11ACTIVITIES
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ACTIVITIES |
1. REPORT ON SURVEY OF THE FRENCH RESEARCH VESSEL
'LE SUROIT'
C. Roberts (Ministry of Energy)
IFREMER (Institut Francais de Recherches pour l'Exploitation de la Mer), in conjunction with the Institut de Geologie
du Bassin D'Aquitaine with Mr. George Vemette as head of the mission, conducted a scientific expedition within
the Caribbean during the period 19th October to the 2nd November, 1987, in an area between latitude 10.300N and 12.00N,
and longitude 58.00W and 6O.300W. The mission was divided into 3 main areas (fig 5).
(1) Offshore Barbados
(2) Orinoco
(3) El Pilar
The last 2 areas are within waters under the sovereignty and/or jurisdiction of Trinidad and Tobago. High resolution
seismic and sub-bottom profiling were run in all areas, along with cores, with both still and video pictures. The
main purpose of the mission was to study tectono-sedimentary phenomena on active shelf banks. This was broken down
into 3 areas:
(a) to define the morphology of diapiric formations, their geometry, and the sedimentary fades of the basins, within
the accretionary prism.
(b) to estimate the tectonic impact on the morphology and sedimentation processes during the Quaternary period.
the age and composition of the material ejected due to diapirism; and the contribution of gravity-associated
sediments,
(c) to identify the source of the sediments.
Apart from the 6 French scientists on board. representatives from the Venezuelan Ministry of Energy and the
Trinidad and Tobago Ministry of Energy were also present.
AREA I - OFFSHORE BARBADOS
GEOPIIYSICS: The parameters for running the seismic survey remained constant for the entire trip and were as follows:
(1) The boat speed remained constant at between 10 to 11 knots
(2) The water gun was automatically discharged every 10 seconds.
(3) The range of the signal was 20 to 220 Hz, the filter used had a bandwidth of 26 to 170 Hz.
(4) Imaging occurred every 5 seconds with a total sweep every 5 seconds.
(5) The pre-amplification was 40 db.
(6) The gain was between 20 and 35db.
(7) The hydrophone array consisted of a cable 100 m long, with a spacing of 30 cm between each hydrophone for the
first 50 m, and a spacing of 40 cm between each hydrophone for the next 50 m. There were 4 groups of hydrophones.
CORES: Ten 9 m "Kullenberg" cores were taken in this area. Out of the 10 cores, 5 recovered less than
5 m. In general, the cores recovered were basic-ally the same. The top meter consisted of a light red brown clayey
sand, the grains were quartzitic in composition and very well rounded. Also present were shell fragments, which
were difficult to identify. Progressing further towards the bottom of the :ore, the colour changed to a light
grey with the clay content increasing.
Anomalies were found in cores 4 and 6:
Core 4 Only 2 m of the core were retrieved. This core differed from the others, in that there was a greater sand
content. On board discussions attributed this to the fact that it might be part of a turbidity sequence.
Core 6 - This core had interbands of grey clay and brown sand. suggesting either a flux in the source of the sediment
supply or a rise and fall of the sea level.
AREA II ORINOCO
GEOPHYSICS: The parameters for the high resolution seismic remained the same. An interesting feature was noticed
on the sub bottom profiler. which was not as noticeable on the seismic. At l00 33.77' N, 570 46.37' W at a water
depth of approximately 3.635 m, a structure with the appearance of a deep river canyon was noted. It was approximately
110m wide and 74m deep and in cross section had the appearance of a mature river channel with levees on both banks.
Several of the smaller V-shaped channel features were noted. An analogy would be the main course of a river with
its tributaries as it crosses a delta viewed in cross section. Also noted were the presence of several high seamounts,
the tallest being approximately 1900 m high
CORES: The cores in this area were similar to those taken in the Barbados area. However, the clay content was much
higher. The colour changed from a light grey to a greenish grey with streaks of blue. The water content in the
clays decreased progressively down the core and the clay became more compact. An abundance of foraminifera of the
species Globorotalia and Globigerina, with some Amphistegina, were present, as well as radiolaria and small
coral polyps.
