_ The Formation ~

of the Geologic Framework of Serbia. and the Adiacent. Regions

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Vera Knezevic-f}ordevii Branislav Krstii

Faculty of Mining and Geology, University of Belgrade Committee for GEODYNAMiCS of the Serbian Academy of Sciences and Arts

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TEIlRANES OF St:RIJU E,k K"eievic. V & Kn/ii. n fil'. 427-432. fleI/:mde. IYYfi

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TYPES OF LATERITIC WEATHERING CRUST ALONG THE V ARDAR RIVER, REPUBLIC OF MACEDONIA

l8"'zo Boev , Todor Serafimovski

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IFnculty of Mining and Geology, ~tip, Republic of Macedonia

Abstract: This pllper is II brief (lccollIIl of Ihe slrucllll'a/-tIIelallogellic fealures of Ni-silicales alld Fe-Ni tiellO.dls in Ihe Vllrdllr wne a/ollg Ihe Vllrdar RiFeI' I'ldley ill Ihe ReplriJlic ofMacedonia

Two Iype of IlIlailic Cl'llsls were delermined: prill/llr)' lalerilic C/'llS;S - ill silfl (Grool. Gmdi.fle elc) and redeposiled 11IIerilic clI/sls (RiIlIlOVO. Siudel/ll Voda. Rllkle. Nikodin elc)

Lilierilic crllsls lire genelicolly relaled 10 lite processes of IMeriliZillioll of lire J"rassic selpellliliiles Ivlrielf look place ill 11'11/.", IIl1d wei elimale Tltey fire bllsically lIickeliferocls­ferrugineous in wlrich Ni conlelll IIIIIOllnis 10 /%. Fe 10 32 %. IIlId Cr 10 IIbOlll 2.5 %. Co. V. Mil. Ti elc. occur liS IICCOIII!lllllyillg compollenls.

KEY WORDS: weathering, lateritic crust, Vard;]r river. M;!cedoni;]

I. lNTRODUCTION

Although occlll'rences of nickeliferous mineralization in we;]thering crust in the Vard;]r Zone were known before 1941, their exploitation started a fier 1970. The FENI Metallurgical Plant in the town of K;]v;]d:Hci was built to process the III iner;! I raw materia Is. Nickel ;]nd n ickcl i ferous iron deposits in the western ophiolite belt (in Albania and Greece) st;]rteci the process of exploitation much e;]rlier til;]n those in tile Var<i;]f Zone.

The conditions for occurrence of the deposits in the Vard:H Zone were studied by many geologists. The most importnnt studies were canied Ollt by MAKSIMOVIC (1952a, 1959b, 1966, 1981), IVANOV (1962, 1975) nnd STOJANOVIC (1960). Recently. intensive investigations in the deposits in

the Kozuf district wcre carried out by BOEV (1982,1988), DOEV and JANKOVIC (1996).

2. STRUCTURAL-GEOLOGIC AND META­LLOGENETIC FEATURES OF THE LATERI­TIC CRUSTS

Silicate nickel and nickeliferous iron deposits in . the Vardar Zone are situated in a relatively narrow

belt of ophiolites striking Fruska Gora in the north to Eubea in the south continuing further to Anadolia in Turkey. Spatially, in one part genetically, the primary deposits are related to the peridotite complexes of Jurassic ophiolite for­mations, or more precisely to the weathering crusts which developed on the peridotite/serpentinites which themsevles cieveloped in conditions of wet and warm climates under the influence of surface factors. Although these deposits have features or lateritic products they can not be classified as ordinary lateritic deposits.

. Most of the fossil weathering crust was eroded during later processes, particularly in conditions of dissected paleorelief. Residual ' Ni-silicate deposits remained in places where they developed and were covered by younger sediments, that protected them from further erosion or where fossil crusts redeposited in surrollnding basins or nearby carstified vugs/troughs. Deposits and occurrences of silicate nickel and nickeliferous iron ore located in several smaller metallogenic units, mainly ·ore· fields and districts. These metallogenic units ore situated in the Serbo-Macedonian metollogenic province_

Metal10genetie analysis carried out along the course of the Vardnr River determined three ore districts: the T. Veles-Klepa, Rakle-Nikodin nnd Kohlf. They 011 have their own specific feotures with respect to IOleritic crusts and include severn I

. characteristic deposits.

