• 2012-01-01T00:00:00+01:00 (literal)
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  • Aiello Gemma; Marsella Ennio; D'Argenio Bruno (2012)
    in 31 Congresso Nazionale GNGTS, Potenza, 21-23 Novembre 2012
  • Aiello Gemma; Marsella Ennio; D'Argenio Bruno (literal)
  • Poster (literal)
  • CNR-IAMC Sede di Napoli (literal)
  • THE CONTRIBUTION OF MARINE GEOLOGY TO THE KNOWLEDGE OF MARINE COASTAL AREAS OFF THE CAMPANIA REGION: THE GEOLOGICAL MAP n. 502 \"AGROPOLI\" (SOUTHERN CAMPANIA) G. Aiello (1a) E. Marsella (1b) B. D'Argenio (1, 2, b) (1) IAMC-CNR, Sede di Napoli, Napoli, Italy (2) Dipartimento di Scienze della Terra, Università degli Studi di Napoli \"Federico II\", Napoli, Italy a Director of the marine geological survey b Scientific Responsible 1. INTRODUCTION In the last ten years the Institute of Marine Coastal Environment of the National Research Council (CNR) of Naples, Italy has carried out an extended marine geological survey for the redaction of experimental geologic maps committed by the National Geological Survey of Italy (APAT, now ISPRA). Starting from the 2003 the CNR-IAMC Institute of Naples has further increased its activities through a Convention with the Regional Geological Survey of the Campania for a geological survey of the Campania Region at the scale 1:10.000 of the whole coastal belt comprised into the - 200 m isobath. In this framework, the necessary geophysical and geological data on the continental shelf and slope have been collected in the Salerno and Policastro Gulfs (geological maps n. 486 \"Foce Sele\"; ISPRA, 2009; n. 502 \"Agropoli\", n. 519 \"Capo Palinuro\", n. 520 \"Sapri\"); between them, it is worth mentioning a high resolution Multibeam bathymetry, allowing for the construction of a marine DEM (Digital Elevation Model). Moreover, Sidescan Sonar acoustic data have been acquired for a total coverage of the study area, in order to construct photomosaics of acoustic images of the sea bottom. The latter ones, merged to the bathymetry, have represented the base for the marine geologic cartography. The geological map n. 502 \"Agropoli\" (scale 1:50.000) includes the coastal sector offshore the Cilento Promontory between the Agropoli and Agnone towns (southern Campania) and the surrounding marine areas. On this geological map on a total amount of 635 km2 of surface about 74 km2 are represented by emerged areas and 562 km2 are represented by marine areas. The bathymetric belt 0/200 m extends for 507 km2 and represents the 79,8% of the total surface of the map. The integrated geologic interpretation of seismic, bathymetric and Sidescan Sonar data have been suitably calibrated by sea bottom samples. The sub-bottom geological structures, and, as a general rule, the morpho-structures and the seismic sequences, overlying the outcrops of acoustic basement mapped in the marine area of the geological map n. 502 \"Agropoli\" have been studied in detail using multichannel and single-channel seismics of different resolution and penetration, including the Subbottom Chirp. The interpretation of high resolution reflection profiles (mostly Subbottom Chirp) has been a valid support for the reconstruction of the stratigraphic and structural setting of the Quaternary continental shelf successions and the outcrops of rocky acoustic basement in correspondence to the Punta Licosa morpho-structural high. These areas result from the seaward prolongation of the stratigraphic and structural units, widely cropping out in the surrounding emerged sector of the Cilento Promontory (\"Flysch del Cilento\" Auct.). 2. GEOLOGIC SETTING The Cilento Promontory constitutes a morpho-structural high, interposed between the coastal depressions of the Salerno Gulf-Sele Plain and of the Policastro Gulf, whose reliefs are high up to 1700 m. These mounts are constituted by thick successions of turbidite carbonatic and siliciclastic sequences (\"Flysch del Cilento\" Auct.; Fig. 1), dipping landwards in the main carbonatic reliefs of the southern Apennines (\"Alburno-Cervati Unit\" Auct.). Normal faults, Quaternary in age, identify the rims of the structure of the Cilento Promontory. Apart the carbonatic structures of the Palinuro Cape and Bulgheria Mt and other few isolated outcrops, the reliefs of the Cilento Promontory are