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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Biostratigraphic results of foraminiferal studies for Site 397 indicate a probable Hauterivian-Barremian through BarremianAptian age for the Lower Cretaceous sedimentary section (Unit 5, Cores 52A-35A). Typical index species of the planktonic foraminifers include Hedbergella hoterivica, Hedbergella sigali, Calvihedbergella aff. simplex, and Globigerinelloides blowi. Important benthic species include Epistomina caracolla, Epistomina hechti, Epistomina cretosa, Epistomina ornata, Lenticulina nodosa, Lenticulina saxonica, Lenticulina praegaultina, Lenticulina heiermanni, Lenticulina matilatus, and Conorboides sp. Sedimentologic and ecologic data from the microfossils suggest prodelta shelf depth merging into upper bathyal environments. Benthic foraminifers (such as Quinqueloculina associated with ostracodes and small gastropods and pelecypods) may indicate a nearshore environment in front of a deltaic complex. Epistominids (such as Epistomina caracolla and the nodosariids such as Lenticulina, Dentalina, and Planularia) indicate an outer-shelf to upper bathyal environment. However, hedbergellids and a few radiolarian specimens suggest the epipelagic setting of an open-shelf water mass, and can be compared with Recent shelf pelagic biota. Paucity of fauna indicates neither stagnant bottom conditions (pelagic sapropel) nor oceanic depths below the calcite compensation depth (CCD). The barren character of the facies may indicate dilution by the sediments due to continuous terrigenous (cyclic sedimentation) input into the shelf basin. This in turn caused instability of the biophysiochemical conditions. Scarcity of the pelagic constituents in the sediment may also reflect low plankton productivity, possibly related to a restricted circulation due to the paleogeographic setting of the macroplates during the Early Cretaceous.

Lower Cretaceous Foraminiferal Biostratigraphy, Paleoecology, and Depositional Environment at DSDP Site 397, Leg 47A