MINERALOGY AND AGE OF A NEWLY-MAPPED GALAPAGOS SEAMOUNT

The Galapagos Archipelago is well known for its islands but there are also a variety of seamounts produced by the hotspot and its interaction with the nearby Galapagos Spreading Center. During the 2010 R/V Melville MV1007 cruise, a large seamount located south of Isla Marchena was mapped for the first time. The main focus of this presentation is to report new data to help determine its geologic history (mechanisms of formation, age, and movement over time). Composition and backscatter images were obtained using electron microprobe for several of the basalts recovered from the three dredge sites on the seamount. In addition, three new ⁴⁰Ar/³⁹Ar ages show that the eruption age of the lavas ranges from ~1 to 2 Ma ± 0.5. These ages suggest that the seamount was originally an island that was located approximately 100 km west from its present position.