Elevated primary productivity of calcareous nannoplankton associated with ocean anoxic event 1b during the Aptian/Albian transition (Early Cretaceous)

Calcareous Nannoplankton Response to Late Albian Oceanic Anoxic Event 1d in the western North Atlantic

Comment on "Calcareous nannoplankton response to surface-water acidification around Oceanic Anoxic Event 1a".

Erba et al. (Reports, 23 July 2010, p. 428) attributed calcareous nannofossil morphology and assemblage changes across Cretaceous Oceanic Anoxic Event 1a to the effects of surface ocean acidification. We argue that the quality of carbonate preservation in these sequences, the unsupported assumptions of the biotic response to acidity, and the absence of independent proxy estimates for ocean pH o...

The importance of diazotrophic cyanobacteria as primary producers during Cretaceous Oceanic Anoxic Event 2

In Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca. 94 Ma), nitrogen isotopic compositions of bulk sediments are mostly in a narrow range from –2.7 to –0.7‰. We also determined molecular distribution and nitrogen isotopic compositions of geoporphyrins extracted from the black shale. The nitrogen isotopic compositions of C32 Ni deoxophylloerythroetiopo...

Massive expansion of marine archaea during a mid-Cretaceous oceanic anoxic event.

Biogeochemical and stable carbon isotopic analysis of black-shale sequences deposited during an Albian oceanic anoxic event (approximately 112 million years ago) indicate that up to 80 weight percent of sedimentary organic carbon is derived from marine, nonthermophilic archaea. The carbon-13 content of archaeal molecular fossils indicates that these archaea were living chemoautotrophically. The...

Record bio-events and study the distribution of calcareous nannofossils in Cretaceous-Paleogene sediments, Neo-Tethys Ocean realm

In the present study, the sediments of the Gurpi Formation in the Jafarabad section located in the southeast of Ilam were examined from the point of view of calcareous calcareous nannofossils. The sediments of the upper part of Gurpi Formation with a thickness of about 42 m are composed of limy marl sediments. In this study, 34 species belonging to 22 genera from the group of calcareous nannopl...