internal waves.

  • continuity and facies heterogeneities of shallow Carbonate Ramp cycles sinemurian lower jurassic north east spain
    Sedimentology, 2010
    Co-Authors: Beatriz Badenas, Marc Aurell, Dan Bosence
    Abstract:

    The lateral continuity and facies heterogeneities of metre-scale cycles in a greenhouse Lower Jurassic (Sinemurian) Carbonate Ramp from the northern Iberian Basin (Spain) was evaluated from extensive field analysis carried out on a well-exposed 12 km long outcrop. Eleven high-frequency continuous cycles and their bounding surfaces are traceable laterally through the entire outcrop. However, three of these cycles are found to split laterally into discontinuous cycles of more limited distribution (up to 3 to 5 km of lateral extent). The continuous and discontinuous cycles have a similar field expression in one-dimensional logs. As a consequence, the number of cycles that can be differentiated is variable along the logged sections (i.e. from 11 to 16). Cycles have variable facies heterogeneities and sedimentary trends depending on the environment of formation: shallowing-upward and symmetrical cycles occur in protected lagoon–tidal flat areas and in the open-marine, high-energy domain. These cycles show significant facies heterogeneities, which were controlled mainly by lateral migration of a mosaic of facies over an irregular topography. Deepening-upward and aggradational cycles are generated in low-energy, sub wave-base, open-marine areas. Facies are laterally homogeneous, reflecting low potential for Carbonate accumulation and inability to fill the created accommodation space in this low-relief and relatively deep area. Cycle boundaries are generated by stages of rapid accommodation gain, involving the flooding of the Carbonate Ramp; they are more likely to originate from regional tectonic pulses (related to the extensional tectonics operating in the northern Iberian Basin) rather than greenhouse low-amplitude eustacy. Discontinuous cycles tend to occur in thickened areas and are interpreted as originating from the infill of wedge-shaped accommodation space resulting from differential subsidence (i.e. local tectonic pulses). In conclusion, where thickness variations occur in extensional settings lateral continuity of cycles should not be expected. In less well-exposed, or in one-dimensional sections and in wells, it would not be possible to distinguish continuous from discontinuous cycles, or to understand such two-dimensional heterogeneities. Identification of unique cycle-forming mechanisms or attempting cyclostratigraphic long-distance correlation of cycles is unrealistic without a detailed analysis of the architecture of cycles in laterally continuous outcrops.

Marcos Aurell - One of the best experts on this subject based on the ideXlab platform.

  • Oncoid distribution in the shallow domains of a Kimmeridgian Carbonate Ramp (Late Jurassic, NE Spain)
    Sedimentary Geology, 2020
    Co-Authors: Cristina Sequero, Marcos Aurell, Beatriz Badenas
    Abstract:

    Abstract The distribution and abundance of oncoids in the shallow domains of a latest Kimmeridgian Carbonate Ramp was accomplished on the basis of a detailed sedimentological and petrographic analysis of the lower part of the Higueruelas Formation (Iberian Basin, northeastern Spain). Six types of oncoids are recognized based on the internal structure of the cortex, and show a preferential distribution on the Carbonate Ramp, which record from intertidal, lagoon, backshoal, shoal-sand blanket, foreshoal to offshore domains. Spherical type I oncoids, composed of continuous micritic laminae, occur in all the subenvironments in low proportions. Sub-spherical type II oncoids, constituted by micritic laminae and discontinuous organism-bearing laminae of mostly Bacinella irregularis, dominate in the higher-energy shoal-sand blanket domain. Type III oncoids, with alternating micritic and organism-bearing laminae of mostly Bacinella irregularis-Lithocodium aggregatum association, include two varieties: type IIIa oncoids, with micritic and organism-bearing laminae of similar thickness, preferentially formed in the foreshoal domain; and type IIIb oncoids, with thinner micritic laminae, formed in a low-energy sheltered lagoon. Irregular type IV oncoids characterize the low-energy settings, and include two varieties: type IVa oncoids, mainly consisting of a Bacinella-Lithocodium meshwork, which occur abundantly in the lagoon; and less abundant type IVb oncoids, composed of a continuous organism-bearing laminae of Lithocodium, which are found in the offshore domain. Water energy and platform morphology played an important role in formation and distribution of the oncoids in these shallow domains, where normal-marine water and oligotrophic conditions are highlighted by the high-diversity of light-dependant micro-encrusters in type III and IV oncoids. Comparable oncoid distribution patterns of diverse Late Jurassic shallow Carbonate platforms enhance their potential use as reliable palaeoenvironmental proxies.

