Sedimentologija gornje krede centralnog dela vardarske zone ⚒ Радови ⚒ Др РГФ

Ментор

Nebojša Vasić

Члан комисије

Dragan. Milovanović

Milica. Kašanin-Grubin

Креатор

Violeta M. Gajić

Датум издавања

2014-09-04

uri

http://eteze.bg.ac.rs/application/showtheses?thesesId=3240

https://fedorabg.bg.ac.rs/fedora/get/o:11624/bdef:Content/download

http://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=46627599

http://nardus.mpn.gov.rs/123456789/5848

Сажетак

Područje istraţivanja obuhvaćeno doktorskom disertacijom nalazi se ucentralnim delovima Vardarske zone. Karakteriše se sloţenom geološkomgrađom koju grade mezozojske tvorevine trijaske, jurske i kredne starosti, kao ikvartarni sedimenti. U trijasu je istraţivano područje pokrivalo more, sve dogranice sa Šumadijom. Tokom jure sloţenim geotektonskim procesima stvarajuse ofiolitske stene rasprostranjene u juţnim i delom u centralnim delovimaistraţivanog područja. U donjoj kredi se pokretima dinarske faze izdiglo kopno,koje je egzistiralo skoro u celoj donjoj kredi područja istraţivanja.U alb-cenomanu pojedini delovi istraţivanog područja se spuštaju i zahvata ihmorska transgresija. Dalja kompresija, tokom gornje krede, dovodi dotektonskih deformacija u ovom području i otvaranja basena u kojima se odvijalakarbonatna i karbonatno-terigena sedimentacija.Predmet istraţivanja ove doktorske disertacije predstavljaju sedimentne stenetaloţene tokom cele gornje krede i njihova evolucije kroz vreme i prostorcentralnog dela Vardarske zone. Rezultati dobijeni ispitivanjima petroloških,biostratigrafskih i genetskih karakteristika sedimentnih stena omogućila suraščlanjavanje gornje krede. Izdvojene su četiri litostratigrafske jedinice: 1.jedinica bazalnih gruboklastita, 2. jedinica šelfnih klastično-karbonatnih stena,3. jedinica krečnjaka i laporaca sa roţnacima kontinentalne padine i 4. jedinicaklastično-karbonatnih turbidita.Gornjokredne jedinice po svojim karakteristikama ukazuju na kontinuitet usedimentaciji, bez naglih promena u reţimu taloţenja. Na plitkovodni karakter basena najviše upućuje postepeni prelaz priobalskih, plitkovodnih (šelf) ibasenskih karbonatnih ili karbonatno-klastičnih stena (kontinentalna padina).Prvu izdvojenu jedinicu bazalnih stena čine najstarije sedimentne stene gornjekrede (alb-cenoman). Postoje dva tipa razvića bazalnih gruboklastita. Prvi tip semoţe definisati kao konglomerati i konglomeratični krečnjaci izgrađeni odvalutaka ofiolitskih stena, dok se konglomerati i konglomeratični krečnjacidrugog tipa razvića karakterišu fragmentima koji vode poreklo od karbonatnihstena.Nakon brze sedimentacije, usledila je mirnija faza koja je dovela do pojavekonglomerata sitnijeg zrna i konglomeratičnih krečnjaka sa proslojcimalaporaca i glinaca. Diferenciranjem morskog dna se pored dubljih morskihdelova, obrazuju i podvodni grebeni na kojima se razvijaju sprudne isubsprudne stene. Takvim tvorevinama odgovaraju analizirani crveni krečnjaciu Drenovcu.Tokom cenomana se kontinuirano na bazalne stene taloţe stene koje pripadajulitostratigrafskoj jedinici šelfnih sitnozrnih karbonatno-klastičnih stena.Izgrađena je od alevrolita, kalcitskih alevrolita, glinovitih