High-precision dating of the metamorphic sole ophiolites can provide insight into tectonic evolution and subduction zone processes. To understand initiation beneath a young, well-preserved, well-characterized ophiolite, we performed coupled zircon laser-ablation inductively mass spectrometry (LA-ICP-MS) trace element analyses high-precision isotope dilution-thermal ionization (ID-TIMS) U-Pb on ...

The Mauritanian Tasiast unit in the Southwestern Reguibat Archean Shield (North of West African craton = WAC) consists mainly gneiss dated between 3.07 and 2.91 Ga. We present new field petrographic observations combined with whole-rock geochemical data on gneisses to understand their petrogenesis, tectonic setting, evolution continental crust WAC. These provide firm evidence two distinct ortho...

Neutron activation analysis was employed in a survey of weathering abilities of rock surface microorganisms. A yeast isolated from an amphibolite of a megalithic grave was found actively to concentrate, in media and in or on cells, iron and other elements when grown in the presence of ground rock. This was demonstrated by comparing a spectrum of neutron-activated amphibolite powder (particle si...

Structural field relations, petrologic and geochemical studies, and radiometric age aualysis of metamorphic rocks at the base of the Brooks Range ophiolite provide a record of the time, tectonic setting, and initial conditions of ophiolite emplacement during the Middle Jurassic western Brookian orogeny. The metamorphic sole of the Misheguk, Siniktanneyak, and Avan Hills ophiolite bodies is tran...

This paper is a complement to the Tectonometamorphic Map of the Canadian Shield, and contains a brief description of the metamorphic history of Proterozoic orogenic belts and rock sequences in the Canadian Shield in Ontario, with a focus on rocks of the Southern and Grenville provinces. Metamorphism in the Southern Province has generally been attributed to the Penokean orogeny (~1879–1820 Ma), ...

New mapping, geochronology, and geochemistry of the supracrustal enclave and associated orthogneisses at Akilia, West Greenland, support a >3825 6 Ma age for the sequence and a chemical sedimentary origin for the controversial Fe-rich quartz-pyroxene gneisses. Lithologies of the enclave comprise laterally continuous, mappable units of mafic amphibolite, ultramafic rocks, and two Fe-rich quartzp...