AMQ abs Mannella et al PALCOM 141-145.pub Available online http://amq.aiqua.it ISSN (online): 2279-7335 Alpine and Mediterranean Quaternary, Vol. 31 (Quaternary: Past, Present, Future - AIQUA Conference, Florence, 13-14/06/2018), 137 - 141 FUCINO PALAEO-LAKE: TOWARDS THE PALAEOENVIRONMENTAL HISTORY OF THE LAST 430 KA Giorgio Mannella 1, Biagio Giaccio 2, Giovanni Zanchetta 1, Eleonora Regattieri 1, Niklas Leicher 3, Stephanie Scheidt 3, Thomas Grelle 4, Carlos Lehne 4, Christian Rolf 4, Thomas Wonik 4, Sebastien Nomade 5, Alison Pereira 5,6, Elizabeth Niespolo 7,8, Paul Renne 7,8, Melanie Leng 9,10, Jonathan Dean 9,10, Camille Thomas 11, Daniel Ariztegui 11, Mario Gaeta 12, Fabio Florindo 13, Gian Paolo Cavinato 2, Antonello Provenzale 14, Bernd Wagner 3 1 Dipartimento di Scienze della Terra, University of Pisa, Pisa, Italy 2 Institute of Environmental Geology and Applied Geoengeneering (IGAG - CNR), Roma, Italy 3 Institute of Geology and Mineralogy, University of Cologne, Cologne, Germany 4 Leibniz-Institute for Applied Geophysics, Rock Physics & Borehole Geophysics, Hannover, Germany 5 Laboratoire des Sciences du Climat et de l’Environnement (CEA-CNRS-UVSQ), Gif-sur-Yvette, France 6 Ecole française de Rome, Roma, Italy 7 Department of Earth and Planetary Science, University of California, Berkeley, USA 8 Berkeley Geochronology Center, Berkeley, USA 9 Centre for Environmental Geochemistry, School of Geography, University of Nottingham, Nottingham, UK 10 NERC Isotope Geosciences Facilities, British Geological Survey, Keyworth, Nottingham, UK 11 Section Département des Sciences de la Terre et de l'Environnement, Université de Genève, Genève, Switzerland 12 Dipartimento di Scienze della Terra, University of Roma “Sapienza”, Roma, Italy 13 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy 14 Institute of Geosciences and Georesources (IGG - CNR), Pisa, Italy Corresponding author: G. Mannella ABSTRACT: The sedimentary succession deposited in Fucino palaeo-lake potentially records the environmental history of the Central Mediterranean Region continuously since the early Pleistocene and up to recent historical times. Fucino palaeo-lake sediments are interbedded with numerous volcanic ash layers which allow the reconstruction a robust and independent chronological framework of past environment changes. This framework is a fundamental tool to synchronise different archives at a regional and extra-regional scale and to better understand the spatio-temporal climate variability in the Quaternary at the orbital and millennial-scales. Here we present new preliminary data for the last five glacial to interglacial cycles. KEYWORDS: Fucino palaeo-lake, drilling, core catcher, Quaternary, volcanic ash 1. INTRODUCTION In June 2015 drilling operations in Fucino Basin resulted in the recovery of a 82 m long pilot core (cores F1-F3 in Fig. 1) documenting the interval from early marine isotope stage (MIS) 6 to late Holocene. Investi- gations on cores F1-F3 (Giaccio et al., 2015a; 2017) documented the potential for this natural archive to pro- duce a regionally representative and independently dated record of climatic variability. From a chronological point of view, the site is particularly relevant because of its proximity to Quaternary peri-Tyrrhenian volcanic centres. (Fig. 2). These volcanic centres had an intense explosive activity which resulted in the deposition of a number of tephra in the basin. These tephra layers can be used today as important chronological and strati- graphic marker beds (e.g. Giaccio et al., 2012, 2015b; Regattieri et al., 2017). This is a crucial requirement for comparing intra- and inter-regional palaeoclimatic re- cords based on different dating methods. In particular, the rich tephrostratigraphic content poses the basis for a better understanding of the temporal relationship be- tween them and with respect to the main climatic forcing (e.g. orbital). Furthermore it allows to evaluate differ- ences in magnitude and expression of Quaternary pa- laeoclimatic change across regions. With the purpose to extend back in time the record, a new drilling campaign (cores F4-F5) was set in Fucino Basin in June 2017. The preliminary analyses so far performed on the lacustrine marls and the chronological assistance provided by the tephro-stratigraphic frame- work, indicate that the recovered succession continu- ously spans the last five glacial to interglacial cycles, i.e. from MIS 12/MIS 11 up to the Holocene. 