I 
GEOL. CROAT. 49/1 117 - 127 8 Figs. ZAGREB 1996 I 

Eocene Limestones Overlying Lower Cretaceous Deposits of 
Western lstria (Croatia): Did Some Parts of Present lstria 

Form Land During the Cretaceous? 

Dubravko MA TICEC' . Igor VLAHOVIC ', Ivo VELIC' and Josip TISLJAR' 

Key words: Cretaceous tec toni c cyc le, Cretaceous 
land, Western Istrian anticl ine st ructure, Transgres­
sive Eocene limestones, Adriatic Carbonate Plat­
form, Tstria, Croat ia. 

Abstract 
In the region of (he western Islrian anticline, eros ional remains of 

lhe transgressive Eocene Foraminiferal limestones overly shall ow­
water deposits of Early Cretaceous age (Valanginian, Hauterivian and 
Barremian). This evidence, together with the ocurrencc of baux ite 
deposits and Palaeogene beds overlying Albian, Cenomanian and 
Senonian limestones indicate the very high relief of the land trans­
gressed by the Palaeogene sea. Contrary to the traditional connection 
belweellthe formation of the western Istrian anticline and the Larami­
an tectonic phase at the end of the Cretaceous (Maastri chtian), new 
investigations suggest sporadic tectonic movements (w ith conslall! 
tectonic coordinate orientation) from the Hauterivian to the end of the 
Cretaceous. With these movements, formation of the anticline struc­
ture began in the Early Cretaceolls, with the emerged apical paris rep­
resenting land areas throughou t most of the Cretaceous. 

I. INTRODUCTION 

Recent systematic geological investigations in west­
ern Istria (Fig. 1), espec ially during research for the 
1:50,000 scale Geological Map of the Republic of 
Croalia indicate a need for a new interpretation of the 
geological evolution of the Istrian peninsula during the 
Cretaceous and older Tertiary. Previous interpretations 
were based on the results of investigations for the Basic 
Geological Map (POLSAK & SIKIC. 1969), as repre­
sented in the explanatory notes of thc Rovinj sheet 
(POLS AK & SIK IC, 1973) . 

The authors of subsequent papers 011 the geology of 
central and western 1st ria accepted the tectonic scheme 
from this work, where the dominant st ruc ture, the 
NNE-SSW oriented western Istrian anticline, is inter-

I tnstitlltc of Geology, Sachsova 2, HR-l 0000 Zagreb, Croat ia. 

2 Faculty of Mining, Geology and Petrolcum Engineering, University 
of Zagreb, Pierottijeva 6. HR- I 0000 Zagreb, Croatia. 

Kljucne rijeci: kredni tektonski ciklus, kredno kopno, 
zapadnoi starska antiklinalna struklura, transgresivni 
eocenski vapnenci, J adranska karbonatna platforma, 
Istra, Hrvatska. 

Sazetak 
U podrucju zapadnoistarske alltikJillale utvrdene su pojave erozi ­

jskih ostataka transgresivnih eocenskih foraminiferskih vapnenaca na 
pl itkovodnim nas lagama donje krede (valendis u, otrivu i baremu). Ti 
nalazi zajedno s pojavama boksita i paleogenskih naslaga na albskim, 
eenomanskim i senonskim vapnencima, ukazuju na izrazit reljef ko­
pna na kojc jc transgrediralo paleogensko mo re. Nasuprol dosada­
snjern vezivanju nastanka zapad noistarske antiklinale za laramijsk u 
lektonsku fazu krajem krede (u mastrihtu), rezu ltati novijih istraziva­
nja ukazuju da su povremeni tektonski pokreti djelovali od otriva do 
kraja hede s istom orijentacijom tektonskih koordinata. Tim je 
pokretima vce u starijoj kredi zapocc1o fonniranjc antiklinalnc s tru­
klure, cij i je emergirani sred isnji dio predstavljao kopno tijekom 
gotovo cijek krede. DakJc, podrucje zapadnoistarske antiklinale jc u 
mlademu dije lu starije krede i mladoj hedi bilo kopno! 

preted as being fo rm ed by the end of the Late Creta­
ceous during the Laramian tec tonic phase. As the influ­
ence of the Laramian tectonic phase declined by the end 
of the Cretaceous and beginning of the Pa laeogene, the 
new, Pyrrenean tectonic phase began. This was charac­
terised by a change in the orientation of the compres ­
sion of the carbonate platform, i.e. the greatest principal 
st rcss was oriented NE-SW. As orogenic movements 
occurred in the NE hinterland of the newly formed 
basin, as evidenced by the sedimentary succession from 
the Foraminiferal limestones to flysch, incomplete suc­
cessions are not unusual. In some places different units 
of the Foraminiferal limestones are missing, and else­
where flysch was deposited directly over Cretaceous 
beds (POLSAK & STKTC, 1969; MAR1NC:JC, 1986). 
The fly sch deposits in central Istria (from Brtonigla to 
Labin) represent the SW part of the fonner tlysch basin 
with a Dinaric orientation (NW-SE). Through further 
compression the NE part of the basin was partially con­
sumed by underthrusting beneath the Cicarija mountain 
range, and became part ially involved in its nappe stru­
cture. 



