Shocked quartz : impact eyewitness wanted

Most of the craters on the Earth, produced by an impact of meteorite or other space object, have been masked by exogenous processes. Therefore, indirect indicators of the impact such as shocked quartz have been recognized. The impact metamorphism is visibly recorded within quartz by distinctive microstructures. However, only the planar deformation features (PDF) are unquestionable evidences of impact. They should be investigated with particular accuracy because of similarity to endogenic planar microdeformations such as: growth features or metamorphic deformation lamellae. The K/Pg boundary interval from the Polish Outer Carpathians (Skole Unit, Husów. Thrust Sheet, B¹kowiec section) have been studied. This note presents difficulties in identifying shock features in quartz grains collected from turbiditic material

Depositional redox conditions of the Grybów Succession (Oligocene, Polish Carpathians) in the light of petrological and geochemical indices

This study details the petrology and chemistry of the Oligocene succession of the Grybów Nappe in its stratotype-locality in the Grybów tectonic window (Polish Carpathians). The section studied is composed of the Sub-Grybów Beds, the Grybów Marl Formation (GMF), and the Cergowa Beds, representing the middle to upper part of the Oligocene succession. The rocks studied consist of quartz, calcite, Na-plagioclase, muscovite and clay minerals (illite-smectite with 25–30% of smectite and kaolinite). Additionally, hematite occurs in the GMF and chlorite in the Cergowa Beds, respectively. The macerals assemblage of the GMF is dominated by landplant-derived compounds of liptinite, associated with minor amounts of vitrinite representing type II kerogen. The total organic carbon (TOC) content is between 0.45 and 6.16 wt.%. The δ13Corg values of the GMF vary between –27.1 and –27.9‰. The values of both carbon and oxygen isotopic ratios of carbonates range for δ13C from –1.1 to –4.3‰ VPDB, and for O from –1.5 to –4.8‰ VPDB. The concentrations of Co, U, Ni, As, and Mo are higher in the GMF than in the adjacent strata and positively correlate with TOC and S. Values of the TOC/S and V/V+Ni ratios are 0.7 to 3.5 and 0.67 to 0.78, respectively, and indicate anoxic conditions. The ratios of U/Th and V/Cr (0.3–2.2, 1.18–3.18, respectively) suggest the change of oxic conditions to reducing conditions occurred during the GMF deposition. This change could have been preceded by a plankton bloom, initiated by a nutrient-rich freshwater inflow that is inferred from the decrease of the δ13Ccarbvalues and the terrestrial detritus supply. Thermal alteration of the Grybów Succession is concluded on the basis of smectite illitisation and low δ18O values

Elemental and organic carbon proxies for redox conditions of the Oligocene formations in the Ropa Tectonic Window (Outer Carpathians, Poland) : palaeoenvironmental implications

The Oligocene Grybów Succession is recognized as a counterpart of the anoxic Menilite Formation. Its comprehensive geochemical investigations are made in the key sections of the Ropa Tectonic Window (the Grybów Unit, Polish Outer Carpathians). The maceral assemblages, dominated by land-plant liptinite, vitrinite and intertinite, correspond to kerogen types II and III. A T_{max} vs. HI diagram shows terrestrial kerogen type II with various additions of type III and algal kerogen type I. A variation in \delta^{13}C_{org.} (from -25.21 to -27.38‰) may have resulted from variations in the composition of organic matter (the content of terrestrial vs. marine organic matter), controlled by depositional setting (turbidite vs. hemipelagic). The highest TOC contents are associated with an enhanced influx of land-derived organic matter. The redox-sensitive trace elements positively correlate with TOC and TS contents. Redox conditions varied between oxic and anoxic, as was concluded from TOC-TS, V/(V+Ni) and U/Th. The turbidity currents might have ventilated the bottom waters, especially more efficiently in the proximal zone of turbidite sedimentation. Moreover, oxygenated bottom waters may have also affected the concentration of trace metals, owing to migration of the redox interface downward within the sediments

Organic carbon accumulation events in the mid-Cretaceous rocks of the Pieniny Klippen Belt (Polish Carpathians) : a petrological and geochemical approach

New petrological and geochemical data lead to a consistent depositional model of the $C_{org.}$-rich sedimentation within the Pieniny Basin during the mid-Cretaceous. Considerable terrestrial runoff into the Pieniny Basin occurred during the late Albian. Detrital macerals accumulated under aerobic conditions on the shelf and continental slope. Fertilization of surface water induced primary productivity; aerobic degradation of organic matter led to the development of an oxygen-minimum zone within mid-water. The oxygen-minimum zone spread over almost all of the Pieniny Basin (Albian/Cenomanian). At the same time, a stagnant pool developed in the Grajcarek Basin. During the mid-Cenomanian the $O_{2}$ minimum zone retracted and covered only the shelf and upper/middle slope. Stagnant pools might have formed in the depressions. Turbidity currents flowed down the slope and deposited calciturbiditic sequences with organic detritus in the Branisko and Pieniny basins. At the end of the Cenomanian, isolated anoxic or even $H_{2}S$-bearing basins existed on the shelf. The slope was still occupied by the oxygen-minimum zone. In the deepest part of the sea-floor a stagnant basin formed

