Dacian Basin, Eastern Serbia)
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GEOLOŠKI ANALI BALKANSKOGA POLUOSTRVA Volume 80 (2), December 2019, 13–37 – https://doi.org/10.2298/GABP1902013R Original scientific paper Facies analyses, biostratigraphy and Оригинални научни рад radiometric dating of the Lower–Middle Miocene succession near Zaječar (Dacian basin, eastern Serbia) 1 1 2 jUPKo UNDIć 1 EBojša aSIć 1 IoDRag aNj1EšEVIć L EjaN RRELEVIć , N 1IoLETa V ajIć , M ojaN oBSTIć , DELENa P TEfaNoV,I ćV g , B K & j S Abstract. Lower–Middle Miocene sedimentary succession and the conforma - ble/unconformable relationships between the lacustrine-continental systems (i.e. DLS, SLS) and Badenian marine transgression represents one of the in - trigue topics. Herein, we studied five exploration boreholes (eastern Serbia) and analyzed the main facies pattern, biostratigraphic characteristics of the Miocene succession, and applied the U-Pb radiometric dating of volcanic tuffs interstratified in the sedimentary series with coal layers (borehole NRKR- 17002 ). The obtained concordia age of 16.9 ±0.2 Ma for all the analysed zircon Key words: grains without any inherited cores indicate a single magmatic event. We defi - Lower–Middle Miocene, nite the freshwater series originated during Early Miocene Karpatian (= late lacustrine facies, Burdigalian). Consequently, for the first time, we demonstrate d that age of а marine transgression, part of the Serbian Lake System (SLS) is much older than it was previous re - U-Pb geochronology, ported. In addition, sporadic findings of foraminifers, ostracods and molluscs eastern Serbia. documented the late Badenian marine transgression in eastern Serbia. If ac - cept this fact the flooding occurred later than in the rest of Serbia (˂ 14.5 Ma). However, the lack of quality data and unclear stratigraphic position of some parts of the clastic succession (? Lower–Middle Badenian) makes this claim uncertain. Апстракт. Седиментна сукцесија између доњег и средњег миоцена и складан тј. дискордантан однос између језерско -континенталних наслага (нпр. DLS, SLS) и баденских морских седимената представља једну од занимљивих тема . У овом раду смо проучавали пет истражних бушотина (источна Србија) и анализирали главни фацијални образац, биострати - графске карактеристике миоценске сукцесије и применили U-Pb радио - метријско датирање вулканских туфова интерстратификованих у седиментној серији са слојевима угља (бушотина NRKR -17002). Доби je на је конкордија старост од 16,9 ± 0,2 милиона година за сва анализирана зрнца циркона без наследних језгара што говори да је у питању један магматски догађај. Прецизирали смо да је слатководна серија настала током раног миоцена – карпата (= млађи бурдигал). Сходно томе, по први пут смо показали да је старост једног дела Српског језерског система (SLS) много старија него што се раније мислило. Поред тога, спорадични 1 University of Belgrade, Faculty of Mining and Geology, Đušina 7, 11000 Belgrade, Serbia. E-mails: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected] 2 University of Belgrade, Technical Faculty in Bor, Vojske Jugoslavije 12, 19210 Bor, Serbia. E-mail: [email protected] 13 LJUPko RUnDić , n EBoJšA VASić , M ioDRAG BAnJEšEVić , D EJAn PRELEVić , V ioLETA GAJić , B oJAn koSTić & J ELEnA STEFAnoVić Кључне речи: наласци фораминифера, остракода и мекушаца документују касноба - Доњи –средњи миоцен, денску морску трансгресију у источној Србији . Ако прихватимо овај језерске фације, аргумент, онда се трансгресија догодила нешто касније него у остатку морска трансгресија , Србије (˂14.5 милиона година) . Међутим, недостатак квалитетних по - U-Pb геохронологија, датака и нејасан стратиграфски положај неких делова кластичне источна Србија . сукцесије (? доњи-средњи баден ) чини ову тврдњу доста несигурном . Introduction ESELINoVIć ETRoVIć V oPoVeIćt al., 1967o, P1o9V7Ić 5; P agIć , 1961T, E1V9aN6o9 , V1I9ć 88; P , 1968; P &a g NIć , 1969; aSRoVIć - The Dacian Basin was a paSrKta oRfE Vthe large Para - , 1958, 1964, 1967, 1977; g , 2005; M et tethyan epicontinental sea ( L , 1924). It cov - al., 2007 ). additionaly, in the area of Zaječar, the ers approximately the domain of the Moesian Miocene freshwater sediments with coal layers Platform located in the forealaSnILdIE oV f the highLlTyE baNeUnd - were determined more than a century ago and was eIdPa CarpathoI-PBa alkanLiadReIUs ( V , E2R 006oR; goH & exUpjolVoIić ted in thea ZDvoeVazNdoaVnIć coala mVLionVeI ć since 188IV9K o(eV.Igć . j , 2006; j & o , 2009; T B , 2013 ). ž , 1a8VL8o9V;I Rć & P , 1891; ž , During the Neogene, the area of eastern Serbia 1893; P , 1903). The scarce findings of bad (Timočka Krajina) belonged to the westernmost preserved freshwater mollusks, ostracods and