Sedimentary environment and tectonic controls of the Snochowice Beds (Lower Jurassic, western margin of the Holy Cross Mountains, Poland)

Abstract

The Snochowice Beds rep re sent the low er most part of the Lower Ju ras sic suc ces sion in the west ern part of the Me so zoic mar gin of the Holy Cross Moun tains (Cen tral Po land). This thick, grav elly has a dif fer ent lithological char ac ter to other Lower Ju ras sic sandy and fine-grained de pos its. Eight lithofacies have been dis tin guished, mainly grav elly and sandy, grouped into four ge netic as so ci a tions: Mmas sive grav els, in ter preted as clast-rich de bris flow de pos its, G -hor i zon tally to cross-strat i fied grav els, in ter preted as grav elly bars and bedforms, S -cross-strat i fied and mas sive sand stones, in ter preted as sandy bars and bedforms and F -mas sive mudstones and claystones, gen er ally fine-grained de pos its, in ter preted as overbank de pos its. Anal y sis of depositional ge om e try and lithofacies suc cessions al lowed re con struc tion of the sed i men tary en vi ron ment: land forms of al lu vial fan type, formed mainly by braided river pro cesses and rarely by sed i ment grav ity flows. A de crease in the thick ness and con tent of grav elly lithofacies to wards the north and north-east is doc u mented. Anal y sis of trans port di rec tions has re vealed that the clastic ma te rial was trans ported to ward the north and north-east, perpen dic u lar to the main faults fring ing the ba sin. Depositional ge om e try fa cies and palaeocurrent pat terns of the Snochowice Beds in dicate that sed i men ta tion was con trolled by tec tonic ac tiv ity. Małgorzata Kozłowska, In sti tute of Ge ol ogy, Uni ver sity of War saw,

Swelling and flow of expanding clays as a cause for non‐tectonic deformations in a glacial–interglacial environment: Holy Cross Mountains, Poland

“…It is important to emphasize the lithologically diverse contact of Upper Triassic sediments with the deposits of the Middle Jurassic. In the studied area, red claystones and mudstones of Keuper are in contact with Callovian gaizes, but in other places, for example, further southeast, the Upper Triassic is represented by yellowish‐grey sandstones that are directly covered by dark‐grey clays of Bathonian age (Kozłowska et al, 2016). Palynological studies have shown that these grey deposits correspond to the Rhaetian character of the waning episode of Triassic sedimentation (Kozłowska et al, 2016).…”

“…The Upper Triassic deposits are siliciclastics (claystones, mudstones and sandstones of fluvial, lacustrine and playa origin) with a wide range of colours (mainly red and greenish) belonging to an informal lithostratigraphic unit-Keuper (Deczkowski & Franczyk, 1988;Fijałkowska, 1992;Fijałkowska-Mader, 2013;Kopik, 1970;Pawłowska, 1979;Pie nkowski, 2009). Because these deposits have a negligible fossil content, their exact stratigraphic position is imprecise, although they are commonly referred to as 'Rhaeatian' (Krupnik et al, 2014;Marcinkiewicz et al, 2014;Marcinkiewicz & Orłowska-Zwoli nska, 1985Orłowska-Zwoli nska, 1983) (Kozłowska et al, 2016). Palynological studies have shown that these grey deposits correspond to the Rhaetian character of the waning episode of Triassic sedimentation (Kozłowska et al, 2016).…”

“…Because these deposits have a negligible fossil content, their exact stratigraphic position is imprecise, although they are commonly referred to as 'Rhaeatian' (Krupnik et al, 2014;Marcinkiewicz et al, 2014;Marcinkiewicz & Orłowska-Zwoli nska, 1985Orłowska-Zwoli nska, 1983) (Kozłowska et al, 2016). Palynological studies have shown that these grey deposits correspond to the Rhaetian character of the waning episode of Triassic sedimentation (Kozłowska et al, 2016). In those areas where the Upper Triassic sediments are dominated by sandstones instead of claystones, steepening of Callovian layers does not occur.…”

Diagenesis and the Conditions of Deposition of the Middle Jurassic Siderite Rocks from the Northern Margin of the Holy Cross Mountains (Poland)

“…Mineralogical studies of siderite interbeds in Middle Jurassic siliciclastic rocks from the Polish Lowlands were conducted by Maliszewska [19] and Maliszewska et al [20][21][22][23]. Kozłowska's studies provided petrographic analyses of siderite rocks from the northeastern margin of the Holy Cross Mountains [24][25][26][27][28][29][30] and the Częstochowa region [26,[28][29][30][31].…”

“…In recent years, Feldman-Olszewska [26,31] and Leonowicz [37][38][39][40] conducted sedimentological analyses of Middle Jurassic deposits in the Częstochowa region. Single publications contain sedimentological data on rocks containing Middle Jurassic siderite interbeds in the northeastern margin of the Holy Cross Mountains [25].…”