I 
GEOL. CROAT . I 50/1 I 33 - 48 I J 9 Figs. I I ZAGREB 1997 

The Development of the Eocene Platform Carbonates from 
Wells in the Middle Adriatic Off-Shore Area, Croatia 

Vlasta TAR! KOVACIC 

Key WOI-ds: Eocene, Platform carbonates, Wirelinc 
logs, Adriatic o IT-shore, Croatia. 

Abstract 
[n the Middle Adriatic deep off-shore wells th e following sedi­

mentary f:lCi cs ex isl: fenestral :H1d Charophyte limestone facies (X): 
facies of foraminiferal wackestone-packstone. ostracod marls and fine 
grained breccia cong lomerate (A): facies of foraminiferal packstonc­
grai nstone (B) and milio lidal mudstone-wackestone (C): fac ies of 
porous limestone?, grai nstone? (V): facies of fossi liferous mudstone­
p;lckstonc (D); alga l bOtlnd stonc/bindstonc and wackestone fac ies 
(E): facies o f the fOraminiferal mudstone-packstone (F); NlI/nll/IlIiTeS­

Di.H·Ot:ydillu flo;ttstone-pacbtone and g rainstone-r ud stone faci es 
(G). The sedi ment s were deposited close to the carbonat e platform 
marg in. Beds of facies X hav e an uncertain str<ltigrap hi c position; 
you nge r than the Cre\<leeous but older than the Cu i sian. A transgres­
sive sequence Ihal is composed of facies A, B, C and Y was formed 
during the Cuisian, where~\<; the others belong to Lutct ian (and Diar­
ritzian). At the end of the Middl e Eocene Lhey were tectonically com­
pressed and cove red by fl ysch deposits. Good stratigraphic correla­
tion between the wel ls along the Dinaric slfike strongly suggests lhat 
the facics are latcrally cxtens ivc in th is direction. Perpendicul ar to the 
trend they arc considerably reduced . Oil shows in the Kalc- I well 
orig inated from the Lower Cretaceous so urce roc ks (evaporite com­
plex). 

1. INTRODUCTION 

The Eocene platform carbonates, alt hough of rela­
tive ly limited extent in Ihe Adriatic off-shore, bccame 
an interesting explora tion projcct when some oil shows 
in the wells Jadran-3, Jadran-9 and Kale- l were discov­
ered. 

This work is a study of the sedimentary platform 
Cad es development ancl the cessation of platform condi­
tions during the Lower (Cu isian) and Midd le Eocene 
(Lutetian to Biarritizian). In the North and Middle Adri­
atic, the Eocene platform carbonates were drilled only 
in the wells Kate- I, Jadran-3, Kornati More-4, Jadran-9 
and Susak More- I. Fi g ure 1 shows the well locations 
together with the north-eastern part o f the Tertiary 
(Dugi Olok) Depress ion and the south-eastern part 01" 
the Islrian Plat form. 

INA - Induslrija \lane. Exploration and DeveJop merll, Subiccva 29, 
J IR-1OOOO Zagreb, Croatia. 

2. METHODOLOGY 

The interpretation 01" the Eocene carbonate platform 
facies is based on analysis of the wircline log facies 
compared with the geological information acquired dur­
ing drilling and by th e transformation of the physical 
charac teristics of the sedim ents (w ire line log facies) 
into geological entit ies (sedimentary fac ies). Thi s 
met hod was scientiricall y developed by Selley rrom 
1970 to 1985 and since then it has been widely used in 
the oil industry. espec ially as the bas is ror building 
facies models and reconstructions of sedimentary envi­
ronments. 

The wireline log faci es interpretation was carried 
out on the logs which primaril y reliect the lithological 
characteris tics of the obscrved sedimcnts, i.e. the natur­
a l radioactivity (gamma rays and spcetralog) and poros­
ity logs (neutron, density and acoustic logs). 

The tec hnique is primarily qualitative and re lics 
heavily on the visual identification or the coherent units. 
The cri teria used for separat ing the units depend s on the 
geological data acquired by drilling. There is no stan­
dard procedure for separating certai n wi rel ine log 
facies, although it wou ld be logical to separate the obvi­
o us cohercnt rocks first, and then in corre lation with 
neighbouring we ll s, g radually perform more dc tai led 
scp:.uution. 

The sedimentary fac ies interpretation is based on the 
detailed study of the cored intervals and sed imentologi­
ca l core descriptions according to the micro-a nalyses 
(litho- and biostratigraphic data). 

For the cored inte rvals the ir constituent sedimentary 
faci es we re de tennined and added to the app ropriate 
wirel ine log facies. For the wi reline log fac ies which 
were not co red, sedimentary racics were det e rmined 
from mud cuttings and by comparison with s imilar 
wire line log facies that were cored in the same or in the 
neighbouring well s. 

3. EOCENE CARBONATE FACIES IN 
THE KATE-I, JADRAN-3, KORNA TI MORE-4, 

JADRAN-9 AND SUSAK MORE-I WELLS 

The Eocene platform carbonates in the examined 
wells are subdivided into ten wire line log facies of con­
s islent intervals (X, A, B, C, Y, D , E, F, G and I-I). For 



• ,l 

each of the wireline log facies the geological infonna­
tion acquired by drilling, deteml ined the corresponding 
sedimentary facies. 

3.1. Facies X - sedimentary facies of fenestral and 
Charophyte limestone 

(salt and brackish marshes, tidal nat) 

This is the oldest Palaeogene facies deposited on the 
karst plane formed of different units of the Upper Cre­
taceous (Cenomanian to Maastrichtian), after emersion 
and eros ion during the Palaeocene. H is :lcarly shown 
on the wireline log diagrams by the high values of com­
pensated density log (from now on referred to as densi­
ty) 2.45 - 2.70 glcm', by the low values of compensated 
neutron log ( from now on referred to as porosity) 4-
J 0%, by low values of borehole compcnsated acoustic 
log (in further text acoustic) approx. 230·\0'(' slm (70 
mcs/f!) and by low radioactivity (in further text gamma 
ray intensity) 10-20 API. The thickncss va ries laterally 
from 7-17 m. 

Mud loggi ng iden tified the following lithologies: 
bauxitic ooids of tangential concentric construction and 
pe liti c c lay with abundant pyrite in Kornati More-4 
(Fig. 2), fenestral and Charophyte limestone with vugs 
fill ed with mosaic drusy calcite in Kate- I (Fig. 3), 
pyritic fenestral limestone in Jadran-9 (Fig. 4) and fen­
estral limestonc with desiccation cracks, ostracods and 
miliolids in Jadran-3 (Fig. 5). 

