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Joe Cartwright - One of the best experts on this subject based on the ideXlab platform.
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seismic indicators of focused fluid flow and cross evaporitic seepage in the eastern mediterranean
Marine and Petroleum Geology, 2017Co-Authors: Claudia Bertoni, Joe Cartwright, Christopher Kirkham, Neil Hodgson, Karyna RodriguezAbstract:Abstract We present for the first time a synthesis of the evidence of focused fluid flow in the Eastern Mediterranean, providing an updated record that includes recent and past occurrences through the last ca. 6 My of evolution of the basin. We do this by adding the interpretation of a previously unpublished regional 2D seismic dataset to the existing occurrences of focused fluid flow reported in the literature. Our interpretation shows a high number (141) of focused fluid flow features, which span the stratigraphic interval from late Miocene to Recent. Of these features, (82) are at the seabed, and (59) are buried. The previous published record is more difficult to quantify, but in comparison shows an overwhelming majority of seabed features, with only rare examples of buried features. The spectrum of the buried and seabed features covers pockmarks, pipes, mud volcanoes, clastic intrusions and collapse structures. Clustering of the fluid flow features is observed at different times in specific areas, including the Nile Cone, and the Levant, Herodotus, Cyprus and Latakia basins. With the buried record, we are able to highlight the evolution of the leakage points through time. Focused fluid flow venting has been occurring since the onset of the Messinian Salinity Crisis and the start of basinwide deposition of Evaporites. We focus in particular on seismic indicators of leakage through Evaporites, and of sub-evaporitic source for fluids and remobilised sediments. We also discuss the role of the Evaporites as a seal to ascending fluids, and in which circumstances they can be breached. Fluids (and associated remobilised sediments) are sourced from different intervals, from the sub- and supra-evaporitic section, and possibly within the Evaporites. Only a minor proportion of the fluid flow features are certainly sourced from below the Messinian Evaporites, and most of them are located in the Nile-Levant-Eratosthenes areas. The few examples of pathways that are able to cross thick, undeformed and well preserved Evaporites are typically correlated to overpressure release and hydrofracturing. This confirms that the Evaporites do act regionally as a very good seal as expected, while fluids are able to cross the Evaporites only in their most extreme expression, i.e. in near-lithostathic overpressure conditions. This is confirmed by our observations made in the Eastern Mediterranean, where in the presence of relatively undisturbed Evaporites, cross-Evaporite vertical fluid pathways are only observed at the high end of the flux-pressure range, and involve sediment remobilisation. Maps combining these different elements can be used to detect areas potentially more prone to breaching.
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lithological control on fracture cementation in the keuper marl triassic north somerset uk
Geological Magazine, 2017Co-Authors: Qingfeng Meng, John N Hooker, Joe CartwrightAbstract:The spatial arrangement of gypsum veins as preserved natural hydraulic fractures have been characterized in the Triassic Keuper Marl Formation (UK), a caprock for hydrocarbon reservoirs and CO2 sequestration. The marls cropping out are subdivided into five discrete fracture units based on the presence and abundance of gypsum veins. The nodular gypsum in Evaporite horizons provides excess gypsum for nodule-rooted horizontal gypsum veins. Our petrographic observations demonstrate that the development of gypsum veins in beds lacking macroscopic Evaporites is closely associated with disseminated gypsum cement in the marls. We interpret that the gypsum veins in marl are sourced from disseminated gypsum cements in the host rocks, based on stratigraphic correlations, and much lower Sr concentrations than gypsum nodules. Gypsum was transported to adjacent veins mainly through diffusion in the low-permeability marls. The localization of gypsum veins and varied Sr concentrations of veins and nodules indicate that the diagenetic fluids are a mix of connate water with meteoric water rather than brines transported from Evaporite beds along faults to non-Evaporite beds. This results in the absence of gypsum fillings in fractures in rocks without primary gypsum cements. The study implies that the cementation of natural fractures in low-permeability rocks can highly depend on the presence of cement minerals in the host rock.
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The genesis of mud volcano conduits through thick Evaporite sequences
Basin Research, 2017Co-Authors: Chris Kirkham, Joe Cartwright, Christian Hermanrud, Christopher JebsenAbstract:This study documents the seismic expression of the conduits underlying over 350 mud volcanoes that were erupted in an area of the western Nile Cone in the past 5.3 Myr. The study is based on a c. 4300 km2 3D seismic survey. The conduits are interpreted to transect the >1000-m-thick Messinian Evaporite succession, demonstrating that the eruptive process is sufficiently dynamic to breach the formidable seal represented by the Evaporites. The mud volcano conduits are remarkably similar in geometry and seismic characteristics to many previously described examples of fluid escape pipes. They are vertical to subvertical structures with a crudely cylindrical geometry, but that can either widen or narrow upwards towards their upper terminations in the mud volcano edifices. Imaging at depth within the Messinian Evaporites and pre-Evaporite successions is more uncertain, but direct sampling of mud from surface volcanoes suggests a pre-Messinian source, confirming the seismic interpretation that they root within presalt stratigraphy. A conceptual model for the genesis of these mud volcano conduits through salt is proposed, for which hydraulic fracturing is driven by high overpressures that developed in the presalt source stratigraphy as a response to the Messinian Salinity Crisis. Dissolution and removal of Evaporites resulting in fracturing and collapse via a stoping mechanism is a slow process by comparison to hydraulic fracturing but is argued to potentially contribute to conduit formation. The analysis presented here demonstrates the potential for bypassing a >1-km-thick unit of sealing Evaporites via focused fluid and sediment mobilisation from deeper overpressured cells in other salt basins worldwide, and has significant implications for hydrocarbon exploration, CO2 sequestration and nuclear waste disposal.