CAMERA: During the viewing of the camera run in a water depth of 2,000 m the major feature noted was the presence
of ripple marks in bands, probably akin to some sort of channel flow. These ripple marks indicate the presence
of underwater currents in a 2900 direction. Abundant dark concretions as opposed to the lighter types found
in the Barbados area, were present between these apparent channels of ripple marks. The area around them
showed minimum amount of deposition of sediment. Also. on top of some of the larger accretions were striations
in a roughly NW-SE direction. probably indicating scouring action. These accretions may be interpreted as:
(a) Remnants of a lava flow or rock outcrops.
(b ) Mineral deposits, or
c) Hydrocarbon seepage that have solidified on contact with water.
Also seen were the remnants of possible mud volcanoes volcanic craters. These vents appear to have had less sediment
deposited within the crater. but several showed erosion on the south side of the vent possibly due to high energy
bottom currents.
AREA Ill EL PILAR
GEOPHYSICS: Seismic along with the sub-bottom profiler were run in this area. Seismic was not run along the Tobago
shelf area because the water was too shallow , which would result in too much noise being recorded. The sub-bottom
profiler showed that there were at least two other levels of the coral reef platform, which had been submerged
during the last sea level rise Also evidence for some recent faulting was noted.
From this area the ship started on its journey towards Venezuela along the North Coast. This route was a modification
of the initial route which would have passed through the Serpent's Mouth. The modification was necessary since
the draft of the boat was more than the 20 m water depth in that area.
CORES: The description of these cores were the same as for those taken in the Orinoco area. The clay colour was
a bit darker in comparison, and there was also a large number of foraminifera. Three of the 7 cores taken did not
retrieve any samples. It was thought that the seafloor was probably a lot firmer than expected in this area, and
as result the corer may not have been weighted enough.
CAMERA: The two camera runs showed basically the same type of sea bottom fauna and structure. Some deep sea specimens
of coral. such as Porites porites, were present in this area, as well as some bivalves.
Ocean Drilling Program (ODP) Workshop, focusing on Caribbean Problems and Scientific Drilling Initiatives was held
in Jamaica 17 to 22 November 1987.
The aim of this conference and workshop was to generate a package of projects which would convince ODP's management
to devote a significant portion of the project's efforts to this area. A tentative target of 6 - 7 legs was proposed.
About 60 geologists attended the meeting, which was subdivided into 3 sections: a Conference which began on Wednesday
17th November. and went on until the following day at about 3.00 p.m.; a Workshop which lasted for a day and a
half; and a half day Plenary session before closing.
THE CONFERENCE: The chairman of the meeting, R. Speed, began by outlining the meeting's objectives. He explained
that the ship would only become available when it had completed its current schedule, which ends in 1992. The duration
of the ship's visit to the Caribbean was dependent on how convincing a list of projects this workshop prepared
for presentation to ODP's management.
R. Buffier explained how the ODP's management worked, especially how funds were disbursed and the committee system
responsible for deciding on the ship's priorities. Some time was spent discussing the mechanical and safety constraints
of the drill ship, as well as time and cost estimates.
W. Hay then reviewed the history of the ODP and the Deep Sea Drilling Project (DSDP). He reviewed the holes which
had been drilled in the Caribbean and lamented over the poor recoveries in those early wells. However, he
explained that technological advances now promise higher recovery rates and more data could be collected
at each hole with new downhole devices. He recounted experiences in the Cariaco Trough to emphasise the hazards
of drilling through hydrocarbons.
The introductory talks were followed by presentations intended to update participants on the latest concepts
in Caribbean geology. These presentations were subdivided into 4 topics as follows:
(I) The tectonic evolution of plates and oceanic lithosphere.
(2) Palaeoceanography sediment history geochemistry.
(3) Active margin and accretionary tectonics.
(4) Magmatic processes including magmatic arcs and ophiolites.
The presentations outlined specific problems or concepts which could be resolved by data generated by the ODP drill
ship.
THE WORKSHOP: After almost 2 days of presentations participants were assigned to 4 panels, each devoted to one
of the conference topics. Participants were reminded that all formal recommendations should have a thematic rather
than a regional flavour since thematic projects are currently more fashionable and therefore more likely to be
successful.
I was invited to sit on Panel 2: Palaeooceanography sediment history geochemistry which was chaired by J. Saunders.
We decided on the theme 'Paleogateways and Cretaceous to Recent oceanography in the Caribbean." Because
the Caribbean had a unique oceanographic setting, as the sluice-gate for circulation between the two big oceans
from Jurassic to Recent times, it was decided that the entire sedimentary section had to be recovered, preferably
at two sites. Furthermore, our group recommended that piston cores should be taken in the Venezuelan, Colombian
and Yucatan Basins to gather data on Miocene to Recent circulation.