These sediments were deposited on a low energy 
tidal flat or salt and brackish marshes under anoxic con­
ditions. The proximity of the coast wi th beaches is typi­
fi ed by dcposits in the area of the Kornati MorcA well. 
Due to the lack of index fossils, it is imposs ibl e to 
determine the age of these sediments. 11 is certain that 
they represent a shon transgressive sequcncc beforc the 
Middle Cu isian (the approximate age of sed iments from 
the ncxt tran sgress ive cycle). If the transgression was 
caused by eustatic sea level rise, it could be the result of 
maximal flooding by the end of the lIerdian ( HAQ et 
aI., 1987). The subscq ucnt emcrsion until the next 
transgression was rela ti vely short, 1-2 million years. 

o , 

Geologia Cromie:! 50/1 

50km 

Fig. I Location map. 

3.2. Facies A - sedimentary facies of foraminiferal 
wackestone-packstone, marl with ostracods and 

fine-grained breccia conglomerate 
(coastal environment with repeated shaJlowing 

and emersions) 

Thc main wireline log characteristic of thi s facies is 
the very high gamma ray intensi ty. The gamma radia­
tion curve has the typical express ion easi ly spolled on 
all exam ined wells ("hot streak" marker), Thc gamma 
ray intensity is highest at the lower part of the interval, 
from 70 API in the Kate-l well lip to 220 API in the 
Susak More-I well (Figs. 3 and 6). In the upper part of 
the interval the valucs arc considerably lower, up to 50 
API. Spectra log analysis from Kate- I proved that the 
uremi c component has more influe nce than either the 
thorium or potassium radioactive group. Thc coal from 
the Lower Eocene mines in Rasa, 1st ria , also has an ura­
nium content up to 300 ppm (FERTL, 1979). This ura­
niulll enrichmelll should bc of the samc origin because 
the sediments arc of the samc agc and from closely 
related environments. According to the lit erature 
(FERTL, 1979) a high uranium level in carbonate sedi­
ments can indicate the presence of organic or phosphate 
rich deposits or permeable zones through which thcre is 
a circu lat ion of underground waters enriched in urani­
um salts. 

The density, porosity and acoustics values arc 
almost identical to the previous facies, except for the 
first few met res (Fig. 7). 'rhc hi gher porosity va lue, 
gamma ray intens ity , highe r speed or acoust ic wave 
sprcading and densi ty depend on the presence of clay 
and breccia-conglomerate in the argillaceous matrix. 

Facies A was studied in cores from the well s Jad­
ran-3 (Figs. 5 and II) from 1764-1766 m, and Jadran-9 
(Fig. 4) from 1324-1327.3 m. The lowest 10 e l11 of the 
core in Jadran-3 is a fine grained limcstone breccia con­
glomerate wit h weakly rounded clasts in a matrix of 
skeletal detritus. These are followed by o rganic rich 
limesto ne, ostracods marl with burrows, desiccation 
cracks and fenestral milolid-coskinolinid limestone. 
The lithofacies of foraminiferal wackestone-packstone 
limestone prevails. Fractures and intcrgranular porosity 



Tari KovaC:i~: The Developmenl of Ihe Eocenc Platform Carbonatcs from Wells., 

KORNATI MORE - 4 

20API GR 
rt-..J.... --~­

>-
~ AC 
~ 90msec/ft 

o 
~ 

120 
- ~ 

~. \ ' / I 

, E -

/ ~ \ 

~ 

o 
i? 

o 

~ 

LITHOLOGY 

\ 

8. 

f-----
7. 

I--

8. 

7. 

I--

z .. 
>-

w 

>-

6. ~ 

I--

5. 

3. 

1. 

z .. 
!!i 
" u 

o· 
o 

Q. 

Legend: 

Nummutitids 

Alveotinids 

v=::J Discocyclinids 

c::=:') Miliolids 

L1 Conical foraminifers 

&- Benthic foraminifers 

(y Planktonic torams 

J Algae 

@ Corals 

P Bryozoans 

35 

Echmids 

~'-...L? Shells' debris 

Rudis-ts 

Charophyta 

Microcodium 

Ostracods 

Dessication cracks 

Caliche 

Birds eyes 

Ooids 

I "-.;'110 I 1 '--hi 

Fig. 2 Scqucncc of Palaeogene carbonates in the deep well Komali Morc-4. Legend: I) facies of fenestra! and CharopfJy/rl limestone (X); salt 
and brackish marshes, tidal /lat cnvironment; 2) facies of foraminiferal wackestone-packstone, marl with ostracods and fille grainecl breccia 
conglomeratc (A): coastal environme nt with repeated shal lowing and emersions: 3) facies of foraminiferal packstone-grainstone limestone 
and miliolidal mudstone-wackestone limestone (8 and C); coastal env ironment with repeated shallowing and emersiOIlS: 4) facies of porous 
limestone - ?grainstonc (Y); ?beaches: 5) facies of fossi liferous mudstone-packstone limestone (D); shallow platform and mud mounds envi­
ronment; 6) facies of algal boundstone (bindslonc) and wackestone (E); platform margin buildups; 7) facies of the foraminiferal l1ludstone­
packstone (F): foreslopc environment: 8) facies of NlllillIlII!ites-Discocyciina floatstone-packstonc and grainstone-rudstone (0); foreslope 
environmcnt: 9) shallow marinc mudstone-wackestone; [0) shallow marine packstone-grainstone; II) core samples: 12) mud samples. 

arc filled with bitumen. The sed iments were deposited 
in a pericoastal environment with repeated shallowing 
and emersions. 

]n the Jadran-9 well core mierocodium and pisolitic 
wackestone-packstone alternate with some bauxite and 
fossiliferous packstone-wackestone with shell debris, 

bryozoans, red and green algae and benthic forami ­
nifers in argillaceous mudstone and caliche. Microcod i­
lim is developed by mycorrhizal calcification (symbio­
sis of fungi and cortical cel ls of the plant roots) and 
caliche typical of [hc limestonc paJacosoil (KLAPPA, 
1978) , so they often occur together in the sed iment. 



16 

E 

g 
o 
N 

o 
1\l 
N 

KATE - 1 

15 GR ~ 
f--..,j. --- - - - -- ....I... 

AC 
75 mcs/ft Sp 

1'- ~ 
.: ~ --
f -? 
~ ~G -~ , 

~ 
~, .-, 
> , F 
~ 

< ,---' 

~ F:2m 
\. ~ ~ , 

> 
~G -, , 

1 , , , I 
; , E 
, I , , . I , , 
~? 

J 

':. , 
{ , 

<' , 
'-" 

0 

V> 

'" LITHOLOGY 
~ .. 
~ .. 
V> 

-I 

:;i 

1 

I lev 

@ 

:1! 

-jp 

f-p 
'J-

.. I 
.1'&',., 

!z 

! 
;; '" " Z 

'" 
.. 

ISL. 

8. 

-

7. 

I- Z 

7. .. -& N 

I-
8. _. 

a: 
a: 

I- .. 
-
'" 6 . , 
z 

I- .. 
-
I-
W 

I-

5. " ~ 

3.-
z .. 

