II Quaternario 7 (2), 1994, 677-692 WORKSHOP ON MARINE SECTIONS FROM THE GULF OF TARANTO (SOUTHERN ITALY) USABLE AS POTENTIAL STRATOTYPES FOR THE GSSP OF THE LOWER, MIDDLE AND UPPER PLEISTOCENE (Bari, Italy, Sept. 29 • Oct. 4, 1994) M. B. Cita (Workshop convener) - D. Castradori (Workshop rapporteur) Dip.to di Scienze della Terra, Universita di Milano, Milano, Italy BACKGROUND The Quaternary Working Group of the Italian Commission on Stratigraphy organized a first Workshop in November 1992 in Sicily and Calabria to investigate and discuss in the field several marine, fossiliferous, continuous, well exposed sections potentially usable as stratotypes for the Pliocene and lower Pleistocene. At the conclusion of the Workshop, the possibility of introducing a new stage for the Upper Pliocene, to fill the gap existing in between the top of the Piacentian and the N/Q Boundary as defined by its GSSP at Vrica, was discussed and considered viable. The San Nicola Section (see Channell et al., 1992) close to Gela (Sicily) visited during the Workshop, was considered to meet the international requirements. On the contrary, other exposures visited during the November 1992 Workshop and previously proposed as stratotypes for the "Selinuntian" (lower Pleistocene) by Ruggieri & Sprovieri (1979) and for the "Crotonian" (middle Pleistocene) by Ruggieri et al. (1977) were judged, by the Working Group, unsuitable as a reference for a global standard because of their near-shore setting strongly affec­ ted by eustatic/tectonic disturbances, and consequent sedimentary gaps. Highly interesting exposures of terrigenous to hemipelagic sediments deposited in the depocenter of the Apennine foredeep (NW of the Gulf of Taranto) were visited: there the marine sedimentation lasted longer than in other Sicilian and Calabrian peripheral basins, extending into the middle Pleistocene. Professor N. Ciaranfi from the University of Bari and his associates are actively working in the area, in order to provide the necessary stratigraphic multi-proxy data. After the 1992 Workshop, a) Professor G.B. Vai, from the University of Bologna, concentrated on a critical re-visitation of all the mari­ ne Pleistocene stages previously defined in Italy, some of them largely used in the international literature, others more obscure or misused; b) the Gelasian stage was proposed (Rio et al., 1994) with reference to the San Nicola Section mentioned above, and c) a GSSP was defined for the base of the Emilian stage in the Vrica Section, 75 m above the Pliocene/Pleistocene GSSP (Pasini & Colalongo, 1994 ). --------------- BARI MARE ADRIA TICO BRINDISI Mar Piccolo di Taranto ~oi MontalbanoJonlco I\ • ! MIDDLE PLEISTOCENE Gallipoli UPPER PLEISTOCENE / MARE IONIO CROTONE . - LOWER PLEISTOCENE ;:, l--1 10km THE 1994 WORKSHOP Purpose of the second Workshop was to extend the in-situ observa­ tions and discussions to the marine sections of the middle and upper Pleistocene, moving around the Gulf of Taranto (Fig. 1 ), where spectacu­ lar Strombus-bearing raised beaches occur. The Workshop consisted of three parts: 1) Visit to the upper Pleistocene sections near Gallipoli and Taranto (Mare Piccolo), under the guidance of Ors . Dai Pra and Mazzanti (September 29-30); 2) Discussion of the basic philosophy and principles of stratigraphy as applied to the Quaternary marine sequences. Boundary stratotypes versus Stage stratotypes, with reference to the newly published International Stratigraphic Guide (Salvador A., Editor, 1994) (Bari, October 1); 3) Visit to the Vrica Section under the guidance of Dr. G. Pasini and to the middle Pleistocene sections of the Apennine foredeep (Fossa Bradanica) under the guidance of Prof. N. Ciaranfi. Fig. 1 - Location map. Mappa de/le localita. 678 The Workshop was long planned by the Quaternary Working Group of the Italian Commission on Stratigraphy, but the new devel­ opments of the Quaternary Subcommission of the International Commission on Stratigraphy (ICS) and the proximity of the INQUA Congress (Berlin, 1995) suggested to make it more open and international. AIQUA, the Italian Association for the Study of the Quaternary, and the Subcommission on Neogene Stratigraphy of the ICS co­ sponsored the Workshop. 9.1 13]1 i\i·dz 1-13 B E ·········· ···· · ..... .. ........ ···· ·· ······ ·· · .... ............ . : :: : r:-,.:::::::::: iGali ,;:::::: . ... . . P.9 . ..... . 0 XJO ZOO .JOO m ······ ···· · ·· ·· 0.4!+0,04 (15) C' Mlllb -~ _ _,'.:.-;:;,_-,;,-,.c;-"""......,"-'1£(1> / MIiia __.....,=~~"! / ':~Jri.