Aluminous and alkali-deficient tourmaline from the Singhbhum Shear Zone, East Indian shield: Insight for polyphase boron infiltration during regional metamorphism

2011 ◽  
Vol 96 (5-6) ◽  
pp. 752-767 ◽  
Author(s):  
N. Sengupta ◽  
P. Sengupta ◽  
H. K. Sachan
Keyword(s):  
Shear Zone ◽  
Regional Metamorphism ◽  
Indian Shield ◽  
East Indian ◽  
Singhbhum Shear Zone

scholarly journals First Report of Florencite from the Singhbhum Shear Zone of the East Indian Craton

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Maitrayee Chakraborty ◽  
Sayan Biswas ◽  
Nandini Sengupta ◽  
Pulak Sengupta
Keyword(s):  
Shear Zone ◽  
Small Proportion ◽  
Indian Shield ◽  
First Report ◽  
Precambrian Rocks ◽  
East Indian ◽  
Singhbhum Shear Zone ◽  
Geological Features ◽  
The World ◽  
Indian Craton

Metamorphic florencite is being reported from kyanite-rich rocks from the eastern part of the Palaeo- to Mesoproterozoic Singhbhum shear zone. This is the first report of florencite from the Precambrian rocks of the Indian Shield. Host rock of florencite is a kyanite-rich rock (>80  vol%) with small and variable amounts of quartz, lazulite, augelite, and rutile. Florencite forms small (<20 microns) idioblastic-to-subhedral crystals that are included in large kyanite grains. Rarely, florencite replaces kyanite. The florencite has small proportion of crandallite (8.7–11.8 mol%) and goyazite (<2 mol%) components. Florencite of this study is dominated by Ce (~49 mol%) with significant La (~30 mol%) and Nd (~21 mol%). Compared to other florencite occurrences of the world, florencite of the studied rock is impoverished in S, Sr, and Ba and rich in P. Stability of the assemblage florencite-kyanite-augelite-lazulite and the quantitative thermobarometry in the adjoining rocks suggest that florencite was formed during Palaeoproterozoic metamorphism that culminated at the P-T range of 490±40∘C and 6.3±1 kbar. Integrating all the geological features it is postulated that florencite was formed due to metasomatism of some aluminous protolith by infiltration of acidic fluids charged with PO4-3 and LREE.

Sedimentary and metamorphic lithofacies of the Lower Negaunee Iron Formation, Marquette District, Michigan, USA

2013 ◽  
Vol 50 (12) ◽  
pp. 1165-1177
Author(s):  
Natalie J. Pietrzak-Renaud
Keyword(s):  
Shear Zone ◽  
Mineral Assemblage ◽  
Regional Metamorphism ◽  
Regional Scale ◽  
Open Pit ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Brittle Fractures ◽  
Granular Iron ◽  
The Republic

The base of the Proterozoic Negaunee Iron Formation is exposed in the open pit at Tilden Mine, Marquette, Michigan. Juxtaposed against the Archean-aged Palmer Gneiss, it is bounded by the regional-scale Southern Shear Zone and cut by two sets of dykes: an older chloritic and schistose set and a younger 1.1 Ga Keweenawan set. Tilden Mine is dominated by a 100 m scale plunging northwest-anticline and is cut by a growth fault locally termed the Tower Hill Fault that intersects the Southern Shear Zone. The base of the exposed iron formation is composed of three lithofacies, including lower clastics that grade into the overlying banded iron formation that in turn grades upward into granular iron formation. This succession is capped by chloritic metadiabases locally termed the Summit Hill Sill and Pillar Intrusive. Petrographic and mineral chemical investigations document primary or early diagenetic hematite, siderite and possibly ferri-hydrite, metamorphic and related hydrothermal magnetite, chlorite, late martite overgrowing earlier magnetite and growth of specularite. All three lithofacies are cut by brittle fractures and late quartz veins. Brittle fractures are coated with chlorite, carbonate minerals, fluor-apatite, and sparse Cu-sulphides. These lithofacies document initial clastic sedimentation of strained detrital quartz into a subsiding fault trough. Over time, as subsidence slowed or sea level fluctuated, clastic deposition competed with quiescent chemical sedimentation, leading to deposition of the banded iron formation facies. As a stable shelf platform emerged, the granular iron formation facies was deposited via wave reworking of hardgrounds. Subsequent diagenesis initiated dissolution of carbonate and chert and promoted diagenetic replacement of primary iron minerals and chert. Regional metamorphism during Penokean orogeny at 1875–1835 Ma produced a suite of secondary metamorphic and related hydrothermal minerals. Metamorphism and hydrothermal flux related to the 1750 Ma development of the Republic Metamorphic Node overprinted the iron formation at Tilden to greenschist facies and infilled brittle fractures with a unique mineral assemblage. This unique mineral assemblage exhibits some striking similarities to Mn, Au, and Cu-sulphides documented at Champion Mine, west of Tilden, and proximal to the core of the Republic Node.

Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose

2013 ◽  
Vol 185 (9) ◽  
pp. 7833-7843 ◽  
Author(s):  
A. C. Patra ◽  
S. K. Sahoo ◽  
R. M. Tripathi ◽  
V. D. Puranik
Keyword(s):  
Shear Zone ◽  
Surface Soils ◽  
Singhbhum Shear Zone

Soda-granites from South of Tatanagar, Bihar, India

1966 ◽  
Vol 103 (4) ◽  
pp. 340-351 ◽  
Author(s):  
A. K. Banerji ◽  
A. K. Talapatra
Keyword(s):  
Partial Melting ◽  
Shear Zone ◽  
Confining Pressure ◽  
Residual Liquid ◽  
Copper Sulphide ◽  
Granite Magma ◽  
Singhbhum Shear Zone ◽  
Sudden Release ◽  
Singhbhum Granite

AbstractThe nature and origin of some soda-granites from the western part of the Singhbhum shear zone, Bihar, India, are discussed. These soda-granites are responsible for copper sulphide, apatite-magnetite, and uraniferous mineralization within the shear zone. Earlier workers regarded these rocks as sheared materials representing a portion of the high sodic residual liquid from the neighbouring Singhbhum granite magma. The present work indicates that these rocks are migmatitic in nature and are the products of progressive replacement of pre-existing pelitic and semi-pelitic schists by felspathic materials. Migmatization is essentially post-shearing in age while the Singhbhum granite is pre-shearing in age. The migmatitic materials appear to have been derived by the partial melting of the Singhbhum granite during shearing, particularly in depth, as a result of sudden release of confining pressure consequent upon shearing and generation of heat caused by friction at the base of the shear zone. The resulting liquids, which were albite rich, found easy passage through the shear zone and brought about migmatization and mineralization in its wake.

Sign in / Sign up

Export Citation Format

Share Document