Uppermost Maastrichtian Research Articles

Calcareous nannofossils and clastic sediments at the Cretaceous-Tertiary boundary, northeastern Mexico

Research Article| March 01, 1996 Calcareous nannofossils and clastic sediments at the Cretaceous-Tertiary boundary, northeastern Mexico James J. Pospichal James J. Pospichal 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Search for other works by this author on: GSW Google Scholar Author and Article Information James J. Pospichal 1Department of Geology, Florida State University, Tallahassee, Florida 32306 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1996) 24 (3): 255–258. https://doi.org/10.1130/0091-7613(1996)024<0255:CNACSA>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation James J. Pospichal; Calcareous nannofossils and clastic sediments at the Cretaceous-Tertiary boundary, northeastern Mexico. Geology 1996;; 24 (3): 255–258. doi: https://doi.org/10.1130/0091-7613(1996)024<0255:CNACSA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A quantitative analysis of calcareous nannofossil assemblages on the Cretaceous-Tertiary (K-T) boundary of the Mimbral and Mulato outcrops of northeast Mexico indicates that the sections are biostratigraphically complete across the boundary and that there is a prominent spherule-bearing clastic unit located precisely at the K-T boundary. The sections consist of uppermost Maastrichtian (Micula prinsii Zone) marly limestones of the Mendez Formation and marlstones of the lower Paleocene (Zone NP1) Velasco Formation separated by a distinct, 1–3-m-thick sandstone unit that has a basal spherule-bearing layer. The origin of this clastic unit and the time of deposition relative to the K-T mass extinctions have been the subjects of much controversy. Some workers attribute this unit to rapid tsunami-induced deposition triggered by the nearby Chicxulub impact, and others consider it a turbidite deposited at some time prior to the K-T mass extinctions. Cretaceous nannofossils abruptly decrease in abundance at the base of the spherule bed and only rare to few reworked specimens are present in the clastic unit and in the basal Velasco Formation. Survivors and Tertiary species are common above the clastic unit. Cretaceous nannoplankton show no evidence of recovery after deposition of the clastic unit, which indicates that extinctions probably occurred correlative with the deposition of the clastic unit and in association with the Chicxulub impact. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Uppermost Maastrichtian ammonites from the uninterrupted Upper Cretaceous – Paleogene section at Bjala (East Bulgaria)

Uppermost Maastrichtian ammonites from the uninterrupted Upper Cretaceous – Paleogene section at Bjala (East Bulgaria)

&amp;lt;i&amp;gt;Krausella minuta&amp;lt;/i&amp;gt;, a nomen nudum in ostracodology, and three new species of &amp;lt;i&amp;gt;Cardobairdia&amp;lt;/i&amp;gt; Bold, 1960 from the Campanian of Belgium and the Cenomanian of southern England

Abstract. Van Veen (1936b) found the ostracod species Krausella minuta Triebel, in deposits of the uppermost Maastrichtian from the Valley of the Jeker, South Limburg, The Netherlands. Investigation has shown that Triebel never published any data on this species, so the name Krausella minuta has to be rejected, being a nomen nudum.In the boreholes of Kallo (27 E 148) and Knokke (11 E 138), in the northwestern part of Belgium, a related, yet undescribed species occurs, for which the name Cardobairdia triebeli sp. nov. is proposed. This taxon was found in deposits of mainly Lower Campanian age. Another new species, Cardobairdia rectimarginata, is described from the Campanian in the Knokke Borehole.The specimens of Cardobairdia minuta from the Cenomanian from southern England belong to a new species, defined here as C. cenomanensis.

Large heteromorph ammonites from the Upper Cretaceous of Seymour Island, Antarctica

Two species of the heteromorph ammonite genus Diplomoceras Hyatt are described from the Upper Cretaceous of the James Ross–Seymour Islands area, Antarctica. The late Campanian–early Maastrichtian D. lambi Spath has a relatively high rib density, whereas D. maximum n. sp. has a lower rib density and is known only from the uppermost Maastrichtian of the Lopez de Bertodano Formation on Seymour Island. Both species attain an exceptionally large size with the body chamber of D. maximum n. sp. attaining a length in excess of one meter. The structure of the shell wall in Diplomoceras is characterized by the thickening of the nacreous layer below the ribs. The shell thickening results in an inner flat surface and a smooth phragmocone. Reconstruction of the shell suggests at least four parallel shafts and three U-connectives. Estimates of the total density, center of buoyancy, and center of mass in this reconstructed shell indicate a slightly positive buoyant shell with a relatively unstable floating position.

Dinoflagellate biostratigraphy of the Maastrichtian to Danian interval in the U.S. geological survey Albany core, Georgia, U.S.A.

Abstract Dinoflagellate assemblages are used to delineate three intervals within the upper Ripley Formation and Providence Sand (Maastrichtian), and the lower Clayton Formation (Danian) in the U.S. Geological Survey Albany core, located near Albany, Georgia. Interval A is interpreted as early Maastrichtian in age, interval B is late Maastrichtian, and interval C is early Danian, based on comparisons with dinoflagellate cyst zonations from the type Maastrichtian and Danian regions. Comparison with a dinoflagellate cyst zonation from the Maastrichtian Severn Formation of Maryland indicates that the lower Severn is correlative with the upper Ripley and lower Providence, and that the upper Severn is correlative with the upper Providence. The Cretaceous‐Tertiary boundary is marked by a minor turnover in organic‐walled phytoplankton species. Some of the uppermost Maastrichtian and lowest Danian may be missing from the section. Variations in the relative abundances of Spiniferites and Manumiella see‐landica indicate a shallowing of the marine environment through the Maastrichtian. The species Manumiella druggii is considered to be a junior synonym of Manumiella seelandica.