I- iii 
2 . B 
1 g 

- w 
~ 

3 . :. 

5 . 
z 
" - ;: 
z 
!.! 
a: 
l­
V> .. 
" '" 

Fig. 3 Sequence of Pa laeogene carbonates in the deep we ll Kate- I. 
For legend sec Fig. 2. 

Such facies indicates :1 coastal environme nt with varia­

lion s of the sea leve l over a low lying plain. Coas tal 

(supratidal) sed iments alternate wi th sed iments indica­
t ive o f highly reduc tive s wamps thai are seasonal ly 

JADRAN -9 

GR 

:I: 
I- Ae .. .. 
0 

0 

i 

0 
0 

'" 

Geologia C rO:l1ica 50/1 

I-
Z 

'" ~ 
LITHOLOGY ~ 

a: 
;; 
Z 
w 

7. 

8 . 

5 . 

3. 

2 . 

" .. 
I-
w 
l-

" ~ 

z .. 
'" 
" U 

~ 
z 
o z 
w 
V> 

Fig. 4 Sequence of Palaeogene carbonates in the deep well Jad .. "n-9 . 
For legend sec Fig. 2. 

dried and occasionally with marine mitotid limestone 
due 10 minor sea level rise (DAVIS, 1985). 

Geochemical studies of the core samples determined 

that anlOrphous huminil c/vi trinite kerogen (>95 % ) is 
the dominant form of organic matte r (Corg 0.26-
0.43 % ), and it is therefore assumed that it was de ve­
loped by the biodegradation or a te rres tria l p recursor. 
The deposits do not exhibi t the source rock characteris­
tics as the major part of the organi c mallcr has bee n 
oxidiscd (high HI) within the sed imentary environme nt. 
The maturation parameter T

U13X 
(407 -41 O°C ) indicates 

an especia lly low degree of thermal transformation, and 
the re fore these sed ime nts cannot be cons idered as the 
source rocks. 

Mud samples in ot her intervals or Kornali Morc-4 , 
Kate- I and Jadran-9 wells (Figs. 2, 3 and 4) havc s imi­
lar charac te ri s tics to thc rocks in the cored in tc rvals . 
The thickness of th is facies varies between 10-26111. 



T;Hi KovaCic: The Development orlhe Eocene Plalfonn Carbon~ tes from Well s ... 

~ 
>­.. 
w 
o 

o 
o 
~ 

o 
o ., 

JADRAN - 3 

10 API GR 60 U) 

---- - ----------~--- w 

AC 
9?mcs/ m 50 

~ .. 
"' '" '" 

LITHOLOGY 

:. 
w ,. 
z 
i1 
;; 
z 
w 

6 . 

5. 

w 
(!) 
« 

>­
w 
>­
::> 
~ 

z 
3 . '" 

<f> 

2 . 

1. Pc? 

z 
'" z 
o 
z 
W 
<f> 

Fig. 5 Sequence of Palaeogcne carbonates in the deep well Jadran-3. 
For legend see r ig. 2. 

Sed imentary faeies 10 which the sediments of the 
wirel ine log facies A belong to, are sediments of coastal 
plain wi th fresh water flow s, swamps that occasionally 
dry ou t, and the beaches that are flooded by the sha llow 
sea that fo rms shallow res tricted lagoons. 

Due to the lack of index fo ssils the age is roughly 
de term inat ed as Lower and /or Middl e Cuis ian on the 
basis o f Caskinolina sp. , Fallate//a sp. , Spirolina sp. , 
discorb ids, rOl alid s, sma ll miliolids , ostracod s and 
green algae, and because the sediments o f facies A are 
confo rmably overlain by younger sediments of a deter­
minable age without any sedimentation break. 

3.3. Facies Band C - sedimentary facies of 
foraminifera l packstone-grainstone (Facies B) and 

miliolid mudstone-wackestone (Facies C) 
(the t idal flat environment) 

This fac ies is composed by alternation of facies B 
and C in a ll the we ll s. The density , po ros ity and 
acoust ic logs show th e good correlation of the two 
facies in a ll wells except in the Kate- l well (Figs. 3 and 

I 
~ 
>­.. 
w 
o 

o 

~ 

SUSAK MORE - 1 

G R 

20API 120 (I) .J. ___ _ __ ....1. W 

100 .AC 
m$C/It 

~ 

5( ~ 

'" <f> 

LITHOLOGY 

T 

I 

REVERSE F LT 

>­z 

! 
~ 
w 

<f> 
~ 

'" o 
~ 
<f> 

I--
4. 

3. 

I--
2. 

37 

w z 
w 

g 
::; 
o , 
w 
Z 
w 

@ 

z 
'" iii 
'5 
() 

o· 
1. ~ 

.. 
<f> 

"' 

4 . 

-

3. 

I--
2 . 

1 . 

.. 
<f> 

"' 

z 
'" z 

! 
w 
() 

z 
'" <f> 
:; 
() 

() 

Fig. 6 Seq ucnce of Pal aeogene carbonat cs in the decp well Susak 
More-I . For legc nd sec Fi g. 2. 

8) where the exchanges are more frequent in relation to 
the thickness of both faci es. Porosity in faci es B varies 
from 1010 25%, density 2. 35-2.60 g/cm3 and acoustics 



38 Geologi:l Croalica 50/1 

2 

FACIES "A" ~\O'!. 

2.2 IADRAN -l( o) CO, C., 
(1174-11S!hn) 
XATB.I ( 0) 
(237S-2J"m) 25 

~ 2.4 

~ 
~ 

~C()~' ~ 2.6 C~~ .. 
~ 
'" 

2.8 

3 
-5 o 5 10 15 20 25 

CO:MPENSATED NEUTRON POROSITY (%) 

100 

0 

0 
0 F~CIES '''A'' 0 

90 

80 
0 

JADRAN-J ( 0 ) 
0 

(17S9-1774m) 
0 

0 
KATE-I Co) 
(2375-238Sm) 

~ • gg .. ;: 0 
·E~o~ ! o 0 , 

~; 

20 

o'V ", 
0 

10 

o 
so 60 70 80 90 100 110 120 

ACOUSTIC (~s I it) 

from 197-230.10.6 slm (60-70 mes/ fL ). The values of 
these parameters in the Susak Morc-l well (Fig. 6) arc 
not re liable because of the cavernous borehole, but the 
charac te ristics of the Band C faci es a rc still visible. 
The gamma ray curve cloes nol reflect the changes in 
these facie s in any of the wells. In the lower part of the 
interval the va lues arc hi gher between 30 and 70 API. 
In Lhe upper parL , Lhey do noL exceed 30 A PI uniLs. Only 
in the Susak More - 1 well the va lues arc very hi gh , 
among 50 and 100 API uniLs. 

