Nummulitins from flysch in surroundings of Ilirska Bistrica, southwest Slovenia

Described are nummulitins from four localities in surroundings of Ilirska Bistrica. They were found in flysch rocks of Lower Cuisian and Upper Cuisian age, and of Cuisian/ Lutetian transition.


Introduction
There were no detailed paleontologic investigations of nummulitins in the surroundings of Ilirska Bistrica till now with the exception of those near Podgrad (K h a n et al., 1975), where new forms Operculina marinellii similis K h a n & P a v l o v e c (at present Assilina marinellii similis), Nummulites brkiniensis K h a n & P a v l o v e c and N. postbearnensis K h a n & P a v l o v e c were determined. In addition occur in that loca- Geology of this area is best described in guidebook and geologic map of the sheet Ilirska Bistrica ([ i k i } et al., 1972, 1975). In guidebook the mentioned nummulitin species from various stratigraphic horizons are listed, and therefore also the determinations are not very reliable. A short description of geology of surroundings of Ilirska Bistrica was provided by P a v l o v e c and P l e n i~a r (1980,2000). East and northeastward from Ilirska Bistrica extend Cretaceous and Paleogene limestones, and on the other side, in Brkini, the flysch beds. Microfossils from a profile between Podgrad and [embije were examined by K h a n (1976,1977,1983). He determined the beginning of flysch deposition with basal marlstone at Ilirska Bistrica in Ilerdian, and in surroundings of Podgrad on southern side of Brkini in Cuisian only.
From the environs of Kute`evo and Trpane ( fig. 1) several specimens of nummulitins were sent by Franc Poklar from Podgraje near Ilirska Bistrica. Along with him slopes of Goli vrh (859 m), Kozlek (997 m) and Gradi{~e (874 m) Cretaceous, and above Zabi~e also Jurassic beds crop out. They are thrust over the flysch beds. In hills west of Trp~ane ( fig. 2, 3) occurs grey to dark grey marlstone, in places with thicker sandstone intercalations. In certain parts occur abundant pebbles. Marlstone is little resistant to erosion, therefore the weathering crust is thick and erosion intense with smaller slumps in the slopes. Stronger erosion phenomena marked in the detailed maps extend south of Trp~ane in the Ivan{~ek ravine between Golobinjek (534 m), Svibni hrib (572 m) and ^ikovka (504 m).
Also in slopes west and northwest of Kute`evo ( fig. 4) outcrops abundantly the partly slaty grey to brown marlstone and in places also sandstone. In its lower parts occur many pebbles up to 10 cm of size. Among them prevail limestones with moderate sandstone and chert. Especially on slopes on the marlstone surface erosion and small slumps are  Sl. 2. Nahajali{~e numulitin pri Trp~anah. fossils were collected also by Peter Valen-i~ from Trp~ane, Marko [ajn and by pupils of the Kute`evo elementary school. The localities were visited also by Dr. Vasja Miku` who furnished several fossils. A sample from Dolenjska Draga north of Dolenje was brought by Silvano Belu{i~ from Ilirska Bistrica. In this way several nummulitins from east of Ilirska Bistrica could have been first determined. Also in this place kindest thanks are extended to the mentioned persons for their valuable assistance in collecting the nummulitins. Unfortunatelly, the late S. Belu{i~ did not live to see this publication.
The small villages of Trp~ane and Kuteevo are situated in the Reka valley 7 to 8 km southeast of Ilirska Bistrica, or about 5 km northwest of Jel{ane. In the valley itself occur in part swampy Holocene alluvial deposits of river Reka and its affluents. Immediately above the flood plain flysch beds are exposed. Above Kute`evo and Trp~ane in developed. Nummulitins were collected west of Kute`evo. Beds are in places folded and faulted ( fig. 5).
At Dolnji Zemon occur partly marlstone with occurrences of smaller slumps, and partly mudstone and somewhat thicker beds of sandstone.
The nummulitin locality is situated in the ravine Dolenjska draga a kilometer and a half southeast of Mala Bukovica, west of Golobinjek, north of Stra`nica (577 m) and 2,5 km northwest of Jel{ane. Nummulitins occur in an intercalation of hard calcarenite.
In the entire area of mentioned nummulitin localities occur several presumed or established faults, mostly of the Dinaric direction ([ i k i } et al., 1972), and north and south of the Reka valley also a number of folds, synclines and anticlines.The complex structure is a consequence of pressure and thrusting of the Mt. Sne`nik massif. Owing to this geologic structure in individual parts the flysch beds of various ages are exposed.  Sl. 4. Nahajali{~e numulitin pri Kute'evem. ter star-like ridges, then dense round granules. Toward the external edge on the surface the whorl rim and septa are visible. Toward the center the test is bulged, just at center somewhat depressed, and it thins toward the external edge. The megalospheric generation measures around 5 mm. On the surface appear in the center several round granules, and toward the outer edge the internal structure with five whorls is distinctly visible. This Lower Cuisian species was found in Slovenia first. The test diameter is 2.2 mm, with 2.5 whorls that heighten rapidly. In the center are dense round thorns that are close to spirally disposed. On the external two whorls the thorns are strewn on vestiges of septa. In the lower part septa are almost level or only slightly concave. In the upper part they are strongly bent backward, and are sickle-shaped