  • Factors Controlling Oncoid Distribution in the Inner Areas of a Late Kimmeridgian Carbonate Ramp (Northeast Spain)
    Paleobiodiversity and Tectono-Sedimentary Records in the Mediterranean Tethys and Related Eastern Areas, 2019
    Co-Authors: Cristina Sequero, Beatriz Badenas, Marcos Aurell
    Abstract:

    The factors controlling the oncoid distribution in the interior areas of a latest Kimmeridgian shallow Carbonate Ramp were examined based on a detailed sedimentological and petrographic analysis of the upper sequence of the Higueruelas Formation (Iberian Basin, Northeast Spain). Four types of oncoids are defined: small micrite-dominated type I and II oncoids are generally found in low proportion in all sub-environments (from backshoal/washover, lagoon to intertidal). Large Bacinella-dominated type III and IV oncoids predominate in low-energy lagoonal areas. Variable energy water, oligotrophic conditions and probably low sedimentation rates controlled oncoid growth and distribution, thus highlighting their potential as palaeo-environmental proxies.

  • Sedimentary evolution of a shallow Carbonate Ramp (Kimmeridgian, NE Spain): Unravelling controlling factors for facies heterogeneities at reservoir scale
    Marine and Petroleum Geology, 2019
    Co-Authors: Cristina Sequero, Marcos Aurell, Beatriz Badenas
    Abstract:

    Abstract The facies evolution of a Late Jurassic (latest Kimmeridgian) shallow Carbonate Ramp was reconstructed after the analysis and correlation of 21 logs in a 20 × 30 km outcrop area located south of Zaragoza (northeast Spain). The studied succession belongs to the Higueruelas Formation, which is of potential use as an analogue for understanding facies heterogeneities in certain hydrocarbon Carbonate reservoirs (e.g. the Arab Formation, Persian Gulf). The studied succession is arranged in nine sedimentary units bounded by discontinuity surfaces that can be traced over kilometres. Facies analysis permitted the reconstruction of two sedimentary models showing the transition from inner Ramp subenvironments (i.e. intertidal, lagoon, backshoal/washover, shoal-sand blanket) to the mid-Ramp foreshoal and offshore domains: an oncolitic-peloidal-oolitic and an oolitic-peloidal-dominated Ramp. The oncolitic-peloidal-oolitic-dominated Ramp is characterized by peloidal-oolitic and oncolitic-dominated shoal-sand blankets that developed in higher-energy inner areas, protecting peloidal-oolitic backshoal and oncolitic lagoon domains including a mosaic of stromatoporoid carpets. Peloidal facies with fenestral porosity accumulated in an intertidal belt or as patches on top of the shoal-sand blankets and washover deposits. Offshore from the shoal-sand blankets, chaetetid/stromatoporoid/coral-rich buildups grew on the more proximal mid-Ramp, surrounded by peloidal and peloidal-bioclastic grain- to mud-supported facies. An oolitic-peloidal-dominated Ramp developed in a second stage of the evolution of the platform, characterized by the presence of a wide restricted peloidal-bioclastic-oolitic lagoon on the inner Ramp grading into a backshoal area dominated by storm-related intraclastic-peloidal deposits. Stromatoporoid carpets disappeared and oncolitic-dominated deposits were constrained to the foreshoal and backshoal domains, and locally to local ponds that developed in the intertidal belt or the restricted lagoon. Internal and external factors controlling facies heterogeneity and the sedimentary evolution of the Carbonate Ramp include resedimentation, topographic relief, and long- to short-term sea-level fluctuations.

  • Facies mosaic in the inner areas of a shallow Carbonate Ramp (Upper Jurassic, Higueruelas Fm, NE Spain)
    Facies, 2018
    Co-Authors: Cristina Sequero, Beatriz Badenas, Marcos Aurell
    Abstract:

