iron ore group, eastern indian craton asish basu university of rochester new york 14627
TRANSCRIPT
Iron Ore Group, Eastern Indian Craton
Asish BasuUniversity of Rochester
New York 14627
Geological map of the Eastern Indian Craton in the Singhbhum-Orissa region of the Indian continent (see inset) modified after [13] and [17]. The current study area is to the north of Bonai Granite. The sandstones of this study are from the Darjing group, west of Singhbhum Granite. Samples analyzed are from a sedimentary succession shown by the crossed box. Abbreviations: OMG, Older Metamorphic Group; OMTG, Older Metamorphic Tonatile Gneisses. The ages of the relevant rocks are: Tamperkola Granite, ~2.8 Ga; Bonai Granite, ~3.2 Ga; Singhbhum Granite Complex, ~ 3.1 Ga; OMTG, ~3.3 Ga; OMG, ~ 3.3Ga. See text for geologic-lithologic details.
Nb/Ta ratios vs. Zr/Sm ratios of the analyzed sandstones compared to the Archean tonalite-trondhjemite gneisses (TTGs) and present day continental crust and adakites. Also shown are modern day MORBs, OIBs, and island arc basalts (IABs)[38]. The sandstones of this study are identical to Archean TTGs, indicating that the protoliths of the sandstones formed in similar petrotectonic environment.
Iron Ore Group
Upper Lava
}3 KmUpper Shale with Mn Ore
Banded Iron Ore ~0.7 Km
Lower shale and tuff ~1.9 KmTuffaceous rocks ~30m at the top; gradational with Lower Shale
Lower Lava ~3 Km
Th/U = 1.7 to 2.5
0.5 mm
Lower Lava (Western Limb)
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
1
10
100
Lower Lava (Eastern Limb, Noamundi)
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu1
10
100Lower Lava (Eastern Limb, Jilling)
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu1
10
100
Upper Lava
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
1
10
100
1000
Lower Shale
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
0.1
1
10
100
1000
Upper Shale
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
1
10
100
Tuff (4/03)
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
1
10
100
1000
10000
Age = 3.4GaNd(T) = -4.9Nd(0) = -38.2
Tuff (4/03)
La Ce Pr NdSmEu Gd Tb Dy Ho Er TmYb Lu
Rock/ Chondrite
1
10
100
1000
10000
Tuff
BaRb Th U Nb La Pb Ce Sr NdSm Zr Hf EuGdTb Dy Y Er Yb
Rock/ NMORB
0.1
1
10
100
1000
10000
Lower Lava (western limb)
BaRb Th U Nb La Pb Ce Sr NdSm Zr Hf EuGdTb Dy Y Er Yb
Rock/ NMORB
0.1
1
10
100
Lower Lava (Western limb)
Nd(3.4Ga)
0 2 4 6 8
# Samples
0
1
2
3
4
Lower Lava (Eastern limb)
Nd(3.4Ga)
0 1 2 3 4 5 6 7 8
# Samples
0
1
2
3
4
Upper Lava
Nd(3.4Ga)
0 2 4 6 8
# Samples
0
1
2
3
4
Nd(3.4Ga) = +2.8 to +6.8
Nd(3.4Ga) = +0.4 to +3.8 Nd(3.4Ga) = +0.8 to +6.0
Geological map of the Eastern Indian Craton in the Singhbhum-Orissa region of the Indian continent (see inset) modified after [13] and [17]. The current study area is to the north of Bonai Granite. The sandstones of this study are from the Darjing group, west of Singhbhum Granite. Samples analyzed are from a sedimentary succession shown by the crossed box. Abbreviations: OMG, Older Metamorphic Group; OMTG, Older Metamorphic Tonatile Gneisses. The ages of the relevant rocks are: Tamperkola Granite, ~2.8 Ga; Bonai Granite, ~3.2 Ga; Singhbhum Granite Complex, ~ 3.1 Ga; OMTG, ~3.3 Ga; OMG, ~ 3.3Ga. See text for geologic-lithologic details.