STUDIA GEOLOGI CA POLONICA Vol. 114, Krak6w 1999, pp. 35-75. Mesozoic stratigraphy of Cuba Edited by A. Pszczolkowski Andrzej PSZCZOL• KOWSKI 1 & Ryszard MYCZYNSKI' I Nannoconid assemblages in Upper Hauterivian-Lower Aptian limestones of Cuba: their correlation with ammonites and some planktonic foraminifers2 (Figs 1- 13, Tabs 1- 3) Abstract. The nannoconids are abundant in the Lower Cretaceous pelagic limestones in western and central Cuba. In some lin1estone beds, these nannofossils occur together with ammonites or planktonic foraminifers. Our samples were collected from the Polier, Veloz and Paraiso formations. The Late Hauterivian to Early Aptian age of the studied samples is based mainly on ammonites. The nannoconids identified in these samples are grouped in 4 assemblages: Late Hauterivian, Early Barremian, Late Barremian and late Early Aptian. In the Early Barremian assemblage, the narrow­ canal nannoconids are by far more frequent than the wide-canal ones. Small specimens, classified herein provisionally as N truittii truittii, occur also in this assemblage. On the other hand, the representatives of the Nannoconus steinmannii group are absent in the late Early Aptian assemblage, which includes the wide canal forms only. Nannoconids found in one sample may represent an assemblage of the earliest Aptian age. Key words: Nannoconid assemblages, ammonites, planktonic foraminifers, Lower Cretaceous, western and central Cuba. INTRODUCTION Pelagic limestones are the most important lithologic components of the Creta­ ceous passive continental margin and basinal successions in Cuba. These fine­ grained limestones often lack identifiable macrofauna, while stratigraphically use­ ful microfossils are scarce or absent, especially in the Hauterivian to Aptian carbon­ ate rocks. The Lower Cretaceous pelagic limestones of Cuba are strongly lithified and tectonized. Coccoliths are infrequent and/or poorly preserved in these rocks, the dissolution-resistant species being the most common taxa. The nannoconids are Institute of Geological Sciences, Polish Academy of Sciences, ul. Twarda 51/55, 00-818 Warszawa, Poland. 2 Manuscript accepted for publication September 21, 1999. 36 A. PSZCZOLKOWSKI & R. MYCZYNSKI usually less affected by carbonate dissolution and diagenesis being the principal source ofbiostratigraphic information for many pelagic limestone beds (nannomic­ rites ofErba & Quadrio, 1987). Although the coccoliths are frequent in marls and marly limestones (Busson & Noel, 1991), such rocks are uncommon in the Early Cretaceous successions of Cuba. Systematic affinity ofnannoconids is uncertain. Busson and Noel (1991 ) com­ pared these nannofossils with calcareous dinoflagellates. In Cuba, the Bema­ sian- Valanginian nannoconid assemblages are dated by calpionellids (Bronni­ mann, 1955), while the Hauterivian, Barremian and Aptian nannoconid assem­ blages can be correlated, sometimes, with ammonites. Planktonic foraminifers are scarce in the Valanginian-Barremian limestones (see Pszcz6ikowski, 1999), but do occur in some Lower Aptian limestones. The main objective of our paper is to date the Late Hauterivian to Early Aptian nannoconid assemblages in Cuba by the ammonites and the planktonic foramini­ fers. A stratigraphic standard of the Late Hauterivian- Early Aptian nannoconid as­ semblages is proposed, based on this correlation. In the present paper, the calcare­ ous