CICTERRA   20351
CENTRO DE INVESTIGACIONES EN CIENCIAS DE LA TIERRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Lacustrine Organic Matter (LOM) in a saline to hypersaline system: Tracking the relationship between modern depositional environments and organic matter formation and distribution
Autor/es:
L. COIANIZ1, D. ARIZTEGUI1, E. PIOVANO2, P. GUILIZZONI3 AND A. LAMI3
Lugar:
Viena, Austria
Reunión:
Congreso; EGU2008; 2008
Institución organizadora:
EGU
Resumen:
Strategies behind oil and gas prone exploration have been traditionally relied upon
the presence of marine source rocks. The last quarter of the 20th century, however,
was marked by a major development of lacustrine source oil fields in several areas of
Africa, Australia, Brazil, China, Indonesia, Russia and the western United States. As a
consequence, there has been an increasing interest to characterize depositional settings
of these oil generative sequences and their modern analogues. Most of the current-day
lacustrine source-models for petroleum exploration are based on the Green River Formation
that represents the maximum expansion of the Eocene freshwater Lake Uinta.
Hence, these new developments are challenging original interpretations concerning
organic facies characterization and distribution. As a result, there is an urgent need
to develop alternative analogue models that can be used in different areas. The goal
of this study is to foster a new model for lacustrine organic matter (LOM) formation
and deposition, with special emphasis on understanding the complex relationship
between environmental factors, lake level fluctuations, water chemistry and organic
matter production/preservation. Located in the Pampean plains of central Argentina,
Laguna Mar Chiquita is a closed-lake basin that has evolved in a tectonic depression
formed during the Pleistocene. At present, it is the biggest saline to hypersaline lake
in South America (6000 km2). One of the most relevant features of this lake are the
large water levels fluctuations induced by changes in rainfall particularly since the
second half of the 20th century. Decadal variability in the water budget have dramatically
affected primary productivity, mineral precipitation, sediment distribution and
associated biological processes in the lake system which has been historically- and
instrumentally-recorded. Petrophysical, sedimentary and organic geochemical analyses
in a series of well-dated sedimentary cores provide us with unique information
to model LOM facies distribution. Pigments preserved in the sediments are used to
investigate the organic matter delivered to the basin allowing to identify the source
and quality of the LOM and further evaluate its potential to generate hydrocarbons.
This model can be further applied to the exploration and development of oil fields at
different time windows such as those associated with South Atlantic marginal basins
(e.g., Araripe, Sergipe/Alagoas and Reconcavo in Brazil).