Sedimentary characteristics and source of loess in Baranja (eastern Croatia)

Adriano Banaka*, Davor Pavelićb, Marijan Kovačićc, Oleg Mandicd

aCroatian Geological Survey, Department for Geology, Sachsova 2, HR-10000 Zagreb, Croatia

bFaculty of Mining, Geology and Petroleum Engineering, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia

cFaculty of Science, Department of Mineralogy and Petrology, University of Zagreb, Horvatovac 95, HR-10000 Zagreb, Croatia

dNatural History Museum Vienna, Department of Geology and Paleontology, Burgring 7, A-1010, Wien, Austria

*Corresponding author. Tel.: +385 1 6160 708; fax: +385 1 6160 799.

E-mail address: abanak@hgi-cgs.hr (A.Banak).

Abstract

Loess is terrestrial clastic sediment, composed dominantly of silt-sized particles formed by the accumulation of wind-blown dust. It is usually inter-bedded with soil horizons forming loess-palaeosol successions (LPS). Thickest LPS in Croatia are found in Baranja, region bounded with two big rivers, the Danube and the Drava. The results of grain-size and modal analysis provide information about source material and wind direction in different time periods during Pleistocene. Grain-size distribution is in good accordance with other loess localities in the Pannonian Basin. Garnet, epidote and amphibole mineral group are most abundant heavy minerals in samples of Danube River sediment. Comparing heavy mineral assemblage (HMF) from southern and northern LPS with that data, it is obvious that main source area for loess in Baranja is from Danube flood plain sediments. Main transport direction was from North or North-West. Nevertheless the higher concentration of amphiboles in southern and northern LPS (mean 26.3% in HMF) then in the Danube plain suggests additional source area. Western Carpathians with Neogene calc-alkaline volcanic rocks is major source for amphiboles. Alternatively those minerals could be from locally exposed volcanic and metamorphic rocks of the southward Slavonian Mts. Mt. Krndija and Mt. Papuk, which are closest to Baranja of all Slavonian Mts., consist of amphibolites. In that case, small amount of silt material for Baranja loess would be transported by WSW winds. Results obtained from sedimentological and SEM analyses show fairly good congruence with results from other LPS in the Pannonian Basin, with some differences in mineral composition which imply diversity and shifting of source area for Baranja loess during Late Pleistocene.

Key words: loess, Baranja, aeolian, heavy mineral fraction, quartz, SEM images

1.Introduction

Quaternary sediments are widespread in Croatia. They cover about 35.7% of the Croatian teritory (Bognar, 1976). Baranja, region in Eastern part of Croatia (Fig. 1) is almost completely covered with Quaternary sediments (Pikija & Šikić, 1991). Special place within,

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regarding the origin, holds loess and it's derivatives. Loess is terrestrial clastic sediment, composed predominantly of silt-size particles, formed by the accumulation of wind-blown dust (Pye, 1995).

Fig. 1. Map showing the position of Croatia, Baranja and two investigated loess profiles at slopes Bansko brdo hill.

One of the most specific characteristcs of loess is grain size distribution of particles. Most authors (Bognar, 1976; Nemecz et al., 2000; Pecsi, 1990; Smalley, 1966b; Smalley et al.,

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2005; Wright, 1995, 2001) agree that typical loess has grain size distribution in range 20-60 μm, which corelates with silt-size grains. Origin of those silt size particles and mechanism of it's transport is the main question in over one century of loess exploration. Two main thesis which are opposite-pedogenetic and aeolian, describe formation of thick loess deposits. First one emphasizes diagentic processes in silty material as beeing crucial in loess formation, while second one favors aeolian transport of silt-size particles. The aim of this study is to determine source area for loess in Baranja by identifying mineral composition of heavy mineral fraction and morphology of quartz grains. Geochemical and mineralogical bulk loess sediment analyses along parts of the Danube in NE and E Romania have pointed out that the main sediment for loess deposits was transported by winds from a NNW/NNE direction, indicating forcing by northerly winds from the Fennoscandian ice sheet (Buggle et al., 2008). Bokhorst et al. (2011) suggest a domination of western winds during the Early and Middle Pleniglacial in central and eastern Europe, while the Late Pleniglacial was dominated by NW or northern winds. Additionally this paper will propose a complex, five-phase process necessary for thick loess formation.