The facies was cored only in the Jadran-9 well, but 
in the tectonicaly rcpcated section in the interval 1342-
1345.2 m. Bauxitc oolites point to emcrs ion and/or the 
vic inity of karstificd coast, while fo ssilifc rous wacke­
stone-packstonc and grainstone limestone with benthic 
foramin ifers and eeilinids, algae and shell debris indi-

30 

- -

130 140 

a 

b 

foi g.7 Facies A: a) cross pl ot response showi ng car­
bonate point di stribution; b) GR/AC cross plOl 
response. 

ca te high energy shallow water environment. Facics C 
was cored in Lhe inLerval 1029- 1032 m. Li ghL brown 
miliolid wackcslone-packs LOne alte rnates with dark 
grcy and brown fe nes tral wackestone with gastropods. 
Fencstrae arc fill ed wit h internal sed im ent and mosaic 
drusy ca lcite cement. Shallow karstified surfaces and 
geopctal fabr ics we re al so noted. T he environm en tal 
energy was low. The mud samples of the samc facies in 
the Ka tc-I well also contain ostracods and oncoids. 

BOLh raeies arc Lypieal for Lhe Lidal flaL , Lheir appear­
ance and development can be connected to thc a ltcrna­
ti on of the sed iments depositcd in tidal channels (facies 
B) wiLh Lhose from Lh e shelLered lagoons (ponds) of 
hi gher salinity (facies C). The regularity of the alterna­
tion or both fac ies in all the we ll s (exccpt thc Katc-l 
well ) is curious. It is impossible to determinc whether 



T"ri Kov;ti;ic: The Development of the Eocene PI::l!fonn Carbonatcs from Wells ... 39 

2 ,----- - - ----- - - ------, 

2.2 

'a 
~ 2.4 

~,,~ 
2.6 

~ 
2.8 

FACIES "B" 

JADRAN - 3 (.) 
(1730-1759m) 
KORNAll MORE _ 4 (.) 
(I690-1710lD) 

3 ,-__ . 
-5 o 5 10 15 20 25 

COMPENSATED NElITRON POROSITY (%) 

00 

90 

FACIES "B" 
80 

JADRAN-3 ( 0 ) 
(17S9-1774m) 

a 
30 

b 

1-

KORNATIMORE-4 <.) f--
(237S-238Sm) 

60 

. ":.. '. 
-'. 

30 \i~~~ 
20 -" ... 
10 

0 

40 '0 60 70 80 90 100 110 120 

ACOUSTIC (~S 1ft) 

they represen t shallowing upward cycles or sto rm tide 
deposits. 

Onl y in the the Kate- I well are facies Band C also 
recognised be low facies X (Pi gs. 3 and 17). According 
to LUCIe ( 1993) this prese nt s the only known 
Palaeocene tidal nat deposit in the Adriatic off-shore. 

The forami niferal association with Coskillolillo per­
pera HOTTINGER & DROBNE ancl Cilry.wlidil/a 
lIIakarskac (van SOEST), determined the age as Lower 
Eocene (Middle - Upper Cuisian). 

3.4. Facies Y - sedimentary facies of porous 
limestone - '!grainstone (? beaches) 

Facies Y was iso latcd only in the Susak More- l 
well (Fig. 6), on ly on the gamma ray and acollstic logs, 
because during the drilling at the depth of 775 m (in the 

1-

130 140 
Fig. R Facics 13 : a) cross pt ol response showi ng car­

bonale poinl dislri bulion; b) GR/AC c ross pial 
responsc. 

lOp of this facies), the com plete loss of mud occurred , 
and due to cavernous borehole the porosity and density 
values are invalid . 

As the well samples were not available the determi­
nat ion or the facies charac teristics and the sed imentary 
envi ronment was not possible. Although, [he physical 
characteristics of scdimcnts enable certain assumptions. 
The decrease of gamma radiation is visible as well as 
the increase in acoustic value in relation to the facies B 
in the base. Such charac teristi cs corespond to the 
po rOlls limestone (?grainstone) developed in the hi gh 
energy envjronmcnt , where the mud component was 
washed out. If that is the case, following the Walter 's 
low (WILSON , 1975) on the lateral and vcrtical 

changes of the facies, these deposits could be interpret­
ed as the beach sands deposited over the tidal fla t facies 



40 Geologia Cromie:! 50/1 

2 

FACIES "D" S\.0 1> 

2.2 
JADRAN -3(o) 
(1604-1 67Sm) 
KATE· I (0) 
(221S-2299m) 

'8 2.4 
~ 
~ 
~ 

~C\)), ~ 2.6 C~;!>." 
" S 
"' 

2.8 

3 L-____________________ ~~~~ 

~ 0 5 10 15 W ~ ~ 
a 

COMPENSATED NEumON POROSITY (%) 

80 FACIES "0" 

JADRAN - 3 ( 0) 
(1604-167Sm) 
KATE-! Co) 
(221S-2299m) 
KORNATIMORE-4 C, ) 
(IS7S-163Sm) 

,,~::, 
'F 0 

'0 60 70 80 90 100 110 

ACOUSTIC (~s I ft) 

13 and C presenting regrcsive part of the sequence. 

3.5. Facies D - sed imentary facies of fossiliferous 
mudstone - packstone limestone (the shallow 

phltform and mud mounds environment) 

120 

In the north-western part of the carbonate platform 
the sedimentary sequence ends wit h the emersion by 
the end or the Lower Eocene (facies Y in the S usak 
Morc- I well). In the other areas the sedimentat ion con­
tinues during the gradual sea level ri sco f-ac ies D fol ­
lows con formably on the facies B in the KOlllati More-
4, Kate- I, Jad ran -9 and Jadran-3 wells (Figs . 2, 3, 4, 5 
and 9). 

The lower part of (he interval is composed of sedi ­
ment s with porosity vary ing between 3-18%, density of 
2.50-2.65 g/em and aco List ics bct ween 197-230· 10.6 s/m 
(60 and 70 mes/h ). [n the upper part of the inte rv a l, 

130 

b 

Fig. 9 Facics D: a) cross pl ot response showi ng car-
14{) bonate poi nt di stri blltion: b) GR/AC c ross plO L 

responsc. 

which has been developed in a ll the wells except the 
Jadran-9 well , the sediments are of hi ghe r dens ity 
(2.60-2.70 g/cm), lower porosity ( 1-8%) and aeo List ics 
( 184- 197.10-6 s/m, i.e. 56-60 mes/ft ). Gamma ray inten­
si ty is low: 10-20 API. In the Jadran-9 well the thi ck­
ness of these sediments is 8-22 m, whi Ie e lsewhere is 
58-80 m. 

The fac ies has not bee n cored. Accord ing to the 
anal ys is of mud samples, m udsto ne, wackestone and 
packstone containing miliolicls, conica l and large 
foraminifers and shells and corals debris, were deposi­
ted in the subtidal zone beneath the normal wawe base 
on the shallow platform. The fra gments of coral s and 
she ll s probably originate from di stant shoals (facies E) 
or from the mud mounds. 