composed of terrigenous rocks, accumulated into deep basins in a time interval ranging from the Late Mesozoic and the Late Miocene. The oldest of these formations pertains to the North-Calabride Unit, composed of dark shales, marls and marly limestones, reaching a thickness of 1300 m. The North-Calabride Unit is overlain by Early Miocene sinorogenic units, showing a deformation rate minor than the overlying tectonic units. Proceeding upwards, the Cilento Flysch includes the Pollica Formation, the San Mauro Formation and the Monte Sacro Formation, with a total thickness of 1500 m (Bonardi et al., 1992). A sketch geological map of the northern Cilento region, where the main terranes cropping out in the area have been represented, is shown in Fig. 1 (Zuppetta and Mazzoli, 1997). The carbonatic sequences cropping out at the Palinuro Cape and in the carbonatic massif of the Bulgheria Mt show palaeo-sedimentary domains of slope-basin and different facies with respect to the neritic platform limestones cropping out in correspondence to the Alburno-Cervati Mt (Bonardi et al., 1992). During the Miocene the Bulgheria unit has been overlain by the North Calabride thrusts and by the overlying Cilento Unit. Nonetheless this, the terranes of the Bulgheria Mt are actually exposed in outcrop due to the successive uplift of the Bulgheria-Capo Palinuro area (Late Miocene-Early Pliocene) and to the consequent erosion of the flysch terrigenous units (Antonioli et al., 1994). The uplift of the Bulgheria Mt has allowed for the northwards folding of the carbonatic sequences and their thrusting on the Calabride units along a south-verging reverse fault, well exposed along the southern rim of the Cilento Promontory (Bonardi et al., 1992). The terrigenous deposits of the Cilento Flysch are actually the subject of stratigraphic-structural revisions and include several units involved by complex tectonic relationships. In particular, the \"Torrente La Bruca Formation\" is composed of arenaceous-clayey, calcareous and marly-calcareous terms (age Early Cretaceous-middle Eocene; thickness 1000-1300 m). On this formation are unconformably superimposed the \"Pollica sandstones\", composed of stratified sandstones, alternating with siltites and silty clays (thickness about 800 m) and the \"San Mauro Formation\", dated to the Burdigalian-Serravallian. The last formation shows notable facies variations: marly and arenaceous prevalent in the M.te Stella structure and arenaceous-conglomeratic in the M.te Sacro structure (Amore et al., 1992). These units unconformably overlie the Liguride Units (Frido Unit, Crete Nere Formation, Saraceno Formation) with an abrupt contact correspondent to a basal conglomerate including both crystalline rocks and platform carbonates. A sketch stratigraphic column of the Cilento Group is reported in Fig. 2 (Critelli, 1999). The Cilento Group unconformably overlies the Liguride Unit and is unconformably overlain by siliciclastic thrusts ranging in age from the Late Tortonian and the Early Messinian (\"Monte Sacro, Serra Manganile and Oriolo Formations\"). The denudation of the crustal terranes of the Calabrian Arc during the rapid uplift and erosion of the Middle-Late Oligocene up to 10 my B.P. has produced abundant clastic sediments, which accumulated in an oceanic basin from the late Paleogene (i.e. the Liguride Complex Auct.) and in several Neogenic foredeeps and depocenters localized at the top of the foreland basins, migrating outwards with the onset of the orogenic deformation (Critelli, 1999). In particular, the Cilento Group (\"Flysch del Cilento\" according to Ietto et al. 1965), ranging in age from the Langhian and the Tortonian (Amore et al., 1992; Russo et al., 1995; Zuppetta and Mazzoli, 1997) and average thickness among 1200 m and 2000 m, unconformably overlies the Liguride Units and is, in turn, unconformably overlain by the \"Gorgoglione Formation\" (Late Tortonian) and by the \"Monte Sacro, Serra Manganile and Oriolo Formations\". The Cilento Group consists of different turbidite depositional systems (Valente, 1993). Apart the turbidite siliciclastic strata, the Cilento Group includes many carbonatic-clastic megastrata and coarse grained volcaniclastic and turbiditic debris flows. In the western Cilento Promontory