Reflector "Pc" a prominent feature in the Maud Rise sediment sequence (eastern Weddell Sea); occurrence, regional distribution and implications to silica diagenesis

Author(s): Bohrmann, Gerhard; Spiess, Volkhard; Hinze, Heinrich; Kuhn, Gerhard
Author Affiliation(s): Primary:
Alfred-Wegener-Inst. Polar- und Meeresforsch., Bremerhaven, Federal Republic of Germany
Other:
Univ. Bremen, Federal Republic of Germany
Volume Title: Marine Geology
Source: Marine Geology, 106(1-2), p.69-87. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. Alfred Wegener Inst. Polar and Mar. Res., Contrib. No. 486; Spec. Res. Proj. SFB 261, Publ. No. 43. 29 refs.; illus. incl. sects., sketch maps
Summary: Condensed pelagic deposits characterize the uppermost sediment sequence of the Maud Rise in the eastern Weddell Sea. The comparison of subbottom profiling data with the sediments drilled at two ODP sites shows that Lithologic Unit Ib deposited during late Miocene to late Pliocene times is generally characterized by acoustic transparency. A prominent reflector with strongly increased amplitude (called Reflector "Pc") occurs within this mainly homogeneous diatom ooze unit and is correlated with the porcellanite horizon found at ODP Site 689. As evidenced by sediment findings, Reflector "Pc" marks a distinct stratigraphic layer of early Pliocene age. The development of the Reflector "Pc" and its amplitude of reflection in the echosounding records is most likely caused by the silica cementation of porcellanite within this layer. In large areas of the central Maud Rise, a patchy but also continuous distribution of Reflector "Pc" was found. On average Reflector "Pc" is detected around 11 and 12 m below seafloor, but depth occurrence is highly variable within the range of 8 m to more than 18 m. The apparent amplitude of Reflector "Pc" is higher in those areas where the diatom ooze Unit Ib reaches greater thicknesses, which may be caused by local enhanced tectonic subsidence. In general a good correlation of Reflector "Pc" amplitude and thickness of lithologic Unit Ib is observed. (Auth. mod.)
Year of Publication: 1992
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 12 Stratigraphy, Historical Geology and Paleoecology; 20 Geophysics, Applied; Acoustical methods; Algae; Antarctic Ocean; Bathymetry; Cementation; Cenozoic; Clastic rocks; Clastic sediments; Correlation; Diagenesis; Diatoms; Echo sounding; Foraminifera; Geophysical methods; Geophysical surveys; Invertebrata; Leg 113; Marine sediments; Maud Rise; Microfossils; Neogene; ODP Site 690; Ocean Drilling Program; Ooze; Pelagic sedimentation; Plantae; Pliocene; Porcellanite; Protista; Radiolaria; Reflection; Sedimentary rocks; Sedimentation; Sediments; Seismic stratigraphy; Silica; Southern Ocean; Stratigraphic units; Stratigraphy; Surveys; Tertiary; Thickness; Weddell Sea
Coordinates: S653200 S640000 E0040000 E0000000
Record ID: 1992021831
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from the Antarctic Bibliography, United States