POSTER SESSIONS: Some of the more interesting poster sessions are highlighted.
(a) J. Pindell, who has developed an interesting evolutionary model for the Caribbean;
(b) K. Burke, who showed the results of his interpretation of the Trinidad north coast deep (and shallow?) water
seismic. He seems to be proposing an east-west wrench fault south of Trinidad
(c) A. Mascle et al., who are planning to publish a new map of the Caribbean which may be printed by the AAPG;
(d) R. Speed, who is doggedly insisting that relative plate motions are changing, causing under thrusting of
the Guiana Shield under the Northern Ranges, thereby creating a Southern Basin foreland thrust belt;
(e) A preview of a new geological map of Martinique.
The PLENARY SESSION: This session was brought forward to the evening of the 20th. The synthesis of each panel's
thematic proposals was presented under the following headings:
(1) Paleogateways;
(2) Plate margins and the Cayman Trough;
(3) Magmatism in the Island Arc;
(4) Sea floor plateaus;
(5 ) Forearc basins and accretionary process;
(6) Fluid migration in the forearc;
(7) Cretaceous to Recent oceanography in the Caribbean.
A heated debate began when it was contested that the inclusion of too many forearc items on the shopping list
would somehow reduce the Caribbean project's impact because forearcs had ready received attention in recent drilling.
As no solution was forthcoming the Chairman proposed an extraordinary meeting of the Panel chairmen to arrive
at a more acceptable list, which would subsequently be forwarded to all participants
3. REPORT ON THE USGS GEOPHYSICAL SURVEY
L. Phillip (Ministry of Energy,)
N. Lewis (1nstiuite of Marine affairs)
P. Beard (Ministry of Food Production, Marine Exploitation, Forestry
and the Environment)
Discovery of the earth's spheroidal shape has been attributed to observed differences in the curvature of the meridian
as a function of latitude. Local variations in the gravity field affect the curvature at particular latitude. Though
a detailed model of the earth's gravity field has been obtained from satellite data, studies on a local basis are
necessary for updates. This survey, part If an ongoing effort by the Defense 4apping Agency ~MA) of the United
States of America to add to the existing
ill the unsurveyed gaps of this region ~t will also help to improve the overall 'picture of the regional geology.
The United States Geological Survey (USGS) through the United States Embassy, requested approval from the Government
of Trinidad and 'Tobago to conduct this marine geophysical survey within its territorial waters. The request was
approved with he recommendation that 3 scientists, representatives from various institutions, be allowed to accompany
the
research team aboard the 'R/V Starella".
The 'RV Starella" departed from Chaguaramas on December 3rd. 1987 at 4.00 p.m. to begin the gravity and magnetic
survey. The initial part of the survey was conducted off the north coast of Trinidad. The survey re-commenced
in the Gulf of Paria on December 8th, 1987 and ended on December 13th, 1987. This survey covered the north and
east coasts, the Columbus Channel and the Gulf of Paria.
Initially, the USGS had planned to collect approximately 1853 kin (1000 nautical miles) of data east and north
of Trinidad. These proposed survey lines. approximately 9.2 km (5 nautical miles) apart were oriented east to west.
The tie-lines had an orientation of north to south except around Tobago where the orientation was northeast to
southwest on either side of the island.
After consideration of the proposed USGS program and consultation with the oil companies the Ministry of Energy
requested the extension. Westwards, of the survey lines off the north coast of Trinidad and also of Tobago in order
to obtain data in areas where gravity surveys were never conducted. The Ministry also suggested the inclusion
of an east to west survey line in the south coast and several in the Gulf of Paria. Gravity data along these additional
lines, it was thought would help in the delineation of major structures such as the Los Bajos Fault and the El
Pilar Fault.
One objective of geophysical surveys is the application of various techniques for the location of economic resources.
Although the USGS main aim is to add to the world data bank and improve the existing spheroid, the acquired gravity
data can be utilized to fulfill this objective to a significant extent. Gravity exploration detects subsurface
structures and stratigraphic features by the effect they produce at the surface of the earth's gravitational field.
This method is best utilized wherever formations have densities significantly different from the surrounding material.
