Depth geological relations of the wider area of Belgrade - based on the wells and geophysical data

. The subject work covers the Belgrade wider area with a total area of about 2,000 km2. The authors integrated the principal geological and geo­ physical data provided by surface works and multidisciplinary elements from the fifty-two wells with depths between 33 and 2733 m. Explicit paleontolo­ gical findings of specialized analytists with determinations of macro- and mi­ crofauna and flora are presented both from Neogene formations and the older basinal floor. In addition to conventional petrological descriptions of rocks, microscopic determinations of intrusive and extrusive magmatites were also cited. From the enclosed basin space, the mineralization of deep aquifers is also correlative positioned. From the geophysical data for wells deeper than 400 m, records of well logging measurements were used, with markers based on which valid stratigraphie delimitations were made. Seismic survey sections were the basis for spatial shaping of Neogene sedimentation and basin floor configuration. For in-depth geological interpretations, published and reposi­ tory gravimetric and geomagnetic maps of different sizes and years were con­ sulted. The authors focused primarily on factometric indicators without entering into variable and debatable theoretical schematizations, especially orogenically complex of subbasin tectonics, in dissonant relations with the younger disjunctive shaped configuration which is visually shown in the ref­ erence cross-sections both vertically and laterally.


Introduction
T he w id e r area o f th e city o f B elg rad e in clu d e s n o t o nly its cen tral and h ig h ly u rb a n p art, b u t also all th e p e rip h e ra l se ttle m e n ts th a t stretch a ro u n d th a t u rb a n core from b o th sid e o f th e Sava and D a n u b e riv e rs .W ith in th a t, so -ca lle d th e B e lg ra d e D a n u b e m e a n d e r (B e o g ra d sk i d u n a v sk i k lju č), in th e n a rro w e r sen se, m ean s th e area o f B elgrad e or  I (e.g. Pavlović, 1922;Luković, 1922;LASKAREvet al., 1931). A fter W orld W ar T h a n k s to g e o lo g ic a l-g e o p h y sic a l re se a rch as w ell as p e rfo rm e d e x p lo ra to ry d rillin g, it has lo n g b ee n kn o w n th a t p a le o re lie f or "old ro ck s" exp osed on th e su rfa ce o f th e te rra in so u th o f th e D an u b e River, b u ild the b asis fo r th e N eo ge n e an d Q u a te r n a ry se d im e n ts up to 4 0 0 0 m th ic k (e.g. P etković, 1951;A n đelko vić, 1960;M ar in o v ić, 197 0 , 1971N ikolić, 1976;M aksim ović et al., 1990;Pantić & D ulić, 1990;RADivojEVićet al., 2010;D unčić et al., 2017;D ulić et al., 2 01 9 ). H av in g all th is in m in d , as w ell as th e e x iste n ce o f cle a r d isc o rd a n t re la tio n s b etw ee n stratigrap h ie u n its and , in th a t sen se, sig n ific a n t stra tigra p h ie d e v ia tio n s in a sm a lle r area (local u n c o n fo r m itie s , e ro sio n s, p ro n o u n ce d d is ju n ctiv e te cto n ics, etc.), the p rese n ta tio n o f o u r re su lts w ill co n trib u te to a b e tte r u n d e rs ta n d in g o f th ese p rocesses. data and th eir further approximation, a huge database of geological docum ents (prim arily stratigraphic-paleontological, structural and vvell-logging data), was the key motive for presenting these results to the wider professional and scientific public. Having in mind that the studied area in the northern part is com pletely covered w ith Q uaternary sedim ents, the paper especially emphasizes specific and original in terp retations of the distribution and depthrelationship of main stratigraphic units as well as th eir m orphostructural features.

Material and methods
The presentation of the depth geological structure of the Belgrade w ider area is the result of the analysis of 15 deep wells on the Banat side of the Danube river (Fig. 1). In the southern part of studied area 37 m ostly shallow w ells w ere analyzed. It should be noted th at in the given scale o f the graphics (Figs. 1 and 1 0 ), n ot all th e toponym s m entioned in the text nor shallow vvells could be shown.
The com plete list o f used wells can be found in the Table l.T h e collected stratigraphic- Bilibajkić, 1 9 9 8 ). In addition, geom agnetic maps Az anom alies ZMP 1 9 5 4 (Nikolić & Simin, 1 9 5 9 ) and the fund o f th e Za in tensity section w ere used, except for the areas th at w ere deleted from the com petent authorities in due tim e.
Based on all of this, the first signed author constructed subsurface geological sections of the SW Banat (profiles I, II and III) as well as the map of Neogene base configuration(E = 1 0 0 m), which covers an area of about 2 ,0 0 0 km2. The depth geological model defined in this way is supplemented with facts that refer to the subsurface and outcrop geological data of the wider area of Belgrade, that is south ofth e Danube river (LjR).

Pre-Tertiary basement
In the studied area, the pre-Tertiary bassem ent m akes the geological and stratigraphic units of Jurassic and Cretaceous age of different genesis.

