The Campanian and Paleogene ("Greenhouse") Arctic Ocean paleoenvironment: Implications from organic-carbon and biomarker records (ACEX-IODP Leg 302)

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The 200m thick sequence of Campanian, late Paleocene and middle-early Eocene age, recovered during IODP Expedition 302 (Arctic Coring Expedition - ACEX) on Lomonosov Ridge, are characterized by high organic-carbon contents of about 1 to 6%. Our organicgeochemical study of these unique sediments focuses on the organic-carbon cycle and its relationship to the long- and short-term paleoenvironmental/paleoceanographic evolution during this time interval. Here, euxinic conditions and terrigenous input are the most important processes controlling organic-carbon deposition, as shown in our ongoing study. In the remaining time of our project, the reconstruction of sea-surface temperature changes during middle Eocene times (50 to 44 Ma) using alkenones, and its correlation with the history of Arctic ice-rafting as well as the global temperature curve, will be of special interest. Furthermore, changes in anoxia, freshwater discharge, productivity, and terrigenous input across major extreme climate events identified in the ACEX record, such as the Paleocene/Eocene Temperature Maximum (PETM) Event, the Elmo Event, and the Azolla Event, will be a major focus of our detailed biomarker studies. Applied methods concentrate on biomarker analyses using GC and GC/MS techniques, and stable carbon (and hydrogen) isotopes of specific biomarkers.