TY - JOUR
T1 - Thermal evolution of archean basement rocks from the eastern part of the north china craton and its bearing on tectonic setting
AU - Zhao, Guochun
AU - Wilde, S. A.
AU - Cawood, P. A.
AU - Lu, Liangzhao
PY - 1998/1/1
Y1 - 1998/1/1
N2 - The basement rocks in the eastern zone of the North China craton are composed predominantly of pretectonic tonalitic-trondhjemitic-granodioritic gneisses and syntectonic granitoids, with rafts of supracrustal rocks consisting of ultramafic to felsic volcanic and sedimentary rocks, metamorphosed over a range of conditions from greenschist to granulite facies. Most mafic granulites, amphibolites, and some pelitic gneisses and schists preserve the prograde, peak, and post-peak textures. The prograde metamorphic stage is indicated by mineral inclusions within minerals of the peak stage, represented by the assemblages of hornblende + plagioclase + quartz ± biotite in mafic granulites, chlorite + actinolite + epidote + plagioclase + quartz in amphibolites, and biotite + plagioclase + quartz in pelitic gneisses. The peak stage is shown by assemblages of orthopyroxene + clinopyroxene + garnet + plagioclase + quartz in the mafic granulites, hornblende + plagioclase + quartz + garnet in garnetiferous amphibolites, and garnet + sillimanite + plagioclase + quartz + biotite in pelitic gneisses. The post-peak stage is represented by garnet + quartz symplectic coronas in mafic granulites, actinolite + garnet retrogressive rims around garnet or hornblende grains in amphibolites, and kyanite replacing sillimanite or staurolite replacing sillimanite + garnet in pelitic gneisses. These textural relations and their P-T estimates define counterclockwise P-T paths. The P-T-t(ime) paths of metamorphic rocks from the eastern zone reflect an origin related to the intrusion and underplating of large amounts of mantle-derived magmas that not only provided heat for the metamorphism but also added a large volume of mostly mafic material to the base of the crust. Crustal growth therefore was dominated by vertical addition of mantle-derived magmas to the crust. Combined with lithologic, structural, metamorphic, and geochronologic considerations, these large volumes of underplated magma are considered to be related to upwelling mantle plumes (hotspots).
AB - The basement rocks in the eastern zone of the North China craton are composed predominantly of pretectonic tonalitic-trondhjemitic-granodioritic gneisses and syntectonic granitoids, with rafts of supracrustal rocks consisting of ultramafic to felsic volcanic and sedimentary rocks, metamorphosed over a range of conditions from greenschist to granulite facies. Most mafic granulites, amphibolites, and some pelitic gneisses and schists preserve the prograde, peak, and post-peak textures. The prograde metamorphic stage is indicated by mineral inclusions within minerals of the peak stage, represented by the assemblages of hornblende + plagioclase + quartz ± biotite in mafic granulites, chlorite + actinolite + epidote + plagioclase + quartz in amphibolites, and biotite + plagioclase + quartz in pelitic gneisses. The peak stage is shown by assemblages of orthopyroxene + clinopyroxene + garnet + plagioclase + quartz in the mafic granulites, hornblende + plagioclase + quartz + garnet in garnetiferous amphibolites, and garnet + sillimanite + plagioclase + quartz + biotite in pelitic gneisses. The post-peak stage is represented by garnet + quartz symplectic coronas in mafic granulites, actinolite + garnet retrogressive rims around garnet or hornblende grains in amphibolites, and kyanite replacing sillimanite or staurolite replacing sillimanite + garnet in pelitic gneisses. These textural relations and their P-T estimates define counterclockwise P-T paths. The P-T-t(ime) paths of metamorphic rocks from the eastern zone reflect an origin related to the intrusion and underplating of large amounts of mantle-derived magmas that not only provided heat for the metamorphism but also added a large volume of mostly mafic material to the base of the crust. Crustal growth therefore was dominated by vertical addition of mantle-derived magmas to the crust. Combined with lithologic, structural, metamorphic, and geochronologic considerations, these large volumes of underplated magma are considered to be related to upwelling mantle plumes (hotspots).
UR - http://www.scopus.com/inward/record.url?scp=0032456534&partnerID=8YFLogxK
U2 - 10.1080/00206819809465233
DO - 10.1080/00206819809465233
M3 - Article
AN - SCOPUS:0032456534
SN - 0020-6814
VL - 40
SP - 706
EP - 721
JO - International Geology Review
JF - International Geology Review
IS - 8
ER -