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Jean-raynald De Dreuzy - One of the best experts on this subject based on the ideXlab platform.

  • Relationship of present saline fluid with paleomigration of basinal brines at the basement/sediment interface (Southeast basin - France)
    Applied Geochemistry, 2011
    Co-Authors: Luc Aquilina, Jean-raynald De Dreuzy
    Abstract:

    This paper investigates the isotopic composition (O, D, Sr, OSO4, SSO4, Cl, He) of a present saline fluid sample collected at the sediment/basement interface in the Permian continental formation at 634 m depth in the SE margin of the Massif Central shield (Ardèche margin of the Southeast basin of France). The fluid sample shows clear water-Rock interaction processes, such as feldspar dissolution and kaolinite precipitation, which have led to high Na concentrations and water stable isotopes above the local meteoric water line. The geological formations of the SE margin of the Massif Central shield show that intensive fluid circulation phases occurred across the margin from the late Triassic to the middle Jurassic. The fluids most probably originated from fluid expulsion during burial of the thick Permo-Carboniferous sedimentary succession. These circulation phases were responsible for cementation of the margin and for the solutes in the matrix microporosity which were extracted by leaching core samples. The chemical and isotopic composition of the saline fluid sample at 634 m in the Permian Rock is very similar to that of fluids in the microporosity of the Rock matrix. Their SSO4, OSO4 and Sr isotopic compositions are close to those of cements investigated in fracture fillings in the same geological formations. Simple diffusion computations and comparison of the chemical composition of the present free fluid sample with matrix porosity fluids indicate that the solutes in the present free fluid sample are related to solutes originating from fluid circulation events which occurred 160-200 Ma ago through their diffusion from the matrix microporosity. A two-stage fluid flow regime is proposed to interpret the chemistry of present and paleo-fluids. (1) During the extensional context (Permian to Cretaceous), basinal brines migrated along the basement/sediment interface after expulsion from the subsiding basin. This fluid migration would be responsible for the solutes in the Rock matrix microporosity and the solutes in the present free fluid sample. (2) Following the Alpine and Pyrenean compressive phases, gravity-driven meteoritic fluids slowly migrated from the surface down to the basement along major faults. This fluid regime would be responsible for the meteoric water collected in the present free fluid sample. Several investigations in Europe have shown that the existence of other saline fluids sampled elsewhere could be explained by these phases of fluid circulation related to specific geodynamic events.

  • Relationship of present saline fluid with paleomigration of basinal brines at the basement/sediment interface (Southeast basin – France)
    Applied Geochemistry, 2011
    Co-Authors: Luc Aquilina, Jean-raynald De Dreuzy
    Abstract:

    Abstract This paper investigates the isotopic composition (O, D, Sr, O SO 4 , S SO 4 , Cl, He) of a present saline fluid sample collected at the sediment/basement interface in the Permian continental formation at 634 m depth in the SE margin of the Massif Central shield (Ardeche margin of the Southeast basin of France). The fluid sample shows clear water–Rock interaction processes, such as feldspar dissolution and kaolinite precipitation, which have led to high Na concentrations and water stable isotopes above the local meteoric water line. The geological formations of the SE margin of the Massif Central shield show that intensive fluid circulation phases occurred across the margin from the late Triassic to the middle Jurassic. The fluids most probably originated from fluid expulsion during burial of the thick Permo-Carboniferous sedimentary succession. These circulation phases were responsible for cementation of the margin and for the solutes in the matrix microporosity which were extracted by leaching core samples. The chemical and isotopic composition of the saline fluid sample at 634 m in the Permian Rock is very similar to that of fluids in the microporosity of the Rock matrix. Their S SO 4 , O SO 4 and Sr isotopic compositions are close to those of cements investigated in fracture fillings in the same geological formations. Simple diffusion computations and comparison of the chemical composition of the present free fluid sample with matrix porosity fluids indicate that the solutes in the present free fluid sample are related to solutes originating from fluid circulation events which occurred 160–200 Ma ago through their diffusion from the matrix microporosity. A two-stage fluid flow regime is proposed to interpret the chemistry of present and paleo-fluids. (1) During the extensional context (Permian to Cretaceous), basinal brines migrated along the basement/sediment interface after expulsion from the subsiding basin. This fluid migration would be responsible for the solutes in the Rock matrix microporosity and the solutes in the present free fluid sample. (2) Following the Alpine and Pyrenean compressive phases, gravity-driven meteoritic fluids slowly migrated from the surface down to the basement along major faults. This fluid regime would be responsible for the meteoric water collected in the present free fluid sample. Several investigations in Europe have shown that the existence of other saline fluids sampled elsewhere could be explained by these phases of fluid circulation related to specific geodynamic events.