I I R 

Savudrija 

~==~"D"'vigrad • 
Rovinj 

Kolone 

v.BrijunV 

o 

Despite the intense regional tectonics which resulted 
in the uplift of the Dinarides, the area of wes tern Istria 
suffered no int ense structural -tectoni cal deformat ion. 
Thi s is probably the consequence of deformation of the 
rl ysch basin which resulted with the early fonnalion of 
the regiona l underthrusting zone. In this way the 
rcs istence against the movement of the SW part of the 
pJatfonn decreased significantly, and it started to under­
thrust towards the NE. While the basic structure of the 
penin sul a, i.c. SW part of the bas in , remained ra ther 
undisturbed, the a bducted part was strongly contracted 
and tectoni cal ly deformed. Younger, Po st-Miocene 
movements are characterised by a regional stress orient­
ed approximately S-N (MA TICEC, 1994), and resulted 
in the formation of new structures with the charac teris­
tic E-W orien tation of the b-axis. 

MARI NC IC & MATlCEC (J989, 1991) have con­
firmed the a forementi oned orienta tion of the wes tern 
Istri an structure (b-axi s oriented 35/8) by detailed field 
investigati ons, and determined the basic orientation of 
the tectonic coordinates of the Larami an phase in the 
region of lstria. Therefore the present structural fabri c 

f. 
0 

D 
D 
D 
D 

20 km 

6 

5 

4 

3 

2 

1 

Geolog ia CrO<lJica 49/ 1 

Fig. I Geological ~kc !ch map of 
ISlri a (modifi ed nfler Ihe 
Geological Map of SFRY 
1 :500.000, pllbli~hed by Ihc 
Federal Gcological lnslilul c, 
l3elgrade, 1970) wit h Ihe lo­
calit ies mentioned in the lext. 
Legend: I) Jurllssie; 2) Low­
er CreIllCeOL1S: 3) Upper Cre­
laeeous; 4) Palacogene Fora­
miniferallimeS10 llCS and fl y­
sch deposi ls: 5) lnvesl igalcd 
occurrences of Ihe Eocene 
Forami niferal limcslo ncs: 6) 
Axis of Ihc weS le rn [slria1l 
antic line. 

and orientation, as well as the timing of the fina l forma­
tion of thc wes tern Istrian ant ic line are well known. 
However, traditional view of a structurally stable Istria, 
characteri sed by the continuous deposition oj" carbonate 
platform deposits ovcr the enti re area throug h the C rc­
taceous and subseque nt gentl e fo lding with important 
e rosion during the La ramian tectonic phase, cannot 
explain some new di scoveries in stratigraphy and tec­
tonics or western Istria. 

2. STRATIGRAPHIC POSITION AND 
CHARACTERISTICS OF FORAMINIFERAL 

LIMESTONES IN THE VICINITY OF 
SV. LOVREC AND VISNJAN 

Fi gure 2 represents a geological ske tch-map of the 
area ncar Sv. Lovrec showing the outcrops or the 
Eocene FOI'amini fcral limestones, which transgressiveJy 
ove rlie Va langinian (Fi g. 2, A) and I3 arremian lime­
stones (Fi g. 2, B), in the fo rm of a small e ros ional 
relics. The Valanginian deposits are characteriscd by 



M<llicec. Vlahovic. Velie & Ti.~lj;lr: Eocene Lime~10ne$ Overlying Lower Crcl:1ccOU~ Dcpo~ilS ... 119 

" 

0.1 0.2 0.3 km 

G a 
lZEJ 6 

Fig. 2 Lilho!>lraligraphic sketch Illap of the Sv. Lovrec area. Legend: 
1) Valangini an and liauterivian deposits: 2) Barremian deposits ; 
3) Erosional relics of the Eocene ForaminifcrallimcslOne - A} 
overl ying Valangin ian, B} overlying Barremian: 4) Normal geo­
logical boundary: 5) Faults: 6) Roads. 

the rhythmical a lternation of light -coloured mudstones 
wit h pell etal paekstones, and favreina-intraclastic grain­
stoncs containing the following microfoss il assemblage: 
Ep;lIIasfOpora cekici RADOICIC, Safpil/goporefla iSfri­
aI/a GU S IC, S . pra!l/r/ol/i DR AGASTAN, I-Ielero­
poreI/o pOl/cico/corea CON RAD & RADOICIC, 1"0/­
so/ikol/ el/a call/pal/el/sis (AZEMA & JAFR EZZO), 
Dissocfadella halfter;viana MASSE, Vercorsella lellllis 
(vE LI C & GUSIC), v. call1posa,,rii (SARTONI & 
CRESCENTI), I' se"dolexlI//ariella sa/evel/sis· CI-lAR­
OLLAI S c( a i. , Ciloella? f ovrei CI-lAROLLAIS e( ai., 
Trocholil/o sag illoria ARNAUD- vANNEAU, T. de/­
phillellsis ARNAUD- V ANNEAU, Favreilla f/jegoscl/­
j'is BRONN IMA NI ,ctc. Barremian deposits are reprc­
sented by the alternation of miliolid wackestones, os tra­
cod mudstones, skeletal -peloid-intraclast grai nstoncs 
and gas tropod-mollu sc grains tones/floatstones (Fig. 
3A). Their age is detemined by the frequent occurrencc 
of foss il algae and benthic foraminifera: Salp;ngoporel ­
/a lII e/ilo e RADOICIC, S. IIIlIehihergii (LORENZ), S. 
genevellsis CONRAD, Prafur/onelfa danifovae (RAD­
OICIC), Cy/illdrol'ore//o il'allovici (SOKAC), /-llllllie//o 

B 

A 

Fig. 3 $v. Lov rec B tocality: A} A photomic rograph of sketclal ­
peloid-int raclas t grainstone of Barremian age, x6.5; B) A pho­
IOlllicrograph of the Eocene Foramini feral limestone, x4.5. 

pllpl/olensis SOKAC, C/ypeino so/kol/i C ONRAD & 
RADOICIC, C. sOlllalica CONRAD c( aI., Sobolldio 
lI/inlllO (HOFKER), Nova/esia dislorla ARNAUD­
vANNEAU, N. cornllcopia ARNAUD-vANNEAU , 
D ebarina haholfllercJlsis FOURCADE et a I. , P.';ellc!of/ ­
WIIIJl%cl/lino sp., etc. 