2. GEOLOGICAL SETTING The Fucino Basin, located in the Central Apennine Chain, Abruzzo (Fig. 1a), is the largest intermountain basin in the Central Apennines. This basin is an active tectonic basin and its evolution was controlled by two antithetic fault systems (NE-SW and NW-SE; Galadini & Galli, 2000). The opening of the basin, possibly concur- rent with the onset of lacustrine sedimentation, com- menced in the early Pleistocene in response to an exten- sional phase along the Apennine Chain (e.g. D’Agostino et al., 2001). Unlike other basins in this region, Fucino Lake has continuously existed since the early Pleisto- cene and till 1875 AD, when the lake was artificially drained. https://doi.org/10.26382/AIQUA.2018.AIQUAconference 142 F ig .1 - R e fe re nce m a p o f th e F ucino B a sin (a ) Lo ca tion o f F u cin o B asin w ith respe ct to the m a in e ru ptive cente rs a ctive d urin g th e last 1.8 M a . (b ) S h ad ed relief o f th e F u cino P la in sh o w ing th e lo ca tio n o f th e G e oL azio (G L ), T e lespa zio (T S ), S tra da P ro vinciale 20 (S P ), F ucino 1 a n d 3 (G iaccio e t a l., 20 15 ; 20 17 ) an d 4 an d 5 (th is stu dy) bo re ho les. D a she d blu e line s a re the isochron es (in m s) o f the P lio-Q u ate rna ry in filling w ith respe ct to th e Q u a te rn a ry m aste r fa u lts (b old red line s= re sp on sib le fo r th e a sym m e trica l (h a lf-g rab en ) ba sin ge o m e try. D otted green lin es a re th e traces of th e a va ila b le se ism ic lin es. (c) S e ism ic lin e 3 (see tra ce in p a ne l b ) sho w ing th e in te rn a l a rchitectu re o f th e P lio-Q u aterna ry co n tine n ta l d ep o sits o f the F ucin o B asin a lon g a W -E orie nte d p ro file . T he pro jected lo ca tio n o f th e G L , S P , F 1 -F 3 an d F 4-F 5 bo reh o le s is a lso sh ow n . A , B , C : m a in u n co nform itie s; S e q . 2 M essin ia n fo red ee p sed im en ts; S e q. 3: P lio ce ne flu via l a nd a lluvial de po sites; S eq . 4 : Q ua te rna ry lacustrine an d flu via l de po sits. F ig u re m od ified after G iaccio e t a l. (201 5 a). Mannella G. et al. 143 3. MATERIAL AND METHODS 3.1 Drilling operations The drilling site (Fig 1 b, c) was selected by evalu- ating the sedimentation rate obtained from the com- bined interpretation of tephro-chronological information collected from pre-existing cores (see Fig. 1 caption) and the general sedimentary-tectonic architecture of the basin (Fig. 1 b, c). Compared to the previous drilling site (F1-F3), the F4-F5 site provided us the opportunity of recovering a less expanded sedimentary succession. At the selected site (42.00 °N, 13.54 °E), two parallel holes down to ca. 86 m below ground level (b.g.l.). Cores were recovered with identical 1.5 m long coring devices operating with an offset of 75 cm to ensure overlap be- tween the F4 and F5 series. Core catchers were sub- sampled directly in the field, whereas cores were care- fully packed and stored for further analyses. The F4 hole was logged immediately after drilling and down to a depth of 80 m b.g.l. The logging equipment consisted of a multi-sensor (gamma ray, resistivity and magnetic susceptibility) probe operating in accord to the internal protocols of the Leibniz Institute for Applied Geophysics (LIAG). 3.2. Preliminary core analysis Core opening and core description was carried out at the University of Cologne, Germany. Macroscopic tephra layers were directly sampled for further analyses in specialised laboratories, while for suspect cryp- totephra smearslides were taken for optical-microscope analysis. Cores underwent non-destructive analysis, (i.e. X-ray fluorescence scanning and magnetic suscep- tibility). Further analyses were conducted at the palaeo- magnetic laboratory in Grubenhagen (Einbeck, Ger- many) of the LIAG. Here the stable components of natural remanent magnetization (NRM) where charac- terised. After preliminary studies, a raw core composite was elaborated by taking into account drilling depths and clear stratigraphic markers, such as tephra layers, to match the F4 and F5 cores. This preliminary compos- ite profile served the purposes of core sub-sampling for further analyses. Subsampling was carried at a variable resolution (from 1 cm every 2nd cm to every 8th cm) and resulted in a set of more 2000 samples which are cur- rently being processed. 