Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 6
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The lower Upper Albian ammonite genus Dipoloceras Hyatt, 1900 (subfamily Mojsisovicsiinae Hyatt, 1903) is represented in KwaZulu-Natal by the type species, D. cristatum (Brongniart, 1822), marker species for the base of the Upper Albian Substage. Rhytidoceras van Hoepen, 1931 (of which Drepanoceras van Hoepen, 1931, non Stein 1878 and Ricnoceras van Hoepen, 1941, are synonyms), previously regarded as subgenera of Dipoloceras, are afforded generic status as are its supposed synonyms Diplasioceras van Hoepen, 1946a, and Euspectroceras van Hoepen, 1946a. The type species of these genera are revised, and assigned to the subfamily Pervinquierinae Spath, 1926.
Go to article

Authors and Affiliations

William James Kennedy
1
Herbert Christian Klinger
2

  1. Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK and Department of Earth Sciences, South Parks Road, Oxford OX1 3AN, UK
  2. Natural History Collections Department, Iziko South African Museum, P.O. Box 61, Cape Town, 8000 South Africa
Download PDF Download RIS Download Bibtex

Abstract

The cosmopolitan Late Albian ammonite subgenus Pervinquieria ( Deiradoceras) van Hoepen, 1931, and its synonyms Cechenoceras van Hoepen, 1941 and Mimeloceras van Hoepen, 1944, originally based on material from northern KwaZulu-Natal, are reviewed. The type material of the type species, Subschloenbachia prerostrata Spath, 1921, is revised and reillustrated, as are its numerous synonyms.
Go to article

Authors and Affiliations

William James Kennedy
1
Herbert Christian Klinger
2

  1. Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK and Department of Earth Sciences, South Parks Road, Oxford OX1 3AN, UK
  2. Natural History Collections Department, Iziko South African Museum, P.O. Box 61, Cape Town, 8000 South Africa
Download PDF Download RIS Download Bibtex

Abstract

In this contribution we complete the revision of species we refer to Pervinquieria ( Deiradoceras) van Hoepen, 1931, focusing on those assigned by him to his genera Cechenoceras and Mimeloceras.
Go to article

Authors and Affiliations

William James Kennedy
1
Herbert Christian Klinger
2

  1. Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK and Department of Earth Sciences, South Parks Road, Oxford OX1 3AN, UK
  2. Natural History Collections Department, Iziko South African Museum, P.O. Box 61, Cape Town, 8000 South Africa
Download PDF Download RIS Download Bibtex

Abstract

Ball-shaped concretions ("cannon balls") commonly occur in a marine, organic carbon-rich sedimentary sequence (Innkjegla Member) of the Carolinefjellet Formation (AptianAlbian) in Spitsbergen. The sedimentologic, petrographic and geochemical investigation of these concretions in the Kapp Morton section at Van Mijenfjorden gives insight into their origin and diagenetic evolution. The concretion bodies commenced to form in subsurface environment in the upper part of the sulphate reduction (SR) diagenetic zone. They resulted from pervasive cementation of uncompacted sediment enriched in framboidal pyrite by non-ferroan (up to 2 mol% FeCO3) calcite microspar at local sites of enhanced decomposition of organic matter. Bacterial oxidation of organic matter provided most of carbon dioxide necessary for concretionary calcite precipitation (δ13CCaCO3 ≈ -21%VPDB). Perfect ball-like shapes of the concretions originated at this stage, reflecting isotropic permeability of uncompacted sediment. The concretion bodies cracked under continuous burial as a result of amplification of stress around concretions in a more plastic sediment. The crack systems were filled by non-ferroan (up to 5 mol% FeCO3) calcite spar and blocky pyrite in deeper parts of the SR-zone. This cementation was associated with impregnation of parts of the concretion bodies with microgranular pyrite. Bacterial oxidation of organic matter was still the major source of carbon dioxide for crack-filling calcite precipitation (δ13CCaCO3 ≈ -19% VPDB). At this stage, the cannon-ball concretions attained their final shape and texture. Subsequent stages of concretion evolution involved burial cementation of rudimentary pore space with carbonate minerals (dolomite/ankerite, siderite, calcite) under increased temperature (δ18OCa,Mg,FeCO3 ≈-14% VPDB). Carbon dioxide for mineral precipitation was derived from thermal degradation of organic matter and from dissolution of skeletal carbonates (δ13CCa,Mg,FeCO3≈ - 8‰ VPDB). Kaolinite cement precipitated as the last diagenetic mineral, most probably during post−Early Cretaceous uplift of the sequence.

