62 



TUSriTED STATES NATIONAL MtTSEtJM BULLETIN 215 



normal stratigraphic succession in the 1,200 feet of 

 Lizard Springs penetrated in the well. The thickness 

 of the zones varies in this well from approximately 

 100 feet to 500 feet. 



The distribution chart (text-fig. 11) of the species of 

 Glohigerina and Globorotalia clearly shows the short 

 ranges of most species within this age period. This 

 short range pattern led to the present subdivision 

 of the Lizard Springs formation into eight zones 

 based on the stratigraphic distribution of character- 

 istic single species or groups of species. The arenaceous 

 facies is placed in a separate zonule. Five lower zones 

 and the zonule are included in the lower Lizard Springs 

 and regarded as Paleocene; the remaining three zones 

 comprise the upper Lizard Springs, and are placed in 

 the lower Eocene. 



The lower Lizard Springs-upper Lizard Springs 

 boundary is marked by a distinct change in both 

 planktonic and benthonic Foraminifera. Two plank- 

 tonic species become extinct in the top zone of the 

 lower Lizard Springs and eight appear new in the 

 bottom zone of the upper Lizard Springs. Only one 

 Globorotalia species {G. aequo, Cushman and Renz) 

 ranges from the lower into the upper Lizard Springs. 

 In addition, numerous benthonic forms such as the 

 Upper Cretaceous-Paleocene Rzehakina epigona (Rze- 

 hak) , Clavulina aspera var. whitei (Cushman and Jarvis) , 

 Gaudryma pyramidata Cushman, Trochammina ruth- 

 ven-murrayi Cushman and Renz and Bolivinoides 

 trinitatensis Cushman and Jarvis are not known from 

 the upper Lizard Springs formation. 



The complete change of the planktonic foraminiferal 

 faima between the Upper Cretaceous Guayaguayare 

 formation and the Paleocene-lower Eocene Lizard 

 Springs formation is not followed by the benthonic 

 Foraminifera. According to recent investigations by 

 J. P. Beckmann (private commimication) as many as 

 about two-thirds of the benthonic species known in the 

 Upper Cretaceous continue into the Paleocene-lower 

 Eocene. In cases where only benthonic Foraminifera 

 are present, it may become difficult, therefore, to 

 determine whether a fauna is of Upper Cretaceous or 

 Paleocene age. Some of the earher students on 

 foraminiferal faimas of the Lizard Springs formation 

 restricted their observations mainly to the benthonic 

 part. Their preference for attributing an Upper 

 Cretaceous age to the Lizard Springs formation is thus 

 well imderstandable. 



The distribution of the zones and zonule in surface 

 and well sections of central and south Trinidad is very 

 irregular. In the Central Range area the arenaceous 

 facies is known as Chaudiere formation, and is strongly 

 predomiuant as such. Towards the south, calcareous 

 benthonic and planktonic Foraminifera become pre- 

 dominant and the arenaceous facies often remains 

 restricted to the basal part of the formation. 



The zones of the Lizard Springs formation as specified 

 in this paper may not yet represent a continuous strati- 

 graphic sequence. There are indications of at least 

 two stratigraphic breaks; these will be considered in 



the discussion on coifing. It is stUl possible that such 

 missing intervals are present in certain areas but have 

 not yet been found. 



The Lizard Springs formation consists of grey or 

 green-grey, calcareous or noncalcareous shales. The 

 greenish color appears to be restricted to the lower 

 Lizard Springs. The calciima carbonate content in the 

 calcareous facies varies from 5 to 30 percent. The 

 percentage by weight of Foraminifera at the type 

 localities varies from 1 to 6 percent. 



Lower Lizard Springs Formation 



The lower Lizard Springs formation is divided into 

 the following zones and zonule (from bottom to top): 



Rzehakina epigona Zonule 



Type locality: Trinidad Petroleum Development 

 weU Moruga 15, Trinidad (coordinates N:149878 Hnks; 

 E:497b02 links), core 4,617-37 feet. 



Remarks: The zonule consists entirely of an are- 

 naceous fauna and is found restricted to the basal part 

 of the formation in many subsurface sections of south 

 Trinidad. It may, in addition, represent a facies 

 equivalent to any of the lower Lizard Springs zones. 

 Rzehakina epigona (Rzehak) becomes extinct at the 

 top of the Globorotalia velascoensis zone. It is a typical 

 form throughout the Chaudiere formation of the Central 

 Range. Thus it may be assumed that this formation 

 is an age equivalent of the whole, or part, of the lower 

 Lizard Springs. The Rzehakina epigona zonule is 

 known to rest unconformably on the Upper Cretaceous 

 in several places. The contact is often marked by the 

 St. Joseph boulder bed (BoUi, 1952). In some parts of 

 south Trinidad however, sedimentation appears to be 

 uninterrupted between the Upper Cretaceous Guay- 

 aguayare formation and the Paleocene Lizard Springs 

 formation. There, the Rzehakina epigona zonule can 

 possibly replace parts of the Guayaguayare formation 

 and thus represent also an Upper Cretaceous age. 



Globorotalia trinidadensis Zone 



Type locality: Trinidad Petroleum Development 

 well Moruga 3, Trinidad (coordinates N:143522 links; 

 E:504382 finks), core 10,259-61 feet. 



Remarks: The Globorotalia trinidadensis zone is 

 characterized by the first appearance of calcareous 

 benthonic and planktonic Foraminifera. The plank- 

 tonic fauna with Globorotalia compressa (Plummer), 

 G. pseudobulloides (Plummer), G. trinidadensis Bolfi, 

 new species, Globigerina triloculinoides Plummer and 

 G. daubjergensis Bronnimann shows strong aflBnities 

 to that described from Danian localities of Denmark 

 (Bronnimann, 1952), to the basal part of the Esna shale 

 (Buffer zone) of Egypt (Nakkady, 1951) and to parts 

 of the Midway (e. g., Plummer, 1926). 



The species of Globigerina and Globorotalia of the 

 Globorotalia trinidadensis zone originate either in this 

 zone or in a favorable facies environment contempo- 

 raneous with the underlying Rzehakina epigona zonule. 