Jurassic
The oldest Jurassic unit is a series of dark to black tectonized clays and argiloshists w ith sandsiltstone intercalations perm eated by quartz grains. It was found in the well Pč-1 (2 ,3 9 5 -2 ,7 3 3 m) and can be correlated with sim ilar deposits in the close vicinity, i.e. w ith black sericitized claystones with sandstone in serts found in the well Crepaja-1 (1 ,5 9 7 -1 ,6 0 3 m) then, generally, with "shiny shales" ( P a n t i ć , 1 9 7 8 ), as well as w ith black sericitized thiny-bedded claystones, siltstones and sandstones of the well Padina-1 (1 ,5 5 4 .3 -1 ,6 1 3 .6 m). Based on the analysis of the palinospectrum (insight into the original report dated 2 8 .0 6 .1 9 5 8 by N. Balteš Claystones and clayey siltstones with the association of dinoflagellate algae (N a n n o cera to p sis cf. g r a c ilis A l b e r t i i G on yau Iacista sp.), spores and pollen of the type G in kgoales spv C ycadophytes sp., K on kisporites sp.), w ere drilled in the BNsj-1 well at a depth of 1 9 0 1 -1 9 0 8 m (Fig. 6). Stratigraphically, th ese deposits correspond to the upper Lias (Jx) (Č a n o v ić & K e m e n ci, 1 9 8 8 ; P a n t i ć & D u lić , 19 9 0 ).
On the other side of the Danube River, in the well G-1 (Grocka), in adepth interval from 1,300 to 1,378 m, the pelites w ith an abundance of radiolarians (M irifusus m ed io d ila ta tu s ( R u s t ) and P avicin gu la b o e s i ( P a r o n a ) , less often with spores and other palynomorphs w ere drilled (Š . Goričan, in K n e ž e v ić et al., 1 9 9 4 ). Relatively recently, from dark red radiolarites from a depth of 13 7 8 m, the next radiolarians w ere identified: B ellez a d e c o r a ( R U s t ), Sem ihsuum sp. A, P raew illiriedelu m robustum (M a t s u o k a ) , Mirifu su s d ia n a e s.l. ( K a r r e r ) , S p on g ocap su la p a lm e r a e P e s s a g n o w hich corresponding to the latem iddle Jurassic, while from a depth of 1,400 m the younger Jurassic association of radiolarians was determined: P a r a p o d o c a p s a a m p h itr e p te r a ( F o r e m a n ) , Cinguloturris c a r p a tic a D u m jt r ic a , E u cyrtidiellu m ptyctum ( R i e d e l & S a n f ilip p o ) , A rch aeo d icty om itra m in oen sis ( M iz u t a n i ) , P rotu n u m a ja p o n ic u s M a t s u o k a & Y ao , Z ham oidellum ovum D u m itr ic a , H iscocapsa h ex ag on a ( H o r i ) . Biostratigraphically, it corresponds to the Upper Jurassic (J3-middle Oxfordian to late Tithonian) ( Đ e r i ć e tal., 2 0 1 0 ) (Fig. 6).
The com plex of ultrabasic rocks (a ) is represented by peridotites and serpentinized peridotites  . They w ere found in the w ells Gl-1 (below 8 6 5 m) and Gl-2 (below 8 3 5 m) in the north ofth e studied area where they form the Pre-Tertiary basem ent. Som ew hat further to south, in the Ov-1 well, com pact peridotites at the bottom of the well and cracked serpentinites at higher levels w ere drilled in the interval 4 2 4 -4 5 4 ,4 6 m (Figs. 2, 3). They belong to the m asif of peridotite-pyroxene rocks. Morphologically, the top of the buried m agm atite is located in the narrow est area of Ovča, and its the longitudinal depth root m ost probably in the belt of the main tectonic fault, in the area betw een the Sibnica and Tamiš rivers (Fig.3). An ultramafic complex was identified in the SA-2 well, betw een 3 5 2 and 531.5 m (K n e ž e v ić etal., 2018a). Peridotites and serpentinized peridotites are degraded, tecton ic deformed and intersected by a netw ork of cracks. They are hydrotherm ally altered (Fig. 3).

Cretaceous
The coarse clastite complex (KB) lying over the ultramafic rocks was discovered in the wells Ov-1 and SA-2. It is built of hard breccias, or conglo-breccias. The clasts originate mainly from ultramafites, predominantly angular pieces of seprentinized peridotites ( Fig. 3) tightly bound by cem ent that partially contains a high percentage of carbonates. The thickness of these breccias is from 94m in the well Ov-1 ( 3 3 0 -4 2 4 m] to over 120 m (2 2 9 -3 5 2 m] in the well SA-2 ( Fig. 5]. In the Ov-1 well, this complex is covered by the tectonized flysch sediments. On the Belgrade side, similar the com pact serpentine breccias w ere discovered in well Bt 1-2 (Ljubičica-Leštane) where, in the interval of 28-38 m depth, they overlie the mass of serpentinized peridotites in which drilling was completed (92m ) (R u n d ić et al., 2019).