~-~i':'.:: [ID 0.15!0.03 (5) A Fig. 2 - Quaternary stratigraphy of the area around Gallipoli {after Hearty & Dai Pra, 1992). Stratigrafia def Quatemario del/'area circostante Gallipoli (da Hearty & Dai Pra, 1992). EXCURSIONS The first two days of the Workshop were dedicated to visit out­ crops of Tyrrhenian sediments in stratigraphic contact with underlying and overlying strata near Gal lipoli (Figs. 2 & 3) and in the area around the Mar Piccolo di Taranto (Figs. 4 & 5).The Tyrrhenian raised beaches are richly fossiliferous, and several radiometric age determinations based on aminoacids analyses and U/Th support their stratigraphic attribution (see Hearty and Dai Pra, 1992, and references therein) . The outcrops of the area around the Mare Piccolo appeared the most promising for the definition of a GSSP for the good condi­ tions of the exposures (eventually subject to be further improved with artificial cuts) and the thickness of the deposits. 3 2 0 4 D' a The Vrica section near Crotone, which extends from the upper Pliocene to the lower Pleistocene, and where the GSSP for the P/P boundary was formally defined (Bassett, 1985; Aguirre and Pasini, 1985), was subsequently visited. The same section has been recen­ tly used by Pasini and Colalongo (1994) to propose the GSSP of the Fig. 3 - Workshop partecipants walk on the shore of Gallipoli towards a Tyrrtienian outcrop (29/9/1994) . Partecipanti de/Workshop sulla spiaggia di Gallipoli verso un affioramen­ to def Tirreniano {29/9/1994). Emilian substage (Santernian/Emilian boundary) at level p, some 75 m above the P/P GSSP. The main biostratigraphic criteria usable to recognize the base of the Emilian are the first occurrence of Hyalinea balthica and the first occurrence of large Gephyrocapsa, with an b 134 ka C -----;.- o._ ___ _.flun d 1-1026 [§] 028 MIi 0.39 MV ,=-- MIii 679 e GJ f B' .,es,: JO ~~ ~-==---=~ 20 ,. •oo 200 0 Fig. 4 - Quaternary stratigraphy of the area around the Mar Piccolo di Taranto (after Hearty & Dai Pra, 1992). Stratigrafia dei depositi quaternari dell'area circostante if Mar Piccolo di Taranto (da Hearty & Dai Pra, 1992). interpolated age of approximately 1 .48 Ma. Figure 6 (after Pasini and Colalongo, 1994) shows the distribution of calcareous nannofossils in the Vrica section and the position of the Santemian in this section, whereas Fig. 7 shows the position of level e, which identified the P/P GSSP. If the classic Vrica section was already familiar to several Workshop participants, the Montalbano lonico section, here presented as potential reference for the middle Pleistocene, was only known to a limited number of scientists who had taken part to the 1992 Workshop. A terrific work has been accomplished in less than two years, and is concisely reported in the following pages (see also Figs. 8-11). Th e Montalbano Jonico Section in the Bradanic Foredeep (southern Italy): a potential early-middle Pleistocene Boundary Stratotype (contribution by: N. Ciaranfi, A. D' Alessandro, M. Marino & L. Sabato - Geology and Geophysics Dept., University of Bari) In the south-western part of the Bradanic Foredeep, not far from the present-day Gulf of Taranto shoreline, along the Agri river, west of Montalbano Jonico, a new detailed geological mapping (Fig. 8) has shown some continuous stratigraphic successions, previously attributed to the early Pleistocene (Verhallen, 1991 ). The reconstructed section of Montalbano Jonico (Fig . 9) that forms a monocline gently dipping towards SE, has a thickness of about 350 m. It mainly consists of well stratified silty clays, intercalated Fig. 5 - Workshop participants sample a Tyrrhenian/pre-Tyrrhenian section at Punta Penna, Mar Piccolo di Taranto (30/9/94) Partecipanti def Workshop mentre campionano una sezione def Tirreniano/pre-Tirreniano a Punta Penna, Mar Piccolo di Taranto (30/09/94). 680 Legend : ~ 1 1pedm•n . ~ ~ . .,. ' s ~ Sc•,.c e ;I i I ~ . i Abr.ind■ "'.;/"'Comfflcl'\ ~ : . . . ::! ~ ~ i 15 3 « I L L L ! ◄ ◄ . :;; ~ ~ .I V I 0 COLUMNAR ~ ~ 8 .1 g i SECTION 1, :,: i a ~ 0 " i5 r ~ ~ ~ I I I I I I w JOO 1- z l w s---- ·1 .I ,,___ 0 q ---- 0 . I 25il . I- I I p Cl) 0 ----- n- w m I ..J I a. 200 ~1~-:-:,:,:, g~ '" ,........ e w d- ~ ISO c-- ' . z b- . w a- . . 0 ,oo 0 I - . ...I . I . • • . 