Gravity data allow the interpreter to establish fault locations, basin shape and extent structural trends and prospect
leads. They are used mainly as a reconnaissance tool in the early stages of exploration, but can be of considerable
importance in the later phases.
Magnetic surveys (measurement of the earth's magnetic field or its vertical component over areas of interest)
are usually employed for the location of concentrations of magnetic material, or for determining the depth to the
basement.
Recording of magnetic data during this survey ended on December 5th, 1987 due to a malfunction of the magnetometer.
However, during its deployment data were obtained continuously and the processed data were stored in 10-second
increments. The limited data acquired were also processed by USGS systems and formatted according to the DMA format.
Bathymetric data, which are of utmost importance to the maritime agencies, will provide a model of the seabed's
shape in the archipelagic waters, the territorial seas and areas of the Exclusive Economic Zone of Trinidad and
Tobago. Such a model should have a significant input into the planning schemes of these various agencies.
The parameters formulated and used in this particular survey were not designed for geophysical exploration but
for the improvement of the ~ 0 Id geodetic spheroid. An average grid spacing of 9.2 km may be too large for
the interpretation of smaller anomalies (Structures) associated with hydrocarbons. However, major structures
such as the Los Bajos and the El Pilar faults should be interpreted utilizing this data. The acquired gravity data
should present a better overall picture of the variations of the regional gravity. Further to this, Bouguer
and residual maps can be made to complete our interpretations.
The acquired gravity data , after corrections are made, will be added to the existing gravity map of Trinidad and
Tobago to infill the existing gaps. The USGS has promised to supply the corrected data.
Similar data acquired in Venezuelan waters will be of great importance for Trinidad and Tobago with regards to
a geological interpretation. Since this survey is for the public domain, every attempt should be made to acquire
the data in Venezuelan waters as soon as possible.
4. COMPUTER MAPPING?
P. Vilain (TRINTOC)
There has been a lot of talk and activity recently in some of our companies about 'Computer Mapping'. Perhaps
it would be useful to expand a little on what computer mapping is all about and what has in fact been taking place
recently.
It has been possible to use computers to draw maps for the last 20 years. As with any thing else, the software
to achieve this has improved considerably over the years and continues to improve at an astonishing pace. Concurrent
with this is the ever increasing power of computers, particularly the micros and smaller minis, and continuous
improvement in their price performance ratios.
Computer mapping today is far more involved than just the drawing of maps. Typical capabilities of a small 2-user
system with a cost of about US $100,000.00 would include the following:
- the preparation of base maps showing cultural data (roads, rivers, coastlines, lease boundaries), wells, well
information, well tracks, engineering data, production data and accurate shot point base maps from the original
navigation tapes;
the preparation of contour maps (both structural and isopach) with the necessary treatment of faults;
- detailed volumetric and reserves calculations;
- the timing of hand interpreted paper seismic sections and the automatic posting of the times on the shot point
base map;
- preparation of cross sections which include the well logs;
- preparation of fence diagrams;
- preparation of isometric (3D) displays of structures;
- conversion of map projections.
Having the capability to carry out the above in-house has a number of
advantages. If the company's well data is available within a corporate well database, the data retrieved in a search
can be passed to the mapping system for the rapid preparation of a base map or contour map, for example. Also,
in addition to maps drawn on a marker or for a particular formation, other types of maps could include sand/shale
ratio maps, production maps, iso-porosity maps, iso-facies maps and isopach maps of any type. Where a well database
is not available, data can be input manually via the keyboard and/or a digitiser.
Computer prepared maps can be stored on the computer and updated rapidly as new information or interpretations
become available, almost like an 'electronic map rack'. These stored maps can be reproduced at any scale or any
projection. Existing manually contoured maps can be digitised and quickly reproduced unchanged or at different
scales and projections, then rapidly updated as new information (e.g. a new well) becomes available. Thus map maintenance
becomes very quick and far less costly.
If a reservoir simulation is to be undertaken, for example, and the geology/reservoir data has been mapped
on the computer, then the grid cell data can be passed to the simulator. The reservoir engineer is thereby saved
that very tedious and involved step.
The benefits described above can probably best be summarized as making the geologists, geophysicists and engineers
more efficient and cost effective. Where mapping systems are not available and in particular, where well databases
are also not available, a tremendous amount of time is spent gathering, plotting and otherwise arranging data
before any contouring, interpretation or analysis can begin.
Apart from people having to do less tedious, mechanical work, their data preparation time is reduced resulting
in
More time being available for interpretation, hence improving interpretation quality.