alevrolita, peskovitihalevrolita i peskovito-glinovitih alevrolita. Oni čine postepene prelaze kakalcitskim peščarima, kalkarenitima i kalkruditima, koji predstavljaju završnufazu plitkovodnih facija i najvećim delom su erodovani. U sitnozrnimsedimentima Ješića i na Rajcu razvijena je breţuljkasta kosa slojevitost koja uvišim delovima prelazi u planarnu kosu slojevitost malih uglova. Ove teksturenastaju kada je taloţenje povezano sa olujama, a tokom mirnih vremenskihperioda sa plimatskim strujama.Na osnovu litoloških, biostratigrafskih i genetskih osobina dve najstarijegornjokredne izdvojene jedinice, one se moraju posmatrati kao celina. U vreme njihovog formiranja fizičko-hemijski uslovi sredine bili su promenljivi, što seodraţava kroz redosled taloţenja materijala.U gornjem turonu, usled dalje trangresije produbljavanja basena bilo je jošizraţenije. Sedimentacija se obavljala u basenu sa smanjenom energijom vode ipojavom pelaških organizama: radiolarija i foraminifera (Globotruncana), a odmakrofaune amonita i inoceramusa. Stvarale su se pelaške sedimentne stene,predstavljene laporcima, laporovitim krečnjacima, glinovitim krečnjacima ikrečnjacima, svi sa konkrecionim roţnacima. Jedinica krečnjaka i laporaca saroţnacima zauzima najveći prostor na ispitivanom terenu centralnog delaVardarske zone. Sedimentacija se odvijala na kontinentalnoj padini bez prekidado kraja mastrihta.Karbonatne stene mikritskog do biomikritskog sastava predstavljaju autohtonestene ove jedinice. U vreme visokog nivoa mora (trangresije) koja je dovodila dojaku eroziju obale, u basen se povremeno turbiditnim tokovima donosila velikakoličina materijala. Nastajale su turbiditne stene (grubljeg i finijeg zrna) koje suse smenjivale i mešale sa autohtone karbonatnim stenama basena. Prisustvoturbidita (kalkrudita i kalkarenita) sa karakterističnim teksturama iz Bouminesekvence potvrđuje povremeni prinos plitkovodnog materijala turbiditnimtokovima niz kontinentalnu padinu. Kao neodvojivi deo jedinice pojavljuju sekonkrecioni roţnaci, koji nastaju obaranjem silicije iz rastvora i metasomatskimzamenjivanjem karbonata u ljušturama fosila. Proces nastanka konkrecionihroţnaca objašnjava se niskim vrednostima pH i nepovoljnim uslovima zaopstajanje silicije u rastvorenom obliku.Gornjokredni basen u centralnom delu Vardarske zone, tokom senona, širio seka Šumadiji, dok je u njegovim zapadnim i jugozapadnim delovima došlo doizdizanja kopna. Tektonsko izdizanje planinskih masiva omogućilo je jačefizičko i hemijsko raspadanje stena i taloţenje debelih naslaga turbidita na krajukampana i u mastrihtu. Iz turbiditnih tokova preteţno klastičnog detritusa,nastalih iz više izvora sa šelfa i margine padine, taloţile su se stene u oblikuspojenih lepeza koje su formirale široku zonu u obliku zastornih turbidita(apron turbidite). Oni čine najmlađu izdvojenu litostratigrafsku jedinicu ugornjokrednim sedimentnim stenama područja istraţivanja. Najvećerasprostranjenje imaju pločasti sivi srednjozrni peščari bogati liskunima,alevroliti i ređe konglomerati, dok su u manjoj meri su zastupljeni laporci ikrečnjaci. Kampan-mastrihtski turbiditi na području istraţivanja deo su ljiškog išumadijskog fliša.

