English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

High-resolution, digital, single-channel seismic profiles collected aboard the JOIDES Resolution provide a regional stratigraphic context for seven drill sites (881-887) from four locations in the North Pacific. The seismic thickness of the sedimentary section varied from > 1 -second two-way traveltime at the Detroit Seamount in the northern Emperor Seamount Chain to <O.l s TWT at the abyssal seafloor Sites 885/886 near the Chinook Trough. The 1-ms data were processed with SIOSEIS receiving mute, deconvolution, gain recovery, and time-varying filters to enhance reflections and correlate to synthetic seismograms generated from downhole logs and physical properties data. The reflection sequence at each site was correlated to the lithostratigraphy and impedance contrasts caused by density and velocity variations with an average mistie of about 3 m over several hundred meters. A three-part seismic character was recognized at all locations. The uppermost glacialand ash-influenced Pliocene-Pleistocene section had high frequencies and spatial variability characteristic of enhanced hemipelagic sedimentation. Miocene diatom oozes dominate the draping and acoustically transparent middle section. Alternating intervals with discontinuous high-frequency reflections and more widely correlated moderate-amplitude reflections appear as the high cut and gain are increased. These correspond to alternating intervals of greater and lesser variability in the physical properties. The basal sedimentary section tends to be Paleogene and is characterized by moderate to strong reflections that lap and dip with respect to local basement relief and show evidence of bottom-current influence and downslope slumping and reworking. These near-basement lithologies include claystone, chalk, altered ash, and sediment-sill complexes. The seismic stratigraphy at Site 881 on the Zenkevich Rise has folds, unconformities, and faults that cut to the top of the section and show tectonic reactivation on the approach to the Kurile Trench. High-latitude seamount platforms like those sampled at the Detroit Seamount sites (882-884) and at Site 887 on the Murray Seamount show great thicknesses and fast rates of middle Tertiary sedimentation. From the high-resolution seismic stratigraphy, the middle Tertiary biosiliceous ooze offers the best prospect for investigations of paleoclimatic and oceanography cyclicity.

Seismic Stratigraphy of Cenozoic Sediments from North Pacific Seamount Platform and Deep-Sea Sites, Leg 145