Today's mapping programs are typically menu-driven and very user-friendly. As such detailed specialist knowledge
beyond the initial training on the system is not necessary to use the large majority of the features these packages
offer. Therefore one envisages geologists, engineers, technical assistants and draftsmen using the system.
Now all this probably sounds as though the days of the geologist are numbered but this is certainly not so. It
is very important to appreciate very early on that these mapping packages are only tools which will do some of
our 'mechanical' data preparation and organisation work for us. However, the user unfortunately must carefully
guide the system, following thought processes hardly different from those followed in the traditional manual
mapping process.
A logical enhancement to a computer mapping package is the acquisition of a seismic interpretation package
which brings the image of the seismic line up onto the screen. This allows the interpreter to do his work on the
screen rather than with coloured pencils on paper prints of the sections, and to automatically transfer the interpretations
to maps.
This is usually referred to as a seismic interpretation workstation and is not to be confused with computer mapping
packages.
With regards what has been happening recently within our companies: Trintoc and Trintopec have decided to
acquire computer mapping packages this year. To this end, 3 software companies were short-listed and have just
completed demonstrating their products in Trinidad. Technical recommendations for a purchase of one of these should
be known soon. Other companies - (Ministry of Energy, Trinmar, NEC, Water Resources and the Institute of Marine
Affairs) attended the demonstrations and have all expressed their serious interest in acquiring systems of
their own.
5. TRINTOPEC 1988 SEISMIC SURVEYS
V. Young On (TRINTOPEC)
TRINTOPEC has undertaken 2 seismic surveys for 1988 (Fig. 6). One, a marine survey in their offshore South Marine lease consisting of 850 km of high resolution
and deep penetration seismic coverage. The other, a portable dynamite land survey in their newly allocated leases
in Maloney and Quinam/Mome Diablo, consisting of 61 km and 83 km of coverage respectively.
The marine survey was contracted to Western Geophysical Co., U.S.A. and conducted by their survey ship "R/V
Western Anchorage". The survey commenced on February 18, 1988 and concluded on March 16, 1988. The vessel
was subsequently released to Amoco Trinidad Oil Co. to acquire several high resolution exploration wellsite surveys.
The land survey was also contracted to Western Geophysical. The survey commenced on February 26, 1988 in the Maloney
area and was completed on April 23, 1988. The survey is continuing in the Quinam/Morne Diablo area and the expected
completion date is May 28, 1988. The data are recorded on 120 channels with 60-fold multiplicity. A portable dynamite
source consisting of a 1 lb explosive charge in 3 m deep shot-holes at 25 m intervals is being used for the land
survey.
Both surveys are part of TRINTOPEC's ongoing exploration program and are expected to cost the company approximately
$10.5 million (TT) this year.
In December, 1987 the Minister of Energy, Labour, Employment and Manpower Resources offered, by way of a Competitive
Bidding Order, 3 submarine blocks for Exploration and Production licences. Tenders were invited from local and
foreign companies by direct communication and through advertisements in daily newspapers and trade journals. This
is the first of 3 bid rounds scheduled up to 1990. Mr. Anthony Paul, Acting Director of Geology and Geophysics
at the Ministry of Energy, was interviewed on the overall success of this round of bidding and his comments are
summarised here.
Eighteen companies paid a fee of US$25,000 to be eligible to bid for any or all of the blocks (Table 1). This entitled them to a data package to help evaluate the
potential of the blocks. Five bids were received for Block S-l1 off the South Coast of Trinidad and 2 for the Block
Lower Reserve L off the South East Coast (Table 2).
No bids were received for the U-shaped Block. The blocks and those identified for future bid rounds are shown in
Figure 7.
At the time of writing, the bids have been evaluated by a technical team of experts from the Ministry of Energy
and other governmental agencies and the Minister is expected to make an announcement on the winners at any moment.
Besides the 18 companies that were eligible to bid, several more made enquiries, both to the Ministry and to other
companies trying to secure joint venture arrangements with the nationally owned and foreign companies. The exercise
was highly successful, having served its multi-purpose role of:
(i) initiating petroleum exploration in open areas;
(ii) attracting attention to the petroleum potential of Trinidad and Tobago;
(iii) determining investors confidence in Trinidad and Tobago, in terms of both its political stability and
improving fiscal regime.