50 a. - - - - I I . I I I I I I . . . : I I . I ' mo I I Fig. 6 • Distribution of calcareous nannofossils in the Vrica section and definition of Santernian/Emilian boun­ dary (after Pasini & Colalongo, 1994). Distribuzione dei nannofossili cafcarei neffa sezione di Vrica e definfzione def fimite Santeriano/Emiliano (da Pasini & Colalongo, 1994). with several volcaniclastic layers (V1-V9) and marly-silty and/or sandy-silty bodies; these lithohorizons are useful to correlate successions of different localities. The nine volcaniclastic layers consist of pure ash, sand rich in volcanic minerals and pumice clasts. They belong, from a compositional and geochem­ ical point of view, to two different series (De Rosa, pers. comm.): alkaline undersaturated volcanism (V1-V4) and calcoalkaline volcanism (V5-V9). The upper part of the Montalbano section represents the local regressive emicycle of the foredeep, due to the presence of marine sands and conglomerates at the base, and of continental conglomerates at the top (Figs . 10-1 1) . Biostratigraphic analyses of nannofloral assemblages based on several sam­ ples collected from the middle part of the section (about 250 m thick), allowed us to recognize three Pleistocene biozones according to the Rio et al. (1990) scheme (Fig . 9). The lower part of the sampled section has been referred to the large Gephyrocapsa Zone; the interval between the V1 layer and a strati ­ graphic level 5 m below the V2 layer has been referred to the small Gephyrocapsa Zone: both biozones indicate the younger part of the early Pleistocene . The upper part of the sampled section is referable to the Pseudoemiliania /acunosa Zone, on the basis of the occurrence of Gephyrocapsa para/le/a ( Gephyrocapsa sp. 3, sensu Rio, 1982). The distribution of this species (first occurrence at 944 ka, last occurrence at 584 ka, Castradori, 1993) is discon­ tinuous in the Mediterranean area with a ''temporary disappearance" (recorded in the Montalbano section near the V3 layer) and a "reappearance" (in the Montalbano section 20 m above the V4 layer) (see Rio et al., 1990; Castradori, 1993). The above mentioned results suggest the presence of the early-middle Pleistocene boundary in the Montalbano section. Researches are in progress, including: sedimentology, calcareous nannofossil biostratigraphy, planktonic and benthonic foraminiferal biostratigraphy, paleoecology of macrofossil communities, petrology of volcaniclastic layers, magnetostratigraphy, radiometric dating. DISCUSSION One full day (October 1, 1994) was dedicated to discuss the principles, the sections, the chronostratigraphic subdivisions to be proposed. In order to prevent a dis- organised discussion and to pro­ vide all the background information available, a tentative program was dressed (Table 1). All the planned presentations were given with minor changes in the schedule. Table 2 provides the list of Workshop participants, with their home institutions and qualifications. The discussions were alive and sometimes heated, especially those concerning the lower and the upper Pleistocene. The points of discussion may be categorized as follows: a) The principles of stratigraphy, as applied to the definition of boundary strato­ types, with reference to the new Guide (Salvador A., Editor, 1994), and the role that priority plays versus world-wide correlability. See also contribution by J. van Couvering in the following pages, a document distributed to all Workshop participants. b) The major boundaries. On this point the consensus was full. The lower Pleistocene has to start with the GSSP defined, and formally accepted, in the Vrica section (Bassett , 1985; Aguirre & Pasini, 1985). There is no reason whatsoever to change its position, which has a correlation potential much better known now than ten years ago. The middle Pleistocene should start with a point close to the upper Jaramillo reversal, to isotopic stage 25 and to the small Gephyrocapsa/Pseudoemi/iania lacunosa nannofossil Fig. 7 • Workshop participants G.B. Vai and S.laccarino sit on the Pliocene/Pleistocene GSSP in the Vrica section (2/10/94). I parlecipanti def Workshop G.B. Vai e S. lacca· rino sul GSSP Pliocene/Pleistocene neffa sezione di Vrica (2110/94). zonal boundary. Such a point was considered to have a better correlation potential than a boundary coinciding with the Brunhes/Matuyama magnetic reversal. The proposed lower/middle Pleistocene boundary is easily recognizable in the land record on the basis of mammal faunas (see contribution by A. Azzaroli later on) . N A I ( Mass. i .a Monty "' / ,/Ji(,( / ~ ._,,,"- '- - vs v• • • V3 • • • • V2 v v v Y V1 A)--.s ,;( 5 ..,......