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

Cretaceous sediments were recovered at five sites during Leg 39 in the western Atlantic. Only two sites, Site 356 on the Sào Paulo Plateau and Site 357 on the Rio Grande Rise, contained rich sequences of planktonic foraminifers allowing the recognition of biostratigraphic zones from the upper Albian through the Maestrichtian. Late Albian: Site 356 was closed to the North Atlantic, but opened intermittently to bottom and surface waters from the south. Both the planktonic and benthic foraminifer faunas are austral in character; there are no rotaliporids. The bottom depth here is estimated at around 1000 meters at this time. The late Albian northsouth communication postulated by Reyment (1969) was not indicated here in the foraminifer faunas. There is a hiatus from the latest Albian through the Cenomanian. However, the presence of reworked rotaliporids highpr in this section demonstrates the former presence of open marine deposition during the middle Cenomanian. Rotaliporids, a Tethyan group, indicate either a minor climatic change or free surface connection between the North and South Atlantic in the middle Cenomanian. Middle-late Turonian: The sediments at Site 356 are sapropelic and are preserved during regressive sea level stands. The early and latest Turonian are times of transgression in the South Atlantic and sediments of that age are missing at this site. Late Turonian-early Coniacian: There is a hiatus at the Turonian/Coniacian boundary including most of the late Turonian. Coniacian sediments are sapropelic, and the faunas contain Tethyan species evidencing the establishment of a permanent North-South connection by this time. The sapropels terminate at the top of the Coniacian section. Santonian: This is a period of transgressions and extensive reworking of material both at Site 356 and at the oldest levels recovered at Site 357. Inoceramus is found abundantly in the deep sediments of these sites, estimated to represent bathyal depths. There are large amounts of Coniacian material reworked into the Santonian at Site 357; and much early Santonian reworked into later Santonian, making biostratigraphic zonation very difficult. Santonian-Campanian: This is a major period of dissolution on the Rio Grande Rise (Site 357), which is not, however, found at the nearby Site 356. Faunas at Site 357 look as if they had been deposited near the CCD, although the site is estimated to have lain at bathyal depths. The nearby Leg 3, Site 21, lacks these dissolved faunas, suggesting either different sinking histories for these two segments of the Rio Grande Rise, or unusual bottom conditions at Site 357. Campanian-Maestrichtian: A major period of dissolution and sometimes reducing conditions is indicated at Sites 354, 355, 356, 357, 358, and at Sites 13 and 144 from Legs 3 and 14, respectively. Site 355 and later Site 358, both deep basinal sites, evolved at this time in a near-ridge position. Maestrichtian: Site 355 sank permanently below the paleo CCD by the end of the Maestrichtian. Site 358, on the other hand, apparently sank from above the paleo foraminifer lysocline intersecting either the lysocline or the CCD throughout the Maestrichtian. Improved preservation characterizes both the shallower Sites

Cretaceous Planktonic ForaminifersDSDP Leg 39 (South Atlantic)

Cretaceous Planktonic ForaminifersDSDP Leg 39 (South Atlantic)