To determine the success of the bid exercise, we need to recall some important factors:
1.There has not been an offer of open acreage offshore Trinidad and Tobago since 1979. This is a very long time
for an area such as ours, a mature province with low risk potential.
2. The areas offered, although relatively small in size, are of the very low risk category in terms of the likelihood
of a petroleum discovery. This offers an ideal investment opportunity for companies seeking new exploration acreage.
3. It is widely predicted that US oil imports will top 50% of consumption by as early as 1989/1990. With shrinking
domestic production and reserves, major US and international oil companies are seeking close and reliable sources
of replacement supplies.
4. The discovery of the highly prolific El Furrial trend in Eastern Venezuela has opened up a vast new exploration
concept for the Eastern Venezuela Basin (in which Trinidad and Tobago's oil producing provinces lie). With
no imminent opening up of Venezuela's industry to foreign investors, the oil companies have looked to the
most easily accessible extension in Trinidad and Tobago for exploration.
From the period leading up to the official announcement, and until the closing of bids, the Ministry was overwhelmed
with companies visiting to review data and discuss the geology and fiscal and legal systems of Trinidad and Tobago.
In all, about 30 oil companies either visited, wrote or called the Ministry for information about open areas in
1987 and ea4y 1988. Since the first bid round has closed, about one dozen service companies are reported to
have made moves to be registered locally, and as many oil companies have visited the Ministry to look at data for
the upcoming bid round.
5. Several oil companies have had very good cash flows in recent times, leaving them with surpluses to invest.
Trinidad and Tobago's exploration history, the large tracts of open areas sitting in the middle of, and on trend
with, producing fields, and our strategic geographic location made this an attractive opening for the oil companies.
The 1987 offer was seen as necessary to halt the declining levels of production in Trinidad and Tobago by promoting
exploration activity. It was critical therefore that everything went smoothly. Staff at the Ministry had to determine
that the timing of the offer was optimal, so as not to coincide with other offers regionally or worldwide. The
major oil companies have fairly small new ventures or negotiation groups, so for a new country, which Trinidad
and Tobago is to most of them, there must not be too many simultaneous activities of this sort.
The Ministry also had to market the potential of the blocks and the data package - all without a budgeted allocation.
The data preparation and packaging were done in-house. The final data package comprised some 25 kg of printed matter,
including 2700 km of seismic lines. This exercise was widely seen within the Ministry as a sort of dry run for
the later, bigger bid rounds, where a mixture of blocks, ranging from high risk, high potential to low risk, low
potential, would be offered.
Of the 18 companies eligible to bid, by virtue of having paid the US$25,000 fee (see Table 1) only 6 actually did
offer a bid (Table 2). Some of the possible reasons for this were identified as:
(i) the time to evaluate the data (2 1/2 months) was too short;
(ii) the blocks were too small to be attractive to some investors, others were not impressed by the potential based
on the available data;
(iii) some potential investors preferred to wait and see the outcome of this bid round before making a commitment;
(iv) some were unsure of the role of the State companies and of the government's view of foreign company investment.
A policy statement on this was seen as a possible inducement for future bidding rounds;
(v) the prospective structures of the U-shaped block cross the limbs of the block, in such a way as to leave much
of the prospect within the area enclosed by the U, an area currently under licence to Amoco Trinidad Oil Company.
Because of the wide variety of environments involved - from a land block (the last major contiguous land area in
the Southern Basin) to deep water (750 m) areas, from the Northern Basin extension to the East Coast extension
- this upcoming round promises to be exciting and to hold the key to Trinidad and Tobago's petroleum potential
for the next few years. Investors will tend to be cautious because of the risk involved in testing new play
concepts, but with the potential return so large in any of these blocks keen competition is again anticipated.
Mr. Paul concluded that in order to promote this competition it is essential to avoid repeating the errors of the
first round by making available to interested companies good quality data and adequate time to evaluate the blocks.
Indeed this will redound to the benefit of all in the long term.
7. STRATIGRAPHIC COMM ITTEE
J. Framton (Trinmar)
For the first time since December 29th, 1955 a group of geologists has met to discuss a stratigraphic lexicon for
Trinidad and Tobago. In 1955 the meeting finalised the manuscript for the Trinidad and Tobago sections of the Lexique
Stratigraphique International, Amerique Latine, which was published in 1956. The notes on that 1955 meeting are
reproduced here in order to provide the necessary background and perspective to the formation of the present Stratigraphic
Committee.