-,- 8 -- 7 V .., .., 8 V V V C:tzJ I / , ____ .,.., '- .,,.. '-' I c. \ (. C. C. \ C. L L / L C. L - (. (. ( ,(/- '-- 150 ,,,, ....... ..-l "'"'- .,,,, -- 5 I ,.... ,,,......_ 'i /; I / I/ ....__.,,.... l '- - _) I . ' \ km 681 Fig. 8 - Sketch map of the area studied by Ciaranfi et al. (1994) near Montalbano lonico; 1: alluvial deposits; 2: continental conglomerates; 3: marine sands and conglomerates; 4: silty clays and clayey silts; 8: landslides; s: measured sections. Carta schematica del/ 'area studiata da Ciaranfi et al. (1994) in vicinanza di Montalbano lonico; 1: depositi alluvionali; 2: conglomerati continentali; 3: sab­ bie e conglomerati marini; 4: argille limose e limi argillosi; 8: frane; s: sezioni misurate. The upper Pleistocene also obtained a general consensus; it had to start with termination II, with the transition from isotopic stage 6 to stage 5 and with the base of the oldest Strombus raised beach. c) The names to be used for the stage corresponding to the lower, middle and upper Pleistocene, as defined above. The discussion of this item was really heated and difficult sometimes, maybe because some Workshop participants were person­ ally involved as proponents of new stage names, or users of chronostratigraphic units not properly defined , or not largely used elsewhere or both. Points of discussion were the role of priority in the definition of a stage, the opportunity to emend deeply rooted terms, widely used in the international literature; the importance to have a good standard reference section with a clearly defined GSSP versus the interpretation given tens of years ago by various authors to some poorly known fossil localities, at times when several Proxy data now used in the integrated stratigraphic approach were not available yet. Further details on the discussion points are found in Cita and Castradori (in press, Bollettino Societa Geologica ltaliana) to which reference is made. 682 111 l e ~ z ~ 111 "' .,, 0 C: 0 ~ ..!!! .!!! 0 C: -!!! "" E r .., .g ::, "' 00 .,, 0.. -l 111 11 .J u ~ e,J .!! i- (!) ~ l § 2 Legend Sl .; 1n "' 0 0 ... ., iii "' :!.2 iiJ 0 u. 0 .• Sl 0 > .!! 0 -.; ..., ,g 0 iii" ' .!: 0 .!: 0 5l "' 0 u. < SECTION OF MONTALBANO JONICO 20 MAIN CALCAREOUS NANNOFOSSILS ~ .,, e ... "' l ~ II) X: i I I I I I I I I I I I I I I I • I I I I I I I I I I I I I I <> [ -c: Q. II) (!) cu ~ uj "' ~ "' C: "' -~ "' C: .Q "' :@ t "' 0 <> :i = i g. <> [ l -c: g. II) (!) (!) 0 C: = = Q. "' ~ i I ... Q. C: .., ..'!! (!) .S! ::, ., ;g E' II) .!! 12:: .!! "' == e "' Q. "' "' Q. "' 0 I CD (!) I I I :i 0 § <> ..!!! -!!! C: -!!! :::: E II) .g ::, ... ~ 1°0 ° I conglomerates ~ sandsand conglomerates -~ sandy sils and/or many silta Illy clays -- voldinicla&lic laye111 Fig. 10 - Workshop participants climb the beautifully exposed Fosso ldeale section (3/10/1994). Partecipanti al Workshop si arrampicano su/ bellissimo affioramento de/la sezione di Fosso Ideate (3/1011994). Fig. 9 - Composite section of Montalbano lonico and distribution of calcareous nannofossils (after Ciaranfi eta!., 1994). Sezione composita di Montalbano lonico e distribuzio­ ne dei nannofossili calcarei (da Ciaranfi et al., 1994). I Fig. 11 - Panoramic view of the badlands west of Montalbano lonico; VS is a prominent volcaniclastic marker-bed. Panorama de/le argi/le a calanchi (badlands) ad ovest di Montalbano lonico; VS indica uno strata guida di materiale c/astico di origine vu/canica. PROPOSALS Table 1 - Program of the "Discussion day". - Programma de/ "Discussion day". Societa Geologica ltaliana Commissions ltaliana di Stratigrafia Gruppo di lavoro per ii Quaternario Ass0CIAZIONE ITALIANA PER LO STUDIO DEL OUATERNARIO Presidents M.B. Gita Segretario A. Bini INTERNATIONAL UNION OF GEOLOGICAL SCIENCES INTERNATIONAL COMMISSION ON STRATIGRAPHY SUBCOMMISSION ON NEOGENE STRATIGRAPHY WORKSHOP ON MARINE SECTIONS FROM THE GULF OF TARANTO (SOUTHERN ITALY) USABLE AS POTENTIAL STRATOTYPES FOR THE GSSP OF LOWER, MIDDLE AND UPPER PLEISTOCENE OCTOBER 1 - DISCUSSION DAY TENTATIVE AG ENDA Morning Session 9.30 -12.30 9.30 M.B. CrTA - The workshop: background and motivation 9.50 D. Rro & R. SrRovrrnr - Early Pleistocene section and possible subdivision SNS 10.1 O N. CrARANFI - The evolution of chain-foredeep-foreland system in southern Italy: geody­ namic explanation for the presence of continuous Quaternary sections and possible sub­ division: present-day knowledge and related problems 10.30 D. Rro - Stratigraphic and biostratigraphic evidences for Middle Pleistocene 10.50 R. MAZZANTI & G. DAr PRA - Late Pleistocene (Tyrrhenian) sections 11.30 J. VAN Couvrn1NG - What is the relationship between the base of Quaternary and the base of Pleistocene? General Discussion Afternoon Session 14.30 - 18.30 14.30 G.C. PASINI & J. VAN COUVERING - The GSSP of the Vrica section and its world-wide correlability 15.00 A. AZZAROLI & P. AMBROS ETTI - The point of view of continental stratigraphers 15.20 A. D'ALESSANDRO - Ecostratigraphy and its application to the Montalbano sections 15.40 N. CrARANFr - Presentation of the excursion 16.00 Coffee Break 16.20 - 17.20 General Discussion possibly followed by a round table discussion Interventions by M. BASSETT, G.B. VAi, D. Rro, J. VAN CoUVERING, I. RAFF! are foreseen 683 The proposed subdivision presented here (Fig. 12) is the main result of the Workshop(s). It has not been approved by consensus, but results from a) two polls among Workshop participants, the first questionnaire being distributed after the general discussion in Bari, the second one, with even more focussed questions, after another meeting held in Crotone on October 2, 1994 and b) a postal ballot among the members of the Quaternary Working Group of the Italian Commission on Stratigraphy (indicated as GLQ on Table 2) . The rules of IUGS have been applied (60% QuoRuM) to calculate the majority, which was large enough as to consider the proposed subdi­ vision on firm grounds. The following comments are aimed at clarifying the scheme, which extends into the Pliocene, starting from its lower, older parts. The GELASIAN stage has been recently proposed (Rio et al., 1994) for the stratigraphic interval above the Piacenzian and above the event at approximately 2.5 Ma (final event of the gradual initiation of glaciation in the northern hemisphere). This interval was not covered by a formal chronostratigraphic unit defined by a stratotype (Rio et al., 1991; Cita et al., in press). The GSSP at the base of the Gelasian has been proposed in the San Nicola section (Sicily) in a position slightly postdating the Gauss/Matuyama magnetic reversal (Rio eta/., 1994). The Pliocene/Pleistocene boundary, located in the Vrica section at the base of the marls overlying sapropelic layer "e" (see Fig. 7) is the only one represented in Fig . 12 to have been formally accepted by ICS and ratified by IUGS (Bassett, 1985; Aguirre & Pasini, 1985). The Italian Working Group is strongly supportive of its validity and worldwide correlability. It is pointed out that the scheme (Fig. 12) does not include a formal tripartition of the Pleistocene series in subseries (Lower, 684 Table 2 • Workshop participants, including affiliations and qualifications. I partecipanti al Workshop, con indicazione de/la qua/ifica e dell'organizzazione di appartenenza. Ambrosetti, P. * Dip. Scienze Terra Palreontology Professor Univ. Perugia Italian delegate at INQUA GLQ Azzaro Ii , A. Dip. Scienze Terra Palreontology Professor Univ. Firenze Italian Delegate at INQUA GLQ Bassett, M. G. Dept. of Geology Professor (Univ. of Wales, Cardiff) National Museum of Wales, ICS Vice Chairman Cardiff Chairman UK Commission on Stratigraphy Carobene, L. • Dip. Scienze Terra Geology Professor Univ. Genova GLQ Carrozzini , B. Dip. Geomineralogico Post-doc Univ. Bari Castradori D. AGIP S.p.A. Stratigrapher at AGIP (Rapporteur) Lab. Bolgiano Ciaranfi, N. * Dip. Geol. Geof. Geology Professor (Workshop organizer) Univ. Bari GLQ Gita, M. B. * Dip. Scienze Terra Geology Professor (Workshop convener) Univ. Milano SNS Chairman CIS Chairman GLQ Chairman Colalongo, M. L. Dip. Scienze Geol. Palreontology Professor Univ. Bologna GLQ Dai Pra, G. * ENEA-Amb/Saf/Ter ENEA Researcher Casaccia, Roma GLQ D'Alessandro, A. Dip. Geol. Geof. Palreoecology Professor (Workshop organizer) Univ. Bari Di Stefano, E. Dip. Geol. Geodesia Researcher Univ. Palermo ODP laccarino, S. * 1st. Geologia Micropalreontology Professor Univ. Parma SNS Voting Member, ODP Maiorano, P. Dip. Geol. Geof. Doctoral Student Univ. Bari Marino, M. Dip. Geol. Geo!. Post-doc (Workshop organizer) Univ. Bari Mazanti, R. * CNR-Centro Geologia CNR Researcher Dinamica e Strutturale dell'Appennino Pasini, G. CNR-Geol. Marina CNR Researcher Bologna GLQ Ratti , I. * Facolta di Scienze Researcher; ODP Univ. Chieti SNS Working Group on Pliocene Time Scale Rio, D: Dip. Geologia Micropalreontology professor Univ. Padova CIS; GLQ SNS Voting Member; ODP Sabato, L. Dip. Geol. Geof. Researcher (Sedimentologist) (Workshop organizer) Univ. Bari Sprovieri , R. Dip. Geol. Geodesia Micropalreontology