Palynostratigraphy and paleoecology of five Cauca slim wells, NW South America in the Cauca-Patia Basin, SW Colombia.

NAVARRETE, R.; DI PASQUO, M.M.; MEJÍA-MOLINA, A.

La Plata

Simposio; XVI Simposio Argentino de Paleobotánica y Palinología; 2015

universidad nacional de La Plata y Museo

The Cauca-Patia upstream Basin (1°20? and 5°5? N latitude) is an elongated Intermountain depression, which separates the Western and Central Colombian ranges situated to the north of South America. This paper presents palynological data to illuminate the structure of oil and/or gas bearing beds within the basin. The studied sediments (123 core productive samples) from 3.480 feet thick succession of Cauca-11 (536,8-340,9 ft), Cauca-12 (57,5-1.479 ft), Cauca-17 (212-889 ft), Cauca-32 (124,9-1310 ft), and Cauca-33-TWIN-1 (903,5-2614,8 ft) slim wells, yielded abundant, well preserved and diverse terrestrial angiosperms (47 species) and spores (57 species) over gymnosperms (2 species), fungal spores (11 species), and algae (7 species). Scarce dinoflagellate cysts (7 species), foraminifera and calcareous nannofossils are also recorded. Combined palynology and foraminifers indicate that transgressive-regressive phases led to quite variable depocenters ranging from upper shorefaces of coastal flood-plain and ponds in alluvial plains and a vegetation of humid forest ferns complex to littoral marine settings with mangrove, swamp and marine marshes type peat bog. Eight palynological zones spanning the Late Oligocene to Early Pleistocene are identified: Cicatricosisporites dorogensis, Horniella lunarensis, E. maristellae, Grimsdalea magnaclavata, Crassoretitriletes vanraadshooveni, Fenestrites spinosus, Cyatheacidites annulatus, and Fenestrites longispinousus Zones. These results are part of oil and/or gas exploration ANH protocols and provide a realistic support for the expensive operations of petroleum prospecting. (*) This contribution was derived from several results obtained for the ?Agencia Nacional de Hidrocarburos? (ANH), Colombia in the context from 153 de 2012 ANH-Antek contract.