QUANTITATIVE BIOSTRATIGRAPHIC MODEL FOR THE TERTIARY OF THE LOWER MAGDALENA BASIN, COLOMBIAN CARIBBEAN

• Main Authors: Carlos Cuartas, Carlos Jaramillo, José Martínez
• Format: Article in Journal/Newspaper
• Language: English
• Published: Instituto Colombiano del Petróleo (ICP) - ECOPETROL S.A. 2006
• Subjects: tertiary; quantitative biostratigraphy; graphic correlation; planktonic foraminifera; geology calibration; Cuenca del Valle Inferior del Magdalena; Energy industries. Energy policy. Fuel trade; HD9502-9502.5; Chemical engineering; TP155-156; Kendall; Planktonic foraminifera
• Online Access: https://doaj.org/article/e64eea6a4bd44409949603f438b03137

The reinterpretation of biostratigraphic information by new models and quantitative correlation techniques substantially improves its resolution and its correlative potential, thus minimizing oil exploration risks. With this aim, biostratigraphic information, i.e. first (FO) and last (LO) occurrence events of benthonic and planktonic foraminifera was analysed from sixteen wells from the Lower Magdalena Valley (LMV). The inconsistencies found in the biostratigraphic record, i.e. varying successions of first and last appearances of species from well to well as a result of several factors such incomplete sampling and preservation, true variation in the distribution of fosil taxa, etc., and the great amount of biostratigraphic data makes it practically impossible to accurately constrain basin history from biostratigraphic information by unaided visual inspection. This motivates the treatment of biostratigraphic information with new quantitative approaches, such as constrained optimization (CONOP9 software) and graphic correlation concepts (GraphCor 3,0) and the comparative method approach of Cooper et al . (2001). The succession of biostratigraphic events found through the application of each technique was statistically filtered and compared with Kendall tau coefficients whose values were 0,8. An optimal biostratigraphic succession of LOs was found and calibrated with the Berggren et al . (1995) global time scale by a LOESS regression model for the middle Eocene-Pliocene interval, thus revealing three major changes in sediment accumulation rates for the basin during this time interval: (1) middle Eocene to Oligocene, with low accumulation rates, (2) early Miocene to middle Miocene, with high accumulation rates and (3) late Miocene to Pliocene, with lower accumulation rates. The calibrated composite succession enabled the construction of age-well depth plots, which indicate periods of local deposition and accumulation rates, and periods of erosion, no deposition or very low accumulation rates (unconformities). The ...