In the samples of the Palaeogene limestones thc fol ­
lowin g microfossil assemblage has been de termined: 
Numml/litcs sp., Assililla sp. , Discocyclifla sp. , LefiliclI­
laria sp. , Rotalia sp. , ?Fabiania sp. , ?corallinaceae or 
?A cervulilla (i.e. red algae or inc rusting ro raminifera, 
indeterminable because of the recrystallisation and par­
tial dolom itization of the sediment) , as well as c ri noid 
plates and relics of bryozoans, molluscs and corals . 
Such an assemblage indicates a Lute tian age, and can 
be comparee! with the uppermost part of the NumnHllite 
Beds elsewherc in the Adriatic Carbonate Platf orm. It 
should be mentioned that fora minifera are speeirically 
indeterminable because of the intense wea the ring and 
reerystallisation - they arc mostly di ssolved, and only 
skeletal vo ids are preserved. The limestones are 
intensely rccrystallised with late diageneti c dolomitisa-



120 

..... : ..... . .... .. 

[J2 

~5 
Fig.4 Geological sketch map of the area near Visnjan (simplified 

after POLSAK & SIK1C, 1969). Legend: I) Lower Cretaceous 
limestones; 2) Eocene Foraminiferal limestones; 3) Studied local­
ities; 4) Faults; 5) Roads. 

lioll of skeletal-peloid wackcstonc/packstones to floa1-
stones, composed of mechanicall y destroyed bioclasts 
and more or less recrystallisecl nne-grained peimicrilic 
matrix (Fig. 3S). Grains range in size [rom peloids and 
bioclasls smaller than 1 Illm to foraminifera tests larger 
than 15 111111. 

According 10 the Basic geological map of the Rov­
inj sheet (POLSAK & SIKIC, J 969) outcrops of the 
Eocene Foraminiferal limestones closest to Sv. Lovrec 
were found ncar Visnjan (Fig. 4). Among several out­
crops presented on this map two localities, Labinci and 
Markovei, were investi gated in detail for the present 
study. At both localities it has been determined that the 
Eocene beds arc overlying Hauterivian deposits. 

In a detailed measured column ncar Labinci (Fig. 5) 
peritidal mudstones, skeleta l waekestones and pack­
stones contain the following microfossil assemblage: 
green algae Clypeilla solkani CONRAD & RADOICIC 
and Salpingopore/fa al/nula/a CAROZZI, and forami­
nifera Campane/fIlla caplIensis DE CASTRO, indica­
ting an Upper Hauterivian age (Fig. 5A). In the Palaeo­
gene foraminifcral packstonc/grainslones (Fig. 5B), the 
following assemblage indicating a Lower to Middle 
Eocene age has been determined: AcervulillG ogorrnani 
(DOUVILLEl), Sphoerogypsilla globllia REISS, NIIIII­
lJIulites sp., Dermatolitholl sp., Alveolil/a sp., Lenticu-

Geologia Croatica 49/1 

laria sp., Rotalia sp., Gyroidina sp., Asterigerina sp., 
Cibicides sp., as well as skeletal remains of bryozoans, 
molluscs and corals . 

Near Markovei village the Hauterivi an limestones 
with Sa/pingoporel/a annu/ala and Campane/lu/a 
capllensis (Fig. 6A) arc overlain by the Eocene Fora­
miniferal limestones (Fig. 6B) containing a rich micro­
fossil assemblage: Acervlllina ogormani, A. linearis 
(HANZA WA), Cavilierina valiellsis (RUIZ DE GA­
ONA), SplwCI'ogypsina globu/a, Discocyc/ina agllstae 
(VAN DER WEIJDEN), D. selia (D'ARCI-IlAC), D. 
radians (D' ARCI-lIAC), Peysollelio allliqllo JOI-IN­
SON, Alveolilla levanlilla HOTTINGER, Miniacino 
lIIallicamerala (SCHEIBNER), Elhelia alba (PFEND­
ER), Nlimmulites sp., Assi/ina sp., Asterocyclina sp., 
Cihicides sp ., Notalia sp., Orbitolites sp ., Textularia 
sp., Gyroidina sp., Lenticll/aria sp., Spirolilhon sp., 
Litho/amnillm melobesillm (FOSLIE), Lithophyllum sp., 
and bioclasts of crinoids, molluscs and echinoderms. 

3, SYNSEDIMENTARY TECTONICS IN THE 
CRETACEOUS DEPOSITS OF ISTRIA 

Cretaceous orogen ic movements in the Mediter­
ranean region affected the Adriatic Carbonate Pl atform. 
To define these compressive movements it is necessary 
to explain the relationship between the continuous 
regional tectonism and the sporadically discernible con­
sequences of the synsedimentary deformation. 

