Wyniki wyszukiwania - Biblioteka Nauki

1

Apparent sea-level change at times of extraordinary sediment supply: integrated facies analysis and chemostratigraphy of Early Toarcian Oceanic Anoxic Event, Peniche, Portugal

100%

Hesselbo S. , Jenkyns H. , Duarte L. , Veiga de Oliviera L.

|

tom Vol. 4, no. 1

171-172

EN

The Toarcian Oceanic Anoxic Event in the Early Jurassic was a time of major environmental change characterized by widespread deposition of organic-rich black shales in both deep- and shallow-marine settings. Facies evidence, mainly from the European area, has been used to argue for a major sea-level rise in concert with oceanic anoxia, extinction of certain groups, and perturbation of the carbon cycle. However, in a number of locations, such as in the Lusitanian Basin, Portugal, it has also been argued previously that the start of the event was characterized by sea-level fall rather than rise, as evidenced by the initiation of gravity-flow deposition. In this study we combine new marine and terrestrial carbon-isotope and lithological data to suggest an alternative model for development of facies patterns in this basin, whereby an abrupt increase in sediment flux from the hinterland led to slope instability and gravity-flow deposition that lasted as long as the carbon-cycle perturbation. This interpretation is supported by existing osmium and strontium isotope data, which have been interpreted to indicate a significant continental transient increase in continental weathering fluxes. In effect this event provides a good example from the rock record where the assumption of constant sediment supply is demonstrably false, but in which the facies patterns may still be predictable on a variety of scales.

2

Facies and carbon isotope studies in southern Tibet suggest that the Toarcian extinction was diachronous

100%

Hallam A.

|

tom Vol. 4, no. 1

168-168

EN

A record of the Toarcian (Early Jurassic) mass extinction is reported from eastern Tethyan (Tibetan) locations for the first time, using both nannopalaeontological and carbon isotope evidence. These show a similar succession of events to those seen in western Tethys and Boreal northern Europe but with a considerable delay in their timing. Thus, transgression and spread of oxygen-poor bottom waters is seen, but the onset of the dysaerobic deposition occurs late in the stage in Tibet whilst in western Tethyan and Boreal locations they develop near the base of the stage. The benthic extinctions were similarly delayed, with the result that the two principal victims of the crisis in the western Tethyan Realm, the lithiotid bivalves and the lituolid Foraminifera, persisted until high in the Toarcian in eastern Tethys. The Toarcian extinction event was therefore a protracted crisis associated with the diachronous onset of oxygen-poor deposition in marine settings.

3

Summer–winter contrast in carbon isotope and elemental composition of total suspended particulate matter in the urban atmosphere of Krakow, Southern Poland

88%

Zimnoch M. , Morawski F. , Kuc T. , Samek L. , Bartyzel J. , Gorczyca Z. , Skiba A. , Rozanski K.

|

2020

|

tom Vol. 65, No. 3

181--191

EN

The city of Krakow located in southern Poland ranks among the most polluted urban agglomerations in Europe. There are persisting controversies with respect to impact of different pollution sources operating in Krakow agglomeration on air quality within the city. The presented pilot study was aimed at exploring the possibilities offered by elemental and carbon isotope composition of total suspended particulate matter (TSPM) for better characterization of its sources in Krakow atmosphere. The analyses of carbon isotope composition of total carbon in the investigated TSPM samples were supplemented by parallel analyses of radiocarbon content in atmospheric carbon dioxide (CO2). This study revealed large seasonal variability of carbon isotope composition in the analysed TSPM samples. This large variability reflects seasonally varying contribution of different sources of fossil and modern carbon to the TSPM pool. The elemental composition of TSPM also reveals distinct seasonal variability of the analysed elements, reflecting varying mixture of natural and anthropogenic sources of those elements. A linear relationship between the fossil carbon load in the TSPM samples and the fossil carbon load in the atmospheric CO2 was found, pointing to the presence of additional source of anthropogenic carbonaceous particles not associated with burning of fossil fuels. Wearing of tyres and asphalt pavement is most probably the main source of such particles.

4

The Middle Oxfordian Platysphinctes event-horizon – an integrated tool in the correlations around the boundary of the Plicatilis and Transversarium zones in Europe

75%

Glowniak E. , Wierzbowski H.

