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1

Provenance of quartz debris in the Central Western Carpathians at the end of the Triassic, as indicated by cathodoluminescence colours

Vďačný Marek, Michalík Josef

Acta Geologica Polonica

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2023

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Vol. 73, no. 1

103--114

EN

Lithic fragments including quartz grains occur infrequently in the shallow-marine limestone sequence of the Fatra Formation deposited in the tensional intra-shelf depression of the Central Western Carpathians during the Rhaetian. Nevertheless, their study can bring data answering questions of sources, palaeogeodynamic arrangement, and processes at the end of the Triassic. In this study, we examined optically the cathodoluminescence (CL) colours of single quartz grains from the Kardolína section (Tatra Mts, Slovakia). These colours reveal a dominance of grains derived from regionally metamorphosed and plutonic rocks. Grains of hydrothermal and pegmatite origin are less frequent. Some of the quartz grains show recycled cement rims suggesting at least a second cycle origin. This sedimentary basin was situated near to the passive margin formed by the Variscan consolidated terrains of the Vindelician Highlands. Our study of the CL colours of quartz grains contributes to the elucidation of the nature of the rocks of the vanished Vindelician mountain belt.

2

Detrital zircon analysis of metasedimentary rocks of the Staré Město Belt, Sudetes : implications for the provenance and evolution of the eastern margin of the Saxothuringian terrane, NE Bohemian Massif

Śliwiński Marek, Jastrzębski Mirosław, Sláma Jiří

Geological Quarterly

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2022

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Vol. 66, No. 2

art. no. 21

EN

The Staré Město Belt (SMB) in the Central Sudetes forms a Variscan tectonic boundary zone that is located between the Saxothuringian and Brunovistulian terranes of the Bohemian Massif. The three thrust-bounded upper, middle and lower lithotectonic units of the SMB are composed of metasedimentary and Late Cambrian metavolcanic rocks. A new LA-ICP-MS zircon geochronology supported by zircon typology studies of the mica schists of the upper unit and the migmatitic paragneisses of the middle unit provides new insights into the provenance and evolution of the SMB. Our new data were obtained from metasedimentary rocks and compared to the previously published zircon ages of the SMB metavolcanic rocks. The results indicate that the metasedimentary and bimodal metavolcanic rocks in the separate lithotectonic units of the SMB originally formed Late Cambrian volcano-sedimentary successions. The source areas of the sedimentary basins studied were dominated by Neoproterozoic and Paleoproterozoic crystalline rocks that were presumably located near the West African Craton of Gondwana. A comparison of the detrital age spectra obtained with those previously published from the region indicates a strong association of the entire SMB with the Saxothuringian terrane of the Bohemian Massif. During partial melting of the metasedimentary rocks of the middle unit of the SMB, Cambrian and older zircon grains were affected by solid-state transformations that caused partial resetting of the U-Pb dates, changes in internal zircon textures and reductions in Th/U ratios.

3

Wood density in European larch (Larix decidua Mill.) from selected provenances grown at the Siemianice Forest Experimental Station

Szaban Jarosław, Kowalkowski Wojciech, Łacka Agnieszka, Karaszewski Zbigniew

Drewno : prace naukowe, doniesienia, komunikaty

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2021

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vol. 64, nr 207

27--41

EN

The purpose of this study was to determine variation in the density of wood from different provenances, growing under the same soil and climate conditions. Samples were obtained from an experimental site located at the Siemianice Forest Experimental Station. We analyzed larch wood samples from trees aged 48 years, collected from six different provenances in Poland. Diameter at breast height (DBH) and tree height were used to calculate the parameters for sample trees, from which a 70 cm segment was cut, from breast height upwards (up to 2 m of tree height). Samples with dimensions 20 × 20 × 30 mm were obtained from the material. Sample volume was determined by stereometry. Relative density was determined for 890 samples. The highest wood density was found in trees from Czerniejewo, and the lowest in trees from Rawa Mazowiecka. Analysis of variance, including the mean wood density values of trees, did not demonstrate significant differences between provenances in terms of this characteristic. Mean relative density was higher in larch wood samples from the heartwood zone. The density of samples cut closer to the bark was lower, as the value was affected by the large content of sapwood. A relation was found between the provenances from which the study material was sourced and the relative density of wood.