The period of dcformation caused by the regional 
stress of the same orientation represents a tectonic 
cycle. Ccssation of the stress results in cessation of thc 
deformation, and lhe change of its orientation results in 
new deformation, i.c. a ncw tcctonic cycle. The process 
of deformation is usually gradual, bcing composed of 
the individual episodes of increased tectonic activity 
(i.e. parts of the tectonic cycle - tectonic phases), and 
relat ively calm periods between them. A tectonic cycle 
is defined by its duration, the orientation of its tecton ic 
coordinates (the greatest principal stress and position of 
the B-axis), and direct ion of the tectonic transport. 
Hence, it is recognisable in time and space. Its cessation 
is marked by the maximum defonnation. Therefore the 
deformation represents a cumu lative process - during 
cac h phasc in a cycle deformation being added to the 
Conner phase. Consequently, in consideration of thc tec­
tonic activity in the Cretaceous of Istria we have to start 
from its youngest records working backwards towards 
the older ones with the same tectonic coordinates, as 
follows: 

a) Bauxite deposits in Istria arc most commonly sit­
uated above the Cenomanian deposits. Bauxitic materi­
al had fiHed depressions in the relief formed by the ero­
sion of junctions of lhe youngest, Post-Cenoma nian 
joint systems (MARINCIC & MA TlCEC, 1989) with 
orientations corresponding to hOO and OkO joint systems 
of the western Istrian anticlinc (i .c. NNE-SSW and 
ESE-WNW). 



Maticcc, Vlahovie, Velie & Tisljar: Eocene Limeslones Overlying Lower Cretaceous Deposits .. 

Agel Lithology I Description 

" m 

- - -w """ -"", - --c - ,- """ "0" - Foramini feral 
"00 - c_ 

packstJgrainst 

~tIl9 .... LB·S 

Palaeokarslified. 
.... LB·4 brecciated 

mudstone 

Light·coloured 
mudstone 

C 
oJ 
";; 
.~ 

S 

'" I 
Ui 
0 
E Ostracod 

Q; mudstone 

Cl. .... LB·3A. LB-3B 
Cl. .... LB·ZC Peloid ::J .... LB·ZA. LB·2B mudstone 

Covered 

.... LB·IA. L(l·HJ 

Fig. 5 Detailed geological column at the Labinci locality; A) A pho­
tomicrograph of the Upper Hauterivian limestone with Sa/pingo­
porel/a (lIilll/fafa CAROZZI and Call/pallettuta capl/cll.l"i.l· DE 
CASTR O, x20; B) A photomicrograph of lhe Eocene Forami­
niferal limestones (bioclastic packstone) containi ng nummulilid s 
and alvcolinids, x5.5. 

b) Facies differentiation that has been recorded at 
the beginning of the Cenomanian in thc arca of Istria is 
a consequence of the synsedimentary, compressive tec­
tonic activi ty (VLA HOVIC et aI., 1994; TISLJAR ct 
a I. , 1995). In southcrn Istria ncar Banjole, a tilting of 
the platform towards the ESE has been determined. The 
distribution of the contemporaneous different facies in 
northern 1st ria , near Savudrija, is also characterised by 
the same ori entation. The lateral extent of the faci es 
belts, as well as the orientation of ripple-axes in the 
Cenomanian (NNE-SSW), corresponds to the orienta­
tion of the western Tstrian anticline. The highest parts of 
the struct ure probably remained emerged until the 
transgression in the Palaeogene: in central Istria bauxite 
deposits overlie either Albian deposits (Prhat) or Mid-

Fig. {) Markovci tocality: A) A photomicrograph of the Upper Hau­
(Crivian limestone con1aining Solpingopore1la anflutalo CARO­
ZZ I and COlJlpolleflllla capucl/Sis DE CASTRO, x35; B) A pho­
tomicrograph of the Eocene Foraminiferal limestones (bioclast ic 
packstone) with nlllTlmlllitids, discocydinids, etc ., x5.5. 

121 

B 

A 

B 

A 



122 Geologia Cro:l1iC0l49/1 

Palaeogene 

Santonian 

Coniacian 

Turonian 

20 km 

Albian 

Aptian 

Barremian 

Hauterivian 

Valanginian 

Berriasian 

Marusiti Prhati Visnjan Sv. Lovrec A Sv. lovrec B Kelone Mrlera 

Fig. 7 A SC ilClI1<llic correlation showing the position of Eocene Forarnini fera limestones overlying different stratigraphic levels of the Cretaceous 
(Valangini;Hl 10 Santonian). 

die to Upper Cenomanian deposits (Pazin area -
POLSAK & S IKIC , 1969) , wh il e in northern ISlria 
(I3l1zel aneI Karojba DROBNE, 1977; Marus ici -

YELIC & YLAHOYIC, 1994) Palaeogene Foraminife­
ral limestones lie on the Upper Cenomanian beds. 

c) 'fhe complete area of western Istria was emergent 

during the major part of the Aptian, and during the 
Lower Albian. There are no clear structural indications 

as to the coordinates and character or the tcctonics, but 
the influence of the synsedimentary tectonics is evi­

denced by the palaeogeographical situat ion in this peri­
od or the Lower Cretaceous in the Iso'ian part of the 
platform, In the central pan of the Western Istrian 
structure (Baderna - Heraki area) the emcrsion started 
during the Latc Barrem ian , and lasted un t il the Late 
Albian , On the limbs of the structure deposition contin­
ued in the Early Aptian, but with latera lly distinct dif­
ferent facies: in the SE part (Dvigrad - Kanfanar - Veli 
Brijull area) massive lagoonal oncolite miCl'ites were 
deposited, while in the NW part (Heraki - Cervar area) 
there are limestones originating from the shallow-water, 
higher energy environments. Over the major part of the 

structure emersion started during the Early Aptian, but 
in (he Dvigrad - Kanf'anar area deposition was pro-

longed even to the basal part of the Late Aptian. All 

these areas were nooded by the transgression in the 

Laic Albian (YELIC el aI., 1989; TISLJAR cl aI., 
1995). 

d) Our recent investigations in the Kolone Cove (SE 
of Rovinj ) indicate synsedimentary tectonics in the 

Hauterivian, with the orientation of the greatest princi ­

pal stress corresponding to the aforementioned episodes 
(c. 308°). 