Structural-paleogeographic interpretation
The stru ctu ral-tecto n ic in terp retatio n o f prim a-  (Fig. 1 0 ), th eir ou ter con tou rs w ith m inor Depth geological relations ofthe wider area of Belgrade -based on the wells and geophysical data ch an ges -as far as th e size o f th e m ap allovved, are ap p ro x im ately fram ed a cco rd in g to th e reg io n al m ap by Milovanović & Ć i r i ć (1 9 6 8 ) .
In order to emphasize the im portant depth structural configuration, the map avoids plotting literarynum erous variants (m ostly assum ed) of m utually inconsistent faults of different conceptions, names, directions and mutual relations. The routes of the reference m entioned faults fit in organized directions of denser, relatively sh ort curved uniform equidistant distances. The large fault system s are recognizable by distinctly condensed isopaches of the main fractured directions, in principle, an overall disjunctively shaped neotectonic structures.
Taking into account all the above-m entioned, th ree main structural units w ere separated in the investigated area: Belgrad e-Banat M orphostructural Ridge (BBMR), Pančevo-Danube Neogene Depression (PDND) and the W est Banat Neogene Belt with the edge of regional the Srem depression (WBNB).
The Belgrade-Banat m orphostructural ridge (BBMR), in this article, is defined by the eastern side from Crepaja in the north, the low er course of the Tamiš river and the Danube riverbed to Ritopek, and then across Vrčin further to the south. The western border is marked by a fragmented rim of regional the Srem Neogene depression, which continues from M oštanica, Surčin and the Zemun polje, through Kovilovo on the Banat side, to the northeast, encompassing the Jabuka and Glogonj m assifs ( Figure 10, central part of the map).
In the central part of BBMR, the geomagnetic impact is m ost pronounced along the axis: Horst-massif Glogonj-Velika hum ka-Jabučki rit-Railway station of Ovča-M irjevo-M ali Mokri Lug-Ljubičica-Zuce and fu rth er to Kasapovac. The specified route determ ines the belt of pre-Cretaceous penetration of ultrabasic m agmatites o fth e Cimmerian tectogenesis, graphically shown as a subbasin projection on the reference map of the Neogene base configuration (Fig. 10). In the m eander of the Zavojnička river, near Zuce, as well as east of Avala Mt. to the south, serpentinized peridotites on the surface are in a reverse w est-vergent relation to the Cretaceous deposits they cover (Marković, 1 9 8 5 ). From the closed maximum geom agnetic anom aly of Zuce, through Jajinci to Kanarevo brdo, the rectilinear lineam ent to the south d ecreases sharply, and som ew hat milder in the parallel direction Banjica-Senjak, with the tran sverse segm ent Kanarevo b rd o -B an jica (Belgrade center). These points to the routes of com pensatory-connected the depth faults of Dinarides orientation with a droped southw est wing.
To understanding the area of Avala Mt., in the shortest form, it is necessary to com bine two mutually com plem entary geological-geophysical approaches. The first one is th at the dom e-shape formed Avala Mt. (al. 5 1 1 ), built of tectonized terrigenous flysch, including the low est w estern and southern periclines, is marked by an anomalous geom agnetic m inimum of a closed oval-funnel configuration, which indicates a depth absence of ultram afic massive. A nother approach is to slightly decrease the gravim etric values, generally a parallel orientation, south of the center of the Beli Potok Neogene trench and the previously m entioned Zuce, including at the m orphologically dom inant m assif of Avala Mt. It m eans th at below itscap built of flysch sedim ents there is no petrologically indeterm inate m agmatic pluton, or an ultram afic rock of older Alpine magm atite of m eridional orientation. Contrary, it is an oval-transverse intrusive occurence (acceptable literary as a lacolite) in principle of acidic com position, certainly from younger tecton ic stage. It corresponds to granite-granodiorite, or sim ilar m agmatic differentiations. This is supported by the once established occurrences of post-C retaceous penetration of neutral or neutral-acid apophyses, w ires and phylonites, both atthe Avala Mt. m assif itself and in the surrounding wider area, partly with a contact changes, or even later hydrotherm al mineralization in Šuplja stena and Džever kam en (Gudović, 1 8 75; Dimitrijević, 1 9 31; Stevanović, 1977).
A positive gravim etric anomaly of the E-NE direction is expressed from the elbow of Zavojnica river. On surface in the area of Boleč m ehana and Babin vis, the opposite inclinations of Sarm atian sedim ents are noticeable, which is indicative of the existence of a deep vault that sinks around Ritopek towards Ivanovo in Banat.
South of the great m eander of Danube river, a gravim etric anomaly of a closed oval configuration stands out, w ith a m axim um in crem ent below Slanci. However, the geom agnetic influence from Mirjevo, i.e. the axis of the deep fault to the east, is in a trend of continuous decrease, indicative of the deficit of ultrabasic masses, within the not deeply sunken, an ob]ectively turbidite and Cretaceous flysch subbasin structure. On the northeastern wing of the m orphostructure, within the well V-150, the basin bedrock was not reached to a depth of 194 m, nor was the deepest well up to 219 m in that area (D o lić , 1997). According to the constructed map here, it would be on a vault at a depth of about 200 m.