2. Geological setting

Geology of Baranja (Fig. 2) is simple at the surface, consisting of dominantly Pleistocene and Holocene sediments, with some outcrops of Miocene igneous rocks, limestones and marls (CGS, 2009). Holocene sediments are aluvial and marsh gravel, sand and silt. Pleistocene sediments are dominantly loess, loess-like sediment and flood plain sediments. Only high ground in Baranja region is Bansko brdo hill (244 m asl), an tectonic complex horst, situated in northern part of region, stretching 20 km in NE-SW direction and reaching banks of Danube river. Combination of active neotectonics (Hećimović, 1991) and Danube river erosion exposed big outrocps of Middle and Upper Pleistocene sediments (loess palaeosol sequences-LPS) at surface (Fig. 2).

The oldest exposed rocks at Bansko Brdo hill belong to the Miocene volcano-sedimentary complex, and include basalt-andesite and pyroclastic rocks comprising volcanic and tuffaceous breccias and conglomerates (Fig. 2). K-Ar radiometric, whole-rock measurements indicate an early Middle Miocene age (13.8±0, 4 and 14.5±0, 4 Ma, Pamić & Pécskay, 1996). The basalt-andesite intercalates Middle Miocene (Badenian) marine calcareous sand and marl, indicating the synsedimentary character of the volcanic activity (Pamić & Pikija, 1987; Lugović et al., 1990). The oldest loess in Bansko brdo hill is detected at the Zmajevac locality and infrared optically stimulated luminescence (IRSL) method produced age of 217±22 ka, while the youngest loess has an IRSL age of 16.7±1.8 ka (Galović et al., 2009).

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Fig. 2. Geological map of Baranja region (CGS, 2009) with two loess profiles at Bansko brdo hill, encircled with red colour.

3. Material and methods

3.1. Field methods

Field investigation and sampling where carried out during winter months, because lush vegetation in spring and summer, disables finding and aproach to loess profiless. Aim was to include maximum thicknes of sediments. Bulk samples (8-10 kg) were collected from Zmajevac (Zma), Kotlina (Kot), Podolje (Pod) and Branjina (Br) loess outcrops for sedimentological analysis. These four outcrops make two loess profiles: northern and southern, regarding their position on the slopes of Bansko brdo hill. Field investigation included taking samples, measuring thickness of sediment, defining litology, GPS positioning and photographing. Diferent horizons in loess where recognized and described. Depending on that in-situ horizon diversity, sampling was carried out. From typical loess, sampling frequency was 1.5 m on southern slopes of Bansko brdo hill. On northern slopes sampling frequency in loess was arround 0.5 m. Total of 30 loess samples where taken.

3.2. Lab methods

Grain-size analyses combined wet sieving and the pipette method. Classification of the grain size distribution follows Wentworth (1922). Mineral abundances (modal analyses) used the 0.063-0.125 mm calcite-free fraction. Heavy and light mineral fraction (HMF and LMF) were separated in bromoform liquid (CHBr3, δ=2.86 gcm-3) by gravity. Qualitative and quantitative analyses of the fractions were based on 300-350 grains per sample and were

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conducted using a polarizing light microscope (Menge & Maurer, 1992). The carbonate (CaCO3) content was calculated from the weight difference before and after cold hydrochloric acid (5%) treatment.

Photographs of quartz grains were made using a scanning electron microscope (SEM) in the Laboratory of Geochemistry, INA oil Co. Out of 30 loess samples two with previously extracted light mineral fraction were chosen for scanning electron microscopy. One sample from the southern loess profiles (Zma 1/2) and the other from the northern loess profile (Br 1/12). More than 40 different grains were photographed, and best photographs that show complete quartz grains were selected. Photographs were taken on quartz grains in order to see the shape of grains and detailed morphology of grain surface. Microscopy was made within magnification range of X350 - X3500. Selected samples were glued to a carrier double-sided tape, and then steamed with gold which thickness is 25 nm. Thus prepared samples were placed in a container and analyzed using a scanning electron microscope JEOL, model JSM-6510 LV. Microphotographs were recorded.The microscope scans the surface of the sample by very precisely focused beam of electrons. Source of electrons is a tungsten filament that generates the high voltage electrons. The beam of electrones excites electrons within the atoms of the sample. Voltage is 15 kV during process of scanning. Energy of electrons from the beam is in direct proportion to interactively excited electrons from the sample. Energy of electrons derived from samples is collected and measured with special detectors and with the help of a microprocessor creates a pseudo image with wavelength of electrons unique to an element that is found in the sample. Detection of secondary electrons enabled images with topographic contrast. In this study, the quartz grainsurface microtexture classification method and implemented terminology are based on studies of Mahaney (1995b) and Strand et al. (2003).

