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Title: Evolution of alkaline carbonatite complex of Samchampi Samteran area Karbi Anglong Assam
Researcher: Sengupta, Shyamal Kumar
Guide(s): Rahman, S
Keywords: Alkaline-Carbonatite
University: Gauhati University
Completed Date: 31/01/1997
Abstract: The alkaline carbonatite complex of Samchampi-Samteran is a part of major alkaline-carbonatite belt extending from Meghalaya to Assam. The Complex is near circular ( 12km2 in area) occurs at the intersection of ENE and NNE lineaments. The litho units are magnetite +- apatite +- perovskite rock, pyroxenite, alkali pyroxenite- melteigite- ijolite, shonkinite, nepheline/foidal syenite, alkali syenite, phonolite and volcanic tuff. Carbonatites are intricately associated with these rocks. Fenites and syenitic fenites are the most dominant rock types in the area. Phosphatic-chert breccia, secondary in nature, is also present in the Complex. The alkaline mafic - ultramafic are predominantly agpaitic and silica undersaturated, while the late fractionates are miaskitic and distinctly alkaline. The carbonatites are calcio, magnesio and ferro-carbonatites. The silicates are the fractional crystallization differentiation of parental magma which through process of liquid immiscibility caused the development of carbonatite melt. The parental magma as deduced for the alkaline complex is calcium rich ultramafic composition charged with volatiles, which has high Mg* values and also peralkaline. The fenitization includes both sodic and potassic types and formed by both carbonatites and mafic alkaline rocks into the gneissic country rocks. The complex shows enrichment in some incompatible elements like K, P, Zr, Nb, Rb, Ba, SR and Th. The similar rations of Zr/Y and Nb/Zr and Log ( Zr/Ti02) indicate the rocks of the complex are co-magmatic. The pristine carbonatites have 0 = 7.2% SMOW and C = -3.84%. PDB indicating their temperature of formation between 7000C and 11000C and are mantle derived.
Appears in Departments:Department of Geological Science

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01_title page.pdfAttached File21.77 kBAdobe PDFView/Open
02_certificate.pdf22.46 kBAdobe PDFView/Open
03_abbreviations used.pdf22.2 kBAdobe PDFView/Open
04_content.pdf81.61 kBAdobe PDFView/Open
05_list of figures.pdf96.62 kBAdobe PDFView/Open
06_list of plates.pdf135.8 kBAdobe PDFView/Open
07_list of tables.pdf42.23 kBAdobe PDFView/Open
08_abstract.pdf33.76 kBAdobe PDFView/Open
09_chapter 1.pdf1.42 MBAdobe PDFView/Open
10_chapter 2.pdf4.58 MBAdobe PDFView/Open
11_chapter 3.pdf481.79 kBAdobe PDFView/Open
12_chapter 4.pdf368.74 kBAdobe PDFView/Open
13_chapter 5.pdf3.94 MBAdobe PDFView/Open
14_chapter 6.pdf4.52 MBAdobe PDFView/Open
15_chapter 7.pdf2.25 MBAdobe PDFView/Open
16_chapter 8.pdf2.58 MBAdobe PDFView/Open
17_chapter 9.pdf195.82 kBAdobe PDFView/Open
18_chapter 10.pdf1.98 MBAdobe PDFView/Open
19_summary and conclusion.pdf145 kBAdobe PDFView/Open
20_acknowledgement.pdf49.04 kBAdobe PDFView/Open
21_references.pdf509.4 kBAdobe PDFView/Open
22_glossary.pdf68.59 kBAdobe PDFView/Open

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