Trace element geochemistry of the Early to Late Cretaceous deposits of the Grajcarek thrust-sheets : a palaeoenvironmental approach (Małe Pieniny Mts., Pieniny Klippen Belt, Poland)

The chemical composition of the Cretaceous deposits of the Grajcarek thrust-sheets (Pieniny Klippen Belt, Poland) has been investigated to provide information on palaeoenvironment and provenance of pelagic and turbiditic particles. The material studied shows large variations in terrigenous and biogenic content. Phyllosilicates (mirrored in amounts of Al2O3, average 15 wt.%) and carbonates (6 wt.% of CaO) are common mineral components of the deposits excluding the Cenomanian radiolarian shales (CRS) that are enriched in silica (mean content of SiO2 is 64 wt.%). "Immobile" elements may be accommodated by phyllosilicates and accessory minerals (i.e. zircon, xenotime, apatite and Ti-oxides). Heavy minerals are significant within the Szlachtowa Fm. High field strength elements (HFSE) in the Malinowa Fm. are housed in secondary apatite and Fe-oxides. Lithophile trace elements (LILE) concentrations in the material studied are lower/comparable to Post-Archean Australian Shale (PAAS). Ba concentration in the CRS probably reflects enhanced bioproductivity. Interaction between major oxides, distributions of "immobile" and lithophile elements suggest that variation in trace elements through the succession was mainly controlled by the terrigenous input. The material studied was sourced from intermediate to felsic rocks of the Czorsztyn (Oravic) Ridge. The Szlachtowa Fm. and CRS are more mature than others due to low contents of clay minerals. The Szlachtowa Fm. also contains recycled material. The CRS correspond to the oceanic anoxic event 2 (OAE 2) whereas the "Black Flysch" of the Szlachtowa and Opaleniec formations may be related to the Early Cretaceous OAE

Provenance of Lower Cretaceous deposits of the western part of the Silesian Nappe in Poland (Outer Carpathians) : evidence from geochemistry

The turbiditic to hemipelagic, fine-grained deposits of the Hradiště Formation (Hauterivian, 132 Ma) to the Lhoty Formation (Albian-Cenomanian, 99 Ma) in the western part of the Silesian Nappe (Polish Outer Car- pathians) were studied mineralogically and geochemically to determine if the main factors controlling the che- mistry of the sedimentary material can be attributed to provenance, or to post-depositional processes. A high degree of weathering of the source rocks is indicated by the chemical index of alteration (CIA) that varies from 75.98 to 89.86, and Th/U ratios (~4 with outliers at 1.85 and >6). The co-occurrence of rounded and unabraded grains of zircon and rutile, the enrichment in Zr and Hf, as well as the high Zr/Sc ratios suggest that the Hradiště and Veřovice Formations contain recycled material. Plots of La/Th versus Hf and Th against Sc show that samples occur in the field of felsic and mixed felsic/basic sources. On a ternary La-Th-Sc diagram, all of the sediments studied are referable to the continental island-arc field. The European Plate, as an alimentary area, has a mosaic structure consisting of Cadomian and Variscan elements. The Proto-Silesian Ridge was detached from the conti- nent, because of rifting. Therefore, it could have corresponded to a continental island arc. The concentrations of Fe and trace metals (e.g., Mo, Au, Cu) in the Veřovice Formation and silica and potassium additions to the Veřovice and Lhoty Formations, as well as the fractionation of REE, and Nb, Ta, Zr, Hf, and Y can be explained by the action of basinal brines. The fluids were of hydrothermal origin and/or were released, owing to the dewatering of clay minerals. Diagenetic processes could have exerted a greater influence on sedimentary rock chemistry than the provenance and sedimentary processes. A distinction between primary, terrigenous elements and those changed diagenetically is necessary for the reliable determination of provenance

Provenance and diagenesis of siliciclastic and organic material in the Albian-Turonian sediments (Silesian Nappe, Lanckorona, Outer Carpathians, Poland) : preliminary studies

The provenance and diagenesis of the siliciclastic and hemipelagic sediments of three lithostratigraphic units: Lhoty Formation, Barnasiówka Radiolarian Shale Formation (BRSF) and Variegated Shales from Lancko- rona area, Polish Outer Carpathians, was approached by means of petrological and geochemical analysis of the representative samples. Data show that studied succession was mainly derived from two sources: 1. a dominant terrigenous fine-grained components have affinity with average upper continental crust (basing on mineral detritus, K2O/Rb ratio and Y/Ni vs. Cr/V ratios) and 2. biogenic siliceous material and macerals. Composition varies up section and accounts for changes in the detrital supply due to eustatic sea-evel changes. Organic petrology shows presence of organic detritus within the Lhoty Fm and dominance of marine-derived macerals in the BRSF. Chemical and petrological features imply a progressive deepening of the basin. The studied succession was diagenetically altered (e.g. coalification of bituminite, illitisation of smectite and pyritisation)