|

tom Vol. 4, no. 1

162-163

EN

Palaeobiogeographic differentiation of the Late Jurassic faunas of the northern hemisphere was connected with temporal excursions and mixing of the Boreal-Subboreal and Mediterranean ammonites in the area of the Submediterranean epicratonic seas of the northern Tethyan shelf. These excursions are well recognized from the Late Oxfordian onwards (e.g. Atrops et al. 1993) but are less well-known in the Middle Oxfordian. However, the lower Mid-Oxfordian Platysphinctes event-horizon first recognized in central Poland (GĐowniak 2000), has been recently evidenced also in southern Poland and NW Germany. According to the new study (GĐowniak 2006b, in press) it appears in central Europe within the Arkelli Horizon of the Arkelli Subzone (Mid-Oxfordian Plicatilis Zone in the usage of the Submediterranean zonal scheme based on perisphinctid lineage, GĐowniak 2002, 2006a) and was a proxy for a biogeographical phenomenon referred to as the “Mediterranean Spread”. At that time, geographical barriers did not hinder communication between the Submediterranean and Tethys basins, which may point to the occurrence of the “Mediterranean Spread” in conditions of a sea-level rise. In accordance with the previous opinion remain geochemical isotope data based on stratigraphically well-dated belemnite rostra derived from the Mid-Oxfordian sections of central Poland (Wierzbowski 2002). A gradual positive shift in ä13C values, which starts at the Lower/Middle Oxfordian boundary, reaches its maximum in the Platysphinctes event-horizon. According to Wierzbowski (2002) the early Middle Oxfordian carbon isotope excursion may have been linked to transgression, which occurred during a longer period of the crisis in oceanic carbonate sedimentation. The early Middle Oxfordian positive carbon isotope shift was subsequently recognized in the sections of Scotland (Wierzbowski 2004, Pearce et al. 2005). The geochemical events from Poland and Scotland are simultaneous and should be correlated with the Platysphinctes event-horizon (cf. Wierzbowski 2002, 2004). As a consequence, the latter becomes a precise marker for the stratigraphic correlations of the Mid-Oxfordian zonal schemes in the upper Plicatilis Zone between the Submediterranean and Boreal-Subboreal Europe.

5

Sedimentary development and isotope analysis of deposits at the Cretaceous/Palaeogene transition in the Paraíba Basin, NE Brazil

75%

Neumann V. H. , Barbosa J. A. , Nascimento-Silva V. M. , Sial A. N. , Filho M.

Geologos

|

2009

|

tom Vol. 15, No. 2

103--113

EN

New data are presented for three formations (Itamaracá, Gramame and Maria Farinha) and two boundaries (Campanian/Maastrichtian and Maastrichtian/Danian) in the Olinda Sub-basin of the Paraíba Basin. Currently accepted facies models, sequence stratigraphy characterizations, and stable-isotope data of carbon and oxygen are reviewed. The carbonate cement of the Itamaracá Formation sandstones shows carbon- and oxygen-isotope ratios consistent with a shallow-marine depositional environment: δ18O ranges from -0.8 to -2.7‰ PDB, and δ13C ranges from +1 to +2‰ PDB. Within the Itamaracá Formation, a maximum flooding surface at the Campanian/Maastrichtian transition has been identified. During the Maastrichtian, a Highstand System Tract was deposited, which shows an increase in temperature and marine bioproductivity as recorded by stable-isotope values (δ18O from -3 to -5‰ PDB, and δ13C values of -1.2, -0.3, 0.1 and +2.3‰ PDB). Just below the K/Pg boundary, the O-isotope signal indicates three warming phases, alternating with four cooling phases.

6

Foraminiferal colonization related to the Zechstein (Lopingian) transgression in the western part of the Wolsztyn Palaeo-Ridge area, Western Poland

75%

Peryt D. , Peryt T. M. , Raczyński P. , Chłódek K.

|

2012

|

tom Vol. 56, No 3

529--546

EN

The basal Zechstein succession in SW Poland is dominated by breccias and/or conglomerates or extraclast-bearing bioclastic limestones, which were deposited during rapid flooding of the pre-existing intracontinental basin in the early Lopingian (Late Permian). Of these, the boulder-cobble breccias and conglomerates are interpreted as deposited in a rocky shore-zone where density flows and upwelling prevailed. The breccias gradually pass up into bryozoan (or other bioclastics) grainstones. The matrix-supported breccias were deposited as large extraclasts and blocks of Carboniferous rock were rolled down or detached from a cliff and were then either embedded into a carbonate sand or formed a framework supplying voids that could be colonized by tubular encrusting foraminifers. These foraminifers abound in all basal Zechstein facies (except in the debris-flow deposits) and are attributed to Palaeonubecularia. The associated faunas include other foraminifers (uniserial and hemigordiopsids), bryozoans, brachiopods, bivalves, gastropods, and microbial deposits. The prolific growth of tubular encrusting foraminifers has resulted from nutrient supply from the basin by upwelling. Botryoidal aragonite cements (also interpreted as due to upwelling) also characterize the basal Zechstein strata, although they were previously reported only from the upper Zechstein Limestone. The ẟI3C values of the basal Zechstein deposits show small variation and oscillated around 4.0%o, suggesting that these deposits are younger than the Kupferschiefer.

