52 



UNITED STATES NATIONAI, MUSEUM BULLETIN 215 



in the same section we find two small outcrops of the 

 highly calcareous Guayaguayare formation (transition 

 Globotruncana gansseri — Ahathom'phalus mayaroensis 

 zone). The contact with the Naparima Hill formation 

 is, however, not exposed. 



Because of the virtual absence of surface sections it is 

 fortunate that a number of subsurface profiles are 

 available, thus permitting the study of a fairly con- 

 tinuous sequence of Upper Cretaceous foraminiferal 

 faunas. 



For reasons abeady mentioned, and because of the 

 possibility of correlation with established type sections 

 in Europe and North Africa, where the same forms are 

 found, species of Praeglobotruncana, Rotalipora, Globo- 

 truncana and Abathomphalus have been chosen for the 

 zoning. Several species that prove to be important 

 markers in Europe and North Africa have not yet been 

 recorded in Trinidad. Rotalipora cushmani (Morrow), 

 R. reicheli Mornod, R. turonica Brotzen, and Praeglo- 

 botruncana stephani (Gandolfi) constitute one group of 

 species absent so far from known Trinidad sections. 

 They are restricted to the upper part of the Ceno- 

 manian. A widespread hiatus between the Gautier 

 and Naparima Hill formations, with the Upper Ceno- 

 manian and probably the lower Turonian missing, 

 may thus be assumed. Globotruncana calcarata Cush- 

 man, which is probably restricted to the upper part of 

 the Campanian, is another form not yet recorded in 

 Trinidad, suggesting that a minor stratigraphic gap is 

 likely to exist between Naparima HUl formation and 

 Guayaguayare formation. This is further supported 

 by an abrupt change in lithology between the two 

 formations. 



Because the distribution of the various zones in 

 Trinidad is so irregular, it is quite possible that the 

 missing intervals are present but have not yet been 

 found. 



The Gautier formation consists of dark grey to black, 

 noncalcareous or calcareous shales. Strongly indura- 

 ted shales, sandstones and conglomerates may be 

 iaterbedded. Based on faunistic evidence, the age is 

 considered to be Albian to lower part of the Cenoma- 

 nian. The formation is divided into the following 

 zones (from top to bottom): 



Rotalipora appenninica appenninica zone 

 Globigerina washitensis zone 

 Rotalipora ticinensis ticinensis zone 



The Rotalipora ticinensis ticinensis and Globigerina 

 washitensis zones have both been established in the 

 subsxirface section of Trinidad Leaseholds well Marac 1 

 (coordinates N:152141 links, E:424447 Hnks). The 

 type locality for the youngest zone is located in the 

 Gautier Eiver (right side branch of Cunapo River at 

 junction of waterfaU branch, north of Chert HUl, lYi 

 miles southeast of Mamon Guaico-Tamana Road, 

 eastern Central Range, coordinates N: 33 1460 links, 

 E: 526400 links). Some of the samples collected there 

 consist of up to 9 percent by weight of Foraminifera, 

 predominantly Globorotaliidae and Planomalininae. 



The maximum recorded thickness of the Gautier for- 

 mation is about 2,000 feet. 



The Naparima Hill formation consists in its upper 

 part of argillite, a whitish to grey-brown siliceous in- 

 durated claystone with an average CaCOa content of 

 10 to 20 percent. Towards its base, the formation 

 becomes increasingly weU-bedded and shaly, with occa- 

 sional interbedded sands; the colour then changes to 

 dark grey or black. Based on megafossU and micro- 

 fossU evidence, the Naparima Hill formation ranges 

 from Turonian to Campanian. The following zones 

 are distiaguished (from top to bottom): 



Globotruncana stuarti zone 

 Globotruncana fornicata zone 

 Globotruncana concavata zone 

 Globotruncana renzi zone 

 Globotruncana inornata zone 



The bottom four zones had to be established in sub- 

 surface sections. In the Globotruncana inornata zone 

 (Trinidad Petroleum Development well Moruga 15, 

 coordinates N: 149878 links, E:497002 links) are foimd 

 the single-keeled Globotruncana inornata, new species, 

 G. schneegansi Sigal, and G. helvetica BoUi, with no 

 double-keeled species. The Globotruncana renzi zone 

 (Trinidad Petroleum Development well Moruga 15, 

 coordinates N: 149878 links, E:497002 links) is defined 

 by the first occurrence of double-keeled Globotruncana 

 {Globotruncana renzi Gandolfi and G. cf. lapparenti 

 coronata Bolli) and the absence of Globotruncana con- 

 cavata (Brotzen), G. vnlsoni, new species, and G. forni- 

 cata Plummer. Restricted to the Globotruncana con- 

 cavata zone (Trinidad Leaseholds well Marac 1, co- 

 ordinates N:151141 links, E:424447 links) are the 

 zonal marker and Globotruncana wilsoni, new species. 

 The Globotruncana fornicata zone (Trinidad Petroleum 

 Development well Moruga 15, coordinates N:149878 

 links, E:497002 links) is characterized by the absence 

 of Globotruncana concavata (Brotzen) and G. stuarti 

 (de Lapparent) in an assemblage that contains Globo- 

 truncana fornicata Plummer. 



As in the case of the Gautier formation, only the 

 highest zone is known from the surface. Its type 

 locality is the Naparima Hill in San Fernando (Usine 

 Ste. Madeleine Quarry at the SE end of the hill; coordi- 

 nates N:235800 links, E:364000 links). The zonal 

 marker Globotruncana stuarti (de Lapparent) appears 

 first in the upper part of the Naparima Hill forma- 

 tion, and continues into the Guayaguayare formation. 

 The relatively scarce Globotruncana ventricosa White 

 and Praeglobotruncana coarctata, new species, are con- 

 fined to the Globotruncana stuarti zone. The maximum 

 recorded thickness of the Naparima Hill formation is 

 about 2,000 feet. 



The Guayaguayare formation, consisting of blotchy, 

 grey, highly calcareous shale, overlies the Naparima 

 Hill formation. The major part of the formation is 

 regarded as Maestrichtian, though its lower portion 

 is of possible late Campanian age. Outcropping iso- 

 lated slipmasses of the Guayaguayare formation have 

 been discussed and described previously (Bolli, 1950, 



