Mineralogy and geochemistry of Mesozoic black shales and interbedded carbonates, southeastern Sicily: evaluation of diagenetic processes

1993 ◽  
Vol 130 (2) ◽  
pp. 191-202 ◽  
Author(s):  
E. Azzaro ◽  
A. Bellanca ◽  
R. Neri
Keyword(s):  
Lower Jurassic ◽  
Black Shales ◽  
Oil Fields ◽  
Isotopic Data ◽  
Pore Filling ◽  
Diagenetic Processes ◽  
Long Time ◽  
Oxygen Isotopic ◽  
Layer I ◽  
Original Organic Matter

AbstractUpper Triassic/Lower Jurassic organic-rich shales and interbedded carbonates (Rhaetian → Sinemurian) are widespread in the subsurface of southeastern Sicily where important oil fields have been found hosted in Triassic reservoirs. Core samples from wells drilled offshore and onshore were studied from petrographie and geochemical viewpoints.In the Hettangian/Sinemurian shale-carbonate sequences, which accumulated in a rapidly subsiding basin, the micritic aragonitic mud is still largely preserved. Mixed-layer I/S has remained randomly interstratified to a depth > 4000 m. Diagenetic carbonates are non-stoichiometric finely crystalline, pore-filling dolomite and/or calcite. The carbonate component exhibits a high Sr content and fair amounts of Fe and Mn. Carbon and oxygen isotopic values suggest a subsurface interstitial formation for the digenetic carbonates in an essentially closed system. Based on all accumulated data it is suggested that anoxic marine waters were retained in the sediment pores for a long time after deposition, thus enhancing the preservation of significant amounts of the original organic matter.In contrast, Rhaetian tidal-flat deposits hosting black shales display a clay component characterized by ordered illite-rich I/S and a carbonate mineralogy dominated by low-Mg calcite in the uppermost beds and by near-stoichiometric dolomite in the lowermost ones. Petrographie, chemical and isotopic data indicate early cementation in an oxidizing phreatic environment and lower down in the sequence pervasive dolomitization in a sabkha-type environment.

scholarly journals Trans-border (east Serbia/west Bulgaria) correlation of the Jurassic sediments: Main Jurassic paleogeographic units

2006 ◽  
pp. 13-17 ◽  
Author(s):  
Platon Tchoumatchenco ◽  
Dragoman Rabrenovic ◽  
Barbara Radulovic ◽  
Vladan Radulovic
Keyword(s):  
Shallow Water ◽  
Marine Sediments ◽  
Deep Water ◽  
Carbonate Platform ◽  
Lower Jurassic ◽  
Black Shales ◽  
Upper Kimmeridgian ◽  
Middle Callovian

In the region across the Serbian/Bulgarian state border, there are individualized 5 Jurassic paleogeographic units (from West to East): (1) the Thracian Massif Unit without Jurassic sediments; (2) the Luznica-Koniavo Unit - partially with Liassic in Grsten facies and with deep water Middle Callovian-Kimmeridgian (p. p) sediments of the type "ammonitico rosso", and Upper Kimmeridgian-Tithonian siliciclastics flysch; (3) The Getic Unit subdivided into two subunits - the Western Getic Sub-Uni - without Lower Jurassic sediments and the Eastern Getic Sub-Unit with Lower Jurassic continental and marine sediments, which are followed in both sub-units by carbonate platform limestones (type Stramberk); (4) the Infra (Sub)-Getic Unit - with relatively deep water Liassic and Dogger sediments (the Dogger of type "black shales with Bossitra alpine") and Middle Callovian-Tithonian of type "ammonitico rosso"; (5) the Danubian Unit - with shallow water Liassic, Dogger and Malm (Miroc-Vrska Cuka Zone, deep water Dogger and Malm (Donjomilanovacko-Novokoritska Zone).

scholarly journals Trans-border (south-east Serbia/west Bulgaria) correlations of the Jurassic sediments: Infra-Getic Unit

2006 ◽  
pp. 19-33 ◽  
Author(s):  
Platon Tchoumatchenco ◽  
Dragoman Rabrenovic ◽  
Barbara Radulovic ◽  
Vladan Radulovic
Keyword(s):  
Lower Jurassic ◽  
Geological Heritage ◽  
Black Shales ◽  
Point Of View ◽  
The West ◽  
Coal Beds ◽  
Lower Member ◽  
Upper Bajocian ◽  
Upper Boundary ◽  
Lower Bathonian

