Pelagic carbonate sedimentation and preservation of paleoceanographic records: study of micropaleontological geochemical proxies and environmental (paleo)climatic archives

• Main Authors: Zarkogiannis, Stergios, Ζαρκογιάννης, Στέργιος
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: National and Kapodistrian University of Athens 2019
• Subjects: Κλιματικές αλλαγές; Οξίνιση των θαλασσών; Πλαγκτονικά τρηματοφόρα; Ανθρακικά πετρώματα; Climate change; Ocean acidification; Planktonic foraminifera; Carbonate sedimentology; Γεωεπιστήμες και Επιστήμες Περιβάλλοντος; Φυσικές Επιστήμες; Επιστήμη των υδάτων; Παγκόσμια και πλανητική αλλαγή; κλιματική αλλαγή; Earth and Related Environmental Sciences; Natural Sciences; Aquatic Science; Global and planetary change; climatic change
• Online Access: http://hdl.handle.net/10442/hedi/48775; https://doi.org/10.12681/eadd/48775

Oceans contain the most active carbon in the world and are second only to the lithosphere in the amount of carbon they store. The oceans' surface layer holds large amounts of dissolved inorganic carbon that is exchanged rapidly with the atmosphere. Carbon enters the ocean mainly through the dissolution of atmospheric carbon dioxide, which is converted into carbonate. Orbitally-forced changes in climate, weathering, continental runoff, oceanic circulation and productivity control the amount of carbonate or clay inputs that are exported to deep-sea regions and are ultimately preserved in sedimentary successions. The most abundant CaCO3 depositing organisms are algae, members of the phylum Haptophyta. From them, coccolithophores account for most of the oceanic carbonate sedimentation and chalk deposits worldwide (Lowenstam and Weiner, 1989). Coccolithophores with modest Triassic origin (Siesser, 1993) evolved calcitic skeletons made of minute scales called coccoliths (Young et al., 1999). Although widespread calcification must have been initiated during the early Cambrian calcium crisis (Brennan et al., 2004), the ecological expansion of coccolithophores, joined in the Middle Jurassic by planktonic Foraminifera with calcitic tests, changed the nature of carbonate deposition in the oceans since for the first time, a pelagic carbonate factory delivered carbonate sediments directly to the deep sea floor. Seafloor cementstones, common in later Triassic carbonate platforms, exit the record as calcifying plankton expand, suggesting that its evolution led to a global decrease in the saturation state of seawater with respect to carbonate minerals (Knoll, 2003).Planktonic foraminifers have, since their origin 140 million years ago, grown from a negligible contribution to a major sink for pelagic carbonate (Deuser et al., 1981; Schiebel, 2002; Schmidt et al., 2003). Schiebel (2002) estimated the contribution of planktonic foraminifera to the global carbonate budget to be roughly 32–80% of the CaCO3 deposited in the deep ...