Geology of the Grove Mountains in East Antarctica——New evidence for the final suture of Gondwana Land  

作　　者：刘小汉 赵越 刘晓春 俞良军 

机构地区：[1]Laboratory of Lithosphere Tectonic Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences [2]Institute of Geomechanics, Chinese Academy of Geological Sciences

出　　处：《Science China Earth Sciences》2003年第4期305-319,共15页中国科学（地球科学英文版）

基　　金：Financial support is given by Chinese Academy of Sciences(Grant No.KZCX2-303);the Ministry of Science and Technology of China(Grant No.98-927-01-06).

摘　　要：Grove Mountains consists mainly of a series of high-grade (upper amphibolite to granu-lite facies) metamorphic rocks, including felsic granulite, granitic gneiss, mafic granulite lenses and charnockite, intruded by late tectonic gneissic granite and post-tectonic granodioritic veins. Geo-chemical analysis demonstrates that the charnockite, granitic gneiss and granite belonged to aluminous A type plutonic rocks, whereas the felsic and mafic granulite were from supracrustal materials as island-arc, oceanic island and middle oceanic ridge basalt. A few high-strained shear zones disperse in regional stable sub-horizontal foliated metamorphic rocks. Three generations of ductile deformation were identified, in which D1 is related to the event before Pan-African age, D2 corresponds to the regional granulite peak metamorphism, whereas D3 reflects ductile extension in late Pan-African orogenic period. The metamorphic reactions from granitic gneiss indicate a single granulite facies event, but 3 steps from mafic granulite, with P-T condition of M1 800℃, 9.3×105 Pa; M2 800—810℃, 6.4×105 Pa ; and M3 650℃ have been recognized. The U-Pb age data from representative granitic gneiss indicate (529±14) Ma of peak metamorphism, (534±5) Ma of gran-ite emplacement, and (501±7) Ma of post-tectonic granodioritic veins. All these evidences sug-gest that a huge Pan-African aged mobile belt exists in the East Antarctic Shield extending from Prydz Bay via Grove Mountains to the southern Prince Charles Mountains. This orogenic belt could be the final suture during the Gondwana Land assemblage.Grove Mountains consists mainly of a series of high-grade (upper amphibolite to granu-lite facies) metamorphic rocks, including felsic granulite, granitic gneiss, mafic granulite lenses and charnockite, intruded by late tectonic gneissic granite and post-tectonic granodioritic veins. Geo-chemical analysis demonstrates that the charnockite, granitic gneiss and granite belonged to aluminous A type plutonic rocks, whereas the felsic and mafic granulite were from supracrustal materials as island-arc, oceanic island and middle oceanic ridge basalt. A few high-strained shear zones disperse in regional stable sub-horizontal foliated metamorphic rocks. Three generations of ductile deformation were identified, in which D1 is related to the event before Pan-African age, D2 corresponds to the regional granulite peak metamorphism, whereas D3 reflects ductile extension in late Pan-African orogenic period. The metamorphic reactions from granitic gneiss indicate a single granulite facies event, but 3 steps from mafic granulite, with P-T condition of M1 800℃, 9.3×105 Pa; M2 800—810℃, 6.4×105 Pa ; and M3 650℃ have been recognized. The U-Pb age data from representative granitic gneiss indicate (529±14) Ma of peak metamorphism, (534±5) Ma of gran-ite emplacement, and (501±7) Ma of post-tectonic granodioritic veins. All these evidences sug-gest that a huge Pan-African aged mobile belt exists in the East Antarctic Shield extending from Prydz Bay via Grove Mountains to the southern Prince Charles Mountains. This orogenic belt could be the final suture during the Gondwana Land assemblage.

关 键 词：East Antarctic Shield  Grove Mountains  PAN-AFRICAN orogen  GONDWANA Land  FINAL suture. 

分 类 号：P585[天文地球—岩石学]