XI GeoSed Congress Italian Association for Sedimentary Geology, section of the Italian Geological Society Cagliari, September 21-27, 2015

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2 XI GeoSed Congress Italian Association for Sedimentary Geology, section of the Italian Geological Society Cagliari, September 21-27, 2015 Convenors Luca G. Costamagna, Università di Cagliari Stefano Andreucci, Università di Cagliari Scientific Committee Stefano Andreucci, Università di Cagliari Marco Brandano, SAPIENZA Università di Roma Simonetta Cirilli, Università di Perugia Luca G. Costamagna, Università di Cagliari Daniela Fontana, Università di Modena e Reggio Emilia Sergio Longhitano, Università della Basilicata Vincenzo Pascucci, Università di Sassari Luisa Sabato, Università Aldo Moro di Bari Marcello Tropeano, Università Aldo Moro di Bari Sponsored by Università di Cagliari Società Geologica Italiana, SGI IAS International Association of sedimentologists Supporter Dipartimento di Scienze Chimiche e Geologiche, Università di Cagliari

3 A revision of stratigraphic framework of the Apenninic carbonate platform successions (central-southern Italy) by comparison with other Tethyan shallow to deep marine sections. Sabrina Amodio ( a ), Vittoria Ferreri ( b ), Helmut Weissert ( c ) & Bruno D Argenio ( b ) ( a ) Dipartimento di Scienze e Tecnologie, Università degli Studi Parthenope, Centro Direzionale Isola C4, Napoli, Italy. sabrina.amodio@uniparthenope.it ( b ) IAMC, Istituto per l Ambiente Marino Costiero, CNR, Calata Porta di Massa, Napoli, Italy ( c ) Geological Institute, ETH Zürich, 8092, Zürich, Switzerland. ABSTRACT Here we revise an integrated stratigraphic study on Barremian-Aptian carbonate platform strata from successions (S. Maria, Abruzzi region and M. Faito, Campania region) located in the central-southern Apennines of Italy to better investigate the environmental and climate changes during the C-cycle perturbations, in particular before and during the OAE1a. The sedimentological, biostratigraphic and chemostratigraphic results combined with the cyclostratigraphic and sequence-stratigraphic studies provide a more detailed scenario of past environmental and climatic changes recorded in the platforms of the central-southern Tethys. The studied sections have been correlated at regional scale with the Monte Raggeto reference section where the Selli Level Equivalent (SLE) and the reversal CM0 were recognized. Major palaeoenvironmental changes occur at the Barremian-Aptian transition; in particular the Palorbitolina lenticularis and Lithocodium-Bacinella facies as well as the microbial blooms appear to reflect more mesotrophic conditions which occur at least 1.2 My before the onset of SLE. Moreover the integrated approach has produced a better age control to extend the correlation with the French Urgonian platform (Cluses section) and the Italian Umbria-Marche basin (Gorgo a Cerbara). This has allowed to calibrate the platform sequences also with the pelagic biozonations and magnetostratigraphy. Finally the eustatic nature of some palaeoenvironmental changes has been also evidenced by the sequence stratigraphic correlation with the northern margin of Tethys. correlation with the N-Tethys shallow-water record (Cluses section, France), characterized by multiple drowning episodes, will allow us to know if palaeoenvironmental changes were synchronous in both the Tethys margins and to this aim the correlation also with the pelagic record (Gorgo a Cerbara section, Italy) will permit to obtain a more precise age control of the shallow-water stratigraphy. The investigated sections S. Maria, Monte Faito and Monte Raggeto were palaeogeographically located in central Tethys and were part of isolated carbonate platforms: the Apennine and Apulia (Fig.1). By using biostratigraphy, C-isotope stratigraphy and sequence stratigraphy as a correlation tools, we consider here as reference sections: the Cluses section that belongs to the Urgonian platform, in the ESE of France (Huck et al., 2013) and the Gorgo a Cerbara section part of the Umbria Marche basin in central Italy (Sprovieri et al., 2006). KEY WORDS: Barremian-Aptian, carbonate platform crisis, C-isotope stratigraphy, OAE1a, Palorbitolina lenticularis and Lithocodium- Bacinella, Tethys INTRODUCTION During the C-cycle perturbations that culminated