Tn the upper part of the facies D of the Jadran-3 well 
(Fig. 5), mostly in the mudstone and wackestone/Ooat-



'I\l ri Kov;lcic: '111e Developmelll of the Eocene PI:lIfonn C:Hbona l c.~ from Wells ... 

100 

90 

FACIES "E" 
80 -

KATE-I (.) 
(2168-221Sm) 

- KORNATIMORE - 4 (.) 
( ISIS-1S7Sm) 

30 

20 

-~-.~ - P' , ,. .. ~ . • ' 
\0 

o 
2.8 2.6 2.4 2.2 

DENSITY (glcm') 

stone, new faunal clcments appear: corals and plankto­
nic foraminifera. T hese sedim ents can be compared 
with the Illud hu mmocky cross lami nation in the rcef 
base (ELLOY , 1982) where they arc actually located. 

It is important that the foraminiferal community 
changes in this faci cs . NumJllulites sp., Opercu/il/(f sp., 
A ssilina sp., and Discocyc!illa sp. of Ihe Midd le Eocene 
(Lut etian) age appcar for thc first lim c. The boundary 
between thc Cui s ian and Lu tclian coincides wit h the 
change of facies Band C into facies D. 

3.6. Facies E - sedimentary facies of algal 
boundstone (bindstone) and wackestone 

(marginal platform buildups) 

The sedim ents of thi s facies arc developed in the 
Komati More-4, Kate- I and Jadran-3 wells (Figs. 2, 3, 
5 and 10). On the wi re- li nc logs the typical scrrated 
curvc shows acoustics 56-90 mcs/ft , po rosity 3-30 % 
and dens ity 2. 35-2.70 g/cm3

. The gamm a ray value is 
less than 10 API. 

'fh e faci es in Jadran-3 well was tcs ted by the mech­
anical core in the interval 1565-1565.3 m (Pi g. 12). 

Fi£. I I Ostracode mtt d)o,tone-wackes tone. facies A. Earl y Eocene 
(Cuisian). Jadran -3. 1764 m, 25X. 

41 

---
2 

Fig. 10 Facies E: GR/DEN cro ss plot response. 

The rock is classified as al ga l bound stone (bind ­
stone) and wackestone according to the classification of 
EMBRY & KLOVA N ( 1971 ). It con tain s large 
foramini fera (NulJIlJIlIlites, Discocyclill(l , Amphistegina 
and Operculina), fin e benthic foraminifers, planktoni c 
foraminifers , bryozoans , corals, she ll s, echinids and 
encrusting red algae. As only a small interval of the 
fac ies was tes ted by coring (30 cm), it is diffi cult to 
determine is that the truc rcc f o r some o ther k ind o f 
margi nal platform bui ldup. According to the reg ional 
position and the appearance on the se ismi c lines, and 
also to the vertical and lateral spreading of the consid­
ered faci es, it may be det ermined as the marg inal plat­
form buildup. 

The changeable porosity is typical for reefs and also 
for peri -reefal facies. The literature describes in detail 
the complex processes that des troy primary and/or [0 1111 

the secondary poros ity (LAPORTE, 1974; BAB IC & 
ZUPANIC, 1979; TOOM EY, 1981; ELLOY , 1982; 
SELLEY, 1985). In Komati MoreA accordin g 10 the 
Illud cuttings the sedime nt s are dolomitized (a lso 
expressed all the dens ity and porosity logs) . In the 
Kate- I we ll , the karst development and open active 

Fig. 12 N/lII/II/IlIi{l 'S-Lilllo{lwl/lllilllll bindstone- floatstonc, facies E, 
M iddle Eocene (Lute ti an). Jadrnn-3, 1565 m . 28X. 



42 

00 

90 I 

80 
FACIES "F" 

KATE- t (0) 
(2070-2168m) 
KORNATIMORE-4 <.) 
(1470-1515m) 

60 

30 

20 

+-~-0 

40 so 60 70 80 90 100 110 120 

ACOUSTIC (~s/ft) 

fracture systems are visible on the photo-electrical 
absorption curve (PEF). The rise or the curve value 
PEF from 5 (limestone) to 7-9 in a rew intervals was 
caused by baroid drilling mud infiltration. 

In the Jadran-3 well this facies is the final member 
of the carbonate succession. The sedi mentat ion contin­
ues with siliciclastic turbidites, in the deeper sedimenta­

ryenvironment. 

3.7. Facies F - sedimentary facies of the foramini­
feral mudstone-packstone (foresiope environment) 

Facies F overlies on the reefal limestone in the Kor­
nati More-4 and Kate-l wells (Figs. 2, 3 and 13). It 
appears in the Jadran-9 well (Fig. 4) between the two 
intervals of the facies G, while in the Kale-J well (Fig. 
3) it alternates with facies G. The wire-l ine log facies 
almost looks like facies D. Porosi ty varies between 1-
6%, density from 2.55-2.70 g/cm3 and acoustics appro­
ximately 60 mcs/ft. The value of gamma ray intensity 
doesn 't excecd 15 API units. 

Fig. 14 Di.H:ocydina grainstone-packstone, facies F, Middle Eocene 
(Lutetian), Jadran-9, 1445 Ill, 25X. 

Geologia Croatica 50/ 1 

130 140 

Fig. 13 Facies F: GR/AC cross plot response. 

This facies hasn't been cored. According to the mud 
samples (Fig. 14) there are foraminiferal mudstone, 
wackestone-floatstone and packstone with coralli­
nacean and bryozoan debris. Its thickness is 46-98 
meters. 

Sediments from this facies are of Lutetian age 
(Spilaerogypsil/a globula (REUS), ASlerigeril/a rOlula 
KAUFMANN, Diseoeyclil/a sella D' ARCHIAC, Lepi­
docyclina sp., Nummulites sp., Turborotalia cerroasu­
leI/sis possagl/oensis (TOUMARKINE & BOLLI), 
Globigerina sc/1I1i (BECKMANN». They developed on 
the very edge of the platform toward the slope and 
basin, and they are laterally and vertically (Waltcr' s 
Law) the first neighbouring member of facies E and G 
of the transgressive sequence. 

The main criterion for determining the sedimentary 
environment was the fossil contenl. Bioclastic deposits 
in which the association of Discocyclina, Nummulites, 
Asterieyclilla and Sphacrogipsina dominate, with the 
significant presence of planktonic foraminifers, 
undoubtedly shows the foreslope and toe of slope envi-

Fig. [5 NllliIlIllllites-Discocycfina grainstone, facies G, Middle Eo­
cene (Lutctian), Jadran-9, 92 [ 111, 28X. 