several morphological depressions filled by alluvial deposits have individuated, whose origin has to be attributed to structural elements with NNE-SSW (Alento Plain) and NW-SE (S. Maria di Castellabate and S. Marco plains) trends. The formation of these depressions has to be attributed to the Middle Pleistocene (Brancaccio et al., 1995); they include transgressive-regressive cycles referred to glacio-eustatic oscillations of the isotopic stages 9, 7 and 5 (Shackleton and Opdyke, 1973), downthrown of several tens of meters with respect to their original altitudes. The Cilento Promontory has been involved by a vertical uplift of more than 400 m during the Early-Middle Pleistocene. Absolute estimates of the rate of tectonic uplift involving the Cilento Promontory have been obtained evaluating the vertical distribution of the Pleistocene marine terraces along the Cilento coasts. In the Northern Cilento the oldest marine terraces (Middle Pleistocene) have been documented up to 350 m asl (Cinque et al., 1994). At the Bulgheria Mt (southern Cilento) the Late Pliocene-Early Pleistocene marine terraces are uplifted up to 450 m asl, while the terraces dated to the Emilian up to 350 m asl (Baggioni et al., 1981; Lippmann-Provansal, 1987; Borrelli et al., 1988). From the Tyrrhenian to recent times geomorphological hints have indicated a tectonic stability of the study area (Romano, 1992). This is evidenced also by the altimetric location of the Versilian beach deposits; these deposits have been found in the coastal fluvial depressions, incised during the previous glacial regression, for more than 2 km inshore (Cinque et al., 1994). Alternating episodes of tectonic uplift and subsidence in the Mt. Bulgheria area (southern Cilento) from the Early Pleistocene since the Middle Pleistocene have been recognized (Ascione and Romano, 1999). The end of the vertical movements during the Late Pleistocene is demonstrated by the occurrence of the Late Pleistocene palaeo-strandlines at altitudes comparable with those ones of the highstand deposits dated at 130 ky BP, documented in stable areas of the Mediterranean. The occurrence of the marine terraces has allowed to estimate the entity of the absolute vertical movements in the Bulgheria area (Ascione and Romano, 1999). The sum of these movements has allowed a tectonic uplift of about 400 m starting from the Santernian, 150 m of which during the middle Pleistocene. 3. DATA ACQUISITION AND PROCESSING The data acquisition has been realized during the cruise GMS03-01 carried out during the October 2003 by the IAMC-CNR of Naples onboard of the R/V Urania. More than the Subbottom Chirp profiles, which are the object of this study, Sidescan Sonar acoustic and magnetometric profiles have been recorded on the same navigation lines of the Subbottom Chirp. The Chirp Subbottom profiler is particularly indicated for the marine geologic cartography, where it is not requested a significant penetration of the marine subbottom. The data processing has been realized by using the Seisprho, which is a program for the interactive elaboration and interpretation of high resolution reflection profiles (Gasperini and Stanghellini, 2009). This program, developed under a Delphi/Kylix multiplatform for the environmental monitoring, processes files recorded in a SEGY format and produces, as a final result, seismic sections as bitmap images. A Subbottom seismic profile and the corresponding geologic interpretation is reported in Fig. 3. 4. SEISMIC STRATIGRAPHY AND MARINE TERRACED SURFACES The stratigraphic units individuated in the adjacent offshore through the seismo-stratigraphic analysis belong to the Late Quaternary Depositional Sequence; in this sequence, the spatial and temporal evolution and the lateral and vertical migration of marine coastal, continental shelf and slope depositional environments of the Late Pleistocene to Holocene glacio-eustatic cycle have been recognised. The stratigraphic succession records the variations of the accommodation space of the Late Quaternary deposits during the last 4th order glacio-eustatic cycle, ranging between 128 ky B.P. (Tyrrhenian stage) and the present-day (isotopic stage 5e). Several local unconformities overlie coarse- grained deposits, filling intra-basinal depressions or