    The internal facies and sedimentary architecture of an Upper Jurassic inner Carbonate Ramp were reconstructed after the analysis and correlation of 14 logs in a 1 × 2 km outcrop area around the Mezalocha locality (south of Zaragoza, NE Spain). The studied interval is 10–16 m thick and belongs to the upper part of the uppermost Kimmeridgian–lower Tithonian Higueruelas Fm. On the basis of texture and relative proportion of the main skeletal and non-skeletal components, 6 facies and 12 subfacies were differentiated, which record subtidal (backshoal/washover, sheltered lagoon and pond/restricted lagoon) to intertidal subenvironments. The backshoal/washover subenvironment is characterized by peloidal wackestone–packstone and grainstone. The lagoon subenvironment includes oncolitic, stromatoporoid, and oncolitic-stromatoporoid (wackestone and packstone) facies. The intertidal subenvironment is represented by peloidal mudstone and packstone–grainstone with fenestral porosity. Gastropod-oncolitic (wackestone–packstone and grainstone) facies with intercalated marl may reflect local ponds in the intertidal or restricted lagoon subenvironments. Detailed facies mapping allowed us to document 7 sedimentary units within a general shallowing-upward trend, which reflect a mosaic distribution, especially for stromatoporoid and fenestral facies, with facies patches locally more than 500 m in lateral extent. External and internal factors controlled this heterogeneity, including resedimentation, topographic relief and substrate stability, combined with variations in sea-level. This mosaic facies distribution provides useful tools for more precise reconstructions of depositional heterogeneities, and this variability must be taken into account in order to obtain a solid sedimentary framework at the kilometer scale.

  • cyclostratigraphy and chemostratigraphy of a bioclastic storm dominated Carbonate Ramp late pliensbachian iberian basin
    Sedimentary Geology, 2017
    Co-Authors: Beatriz Badenas, Marcos Aurell, Idoia Rosales
    Abstract:

    Abstract Deposition of regressive successions and coeval positive trend in the oxygen stable isotope record in relatively deep marine successions of the upper Pliensbachian of western European basins have been related to a cooling interlude within the warm greenhouse conditions of the Pliensbachian. Sedimentological, cyclostratigraphic and chemostratigraphic analyses carried out in two upper Pliensbachian successions exposed in the Iberian Chain (Obon and San Pedro localities, Spain) allowed the characterization of the imprint of this cooling interlude on the relatively shallow areas of the Iberian Carbonate Ramp. The upper Pliensbachian succession is characterized by skeletal limestones and encompasses proximal mid-Ramp to proximal outer-Ramp facies, in which resedimentation and reworking by storm-induced flows controlled the accumulation of bioclastic debris. Two orders of high-frequency, metre-scale sequences have been identified: bundles of beds, and deepening-shallowing sets of bundles. According to the age calibration (previous biostratigraphic data and new strontium isotopes data) and correlation with nearby sections, these sequences are suggested as formed in tune with the short-term and long-term eccentricity Milankovitch cycles. The isotopic data from brachiopod shells and belemnite rostra indicate progressively increasing δ18O and slightly decreasing δ13C trends for the uppermost Pliensbachian Spinatum Zone, reflecting the influence of cooling conditions. However, facies analysis reflects that the expected coeval long-term regression was interrupted by a tectonically driven transgressive event in the uppermost part of the Spinatum Zone.

Maria Paula Iglesia Llanos - One of the best experts on this subject based on the ideXlab platform.

  • cyclostratigraphy of an orbitally driven tithonian valanginian Carbonate Ramp succession southern mendoza argentina implications for the jurassic cretaceous boundary in the neuquen basin
    Sedimentary Geology, 2015
    Co-Authors: Diego Alejandro Kietzmann, Ricardo M Palma, Maria Paula Iglesia Llanos
    Abstract:

    We conducted detailed sedimentological, sequence-stratigraphic, and cyclostratigraphic analyses on four sections of the Vaca Muerta Formation. This unit is characterized by a decimetre-scale rhythmic alternation of marls and limestones. It consists of five facies associations, which represent basin to middle Carbonate Ramp deposits. The rhythmic vertical organization shows a well-ordered hierarchy of cycles, where elementary cycles, bundles of cycles, and superbundles within the Milankovitch frequency band are recognized. Cyclostratigraphic data allowed us to build a floating orbital scale for the lower Tithonian–lower Valanginian interval in the Neuquen Basin. Orbital calibration of these sections is consistent with Riccardi’s biostratigraphic scheme, which places the Jurassic–Cretaceous boundary within the Substeueroceras koeneni ammonite Zone (equivalent to Durangites spp., Jacobi/Grandis, and initial Occitanica standard zones).

