40Ar-39Ar age of carbonatite-alkaline magmatism in Sung valley, Meghalaya, India |
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| Authors: | Jyotiranjan S Ray Kanchan Pande |
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| Institution: | (1) Physical Research Laboratory, Navrangpura, 380 009 Ahmedabad, India;(2) Ottawa-Carleton Geoscience Centre, University of Ottawa, K1N 6N5 Ottawa, ON, Canada |
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| Abstract: | 40Ar-39Ar analyses of one alkali pyroxenite whole rock and two phlogopite separates of calcite carbonatites from the Sung Valley
carbonatite-alkaline complex, which is believed to be a part of the Rajmahal-Bengal-Sylhet (RBS) flood basalt province, yielded
indistinguishable plateau ages of 108.8 ± 2.0Ma, 106.4 ± 1.3Ma and 107.5 ± 1.4Ma, respectively. The weighted mean of these
ages, 107.2 ± 0.8 Ma, is the time of emplacement of this complex. This implies that Sung Valley complex and probably other
such complexes in the Assam-Meghalaya Plateau postdate the main flood basalt event (i.e., the eruption of tholeiites) in the
RBS province by ∼10Ma. |
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| Keywords: | 40Ar-39Ar dating carbonatite Sung Valley Rajmahal Traps Kerguelen plume |
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