Slanic Tuff and associated Miocene evaporite deposits, Eastern Carpathians, Romania (original) (raw)
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Miocene Slănic Tuff, Eastern Carpathians, Romania, in the Context of Badenian Salinity Crisis
Geosciences, 2018
New geochronological investigations for the Slănic Formation, correlated with previous bio-and lithostratigaphical information, allow for a better succession of events for the Middle Miocene, including the absolute age of the Badenian salinity crisis in the bend sector of the Eastern Carpathians. Within the green Slănic Tuff, white tuff layers were in evidence. The main element distribution of the white and green tuffs indicates a dacitic composition, with higher SiO 2 content for the white tuff. The white tuff has a distinct mineralogical composition with quartz, plagioclase, biotite and clinoptilolite. From such a tuff layer a biotite concentrate gives a 40 Ar/ 39 Ar age of 13.7 ± 0.2 Ma. As above these tuff layers discrete levels of gypsum occur, the age documents the beginning of the restrictive circulation and formation of evaporites in this sector of Carpathians during Badenian times.
1998
In the middle Miocene Badenian evaporite basin of the Carpathian foreland basin, broad zones of sulphate deposits occur in the marginal parts, and narrow zones of chloride sediments are restricted to the basin center (Fig. 1). The origin of these evaporites is related to the salinity crisis at the end of Middle Badenian. The time and facies relations of evaporites occurring in marginal and central parts of the Carpathian foreland basin are still unc1ear and different correlation has been proposed for particular parts of the basin (Petrichenko et al., 1997). However, it is possible to correlate particular mar ker beds in both domains over a distance of hundreds of kilometers (e.g. Garlicki, 1994; Peryt et al., 1994, 1997) suggesting common controls of evaporite deposition regardless of the geological setting. In the lower part of the gypsum section in the peripheral part of the basin, a unit built of blocky crystalline intergrowths occurs (see photo on the front page of this issue). ...
Geologica Carpathica
Ore mineralisations from the Nízke Tatry Mts., assigned to a number of mineralisation stages, were dated in this work by U/Pb analysis by laser ablation-sector field-inductively coupled plasma-mass spectrometry (LA-SF-ICP-MS), Re/Os, chemical Th/U/total Pb isochron method (CHIME), and U-total Pb methods. The samples originated mostly from the large Dúbrava deposit, with additional samples from Magurka, Rišianka, Soviansko, and Malé Železné deposits and occurrences. Additional, mostly unpublished Re/Os, K/Ar, and Ar/Ar data are also considered and discussed. Uraninite from a granite pegmatite and molybdenite from quartz veinlets gave ages of 343±1 and ≈351 Ma, respectively, comparable to the ages of the host rocks. The previously published K/Ar datum on biotite from the scheelite stage (330±5 Ma) is interpreted as a cooling age and its relation to the ore mineralisation is not clear. The arsenopyritepyrite-gold stage was dated, although only at a single sample, to 320±8 Ma. The ages for the samples of the stibnitesphalerite-Pb-Sb-sulfosalts stage scatter also around this date, showing that these mineralisations are late Variscan. It could be assumed that this stage formed during the life span of a fluid circulation system and the later precipitation of stibnite and sulfosalts is simply owing to the temperature dependence of Sb solubility in the fluids. Scattered K/Ar data on illite document the Jurassic continental rifting but seem to be linked to none of the hydrothermal stages. The dolomitebaryte-tetrahedrite stage formed during the post-rift thermal relaxation of the Tatric basement, with ages varying between 156±13 and 128±4 Ma. The quartz-tourmaline stage, devoid of ore minerals, formed during the mid-Cretaceous Alpine metamorphism, with the scattered data averaging to ≈100 Ma. The following compression of the Tatric and Veporic complexes is reflected in sparse U/Pb carbonate ages (72 Ma) and remobilisation of uranium mineralisation (70 Ma). The constraints on the age of the quartz-Cu-sulfide and galena-sphalerite stages are insufficient but their formation could be perhaps placed into uppermost Cretaceous. The vein carbonates were remobilised at 17-31 Ma, with most ages clustering around 24 Ma, related to the burial of parts of the Tatric basement under the Central Carpathian Paleogene Basin. This work documents many episodes of Variscan and Alpine hydrothermal activity that can be linked to the tectonothermal evolution of the Western Carpathians.