Luc Aquilina - One of the best experts on this subject based on the ideXlab platform.

  • Relationship of present saline fluid with paleomigration of basinal brines at the basement/sediment interface (Southeast basin - France)
    Applied Geochemistry, 2011
    Co-Authors: Luc Aquilina, Jean-raynald De Dreuzy
    Abstract:

    This paper investigates the isotopic composition (O, D, Sr, OSO4, SSO4, Cl, He) of a present saline fluid sample collected at the sediment/basement interface in the Permian continental formation at 634 m depth in the SE margin of the Massif Central shield (Ardèche margin of the Southeast basin of France). The fluid sample shows clear water-Rock interaction processes, such as feldspar dissolution and kaolinite precipitation, which have led to high Na concentrations and water stable isotopes above the local meteoric water line. The geological formations of the SE margin of the Massif Central shield show that intensive fluid circulation phases occurred across the margin from the late Triassic to the middle Jurassic. The fluids most probably originated from fluid expulsion during burial of the thick Permo-Carboniferous sedimentary succession. These circulation phases were responsible for cementation of the margin and for the solutes in the matrix microporosity which were extracted by leaching core samples. The chemical and isotopic composition of the saline fluid sample at 634 m in the Permian Rock is very similar to that of fluids in the microporosity of the Rock matrix. Their SSO4, OSO4 and Sr isotopic compositions are close to those of cements investigated in fracture fillings in the same geological formations. Simple diffusion computations and comparison of the chemical composition of the present free fluid sample with matrix porosity fluids indicate that the solutes in the present free fluid sample are related to solutes originating from fluid circulation events which occurred 160-200 Ma ago through their diffusion from the matrix microporosity. A two-stage fluid flow regime is proposed to interpret the chemistry of present and paleo-fluids. (1) During the extensional context (Permian to Cretaceous), basinal brines migrated along the basement/sediment interface after expulsion from the subsiding basin. This fluid migration would be responsible for the solutes in the Rock matrix microporosity and the solutes in the present free fluid sample. (2) Following the Alpine and Pyrenean compressive phases, gravity-driven meteoritic fluids slowly migrated from the surface down to the basement along major faults. This fluid regime would be responsible for the meteoric water collected in the present free fluid sample. Several investigations in Europe have shown that the existence of other saline fluids sampled elsewhere could be explained by these phases of fluid circulation related to specific geodynamic events.

  • Relationship of present saline fluid with paleomigration of basinal brines at the basement/sediment interface (Southeast basin – France)
    Applied Geochemistry, 2011
    Co-Authors: Luc Aquilina, Jean-raynald De Dreuzy
    Abstract:

    Abstract This paper investigates the isotopic composition (O, D, Sr, O SO 4 , S SO 4 , Cl, He) of a present saline fluid sample collected at the sediment/basement interface in the Permian continental formation at 634 m depth in the SE margin of the Massif Central shield (Ardeche margin of the Southeast basin of France). The fluid sample shows clear water–Rock interaction processes, such as feldspar dissolution and kaolinite precipitation, which have led to high Na concentrations and water stable isotopes above the local meteoric water line. The geological formations of the SE margin of the Massif Central shield show that intensive fluid circulation phases occurred across the margin from the late Triassic to the middle Jurassic. The fluids most probably originated from fluid expulsion during burial of the thick Permo-Carboniferous sedimentary succession. These circulation phases were responsible for cementation of the margin and for the solutes in the matrix microporosity which were extracted by leaching core samples. The chemical and isotopic composition of the saline fluid sample at 634 m in the Permian Rock is very similar to that of fluids in the microporosity of the Rock matrix. Their S SO 4 , O SO 4 and Sr isotopic compositions are close to those of cements investigated in fracture fillings in the same geological formations. Simple diffusion computations and comparison of the chemical composition of the present free fluid sample with matrix porosity fluids indicate that the solutes in the present free fluid sample are related to solutes originating from fluid circulation events which occurred 160–200 Ma ago through their diffusion from the matrix microporosity. A two-stage fluid flow regime is proposed to interpret the chemistry of present and paleo-fluids. (1) During the extensional context (Permian to Cretaceous), basinal brines migrated along the basement/sediment interface after expulsion from the subsiding basin. This fluid migration would be responsible for the solutes in the Rock matrix microporosity and the solutes in the present free fluid sample. (2) Following the Alpine and Pyrenean compressive phases, gravity-driven meteoritic fluids slowly migrated from the surface down to the basement along major faults. This fluid regime would be responsible for the meteoric water collected in the present free fluid sample. Several investigations in Europe have shown that the existence of other saline fluids sampled elsewhere could be explained by these phases of fluid circulation related to specific geodynamic events.