4. Results

Four loess outcrops were investigated. Two are located on southern slopes of Bansko brdo hill, a and other two are on northern, more steep slopes of Bansko brdo hill. The southern loess profile makes up total of 18 m of loess (Fig. 3), while northern loess profile makes up total of 8.5 m of loess (Fig. 3). Southern loess profile has four palaeosols intercalated within five loess horizons and is defined as typical loess. Northern loess profile has two palaeosols intercalated within three loess horizins and is defined as 'slope loess' or 'loess derivated coluvium', a terms previously decribed by several authors (Bognar, 1979; Pye 1995).

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Fig. 3. Southern and northern loess profiles from Bansko brdo hill.

Detailed lithology of each loess horizon of southern profile as well with chronological frame from MIS 6 – MIS 2, has been previously described (Banak et al., 2012; Galović et al., 2009). Grain-size analysis indicate silt as the dominant grain-size fraction in all 13 studied loess samples from southern profile (Fig 4). Average share of silt-size particles is 88.11%. Coarse-grained silt is dominant silt fraction with average percentage of 41.38%. The laminated unit is composed of 81% sand, 11% silt and 8% clay, with a median grain-size of 0.22 mm. Skewness is fairly constant in all 13 samples, averaging of 0.79. Sorting is dominantly poor, with an average value 1.64. The average CaCO3 content in loess samples from the southern loess profile is 9.32%, with a maximum value of 23.3% that was recorded in the sample Kot 1/4, and the minimum value of 2.9% in a sample Zma 1/1.

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Fig. 4. Grain size distribution and coefficients of southern loess profile from Bansko brdo hill.

Grain-size analysis indicates silt as the dominant grain-size fraction in all 17 studied loess samples from northern profile (Fig. 5). Average share of silt-size particles is 90.44%. Coarse-grained silt is dominant silt fraction with average percentage of 42%. Skewnes is constant with one significant peak towards 0.5 and average value is 0.81. Sorting is dominantly poor, with an average value of 1.49 which are slightly positive compared to southern profile. The average CaCO3 content in loess samples from the northern profile is 9.92%, with a maximum value of 15.8% recorded in the samples Pod 1/1 and Br 1/12 and the minimum value of 5% recorded in the sample Br 1/11.

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Fig. 5. Grain size distribution and coefficients of northern loess profile from Bansko brdo hill.

Modal analysis of the light (LMF) and heavy mineral fraction (HMF) was made on all samples of loess and shows the following results (Table 1 and 2). In the southern loess profile light mineral fraction is dominated by quartz with an average share of 58.38%, while in the northern loess profile average percentage of quartz is 60.29%. Heavy mineral fraction is dominated by amphibole, garnet and epidote while chlorite is present in small percentages. Each of the three major groups (highlited with colour in Table 1 and 2) of transparent heavy minerals in the southern and northern loess profile is represented approximately in the range of 25 to 30%, and the relations between them vary.

It is worth noticing that incerased percentage of garnet in some samples is related with decreasd percentage of amphibole and vice versa. This ratio is recorded in samples from both southern (Kot 1/2, Kot 1/9, Zma 1/4) and northern (Br 1/6, Br 1/8, Br 1/12) loess profiles (Table 1 and 2, numbers in red colour). In all other samples percentage ratio between this two groups has more narow range.

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Table 1 Mineral assemblages from southern loess profile. Note: op=opaque minerals, do=dolomite, bi=biotite, ch=chlorite, thm=transparent heavy minerals, tu=tourmaline, zr=zirqonium, ru=rutile, am=amphibole, py=pyroksene, ep=epidote, ga=garnet, cy=cyanite, st=staurolite, tit=titanite, czt=clinocoisite, cto=chloritoide, csp=cromespinel, si=silimanite, x=undetermined, q=quartz, f=feldspar, rf=rock fragments, mu=muscovite

Table 2 Mineral assemblages from northern loess profile. Note: op=opaque minerals, do=dolomite, bi=biotite, ch=chlorite, thm=transparent heavy minerals, tu=tourmaline, zr=zirqonium, ru=rutile, am=amphibole, py=pyroksene, ep=epidote, ga=garnet, cy=cyanite, st=staurolite, tit=titanite, czt=clinocoisite, cto=chloritoide, csp=cromespinel, si=silimanite, x=undetermined, q=quartz, f=feldspar, rf=rock fragments, mu=muscovite