The research area covered by doctoral thesis is situated in the central part of theVardar zone. It is characterized by a complex geological structure built byMesozoic (Triassic, Jurassic and Cretaceous) and Quaternary sediments. DuringTriassic age investigated area was covered by sea to the Šumadija area bordereast. During the Jurassic complex geotectonic processes created ophiolitic rocks,widespreaded in the southern and partly in the central parts of the study area.In the Lower Cretaceous, tectonic movements of Dinar phase uplift themainland, and these conditions existed almost throughout the whole LowerCretaceous.In the Alb-Cenomanian, some parts of the study area were lowered and theybecame under the influence of sea transgression. Further compression duringthe Upper Cretaceous lead to tectonic deformation in this area causing basinopening, and sedimentation of carbonate and carbonate-terigenous began.Subject of this dissertation are sedimentary rocks deposited during the wholeUpper Cretaceous and their evolution through time in the central part of theVardar zone. Results obtained from petrologic investigation, biostratigraphicand genetic characteristics of sedimentary rocks allowed division of the UpperCretaceous. Four lithostratigraphic units are separated: 1. Unit of basalcoarsegrain clastites, 2. Unit of clastic-carbonate rocks from shelf, 3. Unit oflimestone and marl with cherts of the continental slope, and 4. Unit of clasticcarbonateturbidites.Upper Cretaceous units by their characteristics indicate continuity insedimentation, with no abrupt changes in the regime of deposition. Gradual transition of coastal, shallow-water (shelf) and basin carbonate or carbonateclasticrocks (continental slope) indicates shallow character of the basin. Thefirst determined unit was formed from basal sedimentary rocks of AlbCenomanianage with two distinct types of basal coarse-grain clastic rocks.The first type can be defined as conglomerate and conglomeratic limestonesmade of ophiolite pebbles, while conglomerates and conglomeratic limestone ofsecond type are characterized by fragments originating from carbonate rocks.After fast sedimentation, a calmer phase followed, which led to the occurrencesof conglomerates with smaller grains and conglomeratic limestones with layersof marl and shale. By differentiation of the sea bottom, close to the deeper partsof the sea, (submarine cliffs) reef and subreef rocks were formed. Suchformations correspond to analyzed red limestones in Drenovac quarry.During the Cenomanian age the lithostratigraphic unit of shelf with finegrainedcarbonate-clastic rocks was deposited continuously on basal rocks. Itconsists of siltstones, calcites siltstones, clayey siltstones, sandy siltstones andsandy-clayey siltstones. They make a gradual transition to calcite sandstones,calcarenite and calcrudites, which represents the final phase of shallow-waterfacies and they are mostly eroded. In fine-grained sediments on Ješić and Rajaclocality, hummocky cross bedding, which in upper parts are exceeding inplanar cross bedding with small angles are developed. This type of textureoccurs when the deposition is associated with storms or during the quietperiods with high tide currents.On the basis of lithological, biostratigraphic and genetic characteristics of thetwo oldest Cretaceous units, they must be considered as a one unit. At the timeof their forming, physical and chemical environmental conditions werevariable, which reflects the order of deposition. In the Upper Turonian, due to further transgression, deepening of the basin waseven more evident. Sedimentation was with reduced water energy andappearance of pelagic organisms: radiolarians, foraminifera (Globotruncana) andmacrofauna with ammonites and Inoceramus. Pelagic sedimentary rocks werecreated, represented by marls, marly limestones, clayey limestones andlimestones, all with concretion cherts. Unit with limestones and marls withcherts occupies the largest area in the central part of the investigated area of theVardar Zone. Sedimentation took place on the continental slope withoutinterruption until the end of Maastrichtian age.Carbonate rocks of micritic to biomicritic composition are autochthonous rocksof this unit. At the time of high sea level (transgression) which led to theoccasional strong coastal erosion, turbiditic flows brought large amounts ofmaterial in the basin. Turbiditic rocks, made of coarser and finer grains,alternated and mixed with the autochthonous carbonate rocks from the basin.Presence of the turbidites (calcrudites and limestones) with characteristictextures from Bouma sequence confirms the occasional bringing of shallowmaterial with turbiditic flows down the continental slope. Concretion chertsappear as an integral part of the unit, which were created by settling of silicafrom solution and metasomatic replacing of carbonates in the shells of fossils.The origin of concretion cherts is explained with low pH values andunfavorable conditions for the persistence silica in (solution) form.Upper Cretaceous basin in the central part of the Vardar Zone, during theSenonian age was spreading to Šumadija region, while, in its western andsouthwestern parts, mainland uplifting occurred. Tectonic uplift of mountainmassifs allowed stronger physical and chemical disintegration of rocks anddeposition of thick layers of turbidites at the end of the Campanian andMaastrichtian age. From turbidite flows, predominantly with clastic detritusformed from several shelf and margin slope sources, rocks were deposited inthe form of a merged fan, which further formed a wide zone of apron turbidites. They represent the youngest defined lithostratigraphic units in theUpper Cretaceous sedimentary rocks in the investigated area. The largestdistribution have flattened gray medium coarse sandstones, rich in mica,siltstones and rarely conglomerates, marls and limestones. CampanianMaastrichtianturbidites in the research area are the part of the Ljig andŠumadija flysh.

Vardar Zone, Lithostratigraphic Units, Upper Cretaceous,transgression, sedimentology, turbidites

Формат

application/pdf

Језик

sr

Издавач

Универзитет у Београду, Рударско-геолошки факултет

Права

Autorstvo-Nekomercijalno 3.0 Srbija (CC BY-NC 3.0)

Subject

Vardarska zona, gornja kreda, transgresija, litostratigrafskejedinice, sedimentologija, turbiditi

Тип

Докторска дисертација

Sedimentologija gornje krede centralnog dela vardarske zone

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