The Infra-Getic Unit is a palaeogeographic unit, predestined by palaeotectonics. From the point of view of geological heritage, it represents a geosites framework. For the purpose of the correlation, the Serbian sections of Lukanja, Bogorodica Monastery, Rosomac and Senokos, as well as the Bulgarian sections of Komshtitsa, Gintsi, and Stanyantsi were used. The Jurassic sediments of the Infra-Getic Unit crop out on the southern slops of the Stara Planina Mountain in east Serbia and west Bulgaria. The Lower Jurassic started with continental and continental-marine sediments (clays and sandstones) (Lukanja clastics and Lukanja coal beds in Serbia and the Tuden Formation in Bulgaria) and continue with Lukanja quartz sandstones (Serbia) and the Kostina Formation (Bulgaria). These sediments are covered by Lukanja brachiopod beds and Lukanja limestones (Serbia) and the Romanov Dol, Ravna and Dolni Loukovit Members of the Ozirovo Formation (Bulgaria) predominantly consist of bioclastic limestones. The sedimentations follow with Lukanja belemnites-gryphaea beds (marls and clayey limestones), which in Bulgaria correspond to the Bukorovtsi Member (also marls and clayey limestones) of the Ozirovo Formation. The Middle Jurassic sedimentation started with black shales with Bossitra alpine. These sediments are individualized in Serbia as Senokos aleurolites and clays and in Bulgaria they are known as the Etropole Formation. In Serbia the section continues with sandstones called Vodenicki sandstones of Bajocian age, known in Bulgaria as the Dobrogled Member of the Polaten Formation. However, in Bulgaria, the age is Upper Bajocian-Lower Bathonian, and it cover the marls of the lower member (Gornobelotintsi Member) of the Bov Formation and is covered by the upper member - alternation of marls and clayey limestones - the Verenitsa Member of the Bov Formation. The Vodenicki sandstones-Dobrogled Member which ended their distribution in the section of Komshtitsa, to the east (in the Gintsi section), they are not represented - build a body of sandstones, a prodelta coming from the west to the east. The Bov Formation corresponds to the Senokos ammonite beds in east Serbia. The upper boundary of the Senokos ammonite beds and of the Bov Formation is sharp. It is covered by grey limestones of the Yavorec Formation in Bulgaria and by the Kamenica limestones in eastern Serbia. They are covered by grey or red nodular/lithoclastic limestones ("ammonitico rosso" type) of the Gintsi Formation in Bulgaria and the Pokrovenik ammonitic (acanthicum) limestones in Serbia. The Jurassic section in the Infra-Getic ended with grey micritic and lithoclastic limestones, which belong to the Rosomac and Rsovci limestones in east Serbia and to the Glozhene Formation in Bulgaria.

scholarly journals New representations on oil and gas origin in connection with the opening of the phenomenon of reserves replenishment in exploited oil fields

Georesursy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 34-39
Author(s):  
Azariy A. Barenbaum
Keyword(s):  
Oil And Gas ◽  
Oil Fields ◽  
Main Role ◽  
Economic Activities ◽  
Gas Formation ◽  
Long Time ◽  
New Ideas ◽  
Origin Of Oil ◽  
Water Cycles

New ideas about the origin of oil and gas are discussed. They are caused by the discovery of the phenomenon of replenishment of oil and gas reserves in exploited fields. This phenomenon was discovered by the Russian geologists a quarter of a century ago, and a little later it was theoretically justified on the basis of the biosphere concept of oil and gas formation. As a result, the well-known «organic hypothesis» and «mineral hypothesis», which have long time competed in oil and gas geology are being replaced by new representations today, according to which oil and gas are the inexhaustible useful fossils of our planet. And their deposits are traps of movable carbon that circulates via the Earth’s surface in three main cycles with periods of ~108-109, ~106 -107 and ≈ 40 years. The 40-year carbon biosphere cycle, which was not previously taken into account at all, plays a main role in replenishment of deposits. Its accounting makes it possible to balance the carbon and water cycles in the biosphere, taking into account the economic activities of people and modern formation of oil and gas in the bowels, and also open up the possibility of exploiting deposits as constantly replenished sources of hydrocarbons.

Black shales and carbon isotopes in pelagic sediments from the Tethyan Lower Jurassic

Sedimentology ◽  
1986 ◽  
Vol 33 (1) ◽  
pp. 87-106 ◽  
Author(s):  
HUGH C. JENKYNS ◽  
CHRISTOPHER J. CLAYTON
Keyword(s):  
Carbon Isotopes ◽  
Lower Jurassic ◽  
Black Shales

Schistes lustrés from Corsica to Hungary : back to the original sediments and tentative dating of partly azoic metasediments

2003 ◽  
Vol 174 (3) ◽  
pp. 197-209 ◽  
Author(s):  
Marcel Lemoine
Keyword(s):  
Late Cretaceous ◽  
Deep Sea ◽  
Black Shales ◽  
Continental Margins ◽  
Long Time ◽  
The Alps ◽  
Mass Flow Deposits ◽  
Reliable Marker ◽  
Early Late