4.2. Scanning electron microscope (SEM) images

Electron scanning microscope analyzed two samples from Bansko brdo hill loess. All scanned and photographed grains in both samples are sand-sized particles (> 63 um). In both samples angular grains dominate. Their share is over 80% of the total number of grains in the samples. Smaller percentage of grains are very angular and partly rounded. Rounded and well-rounded grains are not detected. Over 70% of the grains in both samples are of low sphericity. On most grains schist-like fractures and ''V'' impresses are visible. Schist-like fractures were detected in over 40% of the grains in the samples. The smaller number of grains have schist-like fractures that are nearly the lenght of longer axis of grain, while the

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majority of grains have schist-like fractures with size 1/3 or 1/4 of a grain. ''V'' impresses on the surfaces are visible in 15% of total number of grains. The size of these textures is in range from 3 μm to 8 μm. They are usually clustered on smooth, flat surfaces of grains, and in smaller number of grains are present in form of individual'' V'' impress. Small percentage of grains displayed sets of parallel striations. Percentage of grains with striations marks is about 5% of total number of grains. Length of striation marks on average is between 15-20 μm and sets are consisting of ten straitions in average.

Sample Zma 1/1:

Fig. 6. SEM images of quartz grains from southern loess profile. Note: A: Detail of'' V'' impress (1) and lot of small dents and cracks in the surface of grain. B: Whole grain, schist-like fracture (2) and'' V'' impress (1) in the upper right part of the grain. C: The same grain (0104 pic.), with focus on the'' V'' impress (1). D: Whole grain, schist-like fractures (2). E: Almost completely rounded grains with a schist-like fractures (2). E: Almost completely rounded grains with a schist-like fractures (2). F: Grain surface displays the'' V'' impress (1). Parallel striations (3) are also visible.

Sample Br 1/12:

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Fig. 7. SEM images of quartz grains from northern loess profile. Note: G: Subangular grain with partially visible schist-like fracture (2). H: Whole, semispherical grains with a schist-like fracture (2) and severe'' V'' impress (1). I: The same grain (0112 pic.), zoomed in on'' V'' impress (1). J: The lower part of the grain, partially rounded, with ''V'' impress (1). K: Subangular grain with a big schist-like fracture (2). L: Subangular grain with lots of striation marks and schist-like fracture (2).

5. Discusion

Almost 50% of loess profiles investigated by Nemecz et al. (2000) are constituated of coarse silt (20-45 μm) grain size. Loess profiles from Bansko brdo hill in most sedimentological characteristics can be corelated with other loess profiles in Pannonian Basin. Grain size distribution displays a dominant share of coarse silt, as in other loess profiles from the eastern Croatia, like Šarengrad (Galović et al., 2011) and Vukovar (Wacha & Frechen, 2011) which are located in range of 50 km from Bansko brdo hill. The percentage of sand is in a similar range as in other loess profiles in Pannonian Basin and varies from 5% to 20%. Northern loess profile from Bansko brdo hill has slightly higher percentage of sand-size particles, especially in the base of LPS.When reconstructing the loess deposition in a specific locality geologist must take into account various factors and concepts. Pye (1995) described the necessary conditions and processes that lead to formation of loess deposits. According to him there are two basic requirements for the formation of thick loess deposits: 1.) Source area sufficiently rich with silty material 2.) Presence of a adequate 'entanglement' in areas in which silt is accumulating. If both conditions are met, accumulation of loess is possible and it takes place in four phases (Pye, 1995). The source area for the primary material are mountain chains, which in this case of loess from Bansko brdo hill could be the Alps, the Carpathians and nearby Slavonian Mts. surrounding Pannonian Basin (Banak et al., 2012). Kuenen (1960, 1969), Wright (2000, 2007) and Smalley et al. (2005) described physical and chemical processes of weathering of rocks, resulting in production of material for the later formation of loess. Weathering of parent rocks is a combination of several processes. Glacial erosion, fluvial erosion, freez-thaw of water/ice