4

Detrital zircon age data from the conglomerates in the Upper Silesian and Małopolska blocks, and their implications for the pre-Variscan tectonic evolution (S Poland)

Habryn Ryszard, Krzemińska Ewa, Krzemiński Leszek, Markowiak Marek, Zieliński Grzegorz

Geological Quarterly

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2020

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Vol. 64, No. 2

321--341

EN

Detrital zircon age of the conglomerates from the Upper Silesian (USB) and Małopolska (MB) (S Poland) have been investigated to compare their deposition age and possible provenience. The size and poor sorting of the lithoclasts reflect a short transportation, with deposition close to the sourceland. The Late Ediacaran conglomerate of the Potrójna IG 1 and Raciechowice 1 boreholes (USB) reveal a good match between the ages known from the local basement explored by boreholes. Detrital zircon clusters in a range of 579-585 Ma and 628-638 Ma and of 707 Ma are consistent with the distributions of Cadomian magmatism within the nearest orogenic belt or those identified elsewhere within the Brunovistulicum. In case of the conglomerate deposited in the Batowice 2 borehole (MB), the zircon clusters of 532, 551, 594 and 649 Ma, accompanied with a pre-Svecofennian group peaked at 2071 Ma, and the lack of Sveconorvegian population may document a tectono-sedimentary interaction between the Baltica's southern margin and the Gondwanan Cadomian and Late Cadomian basement during Early Paleozoic time. This conglomerate bed was deposited later, after the Early Ordovician, then docking of Małopolska Block - Baltica was probably completed.

5

What Support do Systematic Reviews Provide for Evidence-informed Teaching about Software Engineering Practice?

Budgen David, Brereton Pearl, Williams Nikki, Drummond Sarah

e-Informatica Software Engineering Journal

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2020

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Vol. 14, nr 1

7--60

EN

Background: The adoption of the evidence-based research paradigm by software engineering researchers has created a growing knowledge base provided by the outcomes from systematic reviews. Aim: We set out to identify and catalogue a sample of the knowledge provided by systematic reviews, to determine what support they can provide for an evidence-informed approach to teaching about software engineering practice. Method: We undertook a tertiary study (a mapping study of systematic reviews) covering the period to the end of 2015. We identified and catalogued those reviews that had findings or made recommendations that were considered relevant to teaching about industry practice. Results: We examined a sample of 276 systematic reviews, selecting 49 for which we could clearly identify practice-oriented findings and recommendations that were supported by the data analysis provided in the review. We have classified these against established software engineering education knowledge categories and discuss the extent and forms of knowledge provided for each category. Conclusion: While systematic reviews can provide knowledge that can inform teaching about practice, relatively few systematic reviews present the outcomes in a form suitable for this purpose. Using a suitable format for presenting a summary of outcomes could improve this. Additionally, the increasing number of published systematic reviews suggests that there is a need for greater coordination regarding the cataloguing of their findings and recommendations.

6

Charakterystyka i proweniencja piaskowców z gotyckiego portalu bazyliki św. Elżbiety Węgierskiej we Wrocławiu

Zboińska Katarzyna, Bartz Wojciech

Przegląd Geologiczny

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2019

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Vol. 67, nr 9

749--757

EN

The St. Elizabeth of Hungary Basilica is one of the most important and recognizable monuments of Wroclaw - the capital of Lower Silesia (SWpart of Poland). The origin of the church dates back to the beginning of the 13th century. The basilica received its present Gothic form in the 14th-15th centuries. At the foot of the church tower, overlooking the buildings of the nearby Market Square, there is a late-Gothic portal built in 1456. This is the oldest portal of the basilica. Adjacent to it, there are epitaphs of wealthy Wroclaw burghers. These monuments are the top-class works of Silesian stonemasonry and also an interesting example of the use of natural stone in constructing architectural details. From the portal and three epitaphs (devoted to the Krapps’family, Georg Althoff Scholz and Hans Schulz von Wolkovitz), atotal often samples of clastic rock were collected. These were subjected to detailed petrographic and mineralogical studies in order to determine the provenance of the stone material. The research confirmed that these architectural details were made of quartz sandstones. The probable source of this material was the Cretaceous joint sandstones from the North-Sudetic Basin (Conacian, upper joint sandstone - Rakowice type).

