NEOGENE BIOME RECONSTRUCTION FROM NORTHERN VENEZUELA

We present preliminary results of a high resolution palynological analysis of the Urumaco trough, Northern Venezuela. The entire sequence consists of 9 km of sediments accumulated in a subsidence trench that originated with the collision of the Caribbean and South America plates. The long sedimentary record expands across an area of 50 km² and allows for paleoenvironmental reconstruction over the last 17 Ma. Analysis of palynomorphs and facies at stratigraphic depth intervals of less than 60 m provide data on likely changes in biomes and environmental conditions from the early Neogene to Pleistocene in the Falcon area.

The climatic history of the region, including the timing of the onset of these arid conditions and the evolution and establishment of this local xeric biome are still largely unknown. These arid climatic conditions were likely influenced by changes in ocean circulation initiated by the formation of the Panamanian Isthmus. Current regional climatic conditions are strongly governed by the annual migration of the Intertropical Convergence Zone (ITCZ), by westerly wind patterns, and by El Nino and Southern Oscillation (ENSO). Regionally, there is extensive aridity that extends from the Guajira peninsula and all the way west to the Falcon state, including the Paraguana Peninsula. The xeric environment that dominates the area supports vegetation that exclusively thrives under stressful climatic regimes.

Our initial paleovegetation and paleoenvironmental reconstructions support the hypothesis of a change in the vegetation towards a xeric dominating type as a response to a striking climatic shift that induced a arid conditions in the area by the late Miocene.