Synthe,Sis of Calcareous Nannofossil Events in Tethyan Lower and Middle Jurassic Successions

Rivista Italiana di Paleontologìa e Stratigrafia

SYNTHE,SIS OF CALCAREOUS NANNOFOSSIL EVENTS IN TETHYAN LOWER AND MIDDLE JURASSIC SUCCESSIONS

EMANUELA MATTIOLIl 8. ELISABETTA ERBA2

Recebed March 18, /999; accepted September 2t, 1999

Key-uords: Calcareous nannofossils, biostratigraphl', Lower posto per l'intervallo Hettangiano-Batoniano sono srxri disrinti 4/ and Middie Juriissic, Te thys, Mcdrtcrrancan Province. eventi principàI basati su t;rxa resistcnti alla diagenesi e comuni, 17 eventi basati su taxa rari raa ubiqtiitari, e 12 eventi potenziaL che Abstact. This paper is a synthesis of calcareous nannofossil richiedono ulterrori controlli:r causa di problerni tassonomici e dis- biostretigrephy' for the Lower and Middle Jurassic of the Mediter- tribuzione sporadica. Vienc inoitre proposto per l'area retide:ì LÌno ranean Province based on several sections from Northern and Central schema biostratigrafico consistentc in i1 zone e 15 sorrozone Italy. Nannofossil events rvere calibrated n'ith ammonite biostratigra- La biostratigrafia propost:r é stara confronrate con recenti sin- phy and, when necessary ammonite-controlled sections in South East tesi biostratigrafiche conpilate per Portogallo, Marocco, Svizzera e ii Fr;rnce were incorporated. Data derive from previously published bio- Regno Boreale e sono stati ìnclividuatr 2Z er.enti riproducibili nelle strxtigrxphies and unpublished data of the authors. varie regioni. Il diacronisrno di rnolti bio-orizzontr é, e nostro awrso, 'I'he large data-set allowed estirnates of reliability and repro- apparente e dovuto essenzialmcnte elle diverse zoneziom ad Anmoni- ducibilitl' of single events. As r result, in the Hetr:rngran-Bathonian ti utilizzate in varie aree. In Italia/Francia, é possibile ottenere un' alta interval x.e propose 4/ nain events based on diagenesis-resistant and risoluzione stratigrafica per l'inten'allo Pliensbachiano-Baiociano. corrrrron ttxt, 17 events based on rare but ubiquitous taxa and 12 Sinemuriano e Batoniano sono car:Lrreriz-zati dalla risoluzione piir potential events requiring further invcstigations due to rlxonomic bassa, ma sono disponibili solo poche sezioni con controllo di problen-rs and sporadic occurrence. A biostratigraphic schene, con- An'rmoniti e litologie fevorcvoli per un misliorarnento. sisting of 11 zones and 15 subzones, is proposed for rhe Terhyrn Questo srudio conferme l'enorn're potcnzialità della biostrati, Lol.er :rnd Middle Jurassic. grafia a Nannofossrli calcerei per datlre successioni del Giurlssico 'l'hc proposed biostratigraph,v is compared to recent schemes Inferiore e Medio come pure per corrclaz-ioni intr:r- e inter-regionali. compilec{ for Portueal, Morocco, Switzerland and thc Boreal Realn-r. OnIy 27 events are reproducible in various regions, but diachroneity of trrost events seerns to derive from different ammonite biostrarigra- Introduction. phies applied in different areas. A very high stratigraphic resolution is achievcd in Italy'/f11ncg for the Pliensbachian to Lower Bajocian interval. The Sinemurian and Bathonian are characterized by the lowest res- In the past decade, much atrenrion has been olution, and verv few sections with ammonire control end/or devoted to calcareous nannofossil biostratigraphy of the favourable Lithologies are available for improvernenr of nannofossil European Jurassic, for example Crux (1984; 1,987), bi os tratieraphy. Young et al. (1986), Bown (1987a and b; 1.996), Bown & This studv confirns the potential oI calcareous nannofossil Cooper (1989), Cobianchi (1990;1992), B;rldanza et al. brostratigrephy for dating Lower and Middlc Jurassic successions rs well as for intra- and inter-regional correlations. (1990) Erba (1990), Lozar (1992), Reale er a1. (1992), de Kaenel 8r Bergen (1.993), Bucefalo Palliani & Mattroli Riassunto. Presentiamo qui la sintesi della biostratigrafia a (1994), de Kaenel et al. (1996). F{owever, different bio- Nannofossili celcarei per il Giurassico lnferiore e Medio della Provin- zonations are proposed for various regions (see Bown, cia Mediterranea basata su numerose sezioni nelle Alpi Meridionali e in Italia Centrale. Gli evcnti a Nannofossili sono stati calibrari tramite la 1.996 and de Kaenel et al., 1,996 f or recent syntheses). biozonezione ad Amrnoniti e, quando necessario, sono srrti incorpo- The chronostratigraphy of the Jurassic is based on rati dati provenienti da sezioni nel Sud Est della Francia datate con anlmonite biortratigrrphl, bur iìmmon;re reco\ ery is Arlmoniti. I dati derivano da biostratigrafie precedentemente pr,rbbli- problematic in some lithotypes and in parricular areas, cete e d;r dati inediti delle scrl.enu. due to differential preservation and provincialism. This Il controllo degli eventi a Nannofossili su un largo numcro di sczioni e dr campioni hl perrnesso di stimare I'attendibilità e ripro- results in partial correlations between differenr p:ìlaeo- ducibilità dei singoli bio-orizzontr. Di conseguenza nello schema pro- geographic realms and h;lmpers the calibration of orher

(1) Dipartirnento di Scienze della Terra dell'Università di Perugia, Piazza Università, I-061OO Perugra, Iteìy.

Present address: Laboratoire de Paléontologie Stratigraphique et Paléoecologie, Université Claude Bernard - Lyon I, 27-43 1ll. du 1 Novembre, 69622Ytllevbannc Cedex, Lyon, Frunce. e-mail: mattioli@univ-lyon1.{r (2) Dipartimento di Scienze della Terra dell'UniversitàL degli Studi di Milano, via Mangiegalli 34, 2AB3 Milano, Italy e-mail: elìsabetta. erba@ unimi. it 344 E. Mattioli & E. Erba

frg. r Map of the rnain Jurassic Umbria-Marche area outcrops and location of the studied sections in the Un'rbria-Marche Basin. 0 20km r 2 SA # areas. The boundary between 1, the Boreal Realm and the Tethys Ocean approximates the .'-:lt iiL Alpine fold belt (Hallam, 1969) UMBE1TIDE i and is gradual rs suggesred by L,, Ij d'LiilL )r ammonite, brachiopod and nan- t IJ i .3 main Jurassic outcro 't.l nofossil assemblages. In f act, NOCERA ,,n]"*[ PERUGIA wirhin rhe Tethys using inverte- Studied sections ';?ssrsI brate faunas it is possible to dis- I Monte Nerone ]n \ tinguish the Submediterranean 2 Fonte Avellana Province with "European" affin- 3 - Bosso 4 - Burano i,y, and the Mediterranean 5 - Valdorbia Provi nce with "Afric:rn" rffi niry. 6 - Colle d'Orlando 'l- Most Jurassic nannofossil 7 - Fiuminata 8 - Migiana SPOLETq: biostratigraphic studies are .aì 9 - Fosso Colognola o based on Nortl-rern European 10 - Pale -.2. l5 ,rl-ó sections, mainly F,ngland, Ger- 11 - Monte Serrone l2 - Monte Civitella ,,,,,.,, I I many and Northern France ,=,il :, \ 3 - Pozzale (Boreal Realm), or on Por- 4 - Cima Panco 5 - Monte Bibico JlanNr I\,].ti SIBILLIN] tuguese areas (Submediter- ,_:- '= ir :: 6 - Somma . t.t : . : ..:= overthrusts ranean Province), whereas the 7 - Santa Restituta :'..\= Mediterranean Province has I tl - Colle Bertone ::. RiETI::l 19 - Fonte Cerro - '. a 2t been studied in less detarl. 20 - Colle Creta Recentll', Bown (1996) and de 21 - 'ferminilletto Kaenel et al. (1996) sunìn1a- rized the nannofossil biozonations avail:rble for different fossil groups. Moreover, cephalopods are rarely .rbun- areas, but with lin-rited d:rta av;.ril:rble for the Mediter- dant and continuously distribured and, therefore, ranean Province. anmonite biostratigraphic dating is often related to dis- This paper is a synthesis of the nanno{ossil events crete horizons rather than continuous intervais. recognized in ser-errl Loner and Middle Jurassrc sec- The biostratigraphic porenri:ìl of calcareous nan- tions from Northern and Central Itaiy belonging to the nofossils is quite high in the Lower and Middle Jurassic, Mediterranean Province. Most sections are ammonite- due to their rapid evolutionary rares, as well as common rich and allow a direct crlibration of n:rnnofossil bio- :lnd continuous occurrence in sediments. Although dia- horizons. Calcareous nannofossil distriburion and genesis modifies calcareous nannofioras and strong dis- events in some sections are previously published (F,rba solution and/ or overgrowth can partially or torally & Cobianchi, 1989; Cobianchi, D9a, D92;Loz.tr,7992; destroy the rnost delicate taxa (Lozar, 1,992, 1995; Mat- Reale et aI., 1992; M:rttioli, 1993, 1994, 1995; Bucefalo tioli, 1993, 1995,1997), the common occurrence of dia- Palliani & Mattioli, 199'l; Sciunnach & Erb:r, 1994; Bar- genesis-resistant forms provides ;r good stratigraphic tolini et aI., 1.995; Nini et al., 1995; Stoico & Baldanza, resolution. 1995), others derive from unpublished data of the Th'o palaeogeographic provinces were recognized authors. Nannofossil data fron-r the Belluno Basin (E,rba, in the E,uropean Jurassic, namely the Boreal and Tethyan unpublished data), the Digne rrea (Erba, 1990) and the Reahrs (Arkell, 1956) characterized by differences in Provengal Plateau (Lozx, 1995) are taken into accounr faunas and floras. Ammonite assemblages vary both for calibration of nannofossil versus ammonire events. qualitatively and quantitatively (Arkell, 1956; Cariou, T}re proposed biostratigraphic scheme is compared to 1923). Other benthic and planktonic organisms, such as previously published biozonations and :rnaiogies :rnd brachiopods (Vóròs, 1977; 1979), foraminifers (Gor- discrepancies are discussed. don, 1970), dinocysts (Norris, 1965; Dale, 1983; Riding, Comments on the relative abundance of singie 1984) and nannoplankton (Bown, 1987b;1992; Baldan- taxa with refe rence to rhe assemblage composirion zt er a1., 1995) show a clear differentiation in the two and/or to preservation problems are also given in order Calcareous Nannctfossil erents in Loaer and Middle Jurassìc i15

7 Colma 14 Colle di Sogno b 22 Valle Adrara 30 Ponte Zanano 38 Brasa

I Corn di Canzo 1 5 Torfe de Busi 23 OLera 31 Valle N4orta 39 Corlor

9 [.4a9 io l6 Caricatore 24 Vaiìe Nesa 32 Valle Cfisto 40 Camplone

4A pe Turati 10 Alpe Vivaio 17 ì\4olvina 25 Pradalunga 33 Va e VÌl a 41 Piovere 5 Val Cepelline 11 Strada Forestale 18 Monte Domaro 26 Viganò 34 Va le Cailina 42 Presagio '( 5 Vdr Cepellire-b 12 Cava di C.sa.a '19 I ingorretro 27 Viadaìica 35 Bedolè 43 Val di 6 Va Varea 13 Civate 20 CoLle Pedrino 28 Oregia 36 Valle de Lupo 44 Fostaga ,,/}{ 6 Val Varea-b 14 Co è di Sogno 21 Pradalunga 29 Fiume Gomblo 37 Bocca L4agno

N Ti< V>E ffi Structural high s r,,2 sasin s.t. 0 20 k11

Fig.2-l\{apoithetnaitlJurlssicclutcropsrncllocirtiono1thestudiedscctionsirrtlreLorllll.rrc to better characterize the Jur.rssic- nannofossil assem- complex paleobathyn-ret11- is reflected br- condensed and I.l'-.5'" ,o". ^f.^ .L" T T,..1..,.-Marche and Lombardy Basins. incomplete sequences on the highs. rnd thick, contrnu- ous sequences, with severll resedìmented 1eve1s, in the depressions (Fig. :). The sÌopes are characrerized b1- Geological framework. continuous sequencesr l'ith intern-rediate thicknesses and minor resedimented 1evels. Within the Mediterranean Province, the Umbria- Subsidence and sea level re:rched their meximum Marche (Fig. 1) and Lombardy (Fig.2) Basins were cho- during the Toarcian, when :rrgillaceous sediments were sen as reference areas because of the continuity, good deposited throughout the b:rsin. The drifting ph:rse exposure and good ammonite control in the Lower :rnd occurred in the Middle Jurassic, w1-ren siliceous sedi- Middle successions. Moreover, tl-ie;- represenr Jurassic nrenr.ttion became predonrin.rnt, rel,rred ro.r urrior t$'o key areas for understanding the evolution of the increase in abund:rnce of r:rcliolarians. A great lateral 1Ve'r crn Ter hv. drrlins rhe Trrr,rssic. The srrrdied secrions -*.,..1r....J*' facies variability persisted during the Late Iur;rssic, n{.ren. are located different serrings rnd constitute ideal in er entu.rlly the depo.ition.rl p,rrtern becrrrre predorri- transects from basins ro plxtfornls. Al1 the information nantly calcareous :rnd more uniform as m:rrked bl. tl-r. concernirlg these sections, including their age, geologi- Maiolica limestones. c.rl retting. thickne:r rnd nunrber of .rn.il1 zed *rrnples are sumlnarized in Tables 1 and 2. ìnmharrlrr Racin

During the the Lorr-rb:rrdy Basin s'.ls prrt Umbria-Marche Basìn. Jurassic oi rhe African ^^-,;---, -t -, ,-^;- ,-d irs ,tru.._ '.'.rs.ìve The Umbria-Marche Basin, located between the tural and sedimentary evolution n'as directly controlled Sillaro Valley to tl-ie North and the Latium-Abruzzi car- by extension:r1 tectonics. The Liassic rifting phase caused bonate pl:rtform to the South, constitutes the southern- the brerk up oi.r fti.1ssic c.rrborr.rte plrrlorrrr ìnro 'rruc- nlosr portion of tlie Northern Apennines (Fig. 1). The tural highs and troughs. These were bounded b1' sl.n5scl- l,,,r,(r)rrr :- ul^-i-;-,, -,1 ;- ,L- F.rrlr lurrcric. when extensional imentary faults controlling facres distribution during the tectonics, related to the opening of the \lestern Tethys, Jurassic. As in the lJmbria-M:rrche Basin, sedimentation .--^l'. ..'l -Lr ' l--^.1. drowninp rhe r (equence\ Pi uurl\\ u rrL ur lrrr\ 'rnuy rnd of C.rlc,rre .rr.' "' f.ioLìr,b "/ lif f-t-"..irt.,-l' "rr,'' ) .'^..]"...J '- M:rssiccio c,rrbonate pl:rrform (Farin.rcci et al., 1981; were deposited on structurrl highs, whrle troughs are Colacicchi et al., 1989; Cresta et al.. 1989). The rifting characterized by thick :rnd continuous sections, with and subsequent subsidence phase ied to a heterogeneous frequent turbidites of peri-platform carbonates. ph1'siography of the basin with structural highs and During the Li.r'*ic. r dccpening trend begln. prob- rroughs connected by variously inclined slopes. This .rbly r.hted ro the beginnirrg of oce.rnic.pre,rding. Sedi- 346 E. Mattioli G E. Erba

Time My easlem poftlon 159.4

176.5

180.1

l--l vUS = Marne di Monte Serrone

Fio I Litho- and chronostratigraphy of the studied units in the Umbria-Merche and Lomberdy Basins. Drfferent types of sections in the LJmbria Marche Basin were distinguished according to Colacicchi et al. (1989). Time scale after Gradstein er al. (1994). mentation rates decreased and condensed sequences - nutty to white micritic limestones, with some detritic (Rosso Ammonitico facies) were deposired in the west- interbeds and chert in layers or nodules (Corniola ern part of the basin. In contrasr, in rhe eastern parr, IJnit), Sinemuri;n ro Donreri.rn in agel sedimentation rare increased due ro calcareous turbidites - marlstones and argillaceous marlstones, yellow to (Concesio Fm.). The generation of turbidites s'as prob- dark in colour, with calcarenites in rhe more expand- ably rel,rred ro a renewed tectonic acriviry along rhe ed sections, usually including black shale leve1s Garda fault escarpemenr, which separared the Lombardy (Marne di Monte Serrone Fnr.;, Eerly Toarcian in agel Basin from the Trento Plateau (Gaetani, 1975). The dep- - nodular marlstones and limestones, red ro greenish, osition of thin turbidites continued throughout rhe with clay contenr decreasing upward (Rosso Middie Jurassic (Sogno and Concesio Fms) (Gaetani, Ammonitico Unit), Middle Toarcian to Late Toarcian 1925; lVinterer & Bosellini, 1981; Castellarin & Vai, in age; 1.982 Bersezio et al., 1996; Picotti 8r Cobianchi,1996). - whitish to red limestones, containing a variable In the Middle Jurassic biogenic siliceous sedimen- amount of bivalve shells and occasionally chert (Cal- tation replaced carbonates, and only in the latest Juras- cari e Marne a Posidonia Unit), Late Toarcian to Errl)' sic did calcareous sedimenration resume, as documented Bajocian in age; by the Maiolica limestones. - whitish limestones with abundant chert in iayers and ribbons and, in the more expanded secrions, turbiditic beds (Calcari Diasprigni Unit), Bajocian to Kim- Materials and methods. nrerirlqien in roe

