Mantle plume: the dynamic setting of the origin of Early Paleozoic mafic dykes in Ziyang, Shaanxi Province, Southern Qinling Block, China

2020 ◽  
Vol 39 (3) ◽  
pp. 307-325
Author(s):  
Xiaoqing Chen ◽  
Shen Liu ◽  
Caixia Feng ◽  
Ian M. Coulson ◽  
Yan Fan ◽  
...  
Keyword(s):  
Mantle Plume ◽  
Shaanxi Province ◽  
Early Paleozoic ◽  
Mafic Dykes ◽  
Dynamic Setting

U–Pb baddeleyite ages, distribution and geochemistry of 925Ma mafic dykes and 900Ma sills in the North China craton: Evidence for a Neoproterozoic mantle plume

Lithos ◽  
2011 ◽  
Vol 127 (1-2) ◽  
pp. 210-221 ◽  
Author(s):  
Peng Peng ◽  
Wouter Bleeker ◽  
Richard E. Ernst ◽  
Ulf Söderlund ◽  
Vicki McNicoll
Keyword(s):  
Mantle Plume ◽  
North China Craton ◽  
North China ◽  
Mafic Dykes ◽  
The North

scholarly journals Zircon U–Pb age, geochemical, and Sr–Nd–Hf isotopic constraints on the origin of mafic dykes in the Shaanxi Province, North China Craton, China

Lithos ◽  
2013 ◽  
Vol 175-176 ◽  
pp. 244-254 ◽  
Author(s):  
Shen Liu ◽  
Caixia Feng ◽  
Bor-ming Jahn ◽  
Ruizhong Hu ◽  
Shan Gao ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Shaanxi Province ◽  
Mafic Dykes ◽  
Isotopic Constraints

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

2014 ◽  
Author(s):  
Alexandre de Oliveira Chaves
Keyword(s):  
Mantle Plume ◽  
Crustal Contamination ◽  
Oceanic Island ◽  
Initial Ratio ◽  
Mato Grosso ◽  
Mafic Dykes ◽  
Southeast Brazil ◽  
Basic Magmatism ◽  
Oceanic Island Basalts

Os diques máficos do Enxame Pará de Minas-MG (1,72 Ga) apresentam-se majoritariamente como diabásios faneríticos e às vezes como corpos porfiríticos, com fenocristais de plagioclásio. São litoquimicamente caracterizados como basaltos de alto-titânio, na sua maioria subalcalinos, sendo alguns alcalinos. Guardam anomalias negativas de európio e estrôncio associadas ao fracionamento do plagioclásio, bem como anomalias negativas de nióbio e razão inicial 87Sr/86Sr elevada aparentemente relacionadas a possíveis processos de contaminação crustal. Destaca-se sua assinatura de fonte enriquecida em elementos incompatíveis tipo OIB (oceanic island basalts). Tais características químicas, em associação aos registros de fluxo magmático subhorizontal dos diques e aos processos Estaterianos contemporâneos de rifteamento, sedimentação e magmatismo bimodal (ácido e básico) anorogênico, remetem à atividade de uma pluma mantélica no centro-sudeste do Brasil ao final do Paleoproterozóico.Palavras-chave: Diques máficos, OIB, pluma mantélica, Estateriano, Brasil. Abstract: LITHOCHEMISTRY OF THE PARÁ DE MINAS MAFIC DYKES RELATED TO A PROBABLE STATHERIAN MANTLE PLUME OF MATO GROSSO-GOIÁS (BRAZIL). Mafic dykes of the Pará de Minas Swarm-MG (1.72 Ga) are essentially phaneritic dolerites and eventually porphiritic, with plagioclase phenocrysts. The lithochemistry of the dykes shows they are high-Ti subalkaline basalts, but high-Ti alkaline bodies are sometimes also found. All of them keep Eu and Sr negative anomalies related to plagioclase fractionation. Nb negative anomalies and high 87Sr/86Sr initial ratio associated to probable crustal contamination processes can also be verified. They show OIB-like (oceanic island basalts) enriched source signature. Such chemical features in association with their subhorizontal magmatic flow and Statherian contemporary processes of rifting, sedimentation, anorogenic bimodal acid and basic magmatism, refer to the mantle plume activity in the central and southeast Brazil at Late Paleoproterozoic.Keywords: Mafic dykes, OIB, mantle plume, Statherian, Brazil. 

Variations in Surface Textures of Quartz Sand using Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 494-495
Author(s):  
Eugene J. Amaral
Keyword(s):  
Electron Microscopy ◽  
Glass Industry ◽  
Glass Slide ◽  
Distilled Water ◽  
Early Paleozoic ◽  
Secondary Effects ◽  
Surface Textures ◽  
High Silica ◽  
Sand Deposit ◽  
The U.S

Examination of sand grain surfaces from early Paleozoic sandstones by electron microscopy reveals a variety of secondary effects caused by rock-forming processes after final deposition of the sand. Detailed studies were conducted on both coarse (≥0.71mm) and fine (=0.25mm) fractions of St. Peter Sandstone, a widespread sand deposit underlying much of the U.S. Central Interior and used in the glass industry because of its remarkably high silica purity.The very friable sandstone was disaggregated and sieved to obtain the two size fractions, and then cleaned by boiling in HCl to remove any iron impurities and rinsed in distilled water. The sand grains were then partially embedded by sprinkling them onto a glass slide coated with a thin tacky layer of latex. Direct platinum shadowed carbon replicas were made of the exposed sand grain surfaces, and were separated by dissolution of the silica in HF acid.

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