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initiation of gravitational collapse of an Evaporite basin margin the messinian saline giant levant basin eastern mediterranean
Geological Society of America Bulletin, 2008Co-Authors: Joe Cartwright, Martin P A JacksonAbstract:Regional 2D and 3D seismic data from the Levant Basin reveal the updip extensional component of thin-skinned gravity tectonics on this continental margin. Because of its youth (5–7 Ma), the earliest stages of deformation of this salt basin are preserved without the severe structural overprinting common on more mature, giant salt-tectonic systems. Extension detaches onto and within Messinian Evaporites up to 1800 m thick. By structural restoration, we reconstruct the tectonic evolution of the Messinian Evaporites using paleobathymetric constraints from wells and seismic profiles. This analysis suggests that the Mediterranean drawdown during the Messinian Salinity Crisis was ∼800 m. The 10- to 15-km–wide extensional domain tracks the landward pinch-out of the mobile Messinian Evaporites against an older Late Miocene scarp. Diachronous extension began in the center of the margin in the mid-Pliocene, then spread northward in the late Pliocene, then finally southward in the early Pleistocene. Extension continues today on many of the most landward faults. Extensional strain varies greatly along strike from <1 km to as much as 12–15 km. Comparing observations with four end-member conceptual models, we infer that both extension and seaward salt flow thinned the Evaporite margin and its overburden. Both processes were triggered by a combination of uplift of the continental shoulder of the Dead Sea Rift and subsidence in the Mediterranean Basin. At least three factors controlled variations in extension: (1) degree of tilting of the salt wedge, related to the interplay of coastal uplift and basin subsidence; (2) presence of pre-Messinian canyons overlain by landward salients of salt; and (3) variations in Evaporite facies and the proportion of siliciclastic admixture.
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major erosion at the end of the messinian salinity crisis evidence from the levant basin eastern mediterranean
Basin Research, 2007Co-Authors: Claudia Bertoni, Joe CartwrightAbstract:This paper presents a detailed analysis of the top of the Messinian Evaporites (Horizon M) in the Levant region, offshore Israel, based on the integration of three-dimensional (3D)/2D seismic and well data. 3Dmapping of a series of intra-Evaporite horizons and their termination against HorizonM provides new insights into the depositional setting and structural evolution of this saline giant system. New evidence of a discordant relationship between the intra-Evaporite horizons and the top of theMessinian Evaporites (HorizonM) is given by the seismic stratigraphic analysis. This confirms that the top of the Messinian Evaporites represents an erosional unconformity of semiregional extent in the Levant region. The truncation of the folded and faulted intra- Evaporite horizons indicates for the first time a Messinian phase of Evaporite deformation, i.e. pre-dating the well-documented Plio- Pleistocene thin- skinned tectonic phase in the region. This major erosional unconformity is interpreted as subaerial in origin, documenting the exposure of the evaporitic systemat the end of the Messinian Salinity Crisis. These results give new evidence for the understanding of the events occurring during the last stages of the Messinian Salinity Crisis in the region.
Xiaomin Fang - One of the best experts on this subject based on the ideXlab platform.
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sedimentological and mineralogical records from drill core skd1 in the jianghan basin central china and their implications for late cretaceous early eocene climate change
Journal of Asian Earth Sciences, 2019Co-Authors: Xiaohua Teng, Xiaomin Fang, Alan J Kaufman, Jiuyi Wang, Yibo Yang, Chunlian Wang, Haiming Xu, Ruth F Schulte, Nadine M PiatakAbstract:Abstract The Jianghan Basin, Central China, contains a thick, continuous sequence of early Cenozoic Evaporite-bearing deposits that provide a wealth of information about early Cenozoic climate change and Evaporites accumulation in East Asia. However, the paleoclimatic history of the basin and its effect on the Evaporites are largely unknown. We obtained a deep drill core (SKD1, 2346.5 m long) from the late Cretaceous to early Eocene Evaporite-bearing deposits in the Jianghan Basin. Detailed analyses of the lithofacies, mineralogy and geochemistry of the core indicate that salinization and deepening of the lake occurred (corresponding to the Yuyang Formation to the lower Xingouzui Formation), followed by desalting and shallowing (corresponding to the upper Xingouzui Formation). Reconstruction of the spatiotemporal evolution of the Evaporites in the Jiangling depression suggests a transition from semi-arid conditions in the late Cretaceous to extremely arid conditions in the initial stage of the Eocene. The climate then became semi-humid during the deposition of the upper Xingouzui Formation, indicating a monsoon or monsoon-like climate in East Asia during the early Eocene. The southward migration of the depocenter of the Jiangling depression, coupled with a warm and extremely arid climate, resulted in the precipitation of Evaporites during the accumulation of the upper Shashi Formation and the lower Xingouzui Formation. These results indicate great potential for identifying potash resources within the subsag in the southern Jiangling depression.
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origins of the mid cretaceous Evaporite deposits of the sakhon nakhon basin in laos evidence from the stable isotopes of halite
Journal of Geochemical Exploration, 2018Co-Authors: Xiaomin Fang, Maodu Yan, Zengjie Zhang, Zhengrong Wang, Shurui Sun, Xiaoming LiuAbstract:Abstract The origins of the Evaporite deposits of the Khorat Plateau remain disputed. Based purely on the known evolution of the Khorat Plateau, materials of marine origin and/or remnant seawater should be present, but instead the salt layers of the deposits found there present typically continental lithological features. New data suggest that the Laotian Evaporite deposits can be dated to the Middle to Late Cretaceous. In this paper we present the sulfate δ34S (5.2‰ to 15.6‰) and δ18O-SO4 (10.3‰ to 14.1‰) records, Sr isotopic compositions (0.707443 to 0.708587), δ18O-inclusion (− 7.1‰ to 13.9‰) and δD-inclusion (− 72‰ to − 150‰) records and the trace metal elements for halite deposits extracted from Core ZK2893 in the Sakhon Nakhon Basin, Laos. These values suggest that the deposits are of continental and hydrothermal origins with trace marine remnants. Evaporites in the basins are very likely to have been formed originally by the evaporation of seawater, prior to being dissolved in meteoric water and hydrothermal fluid, and subsequently precipitated.