in the OAE1a carbonate platforms within and outside of Tethys experienced significant phases of ecological stress due to enhanced nutrient input, acidification, condensation, phosphogenesis and drowing episodes (e.g. Föllmi et al., 2006; Huck et al., 2013, Millán et al., 2009; Wissler et al., 2003). The Apennine and Apulia carbonate platforms did not drown but they continued to grow during the Barremian-Aptian times; the same environmental conditions were also documented in other southern Tethyan settings (Iberia, Croatia and Oman). Therefore we want to analyze if these platforms show evidence for biotic crisis before and during the OAE1a. The C-isotope Fig. 1 - Paleogeography of the western-central Tethys in the Early Aptian ( modified ) Abbreviations: Ap. Apennine Carbonate Platform; A. Apulia Carbonate Platform. Green star: Cluses section, Urgonian Platform, ESE France. Blue star: Gorgo a Cerbara section, Umbria-Marche Basin, central Italy 3

4 AMODIO ET AL. REGIONAL C-ISOTOPE CORRELATION Detailed lithostratigraphic and cyclostratigraphic studies were presented and discussed in Amodio et al. (2013a) paper where astronomically controlled eustatic oscillations recorded in carbonate sediments were evidenced by indentifying of the high-frequency cyclicity hierarchically organized in elementary cycles, bundles and superbundles (Amodio et al., 2008a; D Argenio et al., 2008). Moreover by a sequence-stratigraphic configuration, best recognizable in the superbundles (400 ky cycles) and lower-frequency cycles (3 rd order sequences), a high-resolution regional correlation between S. Maria and Monte Faito was carried out and compared with the reference section of Monte Raggeto (Monte Maggiore, southern Apennines, Italy), where biostratigraphic and cyclostratigraphic studies have been complemented by magneto- and isotope-stratigraphy (D Argenio et al., 2004; Wissler et al., 2004). Here we revise and implement the previous correlation adding the C-isotope stratigraphy of the S. Maria core and the M. Faito section (Fig. 2). On the whole, about 750 samples on carbonate matrix were performed for the analysis of C and O isotopes at the geochemistry laboratories of the Eni E&P Division (San Donato Milanese, Italy) and the IAMC-CNR (Naples, Italy). δ 13 C values connected by a black line usually span from about -1 to about +3 in the S. Maria section and vary from about -2 to about +3 in the Monte Faito. Overall no systematic variation of the δ 13 C values within the lithofacies associations was recognised. Moreover, low to moderate covariance of the δ 13 C versus δ 18 O values indicates the reduced influence of meteoric diagenesis on stable isotope signal even if we cannot totally exclude such a control (Amodio et al., 2008b; 2013b). For the purpose of the isotope correlation five-points moving average δ 13 C curves were calculated for both the sections and are indicated with blue and green thick lines in Figure 2. The regional correlation is supported by three independent tie-points: a) the Barremian/Aptian boundary is traced at the base of the chron M0r and within the Palorbitolina lenticularis level; b) the base of Barremian is located few meters below the base of the Monte Raggeto section taking into account the magnetostratigraphy of Iorio et al., (1996) carried out on the S1 core; the latter was correlated via C-isotope stratigraphy with the lowermost part of the outcrop (R1-R3 segment, Ferreri et al., 2004; Wissler et al., 2004) and c) the regional identification of key surfaces, such as SB and MFS in the superbundles by sequence stratigraphy. Yellow, white and orange bands represent C-isotope segments characterized by similar patterns of values. In the uppermost part we can project the SLE recognised at Monte Raggeto (R16-R18 segment in Fig. 2; Wissler et al., 2004) into the S. Maria section where an analogous positive excursion occurs from SM13 to SM15 (Fig. 2). We also note that during the SLE both superbundle thicknesses and accumulation rates in the S. Maria and the Monte Raggeto are lower than those below and above it. The SLE interval is composed of peritidal cycles thinner than those in the upper Barremian and upper Aptian intervals; this indicates slower platform growth rates during this time interval (Amodio et al., 2013a; D Argenio et al., 2011). The question marks indicate correlated