INTRAPLATE UPLIFT AND BASIN GENERATION ON THE SW CORNER OF THE MARACAIBO BLOCK: DISTAL EVIDENCES OF CARIBBEAN PLATEAU - NORTHWESTERN SOUTH AMERICA COLLISION

During Paleogene, collision process of the Caribbean plateau against the North West corner of South America caused uplifts along the convergent margin (Santa Marta massif and Central cordillera); however, only few evidences have been reported about the effect of this process on the internal segment of the Maracaibo block. An integrated provenance analysis was carried out on the Paleocene-Eocene succession on the Catatumbo Basin, located 300 km from the collisional margin.

The compositional tendencies of sandstone composition (20 samples), heavy mineral assemblages (7 samples) and detrital zircon populations (7 samples), indicate two different tendencies. Quartzose rocks with dominant sedimentary lithic fragments and ultrastable heavy mineral assemblages dominate for the Lower Paleocene Barco Formation and lower to middle Eocene Mirador Formation. Sandstones of the upper Paleocene Cuervos Formation and upper Eocene Carbonera Formation are compositionally immature; include metamorphic and volcanic lithic fragments and unstable heavy minerals (chlorite, Epidote and biotite).

Detrital zircon populations in all the units are quite uniform with dominance of 900-1500 Ma populations. The only difference is the Jurassic populations (ca 190 Ma) and upper Paleocene populations (58-53 Ma), which are documented in Upper Paleocene and Upper Eocene sandstones. Associated with those picks is the increase of feldspar fragments and unstable heavy mineral increase, which suggest a local plutonic input.

Provenance indicators of the Catatumbo Basin differ with similar indicators from the Cesar – Rancheria basins located adjacent to the marginal uplift. In those marginal basins, Paleocene sandstones are compositional immature with high content of metamorphic and feldspar fragments and zircons populations younger than 300 Ma dominate. This suggests that fluvial systems derived from the collisional margin did not reached intraplate basins. Orogenic process associated with the interaction of the Caribbean Plateau and the North West corner of South America, are the main causes for internal breaking of the Maracaibo basin and the establishment of intraplate basins like the Catatumbo basin.