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origins of the mid cretaceous Evaporite deposits of the sakhon nakhon basin in laos evidence from the stable isotopes of halite
Journal of Geochemical Exploration, 2018Co-Authors: Minghui Li, Xiaomin Fang, Zengjie Zhang, Zhengrong Wang, Jiao LiAbstract:The origins of the Evaporite deposits of the Khorat Plateau remain disputed. Based purely on the known evolution of the Khorat Plateau, materials of marine origin and/or remnant seawater should be present, but instead the salt layers of the deposits found there present typically continental lithological features. New data suggest that the Laotian Evaporite deposits can be dated to the Middle to Late Cretaceous. In this paper we present the sulfate delta S-34 (5.2% to 15.6%) and delta O-18-(SO4) (10.3% to 14.1%) records, Sr isotopic compositions (0.707443 to 0.708587), delta O-18(-inclusion) (-7.1% to 13.9%) and delta D-inclusion (-72% to -150%) records and the trace metal elements for halite deposits extracted from Core ZK2893 in the Sakhon Nakhon Basin, Laos. These values suggest that the deposits are of continental and hydrothermal origins with trace marine remnants. Evaporites in the basins are very likely to have been formed originally by the evaporation of seawater, prior to being dissolved in meteoric water and hydrothermal fluid, and subsequently precipitated.
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Evaporite minerals and geochemistry of the upper 400 m sediments in a core from the western qaidam basin tibet
Quaternary International, 2010Co-Authors: Xiaomin Fang, Shaopeng Gao, Weilin Zhang, Albert GalyAbstract:Qaidam Basin is a tectonically controlled depression on the northern margin of the Tibetan Plateau. In 2008, a long core was drilled in the Qahansilatu sub-basin in the western Qaidam basin. The sediment layers in the upper 400 m alternate between Evaporite mineral layers and carbonaceous clay layers. The detailed mineralogical investigation focused on Evaporite minerals including halite, gypsum, mirabilite, thenardite, glauberite, eugsterite, and bloedite. Gypsum and halite make up the majority of the evaporate minerals. Environmentally induced variations in the mineralogy and crystal habit of the sulfates have been extensively investigated. Gypsum has prismatic and pyramid habits, such as disc pyramid, stubby prismatic, slender prismatic. Visible isolated gypsum and aggregates (rosette/radial and twins) are mostly scattered in carbonaceous clay layers, suggesting that secondary gypsum is well developed. Gypsum may be a precursor mineral of glauberite, and thenardite is the precursor of bloedite. As a metastable and rare mineral, eugsterite does not appear in other Tibetan areas. It forms at the expense of pre-existing gypsum or thenardite in the core at an experimental temperature of higher than room temperature. The presence of eugsterite indicates a warm and/or hot climate at its deposition time.
Carrillo Álvarez Emili - One of the best experts on this subject based on the ideXlab platform.
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Les Evaporites de la Conca Sud-pirinenca Oriental (Cuisià superior – Lutecià): Sedimentologia i Estructura / The Evaporites of the Southeastern Pyrenean Basin (Late Cuisian – Lutetian):Sedimentology and Structure
'Edicions de la Universitat de Barcelona', 2012Co-Authors: Carrillo Álvarez EmiliAbstract:La successió cuisiana i luteciana de la Conca Sud-pirinenca Oriental (CSO), situada al NE d’Ibèria, mostra un conjunt de sediments carbonatats, evaporítics i detrítics, els quals van ser dipositats en un context compressiu en una conca d’avantpaís. Aquesta compressió es va generar per col•lisió continental de la placa d’Ibèria i l’Europea entre el Cretaci superior i el Miocè inferior. Com a conseqüència de l’escurçament, els sediments es troben distribuïts en tres unitats estructurals: la unitat autòctona de la conca de l’Ebre, localitzada al sud, i les unitats al•lòctones del Serrat i del mantell del Cadí, ubicades al nord, situada la primera per sota de la segona. Encara que molts treballs s’han centrat en l’estudi de l’estratigrafia i l’estructura de la CSO, l’arquitectura estratigràfica i els ambients deposicionals de les Evaporites no s’han acabat de resoldre. Les roques evaporítiques dipositades en conques d’avantpaís actuen, en molts casos, com a nivells de desenganxament i, per tant, aquestes roques estan deformades o simplement no afloren. Com a conseqüència, el coneixement d’aquests dipòsits no és molt ampli, i l’estudi d’afloraments i litofàcies resulta un repte. L’objectiu general d’aquesta tesi és millorar aquest coneixement. En aquesta tesi, a partir de la realització de mapes i talls geològics detallats, i de la correlació de columnes i logs de pous, s’ha establert l’arquitectura estratigràfica de la CSO per als períodes Cuisià superior i Lutecià. Aquesta arquitectura presenta sis seqüències deposicionals, tres de les quals de nova proposta en el present treball. Aquestes tres seqüències corresponen a la seqüència Serrat, formada per les Evaporites del Serrat, i a les seqüències Bellmunt inferior i superior, constituïdes per sediments detrítics. Les Evaporites del Serrat, dipositades per sobre d’una primera seqüència carbonatada (formacions Penya i Armàncies), es caracteritzen per tenir capes de sals i lutites en un depocentre situat actualment en el mantell del Cadí. Aquestes sals estan envoltades per un cinturó marginal anhidrític, localitzat en la conca de l’Ebre. En el centre de la conca, aquestes Evaporites estan cobertes per una successió turbidítica atribuïda a la Formació Vallfogona (seqüència Campdevànol) en diferents depocentres. Cap als marges de la conca, aquesta formació canvia lateralment a unitats carbonatades (Calcàries de la Pedra i Calcisiltites). La Formació Guixos de Beuda es troba per sobre de la seqüència Campdevànol, i representa la segona seqüència evaporítica. Les seqüències Bellmunt inferior i superior, caracteritzades per dipòsits d’origen fluviodeltaic (formacions Banyoles, Coubet i Bellmunt), representen les seqüències més modernes d’aquesta arquitectura. Aquestes dues seqüències estan separades per una altra unitat evaporítica, anomenada en el present treball Guixos de Besalú. S’ha reconegut que la potència de les capes d’anhidrites atribuïdes a les Evaporites del Serrat és major en la conca de l’Ebre que en el mantell del Cadí. Per tant, s’ha considerat que aquesta unitat es configura, de la conca de l’Ebre fins al mantell del Cadí, com a un tascó anhidrític que passa a una cubeta salina en el centre de la conca. Per contra, també s’ha reconegut que la potència de la Formació Beuda és menor a la conca de l’Ebre que en el mantell del Cadí. L’anàlisi de mostres d’afloraments i de testimonis de pous ha permès interpretar els models sedimentaris de les unitats evaporítiques més representatives. En les Evaporites del Serrat, s’han distingit tres paleoambients, de marge a centre de conca: plataforma sulfatada, constituïda per anhidrita nodular i pseudomòrfica (de selenites); talús, format per guix secundari (anhidrita en profunditat) amb litofàcies laminada, de caràcter detrític; i conca profunda, constituïda per capes de sal i lutites reconegudes només en el subsòl. En canvi, en la Formació Beuda només s’ha reconegut un únic paleoambient, corresponent a un sistema de conca sulfatada situat en el mantell del Cadí. Aquest paleoambient està representat per cicles de guix secundari (anhidrita en profunditat) amb litofàcies massives i nivells pseudomòrfics (de selenites). De tota manera, l’existència d’àrees amb litofàcies bandades i laminades, atribuïdes a ambients més profunds, indiquen l’existència de petites zones més deprimides en la conca. La composició isotòpica (delta-34S, delta-18O; 87Sr/86Sr) de mostres de guix i anhidrita indiquen un origen marí per aquestes unitats i, a més, processos de dissolució/reprecipitació dels sulfats. A partir de l’anàlisi estructural de les correlacions estratigràfiques, dels mapes i talls geològics, de la interpretació de perfils sísmics reprocessats i de noves dades gravimètriques s’ha deduït que la sedimentació durant el Cuisià superior i Lutecià va tenir dues etapes tectòniques: una primera etapa extensiva, coetània amb la sedimentació de les Evaporites del Serrat i la Formació Vallfogona, i caracteritzada per falles normals produïdes per flexió extensional; i una segona etapa compressiva, sincrònica a la sedimentació fluviodeltaica, i caracteritzada per encavalcaments i plecs, i falles transversals de tipus strike-slip. Durant la primera etapa, les falles normals van tenir direccions obliqües i perpendiculars respecte l’escurçament pirinenc (N-S). Durant la segona etapa, les falles de strike-slip van estar generades per la reactivació de falles normals preexistents. A més, les Evaporites del Serrat van actuar com a nivell de desenganxament del mantell del Cadí i de la Unitat Serrat. Finalment, en aquesta tesi, s’han realitzat models sandbox per tal de millorar el coneixement del paper de l’arquitectura estratigràfica d’una successió dúctil (en aquest cas, Evaporites) sobre l’evolució estructural. A partir d’una sèrie d’experiments, s’ha observat que l’existència de discontinuïtats geomètriques en els materials anàlegs a les litologies evaporítiques generen zones de deformació preferencial. Comparant els resultats d’aquests experiments amb els trets estructurals de la CSO, s’ha interpretat que l’evolució i estil estructural d’aquesta conca va estar controlada per l’existència de discontinuïtats litològiques –com el canvi de gruix de les anhidrites entre la plataforma evaporítica i la conca profunda– en les Evaporites del Serrat. L’existència d’aquestes discontinuïtats litològiques va generar encavalcaments fora de seqüència, contribuint a la generació d’una conca de piggyback.The Cuisian and Lutetian succession of the Southeastern Pyrenean Basin (SePB), NE of Iberia, shows an assemblage of carbonate, Evaporite and detrital sediments, deposited under a compressional context in a foreland basin. The compression was generated by continental collision of the Iberian and the European plates during the time span comprised between the Upper Cretaceous and the Lower Miocene. As a consequence of the shortening, these deposits were distributed in three structural units: the autochthonous unit of the Ebro Basin, located to the south; and the allochthonous units of the Serrat Unit (below) and the Cadí thrust sheet (above), placed to the north. Despite many studies have been focused on the stratigraphy and the structure of the SePB, the stratigraphic framework and the depositional environments of the Evaporites remain poorly understood. In foreland basins, the Evaporite rocks usually act as décollement levels, so they are deformed or simply are not outcropping. As a consequence, the knowledge of these deposits is limited, and the study of outcrops and lithofacies is a challenge. The general aim of the present Ph.D. Thesis is to improve this knowledge. In this Ph.D. Thesis, on the basis of geological maps, cross-sections, and sections and welllogs correlations, a stratigraphic framework of the SePB was established for the Late Cuisian and Lutetian times. This framework considers six depositional sequences, and three of them are newly proposed. These three sequences correspond to the Serrat sequence, formed by the Serrat Evaporites, and the Lower and Upper Bellmunt sequences, constituted by detrital sediments. The Serrat Evaporites, deposited on a previous carbonate sequence (Penya and