Geological Quarterly, 2013
The Tomanová For ma tion, of Rhaetian age, over ly ing the Norian Carpathian Keuper in the Tatra Mts. is built of cy clic parasequences of mudstones and sand stones. Quartz (15 to 70 wt.%), kaolinite (13 to 46 wt.%) and 2:1 Al dioctahedral phyllosilicates (dioct 2:1: mus co vite, illite, illite/smectite: 5 to 39 wt.%) rep re sent the ma jor min eral phase. The kaolinite/dioct 2:1 ra tio de creases up wards in the sec tion (from 4.3 to 0.5) and sig nals vari abil ity in weath er ing/ero sion in ten sity and changing wa ter sa lin ity. Ma jor and trace el e ments (LILE, HSFS, REE) in di cate a uni form source-fel sic rocks lo cated prob a bly in the Vindelician High lands. The sed i men ta tion rate (83 mm/ky) was con trolled by cli mate. Al ter na tion of dry and hu mid pe riods is refered by sed i men tary tex tures and by ma tu rity of quartz (ae olian vs. flu vial grains), and or ganic mat ter con tent and com po si tion (C org and d 13 C org). Authigenic sid er ite or bethierine doc u ments wet and re duced con di tions in the up per part of the Tomanová For ma tion. The sedimention rate of the ma rine Dudzinec For ma tion at tained 25 mm/ka and the char ac ter of cy cles pre served in the se quence is sim i lar as that of the Tomanová For ma tion (fin ing up wards parasequences). How ever, the dif fer ent clay min er al ogy, the re cy cled char ac ter of the sil i cates, the dif fer ent d 13 C org and el e vated imput of car bon ate detri tus with spe cific C and O iso to pic pat terns doc u ment a dis con ti nu ity in the sec tion. The transgressive char ac ter of the Dudzinec Fm. was de duced from the strati graphic dis tri bu tion and en vi ron men tal char ac ter is tics of the ben thic foraminifera pres ent. Involutinids and spirillinids dom i nate in the lower part, endothyrinids gov ern the mid dle part, and in the up per part nodosariids and Ammodiscus-type micro fauna oc cur. These age-di ag nos tic microfossils in di cate a late Rhaetian age. Sea level rise in the Tatric Zone trig gered by ther mal ex pan sion of the Cen tral At lan tic Rift was grad ual, be ing af fected by in put of ter res trial clastic sed i ment both by fresh wa ter and by wind. The Tatric Tri as sic se quence in the West ern Carpathians helps un der stand ing of the de vel op ment of sed i men ta tion, palaeoclimate (kaolinite weath er ing), and palaeo ge ogra phy of the north ern most Tethyan Do main.
Studia Universitatis Babes-Bolyai, Geologia, 2003
The Transylvanides which represent the uppermost group of Alpine tectonic units of the Apuseni Mountains originated from a Mesozoic rift located between the Preapulian and Getic cratons (Rădulescu & Săndulescu, 1973; Săndulescu, 1984; Balintoni, 1997). The term "Foreapulian Block" ("Preapulian bloc" in Romanian translation), was used by Săndulescu (1994), for the continental mass from which the Northern Apusenides or Inner Dacides (the Codru and Biharia Nappe Systems) have been sheared. The name "Getic Craton" was proposed by Balintoni (1994a) for the continental fragment located between the Transylvanian Rift and the External Carpathian Flysch Basin, from which proceeded the Getic crystalline. The Transylvanides were emplaced antithetically, during the Austrian and Laramian orogenic phases. During the compressional (Early Cretaceous) period, the rift basin evolved towards a foreland retroarc type basin, because it was installed on the upper plate sheared margin. If the Austrian Transylvanides (ATS) and the Mediterranean Apusenides are described as "in-sequence" tectonic units, the Laramian Transylvanides (LTS) are "out of sequence". In the Apuseni Mountains tectonic context, the Austrian orogenic phase is considered intra-Albian or around the Aptian-Albian boundary, the Mediterranean one as intra-Turonian (pre-Gosau) and the Laramian one as intra-Maastrichtian and close to the Maastrichtian end. This fact complicates the recognition of the Transylvanides, as well as their description and classification. Balintoni (1994, 1997) proposed a dual classification of the Transylvanides, with particular names for the Austrian and Laramian ones, because some parts of the ATS can be found again within several units of the LTS. According to latter classification of this author, the ATS include the Izvoarele, Valea Muntelui, Feneş, Colţul Trascăului, Bedeleu, Ardeu, Căbeşti, Căpâlnaş-Techereu and Bejan nappes, and the LTS comprise the Groşi, Crilş-Bucium, Vulcan, Frasin, Metalliferous Mountains, Curechiu-Stănija and Mureş nappes. Besides this, the Laramian Transylvanides transported also the post-Austrian sedimentary covers. Regarding the ATS and LTS many unsolved questions still persist, as it is for instance: the precise age for pre-Austrian and post-Austrian sedimentary formations; the correlation between the Austrian tectonic units enclosed by the Laramian nappes; the number of the LTS; the amplitude of the tectonic displacement; the relation between the Apuseni Mountains and the South Carpathians; the opening age of the Transylvanian Rift; the development of the magmatic component of the Transylvanides; the initial locale for the sedimentary and magmatic formations. In the following we will analyse some actual issues of the relation between the ATS and the LTS and present an improved model. I. The Bucium Unit: fact or myth? The Bucium Unit was first described by Ianovici et al. (1976) as a part of the South Apuseni Mountains. These authors considered the South Apuseni Mountains as built up of some Early Cretaceous facial-structural units, arranged later by tectonic thrusting and folding, and they mentioned in the lowermost position, the Bucium Unit. According to them, the Early Cretaceous formations of the Bucium Unit are transgressively deposited upon the crystalline schists of the Highiş rise, which is formed by the Baia de Arieş and Muncel tectonic units. They are consisting of: micritic limestones, Tithonian-Neocomian in age; the Căbeşti Beds, Hauterivian-Aptian; the Valea Dosului Beds, Aptian; the Ponor Beds, Albian and the Pârâul Izvorului Beds, Late Albian-Cenomanian. In their upper part, the Pârâul Izvorului Beds grade into the Cenomanian Negrileasa conglomerates. The Pârâul Izvorului Beds unconformably overly the earlier formations, due to the Austrian orogenic movements. Bleahu et al. (1981) confirm that the sedimentary deposits of the Bucium Unit constitute the cover of the Baia de Arieş and Muncel nappes, yet they partially modify the lithostratigraphy of these deposits. Lupu (1983) considers the Bucium Unit as autochthonous, tectonically in a similar position as outlined by Bleahu et al. (1981).
