Consulta: creatorFacets:"Weis, D"
Registros recuperados: 5
Data/hora: 03/06/2024 00:45:08

A bimodal alkalic shield volcano on Skiff Bank: Its place in the evolution of the Kerguelen Plateau
Provedor de dados: 5
Autores: Kieffer, B; Arndt, Nt; Weis, D.
A bimodal volcanic sequence of 230 m thickness on Skiff Bank, a western salient of the northern Kerguelen Plateau, was drilled during ODP Leg 183. The sequence comprises three main units: a mafic unit of trachybasalt flows sandwiched between two units of trachytic or rhyolitic flows and volcaniclastic rocks. Although interpretation is complicated by moderate to strong alteration of the rocks, their original chemical character can be established using the least mobile major and trace elements (Al, Th, high field strength elements and rare earth elements). High concentrations of alkalis and incompatible trace elements indicate that both mafic and felsic rocks are alkalic. The felsic rocks may have been derived by partial melting of mafic rocks, followed by...
Tipo: Text
Palavras-chave: Ocean Drilling Program; Kerguelen Plateau; Skiff Bank.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33406/31863.pdf

Constraining the components of the Kerguelen mantle plume: A Hf-Pb-Sr-Nd isotopic study of picrites and high-MgO basalts from the Kerguelen Archipelago
Provedor de dados: 5
Autores: Doucet, S; Scoates, Js; Weis, D; Giret, A.
We report geochemical and Hf-Pb-Sr-Nd isotopic analyses of a suite of picrites and associated high-MgO volcanic rocks (6-17 wt.% MgO) from the Kerguelen Archipelago, which are rare compared to other oceanic islands, to better constrain the nature and the origin of components present in the Kerguelen mantle plume source. The Sr and Nd isotopic compositions of the transitional to mildly alkalic picrites and high-MgO basalts closely match those of the 24 Ma mildly alkalic basalts from the Courbet Peninsula, whose compositions are considered to reflect the present geochemical expression of the enriched component of the Kerguelen mantle plume. However, linear trends in Pb isotopic compositions in the studied samples reflect involvement of a component with lower...
Tipo: Text
Palavras-chave: Kerguelen Archipelago; Picrites; Hf-Pb-Sr-Nd isotopes; Mantle plume components; Composition of the mantle; Radiogenic isotope geochemistry; Major and trace element geochemistry; Igneous petrology; Indian Ocean.
Ano: 2005
URL: https://archimer.ifremer.fr/doc/00230/34086/32519.pdf

Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern
Provedor de dados: 5
Autores: Fagel, N; Hillaire-marcel, C; Humblet, M; Brasseur, R; Weis, D; Stevenson, R.
Nd and Pb isotopes were measured on the fine fraction of one sediment core drilled off southern Greenland. This work aims to reconstruct the evolution of deep circulation patterns in the North Atlantic during the Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan-African and Variscan crusts, and the Mid-Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2-6.5 ka) is composed of material derived from the North American shield and from a "young'' crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the...
Tipo: Text
Palavras-chave: Clay-size fraction; Sedimentary mixings; Deep circulation; Nd and Pb isotopes; North Atlantic; Labrador Sea.
Ano: 2004
URL: https://archimer.ifremer.fr/doc/00226/33731/32199.pdf

Trace of the Kerguelen mantle plume: Evidence from seamounts between the Kerguelen Archipelago and Heard Island, Indian Ocean
Provedor de dados: 5
Autores: Weis, D; Frey, Fa; Schlich, R; Schaming, M; Montigny, R; Damasceno, D; Mattielli, N; Nicolaysen, Ke; Scoates, Js.
The gravity and bathymetric highs on the Kerguelen Plateau in the southern Indian Ocean between the Kerguelen Archipelago and Heard Island are seamounts formed of Miocene alkalic basalts similar to those found on the islands. Dredging during the Kerimis survey cruise recovered &gt;1 ton of mostly basaltic rocks. One of the dredges (D6) yielded a large volume of in situ alkalic picritic pillow basalts, the first picritic lavas recovered that are related to the Kerguelen plume. K-Ar and Ar-40-Ar-39 ages are between 18 and 21 Ma for all but one sample, and these ages are only slightly younger than the main phase of volcanism on the archipelago. The dredged lavas form three distinct groups based on chemical and isotopic compositions. Incompatible element...
Tipo: Text
Palavras-chave: Kerguelen; Trace elements; Isotopes; Mantle plume; Hot spot track; Picrites; Geochemistry; 1025 Geochemistry : Composition of the mantle; 1040 Geochemistry : Isotopic composition/chemistry; 1065 Geochemistry : Trace elements (3670).
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33407/31856.pdf

Anthropogenic contamination of bivalves revealed by Cd isotopes
Provedor de dados: 5
Autores: Shiel, A; Orians, K; Cossa, Daniel; Weis, D.
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3948.pdf