| Popis: |
One of the main northern South American geological conundrums has been to establish the tectonic relationship between Caribbean and South American plates during Mesozoic and Cenozoic times. Based on the petrogenetic interpretation of magmatic bodies within the Maracaibo block, we suggest an interplay between subduction and overthrusting tectonics in the northern part of South America during the Cenozoic. Our data show that the subduction of the Caribbean Plate beneath the South American Plate started around 65 million years ago, as is evidenced by the presence of trondhjemitic intrusions in the Santa Marta Province. Then, after a ca. 5-million-year magmatic gap, the evolution of this subduction system allowed the formation of a magmatic arc represented by the calc-alkaline Santa Marta Batholith (~56–49 Ma) and Parashi Pluton (51–47 Ma). For the interval between 50 and 25 million years, our data and compiled data point to a reduction in the tectonic activity, which is supported by relatively slow rates of cooling and uplifting in the Maracaibo block. Finally, for the period since the early Miocene, the reported uplift data, subsidence rates, and stratigraphic discordances indicate a differential uplift of the Maracaibo block, decreasing from the northwestern tip (Sierra Nevada de Santa Marta) toward the southeast (Merida Andes) and suggesting that this tectonic “reactivation” is the result of dominant overthrusting tectonics. |