Campanian to Maastrichtian Pollen Biostratigraphy and Floral Turnover Rates, Colville River Region, North Slope of Alaska: ABSTRACT

This study is based on occurrence data for 104 angiosperm pollen taxa from 83 pollen-bearing outcrop and core samples taken along the Colville River and stratigraphically distributed from the base of the Sentinel Hill Member of the Schrader Bluff Formation to the top of the Cretaceous section. Many of the pollen taxa are highly useful for intraregional correlations because they have remarkably short stratigraphic ranges and are consistently present within these ranges. Important similarities are present between North Slope pollen assemblages and those of western Canada, Siberia, and China. The Campanian-Maastrichtian boundary is approximately marked by the range bases of Wodehouseia edmontonicola and Senipites drummhellerensis and is nearly as far south (downsection) as Sentinel Hill core test 1. Based on pollen correlations with Alberta, the marine beds at Ocean Point are probably within the middle part of the Maastrichtian, and strata north of Ocean Point that contain Aquilapollenites conatus are uppermost Maastrichtian. Thus, if the Cretaceous-Tertiary boundary in the study area is represented by an unconformity as their data suggest, the lowermost Paleocene is missing, not the uppermost Cretaceous. Maximum diversities of species of the stratigraphically significant Triprojectacites and Expressipollis groups are in the upper Campanian. Major turnovers of angiospermmore » taxa occurred late in the Campanian and in the Maastrichtian, but high rates of first appearances coincided with high rates of last appearances. Thus, once a fairly high overall angiosperm diversity was established in the middle(.) Campanian, the diversity remained relatively constant until at or near the end of the Maastrichtian.« less

The genus Kassabiana Salaj, 1983, from the uppermost Maastrichtian of northeastern Tunisia

The genus Kassabiana, established by Salaj as a member of the family Globotruncanidae Brotzen, 1942, is discussed in detail. In addition to a detailed diagnosis and remarks, the second member of the genus, Kassabiana falsocalcarata trigonocamerata subsp. nov., found in the uppermost Maastrichtian at Enfidaville, northeastern Tunisia, is presented.

The Walvis Ridge transect, Deep Sea Drilling Project Leg 74: The geologic evolution of an oceanic plateau in the south Atlantic Ocean

Five sites were drilled along a transect of the Walvis Ridge. The basement rocks range in age from 69 to 71 m.y., and the deeper sites are slightly younger, in agreement with the sea-floor–spreading magnetic lineations. Geophysical and petrological evidence indicates that the Walvis Ridge was formed at a mid-ocean ridge at anomalously shallow elevations. The basement complex, associated with the relatively smooth acoustic basement in the area, consists of pillowed basalt and massive flows alternating with nannofossil chalk and limestone that contain a significant volcanogenic component. Basalts are quartz tholeiites at the ridge crest and olivine tholeiites downslope. The sediment sections are dominated by carbonate oozes and chalks with volcanogenic material common in the lower parts of the sediment columns. The volcanogenic sediments probably were derived from sources on the Walvis Ridge. Paleodepth estimates based on the benthic fauna are consistent with a normal crustal-cooling rate of subsidence of the Walvis Ridge. The shoalest site in the transect sank below sea level in the late Paleocene, and benthic fauna suggest a rapid sea-level lowering in the mid-Oligocene. Average accumulation rates during the Cenozoic indicate three peaks in the rate of supply of carbonate to the sea floor, that is, early Pliocene, late middle Miocene, and late Paleocene to early Eocene. Carbonate accumulation rates for the rest of the Cenozoic averaged 1 g/cm 2 /10 3 yr. Dissolution had a marked effect on sediment accumulation in the deeper sites, particularly during the late Miocene, Oligocene, and middle to late Eocene. Changes in the rates of accumulation as a function of depth demonstrate that the upper part of the water column had a greater degree of undersaturation with respect to carbonate during times of high productivity. Even when the calcium carbonate compensation depth (CCD) was below 4,400 m, a significant amount of carbonate was dissolved at the shallower sites. The flora and fauna of the Walvis Ridge are temperate in nature. Warmer-water faunas are found in the uppermost Maastrichtian and lower Eocene sediments, with cooler-water faunas present in the lower Paleocene, Oligocene, and middle Miocene. The boreal elements of the lower Pliocene are replaced by more temperate forms in the middle Pliocene. The Cretaceous-Tertiary boundary was recovered in four sites drilled, with the sediments containing well-preserved nannofossils but poorly preserved foraminifera.

Studies on the Blood of Dogs: III. —Hæmatological Findings in some Physiological States—(a) Pregnancy; (b) Post-Partum and Lactation

An ichthyofauna recovered from the López de Bertodano Formation at Units 9 (uppermost Maastrichtian) and 10 (lowermost Danian) and the Sobral Formation (Danian), in Marambio (Seymour) Island in the James Ross Basin is described and analyzed herein. A review of previously described taxa based on the new material and several new fish records for the López de Bertodano Formation is provided, including the youngest record of Enchodus and the first Cretaceous evidence of Pachycormiformes. We also identify the first Paleocene fishes for the continent. The new information and the reinterpretation of previous Cretaceous records show that there was no decline in fish diversity until the Cretaceous–Paleogene (K/Pg) boundary in the area and extinction event appears to have been rapid. Finally, we find that the distribution of some chondrichthyans and teleosts in the James Ross Basin appears to be climatically determined.