Jörg Hammer - One of the best experts on this subject based on the ideXlab platform.

  • Structural evolution of continental and marine Permian Rock salt of the North German Basin: constraints from microfabrics, geochemistry and U–Pb ages
    International Journal of Earth Sciences, 2020
    Co-Authors: Mareike Henneberg, Jörg Hammer, Jolien Linckens, Michael Schramm, Axel Gerdes, Gernold Zulauf
    Abstract:

    Analyzing the dynamics of microstructural response on natural deformation in Rock salt, we present microfabric, EBSD, geochemical and U–Pb data, obtained from Permian salt formations of the Kiel-Honigsee salt wall in Northern Germany. The samples were recovered from deep drillings, which penetrated through an overturned Rock salt sequence of both Rotliegend and Zechstein deposits. The bromide concentration in halite indicates a continental and marine origin for the Rotliegend and Zechstein deposits, respectively. Despite intense deformation, relics of early diagenetic fabrics are still preserved. Deformation of the impure Rotliegend Rock salt was accommodated by pressure solution and hydrofracturing as is indicated by the microfabrics and bromide concentration in halite. Fractures in siliciclastic domains were filled with fibrous halite and deformed by subgrain rotation recrystallization (SGR). Fluid-rich Zechstein Rock salt, on the other hand, was deformed by formation of subgrains and grain boundary migration (GBM). The distribution of mineral phases and fluids had a significant impact on the fabric evolution and on strain localization. U–Pb dating of carbonate phases of the Rotliegend sequence yielded Permian depositional ages and Jurassic to Cretaceous deformation ages, the latter related to diapiric ascent. The combination of results traces a dynamic evolution of the Rock fabric inside the diapir structure driven by locally active deformation processes that can be correlated with early stages of halite deposition and diagenesis and syntectonic fabric reorganization related to diapirism in an extensional setting.

  • The application of high resolution X-ray computed tomography on naturally deformed Rock salt: Multi-scale investigations of the structural inventory
    Journal of Structural Geology, 2015
    Co-Authors: Nicolas Thiemeyer, Jörg Habersetzer, M. Peinl, Gernold Zulauf, Jörg Hammer
    Abstract:

    Abstract X-ray computed tomography (CT) represents a useful technique providing new perspectives and insights for the structural investigation of naturally-deformed Rock salt. Several samples of Permian Rock salt from Gorleben, Asse and Teutschenthal (Germany) were investigated by exploiting the non-destructive nature of μCT and nCT techniques particularly for salt Rocks. CT imaging enabled the visualization and quantification of anhydrite impurities, pore space and fluid phases located along grain-boundaries or trapped as intracrystalline inclusions. Disseminated grains and aggregates of anhydrite in Rock salt of the Gorleben salt dome have been visualized and quantified by μCT for the first time in order to portray their spatial occurrence. The visualization of anhydrite aggregates and pore space shows no correlation between their spatial distributions. This independence excludes the anhydrite to be responsible for elevated porosity (0.87 ± 0.07 vol.-%). High-resolution nCT scans (≤1 μm voxel size) of single intracrystalline and grain-boundary fluid inclusions from Gorleben and Asse Rock salt allowed the visualization and quantification of their various phase components. A major achievement is the detailed description of the morphology and shape of the fluid inclusions and of their phase components, which has not been conducted in Rock salt research by high-resolution X-ray CT imaging before.

Gernold Zulauf - One of the best experts on this subject based on the ideXlab platform.