The srr.rriprenhic framework of rhe studied litho- In the Lombardy Basin calcareous nannofossils logic units of the Umbria-Marche and Lombardy Basins were investigated from the foilowing lithotypes (Fig. a): is given in Fig. 3. The studied lithologies, in the Umbria- - grey to dark grey marlstones and marly limestones Marche Basin, comprise (Fig. 4): with chert in layers and nodules (Moltrasio Limestone Calcareous Nannofossil eoents in Loraer and Middle Jurassic 347

Fìo,1 Age and main lithologic Umbria-Marche Lombardy chrrrcterr ol the unit. stud- Lithostratigraphic Lithostratigraphic ìed in the Umbria-Marche Main lithologic characters AGE Units Unils AGE and Lombardy Basins. z z z z limestones with F< chert lenses, cherts cherty 3 preparation retains Calcari diasprigni nd Radiolariti technique C) nodules md limestones O q a layers q rhe original assenìblage and per- a z z rographic composirion. Obser- F O O p vaicolored vations were performed using a I marlstones and :l light polarizing microscope, at hmestones limestones with z Calcari e Mame a with chert z abundant 1000X to 1200X magnification. Posidonia nodules, lenses 7 Posidonia shells a j and beds j The scanning eiectron mlcro- a scope was used only for select- z KOSSO uiil umest( z ed sampies Amonitigg and mùly to document preser- O ú";; limestones nodular Rosso Amml U O Lonbardo vation and nannofacies. -- Monte grey to brown ìimestones and I ,teci(-Jhd6 I F Serrone milly limestones I bt""t-."t'"È F z z grey to lrght Mo z brown limestones z with marly layers O O Previous works on Jurassic O interbedded O qU) a regularly bedded A) nannofossil biostratigraphy. z z É grey to light z D brown J micritic o j Comiola limestones, with A[rer the pionerisric cheft horizons in J Èt papers on nannofossil the lower part Èl Jurassic biostratigraphy (Stradner, I 96ll regularly bedded Èl Prins, 1969; Amézieux, 1972; z duk-grey marly z limestones F Barnard Hay, 1974), several È & investigations have been carried z z massive limestone ottt in order t., r.r.tvide bio- Calcare Massiccio of cilbonate plaffom zonations applic.ible in various areas. Recent synrheses of Jurassic nannof ossil schemes and Gardone Val Trompia Limestone), Sinemurian to (Perch-Nielsen, 1985; Bown, L987b, 1996; Bown et al., Carixian ìn agel 1988; de Kaenel et aI., 1996; Bown & Cooper, 1998) - grey to light brown limestones and marly interbeds highlight the increasing importance of nannofossil bios- (Domaro Limestone), Domerian in age; *-^*:--^^L-.Lrdll6r4Prrjr', - dark grey and green marly claystones and black shales, Investigation of calcareous nannofloras in Italian tr..ì., T^.*^;-- ;- ^--. sections was initially sporadic, but in the past decade - reddish nodular marlstones and limestones (Rosso nannofossil biostratigraphy has been carried out on a Ammonitico), Toarcian to Early Bajocian in age; large number of successions and samples, especially in - varicolored marlstones and limestones with some Northern and Central Italy, resulting in the proposal of chert in lenses, beds and nodules (Sogno and Conce- a few schemes (Bralower et al., 1989; Cobianchi, 1990, 1,992; sio Formations), Toarcian to Bajocian in age; 1992; Reale et al., Baldanza & Mattioli, 1,992b). - green and red chert with few marly interbeds (Radio- More recently, detailed studies of sections in the Umbria-Marche Basin (Barrolini et al., 1995; Mattioli, lariti), Bathonian in age. 1995; Nini er a1., 1,995; Stoico & Baldanza, 1995) and in the Southern Alps (Erba, unpublished data; Sciunnach Samples were taken at regular intervals, from & Erba, 1994;Bersezio et a1., 1996; Picotti & Cobianchi, nricritic limestones and/ or from marlstones, trying to 1996) contributed to the establishment of a biostrati- avoid the detritic levels. Depending on the accumulation graphic scheme for the Lower and Middle Jurassic of the rate, sample spacing varies from a few decimeters to one Mediterranean Province. meter. Only a few sections, on which quantitative analy- ses were performed (wirh an asterisk in Tabl' | \ -'"a sampled every 10-20 cm. Proposed biostratigraphy. Samples were prepared by simpie mechanical breakage of a small amount of rock, dilution with dis- Nannofossil events. tilled water, spreading onto a cover glass and drying in a The synrhesis of nannofossil events recognized in stove. Cover glasses were attached to slides with Cana- this work is presented in Figure 5, where first occur- da Balsam or Norland Optical Adhesive. This simple rences (FOs) and last occurrences (LOs) are caiibrated 148 E. Mattiolí & E. Erba

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f -.t ol II.r l.l lI il-l--i-ia 3-^!.".-.^al -_?aa.iee"ooúoro > - é '^; - É É é i é c c c È ; È è É É É i,è c c = + =q =.^--??^-??^z ? ? ? y9.? ? y.'"-.? ? z ? ? P 3 3 e 3 aÀ^^ ac -ò I tl .:

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?c????qqqq?qq?qqqqqqqqqqqq J i ,ì Fgo^ .eÈ 5î .'+ v2=^ e- i+= !d ;; C^piÌìì=^ .i;.; c^ ,ìi "->Èr=-^É =ea_s,iz:aÉg* eÈ+.":; -ÉEl - .::r Ée= Ei;rÈuq-r ; È iÉ *s; - *i9ess EEai!: *;;! É;E AiÉÍ ; i 3'a's;;;11 eà3,as- e ò= s5- À=3 * ú, O cS nh\MO -d -,S + r.9r€óO -N

L Y,Z.-P.+:e:ì=-.::i*j,iE;Éu:; i=12=* r+t i à Èr i;L+= f, c C-: --- N '. ?+ : À i 2 ,t 1 i * "r =- - =.2 Y í ! c - I ? !. -j-:=--".==c- 12.> = = . - 7 - i -= - íz ;-- -_-ù=-+::-j= 'i =C = i - = = -. : L Í j .= i, v | ó - - z 1 ' : î z: ú ' = - -- ,:=:= = =,Y:Fi i:-Î tÈ. 1i7:.í+7E=i5-\'- ) 7 : - - - i u. Zi=î"i=zZgEÍ=; :-:=it.a\..t"=ii7'j,j -: - e 7 óÀ:1LZ==4È;* -a ....-rc:==.a-zY.=:=--a == z-71,i-.,.,74-'1- u :=:: i; a: z ; :i; k- ú î= z; o "!:4 8 n -t;-E-.=E.,-j-;ì1=?í+:ù;EÉ - \J=. E.ú 9..: , rL " - = - ;Ét:Ei3É-:Ev,ú,= ;:z==t=t=aú.===ii:E*:f":-z=)=.!-=====Ei--J " ri j 350 E. Mattioli & E. Erba

with ammonite biostratigraphy. The study of several sec- FO Tubirhabdus patulus Prins, I969 ex Rood et al., 1973 tions from different basins allowed the testing of repro- Lozar (199,2) calibrated rhis event ro rhe Flerran- ducibility and reliability of every biohorizon. We pro- gian angwlata Zone in the Delphinese area. Although pose here a sequence 47 main evenrs (36 FOs and 11 ol reported throughout the Lower Jurassic, in the studied LOs) for the Hettangian-Bathonian interval. These sections this taxon is rare and discontinuous. Therefore. events are based on diagenesis-resistant taxa that are fre- the reliability of this evenr is limited. quent to common in the studied sections and, thus, are even easily recognized in diagenetically altered material. FO Parhabdolithus liasicus Deflandre, 1954 A further 12 events (11 FOs and 6 LOs) were Bown (1987b) considered P liasicus be repre- identified, but are plotted in a separate coiumn because to sented by two subspecies: P liasicus distinctus and P they are based on taxa displaying very 1ow abundance. liasicws liasicws.In the present work the are F{owever, despite their rarity, these biohorizons were two subspecies not distinguished due recognized in all the studied sections. to difficulties in observation of the Twelve additional events (4 FOs and 8 LOs) central process, sonerimes as a consequence of dia- require further control before final incorporation in the genetic modifications. Cobianchi (1992) observed P. h.a- proposed biostratigraphy. In fact, taxonomic problems sicws distinctws from the Sinemurian upward. This taxon must be cleared and some taxa àre characterized by rare is very rare and discontinuous in the studied areas and sporadic occurrence in the studied sections. throughout the Lower Jurassic. Every event is here discussed in stratigraphic order, from bottom to top. We discuss the taxonomy FO Mitrolithus elegans Deflandre, 1954 when needed and compare our findings to stratigraphic Lozar (1992, 1995) found this evenr in the Lower ranges reported in the literature for different palaeogeo- Sinemurian of Southern France. Cobianchi (1,992\ realms. All taxa discussed are iisted in Appendix ?:tnnt. reported the FO o{ M, lenticwlaris in the Upper Sine- murian of the Lombardy Basin but the photographed specinren (Fig. 20, n) seems referable to M. e/egans, FO Crepidolithus timorensls (Kristan-Tollmann, 1 9BB) Bown because of the presence of a spine extending from the in Bown & Cooper. 1998 basket-shaped distal shield. Also Bovzn & Cooper SmaII Crepidolithus forms have been noticed in the (1998) recorded this species as rare and sporadic from lowermost Jurassic (Hettangian-Sinemurian) ìn the the basal Sinemurian. In the studied secrions, M. elegans Tethyan Realm (1992) by Cobianchi and Lozar (1992, is very rare and discontinuous from the base of the 1995). Recently Bown & Cooper (1998) gave a ?Sine- Pliensbachian to the base of the Middle Jurassic. The murian distribution for C. timorensis, probably the same appearance of this protolith coccolith with a tall distal as the small Crepidolithus of Cobianch; (1992). shield corresponds to the entry of the genus Mitrolithws. Bown (1982b) interpreted the occurrence of M. elegans FO Crepidolifhus crassus (Deflandre, 1954) Noé|, 1965 in sediments younger than Early Toarcian as due to Crepidolithus crtssus is a very solution resistant reworking. taxon, although often subject to overgrowth. Lozar (1992, 1995) found C. oassus in the Hettangian liasicws FO Mitrolithus fansae (Wiegand, 1984) Bown & Young in Zone ol the Delphinese basin, which is a very old record Young et al., 1986 with respect to other literature data (Late Sinemurian; In the Bosso section (Umbria-Marche Basin) ,41. Bown & Cooper, 1998). It must be noted that in Central jansae is present from the raricostatum Zone of Late Itaiy its presence was not observed in sediments older Sinemurian age (Mattioli, personal observation) but than the Sinemurian/Pliensbachian boundary (Mattioli, older sediments were not studied. personal observation) and in the Lombardy Basin This species is easily recognized, is not solution Cobianchi (1992) reported this taxon from the upper- susceptible and is charaterizedby continuous and com- most Sinemurian upward. C. crassus is recorded contin- mon occurrence in Pliensbachian through Lower Toar- uously from the Pliensbachian upward but becomes cian, where it is one of the principal components of the cuite abundant onlv in the Toarcian. assemblage. Some discrepancies exist in the literature

Synthesis of the calcareous nannofossil events in the Early andMiddleJurassic of the Umbria-l\4arche area, Lonbardy Basin and South- ern France. The events, FOs and LOs, are subdivided into: "main events" commonll' atr6 found in most of the studied sections; ""rttu "rare species events", referred to rare but ubiquitous taxa; "events subject to further investigation" referred to taxa requiring further taxonotnic studies and/or spxrse occurrence. The number on the left hand side in each column corresponds to the number of FOs, on the rieht hand side to LOs. Time scale after Gradstein et al. r'1994). Calcareous Nannofossil eoents in Louer and Midd.le Jurassic 351

NANNOFOSSIL EVENTS STAGES Ammonite Zones à main events rare species events events subject to further a 36 I 11 u 4 investisation 8 159.4 z. U t lqf I f L t64.4 wiedmannii z U -C. z F M L ztgzag LCO Discorhabdus spp. _ 169.2 -W. barnesae parkinsoni

SAr0nînna

J z subfurcatum O C. superbus - H. magharensis - humphriesianum L. CTASSUS

sauzet 'large W. britannica 'W. manivitae o J Iaeviuscula

-W. aff . manivitae discites 'W. aff . contracta T. sullivanii 116 --IV. communis C. pranulatus 'W. britannica "7. paîulus B. novum, - o concavum L. sipillaîus - S. cruciulus D lt. ltncntI z B. prande- L. umb"riensis - z murchisonae J B. dubium- L. marserelll". () L..barozii- opalinum -t7. mapharensts 180 (n 'W. coitracta C. cavus M. elegans C. poulnabronei P. Iíasícus a aaIensis neneghini -rR. incompta 1seúdoratl. À C. cantaluppii- small CaLyculus p M. lenticularis criotus erbaense 'D. sullivanii z variabilis B. depravatus 5 bifrons

ts serpenttnus M. jansae - J tenuicostatum 89.6_ -8. Ieufuensis lowet -8. nrínsii '5. sprnatum 'L,'L.fro4oi Umonensrs ,L. C(IVUS -L. pramtgentus mnrgaritatus z ln. grond" È (J stokesi J z davoei I

X P. robustus ì ibex Jo C. pliensbachensis LB. novum JAmesonl ,$. orbiculus 95.3 )ù crucrulus '8. aff. B. dubium Crassus )M. Lenticularis z rancosîatum -M.-L. orynolum lenticularis obtusum îurnerr z semicostatum pliensbachensis 201.9 J bucklandi -'C. '.t11.' iansae z s angulata Miirolithus elegans o small Creoidolithus z liasicus 'Creoidoliîhus crassus ? f- r planorbis zo5.'7 Tu6,r!#!ti:^r"r'llk!i,,, 352 E. Mattioli €" E. Erba concerning the FO of M. jansae. Some of the authors specimens of Similiscwtum aoitum described and figured agree that this event is dated as Late Sinemurian (\7ie- by de Kaenel & Bergen (1993) display srrong similarities gend, 1984; Young et al.. 1986; Bown, l98Zbt Bown er with S. orbiculws and, therefore, we consider S. aaitwm a al., 1988). Whilst Lozar (1992, 1995) and Bown tr junior synonym of S. orbiculus. Cooper (1998) found this event in the Lower Sinemuri- S. orbiculus was found in the lowermost Pliens- an. Different stratigraphic distributions may be related bachian by de Kaenel tr Bergen (1993), but in Por- to migrational effects. In fact, Bown (1982b) showed tuguese sections they reported an older occurrence of S. that this taxon is a char:rcteristic componenr of Tethyan cruciulus with respect to S. orbiculzs (in agreement with our findings observed nannofloras, while it is rare in Northern Europe, and from Central Itrly), whilst they the opposite s.equence of events in Morocco. probably only lived there spor'rdically. This evenr is considered highly reliable and reproducible in the Tethys. FO Biscutum novum (Goy, 1979) Bown, 1987