7

New interpretation of the provenance of crystalline material from Oligocene flysch deposits of the Skole Nappe, Poland: evidence from heavy minerals and clasts in the Nowy Borek section

Salata Dorota, Uchman Alfred

Geologos

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2019

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Vol. 25, No. 2

163--174

EN

The Futoma Member (Oligocene, Rupelian) of the Menilite Formation is present only in the northern part of the Skole Nappe. Some diatomitic layers of this member in the Nowy Borek section contain coarse-grained detrital material composed of a variety of metamorphic, volcanic and sedimentary rock fragments. The material derives from primary and secondary sources. Most abundant are debris of metamorphic rocks, mostly gneisses and mica schists. The metamorphic origin of these rocks is confirmed by the composition of heavy mineral assemblages and garnet chemistry. These rocks could have been transported from a local source located close to the margin of the Skole Basin or within that basin. The volcanic rocks reflect Paleogene volcanic activity that was widespread in the Carpathian region. Cherts, which could have been subjected to synsedimentary erosion, may have been derived from the older portions of the same formation.

8

Geochemistry of shales of the Qadir Member (Nayband Formation, Upper Triassic), East Central Iran (Tabas Block) : implications for provenance and palaeogeography

Zamaniyan Ehsan, Khanehbad Mohammad, Moussavi-Harami Reza, Mahboubi Asadollah

Geological Quarterly

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2019

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Vol. 63, No. 3

603--618

EN

The Upper Triassic shale of the Qadir Member of the Nayband Formation, East Central Iran has been analysed geochemically to evaluate provenance and palaeogeography. The Qadir Member in the Parvadeh Coal Mine section is 450 metres thick, and includes sandstone, shale, coal, siltstone, and fossiliferous limestone. XRD analysis of shale samples from the Qadir Member largely indicated the presence of illite and chlorite, with small amounts of kaolinite and montmorillonite. On binary and triangular diagrams the data suggests an intermediate igneous source rock for these shales. Plotting the geochemical data on binary diagrams also indicates the tectonic setting of an active continental margin, perhaps reflecting the Early Cimmerian tectonic event with Neothetys subduction under the Iran Plate, and collision of the Iran Plate with Turan during the Late Triassic. The Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values for shale from the Qadir Member of Nayband Formation vary from 74.04 to 80.54 (average 78.02) and 84.31 to 91.85 (average 87.81), respectively, indicating moderate to high chemical alteration in the source area and suggesting a semi-humid climate during deposition. The geochemical data and palaeogeographical models indicate that the Qadir Member shale was deposited on an active margin in a shoreline to transitional-marine setting.

9

Relationship between the abrasion of tektite clasts and their host sedimentary facies, Pleistocene, SW Poland

Brachaniec Tomasz

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 1

83--90

EN

This study reports on the occurrence of tektite clasts with a markedly different degree of abrasion in two different fluvial facies of the Pleistocene deposits of the Nysa Kłodzka river near Paczków, SW Poland. The question addressed by the study is whether the redeposited and differently abraded tektite glass clasts derive from different distances/sources, or whether their differing degree of abrasion relates to their different host sediment as the medium of river bedload transport. Laboratory tumbling experiments are used to estimate the progress of tektite abrasion with the distance travelled within a bedload sediment of the corresponding grain-size composition. The study concludes that there is a direct relationship between the abrasion degree of tektites and their host sediment facies, but it is not simple and straight forward, as a range of specific factors comes potentially into play. Their role is discussed and is recommended to be taken into account in an abrasion experiment design and in the interpretation of experimental results. The study suggests that the tektite clasts found near Paczków were transported over a distance of about 2-4 km and were derived from denudation of the nearby Bardzkie Mts.