Descriptions of nummulitins
In the Trp~ane locality this species is very rare. It lived in Lower Eocene, according to H o t t i n g e r (1977) and T o s q u e l l a & S e r r a -K i e l (1998) in Lower Cuisian. It was found at Guttaring (Kotar~e) in Carinthia, in Pyreneans, Betic Cordilleras and on Crimea. It was first found in Slovenia. This foraminifer is very rare in Dolenjska draga. Whorls heighten rapidly, septa are slightly concave and strewn with thorns. On the surface, granules are the most abundant in central part of the test that is somewhat thickened along the whorl edge. This form is very similar to subspecies Assilina marinellii similis (K h a n & P a v l o v e c ) (K h a n et al., 1975), but the difference with subspecies Ass. marinellii marinellii (Dainelli) is minimal. It is questionable whether the establishment of a new subspecies was justified, and whether the "subspecies" similis could be included into the variation range of the type. Also the possibility of closeness of the individual of Dolenjska draga to Lower Lutetian species Assilina praespira Douvillé cannot be excluded. These problems could be solved on the basis of more numerous and better preserved specimens.
Assilina marinellii marinellii is known from Middle Cuisian (H o t t i n g e r , 1977). Of same age is also Assilina marinellii similis (K h a n et al., 1975). With respect to subspecies Assilina maior maior Heim the locality Dolenjska draga can be attributed to the Upper Cuisian. With this, the life span of group Assilina marinellii is extended to the Middle and Upper Cuisian. The microspheric generation is about 20 mm, and the megalospheric around 8 mm across. On surface the frequent spiral ridges follow the whorl edge. Especially in central part the granules are dense, and toward the outer edge the internal structure becomes visible. Toward the central part tiny granules increasingly occur on the septal prolongements.
An individual from Dolenjska draga is of megalospheric generation that resembles in its equatorial section the transitory form Assilina laxispira-maior mentioned by S c h au b (1981,200) from Middle Cuisian near Buttrio in Friuli. However, the individuals of microspheric generation with test diameter above 20 mm seem too large for this form. Therefore also the foraminifers from Dolenjska draga are attributed to subspecies Assilina maior maior.
This subspecies is rather frequent, and was already found several times in Slovenia. It is especially abundant in two localities at Vipol`e in Gori{ka brda in Slovenia (C im e r m a n et al., 1974; P a v l o v e c & S i m -i~, 1999), which are now largely destroyed due to newly developed vineyards. Assilina maior maior is an Upper Cuisian species that was found in Friuli at Rosazzo (Ro`ac), on island of Krk in Croatia and elsewhere (S c h a u b , 1981).

Assilina cuvillieri S c h a u b , 1981
Pl. 1, fig. 3 The test of microspheric generation is thin, in the center somewhat concave. On the surface occur numerous round granules that are densest in the central part. Toward the external edge granules are disposed on septal prolongements and above the whorl edge. The test of megalospheric generation is more thickened in the center and has strong thorns. Toward the external edge thorns are fewer.
The species is Upper Cuisian. It was found among others also on the Krk island in Croatia and in Gori{ka brda in Slovenia (C im e r m a n et al. , 1974). Flat tests are in center somewhat thickened, some are a little concave. On the surface occur in the center either strong star-like ridges, or radial ridges and thorns that follow the internal structure across the entire test. Size of test is less than 10 mm and its thickness 2 to 2.3 mm. This species is rare at Dolnji Zemon.
Assilina suteri was found in the youngest Cuisian in Gori{ka brda in Slovenia and on the Krk island in Croatia. In other localities it is known from the base of Lutetian or from somewhat higher horizons of Lower Lutetian. The beds at Dolnji Zemon can be attributed to the youngest Cuisian, resp. to Cuisian-Lutetian transition. This form is very rare at Kute`evo. The test diameter is 9.8 mm, and thickness 3.4 mm. At the center, the test is somewhat thickened and just in the center slightly concave.The surface is covered by dense granules. Toward the external edge the septa and whorl edge are visible, and granules are strewn also on these elements and between them.The external edge of test is sharp.
The external structure of the Kute`evo specimen resembles more the species Assilina medanica than the related Assilina suteri. It differs from typical Assilina medanica by greater test thickness for which S c h a u b (1981) reported 1.6 to 2.5 mm.
Assilina medanica is an Upper Cuisian species, but was found also in Lower Lutetian beds. Its first find was reported from Vipol`e in Gori{ka brda, Slovenia. The test of megalospheric generation is small, about 4 mm in diameter. In the center occur several strong thorns, and toward the periphery extend slightly curved septal lines. The whorls heighten only gradually. Septa are slightly curved, and chambers are almost isometric. On the surface of the microspheric generation test occur in the center round, rather strong thorns. Near the external edge are relatively thin and almost straight septal lines. This subspecies was mentioned by S c h a u b (1981) from Lower and Middle Cuisian. It was found near Buttrio in Friuli, Italy.

