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Lacustrine deltas and subaqueous fans: almost the same, but different – a review

Gruszka Beata, Zieliński Tomasz

Geologos

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2021

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Vol. 27, No. 1

43--55

EN

Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and subaqueous fans are highlighted.

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Secular and catastrophic processes reflected in sediments of the Suchedniów water reservoir, Holy Cross Mountains (Poland)

Przepióra Paweł, Kalicki Tomasz, Aksamit Michał, Biesaga Piotr, Frączek Marcin, Grzeszczyk Paulina, Malęga Emanuela, Chrabąszcz Mariusz, Kłusakiewicz Edyta, Kusztal Piotr

Geologos

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2019

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Vol. 25, No. 2

139--152

EN

The Suchedniów water reservoir is located in the central section of the River Kamionka in the northern part of the Holy Cross Mountains of central Poland. This area once belonged to the Old Polish Industrial District that, during the Middle Ages, was very intensively developed by iron metallurgy. Many forges and mills along the rivers used water power, which led to the construction of an anthropogenic, small-scale water retention system. At the beginning of the twentieth century many of these reservoirs were drained after the collapse of metallurgical activities. The present-day reservoir was built in 1974 and drained in 2017. Research into the drained basin has documented various forms and sediments, some of which record present-day depositional processes (fire proof clay layer, inland fan delta), while others represent the historical period (lacustrine sediments of older reservoirs). Traces of catastrophic events have been preserved as well; an assemblage of megaripples marks the sudden drainage caused by a dam break in 1974.

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A new etching trace from the Savignone Conglomerate (Oligocene), NW Italy, probably produced by limpet gastropods

Uchman A., Rattazzi B.

Acta Geologica Polonica

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2018

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Vol. 68, no. 4

651--662

EN

A new ichnogenus and ichnospecies (Solealites ovalis) of etching trace is preserved on the surfaces of clasts from the Savignone Conglomerate (Oligocene) in the Palaeogene Piemonte Basin in NW Italy. It is a shallow, oval depression with a central elevation, which was produced probably by limpet gastropods and served as their home scar, but other gastropods or even sea anemones are not excluded as the trace makers. The conglomerate is interpreted as a deposit of a fan delta, whose clasts have been bioeroded in an intertidal and shallow subtidal shore zone and redeposited to the deeper sea.

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Foreland provenance of thick conglomerates in the early stage of the Carpathian Foredeep development : the case of the Sloboda Conglomerate (Lower Miocene), western Ukraine

Oszczypko N., Uchman A., Bubniak I.

Geological Quarterly

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2012

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Vol. 56, No. 4

789--802

EN

The upper part of the Lower Miocene Sloboda Conglomerate, a 250–1400 m thick unit, was deposited mainly on an alluvial fan and fan delta during the early stages of Carpathian Foredeep development. During of the Old Styrian overthrust movements of the Carpathian orogen, a forebulge was formed, which supplied clasts to the conglomerate. The clasts are dominated by Late Proterozoic–Early Cambrian phyllites, while Paleozoic carbonates are common, and Mesozoic and other rocks are rare. The source area formed mainly by a prolongation of the Małopolska Massif that was involved in the forebulge; this was located close to a palaeovalley cut into Mesozoic and Paleozoic rocks, buried under younger strata. Additional material was derived from the advancing front of the Carpathian Flysch nappes.

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Eustatic and tectonic control on late Eocene fan delta development (Orava Basin, Central Western Carpathians)

Starek D., Sliva L’., Vojtko R.

Geological Quarterly

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2012

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Vol. 56, No 1

67-84

EN

The evolution of the Central Carpathian Paleogene Basin (CCPB) reflects an important role of relative sea level changes on a tectonically active basin margin. After the initial upper Lutetian/Bartonian transgression, the next regressive-transgressive cycle played a key role in a formation of the late Eocene fan delta facies associations in the southern Orava region of Northern Slovakia. Detailed sedimentary analysis allowed the separation of the following three facies associations which represent distinct depositional environments: alluvial fan (subaerial fan delta; Unit 1); subaqueous fan delta (Unit 2); and prodelta/slope and basin (Unit 3). The first stage of delta development is connected with eustatic sea level fall at the Bartonian/Priabonian boundary, accompanied by subaerial exposure, fluvial incision and deposition of alluvial fan sediments. Subaerial deposition was characterized by a variety of mass flow conglomerates with a red muddy matrix, interfingering with stream or sheetflood deposits. The next stage of the delta corresponds to high-amplitude transgression related to rapid tectonic subsidence along the CCPB margins during the Priabonian. The vertical arrangement of facies suggests retrograde delta development that shows rapid submergence of the subaerial parts and onlap of subaqueous mass flow conglomerates, often reworked by waves or wave-induced shallow-marine currents. Continuous deepening of the depositional environment during the late Priabonian/early Rupelian led to the relatively rapid superposition of prodelta/slope and basin facies associations by slowly accumulated hemipelagic deposis.

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Tectonic evolution of the late Cretaceous Nysa Kłodzka Graben, Sudetes, SW Poland

Don J., Gotowała R.

Geologia Sudetica

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2008

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Vol. 40

51-63

EN

The Nysa Kłodzka Graben, located in the Sudetes of SW Poland, developed as a result of Coniacian (middle Upper Cretaceous) N-trending faulting of the Variscan crystalline basement rocks that comprise the crest of the Orlica-Śnieżnik Dome. The graben was transgressed by a late Cretaceous sea that encroached during the Cenomanian from the northwest. Up to 700 m of Coniacian shales, sandstones and conglomerates were deposited in the graben, with shales (the ~500 m thick Idzików 'clays') dominating the graben's central section. On the western side of the graben, shales grade upwards to greywackes in a style that resembles a turbidite sequence; on the eastern side, shales are overlain by sandstones and conglomerates (the Idzików conglomerates) that represent extensive late Cretaceous fan deltas. These within-graben fan deltas date the onset of fault-block movements that uplifted the Sudetes region during the late Cretaceous-Cenozoic. By the end of the Cretaceous, both the sedimentary infill and the underlying Cenomanian and Turonian strata were steepened at the graben margins and were gently folded, the fold axes paralleling the graben's marginal faults. Subsequent Cretaceous-Paleocene ('Laramian') deformations resulted in NW-trending reverse faulting, which restructured the earlier N-S template of the graben, and in transcurrent faults, which cut the N-trending folds, modified the north and south ends of the graben and strongly affected the graben's western walls. The total thickness of the Upper Cretaceous strata of the Nysa Kłodzka Graben is 3 times that of the Intra-Sudetic Synclinorium, implying that the two units developed independently.