Commune: Tomaszów Mazowiecki (pow. tomaszowski, woj. łódzkie)
Framework element or context represented:
Marine sediments in the Tomaszów Syncline of the Szczecin-Łódź-Miechów Synclinorium, Central Poland.
Primary geological/geomorphological interest:
Stratigraphic profile with fossils.
Comparative assessment justification:
The only outcrop in Poland and one of a few in Europe presenting the Neocomian sequence of the Boreal Province.
Protection status and accessibility:
Abandoned and partly recultivated open pit, not protected, accessible.
Character of site: Abandoned open pit
Area: 1 ha
Altitude: 160-170 m a.s.l.
Lithology: conglomerates, breccias, limestones, sands, silts, clays
Discipline: Palaeobiology, Palaeoenvironment, Stratigraphy of Phanerozoic
Process Age: *all periods
Bedrock Age: Cretaceous, *all periods
Description of primary interest:
Condensed section of the Neocomian sediments cropped out in the clay-pit (now only short part of the sequence is exposed). The Lower Valanginian transgressive sequence (ca 3.5 m thick) lies over the Middle Volgian limestones and starts with thin layer of conglomerate composed of pebbles of Berriasian-lowermost Valanginian limestone (completely denuded during the early Valanginian break of sedimentation). The upper units represent: 1) fine-grained, clayey sands with oysters, brachiopods and microfauna, 2) brown clays and silts with ferruginous oolites, spheroidal or lenticular siderites, foraminifers and ostracods. Upper Valanginian sediments, more than 10 m thick were deposited after break of sedimentation embracing the Polyptichites zone and represent two transgressive sequences separated with gap in the Polytomus zone. They are composed of sandy-silty clays bearing ferruginous, mainly sideritic concretions, aggregates of pyrites and gypsum. The rocks contain remains of ammonites, lammellibranchs, gastropods, pelecypods, foraminifers, sclerites and ostracods. They are overlain by non-calcareous, varicoloured silts-sands without fossils. The paleofauna is typical for the Boreal Cretaceous Province, but occurrence of Tethyan ammonites in the Upper Valanginian suggests link with Tethys Basin. Study of microfauna recorded 51 species of ostracodes (21 new taxons) and 7 new species of holothurian sclerites. Ferruginous rocks of the Lower Valanginian were prospected as iron ores. Two types of mineralization were distinguished: 1) syngenetic ores – oolites of iron hydroxides formed in shallow marine environments, 2) diagenetic siderite concretions and blankets.
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