nannofossils (mainly nannoconids) and the planktonic foraminifers have been studied by A. Pszcz6lkowski, and the ammonites have been identified by R. Myc­ zynski. PREVIOUS WORK Since the pioneer work by Bronnimann (1955) the stratigraphic distribution of nannoconids in Cuba was not studied in detail. Bronnimann (1955) described sev­ eral new species of the genus Nannoconus Kamptner, 1931 and tentatively deter­ mined the stratigraphic distribution of nannoconids in central Cuba (former Las Villas Province). There, he recognized three typical assemblages ofnannoconids: (1) Nannoconus steinmanni - N. aff. globulus - N colomi, associated with calpi­ onellids; (2) N. steinmanni - N. colomi- N kamptneri - N. bermudezi - N. globulus (with rare "globigerinas" in a single section); and (3) N. truitti - N. minutus - N. elon­ gatus - N bucheri - N. wassalli, associated with Orbitolina sp. The age of the as­ semblage 1 was determined as the Neocomian, of the assemblage 2 as the Barre­ mian, and of the assemblage 3 as Aptian to Albian (Bronnimann, 1 955). These tentative age correlations have not been verified or improved until re­ cently (see Pszcz6lkowski, 1999). A single information on the occurrence of Nan­ noconus cf. truittii Bronnimann and Nannoconus cf. minutus Bronnimann deter­ mined by Dr A. de la Torre in the limestones ofthe Polier Formation at Nottey (Casa Blanca) was presented in Myczynski and Triff (1986). Outside Cuba, the Early Cretaceous nannoconid stratigraphy was the topic of several studies (e.g., Trejo, 1960; Moshkovitz, 1972; Deres & Acheriteguy, 1980; Erba, 1989). Trejo ( 1960) distinguished six nannoconid zones (A-F) based mainly on data from Nmthem and Eastern Mexico; these zones were correlated with mi­ crofossils and ammonites. Deres and Acheriteguy (1980) established 11 nannoco­ nid biozones in the latest Jurassic through Cretaceous (pre-Maastrichtian); in this NANNOCONID ASSEMBLAGES OF CUBA 37 '~ATANZAS' ~ CO~ i MARTf •""' 1 6""'• •a ~ 5 ) - ~.. J ;VILLA 'AATANZAS C LARA 1f_l!.OV PROVINCE _,..· ' _ _ t·" 1 J ( ( ~ "-. CJE NFUEG OS ' 0 60 KM Fig. l. Location map showing sites sampled in western and central Cuba (see inset for location of the studied area in Cuba). Sampled sites (triangles): 1-Nortey (Casa Blanca); 2a- Lorna Caldoso; 2b - South of Bahia Honda (and Quinones); 3-Mango Bonito hill; 4 - Lomas de Polier; 5- El Sordo Viejo; 6 - Silverio-Cabrera hill; 7- La Sierra; 8 - South of Playa Gamuza; CORR. - Corralillo time span, they described and figured thirty seven species and subspecies of the ge­ nus Nannoconus,and defined the age of their assemblages by applying the first and the last occurrences of particular species as stage boundaries (see Perch-Nielsen, 1985). Erba (1989) correlated nannoconid events with calcareous nannofossil, cal­ pionellid and planktonic foraminiferal biostratigraphy in Northern and Central Italy. The Early Cretaceous ammonites were studied in the Pinar del Rio province (Fig. 1) and in the area near the border of the Matanzas and Villa Clara provinces (Myczynski, 1977; Myczyflski & Triff, 1986). The Berriasian- Hauterivian ammo­ nites of Cuba, Mexico and southern United States belong to the same zoogeo­ graphic province. On the contrary, the rich Barremian ammonite assemblage of Cuba is similar to the coeval European one (Myczyflski, 1994). SAMPLES AND METHODS The samples were collected in 1970- 1990 during our field