Wyniki wyszukiwania - Biblioteka Nauki

1

Klimat i oceanografia przełomu jury i kredy zachodniej Tetydy

100%

Lodowski D. G.

Przegląd Geologiczny

|

2023

|

tom Vol. 71, nr 10

514--522

EN

The key aspect for evaluation of potential effects of ongoing environmental changes is identification of their controlson one hand, and understanding of their mutual relations on other. In this context, the best source of information about medium and long term coThe key aspect for evaluation of potential effects of ongoing environmental changes is identification of their controlson one hand, and understanding of their mutual relations on other. In this context, the best source of information about medium and long term consequences of various environmental processes is the geologic record. Numerous different-scale palaeoenvironmental events took place during the Jurassic/Cretaceous transition; amongst them, the best documented so far are: long term marine regression during the Tithonian-early Berriasian, climate aridization during the late Tithonian-early Berriasian, and tectonic activity in western parts of the Neo Tethys Ocean during the late Berriasian-Valanginian. This study, which is based on the Ph Ddissertation of Damian Gerard Lodowski, attempts to reconstruct the latest Jurassic-earliest Cretaceous paleoenvironment and its evolution in the area of the Western Tethys, with special attention paid to cause-and-effect relationships between climate changes, tectonic activity and oceanographic conditions (perturbations in marine circulation and bioproductivity). Here are presented the basic results of high-resolution geochemical investigations performed in the Transdanubian Range (Hárskút and Lókút, Hungary), High-Tatric (Giewont, Poland) and Lower Sub-Tatric (Pośrednie III, Poland) series, Pieniny Klippen Belt (Brodno and Snežnica, Slovakia; Velykyi Kamianets, Ukraine) and Western Balkan (Barlya, Bulgaria) sections. The sections were correlated and compared in terms ofpaleoredox conditions (authigenic U), accumulation of micronutrient-type element (Zn) and climate changes (chemical index of alteration, CIA), providinga consistent scenario of the Tithonian-Berriasian palaeoenvironment evolution in various western Tethyan basins. Amongst the first-order trends and events, characteristic of studied sections are the two intervals recording an oxygen deficient at the seafloor: 1) the upper Tithonian-lowermost Berriasian (OD I); and 2) at the lower/upper Berriasian transition (OD II). Noteworthy, this phenomena cooccurred with elevated accumulations of nutrient-type elements (i. e. enrichment factor of Zn). Besides, collected data document the late Tithonian-early Berriasian trend of climate aridization, as well as the late Berriasian humidification. Such record is explained by a model, in which decreasing intensity of atmospheric circulation during the late Tithonian-early Berriasian was directly connected with climate cooling and aridization. This process resulted in lesser efficiency of up- and/or downwelling currents, which induced sea water stratification, seafloor hypoxia and perturbations in the nutrient-shuttle process during the OD I. On the other hand, the OD II interval may correspond to tectonic reactivation in the Neo Tethyan Collision Belt. This process might have led to physical cutoff of Alpine Tethys basins from the Neo Tethyan circulation (both atmospheric and oceanic), driving the limited stratification in the former, and limiting the effect of gradual humidification of global climate (i.e. due to increasing strength of monsoons and monsoonal upwellings). nsequences of various environmental processes is the geologic record. Numerous different-scale palaeoenvironmental events took place during the Jurassic/Cretaceous transition; amongst them, the best documented so far are: long term marine regression during the Tithonian-early Berriasian, climate aridization during the late Tithonian-early Berriasian, and tectonic activity in western parts of the Neo Tethys Ocean during the late Berriasian-Valanginian. This study, which is based on the Ph Ddissertation of Damian Gerard Lodowski, attempts to reconstruct the latest Jurassic-earliest Cretaceous paleoenvironment and its evolution in the area of the Western Tethys, with special attention paid to cause-and-effect relationships between climate changes, tectonic activity and oceanographic conditions (perturbations in marine circulation and bioproductivity). Here are presented the basic results of high-resolution geochemical investigations performed in the Transdanubian Range (Hárskút and Lókút, Hungary), High-Tatric (Giewont, Poland) and Lower Sub-Tatric (Pośrednie III, Poland) series, Pieniny Klippen Belt (Brodno and Snežnica, Slovakia; Velykyi Kamianets, Ukraine) and Western Balkan (Barlya, Bulgaria) sections. The sections were correlated and compared in terms ofpaleoredox conditions (authigenic U), accumulation of micronutrient-type element (Zn) and climate changes (chemical index of alteration, CIA), providinga consistent scenario of the Tithonian-Berriasian palaeoenvironment evolution in various western Tethyan basins. Amongst the first-order trends and events, characteristic of studied sections are the two intervals recording an oxygen deficient at the seafloor: 1) the upper Tithonian-lowermost Berriasian (OD I); and 2) at the lower/upper Berriasian transition (OD II). Noteworthy, this phenomena cooccurred with elevated accumulations of nutrient-type elements (i. e. enrichment factor of Zn). Besides, collected data document the late Tithonian-early Berriasian trend of climate aridization, as well as the late Berriasian humidification. Such record is explained by a model, in which decreasing intensity of atmospheric circulation during the late Tithonian-early Berriasian was directly connected with climate cooling and aridization. This process resulted in lesser efficiency of up- and/or downwelling currents, which induced sea water stratification, seafloor hypoxia and perturbations in the nutrient-shuttle process during the OD I. On the other hand, the OD II interval may correspond to tectonic reactivation in the Neo Tethyan Collision Belt. This process might have led to physical cutoff of Alpine Tethys basins from the Neo Tethyan circulation (both atmospheric and oceanic), driving the limited stratification in the former, and limiting the effect of gradual humidification of global climate (i.e. due to increasing strength of monsoons and monsoonal upwellings).

