--> Oligocene-Miocene Filling of the Distal Llanos Basin of Colombia; Interaction of Flexural Subsidence, Intraplate Faulting and Dynamic Topography Models, Bayona, German; De Armas, Miguel; Villamarin, Patricia; Mora, Alejandro; Gomez, Elvira; Guerrero, Jairo; Leyva, Ivan; Valencia, Andres, #90100 (2009)

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Oligocene-Miocene Filling of the Distal Llanos Basin of Colombia; Interaction of Flexural Subsidence, Intraplate Faulting and Dynamic Topography Models

Bayona, German1
 De Armas, Miguel2
 Villamarin, Patricia3
 Mora, Alejandro4
 Gomez, Elvira2
 Guerrero, Jairo2
 Leyva, Ivan2
 Valencia, Andres1

1ARES, Bogota, Colombia.
2
Nexen Petroleum Colombia Limited,
Bogota, Colombia.
3
ECOPETROL
S.A., Bogota, Colombia.
4
HOCOL
S.A., Bogota, Colombia.

The Llanos basin of Colombia developed mainly as result of the multi-phase growth of the Eastern Cordillera of Colombia, as depicted by the foreland-type stratigraphy and geometry in its proximal setting. However, basin-filling processes and geometry of the segment between 200 to > 400 kms from the frontal thrust belt of the Eastern Cordillera change dramatically. In addition to the effects of flexural uplift (forebulge) geometry and associated extensional/contractional structures, we also examine the effects of mantle-driven processes related to the onset of subduction, and intraplate uplifts in the southern Llanos basin. The integration of all this processes produced the rapid eastward migration of eastern clastic source areas and abrupt change in filling processes of the basin from continental environments, to lacustrine-deltaic, then to lacustrine in Middle Miocene. Finally, in middle to upper Miocene time, the basin filled rapidly with lacustrine, deltaic to continental deposits coming from cratonic and intraforeland uplifted areas. The irregular distribution of basal Oligocene-Lower Miocene sandstones (reservoirs), that accumulated in continental settings, are strongly controlled by local structures, whereas the flooding of the basin capped uniformly all those reservoir units with a lacustrine fine-grained strata, creating a good seal for oil migration. The rapid flooding of the basin was a combination of both onset of orthogonal subduction along the northwestern margin of South America that also caused the inversion of the entire Eastern Cordillera of Colombia.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil