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Wpływ przerostów piaszczystych w węglu brunatnym na działalność górniczą : przykład ze złoża „Pątnów IV” (okolice Konina) w środkowej Polsce

Dziamara Mariusz, Glacová Veronika, Klęsk Jakub, Marschalko Marian, Wachocki Robert, Widera Marek

Przegląd Geologiczny

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2022

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Vol. 70, nr 5

376--383

EN

Lignite from the “‘Pątnów IV” deposit is mined in the Jóźwin IIB opencast by the Konin Lignite Mine. Within the exploited 1st Mid-Polish lignite seam, there are layers of sand with a thickness of over 5 m. Based on field observations and geological mapping, these sandy interbeddings are interpreted as deposits of two or three crevasse splays of different ages. Due to such a large thickness of sands, only the upper bench of the lignite seam is currently mined in the Jóźwin IIB opencast. On the other hand, the exploitation of the lower and middle lignite benches of this seam is unprofitable at present.

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Rare-earth and trace elements of the lower Cambrian–Lower Cretaceous siliciclastic succession of NE Gondwana in Jordan : from provenance to metasomatism

Amireh Belal S., Saffarini Ghazi A., Amaireh Mazen N., Jarrar Chaleb H., Abed Abdulkader A.

Annales Societatis Geologorum Poloniae

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2022

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Vol. 92, No. 2

109--158

EN

The present bulk-rock geochemical study aims to answer some questions concerning the distribution and variability of trace elements (TEs) and rare earth elements (REEs) in the lower Cambrian–Lower Cretaceous sandstones and mudstones of NE Gondwana in Jordan. The study proved that the REE and the TE distribution patterns in both detrital and authigenic, light and heavy minerals are controlled principally by the source-rock provenance, followed by an interplay of many factors: chemical weathering, recycling, hydraulic sorting, locally low-temperature, hydrothermal metasomatism, depositional environment and redox conditions, and diagenesis. On the basis of specific trace elements, trace-element ratios, and petrographic proxies, the provenance is constrained to be mainly felsic-, rarely mafic granitoids of the Arabian-Nubian Shield, and less commonly, recycled Palaeozoic and Mesozoic siliciclastic strata. REEs are hosted mainly in zircon, Ti-bearing minerals, and partly in clay minerals. They were depleted by both chemical weathering and recycling; nevertheless, they were enriched by subsequent hydraulic sorting and low-temperature, hydrothermal metasomatism. Chemical weathering initially depleted zirconium. However, this was counteracted by subsequent enrichment through recycling, hydraulic sorting, and low-temperature, hydrothermal metasomatism. The fractionation of the other TEs, due to these sedimentological factors during the genesis of subarkosic arenites, quartz arenites and mudstones, is discussed and some conclusions are derived. The Eu negative anomaly was enhanced significantly by recycling and low-temperature, hydrothermal metasomatism. Scandium abundance increased with decreasing grain size from coarse sand to the mud fraction. The recorded REE and TE fractionation might also apply to siliciclastics in similar, geological environments.

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First find of biogenic activity in the Palaeoproterozoic of the Singhbhum craton (E India)

Loon A. J., Mazumder R.

Geologos

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2013

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Vol. 19, No. 3

185--192

EN

The Palaeoproterozoic succession of the Singhbhum craton in E. India was hitherto considered as almost entirely siliciclastic and partly volcanogenic. Here we describe, from the fine-grained, tidally influenced shale facies of the Palaeoproterozoic Chaibasa Formation (2.1-1.6 Ga), a fine, originally more or less horizontal, wavy to strongly undulating (later locally deformed) lamination. Investigation of these laminae shows that they must be ascribed to the accumulation of fine particles on microbial mats that covered a sandy substrate. The structures must therefore be considered as stromatolites, features that are accepted as proof of the presence of micro-organisms, in this case most probably cyanobacteria. The interpretation of biogenic activity is supported by microscopic analysis. It is the first description of traces left by biogenic activity that took place in the Palaeoproterozoic of the Singhbhum craton.

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Soft-sediment deformation structures in siliciclastic sediments: an overview

Loon A. J.

Geologos

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2009

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Vol. 15, No. 1

3--55

EN

Deformations formed in unconsolidated sediments are known as soft-sediment deformation structures. Their nature, the time of their genesis, and the state in which the sediments occured during the formation of soft-sediment deformation structures are responsible for controversies regarding the character of these deformations. A definition for soft sediment deformation structures in siliciclastic sediments is therefore proposed. A wide variety of soft-sediment deformations in sediments, with emphasis on deformations in siliciclastic sediments studied by the present author, are described. Their genesis can be understood only if their sedimentary context is considered, so that attention is also paid to the various deformational processes, which are subdivided here into (1) endogenic processes resulting in endoturbations; (2) gravity-dominated processes resulting in graviturbations, which can be subdivided further into (2a) astroturbations, (2b) praecipiturbations, (2c) instabiloturbations, (2d) compagoturbations and (2e) inclinaturbations; and (3) exogenic processes resulting in exoturbations, which can be further subdivided into (3a) bioturbations - with subcategories (3a’) phytoturbations, (3a’’) zooturbations and (3a’’’) anthropoturbations - (3b) glaciturbations, (3c) thermoturbations, (3d) hydroturbations, (3e) chemoturbations, and (3f) eoloturbations. This subdivision forms the basis for a new approach towards their classification. It is found that detailed analysis of soft-sediment deformations can increase the insight into aspects that are of importance for applied earth-scientific research, and that many more underlying data of purely scientific interest can, in specific cases, be derived from them than previously assumed. A first assessment of aspects that make soft-sediment deformation structures in clastic sediments relevant for the earth sciences, is therefore provided.

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Predictive diagenetic clay-mineral distribution in siliciclastic rocks as a tool for identifying sequence boundaries in non-marine successions: the Coalspur Formation, west-central Alberta

Khidir Ahmed, Catuneanu Ovtavian

Geologos

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2009

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Vol. 15, No. 3-4

169--180

EN

The study of upper Cretaceous - lower Tertiary fluvial deposits of the Coalspur Formation in the Foothills region of west-central Alberta reveals that the distribution of early authigenic kaolinite has a well-defined relation to the sequence stratigraphic framework. In this context, it has been observed that the kaolin mineral content increases in sandstones lying below subaerial unconformities, which mark the most significant stratigraphic hiatuses and hence the sequence boundaries in fully fluvial successions. The increased abundance of authigenic kaolinite immediately below sequence boundaries may have been caused by the infiltration of meteoric water during times of subaerial erosion, resulting in the dissolution of unstable minerals (e.g., micas and feldspar) and the formation of kaolinite and secondary porosity. It is therefore suggested that the change in clay mineral assemblages in the stratigraphic section depends in part on the position of the analyzed sandstone samples relative to the sequence boundaries. In a larger context, the method of using authigenic clays to delineate depositional sequences in non-marine successions needs to be evaluated on a case-by-case basis, as the diagnostic early diagenetic minerals underlying the sequence boundary may change as a function of palaeoclimate and also as a function of late diagenetic processes.