Wyniki wyszukiwania - BazTech

1

Carbonate-clastic sediments of the Dudziniec Formation in the Kościeliska Valley (High-Tatric series, Tatra Mountains, Poland) : role of syndepositional tectonic activity in facies development during the Early and Middle Jurassic

Jezierska A., Łuczyński P., Staśkiewicz A.

Geological Quarterly

|

2016

|

Vol. 60, No. 4

869--880

EN

Sediments of the Dudziniec Formation (Lower Jurassic – Aalenian) outcropping in the Kościeliska Valley (autochthonous unit of the High-Tatric series) are represented by a range of mixed carbonate-clastic deposits. Seven lithofacies have been distinguished based on lithology, sedimentary structures, colour and composition of intra- and extraclasts, with sandstones and crinoidal limestones as end members of a continuous spectrum of facies. The study area represents a shallower part of the sedimentary basin located in the vicinity of source areas, as compared to the Chochołowska Valley region located in the west. Facies characteristics and distribution were controlled mainly by synsedimentary tectonic activity, with sandy varieties representing periods of faulting with enhanced influx of extraclasts, and with crinoidal limestones corresponding to intervals of relative tectonic stability. Such influence of synsedimentary tectonics on the deposition in the Early Jurassic strongly resembles the Middle Jurassic development in the High-Tatric area. Neptunian dykes cutting the Dudziniec Formation, and most probably filled by Lower Jurassic sediments, are yet another indication of tectonic instability of the area in the Early Jurassic.

2

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

|

2015

|

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.

3

Pliocene-Quaternary stratigraphy and sedimentation at the Neretva River Mouth, on Croatian Adriatic Coast

Balic D., Malvic T.

Geological Quarterly

|

2013

|

Vol. 57, No. 2

233–-241

EN

The Adriatic Sea is an epicontinental, closed sea, part of the Mediterranean. It formed in the Late Miocene, and ended structurally during the Pliocene and Quaternary, when most of its sediments were deposited. The larger Pliocene and Quaternary depressions occur mostly by the western coast, where the deposits are several thousand metres thick, and were sourced from the Alps and the Apennines. The east coast is characterised by the large and elongated Dinarides Mts., that have continental drainage extremely close to the shoreline and a very small erosional rate. Consequently, eastern inflows were and are very short, including strongly tidal estuaries that erode only small volumes of mostly carbonate detritus, adjacent to frontal islands or mountains, with restricted depositional areas. The Neretva River deposits make up part of the largest contemporary delta system on the eastern Adriatic coast, and have been analysed in this study using three seismic sections and one exploration well. These deposits are recognized inside the Neretva and Korčula channels, assuming that processes operating during Quaternary glacial phases shifted the delta tens of kilometres to the west in the past on several occasions.

4

Sedimentary characteristics of the Hüdaý Formation (Early Cambrian) within the Aydincik (ÝÇEL) area, S Turkey

Eren M., Öner F.

Annales Societatis Geologorum Poloniae

|

2000

|

Vol. 70, No. 3-4

251-259

EN

The study area is located in Aydýncýk (ÝÇEL) area where Early Cambrian rocks are represented by the Hüdai Formation. The formation represents three different parts in the vertical sequence which has a thickness of approximately 830 metres. The basal part of the formation consists of a rhytmic alternation of horizontal laminated sandstone, ripple trough cross-laminated sandstone, mixed sandstone-shale, and rarely metashales. The middle part comprises dominantly metashales. The upper part is made up by an alternation of horizontal laminated sandstone, mixed sandstone-shale and rarely metashales. Vertical variations in the formation is caused by marine transgressious and regressious, and by fluctuations in sediment supply. Lower to middle parts of the formation characterize a fining-upward sequence, and middle to upper parts display a coarsening-upward sequence. In the Hüdai Formation, four lithofacies are recognized based on lithology and sedimentary structures. These are (1) horizontal laminated sandstone (predominantly quartzarenite) indicating deposition from tidal currents during the high velocity phases of tidal cycles; (2) ripple cross-laminated sandstone (predominantly quartzwacke) deposited in lower part of intertidal (sand-flat) environment; (3) mixed sandstone-shale revealing deposition in mid-intertidal flat environment; and (4) shale (or metashale) deposited mainly in upper intertidal (mudflat) environment.