Deformation of intrasalt beds recorded by magnetic fabrics

Funding Information Israel Science Foundation (ISF). Grant Number: 868/17 Israeli Government. Grant Number: 40706 Israel Science Foundation. Grant Number: 868/17Peer reviewedPublisher PD

Heterogeneity of folding in Zechstein (Upper Permian) salt formations in the Kłodawa Salt Structure, central Poland

Analysis of folds carried out in the Kłodawa Salt Structure (central Poland) showed that the Upper Permian (Zechstein) siliciclastic-evaporitic bed sequence is heterogeneously folded, which resulted from differences in competence of rocks and from bed stratigraphy. Rock salt and potash-rich complexes of each Zechstein cycle are internally folded and contain multiple sheath folds, interpreted as the early sheath folds, originated during lateral flow of salt. These folds are superposed by upright sheath folds inside thick PZ1-PZ2 rock salt complexes. The lack of superposed folds in younger Zechstein salt complexes (PZ3-PZ4) and unconformities between the PZ1-PZ2 and PZ3-PZ4 beds imply that rock salt beds were internally folded prior to diapirism, independently in each salt bed. Two oldest rock salt beds welded during lateral flow and were folded together into upright sheath folds during the upward flow of salt. These superposed folds clustered into subordinary diapirs and pierced through the younger deposits. The latter sunk in salt masses and formed large-scale synclinoria, consisting of beds with fossil early tectonic and sedimentary structures

Coalified bitumens from the Kłodawa Salt Structure (central Poland) as evidence on migration of hydrothermal fluids in Zechstein (Upper Permian) deposits

The paper presents the results of petrographic and geochemical studies of coaly matter occurring in Stinking Shale and Main Dolomite (PZ2, Upper Permian) deposits in the Kłodawa Salt Structure in central Poland. The coaly matter is both dispersed in the PZ2 shales and carbonates and concentrated in veins which crosscut these deposits and, depending on the location, depicts contrasting maceral composition and the rank of coal. The veins are built of colotellinite and micrinite, showing a mean random reflectance of coal in the range of 1.38–1.40%, whereas the dispersed organic matter is composed mostly of semifusinite and fusinite with minor vitrinite, showing a mean random reflectance of 0.82%. It is interpreted that the heterogeneous composition and rank of coal result from migration of hot fluids within a fracture system developed in the PZ2 shale and carbonate beds. The influx of hot fluids into the organic matter-rich beds led to the generation of bitumen which catagenetically altered along the hot fluid conduits. The coalification of bitumens took place at an early stage of tectonic deformation of the Zechstein salt series, initiated by regional extension and normal displacement on a basement fault, most probably in the Late Permian–Early Triassic

Clastic dikes and seismotectonic breccia in Permian deposits of the Nachod Basin (Middle Sudetes)

Clastic dikes have been evidenced in Permian conglomerates occurring near Kudowa Zdrój in the Nachod Basin, the Sudetes, NE Bohemian Massif. The lithology of the dikes is the same as that of the polimictic conglomerate hosting them; they only differ in textural characteristics. The spatial orientation of the dikes points out to their genetic relationship with a nearby fault that, in a map view, separates Permian and Cretaceous formations. The dikes must have intruded after tectonic rotation of conglomerate beds on the fault to a position similar to the present one and they represent record of post-diagenetic seismotectonic events

Geochemistry of hydrocarbons from the first time documented occurrence of Main Dolomite (Ca2) in the Kłodawa Salt Dome

Praca przedstawia wyniki analiz geochemicznych węglowodorów ze skał należących do ogniw dolomitu głównego (Ca2), łupku cuchnącego (T2) oraz bituminów z przecinających skały żył występujących w wysadzie solnym Kłodawy. Próby analizowano przy użyciu chromatografii gazowej sprzężonej ze spektrometrią mas (GC-MS). Zawarte w nich węglowodory pochodzą z algowego II typu kerogenu. Dolomit reprezentuje skałę macierzystą dla zawartych w nim węglowodorów, jednak nie jest wykluczona ich częściowo migracyjna geneza. Węglowodory z prób pobranych z żył i z profilu łupku cuchnącego reprezentują fazę dojrzałości z zakresu maksimum okna ropnego. Pochodzą one ze wspólnego źródła macierzystości - morskich mułów występujących w obrębie serii osadowej łupku cuchnącego. Są to pierwsze badania geochemiczne węglowodorów ze skał dolomitu głównego z wysadu solnego Kłodawy, wskazujące utwory badanej serii ilasto-węglanowo-siarczanowej jako potencjalne źródło węglowodorów w wysadzie.This paper presents the results of geochemical analysis of hydrocarbons occurring in rock formations belonging to Main Dolomite cells (Ca2) Zechstein Stinking Shale (T2) as well as bitumen found in veins intersecting the rock formations of the Kłodawa Salt Dome (central Poland). Samples were analysed using gas chromatography-mass spectrometry (GC-MS). Hydrocarbons contained in the samples derive from algal type II kerogen. Main Dolomite represents the bedrock for entrapped hydrocarbons; however, their genesis through partial migration can not be excluded. Hydrocarbons collected from the solid bitumen samples and the Stinking Shale rock originated from the same marine or lacustrine organic-poor shales and they represent a maturity level around the peak oil window. These are the first geochemical studies of hydrocarbons from Kłodawa Salt Dome Main Dolomite, which indicate that shale-carbonate-sulphate deposits are a potential source of hydrocarbons in the dome

Evolution of sheath folds around layer-parallel slip surfaces

Fałdy w złożach soli często wykazują kształt niecylindryczny. Lokalnie strukturom fałdowym towarzyszą powierzchnie odkłuć, które w niektórych przypadkach mogą być uważane za czynnik inicjujący rozwój fałdów. W artykule przedstawiono badania ewolucji kształtu fałdów futerałowych rozwijających się w warunkach ścinania prostego w sąsiedztwie powierzchni odkłucia ułożonej zgodnie z warstwowaniem. Do badań wykorzystano model analityczny opisujący deformację w otoczeniu powierzchni poślizgu w jednorodnym ośrodku lepkim. Wyniki modelowania wykazują, iż fałdy tworzące się podczas deformacji są wyraźnie niecylindryczne. Struktury ujawniające się na przekrojach prostopadłych do kierunku ścinania o charakterystycznej geometrii oczkowej wymagają odkształcenia ścięciowego γ>5, natomiast fałdy futerałowe będące szczególnym typem fałdów niecylindrycznych o wygięciu linii przegubowej przekraczającym 90º obserwowane są dla γ>10. Fałdy charakteryzują się relatywnie małą wysokością. Kształt oczek jest zwykle silnie wydłużony, a ich stosunek osi wielkiej do małej nierzadko przekracza 10. Fałdy o największej wysokości i wydłużeniu powstają w warstwach, oddalonych od powierzchni poślizgu o ok. 0,2 długości promienia tej powierzchni. Fałdy oczkowe widoczne tuż nad powierzchnią poślizgu mogą mieć U-kształtny kontur, jednakże fałdy o zarysie oczek przeważnie wykształcają się w pewnej odległości od powierzchni poślizgu, co w konsekwencji sprawia, że w naturze może być trudne zaobserwowanie związku fałdów futerałowych z powierzchniami odkłuć.Folds in evaporites typically have non-cylindrical shapes. Various fold structures are associated with slip surfaces, which, in some cases, can be interpreted as the folding trigger. In the article, we present the analysis of fold shape evolution, studying folds that develop in the vicinity of the layer-parallel slip surface during simple shear deformation. We employ an analytical model that describes the deformation around the slip surface in an isotropic, viscous material. Folds that develop during deformation are clearly non-cylindrical. Folds with an eye pattern in the sections perpendicular to the shearing directions are observed after shear strain γ>5, whereas sheath folds that are specific types of non-cylindrical folds with opening angle exceeding 90º, require γ>10. The folds are characterised by small height. The eye-shape is highly elongated, and their axial ratio commonly exceeds 10. Folds with largest height and elongation are formed in the layers located at the distance of ca. 0.2 of the slip surface radius from the slip surface. Eye structures that develop in the layers closest to the slip surface can have geometry of a concave crescent-shaped roll. Folds with the eye pattern are unlikely to develop next to the slip surfaces in the model, thus, also in the nature these two structures can hardly be noticeable in a single outcrop

Tightness of hydrogen storage caverns in salt deposits

The problem of rock salt massif tightness concerns all stored media. It is particularly important in the case of hydrogen, because of the small size of its molecules. Preliminary results of selected permeability tests performed under the project Hestor are discussed in the paper. The results of numerical calculations determining a potential range of gas leakage are also presented

Hydrocarbons in the Upper Permian PZ1– PZ2 cycles of the Kłodawa Salt Structure, central Poland

Organic geochemical studies were carried out on the sulphate–shale–carbonate series, representing the upper PZ1 and lower PZ2 sections of the Zechstein cycles in the Kłodawa Salt Structure, located in the central part of the Zechstein Basin, in Poland. Hydrocarbons extracted from the Na1 and Na2 rock salts, the A1g and A2 anhydrites, the Ca2 dolomitic anhydrite and the T2 shale-carbonate rocks were analysed by gas chromatography mass spectrometry (GC-MS). Homological series of the n-alkanes and chained isoprenes indicate the algal nature of the organic matter with the characteristic chemiistry of type II kerogen deposited under anoxic conditions. The molecular composition of other biomarkers (n-alkylbenzenes, steranes) as well as phenenthrene and dibenzothiophene and their methyl derivatives revealed the highest maturity of the hydrocarbons (level of advanced stage of the oil-window zone) in the upper part of the Stinking Shale. In the adjacent beds, a gradual decrease in the maturity of the hydrocarbons was observed both upwards and downwards in the stratigraphic sequence. The main source rock of the hydrocarbons is represented by the Stinking Shale deposits. The observed trend of vertical variation in maturity through the rock profile is explained as resulting from the continuous vertical migration of hydrocarbons, expelled during maturation from the Stinking Shale rocks into the underlying and overlying strata