FO Crepidolithus pliensbachensls (Crux, 1984) Bown, 1987 B. nooum first appears in the Lower Pliensbachian in Italy (Fig. 6) and is never abundant in the assemblages This species was only recorded in the Bosso sec- until the end of the EarlyJurassic. It is not excluded that tion (Central Italy) at the base ol rhe quadriarmatum (: this may result from poor preservation. In the studied jamesoni) Zone, basal Pliensbachian (Mattioli, personal areas, this species is an importrnt consriruent of Toar- observation). An older occurrence is, however, reported cian assembiages characterized by increases both in in the literature (Early Sinemurian; Bown, 1987b; Bown abundance and diversity of the fan-rily Biscutaceae. 8r Cooper, 1998). The occurrences reported by various authors are generally consistent with the It;rlian record (Prins, 1969; FO Similiscutum cruciulus de Kaenel & Bergen, 1993 Barnard & Hay, 1,974;Crux, 1984) with the exception of The entry of S. cruciwlws was calibrated to the the later record of Bown & Cooper (1993) and de Early Pliensbachian (quadriarmatLl.m = jamesoni Zone) Kaenel 8r Bergen (1993; Fig. 6). in the Bosso section (Umbrra-Marche Basin, Mattioli, personal observàtion; Fig. 6). FO Biscutum dubium (Noé|, 1965) Grùn in Grùn et al., 1974 In the published data, disagreement exlsts The FO of B. dubtum was dated as earliest Pliens- berween the generl Palaeopontosphaera and Biscwtum. bachian (quadriarmatwm = jamesoni Zone) in the Bosso Recently, de Kaenel Er Bergen (1993) revised rhe Frmily section from the Umbria-Marci-re Basin (Mattioli, per- Biscutaceae, introducing a new genus, Similiscutum, rep- sonal observation; Fig. 6). This taxon is never abundant resented by various species. The results of this accurete in the assemblage, probably due to diagenetic modifica- work, are difficult to apply to the studied sections, tion of the assemblages and dissolution of delicate because: 1) Biscutaceae are represented by very solution species. B. d,ubiwm differs from B. nolum in its smaller susceptible taxa and the preservation of the studied size, more elliptical shape and wider, subrectangular cen- material is often poor; 2) with the light microscope it is tral area. Due to taxonomic uncert.iinties end preserva- impossible to determine the subtle differences among tion problems, little agreelnent exists for the FO of B. the different species introduced and discussed by de dubìum (Fig.6). Kaenel & Bergen (1993), with the exception of S. crwci- ulws and S. orbiculws. pliensbachensis Although the taxonomic relationships between tO Crepidolithus (Crux, 1984) Bown, 1987 the genera Similiscutum, Palaeopontosphaera and Btscu- In the Bosso River rrea, this species disappears rn tum are srill under consideration, the FO of radiating the mid Lower Pliensbachian (gemmellaroi Zone : ibex plrrcoliths was dated by different authors as Late Sine- Zone; Mattioli, personal observation) . A sirnilar distri- rnurirn or Early Pliensbachian (i.e., Palaeopontosphaera bution is given in Bown Er Cooper (1998). The relative- úeternd, Prins, 1969; Biscutwm dwbium, Crrx, 1.987; Bis- ly short stratigraphic renge of this species, restricted to cutum novum (: S. cruciulzs), Bown, 1,987b; Similiscu- the Sinemurian-Lower Pliensbachian makes C. phens- twm cruciwlus, de Kaenel & Bergen, 1993). This repre- bachensis a very good m.rrker, derpite of its rarity. (1.992) reported this species as rare and sents therefore a solid event that approximates the Sine- Cobianchi murian/Pliensb:rchian boundary worldwide. discontinuous until the Toarcian in some sections of the Lombardy Basin. However, the specimens figured b;' Cobianchi (1992; Fig. 22, t and l) as C. pliensbachensis FO Similiscutum orbiculus de Kaenel & Bergen, 1993 seem referable to C. crassus. Reale et al. (1992) reported The FO of S. orbiculazs is observed in the Lower this taxon as discontinuous and rare in the Toarcian- Pliensbachian (quadriarmatum = jamesoni Zone), just Aalenian of some Umbri:r-Marche Basin sections. How- above the FO of S. cruciulus in the Bosso section (Cen- ever rhe.rrecinren.. "ttril."t"d tn l- nl ìen5fi41fir'n5j5 tral Iraly, Mattioli, personal observation; Fig. 6). The should be attributed rc Twbrrhabdus patulus. In addition Calcareous Nannofossil eztents in Louer ancl Mitldle Jurassic 353

to the taxonomic discrepancies discussed above, res'ork- observed in the Lower Pliensbachian (gemmellaroi Zone ing must be taken into account for the discrepancies on : ibex Zone; Mattioli, personal observation), jusr above the LO of C. pliensbachensis. the LO of C, pliensbacbensis. Because the LO of this taxon has been consistently dated as micl Early Pliens- LO Parhabdolithus robustus Noè|, 1965 bachian (Bown & Cooper, 1998), thrs evenr may be con- In Central Italy (Bosso secrion), this event is sidered highly significant and reproducible.

AGE

z Q U a a

J z Z J

z ,) O M ) F ffi B. depravatus

U il 6 U) '|] 3 f z 7

,-.1 O 3 KW, a z z /-^À J Q W W B. grande B. Jinchii ., 1 810 z l0 4 fI>\ /

Fig. 6 - Drstriburion of the most important species of the genera Biscutum andSimiliscutum. Biscutum t[[. B. fìncbii Cobianchi 1992 is included in B. finchii. In Bown (198/b), S crwciulus was nor distineuished frorr, B. norum. 354 E. Mattioli G E. Erba

J il,

z M I ;

9 E tl -? 81 .l z o Q L velatus L. umbriensis L.6-8.5i W.5.5-?.5 pm Z L. 3.5-5;w.3.3'4.5 pm L. frodoi I L.4-4.8;W. 3.E-4.5 [m L. crucicenîralis L. barozíi L.5-7;W.4.5-ó pm 3.5 !m L. 4.5-5.5; rY. 4-5 !m L. sigillatus L.5-6.5; W.4.5-6 !m

Boreal F------Tethvan I Prins, 1969 4 Hamiìton, 1917',1979 (" P. veternal 3 Reale et al., 1992 2 Crux, 1987 5 Young- et al,, 198ó 9 Stoico & Baldanza, 1996 (* Iitharingius sp. Hi 3 Bown, 1987b; Bown et al., 1988; 6 Bown, 198?b, Portugal ,, "lztharíngius.sp.B), 10 de-K-affiì et al., 199ó Bown 7 Cobimchi, & Cooper, 1998 1992 work

Fig. 7 - Distribution of the most important Jurassic species of the genus Lotharìngius

FO Biscutum grande Bown, 1987 ic marker. Bown (1987b; reconstrucred a distribution B. grande first appears in the Upper Pliensbachian essentially restricted to the Tethyan Realm. The quite (la'r,inianwm : algoaíanwm Zone) in Central Italy consistent occurrences in the literrture (Fig. 6) make of (Bosso section; Mattioli, personal observation) (Fig. 6). B. finchii a good marker. This event is usually dated as Late Pliensbachian, although its first common occurrence seems to approx- FO Lotharingius pridgenius Bown, 1987 imate the Pliensbachian/Toarcian boundary. This species In Central ltaly, rhis species first occurs in the is never abundant in the Upper Pliensbachian. B. grande laainianum Zone (: algoaianwm Zone) of middle Late can be considered a characteristic constituent of Toar- Pliensbachian age (Mattioli, personal observation). This cian assemblages of the Tethyan Realm and, according to entry corresponds to the first appearance of the genus Bown (1982b), occurs only rarely or not at all in some Lotharingiws (Fig. Z) . FIowever, L. primigeniwr rs nor eas- Northern European areas. ily distinguished from L. haffii in poorly preserved material, and according to Bown (i98Zb) it is not possi- FO Biscutum finchii (Crux, 1984) Bown, 1987 ble to exclude that L. primigenius represents poorly preserved specimens of L. haffii, in which the inner cycle This event occurs in the Upper Pliensbachian of the distal shield was dissoived. (lauinianum Zone) in the studied sections (Fig. 6). B. finchii is never abundant in the assemblage, but the'rela- FO Soi/aslfes lowei (Bukry, 1969) Rood et al., 1971 tive ease of identification, because of the peculiar shape and size of the central area, makes it a good stratigraph- The entry of the genLrs Sollasites in Central and Calcareous Nannofossil eoents in Lower antl Middte /urassic 35r

AGE Fig. 8 Dì.trrburron oi rhe mo'r itnport.rnt 'pecics oI rhc gen- L ert Calyculus tnd Lariqo z lithus. U O

E p o ! E FO Lotharingius umbriensis Mal- ó J I 6 tioli, 1 996 é L z l This species appears ln z M I the Upper Pliensbachian J (ema E ciatum Zone) tn the Umbria- llI Merche area lFig. Z) shonly L after the FO of L. haffii, and represents a z link in the evolutionary lineage U M from the most 6 ancestral Lotbaringius and the F most complex shield strucrure E 34 of the genus V/atznauert.a (Mat- tioli, 1996). 9 'IILJ TriT u I l./ u1 JI C. :f Z llrl superbus FO Lotharingius frodoi Mattioli, M :anÍaluppii 1 996 () lio C. poulnabronei I 3l In Central this z Italy u taxon I { Tethyan I first occurs in the upper* ! 5 Hmilton, 197? rrrost Pliensbachiln (emaciatum ó Bown, ^ 198?b, Portugal Zone) (Frg.71. It is trequenr in Boreal D 7 Reale et a1., 1992 8 Perilli lu Goy et al., 1994 Toarcian and Aalenian assem- z 9 Cobianchi, 1992;Erba & q Cobianchi, 1989 blages. 2 Nl.aa. tssu 10 Stoico & Baldanza, 1995 (^ transitional f f Ca | I oms lyculus/Carino I it hus, referable to l*4 r crux, t984: le8? C. poulnabronei) 5 I I t1 de Kaenel et al., 1996 FO Lotharingius barozii Noélt, ycuLus 4 Bown, 1987b; Bown et al., l98El spp. t2 present work 1973 Ihrs species appears in Northern Italy approximates the Pliensbachian/Toar- the uppermost Piiensbachian (Fig. Z) and is rare and cian boundary. This taxon is usually rare and mainly usually discontinuous in rhe studied secrions. As in the occurs in Lower Toarcian sediments. As it is very solu- case of L. haffii,whrch displays a sporadic earlier occur- tion susceptible, the central area strucrures are often rence in Portugal (Fig. 7; Bown, 198/b), in the literature dissolved and specific determination is hampered. Its this event is generally correlated ro the Pliensbachian/ presence, according also to Bown (1982b), is an index Toarcian boundary. of good preservation of the study material, as the central structures of Sollasiles species are only retained in FO Eussonius prinsii(Noé|, 1973) Goy, 1979 well preserved material. This couid account for the dis- In the Umbria-Marche sections this evenr occurs crepancies existing in the literature about this event in the uppermost Pliensbachian (emaciatum : spindtum (Crux, 1984; Bown, 1987b; Bown er a1., 1988; Zone); however, this species is rare and dissolution sus- Cobianchi, 1990; Bartolini et al., 1,992; Reale et a1., ceptible, and this may accounr also for the discrepancres 1,992; Mattioli, 1 993). observed in the literature. Bown (1987b) discussed the synonyms and ranges FO Lotharingius hauffii Grún & Zweili in Grùn et a|.,1974 oî B. prinsii. This aurhor recorded B. prìnsii as rare and discontinuous from Lower Pliensbachian This very distincrive evenr occurs in the upper- rhe (ibex Zone) in Portugal. The same distribution most Pliensbachìan (emaciatwm Zone) ín the studied is grven by de Kaenel & Bergen (1993) in Moroccan areas (Fig. 7) and is considered a main evenr, because Z. secrions. haffii is easily recognized and common. L. haffii is in fact an abundant and diagenesis resistant component of FO Bussonius /eufuensls Bown & Kielbowicz, 1gB7 Jurassic assemblages. Apart from sporadic discrepancies In Umbria-Marche secrions this evenrwas (Ftg. 7; Bown, 1987b), this event is generally dated as observed in the uppermost Pliensbachian (emaciatwm = Late Pliensbachian. spinatum Zone), shortly after the FO of B. prinsii. 356 E. Mattioli & E. Erba

Although very ràre and solution susceptible, this species dle Toarcian-Aalenian. Based on the continuity of irs is a typical constituent of Eariy Toarcian assemblages. distribution, L. crucicentralls is considered a good mark- -. ,..^:^^l ^f T^^-.:.^ as*enrbl.rger. FO Calyculus spp. This event was consistently recorded in the Lon'er Toarcian (tenuicostatum Zone) by most of the aurhors The first specimens of the genus Calycwlws were (Fig. Z). Conversely, Crux (1984) dated the entry of the recognized in side view in the uppermost Pliensbachian L. crucicentralls group including L. hauffii, L. crucicen- (concomitant with the uppermost horizons containing tralis and Noellithina prinsii (synonym of Bussonius Emaciaticeras) or in the lowermost Toarcian (Fig. 8). prinsii) as Late Pliensbachian. It is, however, difficult to This event probably corresponds to a significant vertical distinguish the distribution of single species, and it is development of the inner tube of Calyculus. The lack of not excluded that also in the Northern E,uropean sec- structures in the central area of the observed specimens tions studied by Crux L. crucicentralls first occurs in the usually preyents any specific determination, although basal Toarcian. various subspecies may be recognized on the basis of differences in the verticai extension of the distal shield FO Carinolithus poulnabronei Mattioli, 1996 and in the width oI the central rrea (i.e . C. noelae depres- sa and C, noelae recondita).In spite of the discrepancles This species first occurs in the Lower Toarcian in the literature, in the present work the FO of Calycu- (tenwicostatum Zone) of Central and Northern ltall- lus spp. is considered as the most important event for lFip.\^'ò' "./'8). Ir is .r rr.rnsitional form ber*een rhe gener.r the Pliensbachian/Toarcian boundary. In fact, this very Calycwlus and Carinolithus, characterized by a vertically distinctive taxon is solution resistant and common in extended distal shield slightly thicker than in C. superbus and a assemblages of Early Toarcian age. Here we identify the with wider axial canal. (1982) showed rhat the evolutionar;- Iineage FO of the genus Calycwlws with the appearance of diag- Crux betu'een the genera Calyculus and Carinolitbus devel- nostic basket-shaped specimens in side view. oped through a gradual extension of the distal shield and Bown & Cooper (1998) recorded Calyculus spp. reduction as sporadic ìnthe ibex Zone (Pliensbachian) and contin- the of the centrrl opening. Bown (198/b) uous from the Upper Pliensbachian spinatum Zone (Fig. reported the transitional phase between the two genera 8). as restricted to the tenuicostatum Zone.

FO Lotharingius sigillatus (Stradner, 1961) Prins in Grun et FO Carinolithus cantaluppli Cobianchi, 1990 al., 1974 This event was found only in the Tethy;rn Realm. This event is generally dated as earliest Toarcian Cobianchi (99A, 1992) described this species as a transitional form the genera (base of the tenuicostatwm Zone; Fig. 7) ; however, in between Calyculus and Carino some sections the FO of L. sigillatws was observed in the hthus appearing in the Lower Toarcian (tenuicostatum uppermost Pliensbachran (Mattioli, personal observa- Zone) of the Lombard)' Basin. In the Umbria-Marche area this taxon was probably included C. swperbus, rion;. Although r:rre, L. sigillatus is a very charrcreristic into future studies will therefore ascertain its presence in taxon of Lower Toarcian assemblages. Bown (1982b) areas others than Northern Ita1y. assimilated L. sigillatus to L. crucicentralis, but Bown et al. (1988) distinguished the two species. In the present work, Z. sigillatus is disringuished from L. crucicentralis FO Carinolithus superbus (Deflandre, 1954) Prins in Grún et al., 1974 because of slightly smaller dimensions, more reduced central area and evident processes aligned with the major In the Umbria-Marche Basin, C. superbus first axis of the ellipse (Fig. 7). occurs in the Lower Toarcian (tenuicostatum Zone) (Fig. Apart the anomalous early record in Portugal R\

Fic. 9 - Distrihrrrinn .I rhe mort AGE important species of the genus Discorbabdus. Dis corhabd.us aff. D. striatws z L Cobianchi 1992 is included in D. ignotws. De Kaenel & O Q Bergen (1993) Íound Biscu U) Ch tum profwndum in the algo- E rianum Zone of Portugal and ìn rhe margaritatus Zone of Morocco (Middle Upper rrl J Pliensbachian). However, L they include in this new z species both circular and z elliptical specimens. The rrì M forms they figured (plate 3, .l figs. 6 and Z) seem very srml- E lar to D. ignotus. It is nor excluded that they included in B. profwnclum two differ- L ent species, with differenr str.rtr graphicaJ rrnges. disr in- I guishable on the basis of the z elliptical or circular shape. Biscwtum striatunt de Kaenel O M & Bergen 1993 is included in D. striatus. In Portugal 1 Hamilton rhi< F Discorhabdus criotus (1977) Iound E 1 raxon frorn the Upper Sine- nrurien uprrrd tnd D. patu Ius from the basal Middle Torrci,rn. However, the 'pec- (J irnens oI D. ignorus figured a z (plate 2, Íigs. 2 and 9; plate 4, v) . Iigs. 10 and t1) and attrib- z @ uted to the Pliensbachian 5 Ò xabdus st seem to be referable to B. tf U lll' noTkm. "l Boreal rrl v) z I Bown, 1987b;Bown et al., 1988 z J X 2 Moshkovirz & Ehrlich, 1976 (J 3 Hamilton, 1977 4 Young et al., 1986 z I' 5 Bown, 1987b, Portugal Reale etal.,1992 L 6 7 Cobianchi,lggz* rYì z 8 de Kaenel & Bergen, 1993^ U) Discorhabdus ignotus 9 present work

Italy (Fig. 7). Although rare and with delicate central Dactylioceras and below the oldest horizons with area structures, L. oelatus is very characteristic and easy Hildaites (Fig.9). Because rt is the first species of the to recognize. Its abundance increases in the Aalenian genus to appear at the top of the tenwicostatum Zone, the and the common findings in this interwal could explain FO of D. ignotws is proposed as a marker for the some discrepancies in the published data. tenuicostatumf serpentinws Zones boundary (Early Toar- cian). After its FO, D. ignotus is usually rare but FO Discorhabdus ignotus (Gorka, 1957) Perch Nìelsen, becomes quite common in the Middle Toarcian and this 1 968 could explain the different distributions reported in lir- In Central ltaly, this event vr'as detected in the erature. We attribute to D. ignotws only the circular spec- youngest horizons containing ammonites of the genus imens. The discrepancies among various authors (Fig. 9) E. Mattioli & E. Erba