Armàncies formations), are characterized by salt – shale layers in a depocenter located basinward (nowadays in the Cadí thrust sheet). These salt layers are surrounded by an anhydrite marginal belt, placed in the Ebro Basin. In the basin center, these Evaporites are covered by turbidite successions attributed to the Vallfogona Formation (Campdevànol sequence) in different depocenters. To the margins, this formation changes laterally to carbonate deposits (Pedra Limestones and Calcisiltites). The Beuda Gypsum Formation is overlying the Campdevànol sequence, and represents the second Evaporite sequence. The Lower and Upper Bellmunt sequences, characterized by fluvio-deltaic deposits (Banyoles, Coubet and Bellmunt formations), are the youngest sequences of this succession. These two sequences are divided by another Evaporite unit, called Besalú Gypsum in the present work. The anhydrite layers attributed to the Serrat Evaporites were recognized to be thicker in the Ebro Basin than in the Cadí thrust sheet. Thus, the stratigraphic framework of this unit is characterized, from the Ebro Basin to the Cadí thrust sheet, by an anhydrite wedge which changes to a salt deposit in the basin center. By contrast, the Beuda Formation was recognized to be thinner in the Ebro Basin than in the Cadí thrust sheet. The analysis of samples and well-cores allowed to interpret the sedimentary models of the most representative Evaporite units. Three paleoenvironments were distinguished in the Serrat Evaporites, from the margin to the basin center: sulphate platform, constituted by anhydrite nodules and pseudomorphs (after selenite gypsum); slope, formed by secondary gypsum (anhydrite in the subsurface) with laminated, detrital lithofacies; and deep basin, constituted by salt and shale layers, only recognized in the subsurface. On the other hand, in the Beuda Formation, only one paleoenvironment, characterized by a sulphate basin, was recognized in the Cadí thrust sheet. This paleoenvironment is represented by cycles of secondary gypsum (anhydrite in the subsurface) with massive and pseudomorphic (after selenite gypsum) lithofacies. However, the existence of areas with banded and laminated lithofacies, attributed to deeper environments, indicates the occurence of small troughs in the basin. The isotopic composition (delta-34S, delta-18O; 87Sr/86Sr) of gypsum and anhydrite samples indicates a marine origin of these units and, also, dissolution/re-precipitation processes of the sulphates. On the basis of the structural analysis of the stratigraphic correlations, the geological maps, the cross-sections, the interpretation of reprocessed seismic profiles and new gravity data, it was deduced that the sedimentation during the Late Cuisian and Lutetian had two tectonic stages: a first extensive stage, coeval to the sedimentation of the Serrat Evaporites and the Vallfogona Formation, and characterized by normal faults generated by flexural extension; and a second compressional stage, coeval to the fluvio-deltaic sedimentation, and characterized by fold-and-thrust and transverse strike-slip faults. During the first stage, the normal faults had oblique and perpendicular directions with respect to the Pyrenean shortening (N-S). During the second stage, the strike-slip faults were generated by reactivation of pre-existing normal faults. Also, the Serrat Evaporites acted as the décollement level of both the Cadí thrust sheet and the Serrat Unit. Finally, in this Ph.D. Thesis, in order to improve the knowledge about the role of the stratigraphic framework of a ductile succession (Evaporites, in this case) on the structural evolution, sandbox models were developed. On the basis of a series of experiments, it was observed that the existence of geometrical discontinuities, located in materials analogue of the Evaporites, generates zones of preferential deformation. Comparing the results of these experiments with the structural features of the SePB, it was interpreted that the evolution and the structural style of this basin was controlled by the existence of lithological discontinuities –as the case of the thickness change of the anhydrites between the Evaporite platform and the deep basin– in the Serrat Evaporites. The existence of these lithological discontinuities generated out of sequence thrusts, contributing to the development of a piggyback basin
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Les Evaporites de la Conca Sud-pirinenca Oriental (Cuisià superior – Lutecià): Sedimentologia i Estructura / The Evaporites of the Southeastern Pyrenean Basin (Late Cuisian – Lutetian):Sedimentology and Structure
'Edicions de la Universitat de Barcelona', 2012Co-Authors: Carrillo Álvarez EmiliAbstract:[cat] La successió cuisiana i luteciana de la Conca Sud-pirinenca Oriental (CSO), situada al NE d’Ibèria, mostra un conjunt de sediments carbonatats, evaporítics i detrítics, els quals van ser dipositats en un context compressiu en una conca d’avantpaís. Aquesta compressió es va generar per col•lisió continental de la placa d’Ibèria i l’Europea entre el Cretaci superior i el Miocè inferior. Com a conseqüència de l’escurçament, els sediments es troben distribuïts en tres unitats estructurals: la unitat autòctona de la conca de l’Ebre, localitzada al sud, i les unitats al•lòctones del Serrat i del mantell del Cadí, ubicades al nord, situada la primera per sota de la segona. Encara que molts treballs s’han centrat en l’estudi de l’estratigrafia i l’estructura de la CSO, l’arquitectura estratigràfica i els ambients deposicionals de les Evaporites no s’han acabat de resoldre. Les roques evaporítiques dipositades en conques d’avantpaís actuen, en molts casos, com a nivells de desenganxament i, per tant, aquestes roques estan deformades o simplement no afloren. Com