palaeo-channels located at the top of the acoustic basement. Ii is worth to underline the polycyclic nature of these unconformities. This suggests that the acoustic basement was involved in several phases of erosion/emersion, development of terraces and successive transgression, as a consequence of both Late Quaternary glacio-eustatic sea level fluctuations and of Pleistocene tectonic uplift. The geologic interpretation of seismic reflection profiles localised in the morpho-structural high of Punta Licosa has evidenced the occurrence of the acoustic basement (unit S), cropping out at the sea bottom nearshore and dipping seawards under the Quaternary deposits, which form the recent sedimentary cover. Remnants of terraced surfaces located at several depths evidence the complex morpho-evolution of the acoustic basement during the Late Quaternary. In particular, four main orders of terraced surfaces have been recognised. The oldest ones are located at water depths ranging between - 50 m and - 43 m and are genetically related with the terraced surfaces disposed at water depths ranging between - 46 m and - 44 m in the Capo Palinuro area. The second order of terraced surfaces has been identified at water depths ranging between - 27 m and - 17 m and is genetically related with the terraced surfaces located at water depths ranging between - 18 m and - 24 m in the Capo Palinuro area. The third order of terraced surfaces has been recognised at water depths ranging between - 10 m and - 14 m and is related with similar surfaces disposed at water depths ranging between - 12 m and - 14 m in the Palinuro Cape. Finally, the terrace rims occurring at - 8 m are coeval, if not precedent, the last interglacial and are related with the last part of the isotopic stage 3. On the basis of high resolution reflection seismics it has not been possible to recognise the Eutyrrhenian paleo-sea level mark or related deposits. 5. MARINE GEOLOGICAL UNITS Main mapped geologic units are herein described. The Cenozoic substrate is composed of Cenozoic siliciclastic rocks, genetically related to the \"Flysch del Cilento\" Auct. The unit crops out in the inner shelf, particularly offshore the Punta Licosa structural high and is often terraced at its top by polycyclic erosional surfaces and covered by wide beds of marine phanerogams. The littoral environment is characterized by the deposits of submerged beach and of toe of coastal cliffs, incised in the arenaceous-silty successions of the Pollica Formation. The deposits of submerged beach are composed of gravels, sandy gravels and coarse grained sands with rounded to sub-rounded pebbles in a scarce middle-fine sandy matrix; by coarse to middle grained sands, from rounded to sub-rounded, with pebbles and blocks; by middle to fine-grained litho-bioclastic sands. The deposits of toe of coastal cliff are composed of heterometric blocks, siliciclastic in nature, with siliciclastic clasts. The inner shelf environment is characterized by the deposits of inner shelf and by the bioclastic deposits. The deposits of inner shelf are composed of coarse grained litho-bioclastic sands; by middle to fine grained litho-bioclastic sands and by fine-grained pelitic sands. The bioclastic deposits are characterized by heterometric gravels, gravel sands and bioclastic sands in a scarce pelitic matrix. The latter ones represent the base of wide beds of marine phanerogams and overlie the top of outcrops of Cenozoic substrate. The outer shelf environment is characterized by clastic deposits and bioclastic deposits. The clastic deposits are characterized by middle-fine grained sands localized at the top of wide outcrops of Cenozoic substrate; by pelites and sandy pelites. The bioclastic deposits are composed of bioclastic calcareous sands in abundant pelitic matrix, organized as sedimentary drapes located at the top of outcrops of Cenozoic substrate or of Late Pleistocene relic deposits. The Lowstand System Tract is composed of coarse-grained organogenic sands, grading upwards into middle-grained sands and pelitic drapes. They are relic littoral deposits organized as coastal prisms overlying the shelf margin progradations, which represent portions of submerged beaches related to the last sea level lowstand related to the isotopic stage 2. The LST