Rivista Italiana di Paleontologia e Stratigrafia PALEOMAGNETIC AND PALYNOLOGIC INVESTIGATIONS IN THE UPPER VALDARNO BASIN (CENTRAL ITALY): CALIBRATION OF AN EARLY VILLAFRANCHIAN FAUNA ANDREA ALBIANELLI, AUGUSTO AZZAFiOLI, ADELE BERIINI, GIOVANNI FICCARELLI, GIOVANNI NAPOLEONE E. DANILO TORRE Key-uords: Magnetic stratigraphn Palynologn Middle Plioce- ne,Early Villafranchian, Upper Valdarno, Central Italy. Riassunto. La fauna a vertebrati rinvenuta nella pane inferiore dei depositi del 1o ciclo fluviolacustre del Bacino del Valdarno Supe- riore (successione di Castelnuovo dei Sabbioni) è stata attribuita all'unità faunistica Triversa del Villafranchiano inferiore. I più antichi giacimenti dell'Europa occidentale, come Layna (Spagna), suggerisco- no un'età della base del Villafranchiano non più antica di 3.6 Ma. In Italia I'u.f. Triversa è stata datata tra 3.0 e 3.3 Ma. Le indagini paleomagnetiche hanno permesso il riconoscimen- to della porzione superiore delf intervallo a polarità normale Gauss e della prima breve inversione sottostante (K.aena); in quest'ultima è contenuto il tetto delle ligniti basali e dei primi livelli argillosi sovra- stanti dove furono raccolti i resti di mammiferi attribuiti all'u.f. Tri- versa. Lassociazione a mammiferi è quindi databile tra 3.10 e 3.17 Ma. La base della successione conserva la testimonianza palinologica di una vegetazione indicativa di un clima caldo-umido a carattere sub- tropicaÌe, che evolve verso condizioni più fresche con progressiva rì- duzione degli elementi tropicali-subtropicali. Nel loro insieme le asso- cìazioni vegetazionali ricostruite possono essere correlate con quelle del Reuveriano dell'Europa centrale. In prossimità del tetto del corpo sabbioso che chiude il ciclo di Castelnuovo. in località "Rena Bian- ca", si hanno evidenze di una fase marcatamente arida seguita da con- dizioni più calde ed unide. Quest'ultimo cambiamento porrebbe cor- rispondere al passaggio Pretigliano-Tigliano oppure a una fluttuazio- ne stadiale-interstadiale del Pretigliano. Sulla base dei dati raccolti, quindi, si può indicare per l'inizio del Vìllafranchiano un'età più an- tica di 3.1 Ma. Abstract. The silty clays embedding an early Villafranchian mammal fauna of the Triversa faunal unit (f.u.) have been paleoma- gnetically and palynologically studied in a continuous sequence expo- sed in the Santa Barbara quarry. The study has allowed to date the earliest occurrence in ltaly of a faunal assemblage of this unit and to define the corresponding climatic conditions. The sampled section has provided a màgnetic polarity sequence of the late Gauss, where the fossiliferous layer fits the Kaena reversed interval. Its age of ca. 3.1 Ma, during subtropical climate conditions correlatable to the Reu- verian of Netherlands, suggests an older age for the beginning of the Villafranchian, possibly assocìated to a more dramatic scenario able to trigger the faunal turnover. Introduction. The beginning of the Villafranchian was darcd be- t.ween 3.0 ^nd 3.6 Ma on the basis of radiometric and paleomagnetic analyses carried out in sites with most significant local faunas. In Spain the Layna local fauna (Province of Soria) is characterized by a well differentiated association in which the occurrence of Leptobos sp. and Mimomrys cap- pettai, alongside Ruscinian species, lends the fauna a character transitional towards the Villafranchian (Perez and Soria, 1992). The sediments in which rhe fauna was collected show normal polarity magnefiz fion most plausibly assigned to the Gauss chron and therefore the deposit cannot be older than 3.6 Ma, according to the magnetic time scale of Baksi (1,993).In the Gaudíx-Baza basin, where a complete continental sequence from la- test Pliocene to Middle Pleistocene is presenr, the paleo- magnetic survey has also placed the beginning of Villa- franchian in the Gauss chron, after the 2Ln.2r Chron (Agusti et a1.,1995). In France, the Vialette fossil bearing level, charac- terrzed by a typical early Villafranchian association (Tri- versa f.u. : MN16a), overlies a volcanic bed and is pro- bably older than the Azanieras lava flow. According to the K/Ar dates of the volcanic rocks (Bander et al., 1978) the fauna is no older than 3.3 Ma, but older than 2.6 Ma. Still in France, the well known