A(lR, z

)

O L

;l f z € - u, Él oI E t# ill W. bamesae l0 lolt L 5 ?@:w 4'ó!ù

L z W. manivifae L: 9 15 W: 1.5 - 1l .z M !m: !m ,i 3 ll. aff. W. manivitue E Lró.5 - 9!m:W:5 - 1.5 !m

L W. brítanníca L:4'9sm:Wil-7gm

z M 4 Hamilton, 1979 f 5 Moshkovitz & EhrÌich, 197ó; 1981 :l U W. C?ntracts Lr5.5 - ? -ó 6 1990 1l lmrwr4.5 !m Erba, Cobimchi, 1992; Cobimchi et al., 1992; Erba I ,' F é Borel Cf &Cobimchi, 1989 i! E 8 Reale e(er al,,al.. 1992 (*I previously nmedW. bames, @pffi Baldmza & Mattioli, 1992a e b; Nini et al., 1995; w. tossactncla W. col zcrcchtt L:4 -; smi W: j - 5 r 5.2-6úa W:4.5 - 5.5 m

'Watznaueria. Fig. 10 - Distribution of the most imporrant Jurassic species of the genus The distribution ol V/atznaueria contracta includes thar of Lotharingiws contrdctus Bown et al, 1988. Watznaueria fossacincta previousll' called.Watznaueria sp. 7 by Cobianchi (1992) and Cobianchi et il. (1992), V/. barnesae by Baldanza & Mattioli (1,992a and b), Nini er al. (i995), Reale et rl. (1992). probably result from both taxonomic uncertainities and species and has siightly different widrh and shape of the differences in ammonite biozonations or palaeoprovin- central area (Mattioli, 1996). cialism. After a careful revision of slides and photographs, the specimens previously referred to as Z. conLrttcLLrs) LO Mitrolithus jansae (Wiegand, 1984) Bown & Young in observed in the Middle Toarcian of Greece and the Young et al., 1986 Upper Toarcian of Portugal by Baldanza & Mattioli (1992a) and those recorded in the Middle and Lower The LO o{ M. jansae has been recorded in the Toarcian respectively by Baldanza 8c (1992b) uppermost Lower Toarcian, but sporadic occurrences Mattioli and Mattioli (1,993) in Central Italy, should be attributed are observed in Middle and Upper Toarcian Italian sec- to W colacicchii. tions (Cobianchi, 1992; Reale et aI., 1992; Baldanza k Mattioli, 1992b). The LO o{ M. jansae can be regarded as a synchronous event in literature, and sporadic younger FO Watznaueria fossacincta (Black, 1971) Bown in Bown & ages are probably due to reworking. Cooper, 1989 'V/. The entry of fossacincta was observed, both in Lombardy and in Umbria-Marche, in the upper Lower FO Watznaueria colacicchri Mattioli, 1996 Toarcian (uppermost part of the setpentinus Zone) (Fig. 'W This species was first observed in the uppermost 10). In the Umbria-Marche area rhe FO of barnesae Lower Toarcian (top of the serpentinus Zone) in Central was previously reported from the Middle Toarcian italy and its appearance corresponds to the entry of rhe (Reale et a1.,1,992;Ba\danza & Matrioli, 1992b). How- gelrus Watznaueria (Fig. 10). This raxon is quite similar ever, the taxonomic characters of the specimens found 'WI in shape to contracta bút is smaller than the type in the Middle Toarcian of Central Italy seem to be Calcareous Nannofossìl eoents in Louer and Middle J urassit 359 slightly different from those of W barnesae. The most figs. 26 and Zl) has to be considered as a synonym of Z evident differences are in the centrai area, still nor com- sullipanii. The distribution of this species seems to be pletely closed rn W. fossacincta, and the relatively restricted to the Tethyan and Pacific Realms. brighter birefringence colours. FO Biscutum depravatus Bown, 1987 FO Discorhabdus sfrialus Moshkovitz & Ehrlich 1976 B. depraoatus is never abundant in the assemblage, D. striatus appears at the boundary between the but is, however, easily distinguishable from other species serpentinus and the bifrons Zones (EarlylMiddle Toar- of Biscutwm, because of its very open central area and cian boundary; Fig. 9). According to Bown et al. (1988) cross structure. Its FO can be considered as an impor- this species can be distinguished from D. ignotus because tant event of late Middle Toarcian age (.oarrabtlrs Sub- of its larger size, completely closed centrai area and zone; Fig. 6). brighter birefringence colours in polarizing light. This event can be considered as synchronous in different FO Discorhabdus criotus Bown, 1987 domains and is therefore a good biostratigraphic marker In the studied Umbria-Marche sections, this event for the EarlylMiddle Toarcian boudary. It is an abundant was found in ammonite biohorizons of late Middle Toar- and characteristic component of Middle Toarcian- cian age (oariabilts Subzone; Fig. 9). Although rare, D. Aalenian assemblages. criotus shows consistent distribution in various areas.

LO Parhabdolithus Iiasicus Deflandre, 1954 LO Calyculus spp. The LO o{ P liasìcus occurs in the Middle Toarcian This group is present discontinuously through the (btfrons Zone) in the study areas. This record is not con- Aalenian (Fig. 8). However, the smaller forms (< 6 prn) sistent with the literature data. disappear in the Late Toarcian (meneghinii Zone). In rhe In Portugal Bovrn (1987b) dated rhe disappear- literature some discrepancies exist concerning rhis ance P liasicus as of distinctws Late Domerian (spinatum event, probably due to reworking. Zone) and liasicus liasicus the LO of P as Carixian The disappearance of the "small" Calyculus is cor- (daooei Zone). Hamilton (1977, 1979) found this event relatable to the LO of Calyculus spp. dated as Late Toar- xt the Lower/Upper Pliensbachian boundary Portu- in cian (erbaense Zone) by Reale et aL (1992) and Baldanza g;il. Bald:rnza & Marrioli (1992a) found the extinction of & Mattioli (1992b), and correlated to the meneghinii this taxon in the Upper Toarcian (meneghtnii Zone) of Zone by Cobianchi (1992). Portugal and in the Lower Toarcian (tenuicostatum Zone) ol Hungary. In Italian sections, Baldanza tr Mat- LO Carinolithus cantaluppli Cobianchi, 1992 tioli (1992b) recorded the presence of P liasicus rhrough the Lower Toarcian, while Erba & Cobianchi (1989), This event was reported rn the Upper Toarcian of Reale et al. (1992) and Cobianchi (1992) found this Northern Italy by Cobianchi (1990; 1992), but Periili (ln species in the Middle Toarcian. In one section from Goy et a1., 1994) found C. cantalwppii in the opalinum Central Italy |'4x111oli (1994) found P liasicus discontin- Subzone of the Fuentelsaz section in Spain (Fig. 8). uously up to the Aalenian. In the Boreal Realm most Authors found P liasi- FO Fetecapsa incompta Bown & Cooper, 1989 cz.r continuous, although rare, through the Lower Toar- R. incompta is :r very rrre raxon but its FO v.as cian (Prins, 1969; Bown,1987b; Bown et al., 1988) or consistently dated as Late Toarcian (meneghtnii Zone; Middle Toarcian (Crux, 1984; 1987) and discontinuous Baldanza & Mattioli, 1992b; Mattioli, 1994; Bown 8c 1954; up to the Dogger (Deflandre 8{ Fert, Stradner, Cooper, 1998). 1963; Thierstetn, 1,976; Medd, 1982). Such discrepancies could be due to reworking phenomena. LO Carinolithus poulnabronei Mattioli, 1996

Carinolithus poulnabronei has a stratigraphic range FO Triscutum sullivanii de Kaenel & Bergen, 1993 restricted to the Toarcian, as it disappears at the base of This species is never abundant in the assemblage, the Aalenian in an interval dated bnly by means of other however its FO can be considered as an important event calcareous nannofossil evenrs (Mattioli, 1994; Fig. S). in the upper Middle Toarcian (variabilis Subzone) in the Umbria-Marche area. This record is consistent with lit- FO Diazomatolithus lehmanrT Nòel, 1965 erature data from the Tethyan Realm (Bown, 1987b; Mattioli, 1994; Sciunnach 8c Erba, 1994; Bartolini er al., This event occurs at the Toarcian/Aalenian 1995). According to de Kaenel tr Bergen (1993), Tiiscw- boundary in the Lombardy Basin and D. lehmann seems tum sp.1 of Bown (1987b) (plate 9, figs. 6-9; plate i4, to be a typical form of the basal Aalenian, at least in the 360 E. Mattioli & E. Erba

L1 Distribution oI thc ol 'pecic' z the genus Cyclagelol haera. o J 'l magharensis is usually rare in al z the studied areas, it can be con- z sidered as a significant component of Middle Juras.ic assem- L- blages. This taxon seems to have a distribution restricted to .L-'r-,L,.^- .-J D^ .:f:c Realms, U U) as it has never been recorded in U) Northern European sectrons lll (Bown, & Cooper, 1998). I 1 Medd, 1982 FO Cyclagelosphaera margerelii 2 Hamilton, 1982; Bamard Noè|, 1965 &. Hay , 197 4; Medd, 1 97 1 3 Bown & Cooper, 1989 The first appearance of this species is an import:rnt event Aaìenian rge, 4 Erba, 1990; Hamilton, 1979 oi Middle ll although the oldest speclmens Cobianchi, 1992; Cobianchi efal.,1992; 3 5 are rare Erba & Cobianchi, 1989 in the studied sections z f Fìg. ll.,) . Sonre discrepancie. 6 Reale etal.,1992 exist in the literarure concerning z 7 Baldanza & Mattioli, l992a,b; Nini et al., ei J 1995; Mattioli, 1994 this enr. ;s ,rlre"dr discussed by Erba (1990). It is not exclud- 8 Reale & Monechi, 1994 C. margereLii ed th:rt the discrepancies.ire D: 5.0 - 6.5 pm 9 present work, Bartolini et al., 1995 due to dif ferenr raxonomic con- cepts and to a little confusion Tethyan Realm. Some differences are observed with related to the presence of other circular \farznauerraceae respect to the distribution in Northern Europe, as in the uppermost Middle Jurassic (i.e. C. deflandrei). already discussed by Erba (1990). FO Watznaueria britannica (Stradner, 1963) Reinhardt, 1964 LO Biscutumfinchii (Crux, 1984) Bown, 1987 Some taxonomic uncertainties exist in the litera- In the present work the LO of B. fincbii is dated ture concerning this species and its relationship with V7 as latest Aalenian (Fig. 6), although a precise disappear- communis, consequenrly diff erent distributions have ance level of this species is difficult to determine proba- been reported (see Erba, 1990, for further details). In bly due to reworking. the present work W britannica is considered a very important marker for the Aalenian/Bajocian boundary in the Tethyan Realm, as it is found in the uppermost FO Watznaueria contracta (Bown & Cooper, 1989) Aalenian or at the base of the Bajocian (Fig. 10). It is not Cobianchi et al., 1992 excluded that the latest Pliensbachian and Toarcian This event is characteristic of the basal Aalenian occurrences for this taxon (HamìIton, 1,979) may be 'V/atznaueria (Fig. 1O). contra.cta was a new combination related to the presence of species of Lothartngrws (see L. for Lotharingius contractus Bown and Cooper, 1,989, frod.oi) with a transverse bar in the central area. because of the presence of a \íatznaueriacean rim in this form. After a revision of the specimens previously found FO Watznaueria communis Reinhardt, 1964 in the Umbria-Marche sections, the writers agree with The relationships between this specie s and V/. bri- Cobianchi et aL (1992) in thrs new combination and dis- tannica were discussed by Erba (1990). The entry of W tribution. communis is considered as a good event of Eariy Bajo- cian age (Fig. 10). FO Hexalithus magharensis Moshkovitz & Ehrlich, 1976 In the studied sections the FO of H. magharensis FO Watznaueria aîî. W. contracta Cobianchi et al., 1992 was found at the base of the Aalenian. Although some Watzn au eri a af f . W c o ntra ct a w a.s rep orted Watz - ^s discrepancies emerge from the literature and H. naueria sp. 2 by Cobianchi (1992) and Cobianchi et al. Calcareows Nannofossil eoents in Lower and Middle Jurassic 361

i iF ruY/S.FNCE BOREAL DOMAI N î] B È S { ,- sÈ; o ì " 3 Bown et al. 1988; Bown & Cooper, 1998 Ìit*qg i = s :*€,=,= î: È: ='È St : : I È Nannofossil Nannofossil Éifi 3 i:*e ÈS=ì É ; ;i s-è dì È : È=ÈÈ F ÈB* È 5 È-È Subzones Zones '. dr: ìo.5ÈÈSè:fÈì;ÈÈg5EÈsESì= Zones and Zonal marke.s -,: a.> > Li a.>?jri lù.i -te d(cjo< XqU È È >ú Subzones

S. hígotíí

P. enigilo

A. helvetica rl w. bamesae I I

P. enigma

IT rl W. nnniyiîoe

S. speciosum

JT 9 W bnlanNîn W. britannica li

NJT 6.

L conrractus NJTth Xfr l" R incompta

I i rur zl D. stnatus

I NJT 7. I D. stríatus

D. striatus

n.rr*i Lrisilrn,r, C. superbus --1 rNJrs L.hauJfii NJr5.i Lfnchii C. impontus L hauffii i- I NJTai Scruciulus t. P. robustus NJT4! P. robwtus

S. cruciulus

C. crusus ') c Ptie^lbachens i s nrr r")r. o,n^oo*,n, sliNJr3 !

M:-eí:Bys_ ]NJT P. liuicus o t Ll S. putrctuldta E

Fig. 12 - Biozonation scheme proposed for Italy and Southern France (Mediterranean Province) compared to the scheme proposed by Bown et rl. (1988) and Bown & Cooper (1998) for the Boreal Realm. Time scale after Gradstein er al. (1994).

'Watznaweria (1992) and as sp. 4 by Erba (1990). This Baldanza et al. (1990), Baldanza 8r Mattioli taxon is here considered as a transitional form between (1992b) and Reale et al, (1992) recorded 'V/. manivitae .W contracta and W mani,t)itae, its dimensions being larg- respectively in the Middle and Upper Aalenian of the er than the rype species ofW contracta (Fig. 10). Umbria-Marche Basin. However, after a revision of the material, these specimens resulted to have dimensions smaller than W manirtitae, and they should therefore be FO Watznaueria aîf . W. manivitae Cobianchi et al., 1992 assimiiated into'Watznauerta alÎ. W m anirtitae. This event was calibrated to the discites Zone (Early Bajocian) . This taxon, never exceeding the length of 9 pm, is considered transitional from'Watznaueria aff. FO Watznaueria manivitae Bukry, 1973 'W contracta to'W manir,:itae (Cobianchi et al., 1992;Fig. Moshkovitz & Ehrlich (1987\ reviewed the taxon- 10). omy of 'W. manix,itae and distinguished it from Mattioli G E. Erba