Geologica Carpathica
In this study we present new 40 Ar/ 39 Ar age data obtained from volcaniclastic material intercalated within shallow-marine to neritic sediments of the Styrian part of the Miocene Paratethyan Sea, which allow a better control of the sedimentation. At Retznei quarry, a volcaniclastic layer has been deposited in erosional patches above a consolidated rhodolite limestone ("Leitha Limestone") of the siliciclastic/marine Badenian Weissenegg Formation. Ar-release plots of a biotite bulk-grain concentrate (30 grains) and a concentrate of three sanidine crystals (0.5-1 mm) display fairly flat release-patterns with minor fluctuation in the low-energy gas-release steps. From the statistical point of view the biotite concentrate yielded a high-precision plateau age of 14.21 ± 0.07 Ma, the three sanidine crystals yielded a plateau age of 14.39 ± 0.12 Ma. The radiometric ages obtained match the biostratigraphic record (Upper Lagenide Zone). A drill-core recovered from the well Hörmsdorf, exposes several sand-dominated horizons and two layers of crystal tuff, of the Karpatian Eibiswald Formation. Ar-analyses of one single biotite grain (> 1 mm) from the hanging-wall, another biotite single-grain from the lower tuff both display slightly disturbed Ar-release spectra. However Ar-plateau ages of 15.08 ± 0.09 Ma and 15.22 ± 0.17 Ma, respectively, have been obtained. Volcaniclastic rocks from Pöls are intercalated within the Florian Formation, for which previous authors suggested a Early Badenian age (16.4-ca. 15 Ma according to . A concentrate of two clear sanidine crystals (0.5-1.0 mm), yielded a perfect Ar-plateau recording an age of 15.75 ± 0.17 Ma, which is more precise than previously published K-Ar results.
Gypsum facies transitions in basin-marginal evaporites: middle Miocene (Badenian) of west Ukraine
Sedimentology, 2001
In the middle Miocene Badenian gypsum basin of the Carpathian Foredeep, west Ukraine, three main zones of gypsum development occur in the peripheral parts of the basin. Zone I consists entirely of stromatolitic gypsum formed in a nearshore zone. Zone II is located more basinward and is characterized by stromatolitic gypsum in the lower part of the section, overlain by a sabre gypsum unit. Zone III occurs in still more basinward areas and is characterized by giant gypsum intergrowths (or secondary nodular gypsum pseudomorphs of these) in the lowermost part, overlain by stromatolitic gypsum, sabre gypsum and then by clastic gypsum units. Correlation between these facies and zones has been achieved using lithological marker beds and surfaces. Of particular importance for correlation is a characteristic marker bed (usually 20±40 cm thick) of cryptocrystalline massive gypsum occurring in zones II and III. The marker was not distinguished in zone I, possibly because this bed is older than the entire gypsum section of that zone. These new results strongly suggest that the deposition of giant gypsum intergrowth facies and stromatolitic gypsum facies was coeval. In some sections of zones I and II, limestone intercalations have been recorded within the upper part of the gypsum sections. Considerable scatter of the d 18 O and d 13 C values of these limestones indicates variable diagenetic overprints of marine carbonates, but a marine provenance of the limestones is con®rmed by microfacies analysis. Some of the limestones are coeval with an intercalation of gypsarenitic, mostly laminated gypsum occurring in the sabre gypsum unit of zones II and III. Badenian gypsum formed in extremely shallowwater to subaerial environments on broad, very low relief areas of negligible brine depth, which could be affected by rapid transgressions. Stable isotope (d 34 S, d 18 O) studies of the gypsum demonstrate that the sulphate was of seawater origin or was derived from dissolution of Miocene marine evaporites. Investigations of individual inclusions in the gypsum indicate decreased water salinity when compared with modern marine-derived, calcium sulphate-saturated water. Groundwater in¯uences are indicated by high calcium sulphate contents of the brines in the evaporite basin. The chemical composition of Badenian waters was thus a mixture of relic sea water (depleted in NaCl), groundwater (enriched in calcium sulphate) and surface runoff .