a conseqüència, el coneixement d’aquests dipòsits no és molt ampli, i l’estudi d’afloraments i litofàcies resulta un repte. L’objectiu general d’aquesta tesi és millorar aquest coneixement. En aquesta tesi, a partir de la realització de mapes i talls geològics detallats, i de la correlació de columnes i logs de pous, s’ha establert l’arquitectura estratigràfica de la CSO per als períodes Cuisià superior i Lutecià. Aquesta arquitectura presenta sis seqüències deposicionals, tres de les quals de nova proposta en el present treball. Aquestes tres seqüències corresponen a la seqüència Serrat, formada per les Evaporites del Serrat, i a les seqüències Bellmunt inferior i superior, constituïdes per sediments detrítics. Les Evaporites del Serrat, dipositades per sobre d’una primera seqüència carbonatada (formacions Penya i Armàncies), es caracteritzen per tenir capes de sals i lutites en un depocentre situat actualment en el mantell del Cadí. Aquestes sals estan envoltades per un cinturó marginal anhidrític, localitzat en la conca de l’Ebre. En el centre de la conca, aquestes Evaporites estan cobertes per una successió turbidítica atribuïda a la Formació Vallfogona (seqüència Campdevànol) en diferents depocentres. Cap als marges de la conca, aquesta formació canvia lateralment a unitats carbonatades (Calcàries de la Pedra i Calcisiltites). La Formació Guixos de Beuda es troba per sobre de la seqüència Campdevànol, i representa la segona seqüència evaporítica. Les seqüències Bellmunt inferior i superior, caracteritzades per dipòsits d’origen fluviodeltaic (formacions Banyoles, Coubet i Bellmunt), representen les seqüències més modernes d’aquesta arquitectura. Aquestes dues seqüències estan separades per una altra unitat evaporítica, anomenada en el present treball Guixos de Besalú. S’ha reconegut que la potència de les capes d’anhidrites atribuïdes a les Evaporites del Serrat és major en la conca de l’Ebre que en el mantell del Cadí. Per tant, s’ha considerat que aquesta unitat es configura, de la conca de l’Ebre fins al mantell del Cadí, com a un tascó anhidrític que passa a una cubeta salina en el centre de la conca. Per contra, també s’ha reconegut que la potència de la Formació Beuda és menor a la conca de l’Ebre que en el mantell del Cadí. L’anàlisi de mostres d’afloraments i de testimonis de pous ha permès interpretar els models sedimentaris de les unitats evaporítiques més representatives. En les Evaporites del Serrat, s’han distingit tres paleoambients, de marge a centre de conca: plataforma sulfatada, constituïda per anhidrita nodular i pseudomòrfica (de selenites); talús, format per guix secundari (anhidrita en profunditat) amb litofàcies laminada, de caràcter detrític; i conca profunda, constituïda per capes de sal i lutites reconegudes només en el subsòl. En canvi, en la Formació Beuda només s’ha reconegut un únic paleoambient, corresponent a un sistema de conca sulfatada situat en el mantell del Cadí. Aquest paleoambient està representat per cicles de guix secundari (anhidrita en profunditat) amb litofàcies massives i nivells pseudomòrfics (de selenites). De tota manera, l’existència d’àrees amb litofàcies bandades i laminades, atribuïdes a ambients més profunds, indiquen l’existència de petites zones més deprimides en la conca. La composició isotòpica (delta-34S, delta-18O; 87Sr/86Sr) de mostres de guix i anhidrita indiquen un origen marí per aquestes unitats i, a més, processos de dissolució/reprecipitació dels sulfats. A partir de l’anàlisi estructural de les correlacions estratigràfiques, dels mapes i talls geològics, de la interpretació de perfils sísmics reprocessats i de noves dades gravimètriques s’ha deduït que la sedimentació durant el Cuisià superior i Lutecià va tenir dues etapes tectòniques: una primera etapa extensiva, coetània amb la sedimentació de les Evaporites del Serrat i la Formació Vallfogona, i caracteritzada per falles normals produïdes per flexió extensional; i una segona etapa compressiva, sincrònica a la sedimentació fluviodeltaica, i caracteritzada per encavalcaments i plecs, i falles transversals de tipus strike-slip. Durant la primera etapa, les falles normals van tenir direccions obliqües i perpendiculars respecte l’escurçament pirinenc (N-S). Durant la segona etapa, les falles de strike-slip van estar generades per la reactivació de falles normals preexistents. A més, les Evaporites del Serrat van actuar com a nivell de desenganxament del mantell del Cadí i de la Unitat Serrat. Finalment, en aquesta tesi, s’han realitzat models sandbox per tal de millorar el coneixement del paper de l’arquitectura estratigràfica d’una successió dúctil (en aquest cas, Evaporites) sobre l’evolució estructural. A partir d’una sèrie d’experiments, s’ha observat que l’existència de discontinuïtats geomètriques en els materials anàlegs a les litologies evaporítiques generen zones de deformació preferencial. Comparant els resultats d’aquests experiments amb els trets estructurals de la CSO, s’ha interpretat que l’evolució i estil estructural d’aquesta conca va estar controlada per l’existència de discontinuïtats litològiques –com el canvi de gruix de les anhidrites entre la plataforma evaporítica i la conca profunda– en les Evaporites del Serrat. L’existència d’aquestes discontinuïtats litològiques va generar encavalcaments fora de seqüència, contribuint a la generació d’una conca de piggyback.