The presence of depth igneous channels from the basin floor of high convective heat transfer and intrabasin frequent the older Miocene effusive breakthroughs is shown on the map of geothermal gradients with closed anomaly 0,09 °C/m which is 40% larger than the area with the sunken Neogene sedimentary column with a dominantly conductive heat transfer on the eastern Banat side (M a rin o v ić , 20 1 9 ). In this area, thanks to frequently volcanogenic deposits within the Pre-Badenian continentallacustrine series, the structural-tectonic elements originally adapted to the floor morphology, were altered by accompanying extrusions and additionally disturbed by a complex system of the parquet faults towards structural reorientations in the all directions. In that way, the intertwining of the primary structural fabric, the discordant sedim entary column disturbed by renewed extrusions (clasts, white and gray tuffs), was achieved, with possible synsedimentary pleats of lower intensity. Pre-Badenian antiform complex with its discordant Badenian cover, along the stepped fault gradually sinks into the Pančevo depression, and through Mirjevo it is connected to the Belgrade structural units by a shallow saddle (Fig. 10).
The Mokri lug Neogene subdepression is disjunctively formed within the contour of Zvezdara south-Šum ice-M arinkova bara-M iloševac-Jajinci-Razbojište-Kumodraž-Kaluđerica (generally, southeast from Belgrade center, Fig. 10). On the basis of combined geological columns from the surface and from wells (S te v a n o v ić , 1977; Spajić, 1987) very variable thicknesses of stratigraphic members were interpreted in ranges: pre-Badenian 5 0 -3 5 0 m, discordantly Badenian 1  To the north of the discovered tectonized Mesozoic massifs of the Belgrade hills, below the morphologically disparate urban area, the Badenian shallow-water ridge of Čubura-Tašmajdan-Kalemegdan (Belgrade center) point up, with its especially southern extensions. In that area, in some places with discordantly arranged remains of clastic basal m olasses, during the pre-Pontian overflowoutflow episodes, the various sections of the thinned, originally more complete sedimentary column were partially or completely eroded. This refers to the entire area of the flange-separated paleorelief of complex geometry, where the cover built of the Neogene sediments are generally less than 100 m thick, i.e. there are wedge-shaped, lenticular and very thin layers which was noticed by several authors (e.g.  Finally, south of the Upper Cretaceous-Paleogene Ostružnica flysch horst-m assif of orogenic meridian tectonics, a Neogene structural trench was formed, in the NW-SE direction, which has a depth of about 700 m between Umka and M. Moštanica and the extrem e Miocene paleogeographic rim towards Sremčica (the extreme SW part of map).
The Pančevo-Danube Neogene Depression (PDND) extends east of the described BBMG. In that area, the largest morphostructural unit is the Pančevo Neogene depression (Fig. 10, central and NE part). It has oval contours of 20x15 kilometers, with a bottom of about 2,600 m. The outer contour is somewhat elongated from Kačarevo to the north towards Crepaja, and to the south it has a trend of turning towards Bavanište. The western boundary is marked by a complex Neogene fault system, which connects from Crepaja to the eastern flank of the Jabuka horst m assif to the already described the large longitudinal fault of the eastern BBMG boundary. On its SW side, the depression is characterized by the inner half-trench bay of Starčevo. The eastern boundary of the depression was determined by the m orphostructural series of the sub-basin horstmassifs Banatsko Novo Selo-Dolovo west-Bavanište NW (Bav-1, Fig. 6). In the south, it is bordered by the Omoljica horst-massif.
The Neogene bedrock in central part of the depression is formed by tectonized, early Jurassic, darkto blackpelites (sericite clays) (below 2,395 m in the well Pč-1), thicker than the drilled 338 m, without the presence of ultrabasic magmatites with determined direction towards Crepaja (Cp-1,1,597 m). Along the length of the western and eastern sides, they are building a sub-basin basis predominantly of tectonized the Lower Cretaceous deposits with penetrations or synsedimentary basic magmatites and superpositionally limited the Upper Cretaceous flysch (Bav-1, Fig. 6). The Neogene depression in Pančevo should not be equated with the eastern trench of depression Dolovo selo-Skorenovac-Smederevo (further east, outside the map outlines), which is, with its NW segment to the interdepression threshold Dolovo w est-Bavanište northw est (Bav-1) included in the constructed map.
These oldest Neogene sediments in the center of the depression are about 550 m thick. They were formed in extrem ely reduced, subaquatic conditions, which is especially emphasized in this paper due to significant differences in relation to heterogeneous, a predominant oxidative m olasse of the surrounding areas.Badenian m arine sediments, with the largest thickness up to 600 m, completely cover the reducing bottom m olasses within the deepest sunken parts of the depression. On the sides of the depression, including the belt of the interdepression threshold (Bav-1, Doz-1, BNs-1), they heterogeneously lie directly above the sub-basin tectonized floor, but not covering the peripheral peaks of Omoljica, Jabuka and Banatsko Novo Selo. Marine-brackish Sarmatian, of generally transgressive continuity, east of the Jabuka horst m assif abruptly thickens to the center of the depression (about 500 m), significantly covering the Omoljica horst, and sparsely (about 60 m) the extreme NE peripheral plateau of Banatsko Novo Selo (BNs-1).