10

Geochemistry of siliciclastic rocks from the Shemshak Group (Upper Triassic-Middle Jurassic), northeastern Alborz, northern Iran : implications for palaeoweathering, provenance, and tectonic setting

Taheri A., Jafarzadeh M., Armstrong-Altrin J. S., Mirbagheri S. R.

Geological Quarterly

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2018

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Vol. 62, No. 3

522--535

EN

Combined petrographic and geochemical data of the siliciclastic sedimentary rocks from the Shemshak Group in the northeastern Alborz Mountains, north of Iran are described, together with their implications for palaeoweathering, their provenance, and tectonic setting. Based on field observations and modal composition, the sandstones are classified as litharenites. The chemical index of alteration (CIA) indicated that the source terrains underwent a moderate intensity of chemical weathering. The index of chemical variation (ICV) values indicated that the Shemshak Group rocks were immature and related to a source area with an active tectonic regime. Major, trace and rare earth element (REE) data suggested the domination of mixed sedimentary (recycled) and igneous rocks in the source area of the Shemshak Group. Petrographic and geochemical characteristics of Shemshak Group rocks suggest an active continental margin (ACM), which corresponds to the collision of the Iran plate with the Turan plate.

11

Wstępna charakterystyka pierwiastków ziem rzadkich i innych pierwiastków śladowych w osadach drobnoziarnistych z pogranicza triasu i jury w dawnej bruździe śródpolskiej

Brański P.

Biuletyn Państwowego Instytutu Geologicznego

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2018

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nr 472

255--270

PL

Skały drobnoklastyczne z pogranicza triasu i jury (retyk–hetang), nagromadzone w dawnej bruździe śródpolskiej były przedmiotem badań geochemicznych w Państwowym Instytucie Geologicznym – Państwowym Instytucie Badawczym w Warszawie. 94 próbki iłowców i mułowców, pochodzące z sześciu archiwalnych rdzeni wiertniczych, przeanalizowano metodami ICP-MS i XRF, na zawartość pierwiastków ziem rzadkich (REE) i innych pierwiastków śladowych. Wyniki wskazują, że źródłem większości badanych mułowców i iłowców były skały osadowe górnej skorupy kontynentalnej starych obszarów kratonicznych, których protolit miał charakter umiarkowanie felzytowy. Procesy wietrzenia i recyklingu zmodyfikowały, do pewnego stopnia, pierwotny skład chemiczny. Jednak w retyku i wczesnym hetangu, w południowo-wschodnim segmencie bruzdy, niektóre dane geochemiczne sugerują większą dostawę z wulkanicznego protolitu o charakterze maficznym. Ponadto, w kilku próbkach zaobserwowano wyraźne wzbogacenie w pierwiastki ziem rzadkich, w wyniku domieszki minerałów akcesorycznych, będących głównymi nośnikami REE. Tym niemniej, na podstawie obecnie otrzymanych wyników, koncentracje REE (i innych pierwiastków śladowych) w bruździe śródpolskiej są niskie i mają one naukowe znaczenie wskaźnikowe, natomiast nie mają znaczenia surowcowego.

EN

Fine-grained siliciclastic rocks from the Triassic-Jurassic transition (Rhaetian–Hettangian) in the former Mid-Polish Trough were the subject of the geochemical study at the Polish Geological Institute – National Research Institute in Warsaw. Ninety-four samples of claystones and mudstones from six archived drill cores were analysed by ICP-MS and XRF for rare earth elements (REE) and other trace elements. The results indicate that the sources of most of the claystones and mudstones were sedimentary rocks of the upper continental crust of old cratonic areas, where the protolith had a moderately felsic character. Weathering and recycling processes modified the original chemical composition to some extent. However, during Rhaetian and early Hettangian, some geochemical data in the south-eastern segment of the MPT suggest significant input from a mafic volcanic protolith. Moreover, a clear enrichment in rare-earth elements was observed in few samples, caused by admixtures of accessory minerals (being a main carrier of REE). Nevertheless, based on currently obtained data, the Rhaetian–Hettangian concentrations of REE (and other trace elements) in the MPT are low and they are of scientific indicative significance, not of raw material importance.