Les Etouaires fossil site of early Villafranchian age, was dated between 3.3 and 2.6Ma by Couthure 6. Pasrre (1983), on mine- rals collected from the fossil bearing deposit. Ly et al. (1983) proposed an age of 2.6-2.5 Ma, on exrrapolation from the Grande Nappe volcanic event, in the frame of a generai geological reconstruction of the history of the area. Savage and Curtis (197A) reported an age of 3.4-3.5 Ma from a sediment rich in volcanic elements under- Dipanimento di Scienze della Terra, Università di Firenze, Via La Pira 4,5AD1 Firenze, Italy ;AE rùE = 4ruvlAL--_ o.r*YYr^o"r^"""f T "" :/ o I PALUSTRINE' LACUSTRINE rf{" ,.,DELT o ::w - 9!-!1,9: o 6 ó :j-._qE-L!!lL FLUVIALw sw N.E' tt2 Fio I Schematic stratigraphy and environment interpretation of the Valdarno Basin fi1l. Modified after Sagri et al. (1994). lying the fossil bearing level. The age proposed by Ly et al. (1983) appears anomalous in comparison with other datings and deserves deeper inquiry. In ltaly, the Poggio Mirteto lignite-bearing clays (near Rome), with scanty fossils referred to the Triversa f.u., are heteropic of marine sediments of the Globorou- lía crassaformis zone, in which a voicanic ash level gave a reversed polarity magnetization, in all likelihood corre- sponding to the Mammoth subchron. In the type locali- ty of the Triversa f.u. (Boano & Forno, 1994), Lindsay et al. (1980) made a palaeomagnetic survey in the sec- tion of RDB brick factory (San Martino Formation). They found two reversed intervals separated by a normal polarity zone, and interpreted the reversed intervals as Kaena and Mammoth subchron, respectively. The short vertical extent of the section and the low quality of ma- gnetic response left their interpretation uncertain. The majority of datings reported above indicates a most probable age for the oldest Villafranchian faunal unit (Triversa f.u. : MN16a) of 3.0-3.3 Ma. In order to improve our understanding of the chronology and climatic evolution, a paleomagnetic and palynologic study was carried out in the sediments of the oldest fluviolacustrine cycle of the Upper Valdarno (Castelnuovo dei Sabbioni sequence). The sequence is well exposed in the Castelnuovo dei Sabbioni area, on the left bank of the Arno river (SE of Florence). The deposits consist (Sagri et al., 1994) of basal aiiuvial and fluvio-deltaic sands and gravels (Spedalino Sands and Gravels), grading upwards into well-bedded la- custrine silty clays and sands (Meleto Clay$. Lignite seams occur in the lower part of the lacustrine deposits and have been exploited industrially in the Santa Barba- ra mine. The lacustrine deposits are conformably over- lain by more coarse-grained deltaic sands and well sor- rcd, light coloured fluvial sands (San Donato Sand$ (Fig. t). The main lignite seam, and the silt beds over- lying it, yielded a scanty mammalian fauna represented Ficcarelli, G. Napoleone & D. Torre IRM acquisition curves from two extreme samples, labeled in met€rs, starting from the base of the 13 m thick lignite seam. Sample n. 2 is from the core, sample 148 from the upper outcrop: in the most anoxic deposits the low magne- tic coercivity behavior does not differ from that fixed in less reducing environment. by [Jrsws minimws, Thpirus arvernensis, Dicerorhinus sp., lcptobos sp. and Anancus araernensis. From the same de- posits, but from an unknown locality, came a molar tooth of Zygolophodon borsoni. This association is typi- cal of the Triversa f.u. (Torre et al., 1996). Magnetic investigations Sampling site. A section of the Meleto Clays, in the open Santa Barbara pit, has been chosen for the paleomagnetic analyses. Along an outcrop of gently dipping layers, the siity clays, including the lignite, were sampled up to the base of San Donato Sands for 150 meters. A reference level was fixed at a sandy layer 0.6 m thick, 17 m above the lignite seam. The sampling extended downwards for more than 14 m, as close as possible to the lignite bed, since the mine was being filled and the section is now covered almost completely. During the filling a borehole 62 meters long was drilled alongside the sampled outcrop; it passed the lignite and penetrated the under- lying sandstones; another 18 m long core penetrated the sandy ievel and reached the top of lignite. From the outcrop