Source areas of the Grybów sub-basin : micropaleontological, mineralogical and geochemical provenance analysis (Outer Western Carpathians, Poland)

The Grybów Unit occurring in the Ropa tectonic window was the subject of micropaleontological and geochemical investigation. Studies, based on calcareous nannofossils, proved that the level of reworked microfossil is not higher than 22 % and it varies between two sections. Quantitative analyses of the reworked assemblages confirmed the domination of Cretaceous and Middle Eocene species. The Sub-Grybów Beds, Grybów Marl Formation and Krosno Beds were assigned to the Late Oligocene and represent the terminal flysch facies. Detrital material accumulated in the Oligocene sediments originated from the Marmarosh Massif, which is the eastern prolongation of the Fore-Magura Ridge. The microscopically obtained petrological features agree with the chemical composition of the samples. Mica flakes, rounded grains of glauconite, heavy mineral assemblage, including abraded grains of zircon, rutile and tourmaline as well as charred pieces of plant tissues are reworked components. Enrichment in zircon and rutile is confirmed geochemically by positive correlation between Zr and SiO_2. Zr addition is illustrated on 10 ×Al_2O_3-Zr-200 ×TiO_2 and Zr/Sc vs. Th/Sc diagrams. Interpretation of the A-CN-K diagram and variety of CIA and CPA values indicate that the source rocks were intensely weathered granite-type rocks

The genesis of the carbon dioxide in the Polish Outer Carpathians : Szczawa tectonic window case study : new insight

In the Polish sector of the Magura Nappe have long been known and exploited carbonate mineral waters, saturated with carbon dioxide, known as the "shchava (szczawa)". These waters occur mainly in the Krynica Subunit of the Magura Nappe, between the Dunajec and Poprad rivers, close to the Pieniny Klippen Belt (PKB). The origin of these waters is still not clear, this applies to both "volcanic" and "metamorphic" hypotheses. Bearing in mind the case found in the Szczawa tectonic window and our geological and geochemical studies we suggest that the origin of the carbon dioxide may be linked with the thermal/pressure alteration of organic matter of the Oligocene deposits from the Grybów Unit. These deposits, exposed in several tectonic windows of the Magura Nappe, are characterized by the presence of highly matured organic matter - the origin of the hydrocarbon accumulations. This is supported by the present-day state of organic geochemistry studies of the Carpathian oil and gas bed rocks. In our opinion origin of the carbon-dioxide was related to the southern, deep buried periphery of the Carpathian Oil and Gas Province. The present day distribution of the carbonated mineral water springs has been related to the post-orogenic uplift and erosion of the Outer (flysch) Carpathians

Maceral and calcareous nannofossil assemblages as proxies of late Rupelian (Oligocene) environmental changes in the Paratethys : an example from a section of the Menilite Formation in the northern Outer Carpathians

The Menilite Formation (Oligocene) of the Skole Nappe in the Polish Carpathians was deposited in the Paratethys. Deep-sea unbioturbated fine-grained carbonates of the Dynów Marl Member contain cold-water calcareous nannoplankton from Zone NP23 (Rupelian), including Reticulofenestra ornata and Pontosphaera fibula, which are typical of brackish waters in the Paratethys. It is likely that the water column was brackish in the upper part and fully marine and anoxic in the lower part. The Dynów Marl Member records the maximum isolation of the Paratethys from the oceanic circulation (the Upper Solenovian Event). The overlying green mudstones (probably the Krępak Member) are shallowly bioturbated. They contain fully marine, warm-water calcareous nannoplankton from Zone NP24. The environmental change (marine/brackish) is reflected in the quantity and type of organic matter. The abundance and preservation of organic matter are very high (TOC varies from 2.7 wt % to 26 wt %; HI values are >300 mg HC/g TOC) in brown, laminated shales, which were accumulated in saline anoxic conditions. The macerals in the shales are predominantly composed of the liptinite group, including lamalginite, telalginite, liptodetrinite, and bituminite. These macerals are primarily derived from planktonic and benthic algae as well as bacteria. The percentages of vitrinite and inertinite, originating from terrestrial sources, range up to 10% and 0.5%, respectively. The macerals are much less abundant in marls of the Dynów Marl Member because of dispersion in the carbonate groundmass during the calcareous nannoplankton blooms in brackish surface waters. The overall liptinite (mainly liptodetrinite and lamalginite) contribution is 77%–99.7%. Vitrinite and inertinite contents are in average 4.6% and 0.3%, respectively. Macerals are also infrequent in the overlying green mudstones, likely because of oxidation and consumption by organisms in warmer waters