Tari Kovacic: '111e Dc"clopmClll of the Eocene Pl:Ltfonn Caroon;llcs frolll Wells ... 

ronm en t beneath the wave base (B IGNOT, 1972; 
GHOSE, 1977; DROBNE et aI., J 991). 

3.8. Facies G - sedimentary faci es of Nu mmulites­
Discocyclillo floatstone-packstone and 

grainstone-rudstone (open platform shoals) 

Facies G overlies facies D in the Jadran-9 well (Fig. 
4). In Kornati MoreA and Kate-l wel ls (Figs. 2 and 3) 
it slicceeds facies F. In the Kornati More- I and Jadran-
9 wells it cyclically alternates facies F. 

The wire-line log characterist ics or fac ies G are 
poros it y of 3-10% in the Kate-I well , up to 25% in 
Kornati Mo re-4 we ll and up to 19% in the Jad ran-9 

well. The density var ies from 2.35-2.55 g/cm3 and 
acoust ics from 164- 197· 10 " s/m (50-60 mes/ft) . Gam­

ma r3Y intensity is approximatc ly 10 API. 
Facies G was studied in mechan ica l cores in Kate-! 

well between 2028-2046 m. According to the lithofa­
cies and sedimentological interpre tation the rock is 

composcd of NtllIlI1l11lites-D iscocyclhw noatstone/ 
packstone wi th occasionally hi gher con ten t of corall i­

naceans and bryozoans and fragments or ech inoderms 
and shells. The matrix contains fine-grained fossil frag­
ments and carbonatc mud, and rarcly mosa ic drusy cal­
ci te cement. Grainstone/rudstone typcs appear very 
often. Primary intraskeletal porosity is hi gh but it was 
diminished because o f the ceme ntation of intraskeietai 
cavities. Oil shows are connected with frac tures or sty­

lolitic su rface s and tec tonic fabrics wit h variable 
impregnation of the surrounding rock, especially where 
there arc dissolution hol es developed. Limestone of this 
fac ies was sed ime nt ed in the open piali'orm shallow 
water environment. 

In the ladran ~9 well, the same fac ies was s tudied 

be tween 915-92 1 m. According to pet rograph ic and 
lithological ana lyses, the rock is forami nifera l grai n­
stone-packstone (Pig. 15) and occasionally glauconitic. 
Because of the high energy environment, there are only 
a few planktonic foraminifera, whi le large foraminifers 
(mostly NUII/IIII/lires) are abundant. 

In the vertical sequence, the sed iments of facies G 
in Ihe wells Kale- ! , Kornati More-4 and Jadran-9 
aggradationally alt ernate with fac ies F o f the forereef 
environment, like the re fl ection of platform pu lsi ng 
before its final drowning uncler the s ilic iclastic flysch 
deposits. Sedimen ts of the facies G arc of the Lutetian 
age, and in the Kate- I well they are somewhat younger 
- Lutetian to I3iarritzian (Operclf/illa biaricensis 
OPPENHEIM, NII/mlll/lires lIIi//ecapl/f I30UBEE, NllIIl­

/lllIlires dll}i'ello)'i D' ARCHIAC & HElM E). 

4. lJISCUSSION 

4.1. Co .... elation in Wells 

A schemat ic correlation cross secti on (Pig. 16) 
shows the extent of the considered deposi ts along the 

43 

Dinaric st ructural trend, from the Susak More- l well in 
the north-west to the Kate - I well in the sou th ~eas t. 

They represent the older (carbonate) part of the trans­
gress ive megasequence of the Palaeogene and Neogene 
beds. 

Facies X, A, B and C a rc easi ly corrclatable ac ross 
a ll the we ll s. They were deposi ted in the coastal e nvi­
ronment (facies X and A), and in the tidal nat (facies B 
and C). In the Susak More-l well area, the sedimen tary 
sequence of th e Eocene carbonates was int errupted a t 
the beginning or the Lutetian because of the uplifting of 
the ca rbonate platform , caus ing the emersion which 
lasted till the e nd of the Upper Eocene, when the depo­
si tion of carbonate sediments continues again. The sed i­
me nts of the Upper C re taceo us, Eocene and Lower 
O ligocene were repeated twice in the well due to a 
reve rse fault at the depth of approx imately 945 m. The 
to ta l thi ckness of the Eocene sequence in the th rus ted 
part is 140 m and in the autocht hon 142 m. 

Toward the south and south-cas t the res t of the car­
bonate plat form was oscillating and slow ly drown ing, 
wit h the te nde ncy of increasing thickness or regarded 
dcposits. The transgressive sequence continues through 
the Luteti an with fac ies D, E, F and G, and the env iron­
men t changes from int ernal shallow platform toward 
platform edge. The thicknesses oj" the Lutetian depos its 
in Jadran-9 well arc 276, 132 and 157 m (tecton ica lly 
repeated sequcnces), in the Jadran-3 well is 288 111 , 

in Kornati More-4 we ll 369 111 , and in the Kate- I well 

395 m. 
In the Jadran-3 well area fac ies E (p latform marg in 

bu il dup) completes the ca lcareolls part of the transgres­
sive mcgaseq uence, wh ich continues with fly sch sedi­
ment ation. Facies G and F in the ladran-9, Kornati 
MoreA and Kate-l wells arc repeated cyclically. Shoals 
or open sha llow waters pass in to sedime nts of the fo re­
reef e nvi ro nme nt. Such an a lte rnation of facies is the 
result o f multiple, rela tive osc illa tions of sea level (Pig. 
17) that do not correspond wit h the eustat ic c urve of the 
sea level change (HAQ e t a I. , 1987) . Thi s reflects the 
pulsing of the platform before its fin a l drowni ng 
(SCIILAGER , 1981) because of the subsidence in front 
of the growing thrust structures of the Dinaridcs in the 
East. 

Because of fo ld ing ( recumbent fold ) and thrusting, 
in the Jadran-9 well, the same Palaeogene earbonale 
sediments were drilled in three intervals, with the mid­
dle interval being inverse. In all three inlcrvals the 
sequence of facies from X to G is identical. The thi ck~ 
ness of the inverted intcrval (132 m) is smaller in rela­
lion to the other two intervals because of the overbur­
den compaction and the structural dip of deposits. 

4.2. Correlation wHh On-shore Sediments 

According to their facia l characteristics, off-shore 
facie s X, A, and B can be com pared to the Liburnian 
and miliolidal limestone (SIKIC & POLSAK, 1973; 
BIG NOT, 1972; DROBNE, 1979) in l stria (Fig. 17). 