parts part of the Dacian Basin which leaned on the Car - of fishes skeleton could not closely define the strati - pathian foothills and the southern branches of the graphic position of these deposits. Litostratigraphic Carpathiansa aRnoVdI ć further eastwaarNdIć to BulgarNiaEž aEnVId ć analyses and correlation with similar sediments of RomaaNnIć ia ( M ER et aolR.g, 1H 998; g , 2005; K the Intra-Carpathian basins indicated tohLeIć middle & g , 2013; T B , 2013 ). The sedimentary MTiEoVcaeNnoeVI ć age of that sediments (e.g. D , 1977; facies in the Dacian Basin indicate an overall regres - S , 1977). all previous studies were based sive pattern of complete basin fill, characterized by on the lithostratigraphic and biostratigraphic char - mass-progradation structures with near-shore fa - acteristics of the freshwater series. fossil endemism, cies, and large-scale deltaic environments observed lithostratigraphic similarity, unconformable/con - in particulaar NdIuć ring middaSleIL-IlEaV te MiocenIPea and LeaaRrIlU y formable relationship to the overl аyi ng rocks, lack of PlioceneE (R g oRg, H 2005; V , 20a0jI6ć ; j & o , marker beds, etc., were not enough to precisely date 2009; T B et al., 2014; Đ et al., 2018). theU NtDimIć ing of thUeN fDoIćrmation of these lake basins Based on the data from seismic sections and ex - (R , 2013; R et al., 2013, 2018). In addi - ploratory drillings, the total thickness of NeogenEeR tion, independent age analyzes such as radiometry roocRkgsH reaches up to a few thousand meters ( T or magnetostratigraphy have never been done. The B , 2013). In the area of eastern Serbia, the proposed model of the existence of a large lake sys - Miocene formations unconformably overlie the tem during the Miocene in tRhSTeI ć territory of Serbia lower Cretaceous (Valanginian to albian) sandstones (Serbian Lake System by K et al., 2003) has or upper Cretaceous (Cenomanian–Coniacian) car - opened numerous challenges of proving or doubting bonate and cElaSEsLtiINteo VroIć cks, andesite and theiorR vĐoEl VcIać n - the time span, distorLiIbć ution andU NgDeIćnesis of this laIrMgIeć ocalNajsEtšiEteVIsć ( V oReĐt EaVlI.,ć 1967, 1975N;T ĐoNIjEVIć & lake system (ea.NgT. D , 1998; R aNDIC et al., 2013; S B IjaToVIć , 1997; aĐSIć , 2005; a UNDIć & et al., 2017; S et al., 2018; M et al., 2019). M , 2014; V et al., 2018; R et al., In this regard, besides the main facies analysis 2018). In the framework of the Miocene succession, and biostratigraphic division of the Miocene succes - the middle Miocene Badenian marine deposits and sion, we applied the method of radiometric dating Sarmatian marine-brackish sediments have a great of volcanic tuff interstratified in the sedimentary se - 1d4 aisStKraibREuV tion. a lot of authžoorDsž orepooMrtIćed on that (e.g. ries, and tried to defineG emolo. arne. Bparlke. cpioslueolsy., t2h01e9 ,a 8g0e (2 o), f1 3t–h3e 7 L , 1924, 1934; D -T , 1963, 1970; Miocene freshwater series with coal as well as the Facies analyses, biostratigraphy and radiometric dating of the Lower–Middle Miocene succession near Zaječar (Dacian basin, eastern Serbia) timing of Badenian marine transgression in this part Balkanides orogen was enabled by the general oGfe Soerlobigai. cal background phase of uplifting manifested from the abReogVinIć ning of the Sarmatian to the recent time ( M et al., 2002, 2007). During the middle Miocene, the Pa - ratethys marine and brackish water was flooded area of the westernmost part ofN ĐCEaLrKpoaVtIćhian NfoĐrEeL - The area of eastern Serbia belongs to the Car - dKoeVeIpć in the territory of Serbia ( a & a - paETthKoV-IBć alkanNiDdjEeLsK oaVsI ć a large RteUcBtIćonic NuTnoiNt Ij(EeV.Igć . , 1997). It flooded different Mesozoic and P & a IMITRIjEV,I ć 1958 ; g RäUT&N EaR RSTIć , Tertiary arNoIcć ks dependaijnIć g on morphologUyN DoIfć paleo - 1961/19C6H2M; ID D , 1997; K & K , relief (g , 2005; Đ et al., 2018; R et al., 2003; S et al . 2008 and references therein). 2018). generally, different Mezosoic rocks (mostly according to the last mentioned authors , they alsIo Upper Cretaceous flysch, clastites, volcanoclastites MinIcTlRuIjdEeVI ćparts of the Serbo-Macedonian Massif ( D - and carbonates) as well as older Miocene continen - , 1997) and to the west, follow the eastern tal-lacustrine sediments represent the basement margin of East Vardar ophiolites. Inside this belt, rock for the mentioned transgressive sediments. the Timok fault represents one of the main strike- These Upper Cretaceous rock formations are known slip structure which displace the Cretaceous nappe aso RtĐhEeV Ić carriaeNrjsE šEoVfI ć mettalic orRaĐwEV Ić materialsN T(oeN.gI . unit along the contact betweCeHnM tIhD e Dacia Mega Unit ĐjEVIć &Ija BToVIć , 1997; Đ , 2005; a - and the Moesian