Tectonic framework of Narmada-Son Lineament - A continental rift system in central India from deep seismic soundings

1986 ◽  
pp. 133-150 ◽  
Author(s):  
K. L. Kaila
Keyword(s):  
Central India ◽  
Continental Rift ◽  
Rift System ◽  
Deep Seismic Soundings ◽  
Tectonic Framework

scholarly journals Sr and Nd isotopic characteristics of 1.77-1.58 Ga rift-related granites and volcanics of the Goiás tin province, central Brazil

2001 ◽  
Vol 73 (2) ◽  
pp. 263-276 ◽  
Author(s):  
MÁRCIO M. PIMENTEL ◽  
NILSON F. BOTELHO
Keyword(s):  
Continental Rift ◽  
Rift System ◽  
Isotopic Data ◽  
Sialic Crust ◽  
Central Brazil ◽  
T Values

Supracrustal rocks of the Araí Group, together with coeval A-type granites represent a ca. 1.77-1.58 Ga old continental rift in Brazil. Two granite families are identified: the older (1.77 Ga) group forms small undeformed plutons, and the younger granites (ca. 1.58 Ga) constitute larger, deformed plutons. Sr-Nd isotopic data for these rocks indicate that the magmatism is mostly product of re-melting of Paleoproterozoic sialic crust. Initial Sr ratios for both granite families are ca 0.726 and 0.720. Most TDM model ages are between 2.58 and 1.80 Ga. epsilonND(T) values are between +3.6 and -11.9. Araí volcanics are bimodal, with basalts and dacites/rhyolites interlayered with continental sediments. The felsic volcanics show Nd isotopic characteristics which are very similar to the granites, and are also interpreted as reworking of Paleoproterozoic crust. Detrital sediments of the Araí Group revealed T DM model ages between 2.4 and 2.16 Ga, indicating that they are the product of erosion of Paleoproterozoic crust. The data indicate that the Araí rift system was established on crust that had just become stable after the Paleoproterozoic orogeny.

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