The role of biogenic silica in the formation of Upper Cretaceous pelagic carbonates and its palaeoecological implications

Jurkowska, Agata; Świerczewska-Gładysz, Ewa; Bąk, Marta; Kowalik, Szymon

doi:10.1016/j.cretres.2018.09.009

Cited by 31 publications

(56 citation statements)

References 77 publications

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“…The examined aragonite fragments of the shells were found in siliceous limestones with high porosity [19,20], which should have promoted rapid dissolution and the removal of the skeleton from the fossil record. For example, in British Cretaceous chalk the aragonite is “totally absent” [18].…”

Section: Discussionmentioning

confidence: 99%

“…Although the occurrence of aragonite fossils is quite common in Cenozoic deposits, the preservation potential of aragonite decreases with geological age (see [18]). The aragonite fossils of Mesozoic and (only exceptionally) Paleozoic age are only found when enclosed by argillaceous rocks or other impermeable deposits, so the highly porous siliceous limestones (opokas) typical of Upper Cretaceous deposits of central Europe (see [19,20]) are not considered a suitable environment for the preservation of pristine aragonite. To date, no fossils with preserved original aragonitic shells have been reported from these deposits; the formerly aragonitic shells typically occur as moulds (Fig 1A–1C; see also [21–23]) or entirely transformed (calcitized) specimens.…”

Section: Introductionmentioning

confidence: 99%

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From pristine aragonite to blocky calcite: Exceptional preservation and diagenesis of cephalopod nacre in porous Cretaceous limestones

et al. 2018

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Aragonite (along with calcite) is one of the most common polymorphs of the crystalline calcium carbonate that forms the skeletal structures of organisms, but it has relatively low preservation potential. Under ambient conditions and in the presence of water, aragonite transforms into calcite, the stable polymorph. Aragonite is also more soluble therefore, in water-permeable siliceous limestones (opokas) that are typical of Upper Cretaceous deposits of Poland and Ukraine, the primary aragonitic skeletons are either entirely dissolved and found as moulds and casts or transformed into secondary calcite, whereas the primary calcitic shells remain well preserved. Contrary to the common notion of the lack of aragonite in such porous carbonate deposits, we show that relics of aragonite can be preserved as a nacreous lining on cephalopod moulds or as thin, lenticular structures entrapped in neomorphic calcite. Based on the observed intermediate steps of aragonite alteration, we propose an extended model of nacre diagenesis. Among the originally aragonitic biota, only nautilids and ammonites have retained relics of pristine skeletons. Such selective preservation of only some aragonitic structures (nacre but not the prismatic aragonitic layers) points to the role of microstructural and biochemical differences between cephalopod shell layers that may set a threshold for the dissolution, dissolution/precipitation or preservation of original biomineral structures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

From pristine aragonite to blocky calcite: Exceptional preservation and diagenesis of cephalopod nacre in porous Cretaceous limestones

et al. 2018

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“…The name ‘opoka’ is widely used in Polish geological literature and refers to a specific variety of a siliceous limestone (see Jurkowska et al . 2019; Machalski & Malchyk 2019).…”

Section: Geological Settingmentioning

confidence: 99%

Correlation of shell and aptychus growth provides insights into the palaeobiology of a scaphitid ammonite

Machalski

2020

Palaeontology

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Scaphitids rank among the commonest and best‐known Late Cretaceous ammonites, yet many aspects of their palaeobiology are still unresolved. Here, natural moulds and co‐occurring aptychi (calcitic coverings of the lower jaw) of Hoploscaphites constrictus crassus from the upper Maastrichtian of Poland are studied. For the first time in a scaphitid ammonite, growth marks are identified on the moulds and aptychi, which enable a reconstruction of the successive ontogenetic stages of the shell and aptychus. These are correlated to each other, allowing us to address two open issues in scaphitid palaeobiology: (1) estimation of individual growth rate and age; and (2) assessment of the aptychus as a possible protective operculum. As far as the growth rate of H. c. crassus is concerned, this accelerated rapidly at the onset of the mature body chamber formation and decelerated shortly before the cessation of growth. The resultant growth curve departs significantly from the generalized growth curve previously proposed for ammonites. In contrast, an age of five years at maturity, tentatively estimated here for H. c. crassus, conforms to the previous estimates for shallow‐water ammonites of comparable size. The role of the aptychus as an operculum is rejected for H. c. crassus, based on a significant misfit in size and shape between the aperture and aptychus recorded during ontogeny. These conclusions may probably be extended to closely related members of the European Hoploscaphites constrictus evolutionary lineage and to some other scaphitids with shells similar in size and shape to that of H. c. crassus.

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“…Furthermore, relevant research offers important insights into the impact of silification on primary structural and textural features, allowing for a determination of the influence of sedimentology and diagenesis on properties of the rocks studied. The recognition of changes in the primary sediment matrix is significant as the history of diagenesis is studied [33][34][35][36].…”

Section: Geological Settingmentioning

confidence: 99%

Silification of the Mesozoic Rocks Accompanying the Bełchatów Lignite Deposit, Central Poland

Pękała

2020

Geosciences

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Fieldwork and exploratory study of Poland’s Bełchatów lignite deposit reveals that the Jurassic and Cretaceous sediments with overlying Neogene clays include rocks of greater hardness than the primary composition would indicate. Mineralogical and petrographic tests show the impact of secondary mineralization involving silification in particular. Transitional and carbonate rocks observed microscopically and subjected to X-ray examination show numerous polymorphic forms of silica replacing carbonate minerals. Opal types A and CT, chalcedony, quartz and microcrystalline quartz are all present. The process of silification observed is a selective and multistage one, with selective activity entailing the displacement and replacement of carbonates from older rocks, mainly Cretaceous opoka-rocks and marls, and Jurassic limestones. The opal fills tectonic fractures and has cemented cracked grains. Cathodoluminescence analysis identifies several generations of silica. The rocks have undergone advanced diagenesis as is evidenced by the recorded metasomatic reactions between minerals. They can further be assumed to be in the locomorphic stage. Such observations are relevant to efforts to reconstruct the origin of the rock matrix, and to the study of its textural features. In addition, the tests run on rocks of the lignite series would seem to be of significant value in identifying and developing associated rocks.

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The role of biogenic silica in the formation of Upper Cretaceous pelagic carbonates and its palaeoecological implications

Cited by 31 publications

References 77 publications

From pristine aragonite to blocky calcite: Exceptional preservation and diagenesis of cephalopod nacre in porous Cretaceous limestones

From pristine aragonite to blocky calcite: Exceptional preservation and diagenesis of cephalopod nacre in porous Cretaceous limestones

Correlation of shell and aptychus growth provides insights into the palaeobiology of a scaphitid ammonite

Silification of the Mesozoic Rocks Accompanying the Bełchatów Lignite Deposit, Central Poland

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