MANZANILLA Formation. Pliocene – Upper Miocene
(Trinidad, B. W. I.).
Author of name: WARING (G.A.) (1926). The geology of the Island of Trinidad B. W. I. The John Hopkins Univ., studies in Geology no 7, p. 59
Type locality Manzanilla Bay, east coast of Trinidad.
Thickness About 4500 feet in onshore Trinidad. It extends from the Venezuelan border in the Gulp of Paria to at least Block 3a on the east coast of Trinidad.
References: WALL (G.P.) & SAWKINS (J.G.) (1860); GUPPY (R.J. L.) (1866b); MAURY (C. J.) (l925a); MANSFIELD (W. C.) (1925); WARING (G. A.), (1926); RENZ (H. H.) (1942); RENZ (H. H.) (1948).
The Manzanilla Formation has been subdivided into four Members according to Kugler:
The Telemaque Sand Member
The Montserrat Glauconitic Sandstone
The San Jose Calcareous Silt
The Los Atajos Silt and Conglomerate.
From a biostratigraphic standpoint the Manzanilla s.l. is typified by the presence of Textularia 22, Anomalina 4 and Uvigerina 3 with associated Rotalia/Elphidium.
The upper and lower boundaries tend to be strong unconformities . in the Gulf of Paria the Telemaque Member rests with angular unconformity on the so called pre-Manzanilla surface.
In this case it may rest on Nariva , Brasso or Tamana .
The San Jose Calcareous Silt
It has been described as an inky blue unctuous calcareous claystone, in outcrop there are occasional conglomerates with clasts of northern range metamorphics. To date it has not been identified in any well in the Gulf of Paria.
Montserrat Glauconitic Sandstone
A bivalve and Gastropod rich sandstone with glauconite pellets. In outcrop this unit ranges from about 10′ – 300′. It is absent in the Gulf of Paria.
It can be subdivided into two units a lower unit with thick sands and minor lignites and an upper unit containing thin coarsening upward sands and thicker lignites. Telemaque faunas are typified by floods of Miliolid 6 with levels of Rotalia and Elphidium.
In the Gulf of Paria between the Warm Springs and North Marine Master Fault, thin limestones are found in the lower part of the Telemaque. These limestones are, white – grey, moderately hard – hard, micro crystalline, very argillaceous, dense, silty or conglomeratic, white, black, spotty, massive, medium – coarse grained, well consolidated, generally homogeneous, sample consists of limestone fragments, silts and lignites. Sands are sand clear , loose very fine grained, sub rounded – sub angular, light grey, very fine grained- fine, friable, moderately – poorly consolidated, very calcareous – non calcareous, carbonaceous – glauconitic, pyrite, loose fossils. Porosity ranges from 17.6 – 26%. Claystones are dark grey – grey, firm – very firm-moderately hard, blocky moderately fissile, non – moderately silty, slight – non carbonaceous, slightly calcareous. Lignite black hard, dense, blocky shiny, anthracitic lustre. anhydrite, cream, white, hard, granular, pyritic. Fossil fragments highly fragmented unrecognizable, pearly lustre, bivalves
South of the North Marine Master Fault to the Los Bajos Fault ,sands from west to east are are very fine grained, silty, dirty with shale inclusions, non calcareous, porosity ranges from 31.3% -36.1%, perms 350 – 1550md, abundant glauconite and reworked Nariva fauna are present. firm – soft, very fine grained, with shale & lignite inclusions, non calcareous, accessories muscovite and carbonaceous material , porosity ranges from 24.8 -35.9, perms 37 – 1480md. Shale – silty, non calcareous, olive grey, rare muscovite and forams (Gallai & Archie 2015)
S. Gazalie, C. Lakhan and C. Archie, 2016, Recent Advances in the Understanding of Northern Basin Stratigraphy, Gulf of Paria: Integrating Biostratigraphic and Palynological Analysis, AAPG 2016 International Conference and Exhibition