Heiko Hüneke

Pelagic Sedimentation in Modern and Ancient Oceans

Abstract In the open ocean pelagic sedimentation occurs at various scales. As a background signal, the everyday process is a rather slow and continuous rain of biogenic debris produced mainly by the planktic flora and fauna in the upper part of the water column. In addition to this, distinct regions of the oceans reveal pronounced, short-term, often seasonal sedimentation pulses following biogenic bloom events, such as the yearly coccolith blooms starting at low latitudes in late spring to early summer and spreading out into higher latitudes during summer and early autumn. A significant portion of this material, consisting of calcareous and siliceous skeletal remains as well as soft organic tissue, reaches the sea floor under the influence of gravity as marine snow and fecal pellets. This chapter presents an overview of the principal factors that control this pelagic flux through the water column and determine the character and distribution of the resulting deep-sea sediments. All modern biological groups that contribute to the pelagic sedimentation will be discussed from coccolithophorids, planktic foraminifers and pteropods (calcareous oozes) to diatoms, radiolarians and dinoflagellates (opal oozes). It outlines, in addition, the history of ancient pelagic sediment factories since the evolutionary invention of planktic life on Earth and discusses how the biosphere influenced the whole earth system through changes in ocean chemistry and how these changes, in turn, controlled the evolution of marine life.

Marine carbonate facies in response to climate and nutrient level: The upper carboniferous and permian of central spitsbergen (Svalbard)

SummaryCarbonate-dominated successions of the Gipsdalen and Tempelfjorden Groups from Svalbard record a significant shift from Photozoan to Heterozoan particle associations in neritic settings during the late Palaeozoic. During the Bashkirian, benthic particle associations which included photoautotrophs such as phylloid algae (Chloroforam Association) characterised shallow subtidal environments. Most depositional settings which endured siliciclastic terrestrial input exhibited poorly diversified associations dominated by brachiopods, bryozoans and siliceous sponges (Bryonoderm Association). During the Moscovian to Asselian, highly diversified associations typified by various calcareous green algae,Palaeoaplysina, Tubiphytes, fusulinids, smaller and encrusting foraminifers (Chloroforam Association) prevailed in carbonate sediments from supratidal to shallow subtidal environments. During the Sakmarian and Early Artinskian, oolitic carbonate sands (Chloroforam Association) typified intertidal flats, whereas shallow subtidal environments were occupied by moderately diversified associations with fusulinids, smaller foraminifers, echinoderms and bryozoans (Bryonoderm-extended Association) and poorly diversified associations with echinoderms, brachiopods and bryozoans (Bryonoderm Association). During the Late Artinskian to Kazanian, poorly diversified associations characterised by brachiopods, echinoderms and bryozoans (Bryonoderm Association), and sponge-dominated associations (Hyalosponge Association) reigned within siliceous carbonates of intertidal and shallow subtidal environments.This trend is interpreted as a result of climatic cooling and fluctuations of prevailing levels of trophic resources within shallow-water settings during the studied time period. While raised nutrient levels were restricted to near-shore settings during the Bashkirian, steady mesotrophic conditions arose from the Sakmarian onward and increased to late Permian times.

Chapter 17 Identification of Ancient Contourites: Problems and Palaeoceanographic Significance

Publisher Summary This chapter reviews problems associated with some of the case studies with which the body of evidence used in their interpretation as contourites is most persuasive such as Neogene contourites, Miura–Boso region, SE Japan; and Carbonate contourite drift, Oligocene palaeoslope, Cyprus. Some of the important common attributes from these studies, such as preservation, conditions of contourite deposits, and the paramount need for caution when trying to interpret ancient deep-water successions are discussed. The late -Cretaceous to early -Miocene Lefkara Formation is deposited over a newly formed oceanic crust of the Tethys Ocean. It forms a mostly continuous succession, up to 600m thick, and is relatively free from tectonic deformation. Distinct Santonian–Maastrichtian seismic units of the Late Cretaceous chalk in the Danish Basin based on seismic profiles in the Kattegat and Oresund areas are interpreted as contourites deposited in an epeiric sea. The Cenomanian–Danian Chalk Group in the North Sea and the Danish Basin are deposited in a relatively deep epeiric sea. Bottom-current-induced deposition occurred contemporaneously in different settings of the narrow oceanic passageways between the approaching continents of Gondwana and Laurussia. The areas affected are the southeastern Rhenish Sea shelf, which occupied the distal passive margin of Laurussia; the disintegrated northern continental margin of Gondwana, whose sedimentary record is now preserved in the Moroccan Meseta; and deep marginal plateaus of the Noric Terrane in the western part of the Prototethys.