Go to article

Authors and Affiliations

Krzysztof P. Krajewski
Bartłomiej Luks
Download PDF Download RIS Download Bibtex

Abstract

The aim of the presented work was an attempt to verify the geothermal conditions in the Polish Lowlands (Lower Jurassic and Lower Cretaceous reservoir) based on new geological information. The paper presents geothermal conditions in the Polish Lowlands according to the state of recognition at the end of 2022 in order to update the hydrogeothermal conditions in selected regions. Based on the scientific and research works published so far as well as numerous geothermal investments, and geological information from twenty-three new exploratory drilling events performed in the years 2000–2022 (nineteen of which were performed/documented after 2006), the authors undertook to update forecasts of the top surface of Lower Jurassic and Lower Cretaceous formations, the total thickness of these formations and the potential discharge of wells. The analysis was performed using the QGIS Desktop 3.24.1 software, a cross-platform and free open-source geoinformation software application (GIS ) that enables the viewing, editing and analyzing of spatial data and the creation of maps. The correction covered the course of the isolines on all six analyzed maps. The presented analysis made it possible to make a spot correction of the forecasted course of the isoline in relation to the maps published earlier in the Atlas of geothermal resources in the Polish Lowlands. Mesozoic formations developed in 2006, edited by Wojciech Górecki. Information obtained from newly drilled geothermal boreholes enabled the local correction of the forecasted values of individual parameters while maintaining the general trend.
Go to article

Authors and Affiliations

Wiesław Bujakowski
1
ORCID: ORCID
Piotr Zacharski
2
Bogusław Bielec
1
ORCID: ORCID
Magdalena Tyszer
1
ORCID: ORCID
Karol Pierzchała
1
Barbara Tomaszewska
3 1
ORCID: ORCID
Leszek Pająk
3 1
ORCID: ORCID
Beata Kępińska
1
ORCID: ORCID
Krystian Szczepański
2

  1. Mineral and Energy Economy Research Institute, Polish Academy of Sciences, Kraków, Poland
  2. Institute of Environmental Protection – National Research Institute, Warszawa, Poland
  3. AGH University of Science and Technology, Kraków, Poland
Download PDF Download RIS Download Bibtex

Abstract

The potential of heavy minerals as a provenance tracer in Albian arenites of extra-Carpathian Poland was assessed. Studies in this area have focused on various methods based on heavy mineral chemistry that provide an effective tool for reconstructing the provenance of quartz-rich sediments. The previously suggested division of the study area into two domains with different source areas: the western domain – the Miechów area, and the eastern domain – the Lublin area, was based on geochronological (monazite and muscovite dating) and rutile mineral chemical studies. The mineral chemistry of newly examined heavy minerals supports the previously suggested division. The mineral chemistry of detrital tourmaline suggests medium-grade metamorphic rocks as the main source in both domains. Detrital garnet in the western domain shows affiliation to the Góry Sowie Massif, while garnet in the eastern domain was most probably sourced from southern/central Norway. The western domain was most probably fed from rocks of the Bohemian Massif. The main source area for the eastern domain was most probably located in the Baltic Shield. The distinct division of the study area into two domains was caused by the palaeogeography of the region in the Albian and the action of longshore currents in south-eastward and eastward directions.

Supplementary Material 1
Supplementary Online Material 2






Go to article

Authors and Affiliations

Jakub Kotowski
1
Danuta Olszewska-Nejbert
1
Krzysztof Nejbert
1

  1. University of Warsaw, Faculty of Geology, Żwirki i Wigury 93, 02-089 Warszawa, Poland

This page uses 'cookies'. Learn more