Cyclagelosphaera deflandrei. In the iiterature these rwo because of the presence of a not completely closed cen- taxa were often assimilated, as discussed by Erba (1990). tral area. .W. mantvitae is easily recognizable and very solution resistant and its FO is regarded as an excellent event of FO Cyclagelosphaera wiedmannii Reale & Monechi, 1994 middle Early Bajocian age (lae.',iwscula Zone) (Fig. 10). Cyclagelosphaera zuiedmannii was originally Baldanza et al. (1990) noticed an increase in size of '\X/. described from DSDP Site 534, the section (SE manioitae occurring in rhe sauzei Zone. As the speci- Quissac .V/. France), Valdorbia section (centrel Italy) and Bihendula mens of maniz,itae of Baldanza et al. are small- ltllo; section (Somalia) (Reale & Monechi, 1994). Calibration er than 9 pm and appear in the Aalenian, they should be .V/atznaueria of the stratigraphic range of rhis trxon is poorly con- considered the same as afÍ.'W maniaitae, strained. In fact, the FO of C. .uiedmannii was correlat- and probably only the specimens which are larger in size ed with the macrocephalws Zone in the secrion (> 9 pn-r) should be attributed to.W. manivitae. Quissac and dated as earliest Callovian. At Site 534, C. raiedmannii was observed in the lowermost sediments above LO Watznaueria alf . W. contracta Cobianchi et al., 1992 basalts and therefore this occurrence cannot be univo- This species shows a short range, restricted to the cally considered as the first f,ppearance of the taxon. Lower Bajocian. In fact, it last occurred in the sauzei Moreover, there is no documentation of the nannofossii Zone, according to Erba (1990). distribution of the Quissac section and it is not clear if this marker is present in sediments oider than Callovian. LO Carinolithus superbus (Deflandre, 1954) Prins in Grùn et Recent studies of the TerminilÌetto section (Bar- al., 1974 tolini et aI., 1995) revealed rhe occurrence ol C. zuied mannii in siliceous limestones attributed base This taxon becomes very rare and discontinuous to rhe of the radiolarian Zone IIAZ 7. The base thrs zone has from the Bajocian upwards and its LO is calibrated to of been equated to the Middl e/Lrte Bathonian boundary as the beginning of the Lare Bajocian (Fig. 8). This event is determined amn-ronites usually placed in the Bajocian (Moshkovitz & Ehrlich, by in sections from Spain (O'Dogherty et al., 1995; B:rrtolini et al., 1995). Revi- 1976; de Kaenel et aI., 1.996; Bown et al., 1988). sion of the radiolarrian biostratigraphy for Site 534 resulted in an updated biostratigraphic age for the basai LO Hexalithus magharensis Moshkovitz & Ehrlich, 1976 sediments. The ULZ 6 Zone was defined on a singie Erba (1990) recorded this event in the parkinsoni sample at 167 cm above the occurrence of C. uiedm'an- Zone (latest Bajocian) of the Digne sections. This dis- nii.Therefore, the FO of this taxon is older than previ- tribution is consistent wirh rhe range given by ously reported and as old as latest Middle Bathonian Moshkovirz tr Ehrlich (1976\ in Israel and Northern (Fis. tt). (1994\ Sinai. Sciunnach & F.rba consider this event as Recent syntheses of Jurassic calcareous nannofos- significant of a Bajocian age, as H. magharensls has never sil biostratigraphy (cle Kaenel et aL, 1996; Bown, 1996; been found in younger sediments. de Kaenel et al. Bown & Cooper, 1998) do not report C. zuiedmannii. (1996) calibrated the LO of Carinolithus magharensis Consequently, the occurrence and/or the stratigraphic between the end of the Early Bajocian and the beginning distribution of this taxon in other areas are still uknown. of the Late Bajocian, shortly after the LO of C. superbus, However, this taxon has been observed in Oxfordian sediments from Southern Germany (Martioli, personal FO Watznaueria barnesae (Black in Black & Barnes, 1959) observation). Perch Nielsen, 1968 Some discrepancies emerge from the literature Tethyan nannofossil zones. about this very distinctive event, as already observed by Erba (1990), probably partly related to taxonomic prob- For the Hettangian-Bathonian interval, we pro- lems (Fig. 10). In the studied sections this event is char- pose here a biozonal scheme consisting of 11 zones and acteristic of the base of the Bathonian (zigzagZone). 15 subzone based on ammonite-calibrated nannofossil The specimens of W. barnesae reported in the events (Fig. 12). Each zone is described in stratigraphic Early Jurassic by Reale et aI. (1,992) and Baldanza Er order: in addition to the definrtion of lower and upper .W. Mattroli (1992b) should be ascribed to fossacincta, boundaries, the assemblages are discussed and the

Fig. 13 - Comparison of calcareous nannofossil events found in Italy and Southern France with data summarized for Northern Europe, Portu- gal and Morocco by Bown (1996) and de Kaenel et al. (1996). The events in bold are reproducible in various areas and allow inter- regional correlations. Time scale after Gradstein et il. (1994). Calcareows Nannofossil eoents in Lower and Middle Jurassic 363

de Kaenel et al., 1996 Time in Ma Italy/S. France 159.4

L.velatu bigotii bigotii igotii bigotii

164.4

Z .pecussaNs I .narTtsonil .l S,hexum .wiedmannii H.cuvillieri A.helvetica U z T.shawensi U) Ì1 U) F LCO Discorhabdus H.cuvillieri 169.2 T.shawensis C. margerelii rrl J S.speciosum octum P.enigma

A.helvetica Acme B.striatum

C.magharensi C.magharensis T.su mantvlrae W.aff.manivitae W.britannica IV.aff.contracta w.corTununrs 176.5 W.britannica Lpatulus LCO Biscurum spp, .mar8eÈelii L.sisillaîús C.impontus/cavus L.umbrien - B.prinsii C.margerelii H.maghare4qis .tiziense .. incompta W.contracfd- l R. incompta C. cavus

,depravatus L. A.depravatus .intermedium

D. criotus .intermedium T. sullivanii acme L.hauffi B, depravatus , criotum

striatus Q,hamiltoniae O. hamiltoniae Stflatum I B. striatum colacicchii M P.grandis P.grandi superbtlt- $. hnchi P. liasicus dis-tinctu s.llnchil , superDus poul . caitaTu-póìi * C. nabronei C. jansae . cruclceÌltralls' L. sigilfatus . 189.6 U ). crucr A. atavus , atavus I tt.- Drorunoum I v) , A- Atavus L. hauflii l U) z ha'rfiii J. ,.sigillatus . llaslcus llar .novus. L.hauffri .lmDontus/cavus , profundum .novus . hduffii ;) (J u) rrì z C. pliensbachensis F I , cruciulus 195.3 J cruciulus . granulatus . lenticularis

z . hamiltoniae hamiltoniae . crassus crassus D à z U) . pliensbachensis 201,9

rl "small" Crepidolithus z P. liasicus

F 205.7 rrì 364 E. Mattioli & E. Erba

chronostratigraphical extent reported. The nannofossil stitutes the most abundant taxon in the assemblage. The zones and subzones are coded with a number, according first occurrences of T. patulws, small forms of Crepi- to the method introduced by Martini (1971) for the dolithus, M. elegans and M. jansae are also observed in Cenozoic, and previously adopted by Bown (1982b) and this zone. Bown et al. (1988) for the Jurassic. Zones and subzones Zone NJT 2 corresponds to the upper part of the are also labeled with NJT = nannofossil Jurassic in the NJ 1 and to the lower part of the NJ 2 of Bown (1987b) Tethyan domain, followed by increasing numbers from and Bown et rl. ltlSS; bottom to top. For subzones, progressive alphabetic let- rers (a, b, are applied following stratigraphic c) the NJT 2a - Parhabdolithus /iasicus Subzone order within each zone. Author: defined here. Definition: First occurrence of Parhabdolithus liasi- Description of Tethyan Nannofossil Zones. cus to \h.e first occurrence of Mitrolithus elegans. Age: Middle Hettangian to the Hetrangian/Sine- NJT 1 - Schizosphaerella punctulata Zone ..t.r,.- h^"-.ì.r-r Author: Bown (1987b). Reference section: Pradalr-rnga section, Lombardy Definition: First occurrence of Schizospbaerella punc- Basin (Lozar, 1995). tulata to the first occurrence of Parhabdolithus liasicus. Comments: This subzone corresponds to the . Age: Triassic/Jurassic boundary to Middle F{ettan- upperpart of theNJ 1 of Bown et al. (1988) and is not glan. correlatable with their Zone NJ 2a. Reference section: Pradalunga section, Lombardy Associated species: Schizosphaerella spp., P. liasi Basin (Lozar, 1995). cus, C. primulus and T. patulus. Comments: The FO of P liasicus has been recorded in the Tethyan Realm earlier (Middle Hettangian; NJT 2b - Mitrolithus elegans Subzone Lozar, 1995) than in the Boreal (Late Hettangian), Author: defined here. Name previously used for NJ therefore the duration oî Zone NJT 1 is shorter in the 2b Subzone of Bown (19BZb). Tethyan Realm. Definition: first occurrence of Mitrolithus elegans to Associated species: the assembl.rge is generally the first occurrence oÎ Crepidolithus pliensbachensis. very poor and the only taxon continuously present is Age: Hettangian/Sinemurian boundary to Early Schizosphaerella spp.; sporadically C. primwlws is also Sinemurian. observed. - Reference section: Pradalunga section, Lombardy Basin (Lozar,1995). NJT 2 - Parhabdolithus /iasicus Zone Comments: in thrs subzone the first occurrence of Author: Bown (1987b) emended here. M. jansae is recorded. The assemblage is still dominated Definition: First occurrence of Parhabdolithws liasi- by Schizosphaerella spp. Subzone NJT 2b does nor cor- czr to the first occurrence of Creoidolithus Dliensbachen- respond to the NJ 2a Subzone of Bown (1987b), whose sls. base is defined by the LO of P marthae and its top by the Age: Middle Hettangian to Early Sinemurian. FO of C. crassws. The NJT 2a is p:rrtly overlapping with Reference section: Pradalunga section, Lombardy the NJ 1 of Bown (1987b). Basin (Lozar, 1995). Associated species: Scbtzosphaerella spp., P hast- Comments: the assemblage is very poor, only cus, C. crtsstrs, M. elegans, M. jansae, C. primulus and Z Scbizosphaerella spp. is recorded continuously and con- patulus.

PLATE 1

Ail light rnicrographs crossed nicols, approxirnatell' X 3000. l. Schizosphaerella spp., sarnple S1 1.30, Genuardo (Sicily), Early Pliensbachian; 2. Schizosphaerella spp., sample FLE 25.10, Fitminata (Ccntral Ital,v), F,arl,v Aalenian; 3. P robusrus, sample PCR 8, Piana degli Albanesi (Sicily), Late Sinemurian; 4. P robustus, sample PCR 8, Piana degli Albanes i (Sicily) , Late Sinemuria n; 5. P liasicus, sample PCR 8, Piana degli Albanes i (Sicily), l.atc Sinemurien 6. M. pulla, sar-nple S 1 1 .3 0, Gen- uardo (Sicily), Eerly Pliensbachian;7. C. pliensbachensis, sarnple PCR 8, Piana degli Albanesi (Sicily), Late Sinenurian; 8. C. oassus, san'rple I'CR 8, Piana degli Albanesi (Sicily), Latc Sinemurian;9. M. elegans, sernplc PCR 8 (Sicily), Late Sinemurian;1.A.,ù[. elegans, sample PCR 8, Piana degli Albanesi (Sicily), Late Sinemurian; 11. M. elegans, sample PCR 8, Piana degli Albanesi (Siciiy), Late Sìnemurian; 72. M. lenticuÌarls, srnrple PCR 8, Piana degli Albanesi (Sicily;, Lrre Sinemurian: 13. S. cruciulus, sample S1 1.30, Genuardo (Sicily), Early Pliensbachran; 14. M. Tansae, sarnple S1 1.30, Genuardo (Sicily), Early Pliensbachian; 15. M. jansae, sample S 1 1.30, Genuardo (Sicily), Early Pliensbach)m; 1.6. M. lenticularis, sample PCR 8, Piana degli Albanesi (SiciLy), Lrre Sinemurirn;17. S. orbiculus, sample S1 1.30, Genuardo (Sicily), Early Pliensbachian; 1.8. B. finchiì, sarnple MBE 2.30, Somna (Central Iraly), Early Toarcian, specinen srnaller than 6 pm; 19. B. fínchii, sample MBE 2.30, Sornma iCentnl Irrlv;, E.rr\' Toarcian; 2a. B. finchii, sarnple MBE 2.30, Somrna (Central Italy), Early Toarcian. Pl. 1 Calcareous Nannofossil er-tents in Lott;er ,tnd Middle ./urassic 165

L Schizosphnerella sW. 2. S chízo sp hnere lla spp. 3. F. robustus 4. P. robustus

5. P. liasicus 6. M. pulla 7. C. pliensbar:hensis 8. C. crassus

9. M. elegans lO. M. elegans ll. M. elegans 12. M.lenticularis

L3. S. cruciulus 14. M. iansae 15. M. jansae 16. M. lenticularis

17. S. orbiculus 18. B.finchii 19. B.finchii 20. B.finchii 366 E. Mattioli & E. Erba

NJT 3 - Crepidolithus pliensbachens/s Zone Definition: first occurrence of Similiscutum crwciu- Author: defined here. Name previously used for lus to the first occurrence of Lotharingius hauffii. the NJ 4a Subzone of Bown (1987b). Age: Pliensbachian. Definition: first occurrence of Crepidolithus pliens- Reference section: Bosso/Burano se crion, Umbria- bachensis to the first occurrence of Similiscutum cruciu- Marche Apennines (Faraoni et al., 1996; Mattioli 8c lus. Morettini, in progress). Age: Sinemurian to earliest Pliensbachian. Comments: This zone corresponds to the entire Reference section: Pradalunga section, Lombardy NJ 4 Zone of Bown (1987b). Nannofossil abundance Basin (Lozar,1995). and species richness notably increase in this zone. Rep- Comments: This zone corresponds ro rhe upper resentatives of the Family Biscutaceae, such as S. orbicu- part of the NJ 2 Zone and to the entire NJ 3 Zone of lus and B. d.ubiwm appear in the Early Pliensbachian. P Bourn (1982b). robustws and C. pliensbachensis disappear. Associated species: dominant Schizosphaerella spp. Associated species: dominant Schizosphaerella spp. and rare P. liasicus, P robustws, C. crassws, M, elegans, M, and rare P liasicws, P robustus, C. crassus, M. elegans, M. jansae, jansae, C. primulus, C. pliensbachensis and T patwlws. C. primulws, C. pliensbachensis, B. grancÌe and T. patulus.

NJT 3a - Crepidolithus pliensbachensis Subzone

NJT 4a - Parhabdolithus robusfus Subzone , Author: defined here. Name previously used for the NJ 4a Subzone of Bown (1982b). Author: defined here. Definition: first occurrence of Crepiclolithus pliens- Definition: first occurrence of Simtliscutwm cruciu- bachensis to the firsr occurrence of Mitrolithus lenticw- lws to rhe last occurrence o{ Parhabdoltthws robwstus. laris. Age: Early Pliensbachian. Ano (i.o..".i.- Reference section: Bosso/Burano section, ' rYv. vr"!"rsrrqtr. Umbria- Reference section: Pradalunga secrion, Lombardy Marche Apennines (Faraoni et al., 1996; Matrioli 6r Basin (Lozar,1995). Morettini, in progress). Comments: This subzone is correlative of the entire NJ 4a and part of the NJ 4b Subzones of Bown NJT 3b - Mitrolithus lenticularis Subzone (1 e8zb). Author: defined here. Defìnition: first occurrence of Mitrolithus lenticu- NJT 4b - Similiscutum cruciulus Subzone laris to the first occurrence o{ Similiscutwm cruciwlws. Age: Sinemurian/Pliensbachian boundary inrerval. Author: defined here . Reference section: Pradalunga secrion, Lombardy Definition: last occurren ce ol ParbabcJolitbu.s robus- Basin (Lozar,1995). tus to the first occurrence of Lr,tthartngìws haffii. Comments: This subzone corresponds to the . Age: late Early Pliensbachian ro Late Pliensbachian. upper part of the NJ 3 Zone of Bown (1982b). The Sine- Reference section: Bosso/Burano secrion, Umbria- murian/Pliensbachian boundary lies in this subzone. Marche Apennines (Faraoni et al., 1996; Mattioli & Morettini, in progress). Comments: This subzone corresponds to the NJT 4 - Similiscutum cruciulus Zone upper part of the NJ 4b Subzone of Bown (1,9871r). B. Author: defined hcre. finchii first appears in the Late Pliensbachian.