The constant orientation of the tectonic coordinates 

of the aforementioned movements during different peri­

ods of the Crefaceous indicate that they belong to a sin­

gle tcctol/ic cycle, with activity evidenced sporadically 
from the Hauterivian to the end of the Cretaceous. 

4, PALAEOGEOGRAPHICAL 
CONSIDERATIONS 

Eoccne Foraminiferal limestones transgressively 

overlie deposits of different stratigraphical levels (Fig. 

7). In addit ion (0 the described Valanginian and Bar­
remian examples near Sv. Lovrec and those of (he Hau-



iv1aticec. Vlaliovie. Velie & Tisljar: Eocene Limestones Overlying Lower Crdaceoll~ Deposits ... 123 

terivian near Visnjan, TUNIS et al. (1994) reported 011 

Nummulite limestones and breccias in contact with the 
Hauterivian limestones in the Kolone Cove (SE of Rov­
inj). From previous studies there are data on Palaeogene 
deposits overlying Albian carbonates North of Visnjan 
and Cenomanian sedi ment s in central and northern 
lstria (POLSAK & SIKlC, 1969; DROBNE, 1977), as 
well as the Senonian of southern Istria and in the vicini­
ty of Labin (POLSAK, 1967; STKIC ct a\', 1969), 

Besides three very important long-lasting emersions 
influencing 1st ria (Kimmeridgian - Late Tithonian, Bar­
remian/Early Aptian - Late Albian, and Cretaceous -
Palaeogene) shan emcrsio ns were so frequent during 
some periods (e.g. Hauterivian, Barremian) that they 
represent a specific characterist ic or the facies. Parase­
quences, i.e. shallowing-upward cycles , usually ended 
by emersion, arc commonly composed of clayey mater­
ial and frequent black-pebble breccias. Considering the 
ract that during these periods there arc traces of 
dinosaur activity, the palaeoenvironment would proba­
bly represent a wide coastal zone surrounding the land, 
with peritidal deposits and numerous coastal swamps. 
During periodic relative sea-level oscillations black, 
reductive swamp deposits were reworked and rede­
posited by tidal channels in neighbouring intertidal and 
shallow subtidal environments. 

In western 1st ria there are several localities with 
dinosaur footprints which span a broad st ratigraphic 
range (Late Barrem ian, Late Albian and Late Cenoman­
ian) and bone remains (Late Hauterivian/basal Barremi­
an). DALLA VECCHIA & TAR LAO (1995) made 
some very interesting palaeogeographic interpretations: 
on the basis of the available data they concluded that 
1110st of the anima ls were carnivorous, i.e. they needed 
a land area large enough to enable their survival by sup­
porting herbivorous animals, which need huge amounts 
or plant materi al, as well as fresh water. It sh ould be 
emphasised that the environments where the footprints 
were found, with conditions favourable for thei r preser­
vation, were not a habitat of the dinosaurs . They lived 
on the land, and probably only transgressed across the 
coastal areas. With regard to the repeated occurrence of 
root prints which span a lengthy stratigraphic range, it 
may be concluded that Ist ria rcpresented a suitable area 
ror their colonisat ion and existcnce during the Creta­
ceous. Sincc the apical parts or the western Istrian anti­
cline represented the land arca with a changing surraee 
due to the interaction of tectonic and eustatic factors, it 
is poss ibl e to suppose at least occasional connection 
with neighbouring larger continental areas. 

Tn the area or Ist ria there are two levels of bauxite 
deposits: between the Oxfordian and Upper Tithonian, 
and Cretaceous and Palaeogene. Whi le the footwall of 
the Jurassic bauxites is of the same age in all localities, 
the rootwall of the younger bauxites belongs to the dif­
ferent levels of the Cretaccous - mostly to the Cenoma­
nian, but in the area of Prhat to the Albian . This indica­
tes that the bauxitic material was accumulated in the de­
pressions of subaerially exposed rocks of different age. 