  • Cyclostratigraphy of an orbitally-driven Tithonian–Valanginian Carbonate Ramp succession, Southern Mendoza, Argentina: Implications for the Jurassic–Cretaceous boundary in the Neuquén Basin
    Sedimentary Geology, 2015
    Co-Authors: Diego Alejandro Kietzmann, Ricardo M Palma, Maria Paula Iglesia Llanos
    Abstract:

    We conducted detailed sedimentological, sequence-stratigraphic, and cyclostratigraphic analyses on four sections of the Vaca Muerta Formation. This unit is characterized by a decimetre-scale rhythmic alternation of marls and limestones. It consists of five facies associations, which represent basin to middle Carbonate Ramp deposits. The rhythmic vertical organization shows a well-ordered hierarchy of cycles, where elementary cycles, bundles of cycles, and superbundles within the Milankovitch frequency band are recognized. Cyclostratigraphic data allowed us to build a floating orbital scale for the lower Tithonian–lower Valanginian interval in the Neuquen Basin. Orbital calibration of these sections is consistent with Riccardi’s biostratigraphic scheme, which places the Jurassic–Cretaceous boundary within the Substeueroceras koeneni ammonite Zone (equivalent to Durangites spp., Jacobi/Grandis, and initial Occitanica standard zones).

John P Grotzinger - One of the best experts on this subject based on the ideXlab platform.

  • Facies, stratigraphy, and evolution of a middle Ediacaran Carbonate Ramp: Khufai Formation, Sultanate of Oman
    AAPG Bulletin, 2014
    Co-Authors: Magdalena R. Osburn, John P Grotzinger, Kristin D. Bergmann
    Abstract:

    The Khufai Formation is the oldest Carbonate platform of the Cryogenian to lowermost Cambrian Huqf Supergroup. A stratigraphic characterization of this unit includes detailed facies descriptions, a sequence-stratigraphic interpretation, and evaluation of lateral heterogeneity and overall Ramp evolution. The Khufai Formation comprises one and one-half depositional sequences with a maximum flooding interval near the base of the formation and a sequence boundary within the upper peritidal facies. Most of the deposition occurred during highstand progradation of a Carbonate Ramp. Facies tracts include outer-Ramp and midRamp mudstones and wackestones, Ramp-crest grainstone shoal deposits, and extensive inner-Ramp, microbially dominated peritidal deposits. Outcrops in the Oman Mountains are deep-water deposits, including turbiditic grainstone and wackestone interbedded with siliciclastic-rich siltstone and crinkly laminite. Facies patterns and parasequence composition are variable both laterally across the outcrop area and vertically through time because of a combination of Ramp morphology, siliciclastic supply, and possible syndepositional faulting. The lithostratigraphic boundary between the Khufai Formation and the overlying Shuram Formation is gradational and represents significant flooding of the Carbonate platform. The stratigraphic characterization presented here along with the identification of key facies and diagenetic features will help further future exploration and production of hydrocarbons from the Khufai Formation.

  • digital characterization of thrombolite stromatolite reef distribution in a Carbonate Ramp system terminal proterozoic nama group namibia
    AAPG Bulletin, 2005
    Co-Authors: Erwin W Adams, John P Grotzinger, W A Watters, Stefan Schroder, David S Mccormick, Hisham A Alsiyabi
    Abstract:

    The stratigraphic architecture of a terminal Proterozoic Carbonate Ramp system (ca. 550 Ma, Nama Group, Namibia) was mapped quantitatively with digital surveying technologies. The Carbonate Ramp consists of a shoaling-upward Ramp sequence in which thrombolite-stromatolite reefs developed at several stratigraphic levels. The reefs are associated with grainstone and heterolithic facies and exhibit diverse geometries and dimensions related to the position in the sequence-stratigraphic framework. Laterally extensive reefs with a tabular geometry developed when accommodation was relatively low, whereas discontinuous oblate dome-shaped reefs developed during times when accommodation space was relatively high. Collecting sedimentological and stratigraphic data digitally in an extensive canyon system allowed a comprehensive documentation of the three-dimensional (3-D) architecture and dimensions of the reefal buildups. Both deterministic and stochastic methods were used to extend outcrop observations to construct 3-D models that honor the observed stratigraphy. In particular, the accuracy with which dimensions of reefal buildups can be measured is critically important in the statistical modeling of the dome-shaped buildups. Calculations and corrections can be applied directly to the digital data set and serve as input during model building. The final 3-D model faithfully reproduces the outcrop distribution of facies and geological objects and has a high spatial resolution, compared with petroleum industry reservoir models. The organization of the reefal buildups in the stratigraphic framework has direct implications for reservoir continuity and connectivity in analogous settings. The digital characterization and 3-D outcrop models presented in this article can be subsequently used to condition dynamic reservoir-simulation modeling of geologically similar areas.