Professor Univ. Palermo CIS; GLQ SNS Corresponding Member; ODP Vai, G. B. * Dip. Scienze Geol. Stratigraphy Professor Univ. Bologna CIS 'GLQ Van Couvering, J. Micropaleontology Press, Editor-in-chief ( "Micropaleontology") New York, USA PhD Geol. Cambridge SNS Expert Vernuccio, S. Dip. Geol. Geodesia Researcher Univ. Palermo CS: International Commission on Stratigraphy SNS: Subcommission on Neogene Stratigraphy of ICS CIS: Commissione ltaliana di Stratigrafia della Societa Geologica ltaliana GLQ: Gruppo di Lavoro sul Quaternario della CIS ODP: Ocean Drilling Program CNR: Consiglio Nazionale delle Ricerche *: AIQUA {Associazione ltaliana per lo Studio del Quaternario) Member Middle and Upper). This choice derives from the short time involved (less than two million years) , also following the advice of M. Bassett. It also derives from the intent to induce scientists to the extensive and correct use of stage names. The CALABRIAN stage covers the entire lower Pleistocene, and extends from the GSSP defined for the Pliocene/Pleistocene in the Vrica section to the GSSP to be de­ fined in the Montalbano lonico section, the best candidate avail­ able for the middle Pleistocene (see Excursion, and further on). A redefinition of the stage, whose use is deeply root­ ed in the international literature but not consistent through­ out, is required (see notes by J . van Couvering in the following pages; see also discussion in Cita & Castradori, in press, Boll. Soc. Geol . Ital.) . The possibility to further subdivide the lower Pleis­ tocene or Calabrian in three chronostratigraphic formal units, namely SANTERNIAN, EMILIAN and SICILIAN , was unan­ imously accepted. Their rank is that of substages. A GSSP for the Emilian substage has been recently proposed by Pasini and Colalongo (1994), at sapropel layer "p" of the Vrica section (see Fig. 6). The second stage of the Pleistocene, as here proposed, includes the sediments deposited in the time interval corre­ sponding to the "glacial Pleistocene", predating the large Tyrrhenian deglaciation. The name for this stage (IONIAN, from the Ionian Sea) and the basic criterion for the choice of its GSSP were widely supported (practically by consen­ sus) by the polls and by the postal ballott, with the lower boundary close to the last (youngest) warm episode (iso­ topic stage 25) predating the beginning of the "glacial" Pleistocene (isotopic stage 22). The latter alternative was considered , but discarded because a cold, regressive phase results inevitably in hiatuses on continental margins, and consequently is unfavourable for the base of a chrono­ stratigraphic unit. 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 22 2.3 2.4 2.5 2.6 -~ :51 0 ., .. .. E .. .. ::i; 1 ~1 ""'" '""" __ ;t _______ _ z < z 0 > w a: z < w z u a: 0 w I- I- , :, "' Zl :, "' (!) >- a: <( z a: w I- <( :, CJ (/) Cl) ·c: Q) Cl) HOL Cl) N f :::, Cl) L......J 1 ""'" '""" '":("' z <( z 0 w z w 0 0 I- (I) z w <( ::; ..J u 0.. z ;;; <( z a: <( ID ::; :ij <( w ..J <( z 0 <( z a: w !z <( (I) Sicily Calabria Bradanic trough Ionian sea KC01B (piston core) (13;14) ·······•······•· · ·· ··- ------- ---············· · · --·-·· ··· · ······ . . Montal­ bano I. (12) ··················· · ··-·-·- -- · -- · ······ ----- -- · -· ···· -- Slnga Vrlca composite (8;9; (5;6;7) 10;11) --··· ······ ····· · · · ····· - .... . . . .. . ... . . .. .. ... . . . . . Capo Rossello (1 ;2) ····•· ····· · ··· ··· ... ... . . ····· ·· ···· ·· ····· · · ·•·· San Nicola (3;4) 1--- f----<----+- -+ · ··· -· . . ..... ·· -·-· · · · ·· ·· · · · · ···- ••··- z w w <( z z (I) w w <( ..J (!) 0 w 0 0 (!) w ..J z 0.. f---- ··-· ...... ...... -- ·· · ··· ·· · · ···· · · ··· · ·· (.) <( ii: 1: Unnamed (Tarentlan?); 2: Tyrrhenlan Fig. 13 - Schematic stratigraphic extension of some classic Plio-Pleistocene sections from southern Italy and adjacent seas. Basic references are as follows: 1) Cita & Gartner (1973); 2) Di Stefano et al. (1993); 3) Channell et al. (1992); 4) Rio et al. (1994); 5) Zijderweld et al. (1991 ); 6) Hilgen (1987); 7) Hilgen (1991); 8) Selli et al. (1977); 9) Agui rre & Pasini (1985); 10) Pasini & Colalongo (1994); 11) See text for additional references; 12) Ciaranfi et al. (1994); 13) Castradori (1993); 14) Sanvoisin et al. (1993). Estensione stratigrafica schematica di alcune sezioni plio-pleistoceniche classiche dell 'ltalia meridionale e tratti di mare adiacenti. I principali riferimenti bibliografici sono: 1) Gita & Gartner (1973); 2) Di Stefano et al. (1993); 