Calcareous nannofossil biostratigraphy of Neogene Lower Magdalena Valley Basin-LMVB (Colombian Caribbean): new multi-proxy data from Porquero Formation as a potential hydrocarbon source

Abstract

The Porquero Formation is one of the potential Cenozoic sources of hydrocarbons in the Lower Magdalena Valley Basin-LMVB (Colombian Caribbean). Sediments typical described include in situ pelagic and hemipelagic regimes in a deep ocean floor environment. Two wells belong this formation was sampled for calcareous nannofossil analyses: the P-16 and P-18. Precision and accuracy of nannofossil biostratigraphic correlations have been applied extensively and many events have been calibrated by orbital stratigraphy. The resulting biostratigraphy proposed in this study corresponds to Oligocene/Miocene transition to mid Miocene, which are in agreement with that obtained in recent studies performed by University of Salamanca. This study presents new unpublished data improving the biostratigraphic framework available with direct applications for oil exploration. Continental to deepest marine facies have been studied by integrating of other micropaleontological proxies (pollen and foraminifera) indicating an important supply of organic matter to the basin, and consequently potential source rock. Analyses performed in this work have given an average TOC of 1.83 % (30 samples). The warm phase of the early Miocene peaked in the Middle Miocene Climatic Optimum (17-14.5 Ma) is reflected in the microfossil assemblage and in the abundance patterns, and represent a potential key for future paleoceanographic investigations.