[eng] The Cuisian and Lutetian succession of the Southeastern Pyrenean Basin (SePB), NE of Iberia, shows an assemblage of carbonate, Evaporite and detrital sediments, deposited under a compressional context in a foreland basin. The compression was generated by continental collision of the Iberian and the European plates during the time span comprised between the Upper Cretaceous and the Lower Miocene. As a consequence of the shortening, these deposits were distributed in three structural units: the autochthonous unit of the Ebro Basin, located to the south; and the allochthonous units of the Serrat Unit (below) and the Cadí thrust sheet (above), placed to the north. Despite many studies have been focused on the stratigraphy and the structure of the SePB, the stratigraphic framework and the depositional environments of the Evaporites remain poorly understood. In foreland basins, the Evaporite rocks usually act as décollement levels, so they are deformed or simply are not outcropping. As a consequence, the knowledge of these deposits is limited, and the study of outcrops and lithofacies is a challenge. The general aim of the present Ph.D. Thesis is to improve this knowledge. In this Ph.D. Thesis, on the basis of geological maps, cross-sections, and sections and welllogs correlations, a stratigraphic framework of the SePB was established for the Late Cuisian and Lutetian times. This framework considers six depositional sequences, and three of them are newly proposed. These three sequences correspond to the Serrat sequence, formed by the Serrat Evaporites, and the Lower and Upper Bellmunt sequences, constituted by detrital sediments. The Serrat Evaporites, deposited on a previous carbonate sequence (Penya and Armàncies formations), are characterized by salt – shale layers in a depocenter located basinward (nowadays in the Cadí thrust sheet). These salt layers are surrounded by an anhydrite marginal belt, placed in the Ebro Basin. In the basin center, these Evaporites are covered by turbidite successions attributed to the Vallfogona Formation (Campdevànol sequence) in different depocenters. To the margins, this formation changes laterally to carbonate deposits (Pedra Limestones and Calcisiltites). The Beuda Gypsum Formation is overlying the Campdevànol sequence, and represents the second Evaporite sequence. The Lower and Upper Bellmunt sequences, characterized by fluvio-deltaic deposits (Banyoles, Coubet and Bellmunt formations), are the youngest sequences of this succession. These two sequences are divided by another Evaporite unit, called Besalú Gypsum in the present work. The anhydrite layers attributed to the Serrat Evaporites were recognized to be thicker in the Ebro Basin than in the Cadí thrust sheet. Thus, the stratigraphic framework of this unit is characterized, from the Ebro Basin to the Cadí thrust sheet, by an anhydrite wedge which changes to a salt deposit in the basin center. By contrast, the Beuda Formation was recognized to be thinner in the Ebro Basin than in the Cadí thrust sheet. The analysis of samples and well-cores allowed to interpret the sedimentary models of the most representative Evaporite units. Three paleoenvironments were distinguished in the Serrat Evaporites, from the margin to the basin center: sulphate platform, constituted by anhydrite nodules and pseudomorphs (after selenite gypsum); slope, formed by secondary gypsum (anhydrite in the subsurface) with laminated, detrital lithofacies; and deep basin, constituted by salt and shale layers, only recognized in the subsurface. On the other hand, in the Beuda Formation, only one paleoenvironment, characterized by a sulphate basin, was recognized in the Cadí thrust sheet. This paleoenvironment is represented by cycles of secondary gypsum (anhydrite in the subsurface) with massive and pseudomorphic (after selenite gypsum) lithofacies. However, the existence of areas with banded and laminated lithofacies, attributed to deeper environments, indicates the occurence of small troughs in the basin. The isotopic composition (delta-34S, delta-18O; 87Sr/86Sr) of gypsum and anhydrite samples indicates a marine origin of these units and, also, dissolution/re-precipitation processes of the sulphates. On the basis of the structural analysis of the stratigraphic correlations, the geological maps, the cross-sections, the interpretation of reprocessed seismic profiles and new gravity data, it was deduced that the sedimentation during the Late Cuisian and Lutetian had two tectonic stages: a first extensive stage, coeval to the sedimentation of the Serrat Evaporites and the Vallfogona Formation, and characterized by normal faults generated by flexural extension; and a second compressional stage, coeval to the fluvio-deltaic sedimentation, and characterized by fold-and-thrust and transverse strike-slip faults. During the first stage, the normal faults had oblique and perpendicular directions with respect to the Pyrenean shortening (N-S). During the second stage, the strike-slip faults were generated by reactivation of pre-existing normal faults. Also, the Serrat Evaporites acted as the décollement level of both the Cadí thrust sheet and the Serrat Unit. Finally, in this Ph.D. Thesis, in order to improve the knowledge about the role of the stratigraphic framework of a ductile succession (Evaporites, in this case) on the structural evolution, sandbox models were developed. On the basis of a series of experiments, it was observed that the existence of geometrical discontinuities, located in materials analogue of the Evaporites, generates zones of preferential deformation. Comparing the results of these experiments with the structural features of the SePB, it was interpreted that the evolution and the structural style of this basin was controlled by the existence of lithological discontinuities –as the case of the thickness change of the anhydrites between the Evaporite platform and the deep basin– in the Serrat Evaporites. The existence of these lithological discontinuities generated out of sequence thrusts, contributing to the development of a piggyback basin
Jean-claude Ringenbach - One of the best experts on this subject based on the ideXlab platform.