and the two cores, cubes of about 1.0 cc 'were prepared for the magnetic measurements. These were carried out at the ETH magnetic laboratory in Zirich. Magnetic properties. The quaiity of the magnetic character of the rock type has been enhanced by measuring the isothermal re- manent magnetization (IRM), for several samples taken at different stratigraphic levels, and the susceptibility of all samples at each srcp during the natural remanent ma- gnetization (I.IRM) thermal treatment. Sample 2 lvlmd = 0.325E-01 A/m Sample 149 Mmax = 0.573É+00 A,h 0 0.00 | 00 A/m J_O Examples of IRM patterns are shown in Fig. 2. Sample 148 comes from the cliff and sample 2 from the core, in a layer near the bottom of the lignite. In both cases the acquisition of IRM is detected in fields up ro 1 T (Tesla) and more than 90o/o of it steeply grows within 0.2 T; the saturation is practically attained ar 0.4 T. The NRM thermal demagnetízation curves show how a relatively strong remanence decays slightly up to 100oC, and more severely beyond this: at 250'C almost 90o/o of it is iost, and at 300oC actually nothing is left (Fig 3). The lower diagram of sample 43 is the common curve for samples magnerrzed with a normal polarity; ail samples collected from 25 m above the top of lignite going upward are normally magnefized. The vector di- rections belong to a single magnetic phase and point straightforward to the origin aiready at 150oC along the characteristic direction of the primary magnetization. Samples in and close to the lignite (e.g., sample 25) show a sudden increase berween 300 and 350oC, with a higher intensity ascribed to a new mineralogical phase im- piying that magnetite is produced. A possible alteration of clay minerals with temperature could produce moderate increases while the abruptly strong contribution to suscep- tibility can be ascribed to alteration of sulfides, as these features are more pronounced in the levels closer to the lignite (Albianellí, 1994; Albianelli er aJ,., 1995). In the present materials sulfides are not macrosco- pically evident and only diffraction anaiysis, made on separates above 63 microns in diameter, has shown traces of pyrrhotite and pyrite. I-ow coercivity and rapid decay of magnetízation, at increasing temperatures, are charac- teristic of such minerals. This is supported by the beha- vior in Fig. 4, that shows the demagnetízatíon path for a sample taken in the clay levels still close to the lignite and associated to the changes in susceptibility occurring at around 300-350"C. Thereafter a strong increase in su- sceptibility occurs and the directions become unstable. The low temperature trends are interpreted as repre- Calibration of an Early Villafranchian fauna í/|1mor MiMO 4 K/Ko 3 2 1 Fig. 3 - Two typical demagnetization curues (geographic coordina- tes) of opposite patterns. In sample 43 (30 m above the li- gnite) the intensity of normal polarity is progressively de- ^.,.:-^ --r .L-- J00oc ir va_L4/rrrÉ alu arLcr nishes, while in sample 25, f-^- l--.^-^ ^-:il:lrom rayers sîil1 rn Proxrmlty of the lignite and reversely magnetized, it undergoes a srrdden irrmn rfrer J0OoC as occurring in the anoxic ligni- te samples. sentative of the primary magnefíz tion, according to the results discussed by Albianelli (1,994) and Albianelli et aI. (1993;1,995), carrred by magnetite and authigenic sul- fides produced during and/or immediately after deposi- tion. The magnetic polarity stratigraphy has been inter- preted accordingly (Fig. 5). Sample 27 t1,3 wj-Z sampìe 43 Sample 27 Ko = 10.65'10E-05 Sl unils Mo= 2.26'195-95 Ort o susceptibility o Inlensity r ("c) 500 600 Fig. 4 - The demagnetization curves for a sample still in the rever- se interval shows the removal of a secondary component with normal pol.rrity. in rhe graph on rhe left. up to 200oC treatment. The primary magnetization, with stable direction, slightly decays up to 3O0oC. The successrte rn- crease depicts the growth of a new magnetic phase, as fun- herly remarked by the susceptibility jump after 350oC. 400300200100 0.000 I 0 A/h n/Fm!x lÍmox:0.469E-02 A/m N; -Z S; +Z A. Albianelli, A. Azzaroli, A Bertini, G. Ficcarelli, G. Napoleone G D. Tone Magnetic stratigraphy, The whole set of samples shows directions of the paleomagnetic vectors trending