44 

SUSAK MORE - 1 
GR 

III 

= 2 

JAORAN-3 
GR 

L E 

~ 3 

8 4 

KORNATI MOR E - 4 

GR 

G E N 0 ' 

[E • . ,@.: 5 
o • 0' 

.IIJ ~ 6 

Geologia Croatica 50/1 

KA TE · 1 

GR 

D 7 • - - - - -

8 

o 50 100 150 m 

VERTICAL SCALE 

HORIZONTAL : NOT IN SCALE 

Fig. 16 Facies display: I) perit idal deposits: 2) coastHl deposi ts; 3) lidal flat deposits: 4) shallow platform deposi ts: 5) ope n platform shoals: 
6) ?bcach deposits: 7) platform margin bu ildups: 8) foreslopc deposits: 9) fl ysc h. 

However on the Koromacno cape in the base or the 
Li bu rni an sedi ments, there are poiimiclic brecc ia COIl ­
g lomerates 15 In thick, that arc also in a transgress ive 
relations hi p to the Upper Cretaceous limes tone. The 
breccia conglomerate is complete ly ullsorted, and CO I1 -

tains met re, c1ccimetre and centimetre sized c lasts of the 
Cre taceous and Pa laeocene (Kozina type) lim estone, 
and la rge c lasts of thick dark red and orange ca lc it e 
veins in the calcarenite matrix. 

O n the Los inj island, in the base of the miliolid 
(m udstonc-wackcstonc and packstone-grainstone) lime­
stone, the re a re al so transgressive breccias, approx i­
mately I mthick, with clasts of Cretaccotls limestone. 

The posit ion o f the breccia conglomerate is ident ical 
1'01' bot h o utc rops, so it is poss ible that they were 
fonned during the same event as the facies X in the off­
shore Ad riat ic. 

On the islands of Pasman , Ugljan and Kornati the 
facie s 1\, Band Care reduccd to a thickness of 3 m. 
MAMUZIC & NEDE LA- DEVIDE (1973) describe this 
as a tran sg ress ion ex pressed by basa l brecc ias in the 
" terra rossa" or recl c lay matrix up to 20 cm thick. The 
unconformity is almost unnoticeable. Brown platy lime­
stone that is similar to the Liburnian beds, with abu n­
dant small gastropods and mil iolids is depos ited on this 
transgress ive mate ri al. Even this level is not thicke r 

than 20 cm. The follo wing 2.5 m consis ts o f light 
brown, sli ghtly chal ky limestone w ith mili ol ids and 
some gastropods. There is a similar development of the 
same sediments on the islands of Ugljan and Losinj. 

The transgressive contact between the C re taceous 
and Eocene in the Ravni Kotari area is characterised by 
a karstified surface with bauxite or by supratidal fenes­
tral and intertidal miliolid limestone virtually concor­
dant with the underlying depos it s (D ROBNE e t a I. , 
1991); so fac ies X and A arc reduced (Fig. 18) . Facies 
Band C arc of similar thickness to those [rom the Jad­
ran-9 well (approx. lOO m). Alveoli na and Nummulites 
limestone o[ the Midd le Eocene, by the ir sed imentolog­
ica l and biostratigraphic characte ri s ti cs, can be com­
pa red with the sedimcnts of fac ies D, F and G in the 
off-shore. 

Platform margin lim estone in the we ll s Jadran-3 , 
Komati More-4 and Kate- I (Figs. 17 and 19) is devel­
oped on the very western edge of the carbonat e plat­
form. The scarse cored samples of th e wire lin e log 
facies on the buildup , well expressed on the seimic 
cross sections , do not a llow dete rminati o n of th e reef 
sens i/ striClO. Rccently publi shed papers (DRAGI­
CEV IC e t aI., 1992) and well dat a fro lll the Sou thern 
Adriatic indicate that the ree fs are not the exotic c le­
men ts in that area. In the Jadra n-3 well the pl at form 



Tari KovaCi~: The Development of the Eocene Platfonll Carbonates from WeilL. 

,; EUSTATIC CURVE WE L L S , 200 100 0 SM·l ,·3 KM · 4 '"' 
" --

-
- -

•• - -

• .. • z 
• z u 
0 • • 

0 ,. 0 

• 
IC , 

KATE · l 

-

, 

45 

OUTCROPS 
I.Korometno2.Lotinj ).SlIba 4 . U"Jan S .hnkovac II . Skt.din 

_-~I.:,I~ , 
• -• e:c.5 x ~X~X RS!ID x~ x 

? 
~XI~XI (:UJD x 1 

55 • 

6. 

6' 

THANETIAN 

• 
~ 
u 110.2 - ----- -

~ 
~ DANIAN : 

II .4 H 61111.1981. 

~B"C 
? 

~6'C 
, 
~B"C 

Fig. 17 Corrclation o f the on-shore and off-shore deposits. Legen<.l : X) perit idal deposits; XI) subfacies of the facies X in the outcrops: A) 

coasta l deposits: B+C) tidal nat deposits: D) shall ow plalfonn deposits; E) platfonn margin bui ldups: F) fo reslopc deposits: G) open plat­
form shoals: Y) ?beach deposits. 

margin was drowncd during the LUlctian, slightly earli ­
er than in other wells, because of the sudden tectoni c 
subsidcnce. At the same time in the Kornati More-4 and 
Kate- I wells, buildups first migrate toward the land in 
prograding transgression, and then they were replaced 
by shoals that indicate the relative shallowing or the sea 
level (tcc tonic uplift). 

Drowning or the platform beneath the fly sch 
depos it s is timed by nannofossils at the upper part or 
the Middle Lutetian: NP~15/16 nan nofoss il zone in 
(stria, in Ravni Kotari somewhat laler (NP~ 16) and in 
the Split area NP- 17 (BENIC, 1991). Therefore the ear­
bonale sed imcnts or .I3iarritzian age in the Kate- I well 
can be compared onl y to the sedi ment s sout h of the 
Krka rive r (in the surroundings of Skradin), and Sou th ~ 

ern Dalmatia (Peljesac and Cavtat). 

4.3. Petroleum potential 

In the Eocene limestone oj" the Katc ~ I well o il 
shows were traced in small intervals be tween 2020-
5630 m. In the considered sequence of the Eocene lime­
stone, hyd rocarbon shows occur in the intervals 2020-
2086 III and 2340-245 0 m. Part of the interval frolll 
2394~2450 m is of Crctaeeous age. The rese rvoir char­
actcris ti cs were primarily good (facies G) , but they 
were com ple tely destroyed by diagene tic processes. 
The oil appears in poorly connected fractures and vugs 
(secondary, frac tu J"C and "vuggy porosity"). 

Geochem ical analyses of the oil proved the presence 
o f su lphur (6-6.8%), and domination of n ~aJkanes . The 
pristane/phitane ratio is less than 1. The precursor is lhe 
ke roge ne type 11, lipids of algal and bacterial origi n 
deposited in a highly reductive environment. The oil 
from the Eocene limestone is characterised by "napht­
eni e hump" on the gas chromatograph, which is not 
presellt in Ihe deeper intervals of the well. This is 
ex plained by the lower kalagenctie degree or transfor~ 

mation or by possible oil degradation compared to the 
mature katagenet ic degree of trans forn1ation evaluated 
in the oil from deeper parts of the well. 