Nummulites burdigalensis pergranulatus
Nummulites sp. Pl. 3, fig. 1, 2 Locality: Trp~ane The microspheric generation measures up to 11 mm. The test is lenticular with a rather sharp and somewhat wavy external edge. On the surface appear dense round granules. The internal 5 to 6 whorls heighten slowly, and afterwards they increase more rapidly. The total number of whorls is about 15. Septa are inclined and slightly curved. Chambers are for the most part isometric, but in external whorls, however, the length of some chambers exceeds their height.
The nummulite is similar especially by its surface granularity to species Nummulites friulanus S c h a u b . The nummulite from Trp~ane is, however, older. The subspecies Nummulites burdigalensis pergranulatus is smaller and displays on its surface less thicker granules than the specimens from Trpane. We consider the latter an intermediate form between  Thick lenticular tests measure 9.5 to 10.5 mm across and are 4.5 to 5.2 mm thick. The surface is strewn with numerous round granules. Inbetween slightly curved ridges are situated, well expressed in some individuals, and less expressed in others. On the 5 mm radius come 16 whorls that tend to lower, especially in the peripheral part. Chambers are lengthened toward the external edge, septa are inclined and slightly curved.
Nummulites friulanus is an Upper Cuisian species. In Slovenia it was found already, and is the most abundant in Gori{ka brda. It was named after Friuli where it was first detected at Rosazzo (Ro`ac). The test is thick, lenticular, about 10 mm in diameter and to 5.5 mm thick. The external edge is sharp. On surface occur curved septal lines. Granules in the central part are the most abundant, and they are less numerous toward the external edge of test. Whorls heighten slowly and regularly, the last ones tend to lower. Septa are inclined and slightly curved. Chambers in internal whorls are higher than long, or they are isometric, and lengthen somewhat in the external whorls.
S c h a u b (1981) described this form as Nummulites aff. lehneri from the Upper Cuisian beds at Haymana in Turkey. The original Nummulites lehneri Schaub is larger and lived in Lower Lutetian. For the form Nummulites aff. lehneri the surroundings of Ilirska Bistrica is the second known locality. Provided better and more abundant material a new species should be most probably described. The fossil is by all means a different form than the Lower Lutetian Nummulites cf. lehneri, mentioned from France by S c h a u b (1981) and S e r r a -K i e l (1984).

Nummulites pavloveci S c h a u b , 1981
Pl. 4, fig. 1 The test, about 10 mm in diameter, is lenticular and rather thick with a rounded external edge. On the surface are strongly curved septal lines. The whorls heighten quite regularly, although many of them are irregular. Chambers are chiefly isometric, and even of greater length than height. Septa are curved and especially in their upper part strongly drawn backwards.
This species is known from Lower Cuisian. Thin, in center gently thickened tests are at external edge somewhat wavy, and also the entire test is sometimes wavy. Size of tests is 13 to 15 mm, rarely even 17 to 19 mm, and thickness from 2.6 to 3.5 mm. On the surface occurs an abundance of irregularly arranged small thorns between which are radial, somewhat wavy ridges. On rare individuals pathologic marks can be seen that are probably a result of mechanical damages and later healing up of tests.
The species is known from Upper Cuisian, also in Friuli and on the Krk island, and from Lower Lutetian in Istria and elsewhere. Locality: Trp~ane A hardly 2 mm large nummulite has in the center a strong thorn. From it pass to-ward the external edge almost straight and dense septal lines that are near the external edge slightly thickened. The most similarity with it is shown by the nummulite on plate 48, figure 12 b (S c h a u b , 1981).

Nummulites pustulosus
Nummulites pustulosus is known from Lower and Middle Cuisian.
At Dolnji Zemon Assilina suteri and Nummulites aff. lehneri sensu S c h a u b 1981 were found. On this basis the flysch beds there are attributed to youngest Cuisian, or to the Cuisian-Lutetian transition.
Such diversity of flysch beds ages in the surroundings of Ilirska Bistrica is not surprising. It is the rather complex geology, especially near the overthrust of the Sne`nik massif, that resulted into various ages of the near-by localities of Dolenjska draga, Trep~ane and Kute`evo. K h a n (1976) pro-  , 1991). At Trep~ane now also the Lower Cuisian age of flysch beds of the Brkini basin was proved with nummulitins.