consistently from the initial steps of demagnetization. As discussed above, the measured polarities throughout the section yield a relia- ble reversal sequence. Even near the bottom, where the lignite seam has evidence for more reducing conditions, directions remain consistent (Albianelli et al., 1993). Santa Barbara - Stereooraohic distribution N Normal magnetic polarity occurs for more than 1.00 meters in the higher portion of the outcropping beds. In the lower section a reversed polarity takes place near the lignite, followed downwards by a normal one. The composite of Fig. 6 contains all the data produced by the overlapping sequences from the two boreholes and the surface section; in its lower portion the compo- site section extends down to the sandstone basement and the reversed interval is located to cover the upper half of the lignite seam and several meters above it. In the layers close to the top of lignite and just above it, fossils of the mid-Pliocene Triversa faunal unit were re- covered during 1957 -1958 quarrying. The succeeding long normal polarity, persisting through several hundred ka of sedimentation, can be in- terpreted as belonging to the upper Gauss, subchron C2An.1n; this, in addition, can be supported by the fact that it follows a short reversal (Fig. 5-6). The latter, the- refore, well defined within the two normals, is interpre- ted as C2An.1r. The presence of the fossil level assigned to the Triversa f.u. in a well defined position, within the Kaena subchron (C2An.1r), offers firm biostrati- graphic constraint and yields an age between 3.10-3.17 Ma, according to Baksi's scale (1993). Palynology Sampling and Methods. The Castelnuovo succession was investigated for palynological analyses since 1990, in a section 2 km di- stant from that for paleomagnetics. The Meleto Clays were sampled along a well exposed and continous sec- tion in the Allori pit of Santa Barbara mine. In the overlying San Donato Sands the few silty-clay levels in- tercalated within sands were sampled in the Rena Bianca qrrarry. On the whole, 380 samples were collected (Ber- tini,1994). Laboratory techniques involve both physical and chemical procedures (hydrochloric acid, hydrofluoric acid, Luber method, Sodium esametaphosphate, Zínc chloride of density 2, potassium hydroxide plus sieving, ultrasound sieving) in order to isolate palynomorphs from other organic components and minerals. A minimum of +00 identified pollen grains were counted for each sample. Taxa were organized in 11 groups on the basis of ecologic and climatic require- ments of their modern equivalents and represented in a synthetic palynologic diagram (Fig. 6). A list of groups is here reported as a caption to the figure: 1. Tropical-subtropical elements (Sapotaceae, Clethraceae-Cyrillaceae, etc.) and subtropical,/warm-tem- perate elements (Taxodtum, Nyssa, Myrica, etc.) deman- Dm Normal Reversed 29 359" 64' 1 760 -530 4.50 8.60 1 4.9 10.1 r Lower Hemisphere o Upper Hemisphere Santa Barbara - 90 lm ctg s VGP lalitude and Polarity 0 -90 lou 100 Stereographic distribution (bedding corrected) of all selec- ted samples used for build up the Vinual Geomagnetrc Pole path in the Meleto Clays. The list on the right sum- marizes the number of samples (n) defining the normal and reversed magnetozone, the mean declination (Dm) and inclination (Im), the confidence cone (cr95), and the preci- sion parameter (k). The polarity sequence is interpreted on the base of mammal remains located in the lignite seam and just above it, corresponding to the transition from the short reverse interval to the next normal (See also Fig.6). Circles denote samples from the outcrop, crosses from the co re. o CU o E (ú 'F (g .P^ Calibration of an Early Villafrancbian fauna ll) ding year-round humidify and s/arm conditions which may also be related to local edaphic or/and microclima- tic conditions. 2. Deciduous elements of warm-temperate and temperate climate: Carya, Quercus, Pterocarya, Juglans, Engelhardtia, Liquidambax, IJlmaceae, etc. 3. Cathaya and Pinus haploxylon r.ype. 4. Pinus and other Pinaceae represented !y pooriy preserved grains. 5. Mid-altitude conifers: Cedrus and Tiuga. AP+MP . fi:FFFFFFFFFFFFI-I ortro .K.(\\\ \ 200 \ 1\\.r ,-\ì:\ Q't_-FFIF=re1 ei?