Late Cenozoic uplift and paleogeography of the Colombian Andes: constraints on the development of high-andean biota

Abstract

An analysis of published and newly obtained data on the timing of uplift in the Colombian Andes shows that some areas were already uplifted above the (present) forest line as early as 16 Ma ago. Elsewhere early uplift data (Oligocene- Mid-Miocene) have only been obtained from elevations below 3000m. Most other areas above 3000 m reached their present altitude only after 6-4 Ma ago by more recent uplift or by the formation of stratovolcanoes on dissected planation surfaces. Accretion of the Panamanian isthmus between 7-3 Ma may have been contemporaneous with the latter, most vigorous Plio-Pleistocene uplift phase in the northernmost Colombian Andes but cannot be related to the earlier phases in the whole Andean chain. The accretion enabled immigration of holarctic species into the Andes. There is no reason to suppose a topographic interruption in the Andean Chain at the Huancabamba deflection during the Tertiary, and hence immigration of australantarctic species depended only on the presence of suitable high-Andean climatic conditions along the whole of the Andean chain.