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Thermal gradients in the Sri Lankan granulite terrane: a garnet–biotite thermometric approach
Author(s) -
SAJEEV K.,
OSANAI Y.
Publication year - 2005
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.2005.00582.x
Subject(s) - geology , granulite , biotite , metamorphism , metamorphic rock , gneiss , geochemistry , terrane , quartz , geomorphology , seismology , tectonics , paleontology , facies , structural basin
Thermal zoning of the Highland Complex, Sri Lanka has been delineated using the Fe 2+ –Mg distribution coefficient between garnet and biotite from garnet–biotite gneiss samples collected with wide geographical distribution. In order to minimize the potential for retrograde Fe–Mg exchange and maximize the potential for retaining peak equilibrium K D (garnet–biotite) and temperature, garnet and biotite included within feldspar and quartz without other mineral inclusions have been selected. The calculated results indicate four distinct temperature contours with K D values varying from 1.84 to 6.38 and temperature varying from 996 to 591 °C. From the present results, it is possible to divide the Highland Complex into two major metamorphic zones: a high‐temperature area in the central region and a low‐temperature area in the south‐western and north‐eastern region. In conjunction with the metamorphic pressure variations estimated from the granulites of the Highland Complex in previous studies, it is shown that the high‐ and low‐temperature areas are complemented by a high‐pressure region towards the eastern side and a low‐pressure region towards the western side of this complex. This thermal dome is interpreted to be an artifact of the different crustal levels exhumed following Pan‐African metamorphism.