PLATE 2

All lighL micrographs crossed nicols, approxin.rately X 3OOO. 1. B. dubiutn, sanple lv{BE 2.}0, Somrna (Centrel Irelv), Early Toarcian; 2. B. grande, sample MBE 2.30, Sornma (Centrel Italy). F,erly Toarcirn; 3. L. barozii, sample NIBE 2.60, Somma (Central Italv), Earil'Toarcian; 4. L. frodoi, sample MBE 2.60, Somn-ra (Centrel Itall'), EerlyToarcirn; 5. L. hauffii, sample MBE 2.J0, Somrna (Central Italy), Early Toarcian; 6. L. hauffi;, sample MBE 2.30, Somrne (CenLrai Ital,v), Early Toxcirn; 7. L. sigíllatus, sanrple FLE 23.25, Fiurninara (Central Italy), Early Aalenran; 8. L. sigillatus, sample MBE 2.60, Somme (Central Itely), Earll' "Ioarcirn; 9. L. crucìcentralis, sample MBE 2.60, Somma (Central ltaly), Earl,vToarcian; 10. L. crucicentralls, sample FLE23.75, Fiuminrtr (Ccnrnl Irrly), Early Aalenian; 71. L. velatus, sample FLE 25.10, Fiuminatr (Central Italy), Early Aelenian; 12. L. oelatus, san-rple FLE 25.10, Fiuminata (Central Italy), Early Aalenian; 13. Calyculus sp. ind., sarnple MBE 2.30, Somma (Central Italy); 14. CalycuLus sp. ind., sample MBE 2.60, Somma (Central Italy); 15. C. superbws, sarnple FLE, 25.10, Fiurninata (Central Italy), Early Aalenian; 16. D. striatus, sample FLE 2J,25, Fiunrinete (CentnI Irrly), Earlv Aalenian; 17. D. ignotus, sample FLE 25.10, Fiuminata (Central Italy), Early Aalenian; 18. D. ignotus, sample MBE 2.30, Somma (Ccntrel Italy), Earll' Toarcian; 79. D. st;atus, sanple FLE 23.75, Fiuminata (Central Italy), Early Aalenian; 2A. D, striatus, sample FLE 25.10, Fiurninata (Central Italy), Early Aalenian. PI.2 Calcareous Nannofossil etents in Lower and Middle ./urdssit 367

1. B. dubium 2. B. granrle 3. L. barozii 4. L.frodoi

5. L. hauffii 6. L. haffii 7. L. sigillatus 8. L. sigillatus

9. L. crucicentralis LO. L. crucicentralis Ll. L. velutus 12. L. velatus

13. Calyculas sp. ind. 14. Calyculu.s sp. ind. f5. C. superbws 16. D. striatus

L7. D. igrntus 18. D. igtuttus 19. D. striatus 20. D. strinîus 368 E. Mattioli & E. Erba

NJT 5 - Lotharingius hauffii Zone NJT 6 - Cailnolithus superbus Zone Author: Bown (1987b). Author: Bown (1982b). Deflnition: first occurrence of Lotharingiws hauffii Definition: first occurrence of Carinolithus superbus to the first occurrence of Carinolithus superbus. to the first occurrence o[ Discorhabdws striatus. Age: Late Pliensbachian to Early Toarcian. Age: Early Toarcian (tenuicostatum to serpentinus Comments: A progressive increase in abundance Zones). and species richness marks the Pliensbachian/Toarcian Comments: This zone is correlative of the NJ 6 boundary. Zone of Bown (1982b). L. wlatus, D. ignotus,.W. colacicchii andW fossacincta first occur in rhis zone. Converse- NJT 5a - Biscutum finchii Subzone ly, some typical representatives of Early Jurassrc assemblages, such as M. jansae, disappear. Calyculus spp. is r Author: defined herc. characteristic constituent of this zone, whereas C. super- Definition: first occurrence of Lotharingius hauffii bws is stlll quite rare. to the first occurrence of Lotharingius sigillatws. ASsociated species: Schizosphaerella spp, Calyculus Age: Late Pliensbachian to earliest Toarcian. spp., B. L. sigillatus, L. crucicentralis, L. ztelatus, Reference section: Pozzale section, Umbria- finchii, L. barozìi, C. crassus, C. caz;ws, M. jansae, B. noaum, B. Marche Apennines (Mattioli, 1995). B. grande, S. lozaei, C. swperbus and D. ignotus. Comments: This subzone corresponds to the NJ finchii, 5a and part of the NJ 5b Subzones of Bown (1,987b). L. umbriensis, L. frodoi, L. barozii, B. prinsii, B. leufwensis and S. lowet. first occur in this subzone. Subzone NJT 5a NJT 7 - Discorhabdus sfrlatus Zone roughly corresponds to the spinatwm ammonite Zone. Author: Bown (198/b). Definition: first occurrence of Discorhabclws striatws NJT 5b - Lotharingius sigillatus Subzone to the first occurrence of Retecapsa incompta. Author: defined here. Age: Early Toarcian (serpentinus Zone) to Late Definition: first occurrence of Lotharingius sigillatus Toarcian (meneghinii Zone). to the first occurrence oî Carinolithus superbus. Comments: This zone first introduced by Bown Range: E,arly Toarci an, tenuicostatwm Zone. (1987b) as D. ignotus Zone, was successively named D. Reference section: Pozzale section, Central Italy striatus Zone in Bown ec al. (1988), who considered D. (Mattioli, 1995). ignotus as a synonim of D. striatus. In this paper some Comments: This subzone corresponds ro the diagnostic characters, allowing the distinction between upper part of the NJ 5b Subzone and the base of the NJ these two species are described, and a different srr.-rti- 6Zone of Bown (1987b) . L. crwcicentralls first appears in graphic distribution is also discussed. In this zone C. the E,arly Toarcian. In this subzone also the first superbws becomes common and D. cricttus , B . depraoatus appearence of the genus Carinolithws is observed, with and T. sulliaanii first occur. C. cantalwppii, M. lenticw- C. cantaluppii and C. powlnabronei. The assemblages laris and small specimens of CaLyculus spp. disappear. become richer and more diversified. Associated species: Schizosphaerella sp., Calyculus Associated species: Schizosphaerella spp., L. hawf- spp., I. haffii, L. sigillatus, L. crucicentralis, L. oelatws, fii, Calycwlus spp.j L. sigillatus, L. crwcicentraLis, L. L. barozii, C. crassus, D. ignc,tus, B. novum, B. finchii, B. crassus, jansae, barozii, C. C. caaus, M. B. novwm, B. grande, C. superbws, D. ignotus, D. striatus,'V/. fossacinc- finchii, B. grand,e, B. prinsii, B. leufwensis and S. lozaei. ttl .

PLATE 3

All light micrographs crossed nicols, approxinately X 3OOO. l. D. criotus, sample FLE 23.75, Fiuminata (Central Italy), Early Aalenian; 2. D. criotus, sample FLE 25.10, Fiurninata (Central Italy), Early Aalen- ian;3. D. criotus, sarctple FLE 25.10, Fiuminara (Central ltaly), Early Aaìenian; 4. R. incompta, sample DB2 130, Digne (South France), Early Brjo- cian; 5. B. depratatus, sample DB2 130, Digne (South Frlnce), Early Bajocian; 6. W colacicchii, sample FLE 25.10, Fiuninate (Central italy), Early Aalenian;7.\It! contracta, sample DB2 130, Digne (SouthFrance), EarlyBajocran; 8. W aff. contrdctd,sample DB2 130, Digne (South France), Early Bajocian; 9. \Y. britanníca, sarnple DB2 130, Digne (South Fmnce), Early Bejocirn; 10. W brìtannica, sample DB2 130, Digne (South France), Early Bajocian; 11.'W. fossacincta, sample FLE 25.10, Fiurninrr.r (Central ltaly), Early Aalenian; 72. \X/. barnesae, sampie ALIL 13, Aulfingen (South Ger- n'rany), Late Oxfordian; 13.'W. nanititae, sample DB2 130, Digne (South France), Early Bajocian; 74. V/. manìvitae, sanplc DB2 130, Drgne (South France), Early Bajocian; 15.'W barnesae, sample AUL 13, Aulfingen (South Germany), Late Oxfordian; 16.W barnesae, sample AUL 13, Aulfin- gcn (South Gerrnany), Late Oxfordian;17. C. margerelll, sample AUL 13, Aulfingen (South Germany), Late Oxfordian; 78. C. tnargerelìi, sample AUL 13, Aulfingen (South Germany), Late Oxfordian; 19. H. magharensls, sample DB2 130, Digne (South France), Early Bajocian; 20. H. rnagbarensis, sample DB2 130, Digne (Sourh France), Early Bajocian. Calcareous NannoJòssiL eoents in Lo..uer and lliddle .lurassìc 369

l. D. criotus 2. D. criotus 3. D. criotus 4. R, incompta

5. B. depravafus 6. W. colacicchii 7. W. contracta 8. W. aff. contracta

9.W. britannica 10. W. britannica ll. W. fossadncta 12. W. barnesae

13. W. manivítae 14. W. manivitae 15, W. barnesae 16. W. barnesae

17. C. margerelii 18. C. margerelii 19. H. mngharensis 24. H. mngharensis E. Mattiolì f: E. Erba

NJT 7a - Discorhabdus sfíafus Subzone Age: Late Toarcian (meneghinii Zone) to Early Author: defined here. Aal,enian (opahnum Zone). Comments: Definition: first occurrence of Discorhabdws striatus this subzone comprises the Toar- cian/ Aal,enian boundary. ìncompta rare to the first occurrence of Discorhabd.us criotus. R. is a quite species and its occurrence is subordinated Age: Middle Toarcian (brtons Tone) to Middle- to the preservation of different lithotypes. L. oelatus and species Late Toarcia n (o ariab ilis -insigne Subzone). belonging to the genus 'Watznaweria become frequent. Reference section: Colle d'Orlando section, Early Jurassic species display limited abundances. Umbria-Marche Apennines (Parisi et al., 1998). Comments: Calyculus spp. becomes rarer, while C, NJT 8b - Watznaueria swperbus and D. ignotus increase in abundance. The contracta Subzone assemblages are occasionally dominated by Biscutaceae. Author: Bown et al. (1988), emended here. 'Watznaueriú Associated species: Schizosphaerella spp., L. crwci- Definitìon: first occurrence of contrac centralis, L. oelatus, L. hawjfii, C. crassus, D. ignotus, B. ta to the first occurrence of Cyclagelosphaera margerelii. no'oLtm, B. finchii, B. grande, D. striatws, C. superbus, W Age: Early Aalenian (opalinwm Zone) to Middle Aalenian (murchisonae Zone). colacicchi i and'W fossacincta. Reference section: Colle d'Orlando secrlon, Umbria-Marche Apennines (Parisi et al., 1998). NJT 7b - Discorhabdus crlofus Subzone Comments: H. magharensls first appears in this Author: defined here. interval. The diversity slightly diminishes wirh respect Definition: first occurrence of Discorhabdus criotus to the previous zone. L. hauffii becomes less abundant, to the first occurrence o{ Retecapsa incompta. D. ignotws and D. striatus are common, and various Ag e : Middle-Late Toarcia n (a ariab ili s -in s ign e Sub - species of the genus V/atznaweria begin to be predomi- zone) to Late Toarcian (menegbinii Zone). nant. This subzone corresponds to rhe upper part of the Reference section: Fiuminata section, Umbria- NJ 8a Subzone and lower part of NJ 8b Subzone of Marche Apennines (Mattioli, 1,994). Bown et al. 11988ì. Comments: the FO ol R, incompta (Late Toarcian) Associated species: Schizosphaerella spp., L. cruci- is recorded in this zone characterrzed by commorrD. centralis, L. velatus, D. ìgnotus, D. striatus, D. criotws,W ignotus and D. striatus. contracta>'W colacicchti, and C, superbws. Associated species: Schizospbaerella spp., L. crwcicentralis, L. aelatws, L. haffii, C. crassws, B. novum, B. NJT 8c - Cyclagelosphaera margerelll Subzone finchii, B. grande, D. striatus, D. ign,otus, W colacicchii and C, swperbws. Author: defined here. Definition: first occurrence of Cyclagelosphaera margerelii to the first occurrence of Watznaueriabrttan- NJT 8 - Retecapsa incompta Zone nLc4, Author: Bown et al. (1988; B. intermedium Zone), Range: Middle Aalenian (murchisonae Zone) to emended here. Name first used for the NJ 8a Subzone of Late Aalenian (concavum Zone). Bown et al. (1988). Reference section: Co1le d'Orlando secrlon, Definition: first occurrence of R. incompta to the Umbria-Marche Apennines a1., .V/atznaueria (Parisi et 1998). first occurrence of britannica. Comments: this zone marks the definitive transi- Age: Late Toarcian (meneghinii Zone) to latest tion to assemblages dominated by Vatznaueriaceae. Aalenian (concaoum Zone). Subzone NJT 8c corresponds ro parr of the NJ 8b Sub- Reference section: Colle d'Orlando secrion, zone of Bown et a1. (198S). Umbria-Marche Apennines (Parisi et al., 1998). Associated species: Schizosphaerella spp., L. aela .Vl. Comments: D. ignotws andD. striatus are common- tus, D. ìgnotus, D. striatus, D. criotus, contracta, '\X/ 1y found. This zone is correlative of the NJ 8 Zone of colacicchii, C. margerelii and C. superbus. Bown et al. (1988). Associated species: Schr.zosphaerella spp., L. cruci- NJT 9 - Watznaueria britannica Zone centralis, L. aelatus, L. haffii, C. crassus, B. noaum, B. Author: Bown et a1. (1988), emended here.-V/atz- finchti, B. grande, D. striatus, D. ignotus, W. colaciccbii and C. superbws. naweria britannica (or synonyrns) was previously used as biozonal marker by Barnard & Hay (1974), Thierstein (1976), Hamilton (1979;1982), Medd (1982) and Bown NJT 8a - Retecapsa incompta Subzone et al. (tlSS). This zone is comparable to the homony- Author: Bown et al. (1988). mous zone of Bown et al. (1988). Definition: first occurrence of Retecapsa incompta Definition: first occurrence of 'Watznaueria britan- .Watznaueria to the first occurrence of contracta. nica to the first occurrence ol'Vlatznaueria manir-titae. Calcareous Nannofossil eztents in Louer and. Middle Jurassic

Age: latest Aalenian (concar.,um Zone) to Early Reference section: Digne :rrea, Soutl-rern France Bajocian (laeoiuscula Zone). (Erba,1990). Reference section: Presale secrion, Umbria-Marche Comments: In this subzone H. magharensls disap- Apennines Baldanza et al., 1990;. pears. This subzone corresponds ro rhe upper part of the Comments: W. britannica can be considered as a NJ 10 Zone and the lower part of the NJ 17 Zone of good marker for the Aalenian/Bajocian boundary. In Bown et al. (1988). The species used for defining Zones 'W. this zone communis,V/atznaueria aÎf . \M contracta and NJ 10 and NJ 11 (Bown et a1., 1988) r..Lre -\Yatznaueria are extremely af[. \Y. maniaitae first occur. The assem- or absenc in Tethyan sections, whereas the markers of blages become completely dominated by species of the Subzone NJT 10b are common both in Tethyan and 'Watznaueria. geilts The correlations between Terhyan Boreal areas and constitures a porenrial tool for correla- and Boreal nannofossil zones become more difficult tions. because of marked provincialism. The species used as zonal markers Boreal domain in the are sporadically NJT 1 1 - Watznaueria barnesae Tone found or virtually absent in the studied sections. Zone Author: defined here. NJT 9 is corretab:rle the upper part of the NJ 8 Zone and Definition: first occurrence of V/atznaueria to the entire NJ 9 Zone of Bown er al. (1988). barnesae to the first occurrence ol CycLtgelosphaera -raiedmannii. Associated species: Schizosphaerella spp., L. ve/a- Age: Bathonian. tus, D. ignotus, D. striatus, D. criotus, \XL contracta,'W -W .W. Reference section: Terminilletto secrion, central c o I a c i c c h i i, C. m arger e lii, britanni c a, c o m m uni s and Appennines (Bartolini et a1., 1995). C. superbus. 'Watznaueria Comments: barnesae is an easily identifiable species and dominares the assemblages. The - NJT 10 Watznaueria manivitae Zone duration of this zone is quite 1ong. Zone NJT 11 is com- Author: Reale et a1. (1991), emended here. parable to mosr of the NJ 11 Zone and NJ 12a Subzone .V/atznaueria Definition: first occurrence of mani-,.,i- of Bown et al. (1988). The lowermosr parr of Zone NJT -Watznaueria tae to the first occurrence of barnesae. 1i is marked by a strong decrease of all rhe species of the Age: late Early Bajocian earliest Bathonian genus Discorhabdus. to .V/. (zigzag Zone). Associated species:'W.. barnesae, contracta,'W Reference section: Terminilletto secrion, central c o la c i c ch i i, C. m arger e /it,'V/. britan n i c a, Vl c o m m un i s and Apennines (Bartolini et al., 1995). W maniaitae. Comments: this zone corresponds to a very long time interval and is calibrated in the examined sections with radiolarian Unitarian Association Zones (Bartolini Discussion. et al., 1995), Zone NJT 10 is correlative of the NJ 10 The proposed biozonation scheme is based on Zone of Bown et al. (1988) Tethyan sections and is aimed ro overcome rhe difficul- Associated species: W contracta, \X/. colacicchii, C. ties in applying to such areas rhe zonal schemes pro- marger e lii,'W. britannica, W comm uni s and W nrania itae. posed for the Boreal domain. The nannofossil events choosen as biomarkers in the Boreal domain are ofren NJT 10a - Watznaueria manivitae Subzone scarce or absent in Tethyan secrions, due to palaeo- Author: defined here. provincialism and to the poor preservarion of several Definition: firsr occurrence of Watznaueria maniai- lithotypes (es. Calcari Diasprigni). tae to the last occurrence of Carinolithus superbus. The resolution of the proposed biozonation is Age: Early Bajocian (laeaiwscwla Zone) to early affected by the nannoplankton evolution in the Jurassic. Late Bajocian (subfwrcatwm Zone). Periods of rapid speciation, such as the Domerian/Toar- Reference section: Drgne area, Southern France cian and Aalenian/Bajocian boundary intervals, akernar- (Erba. lee0). ed with periods of relacive evolurionary srasis, such as Comments: this subzone is comparable to the the Early Pliensbachian and the Bathonian-Kimmerid- lower part of the NJ 1,0 Zone of Bown er al. (1988). gian time intervals. Variable evolutionary rares are therefore responsible for a non uniform biostratigraphic resolution of calcareous nannofossils in the As NJT 10b - Watznaueria communis Subzone Jurassic. illustrated in Figs. 12 and 13, some time intervals display Author: defined here. an extremely high resolution. In the Late Domerian- Definition: lasr occurrence of Carinolithus superbus Early Bajocian interval, several nannofossil zones or to the first occurrence of Watznaweria barnesae. subzones have a duration shorter than one ammonire Range: Lare Bajocian to earliesr Bathonian (zigzag zone, and are shorter than 1 My. On the contrary, in Zone). intervals with low evolutionary rates zones and sub- 372 E. Mattioli G E. Erba

