BrasCretOst II

Interactive Visual Identification Tool for Pre-Salt Ostracods (Buracica to Alagoas Local Stages) – VITO The so-called “Pre-Salt” successions comprise a series of geological formations having formed in ancient lakes during Early Cretaceous times between eastern South America and West Africa due to the early successive breakup of Gondwanaland (between ca. 143–115 millions of years ago). During the time interval between ca. 115–110 million years ago, as the rifting continued, marine waters of the – then separated – South Atlantic and Central Atlantic oceans successively advanced towards equatorial regions. Resulting from a combination of factors including the position at – or proximal to – equatorial regions, a global greenhouse climate, generally low water depths and continuing continental drift and subsidence, much of the sea water evaporated resulting in major successions of evaporite (salt deposits) of up to 2000 m. The organic-rich deposits of these ancient long-term lakes, having developed before the evaporite deposition are therefore summarized under the term “pre-Salt” deposits. Today, they comprise a significant proportion of the world’s hydrocarbon reserves and are, thus, of interest for hydrocarbon exploration and exploitation – particularly since they contain light oil of high quality, of high commercial value and of fundamental economic importance for eastern and northeastern South American countries such as Brazil. Since the respective deposits are located 100–150 km offshore Brazil in ultra-deep waters of the Atlantic Ocean (~ 2000 m) as well as under ca. 1000 m of “post-Salt” deposits and ca. 2000 m of salt deposits, target depths for exploration and exploitation range between 5000 m to 7000 m. Therefore, exploration and exploitation of the oil face several technical, environmental and economic challenges. The Brazilian majority state-owned Oil Company Petrobras leading in this field worldwide. Ostracods are mainly aquatic microcrustacean, typically around 1 mm in size, with a calcified bivalved shell, the carapace, that today inhabit virtually all aquatic environments, both marine and non-marine.