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characterization of oligo miocene Evaporite rich minibasins in the sivas basin turkey
Marine and Petroleum Geology, 2019Co-Authors: A. Pichat, Guilhem Hoareau, Jean-paul Callot, Jean-claude RingenbachAbstract:Abstract The Sivas Basin in Turkey displays in its central part an Oligo-Miocene halokinetic province which acts as a major outcrop analogue to study salt-sediment interactions. Based on field geology observations, the present paper focuses on the geometry and sedimentology of several minibasins having the particularity of being mainly filled by gypsiferous deposits. Such type of Evaporite-rich minibasins remain difficult to identify and are poorly studied in other halokinetic provinces. In the Sivas Basin, the Evaporites were recycled from diapiric salts and precipitated in saline ponds emplaced above deflating diapiric stems. Diapir deflation resulted either from local transtensive strain, cessation of diapir feeding and/or subsurface dissolution of the diapiric salt. Minibasin subsidence was likely enhanced by the fast emplacement rate of the capping Evaporites, together with the high density of the depositional sulfates compared to the diapiric halite. The Evaporite-rich minibasins stand out from their surrounding siliciclastic counter-parts by their small dimension (lower than 1 km-wide), their encased teardrop shape, and their high internal deformations. The later include well-developed halokinetic sedimentary wedges, aerial mega-slumps or inverted flaps. Such structural features probably resulted from the ductile rheology of the Evaporite infill and the complex pattern of downbuilding. Although secondary evaporitic minibasins have never been identified in other ancient halokinetic settings, our study highlights that they could developed in any evaporitic environments, coastal or continental, such as in the Precaspian Basin. The secondary minibasins described here can also act as field analogues of other primary Evaporite-rich minibasins already suspected in salt giant basins (e.g. in the Santos Basin, Brazil).
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Evidence of multiple Evaporite recycling processes in a salt-tectonic context, Sivas Basin, Turkey
Terra Nova, 2017Co-Authors: A. Pichat, Guilhem Hoareau, Etienne Legeay, K.s. Kavak, Sidonie Revillon, Corinne Parat, Jean-paul Callot, Jean-claude RingenbachAbstract:The isotopic composition of Evaporites can shed light on their environment of precipitation and their subsequent recycling processes. In this study, we performed Sr, O and S isotopic analyses on evaporitic sulphates in the halokinetic Sivas Basin. The main objectives were to decipher the age and origin of the Evaporites responsible for the salt tectonics, and to test whether diapir dissolution acts as the source of younger evaporitic layers in continental mini-basins. The Sr isotopes demonstrate that the first Evaporites precipitated from seawater during the Middle–Late Eocene. The similar isotopic values measured in the halokinetic domain confirm that the Eocene Evaporites triggered the salt tectonics and were continuously recycled in Oligo-Miocene mini-basins as lacustrine to sabkha Evaporites. Modern halite precipitates suggest that the dissolution and recycling of diapiric halite is ongoing. This study demonstrates the efficiency of isotopic analyses in constraining Evaporite recycling processes in continental halokinetic domains. This article is protected by copyright. All rights reserved.
A. Pichat - One of the best experts on this subject based on the ideXlab platform.
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characterization of oligo miocene Evaporite rich minibasins in the sivas basin turkey
Marine and Petroleum Geology, 2019Co-Authors: A. Pichat, Guilhem Hoareau, Jean-paul Callot, Jean-claude RingenbachAbstract:Abstract The Sivas Basin in Turkey displays in its central part an Oligo-Miocene halokinetic province which acts as a major outcrop analogue to study salt-sediment interactions. Based on field geology observations, the present paper focuses on the geometry and sedimentology of several minibasins having the particularity of being mainly filled by gypsiferous deposits. Such type of Evaporite-rich minibasins remain difficult to identify and are poorly studied in other halokinetic provinces. In the Sivas Basin, the Evaporites were recycled from diapiric salts and precipitated in saline ponds emplaced above deflating diapiric stems. Diapir deflation resulted either from local transtensive strain, cessation of diapir feeding and/or subsurface dissolution of the diapiric salt. Minibasin subsidence was likely enhanced by the fast emplacement rate of the capping Evaporites, together with the high density of the depositional sulfates compared to the diapiric halite. The Evaporite-rich minibasins stand out from their surrounding siliciclastic counter-parts by their small dimension (lower than 1 km-wide), their encased teardrop shape, and their high internal deformations. The later include well-developed halokinetic sedimentary wedges, aerial mega-slumps or inverted flaps. Such structural features probably resulted from the ductile rheology of the Evaporite infill and the complex pattern of downbuilding. Although secondary evaporitic minibasins have never been identified in other ancient halokinetic settings, our study highlights that they could developed in any evaporitic environments, coastal or continental, such as in the Precaspian Basin. The secondary minibasins described here can also act as field analogues of other primary Evaporite-rich minibasins already suspected in salt giant basins (e.g. in the Santos Basin, Brazil).
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Evidence of multiple Evaporite recycling processes in a salt-tectonic context, Sivas Basin, Turkey
Terra Nova, 2017Co-Authors: A. Pichat, Guilhem Hoareau, Etienne Legeay, K.s. Kavak, Sidonie Revillon, Corinne Parat, Jean-paul Callot, Jean-claude RingenbachAbstract:The isotopic composition of Evaporites can shed light on their environment of precipitation and their subsequent recycling processes. In this study, we performed Sr, O and S isotopic analyses on evaporitic sulphates in the halokinetic Sivas Basin. The main objectives were to decipher the age and origin of the Evaporites responsible for the salt tectonics, and to test whether diapir dissolution acts as the source of younger evaporitic layers in continental mini-basins. The Sr isotopes demonstrate that the first Evaporites precipitated from seawater during the Middle–Late Eocene. The similar isotopic values measured in the halokinetic domain confirm that the Eocene Evaporites triggered the salt tectonics and were continuously recycled in Oligo-Miocene mini-basins as lacustrine to sabkha Evaporites. Modern halite precipitates suggest that the dissolution and recycling of diapiric halite is ongoing. This study demonstrates the efficiency of isotopic analyses in constraining Evaporite recycling processes in continental halokinetic domains. This article is protected by copyright. All rights reserved.