نتایج جستجو برای: planktonic and benthic foraminifera

تعداد نتایج: 16831487  

2005
Andrea Dutton Kyger C Lohmann Mark Leckie

[1] Stable isotope and elemental measurements were conducted on foraminifera from a sequence of calcareous pelagic ooze at Ocean Drilling Program Site 1209 to document the thermal evolution of the North Pacific water column over Shatsky Rise and to address long-standing questions about the nature of oceanic circulation in the early Paleogene. A major change in seasonality and water column struc...

Journal: Geopersia 2016

A micropaleontological study has been carried out on the samples collected from the Sarv Abad section, the oldest and only known Jurassic sedimentary rocks cropping out in the Moghan area. Studied sequence consists of carbonates bounded at both base and top by clastic deposits. Studied carbonate deposits provide an assemblage of benthic foraminifera as well as calcareous algae. The stratigraphi...

Journal: :علوم 0

the gurpi formation, at the type section (nw of masjed-soleiman) and in sabze-kuh (sw of borujen) are lithologically subdivided into 8 and 11 units, respectively. the study of planktonic foraminifera resulted in recognition of 7 biozones in lali area and 4 biozones in sabzeh-kuh area. these biozones are compared to the most standard biozones defined in tethysian domain. biozones i (globotruncan...

Journal: Geopersia 2016
Farzaneh Barani Felix Schlagintweit, Koorosh Rashidi

The larger benthic foraminifera Gyroconulina columellifera Schroeder & Darmoian, 1977 (type-locality: Maastrichtian Aqra Formation of Iraq) is described for the first time from two sections of the Maastrichtian Tarbur Formation of the Zagros Fold-Thrust-Belt, SW Iran. New details on its wall microstructure are provided. The microfacies is represented by bioclastic wacke-/pack-/grainstones with ...

2009
D. Dissard G. Nehrke G. J. Reichart

Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future...

2010
Edward A. Boyle Jeffrey Nicholas Berry

The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate was developed, employing a high-resolution inductively coupled plasma-mass spectrometer. The sulfur measurements, expressed as sulfur-to-calcium (S/Ca) ratios in the foram...

2017
Tamar Guy-Haim Orit Hyams-Kaphzan Erez Yeruham Ahuva Almogi-Labin James T. Carlton Leon H. Charney

Many species of Indo-Pacific holobenthic foraminifera have been introduced and successfully established sustainable populations in the Mediterranean Sea over the past few decades. However, known natural and anthropogenic vectors do not explain how these species were introduced long distances from their origin. We present evidence for a novel marine bioinvasion vector explaining this long-distan...

2010
E. Ufkes D. Kroon

Here we study the carbonate dissolution history of the deep SE Atlantic as evidenced in proxy records in Core T89-40 from the Walvis Ridge, spanning the last 1.1 million years. All dissolution proxy records (fragmentation index, ratio of planktonic and benthic foraminifera, sand fraction and number of planktonic foraminifera per gram sediment) show similar patterns, unique events, and these pro...

2000
Hilary A. Paul James C. Zachos Benjamin P. Flower Aradhna Tripati

To assess the influence of orbital-scale variations on late Oligocene to early Miocene climate and ocean chemistry, high-resolution (~5 kyr) benthic foraminiferal carbon and oxygen isotope and percent coarse fraction time series were constructed for Ocean Drilling Program site 929 on Ceara Rise in the western equatorial Atlantic. These time series exhibit pervasive lowto high-frequency variabil...

Journal: :Science 2005
Laura F Robinson Jess F Adkins Lloyd D Keigwin John Southon Diego P Fernandez S-L Wang Daniel S Scheirer

We present a detailed history of glacial to Holocene radiocarbon in the deep western North Atlantic from deep-sea corals and paired benthic-planktonic foraminifera. The deglaciation is marked by switches between radiocarbon-enriched and -depleted waters, leading to large radiocarbon gradients in the water column. These changes played an important role in modulating atmospheric radiocarbon. The ...

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