Aforementioned findings of the bauxite deposits on 
the Albian and Cenoman ian, as well as Palaeogene 
Foraminiferal limestones on the Lower Cretaceous con­
siderably alters the probability of the intense erosion or 
the Cretaceous deposits , which was proposed in the for­
mer interpretations. Lack of the younger Cretaceous 
deposits was interpreted as a consequence of significant 
erosion after the Santonian. Howeve r, discovery of 
Palaeogene deposits overlying the Valanginian, Hau ­
terivian and Barremian beds indicate the absence of the 
upper part or the Lower Cretaceous and complete 
Upper Crctaccous beds prior to the Palaeogene trans­
gression, which would correspond to more than a 2.000 
m thick sequence of carbonates deposited in the neigh ­
bouring areas or southern Istria. This fact indicates on a 
very low possibility that during the Cretaceous/Palaeo­
gene transition huge amount of deposits, of laterally 
variable age (the footwall or the Palaeogene deposits 
ranges from the Valanginian to the Santonian/Campan­
ian) were eroded without any relics, and without any 
evidence of intense tectonics. \Vithout excluding some 
su baerial erosion, or possibly somewha t condensed 
deposition, we consider that in the discussed areas of 
Istria, the major part of thc Cretaceous deposits was not 
deposited, as a consequence of thc relatively mild, but 
during the Cretaceous continuously present synscdi ­
men tary tectonics. Consequently, these facts indicate 
that the lack of the Upper Cretaceous and, partly Lower 
Cretaceous deposits in western Istria is probably lhe 
consequence of a long-lasting phase of terrestrial expo­
sure in Istria rathcr than the subsequent in(ense erosion 
of a completely depositcd sequence. 

5, PALAEOGEOLOGlCAL EVOLUTION OF 
WESTERN ISTRIA THROUGH THE 
CRETACEOUS AND PALAEOGENE 

Occurrences of the eros ional re lics of the Palaeo­
gene limestones on the different stratigraphi cal mem ­
bers of the Lower Cretaceous deposits of lstria, as well 
as thc other racts presented in this paper enable modifi ­
cation of the traditional interpretations of the tectogene­
sis of lstria . Contrary to th e former opinion that th e 
anticline structure of the peninsula is a consequence of 
a single tec(onic act at the end of the Cretaceous, it may 
be concluded that Istria was subjected to gentle, but dis­
tinct tectonic movements during the major part of the 
Early and the complete Lat e Cretaceous. These move­
ments led to important palaeogeographic changes, since 
in the shallow-water environments of the carbonate 
platform even small elevations result in an entirely dif­
ferent facie s distribution, and the es tablishmcnt of 
rather spacious land arcas (Fig. 8A, B). The extent of 
the land was changing during the Cretaceous, depend­
ing upon the relation bet ween the synsedimentary tec­
tonics and the eustatic changes; therefore the position 
of the shoreline was variable (Fig. 8C). The land repre­
sentcd a good habitat for dinosaurs, since in the border-



124 

ing areas probably large swamps with flourishing vege­

tation existed. Sporadically these animals, (most likely 

during their searc h for food ) went to the marginal 
marine environments, w here they left their traces in a 

soft sediment. 

During the sporad ic episodes of sea-level ri se there 

was probably a partial floodin g of the inland area of the 
wes tern lstrian anticline , e.g. in the Dinarides there is a 

regionally recorded drowning of the platform in the 
Late Cenomanian and Early Turonian COUSIC & 
JELASKA, 1993). As the apical parts of the structure 
represented the emerged area, during the sea-level rise a 

probably relatively thin succession of sedim ents was 
deposited in the marginal parts, which was eroded dur­
ing subsequent sea-level fall (Fig. 8C). 

On the basis of cu rre nt know ledge, the only ev i­

dence of flooding of the inner part of the uplifted, inner 

part of the pl at form, are outcrops of th e Palaeogene 

Foraminiferal limestones mentioned in this paper. Their 

existence should be analysed in the light of the palaeo­

geographic situation in the lstrian part of the Adriatic 

Carbonate Platforrn during the Palaeogene. Due to the 

change of the regional stress orientation, i.e. the begin­

ning of the new, Tertiary tectol/ic cycle, a sedimentary 

basin of Dinaric strike (NW-SE) was formed. Fora­

miniferal l imestoncs were deposited in its marginal 

parts, whi le in the deeper, central parts flysch deposi­

tion took place (Fig. 8D). During the episodes of rela­
tive sea-level rise the inner parts of the western Istrian 

anticline were flooded, as evidenced by the deposition 

of the Foraminiferal limestones. Thi s, SW slope of the 

basin represented the source area [or part of the calcare­

ous material in the flysch deposits, and BABIC et a1. 

(1995) have determined palaeotransport directions 

towards the N-NE. It should be emphasised that the 

preservation of the Foraminiferal limestones on the old­

er Cretaceous deposits after prolonged subaerial expo­

sure represents an exception, not a rule. Anyway, it is to 

be assumed that additional similar findings will be 

recorded during further detailed work. 

It is vcry important to bear in mind that Istria repre­

sents (due to the relatively weak disturbance by the 

younger tectonics), a very suitable area for the study of 

the geological history of the Adriatic Carbonate Plat­
form during the Mesozoic. The described dynamics of 

the Cretaceous events could also be expected therefore 

in the neighbouring areas, since there is a common 

absence of at least part of the Upper Cretaceous 

deposits (e.g. the islands of Cres, Krk, Sv. Grgur, Prvic 

and Goli Otok, as wcll as on part of the Cicarija ML). 

Therefore, during further investigations special atten­

tion should be given to the palacogeographic aspect. 

Geologia CrOi1tica 49/1 

6. CONCLUSIONS 

On the basis of the presented data and their discus­
sion the following results importa nt fo r the interpreta­
tion of the geological evcnts which oecured during the 
Cretaceous and Tertiary in western Istr ia should be 
emphasised: 

I ) Near Sv. Lovrec previously unknown erosional 
relics of the Eocene Foramini feral limestone were 
discovered overlying Valanginian and Barrem ian 
limestones. 