The lacustrine, mostly marly caspibrackish Pannonian-Pontian sediments, together of the greatest thickness (more than 900 m), are generally directed to centre with a pronounced trend of thinning towards the western edges of the depression, and in the zone with stepped faults, with complete extinction of the Pontian complex. The Neogene oxidation m olasses of uncertain contours near Grocka up to 2 0 0 m thick (K n e ž e v ić et al., 1 9 9 4 ), are covered bydiscordantly younger, the m arine Badenian sedim ents, vvhich thinnen along the SW rim and surrounding horst structures. The m arine-brackish Sarm atian from the deeper sunken NE sides, thickens inversely to the SW and S, more than 3 0 0 m and tog eth er w ith the caspibrackish Pannonian sediments up to 700 m. The marginal facies ofthe Pontian on the SW flanks ofthe subdepression wedged out from Grocka towards Zaklopača, and from Brestovik near the Danube river towards Begaljica, and significantly thicken on the NE extension of the subdepression trench from Banatski Brestovac to Bavanište. The relatively thin Quaternary cover has not been specifically studied.
During the Neogene tectonics, two depressions w ere formed on the northw estern side of BBMG: Sefkerin depression, w est of the Tamiš river and the Batajnica depression, partly on the extrem e SW part of the Banat Danube course and partly on the Srem side of the Danube course around Batajn ica (NW part of the map).
The Sefkerin depression stretches from Opovo in the NW and Jabučki rit in the SE, about 25 kilom eters long and about 10 km wide, w ith a maximum depth of about 1,900 m. Betw een the Jabuka horst and the NW flank of the Ovča massif, it is connected to the Pančevo depression by a structural saddle, and in the area of Besni fok-Padinska skela there is a w ider com m unication with the Batajnica depression (Fig. 10). The basin bedrock along the NE flank of the depression is built by the already considered u ltrabasites w ith a cover built of the Lower Cretaceous clastites. Under the central part of the depression, the tectonized Cretaceous flysch is prognostically represented. Based on increased geom agnetic influences, especially tow ards the Belegiš horst, younger Lower Cretaceous complexes are indicative, possibly with the iron-glauconite clastites.
In this area, the older M iocene sedim ents are sm aller in thickness com pared to the Pančevo depression, but with an increased clay-marl complex, especially w ithin the Pannonian-Pontian time, and an increased thickness of sandy-clay of Pliocene deposits. Above the interdepression horst m assifs of Jabuka and Glogonj, as the mentioned before, the invasive overflow was achieved at the begining of Pannonian. From the Vrbovsko towards the top of the Belegiš horst on the Srem side, the total thickness of Neogene sedim ents decreases to about 1,100 m. The structural threshold towards the NE part of the Batajnica depression was interpreted at a depth of 1,500 m (the extrem e NW part of the map).
The Betw een Padinska Skela and the eastern periclinal of the Belegiš m orphostructure, the depression is structurally associated with the Sefkerin depression. W est of Novi Banovci, the peripheral parts of the depression are shallow er and m ore com plex depth configurations. The uncovered area towards Nova Pazova is gradually shifting to a parallel lineam ent, the beginning of which is visible in the NW within the map, with depth-geological relations that are outside the studied topic.

Discussion
The w ider Belgrade area has been the subject of geological studies for m ore than a century. In that sense, the earlier authors, each in th eir own way, contributed to the knowledge of the geological characteristics o fth is area. However, the im pression rem ains that these are m ostly segm ented works that dealt w ith individual aspects of stru ctu ral-stratigraphic relations and possible relations of Miocene deposits tow ards the older rocks (e.g. P a v lo v ić , 1922; L uković, 19 2 2 ; N ik o lić , 1976; S te v a n o v ić , 1977; D o lić , 1997). In Belgrade and its surroundings, ith as been knovvn for a long tim e th at the Jurassic-C reta- At the beginning, without pretending to talk more about the affiliation of rock deposits from the basin bedrock to certain large tectonic units (see M la d e n o v ić , 1 9 9 1 ; D u n č ić et al., 2 0 1 7 ; T o l ji ć et al., 2 0 1 8 , 2 0 1 9 ) because we dealt more with the rocks filling the basin, we note that based on the depth dem arcations and the mutual relationship between the units, we were able to quite accurately locate the depth, subsurface routeof the ultramafic distribution in this area(a north-south dashed line, Fig.   1 0 ). In this work, it isfully factom etrically documented and has a clear subsurface extension in the direction plotted on the map (Glogonj-Velika humka-Jabučki rit-railway station of Ovča-Mirjevo-Mali Mokri Lug-Ljubičica-Zuce and further along to Šuplja Stena-Kasapovac). This route within the Banat sub-basin belt up to 10 km wide apically determines the main depth distribution of intrusive ultrabasic magmatites, whose root follows the geomagnetic deficit of the eastern edge of the belt and as such is, for the first time, clearly marked and graphically shown on geological cross-sections I and II (Figs. 3  and 4).