12

New data on the continental deposits from the Cao Bang Basin (Cao Bang-Tien Yen Fault Zone, NE Vietnam) - biostratigraphy, provenance and faciespattern

Wysocka A., Pha D. P., Durska E., Czarniecka U., Thang D. V., Filipek A., Cuong N. Q., Tuan D. M., Huyen N. X., Tha H.V.

Acta Geologica Polonica

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2018

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Vol. 68, no. 4

689--709

EN

The Cao Bang Basin is the northernmost of the basins related to the Cao Bang-Tien Yen Fault Zone in northern Vietnam. The basin is filled with a thick series of continental deposits. However, the exact age of the sedimentary basin infill has been under discussion for a long time. Because of new published data, the authors have decided to revisit this basin. Palynological data has allowed us to assign the Cao Bang Basin infill to the Lower Oligocene PC1 complex of the Shangcun Fm. (southern China). Among the saccate grains of gymnosperms, the domination of Cathaya and Pinus was observed, whereas angiosperms are represented by Carya, Celtis, Hammamelidaceae, Ulmus and also Pterocarya, Quercus, the Castanea–Castanopsis–Lithocarpus group, and the Loranthaceae. Among pteridophytes occur Laevigatosporites, Osmundaceae, and Pteris. The sedimentological features of the Cao Bang Basin are distinct from those of other basins from the Cao Bang-Tien Yen Fault Zone. The basin is filled with a wide variety of clastic deposits, from some of coarse-grained, alluvial-fan origin, through sandy beds of fluvial origin up to fine, organic-rich lacustrine deposits. The coarse-grained lithofacies are built of clasts derived mainly from local sources. The sandstones from the basin equally are submature or immature. They contain a lot of lithoclasts, the composition of which depends on the sample location within the basin. The potential source area is composed of older sedimentary units and of granitic rocks. The geochemical samples studied reflect the geochemical composition of silicic source rocks with only a minor contribution of basic components. The succession that fills the basin is interpreted as a typical fill for relatively long-lasting evolving half-graben or strike-slip basins. Moreover, the basin is partly occupied by a subsequent present-day sedimentary basin of Quaternary age.

13

The geochemical composition of sediment as a proxy of provenance and weathering intensity: a case study of Southwest Nigeria’s Coastal Creeks

Phillips O. A., Falana A. O., Adebayo A. J.

Geology, Geophysics and Environment

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2017

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Vol. 43, no. 3

229--248

EN

The study of the geochemical composition of sediments was undertaken to evaluate the degree of weathering and appraise the relative proportion of mafic and felsic rock materials being transported from source to sink. Thirty-three surface sediment samples collected from the creeks were used for particle size and chemical analyses. An inductively coupled plasma-Mass Spectrometer was used to determine the elemental composition of the sediments. The clay dominated Yewa and western Badagry creeks gave evidence of higher average concentrations of Ni, Sr, Y, Nb, Sc, Co, V, and Th than the eastern end of segment of Badagry Creek. The data generated from elemental ratios such as Al 2 O 3 /TiO 2, TiO 2 /Zr and binary plots of Th/Sc-Cr/Sc, Th-Sc, Y/Ni-Cr/V, TiO 2 -Zr and ICV-CIA (index of compositional variability against chemical index of alteration) showed that source sediments are composed of upper and lower crustal compositions. Also, the creeks were marked by their variation in terms of the proportion of felsic and mafic components. For instance, Yewa and western Badagry creeks are more enriched in mafic constituents, whereas the enrichment of felsic materials is significant at the eastern end of Badagry Creek. Inferring from the chemical index of alteration and plagioclase index of alteration (PIA), the Yewa and western Badagry creeks have been moderately to intensely weathered and incipient weathering was identified in the eastern end of Badagry Creek.