3) Channell et al. (1992); 4) Rio et al. (1994); 5) Zijderweld et al. (1991); 6) Hi/gen (1987); 7) Hi/gen (1991); 8) Se/Ii et al. (1977); 9) Aguirre & Pasini (1985); 10) Pasini & Colalongo (1994); 11) See text for additional references; 12) Ciaranfi et al. (1994); 13) Castradori (1993); 14) Sanvoisin et al. (1993). mation (marine) .. " and that "accor­ ding to evidence given this usage would place the boundary at the horizon of the first indication of cli­ matic deterioration in the Italian Neogene succession". From the above, we see that the criteria in order of increasing specificity are: i. Change to colder climate at the end of the Pl iocene; ii. Change in marine faunas indicating a change to colder cli­ mate; iii. Physical base of the Ca­ labrian Stage in its type area in Italy, selected because it contains evidence of the change to colder climate. The Pleistocene is a chrono­ stratigraphic unit, in the standard G lobal Chronostratigraphic Scale (9) . It is therefore not a "climatostra­ tigraphic" unit, or a biostratigraphic unit (8), or even a magnetostrati­ g raphic unit (14). Chronostrati­ graphic units are defined in boundary-stratotypes, primarily the lower boundary (12) , which in the case of the Global Chronostrati­ g raphi c Scale are denoted as GSSP (7). The GCS is hierarchal (9), so the Pleistocene series is defined by the base of its lowest constituent GCS stage (10) . POINT 1: The Calabrian is the lowest stage in the Pleistocene, per IGC 1948 subcommission recom­ mendation (11 ). POINT 2: The usage of the Calabrian as the lowest stage in the Pleistocene is universally well established in the Standard Global Chronostratigraphic Scale (3). PO INT 3: The base of the Calabrian, as presently defined at Santa Maria di Catanzaro , does not coincide with the base of the Pleistocene, as presently defined, and it does not adequately represent the Calabrian Stage as described by Gignoux (5) (1). POINT 4: The section at Vrica has been thoroughly described, analyzed and documented in a large number of studies (5, 13). POINT 5: The ratified GSSP for the beginning of the Pleistocene at Vrica adequately represents the concept of lower Calabrian in the sense of Gignoux, as well as the customary and long standing practise in Italy and the meaning of the 1948 London IGC resolu- (1) Gignoux considered that all of the sections which he described were part ol a synthetic concept of the Calabrian Stage, and he refused on principle to designate a stratotype when requested by the IGC Subcommission (Vai, pars.comm.). To use this name for an equivalent chronostratigraphic unit re­ quires that an appropriate stage stratotype is designated which exemplifies the fundamental characteristics (fauna, age, lithology) of Gignoux' synthesis, and that an appropriate boundary-stratotype is designated which exemplifies the oldest part of the synthesis. Neither of these considerations has been met adequately to this date. 687 tion, in regard to faunal and sedimentological evidence of a change to colder cl imate. It has been shown by IGCP 41, "N/Q Boundary", that this change is synchronous with evidence for the first typical Pleistocene glacial cycle regionally and worldwide as intended by the 1948 London IGC Subcommission in making its recommendation (10, 13). Conclusion The base of marker bed "e" in component section B at Vrica should be recognized henceforth as the lower boundary-stratotype of the Calabrian Stage, according to the 1948 IGC resolution which designated Calabrian as the lowest stage of the Pleistocene (1,2, 12). The strata above this level to the top of the Vrica Section as described in the referenced literature should be recognized hen­ ceforth as the boundary-stratotype section of the Calabrian Stage (13). Quotations (1 ). "There are stratigraphic situations where hard and fast rules cannot be applied and that common sense may indicate what will best promote clarity, understanding and progress." (p. 4) (2). "The revision and redefinition of a previously proposed and named unit requires a statement of intent to revise the unit, the rea­ sons for doing so, and a discussion of the history of the unit-author, original reference, previous treatment. If necessary, it should include a comprehensive description of the unit and designation of a new type section or type locality (or revision of the old one). The revision of a unit, to be valid, must be published in a recognized scientific medium." (p. 17) (3) . Re priority, in regard to new names (e.g. Santernian): (p . 