  • Structural evolution of continental and marine Permian Rock salt of the North German Basin: constraints from microfabrics, geochemistry and U–Pb ages
    International Journal of Earth Sciences, 2020
    Co-Authors: Mareike Henneberg, Jörg Hammer, Jolien Linckens, Michael Schramm, Axel Gerdes, Gernold Zulauf
    Abstract:

    Analyzing the dynamics of microstructural response on natural deformation in Rock salt, we present microfabric, EBSD, geochemical and U–Pb data, obtained from Permian salt formations of the Kiel-Honigsee salt wall in Northern Germany. The samples were recovered from deep drillings, which penetrated through an overturned Rock salt sequence of both Rotliegend and Zechstein deposits. The bromide concentration in halite indicates a continental and marine origin for the Rotliegend and Zechstein deposits, respectively. Despite intense deformation, relics of early diagenetic fabrics are still preserved. Deformation of the impure Rotliegend Rock salt was accommodated by pressure solution and hydrofracturing as is indicated by the microfabrics and bromide concentration in halite. Fractures in siliciclastic domains were filled with fibrous halite and deformed by subgrain rotation recrystallization (SGR). Fluid-rich Zechstein Rock salt, on the other hand, was deformed by formation of subgrains and grain boundary migration (GBM). The distribution of mineral phases and fluids had a significant impact on the fabric evolution and on strain localization. U–Pb dating of carbonate phases of the Rotliegend sequence yielded Permian depositional ages and Jurassic to Cretaceous deformation ages, the latter related to diapiric ascent. The combination of results traces a dynamic evolution of the Rock fabric inside the diapir structure driven by locally active deformation processes that can be correlated with early stages of halite deposition and diagenesis and syntectonic fabric reorganization related to diapirism in an extensional setting.

  • The application of high resolution X-ray computed tomography on naturally deformed Rock salt: Multi-scale investigations of the structural inventory
    Journal of Structural Geology, 2015
    Co-Authors: Nicolas Thiemeyer, Jörg Habersetzer, M. Peinl, Gernold Zulauf, Jörg Hammer
    Abstract:

    Abstract X-ray computed tomography (CT) represents a useful technique providing new perspectives and insights for the structural investigation of naturally-deformed Rock salt. Several samples of Permian Rock salt from Gorleben, Asse and Teutschenthal (Germany) were investigated by exploiting the non-destructive nature of μCT and nCT techniques particularly for salt Rocks. CT imaging enabled the visualization and quantification of anhydrite impurities, pore space and fluid phases located along grain-boundaries or trapped as intracrystalline inclusions. Disseminated grains and aggregates of anhydrite in Rock salt of the Gorleben salt dome have been visualized and quantified by μCT for the first time in order to portray their spatial occurrence. The visualization of anhydrite aggregates and pore space shows no correlation between their spatial distributions. This independence excludes the anhydrite to be responsible for elevated porosity (0.87 ± 0.07 vol.-%). High-resolution nCT scans (≤1 μm voxel size) of single intracrystalline and grain-boundary fluid inclusions from Gorleben and Asse Rock salt allowed the visualization and quantification of their various phase components. A major achievement is the detailed description of the morphology and shape of the fluid inclusions and of their phase components, which has not been conducted in Rock salt research by high-resolution X-ray CT imaging before.

Hans Thybo - One of the best experts on this subject based on the ideXlab platform.

  • Pre‐Zechstein geology of the south‐east North Sea, offshore Denmark—a geophysical perspective
    First Break, 1997
    Co-Authors: Shaohua Zhou, Hans Thybo
    Abstract:

    The aim of this paper is to present an integrated geophysical study of the pre-Zechstein geology in the south-eastern North Sea, offshore Denmark (Fig. 1). Main tectonic features of the area include the Central Graben in the west, the Horn Graben in the south-east, the East North Sea High in the middle, the Holmsland Block in the east, the southern part of the Norwegian-Danish Basin in the north, as well as the northern part of the North German Basin in the south (Fig. 2). The central part of the study area (i.e. East North Sea High) is commonly regarded as part of the Ringk˘bing-Fyn High, which is a major NWW±ESE trending positive structural element with a relatively thin cover of Mesozoic and Tertiary sediments. This structural high divides the North German Basin from the Norwegian-Danish Basin. The main tectonic features in the area are clearly illustrated by the depth structure of the top pre-Zechstein (base Upper Permian) Rock (Fig. 3a). In this study, geophysical evidence is presented to show the existence of substantial amounts of Palaeozoic sediments in the area of the East North Sea High. The interpretation is based on a residual gravity anomaly map of the region, which outlines the potential area of Palaeozoic sediments as indicated by relatively low residual gravity anomalies. Magnetic basement depths of a few selected areas are estimated using available aeromagnetic data. Interpretation of selected seismic sections is carried out to confirm the results derived from the potential field investigations. Finally, the implications of the finding of this study are discussed briefly in terms of the pre-Zechstein geology and the tectonic history of the region as well as its potential relevance to petroleum exploration in the area.