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    Abstract:

    The NeQarchea}n complex in eastern Hengsha.n is composed of Dongzhuang supracrustal rocks and Tuling- Linchang TTG gneisses. Mafic granulites of Dongzhuang Formation contain two-stages of mineral assemblages, with the second assemblage (M3) of Hb+Pl mantling the first assemblage (M2) of OPx+ GPx + P1±Gtand often. occurring as symplectic coronas passing between OPx and Gt. After the earliest metamorphism (M1),the plagioclase-garnet-two pyroxene rocks occurring as inclusions in the TTG gneisses formed two-stage symplectic coronas around garnet. An outer corona of Hb+Pl mantles a finer- grained inner coidna of OPx+PI. Preferred P-T estimates for MI based on garnet-OPx pairs in the inclusions of Tuling-Linchang TTG gneisses are P about 1.l-1.5 GPa at 1108ºK.There exist some differences in P-T conditions for M2 and M3 between the inclusions and the host rocks of Tuling-Linchang TTG gneisses; with P-T for M2 aad M3 being respectively 1.0 GPa at 1148士25ºK and 0.4 GPa at 923士50ºK in the inclusions, and 0.9 GPa at 1123士20ºK and 0.4 GPa at 908士45ºK in Dongzhuang Formatiou. According to pressure, temperature and textures indicating mineral reac- tons, they have experienced different evolutionary processes. The PTt path of the inclusions is a `clockwise' path in which the barometric maximum precedes the thermal maximum, and initial retrograde path has large initial dP/dT, exhibiting isothermal decompression(ITD),whereas the PTt path of Dong- zhuang mafic gra.nulites is an"anticlockwise"path in which heating occurs prior to during the thickening, and initial retrograde path has small positive dP/dT, exhibiting isobaric cooling(IBC).Such differences are of great importance in discussing the evolution of the Neoarchean complex in this area.

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吉成林,李明荣,王仁民,1993,恒山东段新太古杂岩两种PTt轨迹的确定及其意义[J].岩石矿物学杂志,12(1):32~39. Ji Chenglin, Li Mingrong, Wang Renmin Institute of Ceology, Chinese Academy of Geological Sciences Institute of Geology, Academia Sinica Department of Geology, Peking University,1993,Determination and Significance of Two PTt Paths in the Neoarchean Complex of Eastern Hengshan[J]. Acta Petrologica et Mineralogica,12(1):32~39.

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