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History of sedimentation of the Nida Gypsum deposits (Middle Miocene, Carpathian Foredeep, southern Poland)

100%

Bąbel M.

tom Vol. 43, Nr 4

429-447

The Nida Gypsum deposits are the best exposed in Poland part of the Middle Miocene (Badenian) evaporites of the Carpathian foreland basin. These deposits record various shallow water (<< 5 m) evaporative environments. The facies sequence in the lower part of evaporites reflects shallowing (up to emersion) and than deepening accompanied with salinity rise up to halite precipitation. The salinity rise was arrested by refreshment promoting subaqueous dissolution of sodium chloride. This event was followed by the second large salinity rise and then final dilution of brine which finished evaporative sedimentation. The described two saline cyclothems are recognizable over large area of Carpathian foreland basin.

Na podstawie rozprzestrzenienia 5 wyróżnionych pierwotnych facji (M. Bąbel, 1999b), reprezentowanych przez gipsy szklicowe, rumosze kryształów gipsu, gipsy trawiaste, szablaste i mikrokrystaliczne, oraz szczegółowe interpretacje środowisk sedymentacji ich 12 subfacji (tab. l; M. Bąbel, 1999b), odtworzono historię sedymentacji środkowomioceńskich gipsów Ponidzia. Osady te tworzyły się w płytkim (0-5 m) basenie ewaporacyjnym. Stałe pionowe następstwo facji w dolnej części profilu: gipsy szklicowe-trawiaste-szablaste-mikrokrystaliczne, jest wynikiem spłycenia (a lokalnie wynurzenia prowadzącego do powstania rumoszy kryształów pokrywających gipsy szklicowe) i następującego po nim pogłębienia. Zmiany głębokości były stowarzyszone ze wzrostem zasolenia aż do wytrącenia halitu w gipsach mikrokrystalicznych. Wzrost zasolenia został przerwany rozcieńczeniem solanek, które wywołało rozpuszczenie wcześniej osadzonego halitu. Ponowny wzrost zasolenia wyraził się powtórzeniem sekwencji facji: gipsy trawiaste-szablaste-amikrokrystaliczne w górnej części profilu. Dolne ogniwa tej sekwencji mają zredukowaną miąższność i są obecne wyłącznie na północny badanego terenu. Wyróżnione dwa cykloteny solne można rozpoznać na znacznym obszarze zapadliska przedkarpackiego również na Ukrainie.

Braided-river and hyperconcentrated-flow deposits from the Carboniferous of the Lublin Basin (SE Poland) - a sedimentological study of core data

100%

Waksmundzka M. I.

2012

tom Vol. 18, No. 3

135--161

Fining-upwards cyclothems found in five boreholes in the Carboniferous (Lower Bashkirian) of the Lublin Basin were analysed sedimentologically. It was established that the cyclothems represent fluvial deposits, and the lithofacies were grouped into lithofacies associations. Most lithofacies associations represent three types of sand-bed braided rivers: (1) high-energy, (2) deep and (3) distal sheetflood-affected. Other associations represent hyperconcentrated flows. Both coarse-grained (type I) and fine-grained (types IIa and IIb) occur among the fining-upward cyclothems. The formation of most thick cyclothems was related mainly to allocyclic factors, i.e. a decrease in the river’s gradient. The thickest fining-upward cyclothems are characteristic of hyperconcentrated flows and braided-river channels. The aggradation ratios were commonly high. During the early Namurian C and early Westphalian A (Early Bashkirian), the eastern part of the Lublin Basin was located close to the source area. The sedimentary succession developed due to a transition from high-energy braided-rivers and hyperconcentrated flows to lower-energy braided rivers, controlled by a rise of the regional base level.

A putative Tournaisian and Visean volcanic-sedimentary succession in the Lublin Basin, SE Poland: depositional processes, petrological characteristics and sequence stratigraphy

80%

Waksmundzka M. I. , Kozłowska A. , Pańczyk M.

tom Vol. 71, no. 3

305--344

The aim of this study was to establish the stratigraphic extent of a putative Tournaisian Stage within the Carboniferous succession in the Lublin Basin. The oldest part of the succession, known as the Huczwa Formation and comprising depositional sequences 1-4, was investigated based on lithofacies analysis, sequence stratigraphy and petrographic studies. The article provides descriptions of depositional sequences, parasequences (cyclothems) and lithofacies that were formed in a range of environments (elements of depositional architecture) and as a result of volcanic processes - lava and pyroclastic eruptions and chemical weathering of their products. Correlation of the sequence stratigraphy to the West European and global Carboniferous chronostratigraphic divisions, as well as to the Khoriv suite in the Lviv-Volyn Basin in adjacent Ukraine, indicates a putative late Tournaisian age for sequence 1, and a late Visean age for sequences 2-4. There is a stratigraphic gap between sequences 1 and 2, spanning probably the uppermost Tournaisian and the lower and middle Visean. The upper Tournaisian is represented by the FRST-LST deposits of sequence 1, comprising mainly volcaniclastic conglomerates and sandstones developed in braided-river channels and incised valleys with hyperconcentrated flow processes. These deposits are represented by polymictic paraconglomerate and lithic/sublithic/subarkose arenites or sublithic wackes, and contain predominantly grains of acidic and alkaline volcanic and igneous rocks. This material probably came from the Łuków-Wisznice Elevation and the Volynian Polesia region, located to the NE and E of the Lublin Basin. In the uppermost part of sequence 1, volcanic rocks and tuffs appear which developed during the activity of at least three volcanic cones in the Lublin Basin. The volcanoes were the source of alkaline lavas in the central and SW areas of the basin, and of acidic lavas in the SE area, previously undescribed. The Visean sequences 2-4 consist of the FRST-LST sediments deposited within incised valleys. The TST and HST deposits accumulated mainly in a shallow ramp-type carbonate shelf, shallow clayey shelf and deltaic environments.