Results 21 to 30 of about 382,485 (102)

PETROGRAFIA E LITOQUÍMICA DE DIQUES MÁFICOS MESOZOICOS E CAMBRIANOS(?) DE MINAS GERAIS: COMPARAÇÕES COM BASALTOS DA PROVÍNCIA PARANÁ-ETENDEKA E COM DIQUES DA SUÍTE FUNDÃO

open access: yes, 2016
Resumo Minas Gerais (MG) guarda diversas geracoes de diques maficos, com idade desde o Paleoproterozoico ao Cretaceo. Datam do Cretaceo os enxames de diques Transminas e Serra do Mar, e ha possiveis representantes do Cambriano denominados Suite Fundao ...
R. Coelho, Alexandre de Oliveira Chaves
semanticscholar   +1 more source

LITOQUÍMICA DOS DIQUES MÁFICOS PARÁ DE MINAS (MG-BRASIL) ASSOCIADOS À UMA PROVÁVEL PLUMA MANTÉLICA ESTATERIANA DE MATO GROSSO-GOIÁS

open access: yes, 2014
Os diques maficos do Enxame Para de Minas-MG (1,72 Ga) apresentam-se majoritariamente como diabasios faneriticos e as vezes como corpos porfiriticos, com fenocristais de plagioclasio.
Alexandre de Oliveira Chaves
semanticscholar   +1 more source

Granitóides da Parte Centro/Sudoeste do Escudo Sul-rio-grandense. Novos Dados e Discussões sobre Gênese e Tipologia do Magmatismo Alcalino.

open access: yes, 1992
As caracteristicas petrograficas e geoquimicas do Complexo Anelar Leoes, dos diques intermediarios Armeiras e do Quartzo Monzonito da Tuna indicam sua afinidade alcalina e justificam seu enquadramento na Suite Intrusiva Saibro, na porcao ocidental do ...
M. C. P. Gastal, R. Schimitt, L. Nardi
semanticscholar   +1 more source

Texturas e inclusões em cromita da Mina Ipueira: contribuição para o entendimento da formação de cromititos no Complexo Jacurici, BA

open access: yesRevista de Geociências do Nordeste
A cromita é um mineral do grupo dos espinélios e constitui a única fonte de cromo metálico, sendo essencial na produção de aço inoxidável. A formação de cromititos tem sido alvo de debate. No Brasil, o Complexo máfico-ultramáfico Jacurici, explorado pela
Greice Oliveira Roloff   +3 more
semanticscholar   +1 more source

Crustal flow beneath Iceland [PDF]

open access: yes
Theoretical and experimental studies indicate that when oceanic crust is hotter than about 800°C, variations in crustal thickness drive lower crustal flow.
Maclennan, J., Jones, S. M.
core   +1 more source

Crustal accretion at the Reykjanes Ridge, 61°–62°N [PDF]

open access: yes
We report results of a seismic, gravity, and magnetic survey of the Reykjanes Ridge spreading center at 61°–62°N, about 600 km from the center of the Iceland mantle plume.
Smallwood, John R., White, Robert S.
core   +1 more source

Quantifying Crustal Thickness in Continental Collisional Belts: Global Perspective and a Geologic Application

open access: yesScientific Reports, 2017
We present compiled geochemical data of young (mostly Pliocene-present) intermediate magmatic rocks from continental collisional belts and correlations between their whole-rock Sr/Y and La/Yb ratios and modern crustal thickness. These correlations, which
F. Hu, M. Ducea, Shu-Wen Liu, J. Chapman
semanticscholar   +1 more source

Segmentation and cycles of crustal accretion at mid-ocean ridges: a study of the Reykjanes Ridge [PDF]

open access: yes, 2003
Early studies of mid-ocean ridges suggest a fundamental difference between crustal accretionary processes at slow- and fast-spreading ridges. Accretion, and the supply of melt to the crust itself, is thought to be highly episodic at slow-spreading ridges
Gardiner, Alexander B.
core  

Fully nonlinear inversion of fundamental mode surface waves for a global crustal model [PDF]

open access: yes, 2007
We use neural networks to find 1-dimensional marginal probability density functions (pdfs) of global crustal parameters. The information content of the full posterior and prior pdfs can quantify the extent to which a parameter is constrained by the data.
Meier, U.   +2 more
core   +1 more source

Stagnant lids and mantle overturns: Implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics

open access: yes, 2018
The lower plate is the dominant agent in modern convergent margins characterized by active subduction, as negatively buoyant oceanic lithosphere sinks into the asthenosphere under its own weight. This is a strong plate-driving force because the slab-pull
J. Bédard
semanticscholar   +1 more source

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