Sr–Nd–Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil)

2013 ◽  
Vol 46 ◽  
pp. 9-25 ◽  
Author(s):  
Eduardo R.V. Rocha-Júnior ◽  
Leila S. Marques ◽  
Marly Babinski ◽  
Antônio J.R. Nardy ◽  
Ana M.G. Figueiredo ◽  
...  
Keyword(s):  
Flood Basalts ◽  
Continental Flood Basalts ◽  
Mantle Sources ◽  
Isotopic Constraints

scholarly journals Lead isotope constraints on the mantle sources involved in the genesis of Mesozoic high-Ti tholeiite dykes (Urubici type) from the São Francisco Craton (Southern Espinhaço, Brazil)

2016 ◽  
Vol 46 (suppl 1) ◽  
pp. 105-122 ◽  
Author(s):  
Leila Soares Marques ◽  
Eduardo Reis Viana Rocha-Júnior ◽  
Marly Babinski ◽  
Karine Zuccolan Carvas ◽  
Liliane Aparecida Petronilho ◽  
...  
Keyword(s):  
Mantle Source ◽  
Crustal Contamination ◽  
Experimental Tests ◽  
Pb Isotope ◽  
Flood Basalts ◽  
Nd Isotope ◽  
Continental Flood Basalts ◽  
Rock Fragments ◽  
Mantle Sources ◽  
First Results

ABSTRACT: The first results of Pb isotope compositions of the high-Ti Mesozoic dykes of the Southern Espinhaço are presented. The results do not show large variations and are significantly more radiogenic than the Pb isotope compositions of the high-Ti tholeiites from the Paraná Continental Flood Basalts. The data combined with published geochemical and Sr-Nd isotope results rule out crustal contamination processes in the genesis of the dykes, requiring magma generation in metasomatized subcontinental lithospheric mantle with the involvement of HIMU-type and carbonatite components. The magmas may have been also derived from a mantle source containing ~4 - 5% of pyroxenite and ~1% of carbonatite melts, agreeing with published Os isotope compositions of high-Ti rocks from the Paraná Continental Flood Basalts. These metasomatizing agents could be responsible for mantle source refertilization, as was also proposed in the literature to explain the characteristics of xenoliths of the Goiás Alkaline Province, which also occurs in the border of the São Francisco Craton. Additionally, to evaluate the risks of Pb contamination during sample preparation for analysis, several experimental tests were accomplished, which indicate the need of sawed surface removal and a careful washing of small-sized rock fragments before powdering, especially for rocks with [Pb] < 7 µg/g.

scholarly journals Continental Flood Basalts and Mantle Plumes: a Case Study of the Northern Ethiopian Plateau

2009 ◽  
Vol 50 (7) ◽  
pp. 1377-1403 ◽  
Author(s):  
L. Beccaluva ◽  
G. Bianchini ◽  
C. Natali ◽  
F. Siena
Keyword(s):  
Mantle Plumes ◽  
Flood Basalts ◽  
Continental Flood Basalts ◽  
Ethiopian Plateau

Peperite formed by lava flows over sediments: An example from the central Paraná Continental Flood Basalts, Brazil

2007 ◽  
Vol 159 (4) ◽  
pp. 343-354 ◽  
Author(s):  
Breno L. Waichel ◽  
Evandro F. de Lima ◽  
Carlos A. Sommer ◽  
Romulo Lubachesky
Keyword(s):  
Lava Flows ◽  
Flood Basalts ◽  
Continental Flood Basalts

A telltale signature of Archean lithospheric mantle in the Paraná continental flood basalts genesis

Lithos ◽  
2020 ◽  
Vol 364-365 ◽  
pp. 105519
Author(s):  
E.R.V. Rocha-Júnior ◽  
L.S. Marques ◽  
M. Babinski ◽  
F.B. Machado ◽  
L.A. Petronilho ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Flood Basalts ◽  
Continental Flood Basalts

Cyclical variation in composition in continental tholeiites of East Greenland

1989 ◽  
Vol 26 (3) ◽  
pp. 534-543 ◽  
Author(s):  
A. J. Hogg ◽  
J. J. Fawcett ◽  
J. Gittins ◽  
M. P. Gorton
Keyword(s):  
North Atlantic Ocean ◽  
Tholeiitic Basalt ◽  
Primitive Mantle ◽  
Magma Chambers ◽  
Flood Basalts ◽  
East Greenland ◽  
Continental Flood Basalts ◽  
Tholeiitic Magma ◽  
Small Reservoirs ◽  
The North

The Prinsen of Wales Bjerge (PWB), part of the Tertiary volcanic province of East Greenland, consists of tholeiitic basalts overlain by alkalic basalts that were erupted 100–150 km west of the original axis of continental rifting and active ocean-floor development during the creation of the North Atlantic Ocean. They have many features of continental flood basalts but are somewhat enriched in Fe and in Ti relative to Fe and have slightly lower Al2O3. They have slight enrichments in the light rare-earth elements (La/Yb = 3–4). A nunatak within the PWB displays four cycles of tholeiitic basalt, each about 50 m thick, which are defined by trace-element variations (Ni, Cr, Sr, Zr, and Zr/Y). In three of the four cycles the lowermost flows are the most highly differentiated, and successive flows are increasingly primitive. These changes are thought to be the result of frequent injection of primitive, mantle-derived tholeiitic magma into small crustal magma chambers that contain evolved tholeiitic magma. The resultant mixing and expulsion of hybrid magma produce flows of small volume (0.01–0.03 km3) that display increasingly primitive character upward within each cycle (increasing Mg# and decreasing content of incompatible elements). This process is expected to be more efficient in small reservoirs than in the very large magma chambers that have been invoked by previous exponents of the differentiation–replenishment hypothesis. We suggest that cyclical volcanism in areas well back from the line of active rifting may be more common than is realized and is controlled by the fractionation–magma-replenishment process operating in numerous small reservoirs in an extensively fractured continental crust.

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