-:F=-:-E-Tr;T_l ?13 lt;zlFSFF+F=:+FE-fl .ti .s.: .. F:+l:L- ;-ì;---- q, r;: r'.,7:/7a \+++4 :_' lFT I tnii/;777t4F4++4É -Tf 6. High altitude elements: Picea and Abies plus Be- tula and Fagus. 7. and 8. Taxa lacking climatically significance plus indeterminate and/or indeterminable pollen grains; in group I Alnus and Salix are evident. 9. Mediterranean xerophltes: Qwercus ilex type, Olea, Phillyrea, Pistacia, eîc. 10. and ll.contain non-arboreal plants, prevalent herbs: Poaceae, Asteraceae, Ericaceae, etc., including such hydrophilous taxa as Nymphaeaceae, Potamogeto- naceae, Sparganiaceae. Steppe elements (Artemisia and Ephedra) are represented in group 11. Pollen flora. A rich flora is recorded, composed of eiements nowadays living in different regions in Europe, Asia and America. The high concentration of weli preserved palyno- morphs confirms the occurrence of anoxic conditions on the iake bottom. This also favoured the preservation of leaves, fruits and seeds, which are consisrently pre- sent all along the Santa Barbara section. In the sandy levels of the overlaying San Donato Sands, carpoflora is dominant whereas remains of leaves are sporadic and poorly preserved. Here pollen grains are recovered only in the rare silty-clayey beds. In the overall pollen spectra of Fig.6 forest ele- ments sharply dominate over the herbaceous ones, with exception of one spectrum corresponding to the first viable bed of the San Donato Sands. The five spectra from the main lignite level show a very high percentage of arboreal poilen grains; pollen of Taxodiaceae is dominant (Taxodiwm/Glyptostrobu). Alnus pollen grains are occasionally highly abundanr, possibly because of strong fluviatile influx. Myrica, llyssa, Clethraceae-Cyrill aceae, Qu erc us, C ary a, E n ge lb ar- dtia, Tilia, Magnoliaceae, Rhamnaceae, Rhoiptelea, Sapo- taceae, Syrnplocos, Araiiaceae are also present. The four spectra between the main lignite level and the minor one show an increase of the Pinaceae pollen grains percentage, especially of Pinus, probably recording a change in the depositional environment. Spectra belonging to the levels shortly above the secondary lignite seam do not differ significantiy from the underlying ones. The first of these samples brings a strong increase of Catbaya whlle Pinus pollen grains are noted; the second one shows a new increase of Taxodia- ceae and of thermophilous broadleaves pollen grains. Spectra from the five uppermost levels of the Me- leto clays show a decrease of subtropical and warm-tem- perate elements; the mesophyious element Cathaya in- creases, as well as the microthermal ones, particularly Picea. Macroflora studies reveal the orominent occurren- U) o (o U) a U) rFÉffiI ì +! r Ll,tll i a --- " -:T.tt-.) jjjj J-- F I ic 1l tl (D co \ '\. Composìte stratigraphic section of the whole Casteinuovo dei Sabbioni sequence (tickness in meters). The sampled section starts from the base of lignite. "F" indicates the fossiliferous 1evel. From left: magnetic polaritn lithostrati- graphy and syntetic pollen diagran that displays the per- centate of the pollen groups for which explanations are in tne text. tt) - ; o I o Fi. A A. Albianelli, A. AzzaroLi, A. Bertíni, G. Ficcarelli, G. Napoleone & D. Torre ce of Fagus in the same levels (Roiron P., pers. comm. Iee4). The upper San Donato Sands is dominated by pollen grains of steppe elements, mainly Artemisia and a new increase of forest elements (particularly Cathaya and Carya) is recorded on its top. Paleoenvironmental evolution. The preliminary palynologícal data evidence diffe- rent vegetational phases which took place during the de- position of the Castelnuovo succession. During the development of the peat bog, starting about 3.1 Ma, the vegetation is dominated by forest ele- ments such as Taxodiaceae, Nyssa, Myrica, Engelhardtia, while Pinaceae probably had a restricted distribution. Climatic conditions seem characterizedby low seasonali- ty and by high humidity and temperature. A humid subtropical, 'warm-temperate ciimate may be suggested, simiiar to the climate now characterizing South-eastern Asia. These conditions are tn agreement with what is known from literature about this period (Suc et al., 1995a, 7995b). Subsequently the basin underwent a ra- pid and strong subsidence, the water level rose and a deeper lacustrine