7

Foraminifers and stable isotope record of the Dubivtsi chalk (upper Turonian, Western Ukraine): palaeoenvironmental implications

75%

Dubicka Z. , Peryt D.

|

2012

|

tom Vol. 56, No 1

199-214

EN

A combined micropalaeontological and stable isotope study of the Dubivtsi chalk in the Western Ukraine indicates its middle late Turonian age. One long-term and clearly distinguishable positive excursion of the isotope curve (d1318

8

Origin of siderites from the Lower Jurassic Ciechocinek Formation from SW Poland

75%

Leonowicz P.

|

2007

|

tom Vol. 51, No 1

67-78

EN

Sideritic rocks, which are characteristic constituents of muddy-silty deposits of the Lower Jurassic Ciechocinek Formation, occur commonly as layers, lenses and small irregular concretions composed of siderite mudstone and siltstone as well as less common lenses of sideritic sandstones. Three types of siderite cement were observed in thin sections: fine-crystalline variety (SF), coarse-crystalline rhombohedra (SR) and fine-crystalline biogenic aggre gates (SA). In all these types BSE analysis revealed compositional zonation of crystals, with in ternal parts enriched in Mg, Mn and Ca and outer zones almost pure siderite. d13C values and chemical composition of siderites combined with the presence of early diagenetic pyrite indicate that siderite crystallized from brackish marine-derived solutions; only in the case of two samples from the lower part of the Ciechocinek Formation the fresh water origin cannotbe excluded. Mn and Fe were supplied by rivers and released by Fe- and Mn-reduction in suboxic zone, whereas Mg and Ca were derived from sea water, which infiltrated into the sediment. Crystal zonation resulted from the diagenetic evolution of pore water as the sediment was buried. Similar composition and development of siderite crystals from different parts of one layer indicate that siderite precipitated simultaneously throughout the whole horizon. Precipitation began from the formation of numerous nuclei and continued by growth of crystals onto them. It could begin already in the iron reduction subzone and continued in the sulphate reduction and methanogenesis zones.

9

Zawartość i skład izotopowy węgla organicznego z utworów formacji poznańskiej (miocen–pliocen) z rejonu Konina (środkowa Polska : sugestie paleośrodowiskowe i stratygraficzne

51%

Gąsiewicz A.

Przegląd Geologiczny

|

2004

|

tom Vol. 52, nr 6

519-–526

EN

The paper presents interpretation of total organic carbon (TOC) content and carbon isotopic composition of organic matter within the Miocene/Pliocene Poznań Formation deposits recorded in BK 110 borehole in the Konin area (Central Poland). The TOC content as well as a :13C(TOC) PDB values vary widely throughout the deposits, from 0.1% to 6.1% (0.6% at average) and from –14.2‰ to –26.2‰ (–23.2‰ at average), respectively. The distribution of these parameters within the series allow to distinguish the lower part, which is thinner and enriched in organic matter accumulation, and the upper part, which is thicker and clastic. The a:13CTOC values indicate that C3 plant material prevailed in the lower part, while the upper part contains of C3+C4 plant material or C3 + marine organic matter. The subdivision of the Formation into lower and upper parts reflects a shift from peat-bog vegetation in nearshore lake into brackish lagoon environment with a periodical supply of terrigenous land material. The shift in the origin of the organic matter and sedimentological features of the Poznań Formation sediments imply a tectonic event or/and climatic shift, possibly connected with evolution of plants population and thus relative decrease in C3 and increase in C4 organic material at the Miocene– Pliocene boundary.

10

An integrated study (inoceramid bivalves, ammonites, calcareous nannofossils, planktonic foraminifera, stable carbon isotopes) of the Ten Mile Creek section, Lancaster, Dallas County, north Texas, a candidate Global boundary Stratotype Section and Point

51%

Gale A.

|

tom Vol. 57, no. 2

113-160

EN

The WalMart section on Ten Mile Creek, Lancaster, Dallas County, Texas, exposes a 23 metre section of Austin Chalk that can be integrated into a more than 60 m composite sequence for the Dallas area on the basis of bed-by-bed correlation. The section was proposed as a possible candidat e Global Boundary Stratotype at the 1995 Brussels meeting on Cretaceous Stage boundaries, with the first occurrence of the inoceramid bivalve Cladoceramus undulatoplicatus (ROEMER, 1852) as the potential boundary marker. An integrated study of the inoceramid bivalves, ammonites, planktonic foraminifera, and calcareous nannofossils places the first occurrence of Cl. undulatoplicatus in a matrix of ten ancillary biostratigraphic markers. The candidate Global boundary Stratotype Section and Point (GSSP) is located within a composite stable carbon isotope curve for the Austin Chalk as a whole. This shows it to lie 3.5 m below the Michel Dean stable carbon isotope event, originally recognised in the English Chalk. The first occurrence of Cl. undulatoplicatus lies in the same position in relation to stable carbon isotope events in both Texas and England that can in principle be recognised globally in marine sediments. The WalMart section satisfies many of the criteria required of a GSSP for the base of the Santonian Stage, although ownership and access require clarification.