نتایج جستجو برای: sediment geochemistry

تعداد نتایج: 42812  

2013
David Z. Piper Michael Bau

The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an elementby-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived b...

2009
KEVIN KIERNAN DAMIAN B. GORE DAVID FINK DUANNE A. WHITE ANNE MCCONNELL INGVAR A. SIGURDSSON

In situ cosmogenic Be exposure dating, radiocarbon determinations, salt and sediment geochemistry, and rock weathering observations indicate that parts of Larsemann Hills, East Antarctica have been subaerially exposed throughout much of the last glacial cycle, with the last glaciation occurring prior to 100 ka BP. Salt-enhanced subaerial weathering, coupled with a paucity of glacial erratics, m...

Journal: :Geosciences 2021

The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group elements may suffer during a depositional cycle. In present investigation, we and XRD mineralogy set sand mud fluvial to evaluate ability REE parameters tracing, changes associated with weathering sorting. analyzed were generated subtropical dra...

Journal: :The Journal of Geology 2022

Elemental geochemistry, Nd isotopes, clay minerals, and U-Pb zircon ages integrated by petrographic heavy-mineral data offer a multiproxy panorama of mud sand composition across the Zambezi sediment-routing system. Detrital geochronology highlights four major episodes crustal growth in southern Africa: Irumide predominate over Pan-African, Eburnean, Neoarchean ages. Smectite, dominant generated...

2015
Tan T. Nguyen Bjarne Landfald

Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities...

2016
Donato Giovannelli Giuseppe d'Errico Federica Fiorentino Daniele Fattorini Francesco Regoli Lorenzo Angeletti Tatjana Bakran-Petricioli Costantino Vetriani Mustafa Yücel Marco Taviani Elena Manini

Pockmarks are crater-like depression on the seafloor associated with hydrocarbon ascent through muddy sediments in continental shelves around the world. In this study, we examine the diversity and distribution of benthic microbial communities at shallow-water pockmarks adjacent to the Middle Adriatic Ridge. We integrate microbial diversity data with characterization of local hydrocarbons concen...

2009
C. Hensen

Submarine mud volcanism represents an important pathway for methane from deeper reservoirs to the surface, where it enters the benthic carbon cycle. To quantify overall methane release from the Captain Arutyunov mud volcano (CAMV) and to assess the contribution of macrobenthic seep organisms to the regulation of the benthic methane flux, we linked water column methane concentrations, seabed met...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Steffen Leth Jorgensen Bjarte Hannisdal Anders Lanzén Tamara Baumberger Kristin Flesland Rita Fonseca Lise Ovreås Ida H Steen Ingunn H Thorseth Rolf B Pedersen Christa Schleper

Microbial communities and their associated metabolic activity in marine sediments have a profound impact on global biogeochemical cycles. Their composition and structure are attributed to geochemical and physical factors, but finding direct correlations has remained a challenge. Here we show a significant statistical relationship between variation in geochemical composition and prokaryotic comm...

2016
Felix J. Elling Cornelia Spiegel Solveig Estrada Donald W. Davis Lutz Reinhardt Friedhelm Henjes-Kunst Niklas Allroggen Reiner Dohrmann Karsten Piepjohn Frank Lisker

The Paleocene was a time of transition for the Arctic, with magmatic activity of the High Arctic Large Igneous Province (HALIP) giving way to magmatism of the North Atlantic Large Igneous Province in connection to plate tectonic changes in the Arctic and North Atlantic. In this study we investigate the Paleocene magmatic record and sediment pathways of the Basilika Formation exposed in the Cent...

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