environment developed. The pollen flora shows a progressive reduction of tropical-subtropi- cal elements, particularly evident in pollen spectra from the uppermost Meleto Clays. Here a decrease in tempe- raure is marked by the increase of highland elements (mainly Picea), among Pinaceae, and by the decrease of subtropical/warm-temperate elements. A forest vegeta- tion, though, seems to have been still dominant. A significant environmental change is recorded during the deposition of the upper San Donato Sands, characterízed by episodes of ephemeral stream and ter- minal fans. The first spectrum, characterízed by herbaceous vegetation of steppe type, seems to reflect highly arid conditions. The pollen assemblages from the Meleto Clays, representative of a forest vegetation, can be correlated with the Reuverian (Zagwrjn, 1.974; Suc and Zagwljn, 1983) whereas those of steppe type from the San Dona- to Sands can be correlated with the Praetiglian (Zagwrjn,1960) and the first glacial cycles following the onset of the Arctic glaciation dated at 2.6 Ma. This event witnessed the development of tundra in northern Europe (Zagwrjn, 1960) and of steppe in the north-we- stern Mediterranean area (Suc er al., 19954 1995b). In northern Italy a strong increase of highland taxa, main- Iy Picea, is found in the sections of Stirone (Bertini Ee Vannucchi, 1993) and Castell'Arquato (Lona, 1990), of the external Apennines. In these sections the absence of a dominantly herbaceous pollen flora could be related to local environmental conditions, although it could have been also produced by unfavourable sedimentary features. In the uppermost part of the San Donato sands a ne'w climatic amelioration, reflecting conditions of higher humidity and temperature (increase oÍ Catbaya and Carya), could be ascribed either to an interstadial of Praetiglian or to the Praetiglian-Tiglian transition. Conclusions The fossil mammals found in the Castelnuovo dei Sabbioni deposits identify the normal polarity of the paleomagnetic record from the Meleto Clays with the Gauss Chron C2An.1n. The continuity of the section, the high reliability of the magnetic signature and the sampling resolution place the local mammal assemblage within the Kaena subchron (C2An.1r) dated as 3.1.0-3.17 Ma. Palynological analysis points to a warm-humid cli- mate drifting progressively to cooler conditions that, near the top, produced a significant increase tn Picea, Abies and Fagus. Further upwards, at the top of the San Donato Sands, two closely spaced layers show two con- trasting features, of a strongly arid climate followed by a warmer and humid one. Pollen records for the Meleto Clays appear to have correlatives to the Reuverian of the biochronologic scale of Zagwtln (1960); those for the upper S. Donato Sands could indicate either the Praetiglian and the tran- sition from Praetiglian to Tiglian or a stadial-interstadial fluctuation within the Praetiglian. New light is shed on the beginning of the Villa- franchian mammal age. The mammal association of the first sedimentary cycle in the Upper Valdarno develo- ped in a warm-humid, subtropical climate. Since it seems unlikely that the faunal turnover giving rise to the Villafranchian fauna could occur in such a climate, the lower boundary of Villafranchian preceded the Kae- na paleomagnetic event. A possible trigger for the turn- over could be better identified in the cooling event pic- ked by ò18O anomaly ar ca," 3.3 Ma. Achnouledgemmts. This work was supported by grants from Ministry for Scientific and Technological Research (MURST) and National Research Council (CNR). The National Power Plant (ENEL) made available the cores and the facilities in the mine; in particular, Dr. G. Miotto and his staff kindly provided continuous field assistance. For the measurements at the ETH magnetic laboratory and the complete availability of its facilities, useful discussions and advises, Dr. F Heller is deeply aknowledged. For palynologn many thanks are due to Dr. J.P. Suc for constructive discussions and to Mrs. D. Duzer for technical assistance at the Laboratory of Palynology in Montpellier. Calibration of an Early Villafranchian fauna REFERENCES Lt7 Agusti J., Oms O., Garces M., Dinares J., Peres M. 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