PANEL DISCUSSION held on GSTT Day February 8th 2006
:
"Towards a Trinidad Basin Stratigraphic
Nomenclature"
Panelists included:
- Laurent DeVerteuil (Latinum)
- Steve Herteg (EOG Resources)
- Chris Isaac (BG T&T)
- Curtis Archie (Petrotrin)
Curtis began the discussion with a brief introduction into the history of the work done on the
stratigraphy of Trinidad:
- Stratigraphic lexicon - Kugler 1959
- Treatise of Trinidad Geology - Kugler 1996
- Geological map of Trinidad - Kugler 1959
- Geological map of Trinidad - Saunders 1997
- New Geological map of Trinidad - Snoke et al 1990
- It was noted that the Treatise ignored the geology of the Northern Range and Tobago.
- During the 1980's there was a stratigraphic committee set up to examine all aspects of the
stratigraphy of both Trinidad and Tobago.
- In 1939, Kugler, at the 1st Geological Conference did a "Tentative stratigraphic correlation
table for Trinidad".
- In 1979, Karr Brown and Frampton, at the 4th Latin American Geological Conference, did
the current stratigraphic chart for onshore Trinidad, and attempts were made to tie the
stratigraphy into Venezuela.
- In the late 1980's, Amoco did their correlation chart, and in 2000, Wood et al showed how
stratigraphy was defined using biostratigraphy.
Chris then continued with a few questions and suggestions to the panel:
- What is the framework for the stratigraphic committee and the deliverables?
- Will the Ministry of Energy assist?
- What is the stratigraphic framework and biosystem etc?
- He suggested that type localities and wells be used
Steve:
- The main goal should be to have communication between the different companies and the
Government
- In terms of scale, he said that Trinidad is geographically small but geologically complex.
- We need to bring together chronostratigraphy and lithostratigraphy.
- We need to take into account the depositional chronostratigraphic framework, and the
amount of sediments offshore vs. onshore.
Laurent:
- An important concept is History vs. Synthesis
- This should be an on-going project and it should be available to the membership as a webbased electronic database, rather than something published.
- If it is to be published it should be done at a very low cost or for free.
- Communication is important in this project.
- The Ministry input is needed, and the releasing of data is an important factor.
- New technical studies should be encouraged, but this is not necessarily the job the
committee, but rather that of the GSTT.
- We need to agree on a format and framework on a way forward.
Curtis:
- The aim is not to publish a new Treatise.
- Things need to be understood and organized.
- All views need to be included.
Laurent:
- He noted that no one person is working with all the data, so the data cannot be fully
synthesized.
- We need Petrotrin support since they hold most of the data on land.
- We need the support from all the top managers from the companies.
It was also noted that we need to show the viability of the project. The question was raised as
to what vehicle is this synthesis going to take, be it maps, or posters etc. The project has to in
the best interest of the geoscientists in Trinidad.
Points for Stratigraphic discussion
Since the publication of the Stratigraphic lexicon for Trinidad and Tobago in 1959 by Kugler,
thousands of wells have been drilled throughout the country and significant new
biostratigraphic and petrologic work has been done. The Treatise of Trinidad by Kugler in
1996 while it was more detailed in how the Formations were defined did not cover the
Cretaceous and older rocks or incorporate any new work pose 1950's. The Surface geology
map of Kugler 1959 represented the cumulative work of many geologists and marks a
significant point in Trinidad geology. The "updated" Saunders (1997) made few significant
changes to the map and ignored much work by local geoscientists. This Stratigraphic
Committee proposes to examine all aspects of the stratigraphy of Trinidad and Tobago in
attempt to have a uniform methodology of identifying and describing our rocks that conforms
to international standards, thus removing any confusion when geoscientists meet.
The GSTT did have a stratigraphic committee in the 1980's but no records can be found for
their deliberations, we hope that past members of that committee can give a summary of what
transpired. What we would like to do today is to identify areas of concern and problems that
members have encountered.
Some examples of possible topics for discussion:
" Work by previous committees
" Lithostratigraphy, biostratigraphy & chronostratigraphy - how have our Formations been
defined and are they still valid?
" The Cretaceous: the Couva Evaporties (not covered by lexicon), age of the Naparima Hill
Fm, Northern Range meta-sediments (Toco)
" The Cunapo Conglomerate
" Age of Formations - biostrat vs. zircon dating
" New stratigraphy encountered post 1959
" Sequence stratigraphy & sea level changes - can we use the sea level curves of Haq to
derive absolute ages for events in a tectonically active basin
" Proposed changes to surface geology map
" The Herreras - deepwater vs. shallow water origin, north derived vs. south derived source
" The Narivas - deepwater vs. shallow water origin, north derived vs. south derived source
" The San Fernando Formation - biostrat vs. zircon dating
" The "Cherry cake conglomerates" - origin and age
It is hoped that at the end of the days discussions that a prioritised list of topics for detailed
work will be arrived at, also all comments and contributions will be recorded for distribution to
all participants.