14

Sedimentological study of the Nikolčice Formation : evidence of the Middle Jurassic transgression onto the Bohemian Massif (subsurface data)

Nehyba S., Opletal V.

Geological Quarterly

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2017

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Vol. 61, No. 1

138--155

EN

The Jurassic sedimentary succession along the eastern margin of the Bohemian Massif starts with mostly fluvial deposits of the Gresten Formation and continues after marine transgression with the deposition of the Nikolčice Formation (Middle Jurassic, Callovian). The provenance and depositional environment of the Nikolčice Formation showed that deposition occurred within offshore, transitional zone, shoreface, foreshore and littoral sand bar environments; however, shoreface and foreshore deposits dominate in the cores studied. The crystalline units along the eastern margins of the Bohemian Massif represent the primary source of deposits of the Nikolčice Formation. An important role was played by acidic and intermediate plutonites and highly metamorphosed metasedimentary rocks (granulite and amphibolite metamorphic facies), which indicates an advanced stage of erosion of the source area. The role of volcanic and intrusive rocks was small. The primary source was followed by an additional recycled source from older sedimentary rocks (especially the Moravo-Silesian Paleozoic deposits – the Líšeň Formation, the Myslejovice Formation). A similarity of the source areas for the Nikolčice Formation and the underlying Gresten Formation was recognized. Identified differences in their source areas are mainly explained by varied erosional levels due to successive exhumation of the source Variscan orogen and possibly also by an expansion of the source area.

15

Chromian spinels from the Magura Unit (Western Carpathians, Eastern Slovakia) : their petrogenetic and palaeogeographic implications

Bónová K., Špisiak J., Bóna J., Kováčik M.

Geological Quarterly

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2017

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Vol. 61, No. 1

3--18

EN

Detrital chromian spinels in sedimentary rocks provide much information concerning the tectonics of their parental ultrabasic rocks. Chromian spinels occurring in the Eocene to Oligocene depos its from the Magura Nappe were exam i ned to provide some constraints on the history of the Magura Basin. The Magura Nappe is a part of the Flysch Belt belonging to the External Western Carpathians. The Magura Nappe is separated by a narrow zone associated with the Pieniny Klippen Belt and is divided into three principal tectono-lithofacies units (from the S to N): the Krynica, Bystrica and Rača units. Cr-spinel is a common accessory mineral (2.3-5.9 vol% of heavy mineral spectra) in the siliciclastic rocks of the Rača and Krynica units. In terms of texture and chemical composition, two types of Cr-spinels were recognized: unaltered and altered. Unaltered spinels were found to contain silicate inclusions such as chromio-pargasite, enstatite, diopside, pargasite, plagioclase and olivine (forsterite). The chromian spinels show wide variations in compositional parameters such as Cr# (0.3-0.7), Mg# (0.3-0.7), TiO2 (<0.03-1.9 wt.%) and Fe2+/Fe3+ (2.5-13) whereas the differences between the Rača and Krynica units are in- significant. These parameters suggest a peridotitic and volcanic origin of the spinels, respectively. The ophiolite source consisting of harzburgitic mantle peridotites was developed mainly in a supra-subduction zone setting; volcanic spinels indicate an origin in mid-ocean ridge basalts, back-arc basin basalts and sporadically in ocean-island basalts. Concerning their geochem i cal features, we propose that during the Eocene to Early Oligocene, the ophiolitic detritus in the eastern part of the Magura Basin deposits may have been derived from a source area located in the Fore-Marmarosh Suture Zone (Eastern Carpathians) that is considered an equivalent of the Black Flysch and Ceahlau units. Some Cr-spinels found in the Eocene sedimentary successions may have resedimented from older Late Cretaceous-Paleocene formations of the Magura Unit, which are considered as reworked sedimentary material from the Pieniny Klippen Belt.

16

Rare earth elements distribution in fine-grained deposits from the uppermost Triassic and Lower Jurassic of the Polish Basin : provenance and weathering of source area

Brański P., Mikulski S. Z.