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in rock crevasses, aeolian abrasion of rocks by sand particles and tectonic movements are the most important processes of weathering. This is the first phase in the creation of loess deposits. Subsequently, streams, floods and rivers transport the material in flood plains, which constitutes the second phase. In the third phase in the summer period, dried river sediment which is dominated by silt-sized particles together with small amounts of fine-grained sand, is exposed at surface and can be subjected to deflation. In the fourth phase northern winds (Hobbs, 1942, 1943) blow away the sediment and transport it in large accomodation areas, like the steppes of Pannonian Basin. It should be noted that deflation of silt-size and sand-size particles was possible only if vegetation, which acts as a stabilizing factor of sediment, did not grow. At the same time, the presence of vegetation and microorganisms within, wich excrete polysaccharides and create so-called Biological Loess Crust (BLC), is an essential factor in the stabilization and erosion prevention of wind deposited particles (Smalley et al., 2011). It is unlikely that the deflation was effective in the winter, because snow or/and ice covered the sediment. It is known that in Europe thickest loess deposits are regularly very close to major rivers such as the Danube, Rhine, Tisza, Dniepar and Dniestar (Smalley et al., 2009). It shows how much the alluvial, flood plain sediment sediments is important in the formation of loess deposits. Thickness of loess in the vicinity of large rivers (in average 50 km from river beds) suggests that most of the silt and sand particles, before final sedimentation, were transported at relatively short distances thus, aeolian transport has proximal character. The predominant mode of aeolian transport is saltation and only the smallest particles, such as fine-grained silt, are transported in air suspension (Goossens, 1988; Smalley et al., 2009). There is also a division of the processes that result in the formation of loess in three phases. So Smalley et al. (2009) propose the following three stages: 1.) weathering 2.) fluvial transport/deposition of silt and sand 3.) aeolian deflation of sediment from floodplains. They believe that the process can be distinguished in four phases, as indicated in the previous concept (Pye, 1995). In doing so, the second phase should be divided in two separate processes: transport and sedimentation (Smalley et al., 2009). Both processes are important because they enhance the sorting of particles, particularly because they removes the smallest particles of fine-grained silt and clay and thus form a non-cohesive sediments with high ratio of silt/clay. That non-cohesive sediment can be easely subjected to deflation.This research proposes the introduction of five phases in the process (Fig 8), describing the formation of loess-palaeosol sequences (LPS) in Baranja. The same principle could be applied to describe formation of thick LPS in the entire Pannonian Basin.

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Fig. 8. Schemtic presentation of processes divided in five phases required for loess forming.

Complex process of transporting silt and sand particles can be best explained with SEM images which display shape of quartz grains and surface textures (Trewin, 1988). The study of surfaces under high magnification provides insight into the mechanical fractures of quartz grains. These fractures are 'fingerprints' of different types of transportation. For this purpose, numerous photographs of variety of quartz grains from diferent sediments were scanned and atlases of surface textures, shapes, and fractures were made (Mahaney, 2002). If a quartz grains originate from crystalline rocks they have an extremely low sphericity and are full of cracks (Trewin, 1988). Precisely this grain shape and forms are observed on quartz grains from the loess profiles of Bansko brdo hill. Schist-like fractures (a), that are visible in most grains in both samples, are effect of glacial and aeolian transport of silt and sand (Strand & Immonen, 2010). A large number of grains on the surface have so called '' V'' imppresses (b) that occur as a result of the grinding, bouncing and collision between grains in the process of saltation. They can also be the effect of simmilar process but in the rivers and streams with high water energy (Mahaney, 2002; Strand & Immonen, 2010). A small number of grains have visible sets of parallel striations (c) which indicates the process of glacial abrasion of grains under the pressure of ice (Strand & Immonen, 2010). These three most common textures (a,b and c) on quartz grains in samples from Bansko brdo hill loess confirm the complex process of transporting silt and sand from the place of their origin, to sedimentation area. Experimental work in the laboratory wind tunnels measured wind energy, and the speed at which certain mechanical grain damage can be produced (Bauer et al., 2004). It turned out that the aeolian transport over short distances in short time interval is sufficient to cause significant mechanical damage to the quartz grains (Costa et al., 2012). It was found that saltation of sand-size particles starts at wind speed of 8 m/s and when the wind speed is increased up to 13 m/s sand-size particles were lifted and transported in air suspension (Costa et al., 2012). The experiment was conducted in environment with a relatively high percentage of moisture in the air (about 80%), so we can assume that in more arid conditions saltation and airlift in suspension occur at lower wind speed. There is no data for silt-sized particles, but since they are smaller and lighter then sand-size particles, the minimum wind speed required to start the saltation is much lower than 8 m/s. By comparing the shapes and textures recorded in quartz grains of Bansko brdo loess with experimental data, it can be assumed that

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the quartz grains are of glacial origin and were transported in Baranja in several phases. The final phase-aeolian transport, has proximal character.