3.3 Geochemical analyses on core catcher material Total carbon (TC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), and stable oxygen iso- tope compositions were measured on discrete samples from the top of each core catcher. Samples were dried in an oven at 50 °C. After disaggregation and sieving, the fraction below 100 μm was powdered and homoge- nised for geochemical analyses. TN and TS were deter- mined with a vario Micro cube combustion CNS elemen- tal analyser (Elementar, Germany) after combustion at 1150 °C, whilst TC and TIC were measured with a DI- MATOC 200 (DIMATEC, Germany) at the University of Cologne, Germany. TOC was calculated by subtracting TIC from TC. 3.4. Preliminary tephra analyses Major and minor oxide element compositions were determined on micro-pumice fragments and/or glass shards, from some selected tephra from cores F4-F5. The analyses were carried out at the IGAG-CNR in Rome, Italy, using a Cameca SX50 electron microprobe equipped with a five-wavelength dispersive spectrome- ter analytical. 4. RESULTS AND DISCUSSION The analyses run in the core samples so far al- lowed us to recognise more than 130 macroscopic tephra layers. Preliminary tephrostratigraphic surveys evidenced the presence of 16 tephra in common with the F1-F3 drilling site in the first 35 m. This confirmed that the uppermost 35 m in F4-F5 replicate the F1-F3 record (i.e. the last ca. 190 ka). Preliminary analyses on some of the major tephra layers from the lower part of the recovered succession (i.e. below 35 m) allowed us to identify the correlatives of other important regional tephrostratigraphic markers. Among these, the most relevant are listed in the table below: The Vico α tephra, together with a sharp and clear change in the lithological properties of the sediment, constrains the lowermost part of our succession to the MIS 11-12 boundary. Results from biogeochemical analyses on the core catcher material show that the different proxies are in- volved in a significant variability, with major trends con- sistent between the different proxies (Fig. 2). Changes in TIC are assumed to be mainly related to authigenic (i.e. biomediated) precipitation of calcite, according to the results from F1-F4 core (Giaccio et al., 2015). This process could be favoured by enhanced lake primary productivity as well as by increased Ca input from the catchment (e.g. Gierlowsky-Kordesh, 2010; Vogel et al., 2010). As for TOC, similarly to TIC, its variation is gen- erally controlled by the rate of organic matter production in the lake and in catchment vegetation (Leng et al., 2013) and by the preservation of OM. Therefore higher values of both TIC and TOC could be linked to warmer and wetter periods (i.e. interglacials/interstadials), where ions and nutrient are flushed from the well-developed soils into the lake. The TOC/TN ratio is usually related to the source of OM (aquatic/terrestrial), with higher (lower) values indicating prevailing terrestrial (lacustrine) input (Meyers & Ishiwatari, 1995). The general variability expressed by the proxy se- ries depicts changes of the palaeoenvironmental con- text, which can be interpreted in the frame of the climate Fucino palaeo-lake: towards the last 430 ka variability of the last 5 glacial-interglacial cycles. This is demonstrated by the good correlation potential of the TIC and TOC curves from Fucino Lake with the LR04 benthic stack (Fig. 2). During the MIS 10, 8, 6 and 4-2 glacial intervals, reduced lake productivity and contrac- tion of terrestrial vegetation with respect to the lacus- trine one determined, respectively, lower TIC and TOC as well as lower TOC/TN ratio. Interestingly, despite the relatively low time resolution obtained from the core catcher material, our record shows some of the main features of the Middle-Late Pleistocene climate variabil- ity. This is characterised by relatively abrupt glacial ter- minations and the progressive enhancement of the 100- ka power (e.g. Tzedakis et al., 2017). 5. CONCLUSIONS Ongoing and future investigations, including de- tailed petrographic and geochemical analyses and ra- diometric dating of tephra layers, together with high- resolution biogeochemical, stable isotope and palaeo- magnetic analyses, will make it possible to fully explore the potential of the Fucino lacustrine succession as a long climatic archive. We are currently preparing a composite profile an- chored to the sedimentary succession by borehole log- ging data. This represents a fundamental step to estab- lish a reliable age-depth model. The rich tephrostrati- graphic documentation appears very promising thanks to several macroscopic tephra layers and numerous cryptotephra. Most of these tephra originate from the nearby peri-Tyrrhenian volcanic centres, which were characterised by a peculiar eruptive history. This makes Fucino tephra layers particularly suitable for both indi- rect (geochemical fingerprinting) and direct (40Ar/39Ar) dating. 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