2

Turonian-Coniacian (Upper Cretaceous) of the Babadag Basin (North Dobrogea, Romania) : integrated biostratigraphy and microfacies succession

51%

Lodowski D. G. , Walaszczyk I. P. , Grădinaru E.

Geological Quarterly

|

2019

|

tom Vol. 63, No. 1

39--64

EN

The Upper Turonian to Middle Coniacian (Upper Cretaceous) succession of the Babadag Basin (North Dobrogea, Romania) constitutes an apparently continuous fossiliferous carbonate succession. The presence of moderately rich inoceramid, ammonite and foraminiferal assemblages allows for the application of a precise biostratigraphic subdivision. The palaeoenvironmental conditions and evolution of the Babadag Basin during the Late Turonian-Middle Coniacian are inferred using microfacies analysis and foraminiferal spectra. Together, these suggest the Turonian-Coniacian Badabag Basin reflects relatively shallow-water conditions in a near-shore environment, punctuated by two regression events in the Late Turonian and in the Middle Coniacian.

3

The Jurassic–Cretaceous transition in the High-Tatric succession (Giewont Unit, Western Tatra Mts, Poland): integrated stratigraphy and microfacies

51%

Lodowski D. G. , Pszczółkowski A. , Wilamowski A. , Grabowski J.

Acta Geologica Polonica

|

2022

|

tom Vol. 72, no. 1

107--135

EN

Herein are presented the results of detailed bio - (calcareous dinocysts, calpionellids, foraminifers, saccocomids) and chemostratigraphic (δ13C) studies combined with high-resolution microfacies, rock magnetic and gamma-ray spectrometry (GRS) investigations performed on the upper Kimmeridgian-upper Valanginian carbonates of the Giewont succession (Tatricum, Giewont and Mały Giewont sections, Western Tatra Mountains, Poland). The interval studied covers the contact between the Raptawicka Turnia Limestone (RTL) Fm. and the Wysoka Turnia Limestone (WTL) Fm. Their sedimentary sequence is composed of micrites, pseudonodular limestones, cyanoid packstones, lithoclastic packstone and encrinites. A precise correlation with the previously published Mały Giewont section is ensured by biostratigraphy, rock magnetic and GRS logs. The methodology adopted has enabled the recognition of two stratigraphic discontinuities, approximated here as corresponding to the latest Tithonian-early (late?) Berriasian and the early Valanginian. The hiatuses are evidenced by biostratigraphic data and the microfacies succession as well as by perturbations in isotopic compositions and rock magnetic logs; they are thought to result from a conjunction of tectonic activity and eustatic changes. A modified lithostratigraphic scheme for the Giewont and the Osobita High-Tatric successions is proposed. The top of the RTL Fm. falls in the upper Tithonian, where cyanoid packstones disappear. At the base of the WTL Fm. a new Giewont Member is defined as consisting of a basal lithoclastic packstone and following encrinites.