  • geomorphic evolution of a storm dominated Carbonate Ramp c 549 ma nama group namibia
    Geological Magazine, 2005
    Co-Authors: S Dibenedetto, John P Grotzinger
    Abstract:

    The well-exposed Hoogland Member (c. 549 Ma) of the northern Nama Group (Kuibis Subgroup), Namibia, represents a storm-dominated Carbonate Ramp developed in a foreland basin of terminal Proterozoic age. The Ramp displays facies gradients involving updip grainstones which pass downdip into broad, spatially extensive tracts of microbial laminites and finely laminated mudstones deposited above and below storm wave base. Trough cross-bedded, coarse grainstones are shown to transit downdip into finer-grained calcarenites, irregular microbial laminites and mottled laminites. Siliciclastic siltstones and shales were deposited further downdip. Platform growth was terminated through smothering by orogen-derived siliciclastic deposits. Ramp morphology was controlled by several different processes which acted across many orders of magnitude (millimetres to kilometres), including in situ growth of mats and reefs, scouring by wave-produced currents, and transport and infilling of coarse-grained Carbonates and fine-grained Carbonates and clastics. At the smallest scale, ‘roughening’ of the sea-floor through heterogeneous trapping and binding by microbial mats was balanced by smoothing of the sea-floor through accumulation of loose sediment to fill the topographic lows within the upward-propagating mat. At the next scale up, parasequence development involved roughening of the sea-floor through shoal growth and grainstone progradation, balanced by sea-floor smoothing through shale infilling of resulting downdip accommodation, as well as the metre-scale topographic depressions within the mosaic of shoal-water facies. At even larger (sequence/platform) scales, roughening of the sea-floor occurred through aggradation and progradation of thick Carbonates, balanced by infilling of the foreland basin with orogen-derived siliciclastic sediments. At all scales a net balance was achieved between sea-floor roughening and sea-floor smoothing to maintain a more or less constant Ramp profile.

  • Evolution of a terminal Neoproterozoic Carbonate Ramp system (Buah Formation, Sultanate of Oman): Effects of basement paleotopography
    Geological Society of America Bulletin, 2004
    Co-Authors: Andrea Cozzi, John P Grotzinger, Philip A. Allen
    Abstract:

    The Buah Formation is a Carbonate unit of late Neoproterozoic age, exposed in the Jabal Akhdar of northern Oman and the Huqf region of central Oman. The Buah Formation is interpreted as a distally steepened storm-dominated Ramp, containing inner Ramp tidally influenced oolitic shoal and back-shoal lagoon fades and storm-dominated mid Ramp facies. A slope break separates mid-Ramp facies from outer Ramp facies characterized by accumulation of redeposited Carbonates on gently inclined slopes (1-2 degrees). Combined facies stacking patterns and outcrop correlation via δ 1 3 C profiles suggest that Buah Carbonates formed as a highstand systems tract characterized by a general upward shallowing of facies and strong lateral progradation. On a regional scale, Buah facies distributions across Oman were controlled by the presence of basement highs defining areas of reduced subsidence, which promoted lateral progradation of the Buah Carbonate Ramp for tens of kilometers, while the faster-subsiding areas became sites of deep-water deposition.

  • Understanding Carbonate Ramp dynamics using δ13C profiles: examples from the Neoproterozoic Buah Formation of Oman
    Terra Nova, 2004
    Co-Authors: Andrea Cozzi, Philip A. Allen, John P Grotzinger
    Abstract:

    The Late Neoproterozoic Buah Formation (Nafun Group, Oman) is a Carbonate unit outcropping in the Jabal Akhdar and Huqf areas. It is composed mostly of shallow-water Carbonates deposited on a distally steepened Carbonate Ramp. Correlation of two δ13C isotope shifts shows that in the Jabal Akhdar Ramp differentiation into fast and slow subsiding areas was followed by lateral progradation. In the Huqf area, however, a uniform scenario of upward shallowing of the facies and lateral progradation is demonstrated by chemostratigraphic timelines cross-cutting the facies belts. The chemostratigraphic profiles show that the Buah Formation was deposited during sea-level highstand conditions and that Ramp differentiation was due to synsedimentary tectonics. High-resolution correlation of δ13C profiles from the same lithostratigraphic unit (whether Precambrian or Phanerozoic in age) lacking biostratigraphic data can shed light on Carbonate systems dynamics, tectonic vs. eustatic controls on depositional sequences and basin subsidence.