2) The footwall of the relics of the Eocene Fora­
miniferal limes tone near Visnjan is composed of the 
peritidal mudstones and wackestone/packstones of 
Haute riv ian age. A s imilar situation occurs in the 
Kolone Cove SE of Rovinj, where the Eocene 
Foraminiferal limestone is in contact with the Hau­
terivian limestone. 

3) T ecton ic activ it y (i.e. re lative uplift caused by the 
gentle fo lding and/or faulting) and eustatic changes 
(i .e. the sea-level fall) has produced frequent emer­
sions of variable duration during the Lat e Jurass ic 
and Cretaceous: in the Kimmeridgian/Tithonian, 
Hauterivian, Barremian and Aptian/Albian. 

4) The emerged areas were inhabited by dinosaurs, 
during the s trati graph ic range from the Late Hau­
terivian to the Upper Cenomanian (at least), as ev i­
denced by rel ics of their footprints and bones. 

5) Facts stated in 1-4 were determined in the wider 
area of the western l strian anticline, and arc closely 
related to the timing of its formation and later relat­
ed geological events. 

6) Thc beginning of the formation of the structure took 
place earlier than in the Maastrich tian : it is dete r­
mined by the palaeotectonical parameters deter­
mined in the Hauterivian and Cenomanian, and reg­
istered in the Aptian and Albian. 

7) The orientation of the above mentioned palaeostruc­
tural clements formed by synsedimentary tectonical 
activity during the Early and Late Cretaceous of 
Istria is in agreement with the elements whose for­
mation was formerly attributed exclusively to the 
Maastrichtian age in Istria, as well as in the other 
regions of the Adriatic Carbonate Platform. 

8) Bauxites from the footwall of the Palaeogene lime­
stones were deposited in the palaeorelief of the 
Cenomanian and Albian limestones. This fact 
toge ther with the transgrcssivc nature o/" the Eocene 
Foraminiferal li mestones on the Valanginian, Hau ­
terivian, Barremian, Albian and Cenomanian 
deposits exclude the possibility of the continuous 
deposition of a complete Upper Cretaceous sequ­
ence, and its subsequent erosion prior to deposition 
of the Foraminiferal limestones, especially as there 
should have been eroded laterally different amounts 
of material (from 1.000 to 2.000 m) without any 
trace, and without any evidence of intense tectonics. 



Maticcc. Vlahovie. Velie & Tisljar: Eocene Limestones Overlying Lower Cret~ceous Deposits .. 

;;f(~n 
~ A; 

;t~~~ __ ~!~~-~~ ____ ~~ __ -L~~ 1 4 

±O Sea-lev()1 

==""==="'i",,'"-::~,-=""?'=c::c/ ±o Sea-level 

) ( 

±O Sea-level 

LEGEND: 

;t 5 

125 

Eocene 

o 

Santonian 

c 

Cenomanian 

B 

Neocomian 

A 

rig. S A schell1<1tic dmwing rcpresenting tile p;daeogeological dynamics of western htria during the Cretaceou~ and Palacogclll:.'. A) The initial 
stage of formation of the western ]strian structllre; B) Relation between tile shallow-water environments and thc land areas in the complex 
geomo rphology of the structure caused by tectonic uplift; C) Decrease of marine deposition during the extensive ernersion; D) Formation of 
the flyseh basin by the refolding of the Cretaceous anticli ne; Legend: I) Lower Cretaceous deposits: 2) Cenomanian deposits: 3) Turonian ­
Santonian deposits: 4) Palaeogene Foraminiferal limestones and flysch deposits: 5) Orientation of the regional stress during the Cretaceous 
lcc/ollic cycle: 6) Orientation of the regional stress during the Tertiary tectonic cycle. 



126 

Analysis and interpretation of the presented results 

facilitate the following conclusions on the paJaeogeo­
logical evolution of the western lstria: 

• The mutual relations of the Cretaceolls and Palaeo­

gene stratigraphic lInils , as well as tile otlier men­

riolleel data indicate lhal ill the central parI of the 
S{l"Uc/ure YOllnger Early Cretaceous and Late Creta ­

ceolls IInits were //O! deposited as a COf/sequence of 

the prolonged subaerial exposure. 

• The Loran/ian tec/ollic phase, which is in fhe Dinar­

ides attributed 10 be of the youngest Cretaceous 

(Maastrichtian) and oldest Palaeogene age , at least 
ill the area of the western IsfFian anticline repre ­

SCI/Is only one of the tectonic phases within the Cre­

taceOllS tectonic cycle, characterised by fhe same 

tectollic coordinates sillce fhe Neocomian. 

Acknowledgement 

This paper was written as a result of work undertak­
en for the Geological Map of the Republic of Croatia 

(scale I :50.000), financed by the Ministry of Science 

and Technology of the Republic of Croatia. We are 
gratcful for thc material support which has been provid­

ed by the Institute of Geology, Zagreb. Also, we are 

grateful 10 Dr. Vlasta COSOVIC for her determination 

and biostratigraphical interpretation of the Eocene lime­
stones and Dr. Branko SOKAC for his determination of 

fossil algae. We would especially like to thank Prof. Dr. 
Ivan BLASKOvIC, Dr. Bojan OGORELEC. Prof. Dr. 
Giovanni Battista CARULLl and Dr. Julie ROBSON 
for their suggestions, comments and critical reviews of 
the manuscript. 