Abstract The Alpine and Corsican Schistes lustrés (SL) are nearly azoic Jurassic-Cretaceous metasediments often associated with ophiolites. They are derived from both the vanished Valais (N-Penninic) and Piemont-Ligurian (S-Penninic) oceans and from their continental margins. Their age is generally poorly known. Because of fossils discovered by Alb. Heim and by S. Franchi at the beginning of the 20th century, they were believed for a long time to be mostly Liassic in age. We know now that the major part of the SL is Cretaceous. Deep-sea sediments, and particularly the SL, are made up of a hemipelagic-pelagic background (HPB) associated with detrital components of local or distant origin. The nature of the HPB, mostly conditioned by Tethyan and worldwide events, is of great help as an at least rough stratigraphic marker ; in contrast, detrital material is not a reliable marker because it may occur at different times in different places. The HPB exhibits several successive, 10 to 40 m.y. long episodes which are either predominantly argillaceous (A) or calcareous (C). During the deposition of the Juras-sic-Cretaceous SL, seven episodes can be distinguished : C1, calcareous Liassic ; A1, marly Upper Liassic ; C2, calcareous latest Liassic and early Dogger ; A2, shaly or radiolaritic late Dogger-early Malm ; C3, calcareous late Malm ; A3 shaly or marly early Cretaceous ; C4 calcareous late Cretaceous. They can be recognized, each one by its prevailing lithology, and all together by their succession in order from C1 to C4. Nearly all of these subdivisions are here and there dated by rare fossils, which allow for a rough dating of the numerous azoic SL series. As they exhibit very different lithologies, from pelagic calcareous oozes to Black Shales and various kinds of flysch and other mass flow deposits, the SL cannot be considered as a specific, well-defined facies : they are not characteristic for a particular stage of the geodynamic evolution of the Alps. Finally, a possible influence of worldwide events is suggested. First, the role of the depth of the CCD, governed by early late Jurassic and early late Cretaceous biotic recoveries. Secondly, the correlation with first order eustatic events : transgressions on platforms seem to be roughly coeval with A episodes in the deep sea, regressions with C episodes.

Precipitation Source Inferred from Stable Isotopic Composition of Pleistocene Groundwater and Carbonate Deposits in the Western Desert of Egypt

1997 ◽  
Vol 48 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Mohamed Sultan ◽  
Neil Sturchio ◽  
Fekri A. Hassan ◽  
Mohamed Abdel Rahman Hamdan ◽  
Abdel Moneim Mahmood ◽  
...  
Keyword(s):  
Water Vapor ◽  
North Africa ◽  
Western Desert ◽  
Isotopic Data ◽  
Air Masses ◽  
Uranium Series ◽  
Nubian Aquifer ◽  
Stable Isotopic ◽  
Oxygen Isotopic ◽  
Carbonate Deposits

An Atlantic source of precipitation can be inferred from stable isotopic data (H and O) for fossil groundwaters and uranium-series-dated carbonate spring deposits from oases in the Western Desert of Egypt. In the context of available stable isotopic data for fossil groundwaters throughout North Africa, the observed isotopic depletions (δD −72 to −81‰; δ18O −10.6 to −11.5‰) of fossil (≥32,000 yr B.P.) groundwaters from the Nubian aquifer are best explained by progressive condensation of water vapor from paleowesterly wet oceanic air masses that traveled across North Africa and operated at least as far back as 450,000 yr before the present. The values of δ18O (17.1 to 25.9‰) for 45,000- to >450,000-yr-old tufas and vein-filling calcite deposits from the Kharga and Farafra Oases are consistent with deposition from groundwaters having oxygen isotopic compositions similar to those of fossil groundwaters sampled recently at these locations.

scholarly journals Supplemental Material: Oxygen isotope (d18O) trends measured from Ordovician conodont apatite using secondary ion mass spectrometry (SIMS): Implications for paleo-thermometry studies

2021 ◽  
Author(s):  
Cole T Edwards ◽  
et al.
Keyword(s):  
Mass Spectrometry ◽  
Oxygen Isotope ◽  
Secondary Ion Mass Spectrometry ◽  
Isotopic Data ◽  
Ion Mass Spectrometry ◽  
Oxygen Isotopic ◽  
Stable Oxygen ◽  
Secondary Ion

Table S1: Stable oxygen isotopic data of each conodont measured using SIMS; Table S2: Stable oxygen isotopic data using SIMS of the Durango apatite standard and a modern shark tooth; Figure S1: Cross plot of d18Omean values and OH/16O from the Shingle Pass (blue), Antelope Range (green), and Cincinnati Arch (white) sections.

Sign in / Sign up

Export Citation Format

Share Document