intervals where the C-isotope profiles are not well comparable between the sections (Fig. 2), due to lack of some data from the S. Maria, the different resolution of the correlated values, as well as some local effects on the signal. We have reappraised the correlation of Amodio et al. (2013a) so that missing parts of the C-isotope signature emerge in the S. Maria section. In fact two gaps (grey bands) occur between SM1-SM2 and SM8-SM9 superbundles. Based on these results, it observes that the Palorbitolina lenticularis and the Lithocodium-Bacinella facies as well as the blooms of microbial carbonates (red arrows in Fig. 2) reflect palaeoenvironmental changes from oligotrophic to mesotrophic conditions at the Barremian-Aptian transition. These palaeoecological events represent the shallow-water carbonate factory response to the global biotic crisis which predating the OAE1a. Moreover the diffusion of stromatolites and loferites (brown boxes in Fig. 2) as well as of the calcrete horizons during the Barremian allows us to suppose more arid conditions compared to the humid ones that characterised the Early Aptian time. TETHYAN PLATFORM-TO-BASIN CORRELATION By extending the correlation to the N-Tethys, we consider the detailed shallow-water record of the Cluses section. Here Huck et al. (2013) individuated 13 C-isotope segments (CL1- CL13, Fig. 2). We propose that the lower yellow band could correspond to the CL4 segment while the upper white band could be correlated to the CL13 that is located immediately below the platform drowning. Moreover we can observe as changes in trophic levels (oligo-mesotrophic conditions), also documented at the Cluses section, appear partially synchronous in the correlated sections. We also propose that some regional exposures can be correlated from the North to the South of the Tethys margins. This testifies an eustatic control on the Barremian-Aptian facies evolution. Finally, we have used the C-isotope stratigraphy as a tool to extend the correlation to the pelagic record in order to obtain a more precise age control. We have chosen the Gorgo a Cerbara section that shows a very detailed integrated stratigraphy for the deep waters. Here Sprovieri et al. (2006) have provided an accurate orbital tuning on the basis of lithological cyclicity and application of spectral analysis to the δ 13 C record. Although amplitudes of pelagic C-isotope excursions are considerably smaller, δ 13 C curves appear to be comparable from shallow to deep water settings (Fig. 2). CONCLUSIONS A revised facies analysis has allowed to better characterize the shallow-water carbonate factory during the Barremian- Aptian times. The Palorbitolina lenticularis level, the Bacinella-Lithocodium consortia as well as the microbial blooms (filamentous?cyanobacteria) testify peculiar facies as 4

5 A REVISION OF STRATIGRAPHIC FRAMEWORK OF THE APENNINIC CARBONATE PLATFORM SUCCESSIONS Fig. 2 Correlation of carbon-isotope records from the Apennine and Apulia platforms (S. Maria, M. Raggeto and M. Faito) with the Cluses section from the Urgonian platform (modified after Huck et al., 2013) and the Gorgo a Cerbara section from the Umbria-Marche basin (modified after Sprovieri et al., 2006). The Cluses section appears to better preserves the C-isotope signal than that of the Apennine and Apulia platforms. Note that the Gorgo a Cerbara section is calibrated against the magnetostratigraphy and the pelagic biozonations. reflecting mesotrophic environmental conditions regionally recorded at the Barremian-Aptian transition. Evaluation of palaeoecological and palaeoenvironmental proxies allows to suppose a climatic scenario that changed from semiarid Barremian towards humid Early Aptian greenhouse conditions. In this context the C-isotope stratigraphy appears a powerful correlation tool for different lithologies and environmental settings, even if the 13 C oscillations in the carbonate platforms show a composite signal resulting from a complex combination of local, regional and global effects. Even if there are not evidences for drowning in the Apenninic platforms during the Early Aptian, as also documented in other southern Tethyan settings (Iberia, Croatia, Oman), distinct environmental changes in carbonate factory started about 1.2 My before the onset of the OAE1a. Therefore these carbonates were not totally immune