It is certain that the oil does not originate from the 
Eocene limestone of facies A. The organ ic matter in the 
facies A originates from kerogen type III which is dom~ 
inatcd by amorphous huminite/v itrinite or a tcrres trial 
precursor in the immaturc stage of the rmal transronna~ 

tion. In thc Jadran-9 and Jadran-3 wells, becausc of the 
cond ition s in the sedi mentary environment (peritidal 
cnvironmen t with occasional bracki sh wate r), most of 
the organic matter is ox id ised. 

However, in the Cretaceous sediments in the J adran ~ 

9, Jadran~3 and Kate-I well s sourec rocks were detcr~ 
mined that are in the early stage of the the rmal katage~ 
netic transformation (the beginning of the oil window) 
that generate oil. The Upper Cretaceous laminated 
mudstone of limited extcnt and thickness were deposit~ 
ed in the anoxic lagoons and conta in heavy isotopes 
(DC = 22-25%) and kerogen type I and 11. The precur~ 
sor is the algal~bacterial organi c matter of marine origin 
from a very rcduced environment, confirmed by the 
presence of heavy isotopes. The rock is also immature. 

The Lower Cretaceous source rocks contain kero­
gene type II and subordinately type I, in the early stage 
of ka tagenctic transformation. Organic rich lami nated 
stromatolit ic mudstone was depos ited in lagoons of 
hi gher sali nity and sabkhas. Thi s is confirmed by the 
pristane/phitane ratio which is lower than 1, the pres­
ence of sulphur rich asphaJtene and by heavy isotopes 
C ~C == 22%). On the gas chromatogram there is also a 
charac teri st ic " naphtenic hump", the same as ror the oil 
from Eocene reservoirs. 

Com paring the characteri stics of source rocks and 
oil , it is possible to conclude that oil has migrated into 
the a rea of Katc- l well from estimated so urce rocks of 
the Lower Cretaceous evaporite-carbonate beds. 



46 

-"- -
-"- -"-- -"-

~....'L-i:..::J.._ 

.JL .JL. ....lL. ....:L 

-"- -"- -"-
"" ,, --_ e 

SM·1 

e_ 

KM·4 

o 

Gcologj<l Croalic:l 5011 

Fig. 1 ~ Palaeogeographic map in Lower and Middle Cuisi<lll, faci es A. Legend: 1) peritidal deposits: 2) land. Pos it ion of the OLJICrops from lhe 
Fig. 17 afC keyed by numbers . 

1 

-"- ~ ~ 
L. .JL ~ ~_ 

..:.t.. ,.::L. ...!.t.. -.101.... 

~....I£....:f.. -""- ... 

....lL. ..>L. ...:>L ............. 

L.. ...:L. ....lL...x. 

..x.. SM-1- .....IoL.. ->L. 
L....:.L ~ $... 

.....\l.. -"4 ...;L .:L 

~ -"-

~2 

o SOkm 
-~~~~ ... 

3 

Fig. 19 Palaeogeograph ic map of LUlctian , faci es E, F and G. Legend: I) shoals; 2) forcslopc; 3) plalform margi n buildups; 4) land; 5) slope. 
Position of IIle outcrop from the Fig. 17 arc keyed by numbers. 

5. SUMMARY 

The paper is a comprehens ive study of the facies 
characteri stics of the Eocene Carbonate beds found in 
the Ce ntral Adriat ic wells: Kate-I, Iadran-3, Kornali 
More-I , Jadran -9, and Susak More-I. 

Considering wireline log analysis it has been possi­
ble to identi fy the wirclinc log-hlCics X, A, B, C, Y, D, 
E, P, G and H. The relevant sedimentary facie s have 
been de fined based on geo log ical and drilling data -
analysis of conventional cores and mud cllttings. 

Facies X, characterised by tidal flat sediments, rep-



Tari KovaCic: The Development of lhc Eocene Phufoml Carbon:l1es from Wells ... 

resents the firs t brief e pi sode te rminated by emersion. 

Facies A is thc first member of thc second major trans­
g ress ive sequence with which eventu a ll y te rminates 

development of the Adria tic (Dinari c) carbonate plat ­
form. It begins w ith a s treak m arke r horizon within a 

sedimentary fa c ies cha rac te rised by coas ta l lagoons, 
marshes and beaches. Cyclic alterna tion of Band C 
facies is cha racte ri stic for the tidal flat. Facies Y is the 

fin al membe r of the analysed sequence o f beds on the 
uplifted lstrian platform. Simultaneously, the carbonate 

p latform g radua ll y subsi ded to the south -east (D 
facies) . With furthe r transg ressions environment s 
become more dis tal , thus the fin a l membe rs o f the car­

bona te seque nce are formed by barrier bars, buildups 

and fores lope deposits ( faci es E, r +G). 
The s tudied beds have been affec ted by tangential 

tec toni c eve nt s at the e nd of the Eoccne pe riod. As a 

result of rolding ancl thru sting, the eas tc rn part of the 

studied area is upl ifted , wh ile the weste rn is lowered , 
thus form ing the Dugi Otok depression which has been 

fill ed with fl ysc h and flyschlike depos it s du ring the 

younger Palaeogene and in Miocene. 
Beds of the fac ies X have an uncertain s tratig raphic 

position, younger than the CrClaceouS but o lclc r than the 

Cuisian. Tran sg ress ive sequence fro111 A to Y faci es 

was form ed during C ui sian, whereas the others belong 
to the Lute tian (and Biarritzian). 

In corre lation with surface outcrops the synchronous 

beds, along the Dinaric strike show an al most ident ical 
deve lopment of the scdime ntary e nvi ronment regardless 
of how di stant these Illay be (the arca of Labin in Istria 
and the we ll s ill the Adriatic offshore) . Much closer 

sedilllen ts on Ihe Komal i islands and in Ravni Kotar 
outcropping in a perpendicular direc tion to the Dinar­

ides arc d iffe rc nt from the offshore sediments both with 
regard to composition and thickness. 

Acknowledgement 

The autho r wishcs to thank to the INA's Directory 
having perm itted thc publication o f this study and to G. 
BU RG EO IS , E. BALAZ, D. STANKOV IC, D. LUCIC , 

G. BARIC, J. T IS LJ AR and K. DROBNE, whose pa l­
aeontological, sedimento logical and geochemical analy­
ses were L1 sed in thi s paper. The author is espec ially 
grate ful to D. SA RTO RIO and S . VENTUR INI frolll 

AG IP S.p.A. who kindly reviewed the manuscript and 
provided many val ua bl e sugges ti on s. The specia l 
thanks to I. VU LAMA and D. BALIC who c reated 

crossplol displays. 

47 

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Manuscript received March 3, 1995. 
Revised manuscript accepted September 11, 1996.