Abstract:
SYNATLAN (SYNthesis ATLANtic) is a chronostratigraphic data model, which integrates paleomagnetic, isotopic, and biostratigraphic data generated at sites from Deep Sea Drilling Project (DSDP) Leg 11 through Ocean Drilling Program (ODP) Leg 114 in the Atlantic Ocean. SYNATLAN's objective is to provide numerical age-depth models for Atlantic DSDP/ODP Sites covering the time span from late Cretaceous to Quaternary. The biochronostratigraphic data set is based on the TOTAL ATLANTIC RANGE of species (TARS). SYNATLAN is a contribution to the Ocean Drilling Stratigraphic Network (ODSN). Biostratigraphic, magnetostratigraphic and isotopic data have been used to establish a joint chronostratigraphic database for 159 DSDP/ODP drillsites in the Atlantic. The paleontological data set includes local stratigraphic ranges of calcareous nannoplankton (coccoliths), planktonic foraminifers, Bolboforms, radiolarians, silicoflagellates, diatoms and dinoflagellates. TARS consists of a total of 18,380 last occurrences (LO) out of 4,317 different species and a total of 18,484 first occurrences (FO) out of 4,427 different species. By using a graphic correlation method we have integrated the various data sets for each site in a composite reference section. The age calculations of the composite reference section are based on a defined time scale and were used for the subsequent development of age-depth models for the investigated sites. To introduce the potential possibilities of SYNATLAN, examples such as the occurrences of species among the different groups will be briefly discussed in time slices of 1 million years since late Cretaceous. These time slices of different groups document environmental trends for the Atlantic region. Calcareous nannoplankton (coccoliths) and planktonic foraminifers indicate gradual FO and LO variations, especially for the K/T boundary, suggesting that a believed drastic extinction of species at the K/T boundary cannot be seen in the marine records. Furthermore, SYNATLAN's age-depth models have been used to identify hiatuses and to determine their duration. Hiatuses are an important feature in the calculation of sediment mass balances, since they indicate time intervals of physical and chemical erosion. The distribution of hiatuses and their temporal pattern through time will be briefly discussed in broad terms of global tectonic and paleoceanographic settings.