3. TYPES OF LATERITIC CRUSTS

Based on results obtained from investigation carried out on lateritic crusts along the course of the Vardnr River two typcs cnn be distinguished:

I. primary lateritic crusts - in situ and 2. redeposited lateritic crusts.

Development of economically important nickelnn~ nickeliferous iron deposits could take place durin~ the development of weathering crust. Deposits of silicate nickel and nickeliferous iron are distinguished based on mineral composition.

3. t. Silicate Nickel Deposits

The following typ~s of silicate nickel ores can be distinguished based on their chemical composition: a. ferrugineous b. magnesian and c. siliceous.

I. rCllUgillCCHIS (il 1I0lltl Oil ite OICS rc(ain the structure of serpentinite. They are plastic and powdery when dry. Nontronite and nontronized serpelltinitc prcv;-ril in their eOJllposition. They also cont;-rin beidclite, chloritc, ;-rsbolnne, op;-rl, cnliloll;-rtC.S, gypSIlIll, I"nlcly nickelifcrolls hydro­silicn1es.

2. Magnesian or serpclltillitc orcs nrc very similnr to scrpcntinitcs in their physical nppcnrance. They consist of serpentinite nnn n()ntronite with minor cerolite, nickcliferous hydrosilieates (gnrnierite, revdellskinitc), c;'l\ccdony, op;-rl, iron hydroxides and mangnnese as well ;'IS carbonates (,Hagonite nnd magnesite).

1. Ocher siliceol1s orcs ;-Ire quartz silicified ores rlevclopen mainly of e;-rlccr!ony nnd opal which form vuggy cnvernOlls shapcs fillcd with loose m;-rteri,i1, mainly iron hydroxides. The Groot and Gradistc deposit belong to this type of deposits .

Table 1: Chemical analyses of materials of lateritic we;-rthering nusts frol11 the Groot deposit

1 2 3 4 5 MnO 0.35 0.18 0. 11 0. 10 0. 10

AhO~ 0.45 2.43 0.55 0.40 0.92 Tot Fe10J MgO

5.27 47.21 5.02

10.39 9.49 -.--­33.86

8.33 . -----.-35 .8<134.<1027.60

Na2.0 0.38 0. 18 0.09 0.06 0.07 KIO 0.20 0.83 0.20 0.20 0.20 SOl 0.06 0.08 0.06 0.06 0.06 P20~ 0.9 0.4 0.6 0.6 0.6 SiOl 25.06 21.87 44 .09 44 .30 42 .64 CaO 15.32 3.24 0. 10 0.06 0. 17 TiO, 0.02 0.22 0.02 0.02 0.02 CrzO] 0.02 1.17 0.02 0.02 0.25 NiO 0.11 1.17 0.37 0.33 0.31 IhO( 105) 0.81 0.44 0.6<1 0.63 1.03

The geological compOSItIon of the Groot deposit consists of ultrabasic rocks, laterites and Cretaceous limestones (Fig. I).

Nickel content ranges from 1.5 to 3 %, whereas iron from 30 to 40 %. Nepouite-garnierite aro the bnsic nickel bearers in the deposit. Chemical composition of the lateritic crust in the deposit is shown in Table I . \, I

3.2. Nlckellferous Iron Deposits

Niekeliferous iron deposits are very common in the

V:nd<lr ZOnc. They ' ;lre lll<lillly redeposited and located in the footwall of Upper Creataceous sediments. They ;-rre ill the shape of layers and 1ll00inly developed on sClpcnlillites in the footwall of sOllie sedimentary series.

The milleml composition of orcs is very complex, <lnd in some cases differs largely from the primary composition of the redeposited Intcritie material. 11c1ll;Jtitc ;-rnd lll;-lgnetitc <He most common in addition to :l fan of silic;-rte minerals sllch as chlorite, tnle, stilpnornelnne etc as well as the ell bon;-rtc grollp represented by calcite and dnlomite, nile! occnsionally J1);Jgncsite.

428

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Fig. I. Geologic map of the Groot deposit I . Alluviulll, 2_ Delluviulll, 3. TlIlollian limestone, 4. Turonian quartz conglomerate and ' sandstone, 4. Turoni<ln lIickeliferolls pisolitic ore, 5. Low grade nickel mineralization with jasper, 6. Lateritic crust, 7. Leached serpentinite, 8. Serpentinite with magnesite OCCIIITCnCeS, 9. Diabnse, 10. Serpentillitc/ Peridotite, 11. Triassic limestone with chert, 12. Carbolliferolls nWI ble, 13 . QlI<lrtz-sericitic schist, 14. Alllphibolite, !5. fault

