Results 81 to 90 of about 15,483 (211)

Investigation of Archean gamma-ray fingerprint: Methodology and tectonic application in central Brazil

Journal of the Geological Survey of Brazil
Gamma-ray spectrometric responses of Archean rocks were studied in order to define a characteristic signature for these rocks. As the half-life of the most frequent Thorium isotope (232Th – half life of 14.05 Ga) is more than 3 times longer relative to ...
Marcus Flavio Nogueira Chiarini, Loiane Gomes de Moraes, Elton Luiz Dantas, Reinhardt Adolfo Fuck, Elias Prado, Raphael Teixeira Corrêa, Jaime Scandolara, Antônio Frasca, Joseneusa Rodrigues, Andre Menezes Saboia   +9 more
doaj   +1 more source

Hf-Nd Isotopes in Archean Marine Chemical Sediments: Implications for the Geodynamical History of Early Earth and Its Impact on Earliest Marine Habitats

Geosciences, 2018
The Hf-Nd isotope systems are coupled in magmatic systems, but incongruent Hf weathering (‘zircon effect’) of the continental crust leads to a decoupling of the Hf-Nd isotope systems in low-temperature environments during weathering and erosion processes.
Sebastian Viehmann
doaj   +1 more source

Geochemistry of Archean anorthosite-bearing layered intrusions

The geochemistry of Archean anorthosite-bearing layered intrusions has major implications for the thermal and chemical state of the Archean crust/mantle system, as originally posited by Bowen (1917) as “the anorthosite problem” and expanded on by Ashwal (
Yang, Xue-Ming, Polat, Ali, Sotiriou, Paul, Windley, Brian F., Kusky, Tim, Frei, Robert   +5 more
core   +1 more source

Geological and isotopic characteristics of granites from the Western Pernambuco-Alagoas Domain: implications for the crustal evolution of the Neoproterozoic Borborema Province

Brazilian Journal of Geology
The Western Pernambuco-Alagoas Domain is a complex tectonic domain of the Southern part of the Neoproterozoic Borborema Province. It borders the Northern margin of São Francisco Craton. U-Pb and Sm-Nd data discussed in this work show that, in the Western
Rodrigo Fabiano da Cruz, Márcio Martins Pimentel, Ana Cláudia de Aguiar Accioly, Joseneusa Brilhante Rodrigues   +3 more
doaj   +1 more source

Potassium Isotope Evidence for Origin of Archean TTG Rocks From Seawater‐Hydrothermally Altered Oceanic Crust

Geochemistry, Geophysics, Geosystems
Tonalite‐trondhjemite‐granodiorite (TTG) rocks constitute a crucial part of the Archean continental crust, yet their origins remain contentious. It is critical to decipher their source nature and hydration mechanism.
D.‐Y. Xiong, X.‐L. Wang, W. Li, Y.‐F. Zheng, C. R. Anhaeusser, A. Hofmann, D. Wang, J.‐Y. Li   +7 more
doaj   +1 more source

Archean granitoids of the Aravalli Craton, northwest India

, 2020
Table 1: Major (wt%) and trace element (ppm) data of Archean granitoids of the Aravalli Craton, NW India; Table 2: Nd-isotope data of Archean granitoids of the Aravalli Craton, NW ...
Md Sayad Rahaman (8422398), Rajneesh Bhutani (5844521), M. Satyanarayanan (8422401), Iftikhar Ahmad (2793085), M.A.E. Mondal (8422395)   +4 more
core   +1 more source

Nitrogen Isotopic Composition and Density of the Archean Atmosphere [PDF]

, 2013
International audienceUnderstanding the atmosphere's composition during the Archean eon is a fundamental issue to unravel ancient environmental conditions. We show from the analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0-3.5 Ga
Burgess, Ray, Philippot, Pascal, Burgess, Ray; id_orcid, Pujol, Magali, Marty, Bernard, Zimmermann, Laurent   +5 more
core   +1 more source

PALEOARCHEAN MAFIC ROCKS OF THE SOUTHWESTERN SIBERIAN CRATON: PRELIMINARY GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERIZATION

Геодинамика и тектонофизика, 2017
The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011].
A. V. Ivanov, I. V. Levitsky, V. I. Levitsky, E. I. Demonterova, L Z. Reznitsky   +4 more
doaj   +1 more source

Marine Phosphate Level During the Archean Constrained by the Global Redox Budget

Geophysical Research Letters
Understanding the oceanic phosphate concentration is critical for understanding marine productivity and oxygen evolution throughout Earth history. During the Archean, estimates of marine phosphate levels range from scarce to enriched conditions. However,
Yasuto Watanabe, Kazumi Ozaki, Eiichi Tajika   +2 more
doaj   +1 more source

Archean sedimentary styles and early crustal evolution [PDF]

, 1986
The distinctions between and implications of early and late Archean sedimentary styles are presented. Early Archean greenstone belts, such as the Barberton of South Africa and those in the eastern Pilbar Block of Australia are characterized by fresh or ...
Lowe, D. R.
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