zones are much longer and their duration is of a few mil- domains. It must be noted that the resolution achieved lion years. Despite the low stratigraphic resolution pro- for Ialy/France is very high, similar to that document- vided by nannofossils for the aforementioned intervals, ed for Portugal and much higher than the resolution nannofossil biostratigraphy is still important because obtained in the other areas. The Sinemurian and Bathon- ammonites are scarce or absent and nannofossiis virtu- ian are characterízed by lou. resolution, but very few sec- ally constitute the only biostratigraphic tool available. tions with ammonite control and/ or favourable litholo- The nannofossil scheme here proposed has been gy are available for an improvement of the nannofossil directly calibrated with ammonite biostratigraphy and hi^"t..tì orr.h-t several zonal and subzonal boundaries correspond to \fle highlighted (in bold) the nannofossil events chronostratigraphic boundaries. For example. the reproducible in various areas and allowing inter-regional Dornerian/Toarbian boundary is well defined by the base correlations (Fig. 13). Some events appear to be diachro- of the NJT 5b Subzone; the EarlylMiddle Toarcian nous, but we believe that most discrepancies are biased boundary coincides with the base of the NJT 7a Sub- by different ammonite biostratigraphies apphed in dif- zone; the beginning of the Late Toarcian corresponds to ferent areas. The LOs are in general more diachronous the base of the NJT Zb Subzone; the Toarcian/Aalenian than the FOs, probably due to reworking phenomena boundary lies within the very short NJT 8b Subzone; (and therefore to apparent diachronism) and/or to the the Aalenian/Bajocian is marked by the Watzanueria survival of taxa in particular micro-environments. speciation and is identifiable with the base of the NJT 9 The major differences in type and number of nan- Zone; theEarly /Lare Bajocian boundary corresponds to nofossil events occur in the Bajocian-Bathonian interval. the base of the NJT 10 Zone; the lower and upper In fact, calcareous nannofloras show a very different boundaries of the NJT 11 Zone are correlatable with assemblage composition essentially due to preservatlon. base and top of the Bathonian. In the studied sections, diagenesis-resistant taxa domi- The comparison between the Tethyan nannofossil nate and after the major speciation of the'\X/atznaueria scheme here proposed and the biozonation for the Bore- group at rhe Aalenian/Bajocian boundary, very few al Realm (Bown et al., 1988) shows a high correlability events were detected. In contrast, in the Submediter- (Fig. i2). Therefore, the proposed biostratigraphy rep- ranean Province and in the Boreal Realm better preserved resents a potential tool for correlation among different nannofloras are dominated by delicate forrns sirowing palaeogeographic domains. Moreover, in the Early and high rate of speciation in the Bajocian-Bathonien. Middle Jurassic the stratigraphic resolution of the pro- The present study highlights the importance of posed bioscheme is very high and comparable to other calcareous nannofossil biostratigraphy in the Lower and proposed nannofossil biozonations (Figs. 1,2 and 1,3); Middle Jurassic and shovrs the high resolution achiev- conversely, for the late Middle Jurassic the detail provid- able for intra- and inter-regional correlations. ed by the scheme of Bown et al. (1988) is higher. Acknooledgements.

This synthesis derives from studies carried out for several years. Although the responsìbilitl' of the present biostratigraphy is of Conclusions. the writers, r'e greatly benefrtted of discussions within the Italian Working Group, and in particuler with A. Brl- The biostratigraphic synthesis here proposed for Jurassic Nannofossil danza, M. Cobianchi, A. Fiorentino, S. Gardin, S. Monechi, , F. l-ot- recent the Mediterranean Province is compared to taroli, F. Lozar and C. Pirini Radrizzani. These friends and collesues schemes compiled for Portugai, Morocco and Switzer- are warmly thanked for support and very constructive criticisrn. land (de Kaenel et al., 1.996) and the Boreal Realm Ve wish to extend the warnest thanks to Katharina von Salis (Bown et al., 1988; Bown, 1996) (Figs. 12 and 13). Such and Paul Bown for their extremely helpful reviews. M. Noèl Povedigne of the photographic plates. a comparison is not always easy, due to different rea- is acknowledged for the preparation E. Mattioli was supported by MURST 40% to Guido Parisi end sons: 1) in most papers, range charts displaying relative E.Erba by CNR CT97.00285CT05 to Isabella Premoli Silva. abundances and occurrences of single taxa are often lacking. This prevents an exhaustive comparison of abundances of different taxa and of assemblage compo- RE,FERENCE,S sition between various areas; 2) stratigraphic logs with precise positions of ammonite and nannofossil biohori- AmézieuxJ. - Association de nannofossiles calcaires du zons are often not published; 3) most papers do not 0972) D'Aquitaine et du Bassin Parisien (France). describe the lithologies from which samples have been Jurassique Mém. Bwr. Rech. géol. minier. P'tris., v. 77, pp. 143-151, therefore neither the preservation state nor collected, Paris. the potentiai presence of resedimented beds can be eval- Arkell WS. (1956) - Standard of tirc Europeen Jurassic. Bzl/. uated; 4) a distinct paleoprovincialism in the ammonite Geol. Soc. Am.,v.57, pp. 1-34, Washington D.C. fauna characterizes the entire Jurassic, preventing an Baldanza A., Bucefalo Palliani R. & Mattioli E. (1995) - Lower unequivocal and independent check on the synchroneity Jurassic calcareous nannofossils and dinoflagellate cysts of nannofossil events in different paleogeographic of Hungary and their comparison with assembiages Calcareous Nannofossil ettents in Lou;er and Middle [urassic

frorn Central h.aly. Palaeopelagos, v. 5, pp. 161-174, Bown PR. (1992) - Late Triassic - Early Jurassic CaÌcareous Roma. Nannofossils of tl-re Queen Charlotte Island, Britisl'r Baldanza A., Cresta S. & Mattioli E. (1990) - Bajoci.rn Crl- Columbia. J. Micrctpaleontol., t. 11, pp. 1//-188, Lon- care ous Nannofossils from Monte Nerone Area don. (Urnbro-Marchean Apennine, Italy). Mem. Descr. Carta Bowr-r PR. with contributions from the International Nanno- Geol. d'Italia, v. 40, pp. 225-236, Roma. plankton Association, Jurassic Working Group (1996) - Baldanza A. & Mattioli E. (1992a) - Biostratigraphical synthe- Recent advances in Jurassic caicareous nannofossil sis of nannofossils in the Early Middle of south- Jurassic research. GeoResearch Forurn, v. 1-2, pp. 55-66. ern Tethys. Knihoonicka, ZPN., 11 a., v. 1, pp. 111-141, Bown PR. & Cooper M.K.E. (1989) - New Calcareous Nan- Hodonin. nofossil taxa from tl-re Jurassic. J. Micropaleontol., v. B, Baldanz,a A. & Mattioli E. (1992b) - Biozonazione a Nanno- 9l-90. LonJon. fossili Calcarei deÌ Giurassico Inferiore-Medio della PP. Bown PR. & Cooper M.K.E. (1998) - In PR. Borvn Provincia Mcditerranea (Dominio Tetideo): revisione ed Jurassic. (Ed. C alcar e o us N ann ofo s s íl B t o s trat igraplr7, 3 a- 8 ar-nplian-rento. PaLteopelagos., r'. 2, pp. 69-78, Roma. ) pp. 5, Cambridge. Bernrrd T. & Hay W\( (1971) - OnJurassic coccolitl.rs: A ten- Bown PR., Cooper M.K.E. & Lord A.R. (1988) - A caicareous tati\.e zonation of the Jurassic of Southern England and North France. Ecl. Geol. Heb., v. 67, n. 3, pp. 563-586, nannofossil Biozoriation scheme for the e.rrly to mid Basel. Mesozoic. Neu,tsletter Stratigr., v 20, pp. 91-11.1, Berlin. Bartolini A.,Bigozzi A. 8c MattioliE. (1992) - Analisi strati- Bralower T.J., Monechi S. & Thierstein H. (1989) - Calcareous grafica ed inquadramento sequenziale della porzione Nannofossil Zonation of t1-re Jurassic-Cretaceous giurassica inferiore delia successione di Filettino (M. Lror:ndarv interval ar-rd correlations with the Geon-rag- Simbruini, Appennino centr.ric): un approccio multidis- netic Polarity Timescale. Mar. MicropaL, r,'. 14, pp. 153- ciplinare. Palaeopelagos, v 2, pp. 143-161, Rorna. 235, Amsterdam. Bartolini A., Baumgartner PO. Ec Mattioli E. (1995) - Middle Bucefalo Palliani R. & M:Lttioli E. (1994) - Enrichment in ar-rd Late Jurassic Radiolarian biostratigraphy of the organic matter within the Early Toarcian Marnc di Colle Bertone and Terminilletto secrions (Urnbria- Monte Serrone Formation: a synchronous cvent in the Mrrehc-S;binr Apennines, Cenrr.rl Irrll r: an inregr.rted Umbria-Marche Basin (Central Ita\y). Palaeopelagos, v. stratigraphical approach. In Baumgartner PO. et al. 4, pp. 175-188, Roma. (Eds.) - Middle Jwrassic to Lctroer Cretaceous Radiolaria Bucefalo Palliani & Martioli E. (1998) - High resolution intc- of Tethys: Occwrrences, sìstematics, Biochronolog,, pp. grated microbiostratigraphy of tl-re Lower J.urassic (late S I 7-Rl l, Lau.anne. Pliensbachian-e arly Toarcian) of central Ita,l1,. .1. Baumgartner PO., Martire L., Gorican S., O'Dogherty L., Erba Micropal., v 1/, pp. 153-172, London. E. & Pilìevuit A. (1995) - New Middle and Upper Juras- Cariou E. (1973) - An-inonites of the Callovien and Oxfordi- sic radiolarian assemblages co-occurring with en. In HaÌlam A. (ed.) Atlas of Palaeogeogrdphy, pp. 287 - ammonites and nannofossils from Southern Alps 295. (northern Italy). In Baumgarrner PO. et ai. (Eds.) - Castellarin A. & Vai G.B. (1982) - Guida alla geologia del Micld.le Jurassic to Loruer Cretaceous Radiolaria of Tethys: Sudalpino centro-orienrale. Soc. Geol. It., Guide geo, ()ccurrences. rtstemJttcs. tstochronologt, pp. 737-750, logìche Regionali, 382 pp., Ron.ra. Lausanne. Claps M., Erba E., Masetti D. & Melchiorri F. (1995) - Benedetti L., Bucefalo Paliiani R., Mattioli E., Monaco P, Milankovitch-type cyclcs recorded in Toarcian black Morettini E., Nini C. 8r Nocchi M. (1995) - A muiti- si'rales from the Belluno tough (Southern Alps, Italy). disciplinary approach to L)rganic rrch facies: some exam- Mem. Sc. Geol. Padooa, v.47, pp. 179-188, Padova. ples from Mesozoic and Cenozoic of the Northern Cobianchi M.A. (1990) - Biostratigrafia a nannofossili celcarei Apennines. Europal newsl., n.8, pp. 54-57, Lyon. del passaggio Domeri:Lno-Toarcirno in Val Navezze Bersezio R., Felletti F., Lozar F. & Ruggeri M. (1996) - The (Brescia). Attì Ticinensi Sc. Terrd, v 33, pp. 19-25, Pavia. Concesio Formation of the Lombardian rifted Basin Cobianchi M.A. (1992) - Sinemurian-Early Bajocian Calcarc- (Southern Alps, Italy). Stratigraphy of the Jurassic cal- ous Nannof oss il Bios t rrtigr.rphy of thc Lc.rnbard)' Basin careous turbidite unit. Rio. It. Pal. Strat., v 102, n. 1, pp. (Southern Calcareous Alps; Northern italy). Atti Ticí- 49-64, Milano. nensi Sc. Terra, v.35, pp. 61-106, Pavia. Bombardiere L. (1993) - Analisi se din-rentologica ed ultrastrut- Cobianchi M.A. Erba E. & Pirini-Radrìzzant C. (1992) - Evo- turale del fango carbonatico della Corniola dei massicci iutionary trends of calcareous nannofossil genera Lotha, perugini (Umbria occidentale) e di alcune sezioni del- ringius and Watznaueritr during tl-re Early and Middle l'area umbro-marchigiana. Palaeopelagos, v. 3, pp. 113- Jurassic. Mem. Sc. Geol. Padota, r,r 43, pp. 19-25, Padova. 128, Ron-ra. Colaciccl-ri R. & Bigozzi A. (i995) - Event srratigraphy and Bown PR. (1987a) - The structural development of earll- carbonate platforn-r-basin interrelations during thc Mesozoic coccoliths and its evolutionary and taxonom- Jurassic in the central Apennines. PaLaeopelagos, v 5, pp. ic significance. Abh. Geol. Bunds., v. 39, pp. 33-49, \Xr/ien. 1i 1-128, Roma. Bown PR. (1987b) - Taxonomy, evoÌution, and biostratigraphy Colacicchi R., Nocchi M., Parisi G., Monaco P, Bald:rnza A., of Late Triassic-Early Jurassic calcareous nannofossils. Cresta S. & Pallini G., (1989) - Palaeoenvironmental Palaeont. Ass., Special pap. Palaeont., v. 38, 1 1 8 pp., Lon- analysis from Lias to Maln-r (Corniola to Maiolica For- don. mations) in the Umbro-Marchean basin, Centrel Ir.rl1- 374 E. Mattioli €. E. Erba

