Evolution of high‐Mg–Al granulites from Sunkarametta, Eastern Ghats, India: evidence for a lower crustal heating–cooling trajectory
Evolution of high‐Mg–Al granulites from Sunkarametta, Eastern Ghats, India: evidence for a lower crustal heating–cooling trajectory
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印度东高止山脉孙卡拉梅塔高镁铝麻粒岩的演化：下地壳加热-冷却轨迹的证据
DOI：
10.1046/j.1525-1314.2000.00253.x
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发表时间：
2000
影响因子：
3.4
通讯作者：
Dasgupta
中科院分区：
文献类型：
--
作者：
Bose;Fukuoka;Sengupta;Dasgupta
印度东高止山脉带Sunkarametta的一套高镁铝麻粒岩在紧密相关的域中显示出对比鲜明的高铝斜方辉石+堇青石+镁铝尖晶石组合和类似的高铝斜方辉石+富钛尖晶石组合。结构和成分特征表明，两者都来自黑云母-斜长石-石英含原岩的脱水-熔融。前者组合稳定在相对较多的镁体成分。地质温压数据和岩石成因格网的考虑，把“峰值”变质条件在c。950 °C和9 kbar。 在高峰变质作用之后，岩石冷却到c。700-750 °C，压力略有下降，逆行反应也涉及熔体-固体相互作用。 推测的P-T轨迹是地壳下部（25-30 km）的加热-冷却轨迹。
A suite of high‐Mg–Al granulites from Sunkarametta, Eastern Ghats Belt, India, shows contrasting prograde assemblages of extremely aluminous orthopyroxene+cordierite+sapphirine and similarly aluminous orthopyroxene+Ti‐rich spinel in closely associated domains. Textural and compositional characteristics indicate that both were derived from prograde dehydration–melting of biotite–plagioclase–quartz‐bearing protoliths. The former assemblage was stabilized at relatively more magnesian bulk composition. Geothermobarometric data and petrogenetic grid considerations place ‘peak’ metamorphic conditions at c. 950 °C and 9 kbar. Subsequent to peak metamorphism, the rocks cooled to c. 700–750 °C, with slight lowering of pressure, and the retrograde reactions also involved melt–solid interaction. The inferred P–T trajectory is one of heating–cooling at lower crustal (25–30 km) depths.