Project

Back to overview

Integrated bio/geo-chronology and paleo-environments of Paleogene short-lived carbonate shoals (SLSC) on active margins of the Caribbean Plate - relations with tectonic and volcanic processes

English title Integrated bio/geo-chronology and paleo-environments of Paleogene short-lived carbonate shoals (SLSC) on active margins of the Caribbean Plate - relations with tectonic and volcanic processes
Applicant Baumgartner-Mora Claudia
Number 185067
Funding scheme Project funding (Div. I-III)
Research institution Institut des sciences de la Terre Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geology
Start/End 01.09.2019 - 31.08.2022
Approved amount 270'208.00
Show all

All Disciplines (2)

Discipline
Geology
Palaeontology

Keywords (9)

Paleogene; Caribbean Plate; short-lived carbonate shoals; volcanism; tectonic processes; Active margins; Larger Benthic Foraminifera; biochronology; geochronoloy

Lay Summary (French)

Lead
Les bancs carbonatés éphémères (BCE) du Paléogène des marges actives caraïbes se caractérisent par leur petite taille et la brièveté des conditions de production de carbonate par des organismes photosynthétiques (algues rouges, grands foraminifères benthiques, GFB, à symbiontes). Encore mal connus et mal datés, les BCE diffèrent du modèle des grandes plateformes carbonatées Bahamiennes qui se développent dans les marges passives. En effet, ils semblent plus contrôlés par des processus tectoniques et volcaniques que par les changements eustatiques du niveau marin.Ce projet a pour but de comprendre la réponse biotique aux évènements tectoniques et volcaniques qui est enregistrée dans les BCE. Ces événements sont en relation avec l'accrétion aux marges actives d'îles océaniques et de plateaux.
Lay summary
Lead

Les bancs carbonatés éphémères (BCE) du Paléogène des marges actives caraïbes se caractérisent par leur petite taille et la brièveté des conditions de production de carbonate par des organismes photosynthétiques (algues rouges, grands foraminifères benthiques, GFB, à symbiontes). Encore mal connus et mal datés, les BCE diffèrent du modèle des grandes plateformes carbonatées Bahamiennes qui se développent dans les marges passives. En effet, ils semblent plus contrôlés par des processus tectoniques et volcaniques que par les changements eustatiques du niveau marin.
Ce projet a pour but de comprendre la réponse biotique aux évènements tectoniques et volcaniques qui est enregistrée dans les BCE. Ces événements sont en relation avec l'accrétion aux marges actives d'îles océaniques et de plateaux.

Objectifs et buts de la recherche

- Caractériser les biofaciès et les discordances encaissantes des BCE.
- Améliorer la datation bio- et géo-chronologique des BCE.
- Établir des relations spatio-temporelles entre les BCE et les évènements tectoniques et volcaniques locaux et régionaux.
- Créer un nouveau modèle pour la formation des BCE.
- Reconstruire la paléogéographie de l'isthme de l'Amérique Centrale durant 120 Ma.

Contexte scientifique et social du projet de recherche 

La biochronologie des GFB de la bioprovince américaine, principal outil de datation, est encore mal établie et mal calibrée. La migration des formes endémiques des BCE doit être élucidée. Les BCE peuvent constituer des réservoirs économiquement importants d'hydrocarbures ou d'eau. Un nouveau modèle pour les BCE permettra de prévoir la taille, la géométrie et la qualité des réservoirs. La reconstruction du climat et de la circulation océanique au Paléogène dans le passage caraïbe, permettra de réévaluer le potentiel en hydrocarbures des régions étudiées.

Direct link to Lay Summary Last update: 03.04.2019

Responsible applicant and co-applicants

Employees

Name Institute

Project partner

Associated projects

Number Title Start Funding scheme
162670 Tethys-Atlantic-Panthalassa, Global Mesozoic ocean fertility, silica burrial and radiolarian biochronology 01.10.2015 Project funding (Div. I-III)

Abstract

This proposal seeks for funding of a 3-years project including one PhD candidate to work on Palaeocene to Oligocene small scaled and short-lived carbonate shoals (SLCS), widespread along the active margins of the Caribbean Plate. The growth of Caribbean SLCS seems to be largely controlled by tectonic and volcanic processes, rather than eustaic sea-level changes, but they are today poorly understood and dated. Caribbean Paleogene SLCS are characterized by a rapid appearance and disappearance of stable conditions favourable to chlorozoan carbonate production, modest size and a geologically short life span. SLCS were mainly built by rock-forming Larger Benthic Foraminifera (LBF) and coralline red algae, while coral frameworks seem to be restricted to some Oligocene formations. SLCS are fundamentally different from long-lived, large carbonate shelves set on (often thinned) continental crust along passive margins, such as Florida, Yucatan, Nicaragua Rise etc. Hence, sedimentological models developed for the latter do not apply to SLCS. At best, they can be compared to modern guyots or atolls. Oceanic basements, such as basaltic plateaus, oceanic seamounts and proto-island arcs formed at aphotic depths and subsided thermally, unless tectonic or volcanic activity produced uplift or buoyancy to make them temporarily reach the photic zone. Once oceanic or arc rocks reached the subaerial realm - either by accretion/collision or in volcanic edifices - they were highly affected by tropical weathering, producing high discharge of clay and silt into the surrounding seas. In addition, explosive volcanic activity of island arcs produced suspended ashes in surface waters, as well as abundant dissolved nutrients, creating unfavourable conditions for the growth of SLCS. Local or regional upwelling may also have enhanced eutrophication of surface waters. Hence, the formation of SLCS could take place only under special conditions, such as rapid tectonic uplift and subsequent subsidence, the stalling of nearby volcanic activity and/or the bypassing of siliciclastic sedimentation. Biofacies and accurate dating of the rapid appearance and disappearance of chlorozoan carbonates on uplifted accretionary prisms, island arcs and intra-plate volcanoes, as well as the nature of encasing detrital sediments, will provide valuable markers for of the tectonic, geodynamic, and paleo-environmental evolution of oceanic islands and active margins of the Caribbean Plate.Peculiar, partly endemic assemblages of LBF, a main constituent of SLCS, are difficult to date, because the recently proposed biozonations for LBF are based on Tethyan taxa and are not applicable to Caribbean SLCS. Polyphyletism and parallel evolution of foraminiferal lineages do not allow, at this stage, biostratigraphic correlation between the two bioprovinces. Plate tectonic reconstructions predict important longitudinal displacement of many SLCS. Their paleo-geographic position may help to elucidate paleo-biogeographic extension for LBF, since SLCS served as "stepping stones" for the migration of benthic communities.Based on our previous work of the last two decades, we plan to improve the Eocene biochronology based on Larger Benthic Foraminifera (LBF) characteristic of the Caribbean Realm. We also need independent chronologic calibration of SLCS and their LBF assemblages by other fossil groups (i.e. planktonic foraminifera, nannofossils), stable isotope (C, O. Sr) stratigraphy, and radiogenic isotope (Ar/Ar) dating of volcanic and intrusive rocks frequently associated with SLCS. Based on our previous reconnaissance work, we plan field campaigns in S-Central America and the Antilles, in sections where SLCS are interbedded with volcanogenic sediments, lava flows or intruded by well-crystallized sills/dykes, that will allow for Ar/Ar-dating of mineral separates.
-