Geological Quarterly

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2016

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Vol. 60, No. 2

441--450

EN

Nineteen samples of uppermost Triassic and Lower Jurassic claystones and mudstones, which were formed in the epicontinental Polish Basin, were analysed by inductively coupled plasma mass spectrometry (ICP-MS) for rare earth elements (REE) and other selected trace elements (Sc, Y, Th, Zr and U). The results indicate that the source of most of the claystones and mudstones studied were sedimentary rocks of the upper continental crust of old cratonic areas, where the protolith had a mainly felsic character. However, in the latest Triassic a characteristic layer formed, implying significant input from mafic volcanic protolith. It was also found that moderately intense chemical weathering usually favoured increased concentration of the rare earths. Extremely strong hydrolysis, related to episodes of very hot and humid climate (greenhouse events), caused conspicuous impoverishment in REE in residual clays. Weathering and recycling processes modified the composition of REE to some extent, but generally did not obliterate the original characteristics of the protolith. In some samples, enrichment in rare earth elements was observed, caused by admixtures of accessory minerals (being a main carrier of REE) and/or increased sorting during recycling.

17

Heavy minerals from sedimentary rocks of the Malcov Formation and their palaeogeographic implications for evolution of the Magura Basin (Western Carpathians, Slovakia) during the Late Eocene–Late Oligocene

Bónová K., Bóna J., Kováčik M., Laurinc D.

Geological Quarterly

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2016

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Vol. 60, No. 3

675--694

EN

Detrital heavy minerals separated from the Malcov Fm. deposits (Magura Nappe) indicate their source rocks and areas. The heavy mineral assemblages predominantly consist of garnet, zircon, tourmaline, rutile and Cr-spinel. EPMA analyses reveal a few groups of garnets: zoned and unzoned Grs almandines, Prp-Sps almandines, unzoned Prp almandines, almandines, Sps almandines and rare zoned spessartine grains (~85 mol% Sps). The garnet composition indicates that gneisses, mica schists, amphibolites and granites were their main source rocks, but low-grade metapelites with Mn mineralisation probably contributed as well. The detrital dravitic tourmalines were mostly derived from paragneisses and mica schists. Cr-spinel indicates a volcanic source. Based on heavy mineral assemblages, coupled with palaeoflow analysis, we conclude that the Marmarosh Massif and Fore-Marmarosh Suture are the most probable source areas. Aditionally, the Malcov sedimentary basin was supplied by material from the crystalline complexes of the Tisza Mega-Unit and Pieniny Klippen Belt (PKB). The bulk of the clastic deposits comprise classical turbidites. These lithofacies were deposited from either turbidity currents or from concentrated density flows. The palaeoflow record is varied and highlights the contribution of sedimentary material from several directions and/or diversion of gravity currents from the main flow direction (SE–NW). The marginal parts of the Malcov sub-basins were formed of deformed and uplifted older formations of surrounding units of the Magura Nappe and PKB (submerged ridges). Older (Late Cretaceous to Eocene) flysch sediments may have been redeposited from these ridges to neighbouring sub-basins in a transverse direction (NE–SW).

18

Geochemistry of Upper Cretaceous of the Bozeş Formation (Apuseni Mts., Romania) : provenance implications

Zaharia L., Balc R., Stremţan C. C., Socaciu A.

Geological Quarterly

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2016

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Vol. 60, No. 3

746--757

EN

A whole-rock geochemical study was carried out on sandstones from the Upper Cretaceous Bozeş Formation in the southeastern part of the Apuseni Mountains (Romania) in order to constrain their provenance and depositional setting. The geochemical results were compared and integrated with previously reported provenance indicators, such as framework composition and heavy mineral assemblages. The chemical composition is similar for all samples investigated, with limited ranges for both major oxides and trace elements. The sandstones are potassic (Na2O/K2O < 1) and can be classified mainly as arenites with a few greywackes. Their immature to relatively mature character is revealed by the SiO2/Al2O3 ratios, ranging between 3.90 and 11.25, as well as their high Sr/Rb ratios. The source rocks were affected by weak to moderate chemical alteration, as indicated by the specific index (CIA), with values between 47 and 71. The detrital material was influenced by a little hydraulic sorting during transportation, while post-depositional eftects were limited to K-metasomatism. Two major potential source types were identified based on the chemical composition of the samples studied: a felsic magmatic arc and a recycled, quartzose metasedimentary basement. Our data indicate that the depositional setting is likely to be on a convergent margin. The results are consistent with uplifted and exhumed Transylvanian basement as the major source area.