(preliLnin.rry reporr). 2nd Intern. Symp. on Jurassic Jàger M., Oschmann \M & Seiiacher A. (Coordinators) (1995) Strat., v. II, pp.716-728, Lisboa. - III EPA Vorkshop "Black Shales Models", 26 pp, Dot- Cresta S., Cecca F., Santantonio M., Pallini G., Brònnimann P, ternhausen. Baldanza A., Colacicchi R., Monaco P, Nocchi M. & de Kaenel E. E< Bergen J. A. (1993) - Ncw Early and Middle Parisi G. (1989) - Stratigraphic correlations in theJuras- Jurassic coccolitl-r taxa and b.iostratigraphy from the sic of the Umbria-Marche Apennines (Central Iraly). eastern proto-Atiantic (Morocco, Portugal and DSDp 2nd Internat. Symp. onJurassíc Strat., v. II, pp. 729-744, Site 547 B). Ecl. Geol. Helo., v 86, pp. 861-90/, Basel. Lisboa. de Kaenel E., Bergen J. A. & vor.r Salis Perch Nielsen K. (1996) Crux J. A. (1984) - Biostratigraphy of Early Jurassic Calcare- - Jurassic caÌcareous nannofossil biostratigraphv of western Europe. Compilation ous Nannofossils from sourhwest Germany. N. Jb. of recent studies and cal- Geol- Palàont. Abh.,v. 169, n.2, pp. 160-186, Stuttgart. ibration of bioevents. BuÌ\. Soc. Géol. France, r. J.67, pp. 1 5-28, Paris. Crux J. A. (1987) - EarlyJurassic calcareous nannofossil bios- Hallam A. (1969) Faunal Realms tratigraphic evenrs. Nevtsl. Stratigr., v. 17, pp. 79-1,A0, - and facies in the Jurassic. Palaeontol., v. 1.2, pp. 1-1 B, London. Berl i n. Hamilton G. B. (1977) - EarÌy caicareous Dale B. (1983) - Dinoflagellate resting cysts: benrhic plankton. Jurassic nannofossils from Portugal and their biostratigraphic use. Ecl. Geol. In Frixell G. A. (Ed.) Survival strategies of the Algae. Helr,., v. 70, pp. 575-597, Basel. Univ. Press, pp. 69-136, Carrbridge. Hamiìton G. B. (1979) - Lower and Middle Jurassic calcareous Deflandre G. & Fert C. (1954) - Observations sur les coccol- nannofossils from PortugaL EcÌ. Geol. Heh;., v. 72, pp. ithophoridés acruels et fossiles en microscopie ordinaire 1-18, Basel. et éÌectronique. Ann. Paléont., v. 40, pp. 115-176, Paris. Hamilton G. B. (1982) - Triassic and Jurassic calcareous nan- Erba E. (1990) Calcareous nannofossil biostratigraphy - of nofossils. In Lord A. (Ed.) A stratigraphical index of some Bajocian sections from the Digne area (SE calcareous nannofossils, pp. 136-137, British Micropale- France). Descr. Mem. Carta Geol. d'Italia,v. 4A, pp.237- ontological So ciety, Chicl-res ter. 256, Rorna. Flenriques M. H., Gardin S., Soares A. F., Gomes C. R., Rocha Erba E. & Cobianchi M. A. (1989) - Upper Carixian to Lower R. 8., Marques J. F., Lapa M. R. & Montenegro J. D. Bajocian nannobiohorizons identified in the Lombardy (1994) - The Aalenian-Bajocian boundary at Cabo basin, in Clari PA., Cobianchi M.A., Erba E., Gaetani Mondego (Portugal). In: Cresta S. and Pavra G. (Eds.), M., Martire L. and Pavia G. (Eds.). Escursione sul Proceed. of the 3rd Intern. Meeting on Aalenian and Giurassico delle Alpi Meridionali, Mìlano. Bajocien. Stratigraphy, MisceLlanea Sero. Gectl. Naz., v. 5, Faraoni P, Marini A., Pailini G. & Venturi F. (1996) - New pp. 63-78, Rorna. Carixìan ammonite assemblages of Centrai Apennines Loza"r F. (1992) - Biostratigraf ia a Nannof ossili calcarei nel Lias: risultati (Italy), and their impact on Mediterranean Jurassic di alcune sezioni nel Bacino Lombardo e nel biostrarigraphy. Palaeopelagos, v 6, pp. 75-122,Roma. Bacino Delfinese. Palaeopelagos, v. 2, pp. 89-98, Roma. Farinacci A., Mariotti N., Nicosia U., Pallini G. & Schiavinot- Lozar F. (1995) - Calcareous nannofossil biostratigraphy of Lower Liassic from \lestern Tethys. to F. (1981) - Jurassic sediments in the Umbro- Palaeontogr. Italica, v. 82, pp. 91.-1.21., Marchean Apennines: an alternative model. In.: Farinac- Pisa. Martini E. (1971) - Standard Tertiary and cale are- ci A. and Elmi S. (Eds.) Proceedings of tbe Rosso Quaternary ous nannoplankton zonation. In: Proceed.ing of the 2nd Ammonitico Symposiun, Roma, pp. 335-398, Roma. Plankt. Conf, Rome (Ed. A. Farinacci), 2, pp.739-785, Gaetani M. (1975) - Jurassic srratigraphy of the Southern Alps. Roma. In: C. Squyer (Ed.) - Geology of ltaly, The Earth Science MattioÌi E. (1993) - Quantitative anaiysis of calcareous nanno- Society ofthe Líbyan Arab Republic, pp.377-4A2, Tripoli. fossils in the Liassic portion of Pozzale secrion (Martani Gaetani M. 8c Erba E. (1990) - Il Bacino Lombardo: un si- Mts., Central Italy): preliminary reporr. Palaeopelagos, v. stema paleoaÌto/fossa in margine un continentale passi- 3, pp.261-278, Roma. vo durante il Giurassico. Gwida alle Escursioni 75" Con- Mattioli E. (1994) - Calcareous nanr.rofossil contenr of rhe gresso Nazionale Soc. Geol. It., Escurs. A3, Milano. Toarcian-Aalenian Fiuminara secrion (Ccntral Apen- Gordon \( A. (1970) - Biogeography of the Jurassic forami- nines, Italy). Palaeopelagos, v.4, pp. 175-188, Roma. nifera. Geol. Soc. of America B ull., v. 81, pp. 1689- 1 704, Mattioli E. (1995) - Late Liassic calcareous nannofossiis from New York. the Pozzale secrion (Martani Mts., Centrai Italy): a A.., Goy Ureta S., Arias C., Canales M. L., GarciaJoral F., Her- quanr ir"rtive appro.rclr ru cvrluàrc productivity and di.r- rero C., Martines G. & Perilli N. (1994) - The Fuentel- genesis. Acta Congresct Nanoplancton, pp. 83-103, Sala- saz section (Iberian range, Spain), a possible srratorype manca. for the base of the Aalenian srage. In: Cresta S. and Mattioli E. (1996) - New calcareous nannofossil species from Pavia G. (Eds.), Proceed. of the 3rd Intern. Meeting on the Early Jurassic of Tethys. Rirt. It. Paleont. Strat., v. Aalenian and Bajocian Stratigraphy, Miscellanea Sera. 102, pp. 397-412, Milano. Geol. Naz., v 5, pp 1-31, Roma. Mattioli E. (1997) - Nannoplankton productivity and diagene- Gradstein F. M., Agterberg F. P, Ogg J. G., Hardenbol J. van sis in the rhythmically bedded Toarcian-Aalenian Fiu- Veen Il ThierryJ. 8r Huang Z. (1994) - A Mesozoic time minata section (Umbria-Marche Apennine, centraL scale, /. Geophys. Àes., v. 99, pp. 24,A51-24,074, lVash- Italy). Palaoegeogr., Palaeoclim., PalaeoecoL, v. 130, pp. ington D.C. 11.3-1.33, Amsterdam. C,zlcareous Nannofossil eoents in Lower and. Middle Jurassìr 375

Medd A. W (1921) - Some Middle and UpperJurassic Coccol- growth and demise l-ristory of a carbonate plrtforn-r. ithoplroridae from England and Frrnce. Proc. II Plank- Mem. Sc. Geol. Padota, v '18, pp. 171.219, Padova. tonic Conf., Roma., v.2, pp. 821-844, Roma. Pittet B. & Strasser A. (1998) - Depositional sequences in Medd A. \úl (1982) - Nannofossil zonation of the English Mid- deep-shelf environrnenrs formed through carbonate- dle and Upper Jurassic. Mar. Micropaleontol., v. 7, pp. mud import frorn the shallow platform (Late Oxfor- 23-95, Amsterdam. dian, Gerrnan Sw-abian Alb and eàsrern Swiss Jura). Ecl. Morettini E. (1999) - Lower Juressic Stable Isotope Stratigra- Geol. Heht., v 91, pp. 149-169, Basel. phy (Carbon, Oxygen, Nitrogen) of the Mediterranean Prins B. (1969) - Evolution .rnd srretigraphy of Coccolithinids Tethys (Central Italy and Southern Spain). Unpublished from the Lower and Middle Lras. Proceedings First Inter, Ph. D. thesis, Univ de Lausanne, 88 pp. national Conference on Planletonic Microfossils, v 2, pp. Moshkovitz S. & Ehrlich A,. (1976) - Distribution of Middle 547 -558, Genève. and Upper Jr-rrassic calcereous Nannofossils in the Reale V, Baldanza A., Monechi S. & Mattioli E. (1992) - Ca.\- northeastern Negev, Israel, and Gebel Maghara, north- careous Nannofossil L.iostratigrapl-ric events from the ern Sinai. Israel Geological Suraey Bullettin, v. 69, pp. 1- Early-Middle Jurassic sequences of the Urnbria-Marche 48, Israei. area (Central laly). Metn. Sc. Geol. Padota., v 43, pp. Moshkovitz S. & El'rrlich A. (1981) - Late Jurassic Calcareous 41-75, Padova. Nannofossils in Israel's offshore and or-rland Areas. Reale V & Monechi S. (1994) - Cyclagelosphaera wiedmannii

I sra e I G e o lct gic a I S uru ey B ull e ttin, v. 7 4, pp. 65 -7 2, Is r ael. new species, a marker for tl-rc Callovia.n..fourn. of Nan- Moshkovitz S. & Ehrlich A. (1987) -'\Xlatznaweria maniaitae nctf. Res., v 16, pp. 117-119, Kyjov Bukry: taxonomic problerns and distribution in the Reinhardt P (1965) - Neue Farailien fùr fossile Kalkflagellaten Jurassic Cretaceous sediments of Israel and other (Coccolithophoriden, Coccolitl-rinecr-r) aus dem Meso- Tethyan areas. I.N.A. NerosÌetters, v 9, pp.110-115, Lon- zoikun-r Deuschlands. Mor-ratsber. Deutsch. Akad. V/eis- don, sensch. Berlin, v 7, pp. 30,40, Berlin. Nini C., Baldanza A. Ec Nocchi M. (1995) - Late Domerian- Riding J. B. (1984) - A palyr-rological investigation of Toarcian Toarciar-r calcareous nannofossil biostratigraphy, benth- and earlv Aaienian strara from thc Blea .ù/yke area, ic foran-riniferai assemblages rnd their paleoenviron- Revenscar, North Yorkshire. Proceedings Yorksbire Geo- rr-rentai implications. Montebibico area (Spoleto, Cen- logical Society, v. 46, pp. 231-266,Leeds. tral italy). Reaue de Paléobiologie, v. 14, pp. 271-319, Rood A. P & Barnard T. 0974) - On Jr-rrassic coccolrths:

Genève . Stepbanolithion, Dìacloz,ygus and related generà. Ecl. Norris G. (1965) - Provincialisn'r of Callovian-Neocomian Geol. Helo., v 65, pp. 327-342,Basel. dinof lagellate cysts in the Northern and Southern Sciunnach D. & Erba E. (1991) '- Il "selcifero" di Lingornctt., Hemisphaeres. In.: Am. Assoc. Strat. Palynol. (Contr. (Canton Ticino). Boll Soc. Tic. Sc. Nat., v.82, pp. 65- Ser. 4), pp. 29-35, Dallas. 110, Lugano. Stoico Baldanza O'Dogherty L., Baumgartner P O., Sandoval J., Martìn-Algar- M. & A. (1995) - Early and Middle Jurassic ra A. & Piilevuit A. (1995) - MiddÌe and UpperJurassic calcareous nannofossil biozonation of the Monti Sabini radiolarian a'sernblagcs uo-occurrinB with ammonites area (Latiun-r, Northcrn Apennine-central Italy). from tl-re Subbetic Reahn (Southern Spain). In Beum- Palaeopelagos, v. 5, pp. 75-110. Roma. Stradner H. (1963) - New contributions ro Mesozoic srrarrg- garten P O. et. al. (Eds.) - Middle Jurassic to Lower Cre- taceous Radiolaria of Tethys; Occwrrences, sistematics, rapl-ry by means of n.rnnofossils. froc. 6th Voild Petr. Congr. Sect. Paper 1,67-184, ar.r.r B i ot hronctlog. pp. 7 17 -7 24. L.rusanne. 1 I, pp. Frankfurt - - Olrmert !(1 & Rolf C. (1994) - The Aalenian boundaries at ]Vla1n. Vittnau (Oberrhein area, south-west Germany). In: Thierstein H. R. (1976) - Mesozoic caicareous nannoplankton Cresta S. and Pavia G. (eds.), Proceed. of the 3rd Intern. biostratigr.rphy of marine sediments. Mar. Micropaleon- Meeting on Aalenian and Bajocian Stratigraph;r, Miscel- tologt. u. l. pp. 325-3r'2. Am.tertlarn. lanea Seru. Geol. Naz., v. 5, pp. 32-62, Roma. Vòròs A. (1977) - Provincialitv of the Mediterranean Lower Parisi G., Baldanza A., Benedetti L., Mattioli E., Venturi F. & Jurassic brachiopod fauna: causes and plate-tectonic implications. Palaeogeogr. v. Cresta S. (i998) - Toarcian strrtigraphy of the Colle PalaeocLimatol. Palaeoecol., 21, pp. 1-16, Amsterdam. d'Orlando section (Umbria, Central Ital;1 Northern Vòròs A. (1979) - Pliensbachian bracl-riopods biogcogrepl.ry of Apennine). Bc.,ll. Soc. Paleont. (t.,y.37, pp. 3-39, Modena. tlre "Mediterranean rlicro-continenr". Actd Geol. Perch Nielsen K. (1985) - Mesozoic Calcareous Nannofossils. Hung., v.30, pp. 59-80, Budapest. In Bolli H. M., Saunders B., Perch Nielsen K. (Eds): J. Wiegand G. E. (1984) - Tivo Ncrv Genera of Calcarcous Nan- "Plankton Stratigraphy". Cambridge Unittersity Press, nofossils fron-r the Lowcr Jurassic. J. Paler,,ntol., v 58, Cambridge. pp. 1151-1155, Tu1sa. Pettinelli R., (.1997). Nocchi M. & Parisi G. Late Pliensbachi- \Winterer E. L. & Bosellini A. (1981) - Subsidcnce and sedi- an-Toarcian biostratigraphy and environmental inter- mentation orr J ur.rrsic p.rssiv. conr irrcrrrrl nr.rrgirr. pretations in the Ionian Basin (Lefkas, Island) as coln- Southern Alps, Italy. Bull. Am. Petr. Geol., v. 65, pp. pared to the Umbria-Marchean Basin (Ccntral ltaly). 394-421, Boulder. Boll. Sera. Geol. Ital.,v. 11, pp.9/-158, Roma. Young J. R., Teale T. & Bown P R. (i986) - Revision of the Picotti V & Cobianchi M. (1996) - Jurassic periplatforrn Stratigraphy of the Lor-rgobucco group (Liassic, south- sequences of the eastern Lombardian Basin (Southern ern Italy), based on new data from nannofossils and Alps): the deep-sea record of the tectonic evoiution, ammonires. E-, l. Crcl. Helu.. t.7q, pp I l7- ll5. B;,e1. 376 E. Mattioli & E. Erba

Appendix 1 Genus Mitrolithzs (Deflandre, 1954) Bown Er Young, 1986 Mitrolithus jansae (Viegand, 1984) Bown & Young in Young et al., Index of cited species 1986

Mitrolithws elegans D efland,re, 79 54 Gems Biscwturn Black in Black Er Barnes, 1959 Mitrolithus lenticularis Bown, 1982b Biscutum depraratus (Grùn 8t Zweili, 1980) Bown, 1987b Biscutwn dubium (NoéL, 1965) Grùn in Grùn et a,l., I974 Genrs Par h ab d olith u s D efltndr e, 19 52 Biscutum finchii (Crux, 1984) Bown, 1982 Parhabdolithus liasicus Deflandre, 1952 Biscutum grande Bown, 1987b Parhab clolithus rob ustus Noèl, 1 965 Biscwtum novwn (Goy,1979) Bown, 198/b Genns Retecapsa Bll.ck, 1971, Gents Bussonius Goy, 1979 Retecapsa incompta Bown & Cooper, 1989 Bussonìus prinsll (Noel, 1973) Go1r, )979 Bussonius leufuensis Bown 8c Kielbowicz, 1987 in Bown, 1987b Genus Similiscutum deKaenel & Bergen, 1993 Similiscutum aùtwm de Kaencl & Berr:en, 1993 Genvs Calyculur NoèI, 1973 Símilìscutum cruciubts de Kaenel & Berecn, 1993 Calyculus sp. indet. Similiscutum orbiculus de Kaenel & Bergen, 1993

Genus Carinolithus (Prins in Grùn et il., 1,974) Bown, 1982b Genus So//aslres Black, 1967 Carinolithus canta/uppii Cobianchi, 1990 Sollasites louei (Btkry, 1969) Rood er il.,1971 Carinolithus poulnabronei Matrìoli, 1996 Carinolithus superbus (Deflandre, 1954) Prins in Grùn et aL, 1974 Genus Triscutum Dockerill, 1982 Triscutum sulliranii De Krenel tr Bergen, 1993 Gents Crepidolithus Noè|, 1965 Crepídolithus carus Rood, Hay Ec Barnard, 1973 Gents Tubirhabdus Prins cx Rood, Hay & Barnard, 1923 Crepidolitbus crassus (Defla,ndre, 1954) NoéI, 1965 Tub irhab dus p at ulus Fteinhx dr, 19 65 Crepidolithus grdnulatus Bown, 198/b

Genus V/atzndueria Prernh:-rdt 1.) 6 4 Cenrs Cyclagelosphaera Noèl 1965 V/atznaueria barnesae (Black in BÌach & Bernes,1959) Perch-Nielsen, Cyclagelospbaera margerelii Noé1, 1965 1968 CyclageÌospbaera uiedmannii Reale & Monechi, 1994 Watzna u eria b ritannic a (Stradner, 1 9 63) Rernhardt, 1 964 'V/atznaueria colaciccbii Mattioli, 1996 Genrs Discorhabdus 1965 Noé| Watznaueria comm unis Reinhardt, 1 96,1 Discorhabdus cricttus Bown, 7987b 'V/atznaueria contracta (Bon'n & Coop.r, t9S9) Cobrenchi, Erba e Discorhabdus ìgnotus (Gorka,, 1957) Perch-Nielsen, 1968 Pirini Radnzzani, 1992 'Watznaueria Díscorhabdus striatws Moshkovitz Ec Ehrlich 1926 tff.'W. contracta F,rba, 1990 'Watz-naueriafossacincta (Black, 1971) Bown in Bos'n & Cooper, 1989 Genus Lotharinaias 1973 ernend. 1979 '\Yatznaueria NoèÌ, Goy, maninitae Bukry', 1 923 'Watznaueria Lotharingius barozii Noè1, 1973 zfÍ.'V/. maniritae Cobianchi, Erbe & Pirini Rrdrizz-.rni, Lotbaringiws uucicentralis (Medd, 19l1) Grùn 8r Zwetli, 198A 1992 I-otharingius umbriensis Mattioli, 1996 I-otharingius frodol Martioli, 1996 INCEK_IAE SEDIS Lotbaringius hauffii Grún & Zweili in Grùn et a1.,7974 Lotharingius sigíllatus (Stradneq 1961) Prins in Grùn et a|.,1.974 Genus Hexalithas Gardet, 1955 Lotharingius relatks Bown & Cooper, 1989 Hexalithws magharensìs Moshkovitz & Ehrlich, 1926

Genus Mazaganella Bown, 1987b Genus S chizo spbaerella D efltndre & I)angeard, 1 93 8 Mazaganella puila Borvn, 1982b Schizosphaerella pultctkldtd Dcflandre & Dangeard, 1938