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Transcript of Bhutan: a magic country with magic geology - metamorphic ... · Bhutan: a magic country with magic...
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Palaeomagnetic sampling along them major highway of the country
Bhutan: a magic country with magic geology - metamorphic, structural, thermal and rock magnetic history of the Pele La profile
István Dunkl, Eva Schill and J. Florian Wellmann
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[Gansser, Geology of the Bhutan Himalaya, 1983]
Geology
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Simplified geological map of Bhutan [Grujic et al., 2002]
Geology
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Geology
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Geology, concept of thermo remanent rock magnetism
[Wellmann, 2004]
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Fine, laminated clayey and sandymetasediment with crenulation and oblique schistosity
Biotite schist with well developedcrystals
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Orientations of bioties and the schistosity indicate two overprint phases
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Skeletal garnet
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Euhedral garnets in thegarnet-amphibolite
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Tourmalinite
Tourmaline growth (metasomatism)postdates the folding
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Mineral chemistry
amphibole
biotite
Al = 4
(MgFe)
(MgFe)
(MgFe)
(MgFe)
(MgFe)
(MgFe)
Al = 6
Al = 2
Si = 7
Si = 6
Si = 5
Si = 4
tot
tot
tot
MuscoviteSiderophyllite
PhlogopiteAnnite
Phengite
01
2345
white mica
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Mol. % MgCO in calcite3
Mol
. % F
eCO
in
calc
ite3
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.00 0.50 1.00 1.50
3248 m3010 m2930 m2735 m
Mg and Fe in the calcite of the marbles. The higher values mean higher peakmetamorphic conditions, but the bulk chemistry plays also some role
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U/Pb concordia plots for samples from eastern Bhutan
[Daniel et al., 2003]
Summary P-T-t diagram showing monazite & xenotime ages and estimated peak metamorphic conditions for the uppermost Lesser Himalayan rocks of E. Bhutan
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BiotiteWhite micaZircon FT
Ele
vatio
n [m
]
K/Ar and FT zircon age [Ma]
5 10 15 202000
2500
3000
3500
Relation of elevation and radiometric ages