1955 MEETING: Present were: S.T. Waite, W.A. Van den Bold U.B.O.T.); C.C. Wilson, A.E. Wirz (T.P.D.);
M.C. Robinson, H. Kaska (Dominion Oil); G.W. Baxter (Apex); G.C. Richards (K.T.O.); K.W. Barr, H.M. Bolli, T.H.
Bower, H.G. Kugler, K.Rohr, J.B. Saunders (T.L.L.).
In welcoming members, Dr. Barr said that the meeting had been called for the purpose of discussing a Stratigraphic
lexicon for Trinidad prepared by Dr. Kugler. At the 19th International Geological Congress the Commission of Stratigraphy
was requested to compile a Stratigraphic lexicon for each country, and the lexicon under discussion would be
a contribution to the International lexicon. It would also be used in Dr. Kugler's Treatise on the Geology of Trinidad,
and would serve as a basis for the future stratigraphy of Trinidad.
Dr. Kugler extended a cordial welcome to members. He said that the last meeting of this kind took place on 22nd
September, 1921. Among the geologists who took part in that discussion were Prof. Harris, Mr. Waring and Mr. Penny,
and those present now were about to perform a task similar to that done at the meeting of September 1921. It was
regrettable that minutes of the 1921 meeting could not be found, but fortunately he had his own notes of the meeting
and to which reference can be made if necessary.
Before starting the discussion on the various items it was necessary to have one point clarified namely the definition
of the term "Formation", particularly in reference to Trinidad conditions where "Wild-flysch"
sedimentation had resulted in the occurrence of large, rootless masses, many of which were stratigraphically important.
In order to include some such units as formations Dr. Kugler suggested that, for the purposes of Trinidad stratigraphy,
a formation could be defined as a unit outcropping over a distance of 50 feet and which should include one or a
sequence of beds of differing lithology, whereas a block would consist of a uniform lithologic type regardless
of size.
After some discussion it was the opinion of the meeting that the accepted international definition of a formation
could not be modified, but that for the present purposes each of the questionable formations should be considered
on its merits and defined accordingly.
On this basis the Lexicon was reviewed and the majority of the formation definitions were accepted. A number
of changes in status of formation units were agreed.
1988 STRATIGRAPHIC COMMITTEE:
Although over 32 years have passed since then, the notes prepared after the 1955 meeting show that the last meeting
of this kind took place on 22nd September 1921 and it is possible that changes in, and additions to, stratigraphic
nomenclature are normally so few, or evolve so slowly, that revisions are only required after decades have passed.
However the years since 1955 have seen major changes, with knowledge having been gained in areas that were
then inaccessible: for example, the marine areas that have been drilled off both the north and east coasts. Even
in the Gulf of Paria the Soldado no.2 well was not yet drilled in 1955, although the discovery well was completed
by then.
The Geological Society of Trinidad and Tobago (GSTT) has therefore recognised the need to formalise stratigraphic
terminology for the new areas, and to revise, where necessary, existing definitions so that all geoscientists working
in Trinidad and Tobago may have a common language.
To this end a Stratigraphic Committee was formed with Dr. John Frampton as Chairman. The first meeting was
held on Tuesday 19th April when it was decided to work towards both a new lexicon and a field guide. Two sub-committees
were formed from the members of the main committee as follows:
Lexicon Field Guide
J. Frampton J. Frampton
B. Carr-Brown W. Ah
J. Keens-Dumas P. Farfan
C. Telemaque J. Scott
E. Williams
It was also agreed that the GSTT should approach the oil companies operating in Trinidad for the release of stratigraphic
charts, definitions, etc., for the use of the Committee.
Further, it was felt that a recommendation should be made to the GSTT to set up a permanent committee, outside
of the present one, that would arbitrate on the reliability of new stratigraphic nomenclature concerning Trinidad
and Tobago. It is hoped that the existence of this committee would keep unnecessary duplication and/or uncorrected
errors from entering the scientific press.
For the benefit of the members of the GSTT it is envisaged that parts of the lexicon and field guide will be published
in the Newsletter as they are completed. Comments will be invited so that revisions may be made before publication.
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THE GEOLOGICAL SOCIETY
OF TRINIDAD & TOBAGO
P.O. Box 3524, La Romain, Republic of Trinidad and Tobago, W.I.