deposits form NW-SE trending coastal dunes, occurring in the south-western sector of the area, at water depths ranging between - 140 m and - 145 m. The Pleistocene relic marine units are represented by coarse to fine-grained marine deposits, probably composed of well sorted sands and gravels with bioclastic fragments and by middle-fine grained sands, with a pelitic coverage having a variable thickness but less than 2 m, localized in the north-western and south-western sectors of the area, representing relics of beach and continental shelf environment. These deposits, underlying the Lowstand System Tract, represent the remnants of older beach systems, related to the isotopic stages 4 and 3. REFERENCES Amore F.O., Bonardi G., Ciampo G., De Capoa P., Perrone V., Sgrosso I. (1992) Relazioni tra Flysch Interni e domini appenninici: reinterpretazione delle formazioni di Pollica, S. Mauro e Albidona e l'evoluzione infra-medio miocenica delle zone esterne sudappenniniche. Memorie della Società Geologica Italiana, 41, 285-297. Antonioli F., Donadio C., Ferranti L. (1994) Guida all'Escursione. Note scientifiche Geosub, 94, Palinuro, De Frede, Napoli. Ascione A. and Romano P. (1999) Vertical movements on the eastern margin of the Tyrrhenian extensional basin. New data from Mt. Bulgheria (Southern Apennines, Italy). Tectonophysics, 315, 337-356. Baggioni M., Suc J.P., Vernet J. L. (1981) Le Plio-Pleistocene du Camerota (Italie meridionale): Geomorphologie et paleoflores. Geobios, 14 (2), 229-237. Bonardi G., Amore F.O., Ciampo G., De Capoa P., Miconnet P., Perrone V. (1992) Il Complesso Liguride Auct.: stato delle conoscenze e problemi aperti sull'evoluzione pre-appenninica ed i suoi rapporti con L'Arco Calabro. Memorie della Società Geologica Italiana, 41, 17-35. Borrelli A., Ciampo G., De Falco M., Guida D., Guida M. (1988) La morfogenesi del Monte Bulgheria (Campania) durante il Pleistocene inferiore e medio. Memorie della Società Geologica Italiana, 41, 667-672. Brancaccio L., Cinque A., Romano P., Rosskopf C., Russo F., Santangelo N. (1995) L'evoluzione delle pianure costiere della Campania: geomorfologia e neotettonica. Estratto da: Assetto fisico e problemi ambientali delle pianure italiane. Memorie della Società Geografica Italiana, 53, 313-336. Cinque A., Romano P., Rosskopf C., Santangelo N., Santo A. (1994) Morfologie costiere e depositi quaternari tra Agropoli e Ogliastro Marina (Cilento - Italia meridionale). Il Quaternario, 1, 3-16. Critelli S. (1999) The interplay of lithospheric flexure and thrust accommodation in forming stratigraphic sequences in the southern Apennines foreland basin system, Italy. Rendiconti Fis. Accademia dei Lincei, s. 9, vol. 10, 257-326. Gasperini L. and Stanghellini G. (2009) Seisprho: an interactive computer program for processing and interpretation of high resolution reflection profiles. Computer and Geosciences. ISPRA (2009) Geological map n. 486 \"Foce del Sele\". Servizio Geologico d'Italia, Systemcart, Roma, Italy. Lippmann Provansal M. (1987) L'Apennin campanien meridionel (Italie). Etude geomorfologique. These de Doctorat d'Etat en Geographie Physique, Univ. d'Aix, Marseille, France. Romano P. (1992) La distribuzione dei depositi marini pleistocenici lungo le coste della Campania. Stato delle conoscenze e prospettive di ricerca. Studi Geologici Camerti, Volume Speciale, 1992/1, 265-269. Russo M., Zuppetta A., Guida A. (1995) Alcune precisazioni stratigrafiche sul Flysch del Cilento (Appennino meridionale). Bollettino della Società Geologica Italiana, 114, 25-31. Shackleton N. J. and Opdyke N. D. (1973) Oxygen isotope and paleomagnetic stratigraphy of equatorial pacific core V28-238: oxygen isotope temperature and ice volume on a 10 year scale. Quaternary Research, 3, 39-55. Valente A. (1993) Studi sedimentologici sulla successione miocenica di Monte Sacro (Flysch del Cilento). Tesi di Dottorato di Ricerca in Geologia del Sedimentario, Università degli Studi di Napoli \"Federico II\", Dipartimento di Scienze della Terra, 170 pp. Zuppetta A. and Mazzoli S. (1997) Deformation history of a synorogenic sedimentary wedge, northern Cilento area, southern Apennines thrust and fold belt, Italy. Geol. Soc. Am. Bulletin, 109, 698-708. (literal)
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