to impact of OAE1a as also testified by dark-grey peritidal cycles at the SLE interval that shows slower platform growth rates. Moreover, the supraregional correlation based also on sequence stratigraphy approach shows as eustatic and climatic factors appear to control the facies evolution through time. Finally, the platform to basin correlation between the Tethys margins has allowed us to calibrate the platform sequences with the pelagic biozonations and the magnetostratigraphy. REFERENCES Amodio S., Ferreri V. & D Argenio B. (2013)a - Cyclostratigraphic and chronostratigraphic correlations in the Barremian-Aptian shallow-marine carbonates of central-southern Apennines (Italy). Cretaceous Research, 44,

6 AMODIO ET AL. Amodio S., Ferreri V.& D Argenio B. (2013)b - Lower Cretaceous Carbon-isotope records of Monte Faito and S. Maria sections. (central-southern Italy). Platform to basin correlation and orbital calibration. Journal of Mediterranean Earth Sciences, 5, 3-6. Amodio S., Ferreri V., D Argenio B., Sprovieri M. & Weissert H. (2008)a - Cyclostratigraphy and C-isotope stratigraphy of shallow-marine carbonates as proxies of climaticpaleoceanographic global changes. Case histories from Early Cretaceous of southern Italy. Rend. Online, Soc. Geol. It., 2, Amodio S., Sprovieri M., Weissert H., Ferreri V. & D Argenio B. (2008)b - Paleoceanographic signature recorded by C- isotope stratigraphy of carbonate platform strata. A methodological approach. Rend. Online, Soc. Geol. It., 2, D Argenio B., Ferreri V. & Amodio S. (2008) - Sequence stratigraphy of Cretaceous carbonate platforms: a cyclostratigraphic approach. In: Amorosi A., Haq B.U. & Sabato L. (eds.), Advance in Application of Sequence Stratigraphy in Italy. GeoActa, Spec. Publ. 1, D Argenio B., Ferreri V. & Amodio S. (2011) - Eustatic cycles and tectonics in the Cretaceous shallow Tethys. Central- Southern Apennines. Italian Journal of Geosciences, 130/1, D Argenio B., Ferreri V., Weissert H., Amodio S., Buonocunto F.P. & Wissler L. (2004) - A multidisciplinary approach to global correlation and geochronology. The Cretaceous shallow-water carbonates of southern Appenines, Italy. In: D Argenio B., Fischer A.G., Premoli Silva I., Weissert H. & Ferreri V. (eds.), Cyclostratigraphy: Approaches and case histories. SEPM Spec. Publ., 81, Ferreri V., Iorio M., Coe R., D Argenio B. (2004) - Cyclostratigraphy and Barremian time estimation at Monte Raggeto, southern Italy. 32th International Geological Congress, Florence, Italy, Abstract Book, 2, Föllmi K.B., Godet A., Bodin S. & Linder P. (2006) - Interactions between environmental change and shallow water carbonate buildup along the northern Tethyan margin and their impact on the Early Cretaceous carbon isotope record. Paleoceanography, 21, Huck S., Heimhofer U., Immenhauser A. & Weissert H. (2013) - Carbon-isotope stratigraphy od Early Cretaceous (Urgonian) shoal-water deposits: Diachronous changes in carbonate-platform production in the north-western Tethys. Sedimentary Geology, 290, Iorio M., Tarling D.H., D Argenio B. & Nardi G. (1996) - Ultra-fine magnetostratigraphy of Cretaceous shallow water carbonates, Monte Raggeto, Southern Italy. In: Morris A. & Tarling D.H. (eds.), Paleomagnetism and Tectonics of the Mediterranean Region. Geological Society of London, Spec. Publ., 105, Millán M.I., Weissert H.J., Fernández-Mendiola P.A. & García-Mondéjar J. (2009) - Impact of Early Aptian carbon cycle perturbations on evolution of a marine shelf system in the Basque-Cantabrian Basin (Aralar, N Spain). Earth and Planetary Science Letters, 287, Sprovieri M., Coccioni R., Lirer F., Pelosi N. & Lozar F. (2006) - Orbital tuning of a lower Cretaceous composite record (Maiolica Formation, central Italy). Paleoceanography, 21, PA4212, doi: /2005pa Wissler L., Funk H. & Weissert H. (2003) - Response of Early Cretaceous carbonate platforms to changes in atmospheric carbon dioxide levels. Palaeogeography. Palaeoclimatology, Palaeoecology 200, Wissler L., Weissert H., Buonocunto F.P., Ferreri V. & D Argenio B. (2004) - Calibration of the Early Cretaceous time scale: a combined chemostratigraphic and cyclostratigraphic approach to the Barremian-Aptian interval. In: D Argenio B., Fischer A.G., Premoli Silva I., Weissert H. & Ferreri V. (eds.), Cyclostratigraphy. Approaches and case histories. SEPM Spec. Publ., 81,