Trace, rare-earth element, and oxygen isotopic systematics for the genesis of banded iron-formations: Evidence from Kushtagi schist belt, Archaean Dharwar Craton, India

1996 ◽  
Vol 60 (17) ◽  
pp. 3285-3294 ◽  
Author(s):  
R.M.K. Khan ◽  
S. Das Sharma ◽  
D.J. Patil ◽  
S.M. Naqvi
1996 ◽  
Vol 14 (3-4) ◽  
pp. 161-164 ◽  
Author(s):  
Yasuhiro Kato ◽  
Takanori Kawakami ◽  
Takashi Kano ◽  
Keitaro Kunugiza ◽  
N.S. Swamy

1998 ◽  
Vol 62 (21-22) ◽  
pp. 3475-3497 ◽  
Author(s):  
Yasuhiro Kato ◽  
Izumi Ohta ◽  
Tomoki Tsunematsu ◽  
Yoshio Watanabe ◽  
Yukio Isozaki ◽  
...  

2010 ◽  
Vol 147 (5) ◽  
pp. 777-788 ◽  
Author(s):  
M. SANTOSH ◽  
V. J. RAJESH ◽  
T. TSUNOGAE ◽  
S. ARAI

AbstractWe report the occurrence and characteristics of diopsidite dykes and veins from the Palghat-Cauvery Suture Zone (PCSZ) marking the boundary between the Archaean Dharwar craton to the north and the Proterozoic Madurai Block to the south, which is considered as a trace of the Cambrian Gondwana suture zone in southern India. The diopsidites are composed predominantly of coarse crystals of diopside [Mg no. (100 Mg/(Mg+Fetot)) up to 89] surrounded by retrograde calcic amphibole, plagioclase and phlogopite with accessory titanite and calcite. The major, trace and rare earth element characteristics of the diopside crystals suggest their formation in a subduction zone setting. We correlate the petrogenesis of the diopsidites with the tectonics associated with the subduction and closure of the Neoproterozoic Mozambique Ocean prior to the final collisional assembly of the Gondwana supercontinent in Cambrian.


2020 ◽  
Author(s):  
Anirban Mitra ◽  
Sukanta Dey

<p>Use of trace and rare earth element concentration of terrigenous sedimentary rocks to deduce the composition of their source rocks in the hinterland is a very common and efficient practice. The results of geochemical analysis of the metaquartzarenites located at the basal part of Bababudan and Sigegudda belt, late Archean greenstone sequences of western Dharwar craton show that the sediments were most possibly supplied from Paleo to Mesoarchean granitoids of western Dharwar Craton. Rare earth element patterns of these basal quartzites display fractionated REE pattern in variable degree (La<sub>N</sub>/Yb<sub>N</sub> =1.47-10.63) with moderate to highly fractionated LREE (La<sub>N</sub>/Sm<sub>N</sub>=2.67-8.93) and nearly flat to slighly elevated HREE (Gd<sub>N</sub>/ Yb<sub>N</sub>=0.62-1.29) and a significant Eu negative anomaly (avg. Eu/Eu*=0.67). In general, presence of negative Eu anomaly in clastic rocks reflect the widespread occurrence of granitic rocks in the source area, which possess negative Eu anomaly. On the other hand, mechanical enrichment of zircon (having negative Eu anomaly, high HREE concentration and low La<sub>N</sub>/Yb<sub>N</sub>), if present, will hamper the whole REE pattern of the sediments and necessarily, do not actually mimic the source composition. Here, in our study, the Th/Sc vs Zr/Sc diagram show mineral Zircon has been concentrated by mechanical concentration in the sedimentary rocks. Few quartzite samples which have high Zr content typically exhibit low La<sub>N</sub>/Yb<sub>N</sub> values, reflecting pivotal role of mineral zircon in controlling the REE pattern of the sediments. Hence, in this case, we should be cautious in interpreting of the Eu negative anomaly of the basal quartzites for meticulously identifying their source rock composition. More geochemical and other analytical approaches are required in this regard.</p>


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