Secondly, based on the mutual superpositional relations in the wells, the character of the boundary betvveen the Jurassic sub-basin sediments and other rocks, it is evident that dark-black, tectonized clays and argiloshists in the well Pč-1 (2 ,3 9 5 -2 ,7 3 3 m) represent the rocks of the oldest Jurassic age (Lias). They have visible the processes of alteration of minerals (e.g. sericitization of feldspar), which indicate a certain hydrothermal effects.
Third, the stratigraphic range of the complex of coarse clastites, i.e. breccias and conglo-breccias (KB) lying over ultramafites in vvells (Ov-1 and SA-2) is also quite clear. The clasts originate mainly from ultramafics, predominantly angular pieces of seprentinized peridotites tightly bound by cement that partially contains a high percentage of carbonates. The thickness of these breccias is from 90 m in the well Ov-1 (3 3 0 -4 2 4 ) to over 120 m (2 2 9 -3 5 2 ) in the well SA-2. In the Ov-1 well, this complex is covered with tbe tectonized Upper Cretaceous flysch sediments. No fossil remains were found in it. Since they are superpositionally located above the ultramafites and whose fragments they contain as well as they are overlying by the tectonized Upper Cretaceous flysch, their stratigraphic position probably corresponds to the Lower Cretaceous deposits or the so-called Para-flysch.
On the Belgrade side, sim ilar the com pact serpentinite breccias were discovered in well Bt 1-2 (Ljubičica-Bubanj potok) where, in the interval of 2 8 -3 8 m depth, they cover a mass of serpentinized peridotites in which drilling was completed (92m ) (R u n d ić et al., 2019).
Regarding the depth geological structure of the Neogene-Quaternary cover, it was determined that the oldest Miocene units lie discordantly over the heterochronous pre-basin bedrock. These are continental-lacustrine deposits of duoble-natured genesis. This highly interesting geological unit of defined stratigraphic affiliation (Lower Miocene), has been established in some wells much earlier (e.g. M a r in o v ić , 1959, 1961, 1962; M a r in o v ić & K em enci, 1969 ;D o l ić , 1997, 1998). In the wells Ov-1 (1 1 0 -1 6 6 m), SA-2 (1 4 5 -2 2 9 m), and G-1 (1 ,1 5 0 -1,300 m), in multicolored clastites with dominance of greenish and brown-red clays, gray-green gravelly sandstones and conglomerates, with fragments of chert, serpentinite, Mesozoic carbonates and carbonate concretions, there are not many fossil re-m ains or, w hen found, they are poorly preserved and difficult to determ ine the remains of freshwater mollusk fauna and ostracods ( M a r in o v ić , 1 9 6 2 ), fish fragm ents and pollen grains ( D u  Especially interesting is the stratigraphically synchronous series of a com pletely different genesis, which was determ ined w ithin the Pančevo depression. Pre-B adenian, gray-black sub-aquatic pelites (Pbp) of reduxing genesis (Pč-1, depth interval 1 ,9 8 0 -2 ,3 9 5 m, see Fig. 3) reach a thickness of over 4 0 0 m. A scarce content of small fern spores (Polypodiacea) was found in them, which indicates the Lower Miocene age. In our opinion, this hitherto unseparated a fine-grained m olasses series represents the tim e equivalent of the previously described the Miocene m olasses of oxidative genesis. We think that its separation as a particular unit represents an im portant contribution of this paper.
Other Miocene units that make up the basin fillin (Badenian, Sarm atian, Pannonian, Pontian, Pliocene P alu din a layers) are quite well known. However, in the studied area, they have been completely spatially and tem porally correlated by this research. Namely, the map of Neogene thicknesses presented here, indicates a system of m orphostructures built of small or larger depressions separated by structural saddles and elevations which, logically, gradually pass into each other. The disjunctively shaped space and the resulting structu ral relationships have led to the form ation of several sig-nificant depressions (e.g. Pančevo, Sefkerin, Batajnica, Grocka) and horsts structures(O m oljica, Jabuka-G logonj, Banatsko Novo Selo, etc.) w hose existence explains quite different stratigraphic relationships in depth and the present lithostratigraphic content in certain segments of this area. This has led to the fact th at the relations betw een the Miocene units are notin accordance and there are phenomena of local discordances due to the differential sinking of "blocks" (structures), erosion and denivelation of the existing relief. Good examples are the Badenian and Sarm atian sedim ents in Ovča, which are very shallowly located, thinned and have a thickness of several to tw enties m eters, while in neighboring the Pančevo depression they are downlifted to considerable depths and have a much greater thickness (up to 500 m each). In contrast, on structural elevations or sm aller horsts, som e M iocene units are very often com pletely eroded and remain present only on the flanks of these structures (e.g. Omoljica or Jabuka w here Badenian is eroded and the Sarm atian or Pannonian deposits directly overlie the Lower Cretaceous rocks - Fig. 4). On the disrupted paleohorst of Banatsko Novo Selo (BN s-1), the reduced Sarm atian sedim ents about 60 m thick, discordantly overlie the Lower Cretaceous paleorelief at a depth of 1,111 m.