Comparing heavy mineral assemblage from LPS at Bansko brdo hill, with investigation of Thamó-Bozsó & Kovács (2007), it is obvious, that the main source area for loess in Baranja is from the Danube flood plain sediments. The main transport direction was from the North or North-West. Nevertheless, the higher concentration of amphiboles in southern and northern loess profiles (if compared with those from the Danube plain in central Hungary), suggests an additional source area. The Western Carpathians with Neogene calc-alkaline volcanic rocks is the major source for amphiboles (Thamó-Bozsó & Kovács, 2007). The percentage of amphiboles in the HMF in Baranja is fairly constant, averaging 27,2% in southern loess profile and 25.4% in northern loess profile. Alternatively those minerals could also be denudation products from locally exposed volcanic and metamorphic rocks of the southward neighboring Slavonian Mts. (Jamičić et al., 1987). Mt. Krndija and Mt. Papuk, which are the closest to Baranja of all the Slavonian Mts., consist of amphibolites. Furthermore, Pliocene sands from the northern slopes of Mt. Krndija and Mt. Papuk are of local origin and contain abundant amphiboles (Jamičić et al., 1987). It is useful to determine did the wind direction changed during Late Pleistocene. Following the work of Martinson et al. (1987) and adjustements made by Wooilard & Mook (1982) and Vandenberghe (1985) it is fair to say that MIS stages 4, 3, and 2 greatly conform with Early, Middle and Late Pleniglacial in Europe loess region.The investigation of grain-size record and mass accumulation rates of loess in central and eastern Europe suggest a domination of western winds during the Early and Middle Pleniglacial in central and eastern Europe, while the Late Pleniglacial was dominated by northwestern or northern winds (Bokhorst et al., 2011). In this investigation it is obvious that certain differences occured. Amphibole percentage in 8 upper samples from southern loess profile display considerably higher values then samples from Danube flood plain sediments. This two upper horizons of loess are deposited during MIS 4 and MIS 2 (Banak et al., 2012). For MIS 3 stage there are no data, because palaeosol was not sampled. Corealting ages of these two loess horizons with percentage of amphiboles in 8 samples it is possible to reconstruct the wind direction during MIS 4 and MIS 2 for Baranja region (Fig. 9). Diference regarding investigation of Bokhorst et al. (2011) is present in loess horizon deposited during MIS 4, while upper loess horizon deposited during MIS 2 displays same wind direction. During MIS 4 period wind direction that transported silty material to Baranja was from nort-nortwest and not from west (Fig. 9).

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Fig. 9. Wind direction in central and eastern Europe during Pleniglacial. Corelation with MIS stages and Baranja loess is set in Galović et al. (2009) and Banak et al. (2012). Difference beetwen Baranja and other loess profiles in Pannonian Basin is present during Early Pleniglacial or MIS 4 stage.

6. Conclusion

Loess is not just accumulation of airborne dust (Pecsi, 1990). This is certainly true statement supported with data from that investigation. Never the less, aeolian transport is

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critical factor in formation of thick loess deposits in Baranja, aswell in other regions of Pannonian Basin. This final phase in complex process of transporting silt and sand from source area to acommodation space can be regarded as conditio sine qua non in terms of necessity for generating thick loess-palaesol sequences. SEM images confirm complex multi-phase transport wich is divided in five phases.

Loess from Baranja is comparable with loess deposits from other Pannonian regions. Grain-size distribution displays dominance od silt-size particles. CaCO3 content is in accordance with other loess profiles. Modal analysis indicate differences which are highlited in percentage of amphibole group of minerals. Wind direction that transported silty material for Baranja LPS during Early Pleniglacial was from north and northwest as opposed to other LPS where western winds dominated.

Acknowledements

This paper was suported by Projects no. 181-181-1096-1093, 195-1951293-2703 and 195-1951293-0237 of the Croatian Ministry of Science, Education and Sports. Hereby we express our thanks to Tamara Troskot-Čorbić and Renata Slavković for providing technical support and knowledge necessary for making SEM images of quartz grains.

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