Geologia Croatica 49/1 

6. REFERENCES 

BABIC, LJ., ZUPANIC. J. & JURACIC. M. (1995): 
Supply from an outer carbonate platform to the fore­
land basin of the Coastal Dinarides: the Pazin Fly­
sch Basin (Eocene, Croatia).- In: VLAHOVIC, I., 
VELIC, I. & SPARICA. M. (eds.): 1. hrvatski geo­
loski kongres (First Croatian Geological Congress), 
Zbornik radova (Procccdings), 1,43-45, Zagreb. 

DALLA vECCHIA, F.M. & TARLAO, A. (1995): 
Dinosaur Evidence in the Cretaceous of lstria 
(Croatia). - In: VLAHOVIC. I., VELIC, I. & SPA­
RICA, M. (eds.): 1. hrvatski geoloski kongres (First 
Croatian Geological Congress), Zbornik radova 
(Proceedings). I. 151-154. Zagreb. 

DROBNE. K. (1977): Alveolines paleogenes de la 
Slovcnie et de l 'Istrie.- Schwciz. PaHiont. Abh ., 99, 
174 p., Basel. 

GUi:Jc. I. & JELASKA. V. (1993): Upper Cenoman­
ian-Lower Turonian sea-level rise ancl its conse­
quences on the Adriatic-Dinaric carbonate plat­
form. - Geol. Rundsch. , 82. 676-686. 

MARINCIC. S. (1986): Fhs.- 5. skup sedimento loga 
JugosJ., Voclic ekskurzije , 27, Brioni. 

MARIN CIC, S. & MA TICEC, D. (1989): Kolapsne 
strukture u boksitnim jamama Istre (Collapse struc­
tures in bauxite pits of Istria). - Geol. vjesnik, 42, 
121-131, Zagreb. 

MARINCIC, S. & MA TICEC, D. (1991): Tektonika i 
kinematika deformacija na primjcru Istre (Tectonics 
and kinematic of deformations, an Istrian model). ­
Geol. vjesnik, 44, 257-268, Zagreb. 

MATICEC. D. (1994): Neotectonic deformalions in 
Western Istria, Croatia.- Geol. Croat., 47/2, 199-
204. 

POLSAK, A. (1967): Osnovna geoloska kart a SFRJ, 
list Pula 1:100.000. L 33-112.- Inst. geol. istra7 .. 
Zagreb (1963). Say. geol. zavod. Beograd. 

POLSAK. A & SIKIC. D. (1969): Osnovna geoloska 
kart a SFRJ, list Ravinj 1:100.000. L 33-100.-lnst. 
geol. istrai. Zagreb (1957-1963), Sav. geol. zayac!. 
Beograd. 

POLSAK, A. & SIKIC, D. (1973): Osnovna geoloska 
karta SFR.T. Tumai' za list Rovinj I: 100.000, L 33-
100 (Explanatory notes for the Rovinj sheet). - Inst. 
geol. istraz. Zagreb (1963), Say. geol. zavod , 
Beograd, 51 p. 

SIKIC, D., POLSAK. A. & MAGAS, N. (1969): 
Osnovna geoloska karta SFRJ, list Labin I: 100.000. 
L 33- 101.- Insl. geol. iSlraz. Zagreb (1958 1967), 
Sav. geo l. zavocl, Beograd. 

TISLJAR, J., VLAHOVIC. 1., MATICEC, D. & 
vELlC, 1. (1995): Platformni facijes i od gornjeg 
titona do gornjeg alba u zapaclnoj Istri i prijclaz u 



M:lticee, Vln.hovie, Velie & Tisljar: Eocene Limestone.~ Overlying Lower Cretaceous Deposits ... 127 

tempestitne, klinoformne i rudistne biolititne faci­
jese donjeg ccnomana u juznoj Istri (Ekskurzija B) 
(Platform facies from the Upper Tithonian to Upper 
Albian in western Istri a and transition into tem­
pestite, clinoform and rudist biolithite facies of the 
Lower Cenomanian in southern Istria (Excursion 
B )).· In: VLAHOVIC, I. & VELlC, 1. (eds.): 1. 
hrvatski geoloski kongres (First Croatian Geological 
Congrcss), Vodic ckskurzija (Excursion gui de­
book), 67·110, Zagreb. 

TUNIS, G., SPARICA, M. & VENTURINI, S. (1994): 
Lower Cretaceous Dinosaurs from Valle (lstria, 
Croatia): Stratigraphical, Sedimentological and 
Palaeoenviromental Problems. - 14th Internat ional 
Sedimentological Congress, Recife 1994, Abstracts, 
S5, 14·15, Recife. 

VELlC, I., TISLJAR, J. & SOKAC, B. (1989): The 
var iabil ity of thicknesses of the Barremian, Aptian 
and Albian carbonates as a consequence of chang­
ing depos itional environments and emersion in 
Western Istria (Croat ia, Yugoslavia).- Mem. Soc. 
Geol. It., 40 (1987), 209·218. 

VELIC, I. & VLAHOV IC, 1. (1994): Foraminiferal 
assemblages in the Cenomanian of the Buzet-Savu­
drija area (Northwestern Istria, Croatia) .- Oeo l. 
Croat., 47/1 , 25-43. 

VLAHOVIC, I. , TISLJAR, J. & VELIC, I. (1994): 
Influence of synsedimentary tectonics and eustatic 
changes on deposition of the Cenomanian platform 
carbonates in Istria (Western Croatia). - Geo logi c 
Medilcrraneenne, 21/3-4, 189·193. 

Manuscript received July 7, 1995. 
Revised manuscript accepted May 27,1996.