work ( 1970- 1990) in the Pinar del Rio, Matanzas and Villa Clara provinces of Cuba (Fig. 1). The lime­ stone samples in the Pinar del Rio province (Tab. -1) belong mainly to the Polier For­ mation (Berriasian-Aptian). In central Cuba, three samples were collected from the Veloz Formation (Tithonian- Aptian) and one from the Paraiso Formation (Hau­ terivian- Aptian?), close to the border between the Matanzas and Villa Clara prov­ inces (Fig. 1; Tab. 1). Fresh cuts of limestone were studied in the SEM. These cuts were taken from 1 1limestone samples containing the ammonites figured in this pa­ per and (in one case) in an earlier publication (Myczynski & Triff, 1986). In one sample, the age ofthe nannoconid assemblage was established based on planktonic foraminifers identified in thin sections. 38 A. PSZCZOLKOWSKJ & R. MYCZYNSKJ REGIONAL SETTING OF STUDIED SAMPLES The limestones of the Polier Formation (Pszcz6lkowski, 1978) were sampled at five sites in the northeastern part of the Pinar del Rio province: Nortey (Casa Blanca); Lorna Caldoso; south ofBahi a Honda (and Quinones); Mango Bonito hill; and Lomas de Polier (Fig. 1; Tab. 1). Four samples were collected from limestones ofth e Paraiso and Veloz formations in sites located in the Matanzas and Villa Clara provinces, central Cuba (Fig. 1; Tab. 1). Table 1 Geographic location of samples used in this study rc -·- - ·- I- ·- --·--------·----··---------· rSa~ _ _ l__ Forma ti o~-t- ------ Location_. __ -----: M-87/3 ~ ., ' 1 l' 1 ~ - 8 8112- p 0 Nortey (CasaBlanca) locality, northeast of San Cristobal, AM- S/l ~r- _linar del Rio province m western Cuba (sit~ Fi g.~- 1 ~ 8 4 --4-__ I p !' /Lorna Caldoso, south of Bahia Honda (and Quinones), ~- I -H 0 ~ ~ ----2 ~ ___I er __ ~a r del R~rovincc in weste.r_!!_Cub ~~ i teE_in ~i& Jj_ -j ·jAM-8512 Polier I~~ut ? of Balna Honda (and Qmil.on~s) , Pmar del R10 I ----+-- ____ ~ovmce, western Cu~ stte_1!)_!Q f't!L,l)_ - ··---...j ~M - 90125 Polier I~-an go. Bo~ito hill, Pinar del Rio province in western Cuba I 1_:__+------t~ 3m F 1 g.~) . ·- -:---:-- - · ._J ~6P - 598 __ ~-- ~o li e~ _ ~~:;~~l:her, Pmar del Rw provmce, western Cuba (stte I AM-9411 Veloz IEl Sordo Viejo. locality si~atc? southeast of Marti, --j ·---- ~---·-- . _ Matan~rovmce ~j_m F.!&, l.l _____ ._ ._ / AM-93/23 1 Silverio-Cabrera hill located near the border of the 1 -·--- ~ Veloz jMatanzas and Villa Clara provinces in central Cuba (site 6 I A~ M-93/28 in Fig. l) _M_ _ :-r--Velo-z- - --,L -a-S~ie"""rra..._l_o_ca-li-~-,-n car the b.ord-er_o_f the. -M-at-~n-za-.s - an-d - -~ 3 23 f ---· ·- _______ Vtlla C l a~rovm ces m central~uba__0J t e 7 m F!&)l.___ [ r . ISouth of P.laya Gamuza, east of Corralillo, northwestern II !AM-95_:__j_ _ Para1:__ ~~~;.~~the Villa Clara province in central Cuba (s it~ l.:_j Nortey (CasaBlanca) section The limestones of the upper part of the Polier Formation, exposed in the Nortey (Casa Blanca) section (Fig. 2: A) located in the eastern part of the Pinar del Rio province, yielded many Early Barremian ammonites (Housa & de Ia Nuez, 1975; Myczyilski, 1977). Later findings of ammonites by Myczynski and Triff (1986) suggested a Barremian- ? Aptian age of these limestones. The limestones in ques­ tion are about 6 m thick (Fig. 2: A). NANNOCOl-110 ASSEMBLAGES OF CUBA 39 c Sections: D A - Nortey (Ca•• Blan ca ) B -Lema Caldoso C - Man9o Bonilo D -Lomas de Polier 1-­ A ...: Prote tragon:te-s sp.