19

Petrographic and geochemical study of the Maastrichtian Ajali Sandstone, North Central Nigeria

Ogala J. E., Olobaniyi S. B., Omo-Irabor O. O., Adaikpoh E. O.

Geological Quarterly

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2015

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Vol. 59, No. 1

79--90

EN

he Upper Cretaceous Ajali Sandstone is an extensive stratigraphic unit of the Anambra Basin in southern Nigeria. It consists of friable, white cross-bedded sandstones exhibiting a fining upward sequence. Structures such as bioturbation, planar and herringbone cross beds indicate variability in depositional environment ranging from fluviatile to deltaic. Petrographic and geochemical compositions (major and trace elements) of these sandstones have been investigated to determine their provenance, tectonic setting and weathering conditions. Fifteen sandstone samples examined are rich in quartz but poor in feldspar and lithic fragments. Texturally, the framework grains of the sandstones are fine- to medium-grained, sub-angular to sub-rounded, moderately sorted to poorly sorted, positively skewed and leptokurtic. The sandstones are texturally immature as depicted by their sub-angular edges of grains, but mineralogically mature in terms of high percentage of quartz. The high chemical index of alteration (CIA) values (71.0–99.2%) for these sandstones suggests that they were derived from highly weathered rocks in the source area. The composition of the major oxides in the sandstones revealed that SiO2 (49.1–99.7%), Al2O3 (0.2–30.3%), Fe2O3 (0.4–1.8%) and TiO2 (0.06–3.2%) were the most abundant elements in all sandstone samples indicating a high detrital quartz and clay mineral content. The Al2O3/TiO2 ratios (1.47 to 12.48), Ti/Zr (6.48–18.63) and Zr/Cr (2.24–22.36) suggest that the sandstones were derived from variable basement complex rocks, including some contribution from mafic or ultramafic components. Inferences from the plots of K2O/Na2O versus SiO2 indicated a passive margin tectonic setting for the sandstones. The high loading of CaO and Na2O in more than 50% of the samples is indicative of terrigenous input, mainly in the form of carbonates and silicates. These results are generally consistent with a derivation of the sandstones from adjacent igneous and metamorphic basement complexes (Cameroon–Adamawa highlands and Oban Massif) while the extensive and blanket-like geometry of the Ajali Sandstone is indicative of an excellent reservoir for groundwater in the Anambra Basin.

20

Nd and Sr isotopic evidence for provenance of clastic material of the Upper Triassic rocks of Silesia, Poland

Konieczna N., Belka Z., Dopieralska J.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 4

675--684

EN

Nd and Sr isotope data were used to characterize the sources of the Upper Triassic (Keuper) siliciclastic rocks of Silesia in southern Poland. This continental succession, consisting predominantly of fine-grained mud- stones and siltstones, yields a remarkably uniform Nd isotopic composition. Nd model ages T2DM vary from 1.56 to 1.69 Ga and εNd values are in the range from –8.9 to –11.2, documenting old crust contribution in the provenance. In contrast, the Sr isotopic composition (87Sr/86Sr) of the clastics exhibits a relatively large variation from 0.710 to 0.723. The isotopic compositions indicate that the southern part of the Germanic Basin in Silesia was supplied with clastic material from the Bohemian Massif. The axis of the drainage area must have crossed from SW to NE the Saxothuringian units of the East Sudetes and most probably also the area of the Tepla–Barrandian Unit. There is no indication of any sediment transport from the Moravo-Silesian Belt and the Fore-Sudetic Block. It seems, that the Palaeozoic rocks of the latter domain must have been buried completely during Late Triassic times.