R!ouovo, Studena VOdll, Halde etc belollg to this signs of wedging OU\. The <lvemge thickness of the group of deposits. layer is abollt 30 meters <lnd it behaves like n

continuous body, although tectonic events on the The Rianovo deposit is typical of this group. The field were very intense. nickeliferolls iron mineralization is located along the contact between Jurassic scrpentinites and Spatially, the byer has a sub-vertic<ll position and schists in the footwall as well as Cretaceous due to strong tectonic movements it has inverse limestones in the hangingwall. The ore layer was position in the part of the Rianovo deposit (Fig. 2). explored from pe<lk 955 meters to peak 470 melers throllgh a vertictll interval of nbollt 500 m. with no

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rig. 2. Geologic map of the R1anovo-Studena Voda zone

429

Thc following lithologic ore typcs cnn be (I1/Hl. stilpI10IIIl"I:lIl(: schisls (111/1), dolomite distinguished in the RZanovo ore layer: compact schists (VIII), lille schists (VIIG), serpnetinite ore magnetitc ore (I/I), schistose magmetite ore (WI), (Y16). oolite hematite ore (I12), schistose hematite ore The composition of thcse ore types is shown in (J/3), compact hematite ore (114), riebeckite schists l~blc 2.

Table 2: Chemical composition of~ajor ore types ill the IZ I.il novo depos it

111 II I I 1/2 1/3 AI,O 1.78 5.41 3.18 2.68 Tot Fc,O 32.91 59.86 59.30 40.51 MnO 0.24 0.16 0.20 0.48 MgO 18.40 8.27 9.15 17.66 Nal0 0.50 0.55 0.37 0.50 K,O 0.10 0.10 0. 10 0.10 P,O~ 0.17 0.29 0.17 0. 17 SiO, 40.02 16.05 19.80 30.]0 SOl 0.47 1.26 0.48 0.47 CaO 0.98 1.0] 2.00 0.99 TiO, 0.02 0.13 0.05 0.03 LOI 2.65 2.18 1.94 3.39 H2O 0.24 0.53 0.70 0.40 NiO 0.90 1.28 0.91 1.27 Cr20, 1.68 ] .86 1.99 1.93 Total 101.06 100.96 100.34 100.88

._ ,-­ - ­(/4 II/Ii III1 I VIII \'1/6 V /6- _.. ­

3.39 G. GO 5.92 1.'l7 1.05 1.39 48 .5 7 16.72 43 .89 ]G.55 11.J7 12.35

0.58 0.73 Cl.l Ii 0.(13 0.26 0.16 12.82 7.62 9.35 14.73 28.64 31.67 0.53 5.07 0.66 1.23 0.59 0.83 0. 10 0.22 0.79 0.19 0.18 0.20 0.24 0.36 0.49 0.-13 0.40 0.40

25.23 46.33 27.06 32.2] 48.77 41 .31 0.61 2.82 3.48 0.72 0.26 0.26 1.03 1.98 1.27 6.73 1.63 1.37 0.05 0.28 0.20 0.01 0.01 0.0 I 2.95 0.16 3.40 2.(i I 5.67 9.68 0.61 0.28 1.27 0.18 0.30 0.73 I. 1,1 2.13 0.79 0.80 0.75 0.37 3.25 7.00 2.9] 1.49 0.36 0.]9

101.10 98.30 101.68 99.80 100.04 101.l2

Mineral association of the ore in the RZanovo (11116 %), hemiltite (40,41 %), clinochlore deposit is as follows : magnetite, hematite, (10 .G5 "In), tille (22.90 %), ilild Illilgnesioriebeckilc c1illochlore, talc, sepiolite, l11agnesioriebeckite, (13GO%) lizardite, dolomite, phlogopite, stilpnomelane, quartz, albite, pyrite, maghemite, pyrrhotine, The all10llnt of major and accompanying metals in digenite and millerite. the (Icpos i! ;1I110llllls to . 1.03'('0 Ni, 32% fe, 0.06%

Only five of the mentioned mineral Co, 225% Cr. associaiions are cOllstantly present: magnetitc

Table 3: Chemical composition of major ore types ill the Studena Yoda deposit

7781 7713 7718 7721 772] 7567 7569

Si02 18.55 ]3.61 .

35.15 .