A more detailed attem pt to interpret the geodynamics of the Belgrade area during the Neotectonictime was presented by Ć irić (1992). By the author, the Neogene period is characterized by radial tectonics. Some fault systems are inherited from the Mesozoic and reactivated during the Neogene and some others are the product of Neotectonic activity. All of these resulted in the author editing a sketch for a Neotectonic map and showing the main elements, types of faults, volcanic phenomena and Neogene terrains with different degrees and dynamics of sinking. Among other things, he singled out a few faults im portant for the formation of Neotectonic m orphostructures, such as the Sava and Danube faults (this second one is also m entioned by L a s k a re v , 1 9 4 9 ). So-called the Vinča fault (a right longitudinal strike-slip fault of the NW-SE direction) formed in the Mesozoic and reactivated during the Neogene, which separates this area from the Velika Morava trench at east, is especially important (Fig. 6, Ć irić , 1992).
Here we would like to note that, regardless of a certain contribution of the mentioned paper, the fact is that the fault systems presented are not based on clear factom etric orgeophysical data. By our research and by construction of the Neogene thickness map and determined structures formed on the basis ofwells data, it can be observe in principle the existence of certain faults with significantly corrected direction, size and character of movements (e.g. the Sava fault has a different orientation and the Danube fault has different prolongation], An important structural unit on the map is the Pančevo depression, located east of the described morphostructural ridge and the longitudinal row of sunken horsts of Banatsko Novo Selo-M ala Ada (Brestovik). It has a depthup to 2,600 m and N-S direction (Fig. 10). The observed sharp tectonic boundary of the Pančevo depression towards BBMR on the west side, which has a winding general direction of N-Sand marked by the flows ofthe Tamiš and Sibnica rivers, corresponds to a system of normal, lystric faults (Figs. 3, 4 and 10). Our stratigraphicgeomagnetic data indicate the sediments of the Pančevo depression formed in the early Miocene syn-rift phase (initial rifting), over which the Middle Miocene sediments ofthe riftmaximum (Badenianearly Sarmatian) and the post-rift, the middle Sarmatian sediments were deposited all the way to the Pontian time .
About the existence of a system of depressions (basins) in southern Banat has been recently reported by D u lić et al. (2019). Among other things, the authors single out the Pančevo Basin, which is one in a series of the so-called pull-apart basins formed during the Miocene and whose sediment thickness exceeds 3,700 m. They are genetically related to a complex system of longitudinal faults of the Dinaridic direction along which the space for the creation of more parallel basins was opened. According to the authors, these south Banat basins represent a part of a wider, southern chain of pullapart basins developed along the so-called Moravian Corridor. The mechanism of formation of these structures is related to stresses along regional, longitudinal faults (D u lić et al., 2019).
Our research has shown that in a relatively small area it is possible to single out several relatively deep local depressions (e.g. Pančevo, Sefkerin) which have significantly thick Neogene deposits (1 ,9 0 0 -2 ,6 0 0 m). It should be noted that the mechanism of their originin the early Miocene must certainly be viewed in the broader context of the entire southern rim of the Pannonian Basin. Terminologically, for the mentioned area, we are of the opinion that is more convenient to use the term depression than basin (e.g. Pančevo depression).
Finally, apart from the mentioned historical-geological and structural-tectonic evolution of the wider Belgrade city area, the aspect of applicability and use of certain lithostratigraphic units of SW Banat and beyond is especially interesting i.e. their depth hydrogeological zoning.
Four hydrogeological systems (HGS I-IV, see Essentially, this zoning defines how and to what extent mineralization and aquifer types change within the basin. This means that the contained mineralizations of water do not depend on the depth, but primarily on the position of the certain layer in relation not only to the contact floor package but also to the structural lateral sides, on which the cover collector eventually relies. As can be seen in the presented profile I, the water from Ovča from the Sarmatian/Pannonian contact with a depth of91 m has a mineralization of 16.46 g/1 (M ilo je v ić , 1960), and the water even from the eastern side of the Pančevo depression, from the correlatively close Pannonian collector depth of 1,013 m, has an almost identical mineralization of 16.4 g/1 (Doz-1). Correlatively slightly younger Pannonian layer of the well Do-1 with a depth of 839 m, has a lower mineralization, specifically 15.5 g/1. A stratigraphically determined Sarmatian deposits of the well Doz-1 from a depth of 1,154 m, contain a correspondingly increased mineralization of 17.85 g/1 which is close to the mentioned values from Ovča, i.e. from the Sarmatian/Pannonian contact. Waters from the Badenian reservoirs ofthe wells Doz-1 and Do-1, depth 1,602 and 1,674 m, have mineralization according to the intra-Badenian "age" by increasing the mineralization from 25.9 to 32.6 g/1, which is in ac-cordance with a m odern m arine w aters (Š a r k o v ić , 1973). Finally, w ater from the Miocene lagoon with an am bientally high m ineralization of 51 g/1 -was laterally infiltrated into a fissured collector of the Lower Cretaceous rocks (Fig. 3). It is worth mentioning that e.g. waters from the Pontian sediments (HGS-I, complex D) in Kikinda from depths of 1 ,1 0 0 -1 ,4 0 0 m, have a mineralization of 4 -6 g/1, which is the same as the mineralization ofthe level of significant reduction of caspibrackish cardids (M a r in o v ić , 2017).