23) "Priority in publication of a properly proposed, named and defined unit should be respected ... the critical factors should be the usefulness of the unit, the adequacy of its description, freedom from ambiguity, and suitability for widespread publication." (p. 23) (4). Re priority, in regard to earlier, obscure names: "Priority alone does not justify displacing a well-established name by one not well known or only occasionally used; nor should an inadequately established (earlier obscure name) be preserved merely for the sake of priority." (p. 23) (5) . "Revision or redefinition of previously established stratigraphic units. Revision or redefinition of an adequately established unit without changing its name requires as much justification and the same kind of information as for proposing a new unit. ... Redefinition may also become desirable because of.. .. errors in an earlier work .... Changes in major chronostratigraphic units of international scope should be made only after consultation with appropriate stratigraphic organizations." (p . 24) (6). "b. Parastratotype. A supplementary stratotype used by the original author. c. Lectostratotype. A stratotype for a previously described stratigraphic unit selected later in the absence of an adequately described original stratotype." (p. 28) Note (1 ). Gignoux did not designated a stratotype. Selli's was the first, thus the holostratotype, not the lectostratotype. (7). "Global boundary stratotype section and point (GSSP) is the term proposed for these standard boundary-stratotypes of units of the Global Chronostratigraphic Scale (Cowie et al 1986)."(p. 29. See references 12, 13) (8). "Biostratigraphic units (biozones) are bodies of rock strata that are defined or characterized on the basis of their contained fossils." (p.53) (9). "The named units composing each rank in this Standard Global Chronostratigraphic Scale encompass, as a whole, the entire stra­ tigraphic sequence, without gaps and without overlaps." (p. 78} (1 0). "The selection of the boundaries of the stages of the Standard Global Chronostratigraphic Scale deserves particular emphasis because such boundaries serve to define not only the stages but also chronostratigraphic units of higher rank such as series and systems of which stages are components." (p. 79) (11 ). "Series are defined by boundary stratotypes. If a series has been completely divided into stages its boundaries should be the lower boundary of its oldest stage and the upper boundary of its youngest stage, or the lower boundary of the lowermost stage in the overlying series. If stage subdivisions are not available, the series may be defined independently by its own boundary-stra­ totypes." (p. 80) (12). "The definition of chronostratigraphic units is best accomplished .... by the selection of boundary-stratotypes of their lower bound­ aries. These boundary-stratotypes are specific and representative sequences of strata in specific geographic localities that con­ tain unique and specific points that are the record of unique instants of geologic time." (p. 90) (13). "The selection of the boundary-stratotypes of chronostratigraphic units of the Global Chronostratigraphic Scale, where possible, should take account of historical priority and usage and should approximate the traditional boundaries. To insure its acceptance and use over wide areas, preferably worlwide , a boundary-stratotype should be selected to contain as many specific good marker horizons or other features favourable for long-distance time correlation (chronocorrelation) as possible. Examples are significant biohorizons characterized by distinctive marine, cosmopolitan fossils; magnetic polarity reversals; and stratigraphic intervals favourable for accurate numerical dating." (p. 91) 688 ► I ~~ w ~~ ~ w > ~ ~ ~ ~d~ ~ f ~ 00 ! o, I 0.2 ~ 031 04~ (/) w .J .J ll. m 'O 'O E SAM PAOLO 1 Lou!111111111un1 1ilh"Elo,hugro10,i• TRIVERSA m111111lf1Ynl PIEMONTE 11111 CJ c=J iMOLA lot1I R1 1■m1I f1un1 ofSantern0V1lley Positive Paleomagneti sm Reversed Paleomagnetism Marine sediments 1111111111 Inna ROMAGNA LIGURIA Vi llafranca d'A. lmola-Faenza Sarzana TOSCANA L. Valdarno [IJ ~ SAMIA BARBARA C11lelnmolltiS1blli011i L«1l111111lllm1 @ Paleomagnetism still to be measured Interval wrongly attributed to the "Galeriano" Position of the levels containing Man1mal Faunas C1p ilone Loc1t11m11ll1u11 TOSCANA WESTERN U. Valdarno UMBRIA UMBRIA Tiber Valley MARCHE Apennines rn m LU rn w er: UJ ::::; _J ~ 'z