18 .76 25.07 28 .64 21.56:w; AI2O)

Cr20)

0.42 11.12'

0.23 0.56 0.2 9 0.] I 0.42 ' 0.58

5.08 12. 15 8.21 8.46 5.35 8.40

4.47 1.12 ].02 2.15 1.87 2.53 1.96

f(20) 35.47 26.1] 5.25 40.38 37 .59 35 .11 42 .64

fcO 12.53 2.50 7.86 ] .88 6.44 5.99 7.07 MnO 0.42

1.91 0.36 0.45 0.34 0.38 0.45 0.63

NiO 1.20 1.40 1.15 1.26 2.01 10.50

1.12 6.75MgO 7.86 20.00 20.59 16.18 9.22

CaO X 3.27 0.90 3.]7 0.13

-- ­0.07

1.57 1.92

- - ­208

1.25 1.46

Na20 K20

0.06 0.11 1.07 2.45 0.4 0

0.07 0.06 2.2R 1.17 2.76

II20+ 6. 16 5.75 8.5 r\ 5. 15 3.58 3.57 4.30

H2O' 0.89 0.58 0.59 -

0.93 0.35 0.51 0.36

Tolal 99.93 100.00 99 .9 1 -­

101.19 - .. ­

100. 10 99.95 100.26

Ni(%) 1.50 0.94 1.10 1.06 0.99 1.58 0.88

430

Besides Rianovo, the Studena Vod;J, which ha s certain specific fe;Jtures , is all imrort;lIlt deros it in this lateritic group. (;eological relationships in the deposit are similar to those in Rzanovn, the difference being in the serpenlinites located ill the footwall of the ore layer. In RZanovo they arc located and compose the h<lngingw<lll of the ore I<lyer due to the ·innuence of strong tectoni c movements.

In Studen<l Voda deposit the hnngingw<lll is composed of Cret<lceous limestones <lnd Terti<ll), tuffs, whereas thc footwall consists of nontron itc cI<lYs and serpentinites or relicts of I<ltel ili c serpentinite weathering crust (foig . 2).

The thickness of the layer amounts to 50 m <lnd in p<lrt it is covered by series of tuffs.

The texture of the l<lyer is not homogeneolls and consists of a number of lithologic members or ore types (MAKSIMOVIC, 1982, 130EV, 1982, 1990): chlorite-hem<ltite type (7781), talc-ehlorite­hemlltile type (7713), chlorite-phlogopite t<llc­amphibole type (7718), hematite-chlorite tyre 7721), hematite-chlorite-phlogopitc-<lmphibolc type (7567), hematite-phlogopile-chIOJite type (7569), phlogopite-<llbite ore type

The composition of major ore types of the Studena Voda deposit is given in T<lble 3.

The contents of basic ore mct<ll s in the Stlldena Vod<l deposit amount to 1.05 % Ni , 31 % Fe, 1.85 % Cr, 0.05 % Co.

4. CONCLUSION

Deposits of silicate nickel and nickcliferous iron in the Vardar zone are situated in a rcletively narrow ophiolite bell. Sp<ltially and in some rart genetically, primary derosits are relatcd to the peridotite complexes of the Jurassic orhiolite formations, or more precisely to the we<lthering crust which develorecl on the peridot ites/ serpentinites which themselves devclored in conditions of wet and warm climates under the innuence of surface [<lctors.

Most of the fossil we<lthering crust W<lS eroded during l<lter processes, p<lrticularly in conditions of dessected p<lleorelief. Residual derosits of Ni ­silicate rem<lined in pi <Ices whele they were either covered by younger seJilllents th<lt protected thel11 from further erosion or where fossil crusts redeposited in surrounding basins or nearby karstified vugs/trollghs .

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MAKCI1MOBl1n, 3., 1980: THnoDH pa31lllhn cpoCl1nlll1X Kopa pacnClnaIba Ha ynTpaMa­CPH'HlI1M CTeHnMa bClJ1KnIlCKOr IIony­oCTpoBa. CI1Mn: AnTepaUl1ja CTeHa Ii

MI1Hepana, Py~apcKo-reonowKI1 cpaKyn­Tel', 18-25, Eeorpan.

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cpaKynTeT, 39-43, oeorpag.

:i!

,. ' l

..

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MI\KSIMOVIC, Z , PANTO, GY ., 1982 B: The main ni ckel -bcaring pha~es in the Rlanovo oeposit, Yugosl;1Vi a: chlorite, tnlc" stilpnomelane ;lI1d magnesioribeckite. BIIII.Ac<ld . Serbc Sci .Arts, 82, 23, 77-96, Rclgl<ldc.

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CKOIIOMC KII 311:J ' lnj. TpYA. reo. 3aB. HPM . 7 (1959),181·197, CKonje.

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