Conclusions
• The Belgrade city area includes a segm ent of two m orphologically touchable geotectonic unitsthe inner Dinarides s. lato, and the southern rim of the Pannonian Basin, w ithout considering the regional geotectonic interpretations.
• W ithin the Pannonian Basin, geochronologically and depthly, it differs the subbasin unit affected by an intensive orogenic-fractured tectonization of the Alpine cycle, and, the discordant geological cover, disjunctively and compactionally formed during the post-Paleogene time.
• Within the sub-basin structure, the oldest rocks are a black, schist like, sericited pelites that are palynologically determ ined as the Early Jurassic (late Lias-early Doggerian), w ithout the content of ultrabasic magmatites.
• Serpentinized peridotites of the harzburgite type w ere drilled directly below the Neogene cover (Glogonj), then under the Cretaceous agglomerates (Ovča) as well as in the area of Lju bičica-B u ban j Potok, with an abundance of serpentinite fragments, cherts and other rocks, comparatively the early Cretaceous age. On the surface, they are already known from the valley of the Zavojnička River, Zuce and the eastern sides of Avala Mt. in a thrust, w est-vergent relationship with the Cretaceous flysch.
• By the analysis of the com bined geophysical data it is confirm ed the possibility of the existence, the pre-Senonian laccolitic intrusions of acidic magm atic differentiation Avala Mt. The presence of ultrabasite is excluded.
• Based on geom agnetic indicators, in this paper, for the first tim e, the route of ultrabasic break-throughs is presented. On the attached map, it is specifically plotted as a sub-basin depth projection of the apical axis with a general direction of N-S (Glogonj-Velika hum ka-Jabučki rit-th e Ovča railway station-M irjevo-M ali Mokri Lug-Ljubičica-Zuce).
• Orogenically tectonized the sub-basin's geological column of BBMG, generally of meridional orientation, is broken into block system s of different orientation during pre-Neogene. Besides, it is additionally modified to the disjointed basin floor configuration as the base of a heterochronous Neogene cover.
• During the Neogene, by complex fracture zones and less pronounced fault systems, depressions and antiform structural units mutually different orientations w ere formed. The m ost pronounced fault belts, partly w ith reactivated pre-N eogene depth faults, and the zones of less pronounced faults, on the constructed map ( Fig. 10) are visible in the directions and lengths by differently condensed isopaches. Drawing of these faults is unnecessary.
• Among the formed m orphostructural units, the main depressions stand out: Pančevo, Sefkerin, Batajnica and Grocka, w ith a sm aller sub-depression of Mokri Lug. The structural trenches are: Moštanica (SW corner of the map), Makiš (a bay of the Batajnica depression), Krnjača (Belgrade Danube River area), Beli Potok (foothills of Avala Mt.) and Banatski Brestovac (open to the NE).
• In the m eander of the Danube river, there is the Slanci antiform and the sm aller one, Babin Vis. On the Banat side, the horst m assifs Ovča, Jabuka and Glogonj stand out. The m orphostructural row Banatsko Novo Selo-Vladim irovac-D olovo-Bavanište, som ew hat separates the Pančevo depression from the Skorenovac-Sm ederevo depression, the w estern extension of which is visible on the attached map. The Omoljica horst-m assif, with a sm aller unit Starčevo-Ivanovo has a southeastern extension towards the antiform structures of Mala ada (Brestovik) and Orešac (outside the map).
• Below the Belgrade center, there is a structural polyfacial antiform, partly reefly row Čubura-Kalem egdan-Borča (extended to Padinska skela), then a shorter structural nose from Čukarica to Bežanija, and the separated periclinales of Ostružnica in the direction of Jakovo and Surčin.
• The oldest Neogene sediments of limited contours are lacustrine-subaquatic, multi-colored heteroclastic molasses (interbedded by volcanoclastics], in principle of oxidative genesis. This reference promotes the black and gray black, pelitic molasses of reduxing genesis, so far drilled only at the bottom of the Pančevo depression, 415 m thick. • The marine and semi-marine sediments (Badenian, Sarmatian) are discordantly overlying the different rocks, over which they lie heterochronously. Three types can be separated: the basinal-lagoon, coastal-reefly and mixed one. Each ofthem has specific lithofacial characteristics and fossil content.
• The late Miocene brackish-lacustrine sediments (Pannonian and Pontian s. str.) were developed according to the same ambiental principle, but without the peculiarities of the lagoon and reef type. In accordance with the permanently mobile tectonic oscillations, according to the disparate geometry of the floor, the different overflow-outflow relations w ere achieved, including with intraserial discordances.
• Quaternary sediments in the Pančevo depression are estim ated to be up to 150 m thick. It is goodly correlative with the Glogonj locality, where they have been paleontologically determ ined to a depth of 100 m.
• To all the above, for the practical reasons of usage, it can be added that in the whole Vojvodina basin area, the hydrochemical characteristics of water do not depend on depth, but primarily on the paleontological elem ents of the aquifer, including lateral infiltrations into the reservoir on which the stratigraphic aquifer relies. Depth geological relations ofthe wider area ofBelgrade -based on the weiis and geophysical data