Chapter 1 – Progress in Deep-Sea Sedimentology

Publisher Summary This chapter provides an overview of deep-sea sedimentology. The sediments in the deep-sea comprise of: (1) clastic particles derived from eroded rocks and sediments outcropping either on the emerged continents or previously deposited in a marine environment; (2) particles formed by volcanic eruptions; (3) particles formed by living organisms; and (4) particles formed by chemical precipitation of the elements contained in the salty sea water. Tools used for deep-sea sediment investigations are: geophysics, geotechnic tools, and sediment sampling. The deep-sea can be investigated by both indirect and direct measurements from a boat or a vessel. Multibeam echosounders allow measuring the bathymetry on a strip parallel to the boat track with a width of typically 120°–150°, to provide high-precision bathymetric maps. Some other tools used are side-scan sonar and seismic tools. Deep-sea current meters are systems anchored on the sea floor. Laboratory techniques for sedimentological studies of deep-sea sediments include a non-destructive analysis using core scanners. This allows a measurement of the sediment properties over the entire length of a core sample, including color reflectance and other physical properties geochemistry of the main chemical elements by X-ray fluorescence (XRF), and 3-D analysis of sedimentary structures.

Hemipelagic Advection and Periplatform Sedimentation

Abstract In areas close to continental margins, where siliciclastic supply is abundant, pelagic rain of biogenic materials is substantially diluted by clay- and silt-sized terrigenous components. These muds are known as hemipelagic sediments. In the vicinity of shallow-water carbonate platforms, in analogy, pelagic rain is diluted by neritic debris supplied from the carbonate-platform tops and margins to the adjacent deep-ocean water column. Those oozes are termed periplatform carbonates. In both cases, open-ocean materials and shelf- or platform-derived particles collectively rain down through the lower water column and settle onto the sediment. This chapter presents an overview of the large diversity of processes and principal factors that control hemipelagic advection and periplatform settling and determines the character and distribution of the resulting deep-sea sediments. River discharge, dust load, or sea ice and icebergs are the main sediment carriers, which supply sediment onto the shelves. There, complex processes of differential dispersal, bypassing, or resuspension and redeposition affect the sedimentary materials before they are finally transferred to the continental margins. Therefore, shelves may act as major filters as well as conduits for siliciclastic-sediment transfer into the deep sea. Off-shelf transport of carbonate-platform materials is mainly achieved by storms or wind- and tide-driven advection and can be temporarily forced by density cascading and geostrophic currents. Special attention is given to compositional variations in the shallow-water-derived materials since these mainly reflect changes in the source region or in the bypass area on the shelf. For the accumulation of both types of sediments, hemipelagic muds and periplatform oozes, the impact of sea-level fluctuations and climatic changes is very high and outlined in the discussion.

Geodynamic model of the northwestern Caribbean: scaled reconstruction of Late Cretaceous to Late Eocene plate boundary relocation in Cuba

Reviewing the local geological data of Cuba, its structural relations to Hispaniola and Jamaica as well as a comparison of prevalent plate tectonic models, allow for a refined Late Creta- ceous to Miocene tectonic reconstruction. The Cuban orogenic belt records subduction, volcanic arc formation and accretion along the pre-Eocene northwestern leading edge of the Caribbean plate. Geologic evidence points to a two-stage development with change in subduction polarity from a south- and southwest-dipping Cretaceous to a north-dipping Paleocene to Early Eocene subduction zone. During the Late Campanian, the Cretaceous arc collided with the North American continental margin. Ophiolites and parts of the Cretaceous volcanic arc are thrust onto the North American continental margin until the Late Eocene. After the initial Campanian collision, the Caribbean plate continued its relative northward movement. As a consequence, oceanic lithosphere of the back-arc area was emplaced on the top of the southern extension of the inactive arc. During the Danian, a new north-dipping subduction zone was established that consumed oceanic lithosphere of the Caribbean plate until the Middle Eocene. The arrival of thickened oceanic crust of the Caribbean Large Igneous Province stopped the subduction and the relative northward movement of the Caribbean plate. Subsequently, in the Middle Eocene the east-west striking Oriente transform fault system was formed which since then represents the northern boundary of the Caribbean plate.