Multidisciplinary Study of the Cuyana Basin, Argentina
Carlos Urien1, Ana Marie Zavattieri2, and Craig Schiefelbein3
1Urien & Associates, Buenos Aires, Argentina
2IANIGLA-CONICET, Mendoza, Argentina
3GSI, Shenandoah, TX
The Cuyana Basin is a pericratonic landlocked intermontaine rift basin covering an area of about 40,000 km2 and containing about 4 km of sediment thickness. It is situated between western Pampean Ranges and eastern Precordillera foothill. The basin is composed of several rifted sub-basins formed during the Triassic as a result of postorogenic relaxation and extension that continued into the Early Jurassic.
Waxy oils produced from Triassic strata constitute one of the oldest and most important petroleum resources in Argentina and are primarily derived from organic-rich shales of the Late Triassic Potrerillos and Cacheuta formations deposited in fluvial-deltaic and freshwater lacustrine environments, respectively. The lacustrine strata are oxic-anoxic stratified levels rich in chlorophytic algae and degraded amorphous organic matter. Significant hydrocarbon generation only occurred during the last 10Ma. following a rapid subsidence episode of thick Tertiary overburden.
The microfloral assemblages are more diverse and abundant than the “Dicroidium” Flora that characterized the Potrerillos and Cacheuta formations and coeval regional equivalents. These highly diversified floristic associations are dominated by gondwanic forms, but also contain some cosmopolitan elements that have been attributed to Late Triassic age.
The present study utilized a multidisciplinary approach to further evaluate and predict the occurrence and distribution of petroleum systems active in this important area. Oil and source rock geochemistry and micro and megafloristic data are integrated within a geological and geophysical framework and combined with recent 2.5D thermal modeling results to understand facies and thermal variability across the basin and to construct a realistic evolutionary model.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas